CN112789788A

CN112789788A - Multiple motor product, motor group, driving device, and magnet group

Info

Publication number: CN112789788A
Application number: CN201980064493.6A
Authority: CN
Inventors: 藤川宪一; 田中伸幸; 尾关出光; 齐藤正一朗; 久米克也
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2018-10-04
Filing date: 2019-10-02
Publication date: 2021-05-11
Also published as: TW202023149A; JP2020078231A

Abstract

A plurality of identical motor products on the market, there are more than 30 motor products, each motor product includes 1 or 2 or more magnets, each magnet has a void ratio of 7% or less, and each magnet has a non-parallel orientation A sintered magnet in the area of and has a first main surface where the peak value of the surface magnetic flux density is the largest. When the surface magnetic flux density on the measurement line is measured on the first main surface of each magnet, the following formula is used for the magnet. Variation unevenness P between magnets P[%]=(σ _total [mT]/A _total [mT])×100 The variation unevenness P among magnets is 4% or less.

Description

Multiple motor product, motor group, driving device, and magnet group

Technical Field

The present invention relates to a motor and a motor set having a magnet, and a drive device having the magnet.

Background

Motors (electric motors) that convert electric energy into mechanical kinetic energy are widely used in the fields of machine tools, vehicles, airplanes, and the like. Such a motor includes a permanent magnet, and as the permanent magnet, for example, a parallel-oriented square magnet or a polar anisotropic ring magnet in which axes of easy magnetization are aligned in parallel is used.

However, it is known that a phenomenon called cogging torque, that is, a phenomenon in which the magnetic attraction force between the armature and the rotor fluctuates with respect to the rotation angle, occurs in the current motor. Since such cogging torque causes vibration and noise of the motor, it is desirable to reduce it as much as possible.

For example, patent document 1 proposes to use a polar anisotropic ring magnet whose magnetization direction is controlled to a specific direction, thereby suppressing cogging torque.

< Prior Art document >

< patent document >

Patent document 1: japanese patent laid-open publication No. 2005-44820

Disclosure of Invention

< problems to be solved by the present invention >

Conventionally, various permanent magnets have been proposed to suppress cogging torque.

However, even in a motor having a conventional permanent magnet, it is hard to say that a sufficient cogging torque suppression effect is obtained, and measures for further suppressing the cogging torque are still desired.

In view of such a background, an object of the present invention is to provide a motor and a motor assembly capable of further suppressing cogging torque. In addition, the invention aims to provide a driving device with the motor or the motor group.

< means for solving the problems >

In the present invention, there is provided a plurality of commercially available motor products, each of which includes at least 30 magnets, each of which has a porosity of 7% or less, each of which is a sintered magnet having a non-parallel oriented region and has a first main surface having a maximum peak value of surface magnetic flux density, wherein when the surface magnetic flux density on a measurement line is measured on the first main surface of each of the magnets, variation P between the magnets expressed by the following equation is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

Wherein, when a cross section of the region where the non-parallel orientation is observed is referred to as a specific cross section, the measurement line represents a measurement trajectory corresponding to the entire first main surface along a direction parallel to the specific cross section at substantially the center of the first main surface, and is set at a spatial position 1mm above the first main surface, a_totalThe total average surface magnetic flux density is expressed, and the average value of the absolute values of the surface magnetic flux densities at the same measurement position on the measurement line in each sintered magnet is obtained and taken as B_ave[mT]By calculating the average B of all the measured positions on the line_ave[mT]To sum up to obtain A_total，σ_totalRepresents the total standard deviation, and is calculated based on the total average surface magnetic flux density A on the measurement line of each sintered magnet_totalAs a standard deviation of the surface magnetic flux density at each measurement positionσ[mT]By calculating the standard deviation σ [ mT ] at all measurement positions on the measurement line]To sum up to find sigma_total。

In addition, the present invention provides a motor including a plurality of magnets, each of the magnets being a sintered magnet having a non-parallel oriented region and having a first main surface having a maximum peak value of surface magnetic flux density, wherein when the surface magnetic flux density on a measurement line is measured on the first main surface of each of the magnets, variation P between the magnets expressed by the following equation is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

In addition, the present invention provides a series of motor groups each including a plurality of motors, each of the motors including a magnet, each of the magnets being a sintered magnet having a non-parallel oriented region and having a first main surface having a maximum peak value of surface magnetic flux density, wherein when the surface magnetic flux density on a measurement line is measured on the first main surface of each of the magnets, variation P between the magnets represented by the following formula is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

In addition, in the present invention, there is provided a drive device including a motor or a motor group having the above-described features.

Further, the present invention provides a magnet group including a plurality of magnets, each magnet having a porosity of 7% or less, each magnet being a sintered magnet having a region of non-parallel orientation and having a first main surface having a maximum peak value of surface magnetic flux density, wherein when the surface magnetic flux density on a measurement line is measured on the first main surface of each magnet, variation P between magnets represented by the following formula is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

In the present invention, the porosity of each magnet is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less.

In the present invention, the variation P [% ] between magnets is preferably 3% or less, and more preferably 2% or less.

< effects of the invention >

The present invention can provide a motor and a motor assembly that can further suppress cogging torque. In addition, in the present invention, a driving device having the motor or the motor group can be provided.

Drawings

Fig. 1 is a view schematically showing a cross section of a motor in one embodiment of the present invention.

Fig. 2 is a view schematically showing an example of a sintered magnet mounted on the motor shown in fig. 1.

Fig. 3 is a view schematically showing a cross section along line S1-S1 of the sintered magnet in fig. 2.

Fig. 4 is a diagram schematically showing the surface magnetic flux density distribution on each of the first main surface and the second main surface in the sintered magnet having the polar anisotropy orientation of the easy magnetization axis.

Fig. 5 is a diagram schematically showing an operation for specifying a measurement start end portion on a measurement line in a rectangular parallelepiped sintered magnet.

Fig. 6 is a view schematically showing an operation for specifying a measurement start end portion on a measurement line in a rectangular parallelepiped sintered magnet.

Fig. 7 is a view schematically showing a cross section of a motor in another embodiment of the present invention.

Fig. 8 is a view schematically showing an example of a sintered magnet mounted on the motor shown in fig. 7.

Fig. 9 is a view schematically showing a cross section of the sintered magnet shown in fig. 8.

Fig. 10 is a diagram schematically showing an operation for specifying a measurement start point and a measurement direction on a measurement line in the annular sintered magnet.

Fig. 11 is a view schematically showing an operation for specifying a measurement start point and a measurement direction on a measurement line in the ring-shaped sintered magnet.

Fig. 12 is a diagram for explaining a method of determining parallel alignment/non-parallel alignment by the EBSD method.

Fig. 13 is a view schematically showing a cross section perpendicular to the axial direction of the IPM motor.

Fig. 14 is a view schematically showing a cross section parallel to the moving direction of the linear motor.

Fig. 15 is a diagram schematically showing a motor group in one embodiment of the present invention.

Fig. 16 is a view schematically showing a cross section of an inner rotor type rotary motor in which a magnet rotates.

Fig. 17 is a view schematically showing a cross section of an outer rotor type rotary motor in which a coil rotates.

Fig. 18 is a view schematically showing a cross section of an outer rotor type rotary motor in which a magnet rotates.

Fig. 19 is a view schematically showing a cross section of an inner rotor type rotary motor in which a coil rotates.

Fig. 20 is a view schematically showing a cross section of a cored moving coil type linear motor.

Fig. 21 is a view schematically showing a cross section of a moving magnet type linear motor having a core.

Fig. 22 is a view schematically showing a cross section of a coreless moving-coil linear motor.

Fig. 23 is a view schematically showing a cross section of a coreless moving-magnet linear motor.

Fig. 24 is a diagram schematically showing an example of a flow of a method for manufacturing a sintered magnet applied to a motor in one embodiment of the present invention.

Fig. 25 is a view schematically showing one configuration of a jig that can be used for the pressure sintering process of the ring-shaped calcined body.

Fig. 26 is a diagram schematically showing the shape of the sintered magnet produced in example 1.

Fig. 27 is a graph collectively showing the measurement results of the surface magnetic flux density of each sintered magnet produced in example 1.

Fig. 28 is a graph collectively showing the measurement results of the surface magnetic flux density of each sintered magnet produced in example 2.

Fig. 29 is a graph collectively showing the measurement results of the surface magnetic flux density of each sintered magnet produced in example 3.

Fig. 30 is a graph collectively showing the measurement results of the surface magnetic flux density of each sintered magnet produced in example 4.

Fig. 31 is a diagram showing an example of an image obtained when measuring the voids of the sintered magnet in the example.

Fig. 32 is a diagram schematically showing the shape of the sintered magnet used in example 11.

Fig. 33 is a diagram showing an example of an image obtained when measuring the voids of the sintered magnet in the comparative example.

Fig. 34 is a diagram schematically showing the shape of a sintered magnet used in example 12.

Fig. 35 is a diagram showing an example of an image obtained when measuring the voids of the sintered magnet in the comparative example.

Fig. 36 is a diagram schematically showing the structure of an apparatus for simulation.

Fig. 37 is a schematic enlarged view of a portion surrounded by a thick frame of fig. 36.

Fig. 38 is a graph showing the correlation of inter-magnet variation P and cogging torque magnitude Δ T obtained by simulation.

Fig. 39 is a diagram showing the shape and size of a motor for simulation in the 4 th device.

Fig. 40 is a graph showing the relationship between the magnet variation unevenness P and the average value of the harmonic amplitude ratio obtained by the simulation in the 4 th device.

Fig. 41 is a diagram schematically showing focal coordinates for simulation in the 5 th apparatus.

Fig. 42 is a diagram showing the shape and size of a motor for simulation in the 5 th device.

Fig. 43 is a graph showing a relationship between the magnet variation unevenness P and the average value of the harmonic amplitude ratio obtained by the simulation in the 5 th device.

Detailed Description

An embodiment of the present invention will be described below with reference to the drawings.

In the following description, the "first main surface" of the magnet refers to a surface of the magnet on which a surface magnetic flux density having a "maximum" peak is obtained. The "second main surface" of the magnet means a surface located on the opposite side of the first main surface. The "thickness" of the magnet means a distance between the first main surface and the second main surface.

In the surface magnetic flux density, the peak value "maximum" means that the peak value is farthest from 0 (zero) as a reference, regardless of the positive or negative value of the peak value.

(Motor in one embodiment of the present invention)

Fig. 1 schematically shows a cross section of a motor in an embodiment of the present invention.

As shown in fig. 1, a motor (hereinafter referred to as "first device") 101 according to an embodiment of the present invention includes a rotor 112 provided so as to be rotatable around a shaft 110, and a stator 114 surrounding the rotor 112. On the stator 114, a predetermined number of turns of the coil 118 is provided at a predetermined position.

The rotor 112 has a plurality of sintered magnets 120. For example, in the example shown in fig. 1, the rotor 112 has a total of 4 sintered magnets 120. The number of the sintered magnets of the rotor 112 is not particularly limited as long as it is plural. For example, the rotor 112 may have an even number of sintered magnets 120.

Fig. 2 schematically shows an example of the shape of the sintered magnet 120 mounted on the first device 101.

In the example shown in fig. 2, the sintered magnet 120 has a substantially rectangular parallelepiped shape. That is, the sintered magnet 120 has a first surface 130 and a second surface 132 opposed to each other, and 4 sides connecting the two

surfaces

130, 132. The 4 sides are referred to as a first side 136, a second side 137, a third side 138, and a fourth side 139, respectively, in the counterclockwise direction.

Here, the first surface 130 is a first main surface, and the second surface 132 is a second main surface. That is, it is assumed that the sintered magnet 120 obtains the maximum surface magnetic flux density on the first surface 130.

As shown in fig. 2, each surface of the sintered magnet 120 is associated with 3 orthogonal axes (XYZ axes).

That is, the first and

second surfaces

130, 132 are parallel to the XY plane, the first and

third sides

136, 138 are parallel to the XZ plane, and the second and

fourth sides

137, 139 are parallel to the YZ plane.

