JP6073763B2 - Axial gap type permanent magnet synchronous motor - Google Patents

Description

  The present invention relates to a structure of an axial gap type permanent magnet synchronous motor having a gap in the axial direction.

  In recent years, the necessity of energy saving has been emphasized in industrial equipment, home appliances, automobile parts, and the like. Currently, most of the electricity produced in domestic power plants such as thermal power, hydropower, nuclear power, and wind power is produced by rotating electrical machines (generators) that are electromagnetic application products. Further, more than half of the amount of power used in the country is consumed by driving the rotating electrical machine.

  In these electromagnetic application products such as rotating electrical machines, a soft magnetic material is used for the iron core portion, and reducing the loss of the iron core portion is a means for realizing high efficiency of these products.

  Another measure to improve efficiency is to use a permanent magnet with a high magnetic force to increase the magnet torque per predetermined current so that the required torque can be obtained at a low current. There is a means for reducing (copper loss). As a method for improving the efficiency of the permanent magnet motor, a method of mounting a strong magnet such as a neodymium sintered magnet can be considered. However, since the materials used for such magnets contain rare metals that are mined only in limited production areas in the world, they have problems such as environmental problems and rising prices.

  Therefore, as an alternative method, there has been an increasing need to achieve high efficiency using ferrite magnets that have been produced in large quantities. JP 2010-115069 A (Patent Document 1) is cited as a method for improving motor efficiency when using a ferrite magnet. In Patent Literature 1, an axial gap type motor is used for the soft magnetic material of the iron core used in the permanent magnet motor, so that an amorphous structure with a low loss is used, and the volume of the permanent magnet is increased to reduce copper loss. A motor having a configuration in which two axial surfaces are rotors has been proposed.

JP 2010-115069 A

  Since the motor of Patent Document 1 is a permanent magnet synchronous motor, an inverter needs to be used for driving the motor. However, Patent Document 1 does not take into consideration the electric corrosion of a bearing by driving an inverter.

  Bearing electric corrosion is a corrosion phenomenon of a bearing and is generated by the following mechanism. That is, in a structure in which the outer ring of the bearing is in contact with the casing and the inner ring of the bearing is in contact with the motor rotation shaft, voltage variation of the rotation shaft occurs when an inverter is used. It occurs between the inner and outer rings. When the potential difference exceeds the dielectric strength of the bearing oil film, bearing current flows due to oil film breakdown. The bearing current causes electric corrosion (a phenomenon in which a metal corrodes due to dissolution of metal atoms that have lost their charge as ions flow when current flows between metals), and shortens the bearing life.

  Accordingly, it is necessary to reduce the voltage generated between the inner and outer rings of the bearing, the current during discharge, and the shaft voltage of the motor as a preceding stage.

  The motor shaft voltage is generated on the shaft in synchronization with the winding neutral point voltage (called common mode voltage) generated in the switching state of the inverter. This shaft voltage is generated because the paths from the winding to the rotor shaft are electrically coupled by electrical resistance or capacitance.

  In the axial gap motor having two rotors using the low-loss amorphous core of Patent Document 1 as the stator core, the stator core is divided into a plurality of parts, and the cross-sectional shape of the core is the same in the axial direction. The stator winding has a cross-sectional shape, and a stator winding having an inner peripheral surface similar to the outer peripheral surface of the stator core is disposed around the iron core. For this reason, at the axial end of the winding, the stator winding and the rotor magnet, or the rotor core portion are arranged to face each other with a gap therebetween, and the capacitance is increased. .

  The stator core has a structure in which a plurality of iron cores are independently held in the stator, and has a structure such as a housing that is difficult to be electrically coupled to a ground potential. For this reason, there exists a subject that the electrical coupling degree of a coil | winding and an axis | shaft falls and an axial voltage becomes high. If the shaft voltage increases, it will exceed the dielectric strength of the bearing oil film as described above, so it will be easy for the bearing to discharge, causing electric corrosion of the bearing, and shortening the period until failure. There is sex.

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present invention includes a plurality of means for solving the above-described problems. For example, two rotors that rotate about an axis and the two rotors are arranged so as to be sandwiched between the two rotors in the axial direction. A stator, a bearing, a case housing that fixes the stator with an insulating resin, an end bracket that holds the bearing and fully closes the stator and the rotor, and an axial end of the end bracket. With arranged fans,
A brush in contact with the axial end surface of the fan, the axial end surface of the fan is made of an alloy containing copper, the brush contains carbon, and the brush is added to the axial end surface of the fan. It has a pressurizing mechanism to press.

