JP4600712B2 - Linear motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear motor that requires high-speed, high acceleration / deceleration linear motion in the FA field such as machine tools and semiconductor manufacturing apparatuses.
[0002]
[Prior art]
Conventionally, linear motors that require high-speed, high acceleration / deceleration linear motion in the FA field such as machine tools and semiconductor manufacturing apparatuses are desired to have a large maximum thrust with respect to the motor size. For example, such a linear motor is disclosed in Japanese Patent Publication No. 5-34901. 8A and 8B show a conventional linear motor, in which FIG. 8A shows a side sectional view thereof, and FIG. 8B shows an enlarged view of a magnetic pole in FIG. In the figure, the direction of the arrow (↑ ↓) indicates the magnetization direction of each permanent magnet.
In the figure, 1 is a stator, 2 is an inductor, 3 is an inductor tooth, 10 is a mover, 11 is an armature, 12 is an armature core, 13 is a tooth, 14 is a yoke, and 15 is an armature winding. , 16 are magnetic poles, and 18 is a permanent magnet.
The stator 1 is constituted by an inductor 2 made of a magnetic material having inductor teeth 3 formed at a predetermined interval λ in the traveling direction. For example, laminated magnetic steel plates are used as the magnetic material.
The armature 10 includes an armature core 12 in which three teeth 13 and a yoke 14 connecting them are integrated, and a three-phase (U, V, W) armature winding 15 wound around the three teeth 13. The armature 11 is composed of a magnetic pole 16 provided at the tip of each tooth 13. For example, laminated electromagnetic steel sheets are used as the material for the armature core 12. Six permanent magnets 18 are arranged so that adjacent magnetic poles 16 having six poles have different polarities so that the pitch Pm is λ / 2. That is, the angle difference θ between the magnetization directions of the adjacent permanent magnets 18 is 180 degrees, and the number n of permanent magnets used for the magnetic pole per pole is 1. The spacing between adjacent teeth 13 is 4 × λ + λ / 3, which is the sum of the width 3 × λ of the teeth 13 and the width λ + λ / 3 between the teeth 13. The mover 10 is supported by a linear guide or the like (not shown) so as to be movable in the traveling direction.
Next, the operation principle will be described.
The magnetic flux of the permanent magnet 18 flows through a magnetic circuit constituted by the teeth 13, the yoke 14, the air gap, and the inductor teeth 3. Since the phase difference of the teeth 13 of each phase is 120 degrees in electrical angle, when the mover 10 is moved, magnetic fluxes having a difference of 120 degrees in electrical angle are linked to the armature windings 15 in the respective phases. A three-phase induced voltage is generated. Conversely, when a three-phase sinusoidal current is applied to the armature winding 15 of each phase, a thrust is generated as a three-phase synchronous motor, and the mover 10 moves linearly on the stator 1.
[0003]
[Problems to be solved by the invention]
In the conventional linear motor, in the relationship between the current applied to the armature winding 15 and the thrust, when the current increases, the thrust is not generated as the current increases, and a predetermined maximum thrust cannot be obtained. As shown, there is a non-linear region where the thrust is saturated. This saturation phenomenon of the thrust is a magnetic flux in which the magnetic flux of the permanent magnet 18 is superimposed on the magnetic flux generated by the armature winding 15 (meaning a magnetic flux proportional to the generated thrust, hereinafter referred to as “main magnetic flux”). Happens to saturate at. If the current is small, the thrust is linear, but if a current corresponding to the main magnetic flux exceeding the saturation magnetic flux density of the inductor teeth 3 flows, the thrust becomes nonlinear. Further, when the current is increased, the magnetic flux passing through the inductor teeth 3 is completely saturated, and the thrust is not changed at all no matter how much the current is increased. For this reason, in the case of a linear motor of the prior art, there is a problem that the required acceleration / deceleration performance cannot be obtained due to the above-mentioned phenomenon of thrust saturation, and sufficient maximum thrust cannot be obtained for the motor size. It was.
Therefore, in order to improve the linearity of the thrust of the linear motor, either the magnetic saturation of the inductor teeth 3 is suppressed, or a magnetic pole structure that increases the magnetic flux density of the gap between the armature 11 and the inductor 2 is adopted. This measure is necessary. In the former, the tooth width of the inductor teeth 3 for improving the linearity of thrust has been studied, and it is already a known technique. The latter is made possible by recent rare-earth high-performance permanent magnets, but no dramatic improvement has been observed, and another improvement measure is necessary.
The present invention has been made to solve the above problems, and has a magnetic pole structure capable of increasing the magnetic flux density of the air gap between the armature and the inductor and greatly improving the maximum thrust as compared with the conventional one. An object is to provide a linear motor.