The dimension L of the first surface 130 and the second surface 132 in the X direction is referred to as the "length" of the sintered magnet 120, and the dimension W of the first surface 130 and the second surface 132 in the X direction is referred to as the "width" of the sintered magnet 120 "

In addition, according to the above definition, the distance between the first surface 130 and the second surface 132, i.e., the dimension t in the Z direction of each of the side surfaces 136 to 139 is the "thickness" of the sintered magnet 120.

Here, the sintered magnet 120 is configured by sintering magnet material particles. Each of the magnet material grains has an easy magnetization axis.

Fig. 3 schematically shows a cross section along the line S1-S1 in fig. 2, i.e., a cross section in a direction parallel to the XZ plane at substantially the center of the width W of the sintered magnet 120.

In fig. 3, each line segment in the cross section 160 indicates the orientation direction of the magnetization easy axis of the magnet material particle. In addition, the arrows of the line segments indicate the magnetization directions.

As shown in fig. 3, a cross section 160 of the sintered magnet 120 has a region 162 where the easy magnetization axis of the magnetic material grains is oriented "polar anisotropy".

Here, the "polar anisotropy orientation of the magnetization easy axis" of the permanent magnet means an orientation of the magnetization easy axis that causes a difference of 2 times or more in the maximum surface magnetic flux density between the first main surface and the second main surface of the permanent magnet. For example, the "polar anisotropic orientation of the magnetization easy axis" of the permanent magnet includes a configuration in which the magnetization easy axes of the magnet material particles are aligned in a predetermined direction with a gradual change.

This feature will be described in more detail with reference to fig. 4.

Fig. 4 schematically shows the surface magnetic flux density distribution on each of the first main surface and the second main surface in the sintered magnet having the polar anisotropy orientation of the easy magnetization axis. The measurement position (horizontal axis) is a direction perpendicular to the width direction of the permanent magnet.

As shown in fig. 4, the permanent magnet having the polar anisotropy orientation of the easy magnetization axis has the following features: although the surface magnetic flux density distribution having a peak larger than that of the other surface is obtained on the first main surface, the surface magnetic flux density distribution is not obtained on the second main surface. That is, a surface magnetic flux density distribution having a large difference is obtained on the first main surface and the second main surface.

In the surface magnetic flux density distribution shown in fig. 4, the area enclosed by the surface magnetic flux density curve obtained on the first main surface and the horizontal axis is represented by P₁. In addition, an area enclosed by a surface magnetic flux density curve obtained on the second main surface and a horizontal axis is represented as P₂. In a typical permanent magnet in which the magnetization easy axis is oriented by polar anisotropy, the following characteristics are provided: ratio P₁/P₂Is 2 or more, for example, 3 or more.

On the other hand, in the sintered magnet 120, the polar anisotropic alignment region 162 shown in fig. 3 does not need to be present in all cross sections parallel to the thickness direction, but may be present in at least one cross section among cross sections parallel to the thickness direction. Hereinafter, the cross section of the region 162 in which the polar anisotropic orientation is observed is also referred to as a "specific cross section".

For example, in the case of the sintered magnet 120, in fig. 2, a region 162 in which the polarity anisotropy is oriented as shown in fig. 3 is observed in a cross section parallel to the X direction of the sintered magnet 120. Therefore, a cross section parallel to the X direction (XZ plane) is a specific cross section. Note, however, that in a cross section parallel to the Y direction (YZ plane) of the sintered magnet 120, a region in which the polar anisotropy is oriented is not observed, and the cross section in this direction is not a specific cross section.

When the specific cross section is defined in this manner, the "length L" may be defined as a dimension of a connection portion connecting the first main surface and the specific cross section in the sintered magnet 120 having a substantially rectangular parallelepiped shape. The "width W" may be defined as a dimension in a direction perpendicular to the direction of the length L and perpendicular to the direction of the thickness t.

Referring again to fig. 2, each sintered magnet 120 mounted on the first device 101 has the following features: when the surface magnetic flux density is measured in a region from one end to the other end of the sintered magnet 120 along a direction (X direction in fig. 2) parallel to the specific cross section at substantially the center in the width direction of the first main surface (i.e., the first surface 130), the magnet-to-magnet variation P represented by the following formula (1) is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT]) X 100 formula (1)

In the present application, the measurement trajectory along the entire first main surface in the direction parallel to the specific cross section at the substantially center of the first main surface of the sintered magnet 120 in the width direction is referred to as a "measurement line".

In addition, in the formula (1), A_total[mT]The total average surface magnetic flux density is shown. The total average surface magnetic flux density A_total[mT]By taking the average of the absolute values of the surface magnetic flux densities at the same measurement position on the measurement line in each sintered magnet 120 as B_ave[mT]Then, the average value B at all measurement positions on the measurement line is calculated_ave[mT]The sum of the above-mentioned components.

Further, σ_total[mT]Indicates the aggregate standard deviation. The total standard deviation sigma_total[mT]By calculating the total average surface magnetic flux density A on the measurement line in each sintered magnet 120_total[mT]The standard deviation of the surface magnetic flux density at each measurement position of (1) is defined as [ mu ] mT]Then, the standard deviation σ [ mT ] at all measurement positions on the measurement line is calculated]The sum of the above-mentioned components.

For example, in the example shown in fig. 2 and 3, since the first surface 130 of the sintered magnet 120 is a first main surface and the XZ plane is a specific cross section, the measurement line is a straight line portion parallel to the X direction from the second side surface 137 to the fourth side surface 139 (or the opposite direction thereto) at the substantially center of the first surface 130 in the width direction.

In addition, the total average surface magnetic flux density A_total[mT]The absolute value of the surface magnetic flux density was measured at the same position on the measurement line in 4 sintered magnets 120, and the average value B at that position was calculated from the absolute value_ave[mT]The above-described procedure is carried out at all positions on the measurement line, and the resulting average value B is calculated_ave[mT]The sum of the above-mentioned components.

Likewise, the standard deviation σ is summed_total[mT]The average value B is obtained by using 4 sintered magnets 120_ave[mT]And the quasi-deviation sigma [ mT ] is calculated at each measurement position on the selected measurement line]The above-described steps are carried out at all positions on the measurement line, and the obtained quasi-deviation σ [ mT ] is calculated]The sum of the above-mentioned components.

Note that, if the measurement line is selected so as to be in direct contact with the first main surface of the sintered magnet 120, it may be difficult to accurately evaluate the surface magnetic flux density due to the shape of the first main surface. Therefore, in the present application, the measurement line is selected as a space 1mm above the first main surface of the sintered magnet 120.

The measurement sites on the measurement line are preferably spaced at regular intervals, and in this case, the interval between the measurement sites at 2 adjacent spots is 4 μm.

The inter-magnet variation unevenness P [% ] represented by the formula (1) can be used as an index for representing the unevenness of magnetic characteristics in the plurality of sintered magnets 120 used in the motor. That is, it can be said that the smaller the P value, the smaller the variation in characteristics among the sintered magnets 120 used.

As described above, in the conventional motor, there is a problem that it is difficult to sufficiently suppress the cogging torque.

In contrast, as described above, the sintered magnet 120 mounted on the first device 101 has a feature of suppressing the variation P represented by the formula (1) to 4% or less.

When the sintered magnet 120 having such a feature is used, variation in characteristics between magnets is significantly suppressed, and cogging torque of the motor can be significantly suppressed. Therefore, in the motor having the plurality of sintered magnets 120, vibration and noise can be significantly suppressed.

In the measurement of the surface magnetic flux density, if the measurement starting end and the measurement direction on the measurement line are not defined in each sintered magnet 120, the obtained data may not be compared with each other. In this case, the inter-magnet variation P cannot be accurately evaluated.

For example, in a normal case, it is not possible to compare the surface magnetic flux density data measured with respect to the measurement line in the direction from second side surface 137 to fourth side surface 139 with the surface magnetic flux density data measured with respect to the measurement line in the direction from fourth side surface 139 to second side surface 137 as it is. In addition, it is difficult to distinguish the difference between the second side surface 137 and the fourth side surface 139 of each sintered magnet 120 only by visually recognizing each sintered magnet 120.

Therefore, in the present application, the measurement starting end portion and the measurement direction of the sintered magnet 120 are defined as shown in fig. 5 and 6 below. Fig. 5 and 6 schematically show the operation steps in determining the measuring direction, i.e. measuring the starting end.

First, the surface magnetic flux density of each sintered magnet 120 is measured from an arbitrarily determined measurement start end portion to an opposite end portion along a measurement line. Thus, the relationship between the measurement position (horizontal axis) and the surface magnetic flux density (vertical axis) shown in fig. 5 (hereinafter referred to as "acquisition data") was obtained for each sintered magnet 120. Here, the measurement direction is assumed to be from end 1 to end 2.

Next, as shown in fig. 6, data obtained by converting the surface magnetic flux density into an absolute value (hereinafter referred to as "absolute value data") is obtained as the acquired data. The absolute value data can be obtained by folding the measurement results shown in fig. 5 along the X axis.

Then, in the absolute value dataDetermining the maximum peak value P_max. In addition, the maximum peak value P of the distance is selected in the end 1 and the end 2_maxThe one closer to the other and used as the starting end of the measurement. For example, in the example shown in the figure, the end 1 is the measurement starting end.

When there are 2 or more peak values having the same maximum value, the area surrounded by the peak value and the X axis is obtained for each peak value, and the larger area is defined as the maximum peak value P_max。

In addition, a maximum peak value P is also contemplated_maxIs exactly equidistant from end 1 and end 2. In this case, the maximum peak value P is obtained_maxI.e., the area of the region surrounded by the absolute value data and the X-axis from the center between the end 1 and the end 2 to each end. An end included in an area of the larger of the area of the region including the end 1 and the area of the region including the end 2 is determined as a measurement starting end.

Next, the direction from the measurement start end portion to the other end portion is determined as the measurement direction of the surface magnetic flux density.

The acquired data is converted based on the measurement start end portion and the measurement direction thus determined, and converted data is obtained.

When the conversion data thus obtained is used, the measurement starting end and the measurement direction can be aligned for each sintered magnet 120. In addition, this enables accurate evaluation of the magnet-to-magnet variation P.

In this way, the measurement direction for measuring the surface magnetic flux density is determined for each sintered magnet 120.

(other characteristics of the sintered magnet 120)

The sintered magnet 120 used in the first apparatus 101 is not particularly limited, and may be, for example, a rare earth sintered magnet.

In this case, the sintered magnet 120 may include R (R is 1 or 2 or more of rare earth elements including Y), B (boron), and Fe (iron). The content of each component may be, for example, 27% by weight to 40% by weight (preferably 28% by weight to 35% by weight, more preferably 28% by weight to 33% by weight) of R, and 0.6% by weight to 2% by weight (preferably 0.6% by weight to 1.2% by weight, more preferably 0.6% by weight to 1.1% by weight) of B.

The sintered magnet 120 may be, for example, an Nd-Fe-B magnet.

In order to improve the magnetic properties, the sintered magnet 120 may contain a small amount of other elements such as Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, and/or Mg, and inevitable impurities.

The size of the sintered magnet 120 is not particularly limited, and the length L may be, for example, in the range of 5mm to 40 mm. The width W of the sintered magnet 120 may be in the range of 10mm to 150 mm. The thickness t of the sintered magnet 120 may be in the range of 1.5mm to 8 mm.

(Motor in another embodiment of the present invention)

Next, a motor according to another embodiment of the present invention will be described with reference to fig. 7.

Fig. 7 is a cross section schematically showing a motor in another embodiment of the present invention.

As shown in fig. 7, a motor (hereinafter referred to as "second device") 201 includes a rotor 212 provided to be rotatable around a shaft 210, and a stator 214 surrounding the rotor 212. On the stator 214, a predetermined number of turns of the coil 218 is provided at a predetermined position.

The rotor 212 has a plurality of sintered magnets 220. For example, although it is difficult to visually recognize from fig. 7, in the second device 201, the rotor 212 has a total of 4 sintered magnets 220 in the axial direction of the shaft 210. The number of the sintered magnets of the rotor 212 is not particularly limited as long as it is plural. For example, the rotor 212 may have an even number of sintered magnets 220.