ADVANTAGE OF THE INVENTION According to this invention, the axial gap type permanent magnet synchronous motor which can reduce an axial voltage can be provided.

It is sectional drawing which shows the positional relationship of the brush arrange | positioned at the axial rear end part of the axial gap type permanent magnet synchronous motor in Example 1, and a brush holder. It is a perspective view which shows the structure of the brush of Example 1, a brush holder, and a screw. It is a perspective view which shows the structure of the motor part of the axial gap type permanent magnet synchronous motor of Example 1. FIG. It is a perspective view which shows the structure of the stator core of the axial gap type permanent magnet synchronous motor of Example 1. FIG. It is a perspective view which shows the positional relationship of the stator of the axial gap type permanent magnet synchronous motor of Example 1, a rotor, and a case housing. It is sectional drawing which shows the positional relationship of the stator of the axial gap type permanent magnet synchronous motor of a present Example, a rotor, and a housing. It is sectional drawing which shows the positional relationship of the stator of a conventional general radial gap motor, a rotor, and a housing. It is a figure which shows the basic conceptual diagram of an inverter. It is a figure explaining the common mode voltage in each switching state of an inverter. It is an equivalent circuit diagram showing each component of the motor as a simple model in which electrical capacitance and resistance are combined. It is a figure which shows the example which applied the axial gap type permanent magnet synchronous motor of Example 4 to the industrial use. It is sectional drawing which shows the positional relationship of the brush arrange | positioned at the axial rear end part of the axial gap type permanent magnet synchronous motor in Example 2, and a brush holder. It is sectional drawing which shows the positional relationship of the brush arrange | positioned at the axial rear end part of the axial gap type permanent magnet synchronous motor in Example 3, and a brush holder.

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

  FIG. 6 is a sectional view showing the configuration of an axial gap type permanent magnet synchronous motor. In FIG. 6, reference numeral 31 denotes a stator core, and 32 denotes a stator winding. A stator constituted by these is filled with an insulating resin and fixed to the case housing 40. Further, two rotors constituted by the rotor yoke 22 and the permanent magnet 24 are arranged in such a manner that the stator is sandwiched in the direction of the shaft (axis) 19 of the motor. The rotor is rotatably held by a bearing 13 that constitutes a bearing disposed on the end bracket 12 coupled to the case housing 40.

  FIG. 7 is a cross-sectional view of a conventional radial gap type permanent magnet synchronous motor.

  Permanent magnet synchronous motors are generally operated from the viewpoint of effective energy use while controlling the optimal torque and rotation speed according to demand in applications using motors such as pumps and blowers. . A basic conceptual diagram of the inverter is shown in FIG. For the motor portion, the winding is described as a star connection in order to easily indicate a neutral point. Since the delta connection and the star connection can be converted to each other, generality is not lost even if the star connection is assumed.

  The inverter device includes a converter unit that converts commercial power into direct current, a smoothing circuit that smoothes the pulsating voltage of the converter, and an inverter part that changes the average phase voltage per unit time arbitrarily (in a narrow sense) by switching operation at a high frequency. Consists of Assuming an ideal symmetrical three-phase balanced voltage, the voltage at the neutral point of the motor does not change with time and is constant. The AC voltage generated by the inverter device is given to each phase of the motor as a symmetrical three-phase balanced voltage. However, in an actual inverter device, the inverter part basically performs only ON / OFF operation, so The sex point voltage does not become a constant value but always fluctuates. This voltage is called a common mode voltage. The motor shaft voltage is generated due to this common mode voltage.

  FIG. 9 shows the common mode voltage in each switching state. In FIG. 9, the power semiconductor element is described as a switch for simplicity. Here, if the voltage across the smoothing circuit is E and the center of the smoothing circuit is the installation point, the common mode voltage in each switching state is E / 2, E / 6, -E / 6, -E / 2 as shown in the figure. obtain.

  There are two paths from the neutral point potential of the winding to the ground. One is winding → stator core → case housing, and the other is winding → stator core → rotor core → shaft → bearing → end bracket → case housing. These paths can be electrically expressed as a combination of capacitance and resistance. Since the resistance is very small, it is ignored and the simplest modeled equivalent circuit is shown in FIG. Here, Cwr is a capacitance between the winding and the rotor (rotor), Crf is a capacitance between the rotor and the case housing, and Cb is a capacitance between the inner and outer rings of the bearing. Although there are a plurality of bearings, they are described as a combined capacity for simplicity.