[0004]
[Means for Solving the Problems]
In order to solve the above problem, the present invention of claim 1 is directed to an armature winding wound around a tooth of an armature core formed by laminating electromagnetic steel sheets and a plurality of magnetic poles (one pole) arranged at the tip of the tooth. An armature having a contact length with a magnetic pole pitch Pm), and an inductor having an inductor tooth made of a magnetic material and disposed opposite to the magnetic pole via a gap, the armature and the inductor In a linear motor that performs relative movement using either one of these as a mover and the other as a stator , when the two permanent magnets are arranged in the magnetic pole per pole, the magnetization direction η1 of one permanent magnet is The moving direction of the mover is shifted by an angle of 0 ° <η1 <90 °, and the magnetization direction η2 of the other permanent magnet is shifted by an angle of η2 = 180 ° −η1 with respect to the moving direction of the mover. , Magnetic pole pitch of the two permanent magnets The width in the direction is equal .
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a linear motor showing a first embodiment of the present invention, in which (a) is a side sectional view thereof and (b) is an enlarged view of a magnetic pole in (a). In the drawing, the direction of the arrow (↑ ↓, etc.) indicates the magnetization direction of each permanent magnet. In addition, components having the same constituent elements as those of the prior art are denoted by the same reference numerals, description thereof is omitted, and only different points will be described.
In the figure, 17a indicates a permanent magnet having a width in the magnetic pole pitch direction as Wa, and 17b indicates a permanent magnet having a width in the magnetic pole pitch direction as Wb.
The fundamental differences of the present invention from the prior art are as follows.
N permanent magnets (n is an integer of 2 or more) are arranged adjacent to each other so that the magnetization directions of the magnetic poles per pole are alternately different, and the angle difference θ between the magnetization directions of adjacent permanent magnets is set to θ. = 180 ° / n.
FIG. 1 shows a case where the magnetic pole per pole is composed of n = 2 permanent magnets 17a and 17b, and the angle difference θ in the magnetization direction is set to 90 degrees. Specifically, the magnetization direction of one permanent magnet 17a coincides with the moving direction of the mover, and the magnetization direction of the other permanent magnet 17b is shifted by an angle of 90 ° with respect to the magnetization direction of the permanent magnet 17a. The relationship between the pitch Pm and the width Wb of the permanent magnet 17b is 0.3 ≦ Wb / Pm <1.0.
Since the operation of the linear motor is basically the same as that of the prior art, the description is omitted.
[0006]
Next, confirmation of the effect of the thrust characteristic according to the embodiment of the present invention will be described below with reference to FIGS.
FIG. 2 is a diagram showing the relationship between the current applied to the linear motor armature winding of the present invention and the prior art and the thrust. 3A and 3B are explanatory views showing the flow of the main magnetic flux between the magnetic pole and the inductor teeth according to the embodiment of the present invention. FIG. 3A shows the first embodiment, and FIG. 3B shows the case of the prior art.
The main magnetic flux in the prior art flows into the side surface and the tip of the inductor tooth 3 as shown in FIG. The main magnetic flux flowing into the tip of the inductor teeth 3 has a sparse distribution of the main magnetic flux flowing in the moving direction of the mover from the magnetic pole structure. That is, the thrust is small.
On the other hand, in the first embodiment, as shown in FIG. 3A, the distribution of the main magnetic flux flowing into the side surface and the tip of the inductor tooth 3 by the permanent magnet 17a whose magnetization direction is the traveling direction of the mover. Is dense. In other words, it means obtaining a larger thrust than the prior art. Therefore, the first embodiment of the present invention employs the magnetic pole structure described above, so that the magnetic flux density of the air gap by the permanent magnets 17a and 17b can be increased in thrust and current at each current value as compared with the prior art as shown in FIG. Maximum thrust can be greatly improved.
[0007]
Next, confirmation of the effect in the relationship between the width of the permanent magnet and the maximum thrust will be described.
FIG. 4 is a graph showing the relationship between the ratio of Wb of the permanent magnet 17b to the magnetic pole pitch Pm (Wb / Pm) and the maximum thrust ratio of the present invention with respect to the prior art.
In the figure, it can be confirmed that Wb / Pm <0.3 is lower than that of the prior art and that a maximum thrust larger than that of the prior art is obtained in the range of 0.3 ≦ Wb / Pm <1.0. In particular, the maximum thrust is improved by 10% around Wb / Pm = 0.6.