Fig. 8 schematically shows an example of the shape of the sintered magnet 220 mounted on the second device 201.

In the example shown in fig. 8, the sintered magnet 220 is substantially annular in shape. That is, the sintered magnet 220 has a first surface 230 and a second surface 232 opposite to each other, and an outer side surface 236 and an inner side surface 237 connecting the two

surfaces

230, 232.

Here, the outer side surface 236 serves as a first main surface, and the inner side surface 237 serves as a second main surface. That is, it is assumed that the sintered magnet 220 obtains the maximum surface magnetic flux density on the outer side surface 236.

Here, as shown in fig. 8, the sintered magnet 220 is associated with 3 orthogonal axes (XYZ axes). That is, first surface 230 and second surface 232 are parallel to the XZ plane, and lateral side 236 and medial side 237 extend parallel to the Y direction.

The dimension between lateral side 236 and medial side 237 is thickness t, as defined above. In addition, in the sintered magnet 220, the distance W between the first surface 230 and the second surface 232 is defined as "width"

Fig. 9 schematically shows a cross section in a direction parallel to the XZ plane at substantially the center of the width W of the sintered magnet 220.

In fig. 9, each line segment in the cross section 260 indicates the orientation direction of the magnetization easy axis of the magnet material particle. In addition, the arrows of the line segments indicate the magnetization directions.

As shown in fig. 9, a cross section 260 of the sintered magnet 220 has a region 262 in which the magnetization easy axis of the magnetic material grains is oriented "polar anisotropy". As described above, the cross section of the region 262 where the polar anisotropy orientation is observed is particularly referred to as a "specific cross section".

As can be seen from fig. 9, the particular cross-section is parallel to the XZ plane.

When the specific cross section is defined as described above, in the substantially annular sintered magnet 220, the "connecting portion" is a portion (the outer periphery of the first surface 230 or the second surface 232) connecting the first main surface and the specific cross section. In addition, "width W" may also be defined as a dimension in a direction perpendicular to the connecting portion and perpendicular to the direction of thickness t.

Each sintered magnet 220 mounted on the second device 201 has the following features: when the surface magnetic flux density is measured on the "measurement line" at substantially the center in the width direction of the first main surface (i.e., the outer surface 236), the variation P between magnets expressed by the following formula (1) is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT]) X 100 formula (1)

As described above, the "measurement line" refers to a measurement locus on the entire first main surface along a direction parallel to the specific cross section.

Therefore, in the example shown in fig. 8 and 9, the measurement line in the sintered magnet 220 is one turn (more precisely, the outer periphery at a distance of 1mm from the outer side surface 236) of the outer periphery of the sintered magnet 220 along the plane parallel to the XZ plane at the substantially center of the outer side surface 236 in the width direction.

In addition, the total average surface magnetic flux density A_total[mT]And the sum of standard deviations σ_total[mT]Is as defined above.

Therefore, in the example shown in fig. 8 and 9, the total average surface magnetic flux density a of the sintered magnet 220_total[mT]The absolute value of the surface magnetic flux density was measured at the same position on the measurement line in 4 sintered magnets 220, and the average value B at that position was calculated from the absolute value_ave[mT]The above-described procedure is carried out at all positions on the measurement line, and the resulting average value B is calculated_ave[mT]The sum of the above-mentioned components.

Likewise, the standard deviation σ is summed_total[mT]The average value B is obtained by using 4 sintered magnets 220_ave[mT]And the quasi-deviation sigma [ mT ] is calculated at each measurement position on the selected measurement line]The above-described steps are carried out at all positions on the measurement line, and the obtained quasi-deviation σ [ mT ] is calculated]The sum of the above-mentioned components.

However, as described above, the actual measurement line is set to a spatial position 1mm above the first main surface.

The measurement sites on the measurement line are preferably spaced at regular intervals. In this case, the measurement sites of the adjacent 2 points are selected so that the central angle around the center C (see fig. 9) of the specific cross section of the sintered magnet 220 is 0.04 °.

The inter-magnet variation unevenness P [% ] represented by the formula (1) can be used as an index for representing the unevenness of magnetic characteristics in the plurality of sintered magnets 220 used in the motor. That is, it can be said that the smaller the P value, the smaller the variation in characteristics among the sintered magnets 220 used.

Therefore, in the motor having the plurality of sintered magnets 220, vibration and noise can be significantly suppressed.

In the measurement of the surface magnetic flux density, if the starting point and the direction of measurement on the measurement line are not defined in each sintered magnet 220, the obtained data may not be compared with each other. In this case, the inter-magnet variation P cannot be accurately evaluated.

Therefore, in the present application, as shown in fig. 10 and 11 below, the starting point and the direction of measurement on the measurement line of the sintered magnet 220 are defined. Fig. 10 and 11 schematically show the operation steps in determining the measurement start point and the measurement direction.

First, the surface magnetic flux density of each sintered magnet 220 is measured in an arbitrary direction from an arbitrarily determined measurement start point along a measurement line. As a result, the relationship between the mechanical angle (horizontal axis) and the surface magnetic flux density (vertical axis) (hereinafter referred to as "acquired data") shown in fig. 10 was obtained for each sintered magnet 220.

Next, as shown in fig. 11, data obtained by converting the surface magnetic flux density into an absolute value (hereinafter referred to as "absolute value data") is obtained as the acquired data. The absolute value data can be obtained by folding the measurement results shown in fig. 10 along the X axis.

Next, the maximum peak value P is determined in the absolute value data_max. In addition, at the determined maximum peak value P_maxTo determine the maximum peak value P_maxThe closest 2 peaks are respectively taken as the first peak P₁And a second peak value P₂. In addition, a first peak value P is selected₁And a second peak value P₂The larger of them is taken as the specific approaching peak value P_n. For example, in the example shown in the figure, the first peak value P₁Is specifically close to the peak value P_n。

It should be noted thatWhen the maximum value is equal to more than 2 peak values, the area enclosed by the X axis is obtained for each peak value, and the larger area is used as the maximum peak value P_max。

Then, to locate at a specific approximate peak value P_nAnd maximum peak value P_maxThe position where the surface magnetic flux density becomes zero is taken as a measurement starting point of the surface magnetic flux density. In addition, the maximum peak value P is measured from the measurement starting point_maxThe direction of (2) is taken as the measurement direction.

The acquired data is converted based on the measurement start point and the measurement direction thus determined, and converted data is obtained.

When the conversion data thus obtained is used, the measurement starting point and the measurement direction on the measurement line can be aligned for each sintered magnet 120. In addition, this enables accurate evaluation of the magnet-to-magnet variation P.

In the sintered magnet, the first main surface may not be substantially flat or substantially circular. In this case, a trajectory capable of more stably evaluating the surface magnetic flux density among the linear trajectories and the circumferential trajectories is selected as the measurement line.

(other features of the sintered magnet 220)

The material and the like of the sintered magnet 220 used in the second apparatus 201 are the same as those of the sintered magnet 120 described above.

The size of the sintered magnet 220 is not particularly limited, and the width W may be, for example, in the range of 10mm to 150 mm. The sintered magnet 220 may have an outer diameter in the range of 8mm to 60mm, for example. The thickness t of the sintered magnet 220 may be in the range of 1.5mm to 6 mm.

The features of the embodiment of the present invention have been described above by taking the square sintered magnet 120 and the ring-shaped sintered magnet 220 as examples. However, the shape of the magnet used in the present invention is not particularly limited. In another embodiment of the present invention, for example, the ring-shaped sintered magnet 220 may be divided into 2, 3, 4 or more parts, and a sectorized (segment) sintered magnet may be used.

In the above examples, one feature of the present invention is explained by taking the

motor

101 or 201 including the

sintered magnet

120 or 220 having polar anisotropy as an example.

However, the magnet used in the motor in the present invention is not limited to a sintered magnet having polar anisotropy. That is, in the present invention, any sintered magnet having a region of "non-parallel orientation" may be used as long as the magnet-to-magnet variation P obtained by the above formula (1) is 4% or less.

Here, the non-parallel orientation means an orientation other than the parallel orientation. Specifically, the non-parallel orientation refers to all orientations having regions whose crystal orientations differ by 20 ° or more. The non-parallel orientation includes, for example, polar anisotropic orientation, radial orientation, and the like.

In the above description, the "specific cross section" is defined as the

cross section

160 or 260 of the

region

162 or 262 having the polar anisotropy orientation. However, hereinafter, the section of the region having an orientation other than the parallel orientation is broadly defined as a "specific section", and is not limited to the polar anisotropic orientation.

Therefore, the "magnet having a region of non-parallel orientation" refers to a magnet having a region of a "specific cross section" in which crystal orientations differ by 20 ° or more.

In addition, an EBSD (Electron Back Scatter Diffraction Patterns) method can be used to determine whether a sintered magnet has regions with non-parallel orientation.

Hereinafter, a method for determining the parallel alignment/non-parallel alignment by the EBSD method will be described specifically with reference to fig. 12.

Fig. 12 shows a cross section AP perpendicular to the first main surface of the sintered magnet in a substantially rectangular parallelepiped shape. The cross section AP is a cross section parallel to the moving direction of the motor and is a direction perpendicular to the first main surface.

The determination of whether the profile AP has regions of non-parallel orientation is made using the following method:

(i) on the cross section AP, a line segment (hereinafter referred to as "dividing line CL") connecting substantially the center in the thickness (t) direction is determined.

(ii) Each point (hereinafter referred to as "point CP") where the dividing line CL is divided into 8 equal parts is determined.

(iii) At each point CP, the orientation vector of the easy magnetization axis (direction of highest frequency) was measured in a region of 100 μm × 100 μm by the EBSD method. The measurement region is appropriately selected according to the size of the magnet material particles forming the sintered magnet. If more than 30 particles of the magnet material are measured in each field of view, the orientation vector of the easy axis can be determined.

(iv) The orientation vectors at all points CP are compared, and when the largest angle difference is 20 ° or more, it is determined that the cross section is a specific cross section and has a region of non-parallel orientation.

The above method can be applied to a substantially annular sintered magnet such as the sintered magnet 220 shown in fig. 8 and 9. However, in the cross section AP, a "line segment" connecting the approximate centers in the thickness (t) direction is a "circumference". In this case, therefore, the following evaluations will be carried out:

(i') on the cross-section AP, a circle (hereinafter referred to as "dividing line CL") connecting substantially centers in the thickness (t) direction is determined.

(ii') respective points (hereinafter referred to as "points CP") at which the dividing line CL is divided into 8 equal parts are determined.

(iii') the orientation vector of the easy magnetization axis (direction of highest frequency) was measured in a region of 100. mu. m.times.100. mu.m at each point CP by the EBSD method.

(iv') comparing the orientation vectors at all the points CP, and when the largest angle difference is 20 ° or more, determining that the cross section is a specific cross section and has a region of non-parallel orientation.

By this method, the parallel orientation/non-parallel orientation in the sintered magnet can be determined.

The type of motor to which the present invention is applied is not particularly limited. The motor may be, for example, a surface magnet type motor (SPM motor), a magnet embedded type motor (IPM motor), or a linear motor.

The SPM motor has a structure in which the sintered magnet shown in fig. 7 is provided on the surface of the rotor in the rotary motor. The IPM motor has a structure in which sintered magnets in the rotary motor are embedded in the rotor. Further, the linear motor has a structure capable of linear motion.

Fig. 13 schematically shows a cross section perpendicular to the axial direction of the IPM motor. Fig. 14 schematically shows a cross section parallel to the moving direction of the linear motor.

As shown in fig. 13, IPM motor 401 includes a rotor 412 provided so as to be rotatable around shaft 410, and a stator 414 surrounding rotor 412. On the stator 414, a predetermined number of turns of the coil 418 is provided at a predetermined position.

As can be seen from fig. 13, the IPM motor 401 is greatly different from the SPM motor in that the sintered magnet 420 is embedded inside the rotor 412.

In fig. 13, the rotor 412 has 4 sintered magnets 420. However, the number of the sintered magnets 420 included in the rotor 412 is not particularly limited as long as it is plural. For example, the rotor 412 may have an even number of sintered magnets 420.