The ratio of the shaft voltage to the total voltage (Bearing Voltage Ratio, hereinafter abbreviated as BVR) can be expressed as the following equation (1).

BVR = Cwr / (Cwr + Crf + Cb) (1)

When the common mode voltage is set as Ecp, the peak voltage Vsp of the shaft voltage is expressed by the following equation (2).

Vsp = BVR x Ecp (2)

Since the common mode voltage Ecp is determined by the operation of the inverter as described above, the shaft voltage is generated in proportion to the BVR. For this reason, it can be seen that the BVR can be made smaller when the electrostatic capacity produced by each part of the motor and the electrostatic capacity of the bearing are smaller.

  If the two conductors are opposed to each other with an insulator between them, a capacitor is formed. The capacity of the capacitor is determined by geometrical factors such as the shape of the conductor forming the capacitor and the arrangement relationship between the two conductors. That is, it can be expressed by an equation that is proportional to the opposing area and inversely proportional to the distance.

  In the case of the axial gap type permanent magnet synchronous motor shown in FIG. 6, the facing area between the stator winding and the rotor and between the stator winding and the case housing is large, and the capacitance of Cwr may increase. Recognize. On the other hand, regarding the radial gap type permanent magnet synchronous motor shown in FIG. 7, the stator 30 is connected to the case housing 40 and is at zero potential (ground), and it can be seen that Cwr is reduced. For this reason, the axial type BVR is several times to several tens of times larger than the radial type. Therefore, the shaft voltage is higher than that of a normal inverter-driven radial motor, and a voltage of several tens of volts appears on the shaft. Therefore, when a high voltage appears, a discharge occurs in the bearing oil film, which causes electrolytic corrosion.

  Therefore, grounding with an earth brush is performed as a means for setting the potential generated on the shaft to the zero potential (grounding) side. In the normal radial type, even if the shaft voltage is high, only about a few volts is generated. Therefore, it is necessary to firmly contact the shaft and the brush to reduce the electrical resistance of the contact portion. Therefore, it is necessary to ensure a large contact area of the contact portion and to set a high pressure for pressing the brush, and there are problems such as a decrease in motor efficiency due to mechanical friction and a decrease in life due to brush wear. It is rarely used in products.

  In the axial gap type permanent magnet synchronous motor of the present embodiment, the shaft voltage is generated by several tens of volts. Therefore, even if the contact resistance is small, the current surely flows to the brush contact portion, so even if the contact area is small. It can also be configured with a carbon brush that has low friction and wear but high resistance. In addition, since the contact pressure can be lowered, the amount of wear can be kept small, and the present invention can be applied to an industrial motor without replacing the brush.

  FIG. 1 is a cross-sectional view showing the positional relationship between a brush and a brush holder arranged at the rear end portion of the axial gap type permanent magnet synchronous motor of this embodiment. FIG. 1A is an enlarged view, and FIG. 1B is an overall view. In FIG. 1, a hole for attaching the cylindrical brush holder 2 is arranged in the central portion of the fan cover 1 connected to the case housing 40 by attachment bolts. The hole is tapered so that the screw head of the countersunk screw 6 does not protrude, and the cylindrical brush holder 2 is fixed by tightening the countersunk screw 6. The central portion of the brush holder 2 is formed with a screw hole for fixing with a screw on the left side of the figure, and the right side has a groove shape adapted to the outer shape of the brush for arranging the brush 3. Thus, a groove for holding the brush slidably in the axial direction is formed. A compression spring 7 is disposed between the tip of the countersunk screw and the rear end of the brush, and has a pressurizing mechanism that pressurizes the brush toward the axial motor (to the right in the drawing). This brush is made of a material compression-molded with carbon as a main material.

  In FIG. 2, the perspective view of the structure of a brush and a brush holder part is shown. FIG. 2A shows the structure of the brush 3. The brush 3 has a substantially rectangular cross section, and a groove called a serration portion 15 is formed at the tip thereof. This is a shape for reducing the initial contact area in order to improve the initial contact between the brush and the sliding surface. Further, a connecting wire 4 (hereinafter referred to as pigtail) of a stranded wire conductor is fixed to one surface of the brush 3 by welding. In addition, a round crimp terminal 5 is connected to the tip of the pigtail. The round crimp terminal 5 is arranged between the fan cover 1 and the brush holder 2 by the countersunk screw 6 and is fastened and fixed with a screw.