[0008]
Next, a second embodiment will be described. FIG. 5 is an enlarged view of the magnetic pole in the second embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment. In addition, the direction of the arrow in the figure indicates the magnetization direction of each permanent magnet, as in the first embodiment. The second embodiment is different from the first embodiment in that when two permanent magnets 17c and 17d are arranged in the magnetic pole per pole, the magnetization direction η1 of one permanent magnet 17c is set to be the same as that of the mover. The permanent magnet 17c is shifted by an angle of 0 ° <η1 <90 ° with respect to the traveling direction, and the magnetization direction η2 of the other permanent magnet 17d is shifted by an angle of η2 = 180 ° −η1 with respect to the traveling direction of the mover. , 17d have the same width Wc, Wd in the magnetic pole pitch direction. In the second embodiment, the magnetic flux density in the gap between the armature and the inductor is increased as in the first embodiment, so that the maximum thrust can be improved as compared with the prior art. Further, the permanent magnet used in the first embodiment is one permanent magnet 17a having the same magnetization direction as the moving direction of the mover, and the other permanent magnet 17b having a magnetization direction shifted by 90 ° from the permanent magnet 17a. In contrast to the need for a type, the second embodiment can be constructed with a single type of permanent magnet whose magnetization direction is symmetric with respect to the moving direction of the mover, so the number of parts can be reduced and the magnetic poles can be assembled. Can be easily. The operation of the linear motor is the same as that of the conventional example, and the reason for the improvement in thrust is basically the same as that of the first embodiment, so that the description thereof is omitted.
[0009]
Next, a third embodiment will be described.
FIG. 6 is an enlarged view of the magnetic pole in the third embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment. The direction of the arrow in the figure indicates the magnetization direction of each permanent magnet, as in the first and second embodiments.
The third embodiment is different from the first and second embodiments in that four permanent magnets 17e, 17f, 17g, and 17h, each having a different magnetic direction, are arranged adjacent to each other. Is a point. In the third embodiment, as in the first and second embodiments, the magnetic flux density in the gap between the armature and the inductor is increased, so that the maximum thrust can be improved as compared with the prior art.
Further, the third embodiment has a magnetic pole structure without an irreversible demagnetizing action due to a reverse magnetic field that easily occurs between the permanent magnets 17a and 17b having the orthogonal magnetization directions in the first embodiment. In the first embodiment, since the magnetization directions of the adjacent permanent magnets 17a and 17b are 90 degrees, the permanent magnet 17a serves as a reverse magnetic field magnetomotive force source, and partially applies a reverse magnetic field to the permanent magnet 17b. Therefore, in the third embodiment, a permanent magnet 17f having a 45 ° inclination direction as a magnetization direction is inserted between the permanent magnets 17e and 17g. As a result, the magnetization direction of the adjacent permanent magnets changes smoothly, and a magnetic pole structure having no irreversible demagnetizing action can be configured.
The operation of the linear motor is the same as that of the conventional example, and the reason for the improvement in thrust is basically the same as that of the first embodiment, so that the description thereof is omitted.
[0010]
Next, a fourth embodiment will be described.
FIG. 7 is an enlarged view of the magnetic pole in the fourth embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment. In addition, the direction of the arrow in a figure has shown the magnetization direction of each permanent magnet like the 1st-3rd Example.
The fourth embodiment is different from the first to third embodiments in that the permanent magnets arranged in the plurality of magnetic poles are arranged so that the magnetization direction becomes an arc shape toward the moving direction of the mover. This is a point magnetized by a single permanent magnet 17i magnetized with 6 poles.
As in the first to third embodiments, the fourth embodiment can improve the maximum thrust with respect to the prior art.
In the fourth embodiment, since the plurality of magnetic poles are constituted by one permanent magnet, the number of parts can be greatly reduced, the magnetic poles can be easily assembled, and the magnetic strength of the magnetic poles can be increased. Yes.
The operation of the linear motor is the same as that of the conventional example, and the reason for improving the thrust is basically the same as that of the first embodiment, and will not be described.
[0011]
In the above embodiment, the armature is arranged on the mover. However, even if the structure is arranged on the stator and the inductor is arranged on the mover, the effect of the present invention can be exhibited similarly. Needless to say.
Moreover, although the armature comprised by three teeth was shown, the same effect can be acquired even if it has connected a plurality of them, or has a plurality of teeth in one armature.
[0012]
【The invention's effect】
With the above configuration, the following effects can be obtained.