On the other hand, as shown in fig. 14, the linear motor 451 has a structure capable of linear motion.

Specifically, the linear motor 451 has a movable member 453 and a fixed member 455. The movable element 453 has a yoke 467 and a plurality of coils 468. The fixing member 455 has a base 460 and a plurality of sintered magnets 470 disposed on the base 460.

Among various motors, in an SPM motor and a linear motor, by applying an embodiment of the present invention, cogging torque can be suppressed more significantly. This is because, in the SPM motor and the linear motor, the magnetic flux generated by the sintered magnet is not affected by the electromagnetic steel sheet of the rotor but is linked with the stator.

(Motor group in one embodiment of the present invention)

Next, another embodiment of the present invention will be described with reference to fig. 15.

Fig. 15 schematically illustrates a motor pack in one embodiment of the present invention.

As shown in fig. 15, a motor group (hereinafter referred to as a "third device") 300 in one embodiment of the present invention includes a plurality of motors 301 of the same form.

For example, in the example shown in fig. 15, the third device 300 includes a total of 10 motors 301(301A, 301B, … …, 301J).

The number of the motors 301 included in the third device 300 is not particularly limited as long as it is 2 or more.

Each of the motors 301A to 301J has one sintered magnet (which is difficult to be visually recognized in fig. 15).

Although the form of the sintered magnet included in each of the motors 301A to 301J is not particularly limited, the sintered magnet may be, for example, the ring-shaped sintered magnet 220 shown in fig. 8 and 9.

In general, the specific cross section of each sintered magnet is a plane parallel to the moving direction (rotation plane) of each motor 301A to 301J.

Here, the sintered magnets included in the motors 301A to 301J are characterized in that when the surface magnetic flux density on the measurement line is measured at substantially the center in the width direction of the first main surface, the variation P between magnets represented by the following formula (1) is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT]) X 100 formula (1)

Therefore, when the sintered magnets included in the motors 301A to 301J are the above-described sintered magnets 220, the measurement line is one turn of the outer periphery of the sintered magnets 220 (to be precise, the outer periphery at a distance of 1mm from the outer side surface 236) along the plane parallel to the XZ plane at the substantially center of the outer side surface 236 of the sintered magnets 220 in the width direction.

As described above, the variation P [% ] between magnets represented by the formula (1) can be used as an index for representing variation in magnetic characteristics in each sintered magnet. That is, it can be said that the smaller the P value, the smaller the variation in characteristics between the sintered magnets used.

Therefore, in the motor group in which the motors 301A to 301J each have such a sintered magnet, vibration and noise can be significantly suppressed.

(multiple motor product in one embodiment of the invention)

Next, another embodiment of the present invention will be described.

In another embodiment of the present invention, there is provided a plurality of commercially available motor products, each of which includes 1 or 2 or more magnets, each of which has a porosity of 7% or less, each of which is a sintered magnet having a non-parallel oriented region and has a first main surface having a maximum peak value of surface magnetic flux density, wherein when the surface magnetic flux density on a measurement line is measured on the first main surface of each of the magnets, variation P between the magnets expressed by the following equation is 4% or less.

Variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

In the present application, basically, whether or not a plurality of motor products are "identical" is determined according to the model number attached to each motor product or its package.

That is, the model number of the motor product is an inherent label that the manufacturer determines in order to distinguish the various motor products, and generally, if the same model number is attached, it can be considered as the same motor product.

However, a phenomenon called demagnetization often occurs in the motor. Due to this demagnetization, the surface magnetic flux density of the magnet may change even if the model is the same. Therefore, in the present application, even if the model is the same, the induced voltage constants of the respective motor products are measured, and the consistency of the values is checked.

If the values of the induced voltage constants measured in the same measuring instrument are within a range of + -3%, it is judged that the motor products are identical to each other. The induced voltage constant of the motor product is determined by the effective value/rotational speed of the induced voltage in the case of a rotary motor and the effective value/moving speed of the induced voltage in the case of a linear motor.

On the other hand, there are often cases where the model of the motor product is unknown, such as a case where the motor product has been mounted in the drive device. In this case, whether the plurality of motor products are "the same" is determined for each type of motor product as follows.

(in the case where the motor product is a rotary motor)

When the motor product is a rotary motor, whether or not the motor products are the same is determined by evaluating the following items for each product.

It should be noted that the rotary motor is generally divided into two parts, i.e., a stator and a rotor. In addition, the rotary motor has a structure in which a magnet is provided on a rotor and a structure in which a magnet is provided on a stator. In the following description, in order to perform an expression applicable to any configuration, the side provided with the magnet is referred to as a magnetic field system, and the side provided with the coil is referred to as an armature.

[ Motor ]

Total length of motor product LA

The total length LA represents the maximum dimension in the axial direction of the motor product. However, it is a size other than a movable portion (a terminal line or the like for transmitting electric power/signals) whose shape changes.

Constant of induced voltage

Number of poles

The number of poles can be obtained by reading the period of the induced voltage waveform using an oscilloscope or the like and doubling the number of periods per one rotation of the motor shaft.

[ armature ]

Number of slots MS

The number of slots MS is determined as the number of slots for inserting the coil. However, the coreless motor and slotless motor do not require measurement.

Diameter DS of the armature at the position where the distance to the surface opposite the magnetic field system is shortest

The diameter DS is obtained by doubling the length of a line segment connecting the center of the motor shaft and the position of the armature that protrudes most toward the field system side when the armature is viewed from the motor shaft direction.

Tooth width WT (WT1, WT2)

The tooth width WT refers to the linear distance between adjacent grooves. Normally, this distance changes between the outer circumferential side and the inner circumferential side of the groove. Therefore, the linear distance between adjacent grooves on the outer circumferential side of the groove is defined as WT1, and the linear distance between adjacent grooves on the inner circumferential side of the groove is defined as WT 2. However, no measurements are required in the case of coreless motors or slotless motors.

Total number of coils NC

Presence or absence of dummy groove

"pseudo-groove" refers to a groove present on the face of the armature opposite the magnetic field system. However, no measurements are required in the case of coreless motors or slotless motors.

[ magnetic field System ]

Number of magnets

Length LM of magnet in motor axial direction

Diameter DR of the magnetic field system at the position where the distance to the surface facing the armature is shortest

The diameter DR is obtained by doubling the length of a line segment connecting the center of the motor shaft and the position of the magnetic field system that protrudes most toward the armature side when the magnetic field system is viewed from the motor shaft direction.

Fig. 16 to 19 schematically show a part of the above-described evaluation items in various types of motor products as examples.

Fig. 16 schematically shows a cross section of an inner rotor type rotary motor in which a magnet rotates. Fig. 17 schematically shows a cross section of an outer rotor type rotary motor in which a coil rotates. Fig. 18 schematically shows a cross section of an outer rotor type rotary motor in which a magnet rotates. Fig. 19 schematically shows a cross section of an inner rotor type rotary motor in which a coil rotates.

Note that, in these drawings, the symbol GM denotes a dummy trench.

(case where the motor product is a linear motor)

In the case where the motor products are linear motors, whether or not the motor products are identical is determined by evaluating the following items for each product.

The linear motor is roughly divided into two parts, i.e., a movable element and a fixed element. In addition, in the linear motor, there are a structure in which the magnet is provided on the movable element and a structure in which the magnet is provided on the fixed element. In the following description, in order to perform an expression applicable to any configuration, the side provided with the magnet is referred to as a magnetic field system, and the side provided with the coil is referred to as an armature.

[ Motor ]

Total length of motor product LA

The total length LA represents the maximum dimension of the armature in a direction perpendicular with respect to the direction of movement and parallel with respect to the opposite face of the armature to the field system of the motor product. However, it is a size other than a movable portion (a terminal line or the like for transmitting electric power/signals) whose shape changes.

Constant of induced voltage

[ armature ]

Number of slots MS

The number of grooves MS is determined as the total number of grooves that completely cover the range of the total length along the movable direction of the movable element in the movable direction. However, the coreless motor and slotless motor do not require measurement.

Spacing between coils PA

The inter-coil pitch PA is a distance size between 2 points when the center of the inter-coil distance in the moving direction is a starting point in the 1 bundle of coils forming one loop and the center of the inter-coil distance in the adjacent 1 bundle of coils forming the other loop is an ending point. However, when a plurality of identical measurement sites exist within a range that completely covers the total length in the moving direction of the movable element in the moving direction, all of them are measured and the average value thereof is taken.

Total number of coils NC

The total number NC of coils is determined as the total number of coils within a range that completely covers the total length in the moving direction of the movable element in the moving direction.

[ magnetic field System ]

Number of magnets

The number of magnets is determined to be the number of magnets that completely covers the range of the total length along the movable direction of the movable element in the movable direction.

Length LM of magnet

The length LM of the magnet indicates the dimension of the magnet in the direction perpendicular to the movable direction and parallel to the armature opposing surface to the magnetic field system. However, when a plurality of magnets are present in a range that completely covers the total length in the movable direction of the movable element in the movable direction, all of them are measured and the average value thereof is taken.

The spacing PB between the magnets

The inter-magnet pitch PB is a distance dimension between 2 points when the center of the width dimension of 1 magnet in the movable direction is a starting point and the centers of the widths of 1 adjacent magnets are final points. However, when a plurality of identical measurement sites exist within a range that completely covers the total length in the moving direction of the movable element in the moving direction, all of them are measured and the average value thereof is taken.

Fig. 20 to 23 schematically show (a part of) the above-described evaluation items in various types of linear motor products as examples.

Fig. 20 schematically shows a cross section of a cored moving coil linear motor. Fig. 21 schematically shows a cross section of a moving magnet type linear motor having a core. Fig. 22 schematically shows a cross section of a coreless moving-coil linear motor. Fig. 23 schematically shows a cross section of a coreless moving magnet type linear motor.

As described above, the items are evaluated in each motor product, and when all the items match, each motor product is determined to be the same.

However, in the above items, the total length LA of the motor product, the diameter DS of the armature, the tooth widths WT1, WT2, the length LM in the motor axial direction of the magnet, the diameter DR of the magnetic field system, the inter-coil spacing, the length LM of the magnet, and the inter-magnet spacing include dimensional errors.

Therefore, if these items are within the tolerance range (tolerance grade: coarse grade) based on JIS B0405, they are judged to be consistent with each other.

In addition, the induced voltage constants are determined to match each other if the values measured by the same measuring instrument are within a range of ± 3%.

(application example)

The motor and the motor group in one embodiment of the present invention can be applied to various driving apparatuses and the like. The driving device may be, for example, a linear motor, a rotary motor, a robot having multiple joints, or the like.

It should be noted that the present invention can be applied to magnetic application products using a magnet, such as an actuator for a Galvano scanner (Galvano scanner), a magnetic refrigeration apparatus, and the like, in addition to general driving devices such as a rotary motor and a linear motor.

(method for producing sintered magnet)

Next, an example of a method for producing a sintered magnet having the above-described features will be described with reference to fig. 24.

Fig. 24 is a flowchart schematically showing a method of manufacturing a sintered magnet.

As shown in fig. 24, the method for manufacturing a sintered magnet includes the steps of:

(1) a step (step S110) of finely pulverizing a raw material alloy for a magnet to obtain magnet material particles;

(2) a step of forming a compact containing the magnet material particles (step S120);

(3) a step (S130) of applying a part of the annular magnetic field to the compact to orient the easy magnetization axis polarity anisotropy of the magnet material particles;

(4) a step (step S140) of obtaining a calcined body by calcining the molded body;

(5) a step (S150) of obtaining a sintered body by pressurizing the sintered body while sintering the sintered body; and

(6) and a step of magnetizing the sintered body (step S160).

Hereinafter, each step will be described. In the following description, the above-described sintered magnet 120 is taken as an example to describe a method for manufacturing the same.

(step S110)

First, a raw material alloy for a magnet is finely pulverized to form magnet material particles.

The raw material alloy for magnets is, for example, neodymium iron boron alloy. The micro-pulverization treatment can be performed, for example, by a jet type pulverization device. The center particle diameter of the magnetic material particles after the fine grinding is, for example, 1 to 5 μm.