  FIG. 2B is a perspective view showing the schematic structure of the brush holder 2 through the inside. In the present embodiment, a brush holding groove 18 having a substantially rectangular cross section for arranging the brush 3 in the central portion of the cylindrical brush holder 2 and a cylindrical portion for arranging the compression spring 7 on the opposite side thereof. And it has the screw hole 17 which is a thread part. In addition, a cutout groove 16 for passing the pigtail 4 is provided in a part of the circumferential direction of the cylinder. The brush 3 having a structure in which the fan cover 1 made of a conductor such as a metal and the round crimping terminal are screw-fixed by a flat head screw 6 in a state where the brush 3 with a pigtail is inserted and disposed in the brush holder 2 and the compression spring 7 is inserted. Is retained. The brush 3 itself is pressurized in a direction that protrudes in the motor shaft direction by the compression spring 7, but has a structure that is held by the pigtail 4 so as not to protrude.

  The brush holder 2 is fixed to the fan cover 1 with a flat head screw 6 so that the current fan cover can be used. However, the present invention is not limited to this. For example, the brush holder 2 and the fan cover 1 are integrated. Structure may be sufficient. The monolithic structure has the effect of simplifying assembly.

  In FIG. 1, a radial fan 10 is provided as a fan for cooling the motor housing at the shaft end portion of the motor with which the brush tip portion comes into contact. The radial fan 10 is fixed to a shaft portion having a structure that protrudes from the end bracket portion of the motor shaft 19 to the non-output side, and is rotatably held by a bearing 13 that constitutes a bearing disposed on the end bracket 12. . The radial fan 10 is fixed to the shaft by having a key groove in a part of the rotation direction of the shaft, and inserting the key 11 into the key groove portion so as not to slide in the rotation direction. A cylindrical collar 9 is provided in the axial direction, and the collar 9 is fixed to an axial shaft by tightening the collar 9 with a hexagonal head or a screw 8 having a chamfered head on two sides. ing.

  FIG. 2C shows the structure of the screw 8 which is an attachment portion for attaching the radial fan to the shaft. The axial end surface of the head portion of the screw 8 has a flat surface, and its surface roughness is a mirror surface state. The screw head is made of an alloy containing copper such as brass. The brush tip is pressed against the flat surface while being pressed by a compression spring, and the contact portion is configured to slide with low rotational friction. The shaft 19 of the motor is fixed in the rotational direction by arranging a rotor 20 and a key groove, and is fixedly arranged in the axial direction by a rotor holding nut 21. The rotor 20 in this embodiment has a structure having a back yoke 23 and a permanent magnet 24.

  With the above structure, even when shaft voltage is generated, current flows from the shaft through the fan fastening screw, brush, pigtail, metal fan cover, fan cover mounting bolt, case housing, and conductive member. Since it flows in the direction of the ground potential, it is possible to suppress the occurrence of bearing electrolytic corrosion that destroys the bearing oil film.

  FIG. 3 is a perspective view of the motor structure of the axial gap type permanent magnet synchronous motor of this embodiment. The axial gap type permanent magnet synchronous motor includes a single stator 30 disposed in the axial center portion and a rotor 20 disposed at both axial end portions thereof and having a magnet surface opposed to the stator by a circular surface. It has a structure.

  The rotor 20 is formed integrally with a rotor yoke 22 made of a magnetic material by using an annular permanent magnet 24 using a fixing method such as an adhesive. The permanent magnet 24 may be an annular integral ring magnet. However, if it is difficult to manufacture the permanent magnet 24 due to its size, a plurality of divided magnets may be combined to be used as an annular shape.

  In addition, the permanent magnet 24 is configured to be magnetized so that N poles and S poles are alternately arranged in the circumferential direction. In this embodiment shown in FIG. 3, the number of poles is 14. The shape per pole is a sector shape so as to have the same cross-sectional area at the same angle in the circumferential direction. In this embodiment, the fan-shaped opening angle is 360/14 degrees, which is about 25.7 degrees.