(1) According to the first embodiment, the angle difference θ between the magnetization directions of n adjacent permanent magnets arranged in the magnetic pole per pole is shifted by θ = 180 ° / n. . Also, when two permanent magnets are arranged in one magnetic pole per pole, the magnetization direction of one permanent magnet having a width in the magnetic pole pitch direction as Wa matches the traveling direction of the mover, and the width in the magnetic pole pitch direction The magnetization direction of the other permanent magnet with Wb being shifted from the magnetization direction of one permanent magnet by an angle of 90 °, and the relationship between the magnetic pole pitch Pm and the width Wb of the other permanent magnet is 0.3. ≦ Wb / Pm <1.0 is adopted, so that the main magnetic flux flowing into the side surface and the tip of the inductor teeth is increased by the permanent magnet whose magnetization direction is reversed by 90 ° with respect to the moving direction of the mover. Therefore, the magnetic flux density of the air gap between the armature and the inductor can be increased, and the thrust and maximum thrust at each current value can be improved as compared with the prior art. In particular, when the width Wb of the other permanent magnet is 0.6 times the magnetic pole pitch, the maximum thrust can be improved by 10% compared to the prior art.
(2) According to the second embodiment, when two permanent magnets are arranged in one magnetic pole, the magnetization direction η1 of one permanent magnet is 0 ° <with respect to the moving direction of the mover. The angle of η1 <90 ° is shifted, and the magnetization direction η2 of the other permanent magnet is shifted by an angle of η2 = 180 ° −η1 with respect to the moving direction of the mover, and the width in the magnetic pole pitch direction of the two permanent magnets Since Wc and Wd are made equal, the magnetic flux density in the gap between the armature and the inductor is increased as in the first embodiment, so that the maximum thrust can be improved as compared with the prior art. Furthermore, since all can be comprised with the same permanent magnet, a number of parts can be decreased and the assembly of a magnetic pole can be made easy.
(3) According to the third embodiment, since the magnetic poles per pole are arranged adjacent to each other using four permanent magnets having different magnetization directions, as in the first and second embodiments, Since the magnetic flux density of the air gap between the armature and the inductor is increased, the maximum thrust can be improved as compared with the prior art. Furthermore, there is an effect of preventing an irreversible demagnetizing action that occurs between permanent magnets whose magnetization direction is perpendicular to the traveling direction.
(4) According to the fourth embodiment, the permanent magnets arranged in the plurality of magnetic poles have a configuration in which multipole magnetization is performed so that the magnetization direction becomes an arc shape toward the moving direction of the mover. Therefore, as in the first to third embodiments, the maximum thrust can be improved with respect to the prior art. Furthermore, since the plurality of magnetic poles are constituted by a single permanent magnet, the number of parts can be greatly reduced, the assembly of the magnetic poles can be facilitated, and the mechanical strength of the magnetic poles can be increased.
[Brief description of the drawings]
FIG. 1 is a linear motor showing a first embodiment of the present invention, in which (a) is a side sectional view thereof, and (b) is an enlarged view of a magnetic pole in (a).
FIG. 2 is a diagram showing the relationship between the current applied to the linear motor armature winding of the present invention and the prior art and the thrust.
FIGS. 3A and 3B are explanatory views showing the flow of main magnetic flux between a magnetic pole and an inductor tooth according to an embodiment of the present invention, in which FIG. 3A shows this embodiment, and FIG.
FIG. 4 is a graph showing the relationship between the ratio of Wb of the permanent magnet 17b to the magnetic pole pitch Pm (Wb / Pm) and the maximum thrust ratio of the present invention relative to the prior art in the first embodiment of the present invention. .
FIG. 5 is an enlarged view of a magnetic pole in the second embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
FIG. 6 is an enlarged view of the magnetic pole in the third embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
FIG. 7 is an enlarged view of a magnetic pole in the fourth embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
8A and 8B are prior art linear motors, in which FIG. 8A is a side sectional view thereof, and FIG. 8B is an enlarged view of a magnetic pole in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stator 2 Inductor 3 Inductor tooth 10 Mover 11 Armature 12 Armature core 13 Teeth 14 yoke 15 Armature winding 16 Magnetic poles 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i Permanent magnet

Claims (1)

An armature having an armature winding wound around a tooth of an armature core formed by laminating electromagnetic steel sheets and a plurality of magnetic poles (the length per pole is a magnetic pole pitch Pm) disposed at the tip of the tooth; ,
An inductor having an inductor tooth made of a magnetic material and opposed to the magnetic pole through a gap ;
In a linear motor that performs relative movement using either one of the armature or the inductor as a mover and the other as a stator,
When two permanent magnets are arranged in the magnetic pole per one pole, the magnetization direction η1 of one permanent magnet is shifted by an angle of 0 ° <η1 <90 ° with respect to the moving direction of the mover, The magnetization direction η2 of the other permanent magnet is shifted by an angle of η2 = 180 ° −η1 with respect to the moving direction of the mover,
A linear motor characterized in that the two permanent magnets have the same width in the magnetic pole pitch direction .

Images