(step S120)

Next, the obtained magnet material particles are mixed with a polymer resin to form a kneaded product.

As the polymer resin, for example, a polymer having a depolymerization property can be used. Examples of such polymers include Polyisobutylene (PIB) which is a polymer of isobutylene, polyisoprene (isoprene rubber, IR) which is a polymer of isoprene, polypropylene, poly (α -methylstyrene) obtained by polymerizing α -methylstyrene, polyethylene, polybutadiene (butadiene rubber, BR) which is a polymer of 1, 3-butadiene, polystyrene which is a polymer of styrene, a styrene-isoprene block copolymer (SIS) which is a copolymer of styrene and isoprene, a butyl rubber (IIR) which is a copolymer of isobutylene and isoprene, a styrene-butadiene block copolymer (SBS) which is a copolymer of styrene, ethylene, and butadiene, a styrene-ethylene-butadiene-styrene copolymer (SEBS) which is a copolymer of styrene, ethylene, and butadiene, Styrene-ethylene-propylene-styrene copolymer (SEPS) which is a copolymer of styrene, ethylene and propylene, ethylene-propylene copolymer (EPM) which is a copolymer of ethylene and propylene, EPDM which is obtained by copolymerizing a diene monomer with ethylene and propylene, 2-methyl-1-pentene polymer resin which is a polymer of 2-methyl-1-pentene, 2-methyl-1-butene polymer resin which is a polymer of 2-methyl-1-butene, and the like.

The polymer used as the polymer resin may contain a small amount of a polymer or copolymer of a monomer containing an oxygen atom and/or a nitrogen atom (for example, polybutylmethacrylate, polymethylmethacrylate, or the like). However, polymers that do not contain oxygen and nitrogen atoms are preferred.

The polymer resin is added, for example, so that the ratio of the polymer resin to the total amount of the magnet material particles and the polymer resin (referred to as "polymer resin mixing amount") is 1 to 20 wt%. The amount of the polymer resin is preferably 2 to 15 wt%, more preferably 2 to 10 wt%, and still more preferably 3 to 6 wt%.

Next, the obtained kneaded product is molded to form a molded body.

(step S130)

Then, a part of the annular magnetic field is applied to the molded body. Thereby, the magnetization easy axis of the magnet material particles in the molded body is oriented by the polar anisotropy.

In this step, a pulsed magnetic field generating device having a multilayer coil and a large-capacity capacitor is used. The polar anisotropy orientation can be achieved by applying a magnetic field in a direction parallel to a specific cross section by momentarily flowing a current stored in a bulk capacitor through a multilayer coil. The maximum current in this case is, for example, 8kA to 16kA, and the pulse width is, for example, 0.3 msec to 10 msec. The application of the ring-shaped pulsed magnetic field may be performed a plurality of times.

The polar anisotropic orientation step is performed at a temperature at which the melt viscosity of the mixture in which the magnet material particles and the polymer resin are mixed at a temperature at which the pulsed magnetic field is applied is 900Pa · s or less, more preferably 700Pa · s or less, and particularly preferably 300Pa · s or less. By setting this to 300Pa · s or less, the degree of orientation can be set to 93% or more even if the number of times of magnetic field application is 1. In thatThen, with 243s^-1The melt viscosity was measured at a shear rate of (g), a capillary length L/capillary inner diameter D of 1/10. The strength of the applied pulsed magnetic field is preferably 2T or more, more preferably 3T or more. By performing orientation using the magnetic field intensity, the degree of orientation can be improved even for a mixture.

(step S140)

Next, the molded body is calcined to remove the polymer resin component contained in the molded body.

The calcination treatment is performed by, for example, heating the molded body to 400 to 600 ℃ in a reducing atmosphere. The reducing atmosphere may comprise hydrogen.

After the calcination treatment, a calcined body was obtained.

(step S150)

Subsequently, the calcined body is subjected to a sintering treatment to form a sintered body. The sintering treatment is performed in a state where the calcined body is pressurized.

The pressure applied to the calcined body is, for example, 3MPa to 20 MPa. The firing temperature is, for example, in the range of 700 to 1000 ℃. The direction of the pressure applied to the calcined body is perpendicular to the plane on which the specific cross section is obtained later. For example, in the sintered magnet 120 shown in fig. 2, the pressure application direction is the Y direction.

In the sintering process, for example, hot press sintering, SPS sintering, or the like can be used. In these methods, the polar anisotropic orientation of the magnet material particles obtained in the above-described step can be maintained even after sintering.

(step S160)

Next, the obtained sintered body was magnetized.

In this magnetization processing, the same apparatus as that used in step S130 can be used.

This enables production of a magnet such as the sintered magnet 120.

The above description has been made of the method of manufacturing the sintered magnet 120 having a substantially rectangular parallelepiped shape as an example. However, it will be apparent to those skilled in the art that the above-described manufacturing method can also be applied to the manufacture of the substantially annular sintered magnet 220.

In step S150, when the annular calcined body is subjected to the sintering treatment, the pressure sintering treatment is particularly preferable.

Fig. 25 schematically shows one structure of a jig that can be used for the pressure sintering process of the ring-shaped calcined body.

As shown in fig. 25, the jig 900 has a center die 910, an upper pin 920, a lower pin 930, and a center rod 940. The center die 910 is made of graphite, and the upper pin 920, the lower pin 930, and the center rod 940 are made of stainless steel.

When the pressure sintering process is performed using this jig 900, first, the annular sintered body 950 is provided inside the center die 910 in a state where the annular sintered body 950 is penetrated by the center rod 940.

Then, the whole fixture 900 is heated to a high temperature. The heating temperature is, for example, in the range of 900 to 1050 ℃.

After the calcined body 950 reaches a predetermined temperature, the calcined body 950 is pressure sintered by pressing the upper pin 920 at a predetermined pressure.

When using the jig 900, it is preferable to apply a mold release material to a portion of the jig 900 that contacts the calcined body 950 in advance. This makes it easy to take out the processed sintered magnet from the jig 900.

In particular, the mold release material is preferably a two-layer structure of the first mold release material and the second mold release material in order from the far to the near from the calcined body 950.

The first mold releasing material is used to improve the adhesion between the second mold releasing material and the constituent members of the jig 900. In addition, the second release material is used to suppress the fixation of the calcined body 950 to the member of the jig 900.

The first release material includes boron nitride particles and a resin component. The first mold release material may further comprise alumina particles. The resin component is added in a range of 15% to 25% with respect to the total weight of the first mold release material. The resin component is selected from resin components having a thermal decomposition starting temperature of 180 ℃ to 200 ℃ inclusive and a thermal decomposition finishing temperature of 250 ℃ or less. The first release material has a shear strength of 10MPa or more at room temperature.

The second release material includes boron nitride particles and a resin component. The resin component is added in a range of 2% to 10% with respect to the total weight of the second mold release material. The resin component is selected from resin components having a thermal decomposition starting temperature of 250 ℃ or higher and a thermal decomposition finishing temperature of 400 ℃ or lower. The second release material has a shear strength of 0.5MPa or less at room temperature.

The amount of the resin component and the thermal decomposition temperature of the resin component can be measured by using Discovery TGA (manufactured by TA Instruments). Specifically, in the absence of volatile solvents in the release material, the following analytical conditions were employed:

sample amount: about 10mg

Atmosphere gas: air (a)

A container: container made of platinum

Temperature program: heating from room temperature to 1000 deg.C

Temperature rise rate: 10 ℃/min

The decomposition start temperature and the decomposition end temperature were calculated with reference to JIS K7120.

Specifically, the temperature at the intersection between the base line after the start of measurement and the maximum gradient tangent of the TG curve is defined as the decomposition start temperature, and the temperature at the intersection between the maximum gradient tangent of the TG curve and the tangent of the weight reduction end region is defined as the decomposition end temperature. Further, the amount of the residue at 750 ℃ was defined as ash, and the weight loss ratio was defined as the amount of the resin component.

Further, the shear strength of the mold release material was measured by using a SAICAS DN-20 model (manufactured by DAIPLA WINTES Co.). Specifically, in the absence of volatile solvents in the release material, the following analytical conditions were employed:

the width of the blade is as follows: 1mm (Single crystal diamond)

Inclination angle: 10 degree

Horizontal velocity: 10 μm/sec

Vertical speed: 0.5 μm/sec

Under the above conditions, the sample surface was obliquely cut, and the shear strength and the peel strength were calculated from the obtained horizontal load/displacement curve according to the following formulas:

shear strength (Pa) is horizontal load (kN)/(2 × shear cross-sectional area (m)²)×cotφ)

Here, Φ is a shear angle (45 °). W is the blade width (m), d is the vertical displacement (m), and the shear cross-sectional area (m)²) Denoted by W × d.

In the case of using such a mold release material having a two-layer structure, the sliding resistance during pressure sintering is reduced, and the sintered body 950 can be sintered without causing cracks or the like. In addition, disturbance of the orientation of the calcined body 950 can be suppressed due to reduction of the sliding resistance. Therefore, the unevenness between the obtained sintered magnets can be further reduced.

In addition, by using the above-described mold release material having a two-layer structure, the possibility of contamination of the calcined body 950 with impurities is reduced. Therefore, factors that hinder sintering are eliminated, and insufficient sintering can be avoided.

Therefore, the porosity of the obtained sintered magnet can be significantly reduced.

The pressure sintering apparatus and method can be applied to a substantially rectangular parallelepiped calcined body. In this case, however, a jig without the center rod 940 shown in fig. 25 is used in the jig 900.

[ examples ]

Next, examples of the present invention will be explained.

(evaluation of variation P between magnets)

Using a sintered magnet produced by the following method, the variation P between magnets was evaluated.

(example 1)

The sintered magnet is produced by the above-described production method.

First, an Nd-Fe-B alloy (25.25 wt% Nd, 6.75 wt% Pr, 1.01 wt% B, 0.13 wt% Ga, 0.2 wt% Nb, 2.0 wt% Co, 0.13 wt% Cu, 0.1 wt% Al, and the balance Fe and other unavoidable impurities) was finely pulverized to form magnet material particles. A jet mill is used for the milling treatment. The obtained magnetic material particles had a central particle diameter of about 3 μm.

Subsequently, a styrene-butadiene block copolymer (SBS resin) and 1-octadecyne and 1-octadecene as oil components were mixed with the obtained magnet material particles to prepare a kneaded material. The mixing amount of the polymer resin was 4 parts by weight, 1.5 parts by weight of 1-octadecyne and 4.5 parts by weight of 1-octadecene per 100 parts by weight of the magnetic material particles. Then, the kneaded material was filled into a mold having dimensions of 21.2mm in length, 32mm in width, and 4.3mm in thickness, and was molded to form a molded article.

Next, a part of the annular magnetic field is applied to the molded body by the above-described method. The toroidal magnetic field is a pulsed magnetic field generated by a pulsed current. A pulse current was generated by applying a charging voltage of 1300V to a capacitor (capacity of 1000 μ F) connected to a coil in advance and discharging the capacitor. The pulse width of the pulse current was 0.7ms, and the pulse current was 12.2 kA. The temperature of the molded article after the application of the pulsed magnetic field was 120 ℃.

Thus, the easy magnetization axis of the magnet material particles contained in the compact is oriented by polar anisotropy, and the plane represented by the length and the thickness is a specific cross section.

Next, the compact was calcined at 500 ℃ in a pressurized hydrogen atmosphere of 0.8MPa to obtain a calcined body.

Next, the obtained calcined body was filled into a graphite mold. The mold was heated to 1000 ℃ under a pressure of 10MPa, and the fired body was sintered. Thus, a sintered body having a length of 21.2mm, a width of 16mm and a thickness of 4.3mm was formed. Then, the resulting mixture was polished to a size of 20mm in length, 15mm in width and 4mm in thickness.

Next, the sintered body is magnetized until the maximum magnetic flux density is substantially saturated by using the above-mentioned ring-shaped magnetic field.

Through the above steps, 10 sintered magnets (hereinafter referred to as "batch a") were produced.