  In general, in a three-phase permanent magnet synchronous motor, the relationship between the number of rotor poles of the motor and the stator poles (slots) is generally 2: 3. One pole pair of the magnet motor is constituted by a pair of the N pole and S pole of the magnet. In the case of a three-phase motor, since the three-phase windings are arranged in this one pair of poles, there is a relationship between two magnet poles and three stator poles. In this embodiment, although the number of stator poles is 12 and 12 slots, the magnet poles are configured as 14 poles, and iron loss can be reduced by applying amorphous metal to the stator. It is. In addition, an increase in induced voltage constant (torque constant) is expected due to multipolarization. There are a plurality of other such combinations, and in the case of 12 slots, 10 poles can be adopted instead of 8 poles in a 2: 3 relationship. When the number of slots is 9, it is possible to adopt 8 poles and 10 poles instead of the originally 6 poles.

  In the rotor magnet of this embodiment, a ferrite sintered magnet is arranged on the surface. The reason for this is that when a surface magnet type in which all surfaces facing the stator are configured as magnets is formed, eddy currents are generated on the magnet surface due to magnetic flux from the stator windings, harmonics due to the slot arrangement of the stator core, etc. The reason for this is that the generation of the electromagnetism causes a problem that if the conductive metal magnet is employed, the efficiency is remarkably lowered. For this reason, rare earth bonded magnets, ferrite sintered magnets, ferrite bonded magnets, ferrite rubber magnets, and the like are suitable as the magnets that can be used for the rotor magnet of the axial gap type permanent magnet synchronous motor of this embodiment.

  Next, the structure of the stator will be described with reference to FIG. The stator shown in the axially central portion of FIG. 3 has a plurality of stator cores 31 having a sector cross section in the circumferential direction and arranged at equal intervals in the circumferential direction. A winding bobbin 33 made of an insulating member such as plastic or organic material is disposed around the stator core 31, and a conductor is wound around the winding bobbin in a shape similar to the outer periphery of the fan-shaped core. The shape is such that the stator winding 32 is disposed. In general, copper is used as the material of the conductor of the winding, but it is also possible to use a light wire with a specific gravity such as aluminum. The reason is that, in addition to the effects such as low price, the stator core, winding bobbin, and winding are arranged separately in the circumferential direction. This is because it is necessary to reduce the weight so that the weight of the iron core and the winding can be supported by the adhesive strength of the resin in order to adopt the structure of the mold motor that is fixed by impregnating the wire. Therefore, it is considered effective to use an aluminum conductor enamel magnet wire or the like in which an aluminum conductor is coated with an enamel coating such as polyester, amideimide or urethane.

  Since the stator winding 32 wound around the individual stator cores 31 has winding start and end winding lines, the number of stator cores 12 shown in FIG. 1 includes 24 terminal wires. Is pulled out. Although it may be processed as 24 lead lines as it is, it is desirable that the number is as small as possible in view of subsequent connection processing. In the present embodiment, an example in which two lead wires are formed from two adjacent windings by continuously winding two windings of the winding is illustrated. For this reason, there are 12 lines finally drawn. The drawn wire is usually connected to a motor terminal box by connecting a thin conductor with a vinyl-coated electric wire 36 constituted by a stranded wire. A ring sleeve 35 is used to connect the magnet wire of the motor winding and the vinyl-coated wire 36, and each wire is connected to the ring sleeve 35 by caulking, welding, or the like. After the connection, an insulating material is applied to a portion where the covering of the connection portion is exposed so that air, moisture and the conductor portion do not touch each other.

Next, the structure of the stator core and the manufacturing method thereof will be described with reference to FIG. The stator core is configured using an iron-based amorphous metal foil strip. This is because the loss of the iron-based amorphous metal is significantly lower than that of other magnetic materials and the magnetic permeability is high. High magnetic permeability means that a high magnetic flux density can be obtained compared to other magnetic materials even when using a magnet that can obtain only a relatively low magnetic field strength such as a ferrite magnet. In addition to the iron-based amorphous metal, a material such as permendur and iron-based nanocrystal metal is considered to have an application effect as a material having such a high magnetic permeability. Such a material is relatively thin and the metal itself has a high hardness, so that it is difficult to process and difficult to apply to a conventional motor or the like.
Therefore, the iron core can be made relatively easily as a structure as shown in FIG. In order to obtain an iron core having a fan-shaped cross section as shown in FIG. 3, the width of the iron-based amorphous metal foil strip having a constant width direction gradually increases from the lower part of FIG. 4 (a). In the final part, the cutting width is slightly narrowed to form the shape. Since the stacked amorphous foil strips are separated as they are, the stator core is inserted and held in the insulating winding bobbin 33 for winding the winding having the shape shown in FIG. Configure as.