Fig. 26 schematically shows the shape of the resulting sintered magnet.

As shown in fig. 26, the sintered magnet 520 has a first main surface 530 (first surface) and a specific cross section 560. In fig. 26, the magnetization direction on a specific section 560 is schematically shown.

(evaluation)

The surface magnetic flux density was measured using each of the sintered magnets included in the lot a.

A three-dimensional magnetic field vector distribution measuring apparatus (MTX-5R: IMS) was used for the measurement. As shown in fig. 26, the measurement was performed at intervals of 0.004mm along the measurement line in a horizontal plane 1mm above the first main surface 530 of the sintered magnet 520. The measurement line passes through the center of the sintered magnet 520 in the width (Y) direction and is parallel to the length (X) direction.

The sintered magnet was fixed using a nonmagnetic material and measured so as not to affect the surface magnetic flux density. The measured surface magnetic flux density is obtained by measuring a component in the normal direction with respect to the locus of the measurement line.

Fig. 27 collectively shows the measurement results obtained for 10 sintered magnets.

In fig. 27, the horizontal axis indicates each position on the measurement line, and 0 point corresponds to the center of the sintered magnet 520 in the length (X) direction.

As can be seen from fig. 27, the difference in the surface magnetic flux density characteristics of the respective magnets included in the lot a is small.

From the obtained results, the inter-magnet variation P is calculated by the above formula (1). As a result, the magnet-to-magnet variation P was about 3.3%.

(example 2)

In the same manner as in example 1, 10 sintered magnets (hereinafter referred to as "batch B") were produced, and the characteristics of each sintered magnet were evaluated.

Fig. 28 collectively shows the measurement results obtained in 10 sintered magnets included in the lot B.

As can be seen from fig. 28, the difference in the surface magnetic flux density characteristics of the respective magnets included in the lot B is small.

From the obtained results, the inter-magnet variation P is calculated using the above formula (1). As a result, the magnet-to-magnet variation P was about 3.5%.

(example 3)

In the same manner as in example 1, 10 sintered magnets (hereinafter referred to as "lot C") were produced, and the characteristics of each sintered magnet were evaluated.

Fig. 29 collectively shows the measurement results obtained in 10 sintered magnets included in the lot C.

As can be seen from fig. 29, the difference in the surface magnetic flux density characteristics of the respective magnets included in the lot C is small.

From the obtained results, the inter-magnet variation P is calculated using the above formula (1). As a result, the magnet-to-magnet variation P was about 2.6%.

(example 4)

In the same manner as in example 1, 10 sintered magnets (hereinafter referred to as "lot D") were produced, and the characteristics of each sintered magnet were evaluated.

Fig. 30 collectively shows the measurement results obtained in 10 sintered magnets included in the lot D.

As can be seen from fig. 30, the difference in the surface magnetic flux density characteristics of the respective magnets included in the lot D is small.

From the obtained results, the inter-magnet variation P is calculated using the above formula (1). As a result, the magnet-to-magnet variation P was about 2.5%.

(example 5)

A sintered magnet was produced by the following method.

First, an Nd-Fe-B alloy (Nd: 23.45 wt%, Pr: 6.75 wt%, Dy: 1.80 wt%, B: 1.01 wt%, Ga: 0.13 wt%, Nb: 0.2 wt%, Co: 2.0 wt%, Cu: 0.13 wt%, Al: 0.1 wt%, and the balance including Fe and other unavoidable impurities) was finely pulverized to form magnet material particles. A jet mill is used for the milling treatment. The obtained magnetic material particles had a central particle diameter of about 3 μm.

Subsequently, a styrene-butadiene block copolymer (SBS resin) and 1-octadecyne and 1-octadecene as oil components were mixed with the obtained magnet material particles to prepare a kneaded material. The mixing amount of the polymer resin was 4 parts by weight, 1.5 parts by weight of 1-octadecyne and 4.5 parts by weight of 1-octadecene per 100 parts by weight of the magnetic material particles. Then, the kneaded material was filled into a mold having dimensions of 29.8mm in outside diameter, 25.2mm in inside diameter, and 30mm in width (axial length), and was molded to form an annular molded body.

Next, a part of the annular magnetic field is applied to the molded body by the above-described method. The toroidal magnetic field is a pulsed magnetic field generated by a pulsed current. A pulse current was generated by applying a charging voltage of 2550V to a capacitor (capacity of 1000 μ F) connected to a coil in advance and discharging the capacitor. The pulse width of the pulse current was 0.7ms, and the pulse current was 11.9 kA. The temperature of the molded article after the application of the pulsed magnetic field was 120 ℃.

The coil is disposed outside the annular molded body so as to be parallel to the axial length direction.

Thereby, the magnetization easy axis of the magnet material particles contained in the compact is oriented by polar anisotropy. The molded body is oriented in a polar anisotropic manner so as to have 8 magnetic poles on the outer diameter side. The specific cross section of the molded body is a cross section perpendicular to the axial length direction.

Next, the obtained calcined body is subjected to pressure sintering treatment using the jig 900 shown in fig. 25.

First, a mold release material is sprayed on the center die 910, the upper pins 920, the lower pins 930, and the center rod 940 at a portion that may come into contact with the calcined body. The mold release material has a double-layer structure of the first mold release material and the second mold release material. Note that the mold release material is disposed so that the second mold release material side is in contact with the calcined body.

Subsequently, the calcined body was pressed by the upper pin 920 and the lower pin 930 at a pressure of 10.5MPa in the axial direction. In this state, the jig 900 is heated to 980 ℃ and held for 30 minutes, whereby the calcined body is sintered.

Thus, an annular sintered body having an outer diameter of 29.8mm, an inner diameter of 23.8mm and an axial length of 15mm was formed. The sintered body was heat-treated at 1000 ℃ for 7 hours, and then further heat-treated at 480 ℃.

Through the above steps, 30 sintered magnets (hereinafter referred to as "batch E") were produced.

(evaluation)

(uneven deviation between magnets P)

The surface magnetic flux density was measured by the same method as in example 1 using each of the sintered magnets included in batch E.

However, each of the sintered magnets included in lot E is annular, and the first main surface is the outer peripheral surface. Therefore, the position 1mm from the outer peripheral surface of the sintered magnet was taken as a measurement line, and the measurement was performed along the measurement line. The measurement interval was 0.04 °.

From the obtained surface magnetic flux density, the variation P between magnets was calculated by the above formula (1), and as a result, P was 3.8%.

(void fraction)

The porosity was evaluated using each sintered magnet included in batch E.

The porosity was measured by using a measuring apparatus FINE SAT III (FS200III) (manufactured by Hitachi Power Solutions, Ltd.) in the following manner.

First, a sample for measuring the porosity was prepared from a sintered magnet. The ring-shaped sintered magnet was cut in a direction parallel to the specific cross section, and a 4mm wide ring-shaped sample was obtained from a substantially central portion along the axial length direction (width W direction in fig. 8) of the sintered magnet.

Next, the sample was set in the measuring apparatus, and the measurement was performed under the following conditions and operation method.

The probe used was 50P6F15 (frequency 50MHz, focal length 16mm, working distance 15 mm). The sample was aligned with the center in the width direction, and the focal point of the probe was measured by the reflection method.

Specifically, the following operations are performed.

The Z-axis coordinate of the probe is adjusted in a manner that maximizes the surface echo. Next, the Z-axis coordinate of the probe was adjusted so as to maximize the echo from the bottom surface of the sample in a state where the detection intensity gain was fixed to 24 Hz. The distance between the probe and the sample is set to 0.2mm or more so that the probe does not contact the sample.

Next, an F-gate with a gate (gate) width of 200ns was set at the center of the surface echo and the echo from the bottom surface of the sample.

The Z-axis coordinate of the probe is adjusted to a height between the Z-axis coordinate in which the surface echo is maximum and the Z-axis coordinate of the probe in which the echo from the bottom surface of the sample is maximum, so that the sample is focused on the central portion in the width direction.

The height (trigger) of the S-gate is adjusted to the extent that it is not affected by noise. The measurement was performed at 50 μm intervals, and the scanning pattern was selected with the speed being preferred.

In addition, the energy applied to the probe was 50V, the pulse cycle frequency (PRF) was 10kHz, the high-pass filter was 10MHz, the low-pass filter was 140MHz, the depth data was the trigger point, and the surface echo detection mode was (+) (-).

The image to be displayed is a standard video (Std), and the brightness of the image displayed by the color bar is set to 6 for High, 0 for Low, and 0 for Bright.

From the obtained image, the area ratio of the voids was calculated using image analysis software (ImageJ). The portion having a luminance of 120 or more is recognized as a void.

In the process of manufacturing the sintered magnet, the outer peripheral surface and the inner peripheral surface of the sample may be affected differently. Therefore, the area ratio was calculated by excluding a portion having a depth of 500 μm from the outer peripheral surface of the sample and a portion having a depth of 500 μm from the inner peripheral surface of the sample.

As a result of the measurement, the average value of 30 voids was 3.8%.

Fig. 31 shows an example of the resulting image. It can be seen that there were fewer voids in the sintered magnets contained in lot E.

(example 6)

A sintered magnet was produced by the following method.

Next, a part of the annular magnetic field is applied to the molded body by the above-described method. The toroidal magnetic field is a pulsed magnetic field generated by a pulsed current. A pulse current was generated by applying a charging voltage of 1650V to a capacitor (capacity of 1000 μ F) connected to the coil in advance and discharging the capacitor. The pulse width of the pulse current was 0.7ms, and the pulse current was 12.5 kA. The temperature of the molded article after the application of the pulsed magnetic field was 120 ℃.

The coil is provided in parallel to the width direction of the rectangular parallelepiped molded body.

Thereby, the magnetization easy axis of the magnet material particles contained in the compact is oriented by polar anisotropy. The specific cross-section of the shaped body is the direction parallel to the plane formed by the length and thickness.

Subsequently, the obtained calcined body is subjected to pressure sintering treatment.

The pressure sintering process uses the same apparatus as the jig 900 shown in fig. 25. However, this apparatus does not have the center bar 940 of the jig 900, but is composed of a center die, an upper pin, and a lower pin.

Before the pressure sintering treatment, a mold release material is sprayed at a portion that is likely to come into contact with the calcined body. The same mold release material as in example 5 was used.

After the calcined body was set on the center die, the calcined body was pressurized by the upper pin and the lower pin at a pressure of 9.1MPa in the axial direction. In this state, the calcined body was sintered by heating the apparatus to 980 ℃ and holding it for 5 minutes.

Thus, a rectangular parallelepiped sintered body having a length of 21.2mm, a width of 16mm and a thickness of 4.3mm was formed. The sintered body was heat-treated at 1000 ℃ for 7 hours, and then further heat-treated at 480 ℃. Then, the resulting mixture was polished to a size of 20mm in length, 15mm in width and 4mm in thickness.

Through the above steps, 30 rectangular parallelepiped sintered magnets (hereinafter referred to as "batch F") were produced.

(evaluation)

(uneven deviation between magnets P)

The surface magnetic flux density was measured by the same method as in example 1 using each of the sintered magnets included in batch F. Further, based on the obtained results, the inter-magnet variation P is calculated by the above formula (1).

As a result, the variation P between magnets in the batch F was 1.9%.

(void fraction)

The porosity was evaluated by the above method using each sintered magnet included in the lot F. As a result, the average value of the void ratio in the batch F was 1.9%.

(example 11)

The same evaluation as in example 1 was performed using 5 commercially available ring-shaped sintered magnets. As the sintered magnet, a 4-polar anisotropic magnet was used.

Fig. 32 schematically shows the shape of the sintered magnet used.

As shown in fig. 32, the sintered magnet 620 has a first main surface 630 (outer peripheral surface) and a specific cross section 660 (upper surface). Fig. 32 schematically shows the magnetization direction on a specific section 660.

In the same manner as in example 1, the surface magnetic flux density was measured along the measurement line at substantially the center in the width (Y) direction of each sintered magnet 620, and the inter-magnet variation P was calculated from the obtained results. In example 11, the measurement line is a circle having a distance of 1mm from the outer peripheral surface 630 of the sintered magnet 620, and the measurement interval is 0.04 °.