Next, the relationship between the stator and rotor of the motor and the case housing will be described with reference to FIG. The case housing 40 basically has a cylindrical shape. The stator 30 and the rotor 20 are arranged inside the cylinder. The stator 30 is disposed at the axial center of the case housing 40 and is filled with an insulating resin so as to fill a space between the case housing 40 and the stator core 31, the stator winding 32, and the winding bobbin 33. It becomes a stator with an integrated case. Although the stator 30 is held by the adhesive strength of the resin, even if this resin causes a slight weight reduction due to aging or the like, the case housing 40 is prevented from being detached from the case. A step is provided on the inner side so that it does not come off in the axial direction of the stator, and a groove or protrusion such as a notch is provided in a part of the rotational direction so that it does not rotate in the rotational direction.
Since the heat generated from the winding is transmitted to the case housing 40 through the resin, and the heat is transmitted to cool the motor, it is desirable that the thickness of the resin is not so thick. It is also effective to add a fin structure to the case housing 40 for cooling to increase the heat radiation area and improve heat exchange with the outside air.

As described above, the axial gap type permanent magnet synchronous motor of the present embodiment can increase the motor efficiency by using a low-loss iron-based amorphous foil strip for the stator core. At present, industrial induction motors suffer from secondary copper loss due to secondary current, etc., so that the efficiency can be handled only up to IE3 level with the standard IE code determined by the International Electrotechnical Commission (IEC). In the axial gap type permanent magnet synchronous motor of the present embodiment, a motor can be designed in which no eddy current is generated in the magnet and both iron loss and copper loss are kept low. Therefore, motor efficiency higher than IE code IE4 can be realized. It becomes possible.
In the following, the configuration of the present embodiment will be rephrased collectively. The stator core of the axial gap type permanent magnet synchronous motor is made of iron-based amorphous metal, and the stator core is created using a simple manufacturing method that only cuts and laminates the iron-based amorphous metal foil strip, It has a stator core structure that is held by a member that holds the stator core.
The conductors that make up the stator winding have an inner peripheral shape that is similar to the outer peripheral shape of the stator core, and the stator core, the stator winding, and the inner periphery of the case housing are integrally bonded with resin. Structure. Since the structure is bonded with resin, the stator winding and the stator core have an insulating structure that is not electrically joined.
The rotor is arranged as a structure in which two axial surfaces of the stator are opposed to the magnet, and is configured to be rotatable through a bearing of a bearing holding end bracket coupled to the case housing. The structure of these motors is such that the case housing and the end bracket that holds the bearings at both ends in the axial direction are covered, and the stator and rotor are fully closed so that they are not exposed to the external atmosphere. And Thereby, the influence of the abrasion powder etc. by sliding of a brush can be avoided.

  Further, the output side of the rotor shaft has a structure in which a shaft having a predetermined shaft diameter corresponding to the torque projects as an output shaft as in a normal motor. Similarly, the non-output side is configured such that the shaft projects from the rotor shaft to the outside of the rear end bearing holding end bracket, and a fan for blowing air is attached to the projecting shaft. The fan shape adopts a radial fan shape in which air sucked from the rear side in the axial direction flows in the radial direction, and is configured to be covered with a fan cover provided to send the air flowing in the radial direction in the axial direction.

  The axial rear end portion of the screw, which is the mounting portion of the fan, is made of an alloy containing copper, and the axial end surface thereof is made as uneven as possible by mirror finishing. A brush holder that holds a brush made of a carbon-containing material is disposed at the center of the fan cover, and a brush that is movable in the axial direction by a spring and has a pressing force toward the shaft end of the motor. The tip is arranged so that the tip contacts the alloy part containing copper at the shaft end.

As described above, according to the present embodiment, in the axial gap motor, the facing area between the stator winding, the rotor magnet, and the rotor core is large, and the gap distance is small, so that the stator winding and the rotation are rotated. Even when the shaft voltage synchronized with the common mode voltage increases when the capacitance between the children increases, at the moment when the shaft voltage is generated, the brush goes to the ground potential via the fan cover and case housing. Since the shaft voltage can be set to the ground potential by supplying a current, the effect of preventing the occurrence of electrolytic corrosion of the bearing can be obtained even if the dielectric strength of the oil film portion in the bearing portion is low.
At this time, in the axial type motor, the shaft voltage is generated by several tens of volts, so even if the contact resistance is small, the current surely flows to the brush contact portion, so the contact area of the brush may be small, The contact pressure can also be lowered. Further, a carbon brush having a high resistance value but a small amount of wear can be used. For this reason, it is possible to construct a product that can achieve the life of an industrial motor without replacement.

  In addition, the brush holder placed in the center of the fan cover enables brush sliding at low peripheral speeds, reducing brush wear and maintaining a stable contact state by sliding copper and carbon. Since it can be maintained over a period of time, it is possible to realize a product life for industrial use and cost reduction.

  In addition, it is possible to reduce the loss of the motor core by adopting an iron-based amorphous material for the stator, so that the motor efficiency can be improved and the service life can be increased by the reduction of the loss.

  As described above, in this embodiment, it is possible to realize a shaft voltage reduction measure for the axial gap type permanent magnet synchronous motor, to realize high efficiency and high reliability (lifetime improvement), and at a low price without complicating the structure. Therefore, it is possible to provide a rotary electric machine with low cost and high efficiency.

  Example 2 will be described with reference to FIG. FIG. 12 is a diagram showing a positional relationship between the brush and the brush holder arranged at the rear end portion of the axial gap type permanent magnet synchronous motor of the present embodiment. 12A is an enlarged view of the shaft rear end portion of the motor, FIG. 12B is a view of the shaft rear end additional shaft 25, and FIG. 12C shows the relationship between the brush and the shaft rear end additional shaft 25. FIG. 12 (d) is a diagram showing the brush holder 27.

As shown in FIG. 12 (a), a shaft hole machining or a screw hole is arranged at the center of the front end portion of the rear end shaft of the axial gap type permanent magnet synchronous motor. The shaft rear end additional shaft 25 as shown in (b) is fixedly arranged by press-fitting or screw fastening. The shaft rear end additional shaft 25 is made of an alloy containing Cu, such as brass, and the shaft surface is a mirror-finished shaft having a surface roughness of 0.3 or more. As shown in FIG. 12C, the two brushes 26 are arranged so as to be opposed to each other by 180 degrees with respect to the circumferential surface of the shaft, and the brushes 26 are, for example, shown in FIG. Thus, the structure is held by the brush holder 27. The brush holder 27 has a portion that covers the outer peripheral surface of the brush, and has a structure in which the brush can be slidably held in the radial direction. A spring 61 is arranged so that a force that presses the slidable brush 26 toward the center of the brush holder is exerted, and the brush 26 presses against the shaft rear end shaft 25 by the spring. It becomes a structure arranged. The brush holder 27 is structured to be attached to the fan cover 1 using a screw hole 60 or the like.
In the structure shown in the first embodiment, since the sliding surface with the brush is the central portion of the shaft, the friction portion is small and wear is small. However, in the second embodiment, the shaft is somewhat narrowed or pressed to some extent. Even if the spring force for the above is weakened, it is considered that wear is more likely to occur than in the first embodiment. However, the brush holder 27 in the present embodiment is easy to attach to the fan cover, and can be easily replaced for each brush holder 27 only with screws. Further, the brush holder is made of a conductive metal material, so that it is possible to eliminate the trouble of connecting the pigtail connected from the brush as in the first embodiment to the ground potential component.

  Example 3 will be described with reference to FIG. In this embodiment, an example in which a brush wear powder countermeasure structure is applied is shown. FIG. 13A is an enlarged view of the rear end portion of the shaft of the motor, and FIG. 13B is a view showing the brush holder. In FIG. 13 (a), it is possible to arrange a ring-shaped sealing material 63 on the inner peripheral portion of the brush holder so that the wear powder is not discharged out of the brush holder. The sealing material 63 can also be applied to the first embodiment by changing the arrangement. Because this sealant has a structure in which the wear powder is held in the brush sliding surface gap inside the brush holder, either a sufficient gap is placed or the brush powder collected in the area surrounded by the seal material such as an O-ring It is set as the structure which provides the area | region (for example, the hole 64 etc.) for holding. As a result, it is possible to prevent problems such as the abrasion powder of the brush penetrating into the brush sliding surface, hindering the sliding and not contacting.