As a result, the magnet-to-magnet variation P was about 4.9%. The average value of the void ratios measured by the above method was 8.1%.

Fig. 33 shows an example of the resulting image. As is apparent from fig. 33, many voids are observed in the sintered magnet 620.

(example 12)

The same evaluation as in example 1 was performed using 3 commercially available ring-shaped sintered magnets. A radial anisotropic magnet was used as the sintered magnet.

Fig. 34 schematically shows the shape of the sintered magnet used.

As shown in fig. 34, the sintered magnet 720 has a first main surface 730 (outer peripheral surface) and a specific cross section 760 (upper surface). Fig. 34 schematically shows the magnetization direction on a specific section 760. The sintered magnet 720 had an outer diameter (maximum dimension in the X direction) of 43.1mm and a thickness (distance between the outer peripheral surface and the inner peripheral surface) of 2.2 mm. Further, the width (dimension in the Y direction) was 39.2 mm.

Using the sintered magnets 720, the surface magnetic flux density was measured by the same method as in example 11, and the inter-magnet variation P was calculated from the obtained results.

As a result, the magnet-to-magnet variation P was about 7.4%.

(example 13)

The same evaluation as in example 1 was performed using 10 commercially available ring-shaped sintered magnets. A 4-pole polar anisotropic magnet was used as the sintered magnet.

The shape of the sintered magnet used was the same as that of example 11 described above.

Using the sintered magnets, the surface magnetic flux density was measured by the same method as in example 11, and the inter-magnet variation P was calculated from the obtained results.

As a result, the magnet-to-magnet variation P was about 14.3%.

The average value of the porosity of 10 sintered magnets measured by the above method was 7.3%.

Fig. 35 shows an example of the resulting image. As is apparent from fig. 35, many voids were observed in the sintered magnet.

(evaluation by simulation)

Assuming the series of motor groups (third devices) shown in fig. 15, the influence of the variation P between magnets on the cogging torque of the third device was evaluated by simulation.

Assume that the number of motors is 10, and each motor is mounted with a sintered magnet. The sintered magnet attached to each motor is a ring-shaped sintered magnet 220 having 4-polar anisotropy as shown in fig. 8 and 9.

Specifically, the following simulation was performed.

First, Δ θ, Δ D, Δ G, Δ x, and Δ y are assumed as factors that affect the unevenness of the surface magnetic flux density characteristics of 10 sintered magnets.

Here, Δ θ, Δ D, and Δ G are parameters related to characteristic unevenness generated when the magnet compact is magnetized.

Each parameter will be described with reference to fig. 36 and 37.

Fig. 36 schematically shows a device structure for simulation. Fig. 37 shows a schematic enlarged view of a portion surrounded by a thick frame of fig. 36.

As shown in fig. 36, the device 800 has a sleeve 810, a coil 818, and a yoke 870.

The sleeve 810 functions as a "die" for disposing the magnet press 821. The sleeve 810 is a ring of magnetic material and has the same center as the center H of the device 800.

Around the

sleeve

810, 4 coils 818 are provided at substantially equal intervals (intervals of about 90 °) with the center H as the rotation center.

As shown in fig. 37, there is an air region 819 between the coil 818 and the sleeve 810.

A yoke 870 is disposed around the sleeve 810 and the coil 818.

Here, as shown in fig. 37, the parameter Δ θ represents an angle formed by a horizontal straight line passing through the center H of the device 800 and the extension axis M passing through the center H of the coil 818 on the left side at the time of magnetization processing.

As shown in fig. 37, when the maximum dimension of the air region 819 existing between the coil 818 and the sleeve 810 on the left side in the direction of the extension axis M of the coil 818 is denoted as D, Δ D is expressed as Δ D ═ D-D₀. Here, D₀Which represents the desired maximum dimension of the air region 819 in the direction of the axis of extension M of the coil 818.

Δ G represents a deviation from the complete (100%) magnetization of the magnet compact due to the magnetization treatment. For example, when the ideal magnetic susceptibility is G₀Is represented as Δ G ═ G₀-G. Here, G is the actual magnetic susceptibility.

In the actual simulation, the variation in the current value flowing through the coil 818 is used as a direct input parameter, and Δ G is a quadratic parameter caused by the variation in the current value.

On the other hand, Δ x and Δ y are parameters indicating the deviation of the central axis of the sintered magnet obtained after magnetization from the central axis of an ideal sintered magnet. That is, Δ x represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the x direction, and Δ y represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the y direction.

These parameters were changed to produce variation in characteristics among the 10 sintered magnets. In addition, the fluctuation width of cogging torque generated in each motor when the value of the magnet variation P among 10 sintered magnets was varied from about 1% to about 11% was evaluated by simulation.

The simulation used electromagnetic field analysis software (JMAG-Designer: version 16.1.03 k).

The sintered magnet is a neodymium magnet.

Fig. 38 shows the evaluation results of the simulation.

In FIG. 38, the horizontal axis represents the inter-magnet variation P [% ]]. In addition, the vertical axis represents the cogging torque amplitude Δ T [ mN · m ]]. In the third device, the cogging torque amplitude Δ T [ mN · m ]]The value of cogging torque (K) in the motor generating the maximum cogging torque_max) The value of cogging torque (K) in the motor generating the minimum cogging torque_min) The difference is expressed.

As can be seen from fig. 38, if the inter-magnet variation P is smaller, the cogging torque amplitude Δ T in the third device tends to decrease. In particular, it can be seen that when the variation P ≦ 4% between magnets, the cogging torque amplitude Δ T can be suppressed to about 2.5mN · m or less.

In this way, it was confirmed that cogging torque generated in a series of motors can be significantly suppressed by setting the magnet-to-magnet variation P in the sintered magnet used for the motor to 4% or less.

(evaluation by Another simulation)

The influence of the variation P between magnets on the cogging torque was evaluated by simulation assuming a plurality of identical motor products.

It is assumed that the number of motor products is 30, and each of the motor products has a sintered magnet mounted thereon. The sintered magnet attached to each motor product is a ring-shaped sintered magnet 220 having 4-polar anisotropy as shown in fig. 8 and 9. Hereinafter, the structure used for the simulation will be referred to as "fourth device".

The following simulations were performed.

First, Δ θ, Δ D, Δ G, Δ x, and Δ y are assumed as factors that affect the unevenness of the surface magnetic flux density characteristics of 30 sintered magnets.

Here, Δ θ, Δ D, and Δ G are parameters related to characteristic unevenness generated when a compound (compound) is magnetized.

Each parameter will be described with reference to fig. 36 and 37.

The sleeve 810 functions as a "mold" for disposing the compound 821. The sleeve 810 is a ring of magnetic material and has the same center as the center H of the device 800.

Around the

sleeve

A yoke 870 is disposed around the sleeve 810 and the coil 818.

Δ G represents a deviation from the perfect (100%) magnetization of the sintered magnet due to the magnetization treatment. For example, when the ideal magnetic susceptibility is G₀Is represented as Δ G ═ G₀-G. Here, G is the actual magnetic susceptibility.

These parameters were varied to produce variation in characteristics among the 30 sintered magnets. At this time, a parent group having a small variation in surface magnetic flux density and a larger parent group are established. Further, the relationship between the magnet gap variation P between 30 sintered magnets randomly extracted from each parent group and the cogging torque generated in 30 motor products was evaluated by simulation.

The simulation was performed according to the following procedure:

I. simulation of unevenness in orientation of easy magnetization axis for a compound;

II, aiming at the simulation of unevenness of the sintered magnet during magnetization; and

simulation of cogging torque non-uniformity in motor production.

The simulation used electromagnetic field analysis software (JMAG-Designer: version 16.1.03 k). The calculations of I and II use two-dimensional static analysis, and the calculation of III uses two-dimensional transient response analysis.

Hereinafter, each item I to III will be described in detail.

(simulation of unevenness in orientation of easy magnetization axis for Compound)

An example of simulation of unevenness in the orientation of the magnetization easy axis used for the simulation will be described with reference to fig. 36.

The compound 821 has dimensions of 15mm phi in outer circumference and 5.6mm in thickness (3.8 mm phi in inner circumference). As the compound material, initial magnetization curve (B-H) data actually measured using a measuring device such as a pulse excitation type magnetic characteristic measuring device or a BH curve tracker is assigned.

The sleeve 810 is carbon steel S45C having an outer circumference of 25mm phi and an inner circumference of 7.5mm phi (thickness t of 5 mm). The yoke 870 has an outer circumference of 100mm phi and a thickness t of 37.5mm (an inner circumference of 25mm phi), and the magnetic material is SS 400. Note that, a coil 818 is present inside the yoke 870, and the coil 818 has a width of 11.2mm in parallel with a horizontal straight line or an extension axis M passing through the center H as a center line, and has a depth of 20mm in a direction perpendicular to the horizontal straight line or the extension axis M.

A round corner with a radius of 2.8mm is formed at the corner of the coil area. The number of turns is set to 52 turns per coil. The air region 819 existing between the coil 818 and the sleeve 810 has a width of 5.1mm in parallel with the horizontal straight or extended axis M of the coil 818 as a center line, and an ideal maximum dimension D in the direction of the horizontal straight or extended axis M₀Is 0.5 mm.

Using this model, the magnetization easy axis direction of the compound 821 was determined assuming that the above parameters Δ θ and Δ D were changed and a current of 20kA was applied to each coil.

(simulation of unevenness in magnetization of sintered magnet)

Next, using the same model, the compound 821 was replaced with a sintered magnet, and magnetization material data determined from a pattern in the direction of the easy axis determined in advance and the initial magnetization curve (B-H), the magnetic susceptibility, and the recovery relative permeability curve obtained by actual measurement were assigned, and the current value for applying current to the coil 818 was used as a variable parameter in addition to Δ θ and Δ D, and magnetization processing was performed, thereby producing magnet material data in which the direction of the easy axis and the magnetic susceptibility G are different.

Next, an example of the surface magnetic flux density calculation for the simulation will be described with reference to fig. 9.

The sintered magnet 220 has an outer circumference of 10.0mm phi, a width W of 25mm, and a thickness t of 2.25mm (inner circumference of 5.5mm phi), and is assigned with the magnet material data prepared by the previous magnetization process.

In addition, when distributing the magnet material data, the parameters Δ x and Δ y are changed with respect to the relative positions of the center H of fig. 36 and the center C of fig. 9, so that data of the sintered magnet 220 having different surface magnetic flux waveforms are obtained.

In the obtained sintered magnet 220, the surface magnetic flux density was measured along the measurement line, and the inter-magnet variation P was calculated from the result.

(simulation of cogging torque unevenness in motor products)

Next, the shape and size of the motor product used for the simulation will be described with reference to fig. 39.

As shown in fig. 39, the stator of the motor product had a cylindrical shape with an outer circumference of 21mm phi, an inner circumference of 10.3mm phi, and a lamination thickness of 25mm, and was disposed concentrically with the sintered magnet. In the stator, 6 slots for providing coils inside and 6 teeth for winding the coils are formed in an alternating and equiangular manner.

The depth dimension of the groove was 17mm phi, and the thickness of the tooth width at the portion from the groove depth side of the stator to the center point C was uniformly 3.1 mm.

The teeth are configured such that the width of the center-side tip is wide, and the gap between the tips of adjacent teeth is set such that the angle passing through the center point of the motor is 14 degrees. The end of the center side of the portion having a tooth thickness of 3.1mm is located on a circumference having a diameter of 12.4mm phi with the center coordinate of the motor as the center point. The side of the portion having a tooth thickness of 3.1mm was spread in the tip end direction at an angle of 137 ° with the center-side terminal end portion as a base point.

The stator is provided with 6 tooth profiles which are symmetrical with each other in the left-right direction and are equally spaced in the circumferential direction.

The stator is electromagnetic steel plate 50H700, the shaft is carbon steel S45C, and the coil is copper.

The number of turns of the coil 218 is arbitrarily set.

The setting conditions for calculating the cogging torque are as follows.

The number of analysis steps was 61 steps, and it was set that the rotor was rotated by 1 ° per step. The number of gap divisions was 4 in the radial direction and 720 in the circumferential direction. The number of elements is 34,938 and the number of nodes is 19,294.

Under this condition, sintered magnets having various surface magnetic flux densities were assigned and calculated, and the difference between the maximum peak point and the minimum peak point of the output cogging torque waveform was recorded as the cogging torque value in the motor product.

From the above calculation, 1 surface magnetic flux density and 1 cogging torque value were associated with 1 sintered magnet.

By preparing a plurality of combinations of the surface magnetic flux density and the cogging torque value and randomly selecting 30 combinations from the combinations, the relationship between the inter-magnet variation P [% ] and the cogging torque is calculated.

Fig. 40 shows the evaluation results of the simulation.

In fig. 40, the horizontal axis represents the variation P [% ]betweenmagnets. The vertical axis represents the average value of the harmonic amplitude ratio.

Here, the "average value of the harmonic amplitude ratio" is one of parameters obtained by fourier-transforming the cogging torque value in a range of 360 °.

Specifically, when fourier transforming the cogging torque value, the amplitude is separated at specific high harmonic components. If the type of motor product is assumed to be an N-pole M-slot, a peak of the amplitude is generated at the position of the number M and the position of the number expressed by the least common multiple of M and N. The former peak is due to magnet nonuniformity and is called a stator period component. On the other hand, the latter peak is due to the construction of the motor product, called the cogging fundamental.

The "high harmonic amplitude ratio" on the vertical axis is expressed as the ratio of two peaks, i.e., stator period component/slot fundamental. Therefore, the "average value of harmonic amplitude ratios" is represented by an average value of harmonic amplitude ratios in the motor product as the subject.

As can be seen from fig. 40, in the fourth apparatus, when the magnet-to-magnet variation P is 4% or less, the average value of the harmonic amplitude ratio is greatly reduced and suppressed to about 0.8 or less.

(evaluation by further simulation)

Here, however, it is assumed that the number of motor products is 30, and 4 sintered magnets are mounted on each motor product. The sintered magnets attached to the respective motor products are fan-shaped sintered magnets obtained by equally dividing the ring 4. Hereinafter, the structure used for the simulation will be referred to as "fifth device".

The following simulations were performed.

First, Δ x and Δ y are assumed as factors that affect the unevenness of the surface magnetic flux density characteristics of 4 × 30 sintered magnets.

Here, Δ x and Δ y are parameters for providing unevenness to the focal coordinates of the radial orientation. These parameters were varied to produce variations in characteristics among 4 × 30 sintered magnets. At this time, a parent group having a small variation in surface magnetic flux density and a larger parent group are established. Further, the relationship between the inter-magnet variation P between 4 × 30 sintered magnets randomly extracted from each parent group and the cogging torque generated in 30 motor products was evaluated by simulation.

The software and the like used in the simulation are the same as those in the case of the simulation in the above-described apparatus 4.

The simulation was performed according to the following procedure:

I. simulation of characteristic unevenness in the sintered magnet; and

simulation of cogging torque non-uniformity in motor production.

Hereinafter, the description will be given separately.

(simulation of Property unevenness in sintered magnet)

An example of calculation of the surface magnetic flux density used for the simulation will be described with reference to fig. 41.

As shown in fig. 41, the sintered magnet used was a sector-shaped sintered magnet obtained by equally dividing the ring 4 having an outer circumference of 19mm phi and a thickness t of 3.5mm (inner circumference of 12mm phi), and 0.4mm of the magnet portion was removed in parallel to the straight line formed by the X axis and the Y axis, and the 4 corners were chamfered at 1mm square.

In this magnet model, a center point corresponding to an outer or inner circumference of the magnet is set as origin coordinates (0,0), and focal coordinates as a reference are set at coordinates (13, 13). That is, it is assumed that the magnetization easy axis direction in the magnet is oriented in a direction converging to the coordinates (13, 13). Data of sintered magnets having different focal coordinates are generated by shifting Δ X in the X-axis direction and Δ Y in the Y-axis direction with respect to the reference coordinates.

In the data of each sintered magnet, the surface magnetic flux density was measured along the measurement line, and the inter-magnet variation P was calculated from the obtained results. Here, the measurement line in the sintered magnet is a range of 0 ° to 90 ° from the X axis to the Y axis on a concentric circle having a first main surface on a surface opposite to the focal coordinate and being separated by 1mm from the first main surface toward the focal coordinate.

(simulation of cogging torque unevenness in motor products)

Next, the shape and size of the motor product used for the simulation will be described with reference to fig. 42.

As shown in fig. 42, the stator core of the motor product had a cylindrical shape with an outer circumference of 42mm phi, an inner circumference of 20.4mm phi, and a lamination thickness of 23mm, and was disposed on a concentric circle with the sintered magnet. In the stator core, 6 slots for disposing coils inside and 6 teeth for winding the coils are formed in an alternating and equiangular manner.

The depth dimension of the groove was 34mm phi, and the thickness of the tooth width at the portion from the groove depth side of the stator to the center point C was uniformly 6.2 mm.

The teeth are configured such that the width of the center-side tip is wide, and the gap between the tips of adjacent teeth is set such that the angle passing through the center point of the motor is 14 degrees. The center side end of the portion having the tooth thickness of 6.2mm is located on a circumference having a diameter of 24.8mm phi with the center coordinate of the motor as the center point. The side of the portion having a tooth thickness of 6.2mm was spread in the tip end direction at an angle of 137 ° with the center-side terminal end portion as a base point.

The rotor is composed of a shaft located at the center of the motor product, a sintered magnet located on the outer diameter side of the rotor, and a rotor core of a magnetic material located between the shaft and the sintered magnet. The rotor core had an outer circumference of 12mm phi and an inner circumference of 6mm phi, and a total of 4 projections spaced 9mm from the motor center were provided so as to fill the gap between the sintered magnets.

The stator core and rotor core are electromagnetic steel plates 50a700, the shaft is carbon steel S45C, and the coils are copper. The number of turns of the coil 218 is arbitrarily set.

The setting conditions for calculating the cogging torque are as follows.

The number of analysis steps was 61 steps, and it was set that the rotor was rotated by 1 ° per step. The number of gap divisions was 4 in the radial direction and 720 in the circumferential direction. The number of elements is 43,395 and the number of nodes is 23,218.

Under this condition, sintered magnet patterns having various surface magnetic flux densities were assigned to the 4-point sintered magnets of the motor product and calculated, and the difference between the maximum peak point and the minimum peak point of the output cogging torque waveform was recorded as the cogging torque value in the motor product.

Note that the focal position pattern of the sintered magnet shown in fig. 41 is an example of a pattern corresponding to the sintered magnet located in quadrant 1 of the sintered magnet in the motor of fig. 42. Therefore, when the position of the sintered magnet is different from the positions of the 2 nd quadrant, the 3 rd quadrant, and the 4 th quadrant, a pattern in which the respective coordinates are rotated every 90 ° is assigned.

From the above calculations, 4 surface magnetic flux densities (4 sintered magnets) and 1 cogging torque value were associated with 1 motor product.

By preparing a plurality of combinations of the 4 surface magnetic flux densities and the cogging torque values in advance and randomly selecting 30 combinations from the combinations, the relationship between the 4 × 30 inter-magnet variation P [% ] and the cogging torque of 30 motor products was calculated.

Fig. 43 shows the evaluation results of the simulation.

In fig. 43, the horizontal axis represents the variation P [% ]betweenmagnets. The vertical axis represents the average value of the harmonic amplitude ratio.

As can be seen from fig. 43, in the fifth device, when the magnet-to-magnet variation P is 4% or less, the average value of the harmonic amplitude ratio is greatly reduced and suppressed to about 0.8 or less.

In this way, it was confirmed that cogging torque and harmonic amplitude ratios generated in a plurality of motor products can be significantly suppressed by setting the magnet-to-magnet variation P in the sintered magnet used for the motor products to 4% or less.

The present invention is not limited to the above embodiments, and various changes can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means respectively disclosed in different embodiments are also included in the technical scope of the present invention.

The present application takes Japanese invention patent application No. 2018-188967, filed on.4.10.2018, and Japanese invention patent application No. 2019-181588, filed on.1.10.2019 as the basis for claiming priority, and the entire contents of the Japanese application are incorporated herein by reference.

Description of the symbols

101 motor

110 shaft

112 rotor

114 stator

118 coil

120 sintered magnet

130 first surface

132 second surface

136 first side

137 second side surface

138 third side

139 fourth side

Section 160

Region 162

201 Motor

210 shaft

212 rotor

214 stator

218 coil

220 sintered magnet

230 first surface

232 second surface

236 outer side

237 the medial side of the body

Section 260

262 region

300 motor group

301(301A, 301B, … …, 301J) motor

401 IPM motor

410 shaft

412 rotor

414 stator

418 coil

420 sintered magnet

451 Linear motor

453 movable element

455 fixation element

467 magnet yoke

468 coil

460 base

470 sintered magnet

520 sintered magnet

530 first major face

560 specific profile

620 sintered magnet

630 first major face

660 specific profile

720 sintered magnet

730 first main face

760 specific profile

800 apparatus

810 sleeve

818 coil

819 region of air

821 blank pressing

870 magnetic yoke

900 jig

910 center die

920 Upper pin

930 lower pin

940 center rod

950 calcined body

AP Profile

CL cut line

CP Point

Claims

1. A commercially available multiple motor product of the same type,

the motor products exist more than 30,

each motor product includes 1 or more than 2 magnets,

each magnet has a porosity of 7% or less,

each magnet is a sintered magnet having a region of non-parallel orientation and has a first main surface having a maximum peak value of surface magnetic flux density,

when the surface magnetic flux density on the measurement line is measured on the first main surface of each magnet, the variation P between magnets expressed by the following formula is 4% or less,

variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

Wherein, when a cross section of the region in which the non-parallel orientation is observed is referred to as a specific cross section, the measurement line represents a measurement locus corresponding to the entire first main surface along a direction parallel to the specific cross section at substantially the center of the first main surface, and is set at a spatial position 1mm above the first main surface,

A_totalthe total average surface magnetic flux density is expressed, and the average value of the absolute values of the surface magnetic flux densities at the same measurement position on the measurement line in each sintered magnet is obtained and taken as B_ave[mT]By calculating the average B of all the measured positions on the line_ave[mT]To sum up to obtain A_total，

σ_totalRepresents the total standard deviation, and is calculated based on the total average surface magnetic flux density A on the measurement line of each sintered magnet_totalThe standard deviation of the surface magnetic flux density at each measurement position of (1) is defined as [ mu ] mT]By calculating the standard deviation σ [ mT ] at all measurement positions on the measurement line]To sum up to find sigma_total。

2. The plurality of motor products of claim 1, wherein each motor product comprises 1 magnet.

3. The plurality of motor products of claim 1, wherein each motor product comprises a plurality of magnets.

4. A motor has a plurality of magnets,

variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

5. The motor of claim 4, wherein each magnet has a void fraction of 7% or less.

6. The motor of claim 4 or 5, wherein the non-parallel orientation is a polar anisotropic orientation or a radial orientation.

7. The motor according to any one of claims 4 to 6, wherein the magnet is substantially rectangular parallelepiped shaped or substantially ring shaped.

8. A series of motor sets having a plurality of motors,

each of the motors has a magnet that is,

variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

9. The motor set as claimed in claim 8, wherein each magnet has a void ratio of 7% or less.

10. A drive arrangement having a motor according to any one of claims 4 to 7 or a motor pack according to claim 8 or 9.

11. A plurality of motor products according to any one of claims 1 to 3 taken from the same drive means.

12. A magnet set comprises a plurality of magnets,

each magnet has a porosity of 7% or less,

variation P [ ] between magnets]＝(σ_total[mT]/A_total[mT])×100

A_totalrepresents the sum averageThe surface magnetic flux density is determined as B by averaging the absolute values of the surface magnetic flux densities at the same measurement position on the measurement line in each sintered magnet_ave[mT]By calculating the average B of all the measured positions on the line_ave[mT]To sum up to obtain A_total，