FIG. 11 shows an example in which the axial gap type permanent magnet synchronous motor of this embodiment is applied to an industrial application.
Motors for industrial use have a relatively large capacity and a large amount of power consumption, so the energy saving effect is also great. As described above, since the axial gap type permanent magnet synchronous motor of the present embodiment can realize IE4 or more of the IEC IE code, its power consumption reduction effect is great. In addition, since pumps, fans, and the like are desired to be thin, they can contribute to a reduction in installation area. FIG. 11A shows an industrial pump in which the thin pump 45 and the axial gap type permanent magnet synchronous motor 50 of this embodiment are mounted. FIG. 11B is a schematic diagram when the axial gap type permanent magnet synchronous motor 50 and the thin fan 46 of the present embodiment are configured. Moreover, there is an elevator hoisting machine as an application where a thin shape is desired. FIG. 11C shows an example of a hoisting machine. Since the hoisting machine 47 made of a sheave for winding the rope and the axial gap type permanent magnet synchronous motor 50 need to be thinly formed, the axial gap type permanent magnet synchronous motor of this embodiment is suitable.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Fan cover, 2 ... Brush holder, 3 ... Brush, 4 ... Pigtail, 5 ... Round crimp terminal, 6 ... Flat head screw, 7 ... Compression spring, 8 ... Screw, 9 ... Fan holding collar, 10 ... Radial fan, DESCRIPTION OF SYMBOLS 11 ... Key, 12 ... End bracket, 13 ... Bearing, 15 ... Serration groove, 16 ... Notch groove, 17 ... Screw hole, 18 ... Brush holding groove, 19 ... Shaft (axis), 20 ... Rotor, 21 ... Rotation Retainer retaining nut, 22 ... Rotor yoke, 23 ... Back yoke, 24 ... Permanent magnet 30 ... Stator, 31 ... Stator iron core, 32 ... Stator winding, 33 ... Winding bobbin, 34 ... Connection crossover wire, 35 ... Ring sleeve, 36 ... Vinyl-coated electric wire, 40 ... Case housing, 45 ... Pump, 46 ... Fan, 47 ... Hoisting machine, 50 ... Axial gap type permanent magnet synchronous motor .

Claims (5)

Two rotors that rotate about an axis;
A stator disposed so as to be sandwiched between the two rotors in the direction of the shaft;
A bearing,
A case housing for fixing the stator with insulating resin;
An end bracket that holds the bearing and fully closes the stator and the rotor;
A fan disposed at an axial end of the end bracket;
A brush in contact with the axial end surface of the fan,
An axial end face of the fan is made of an alloy containing copper,
The brush includes carbon;
Further have a pressing mechanism for pressing the brush in the axial direction end surface of said fan,
The axial gap type permanent magnet synchronous motor , wherein the brush holder for holding the brush is provided with a groove for slidably holding a pigtail which is a connection line connected to the brush . Two rotors that rotate about an axis;
A stator disposed so as to be sandwiched between the two rotors in the direction of the shaft;
A bearing,
A case housing for fixing the stator with insulating resin;
An end bracket that holds the bearing and fully closes the stator and the rotor;
A fan disposed at an axial end of the end bracket;
A brush in contact with the axial end surface of the fan,
An axial end face of the fan is made of an alloy containing copper,
The brush includes carbon;
Furthermore, it has a pressurizing mechanism that pressurizes the brush on the axial end surface of the fan,
The brush holder for holding the brush is structured to be held by a screw on a fan cover attached for the purpose of protecting the fan, and the brush and the fan cover via a pigtail that is a connection line connected to the brush. Are connected so as to be in an electrically conductive state , an axial gap type permanent magnet synchronous motor. Two rotors that rotate about an axis;
A stator disposed so as to be sandwiched between the two rotors in the direction of the shaft;
A bearing,
A case housing for fixing the stator with insulating resin;
An end bracket that holds the bearing and fully closes the stator and the rotor;
A fan disposed at an axial end of the end bracket;
A brush in contact with the axial end surface of the fan,
An axial end face of the fan is made of an alloy containing copper,
The brush includes carbon;
Furthermore, it has a pressurizing mechanism that pressurizes the brush on the axial end surface of the fan,
The brush holder for holding the brush has a structure formed integrally with a fan cover attached for the purpose of protecting the fan, and the brush and fan cover are connected via a pigtail which is a connection line connected to the brush. Are connected so as to be in an electrically conductive state , an axial gap type permanent magnet synchronous motor. Two rotors that rotate about an axis;
A stator disposed so as to be sandwiched between the two rotors in the direction of the shaft;
A bearing,
A case housing for fixing the stator with insulating resin;
An end bracket that holds the bearing and fully closes the stator and the rotor;
A fan disposed at an axial end of the end bracket;
A brush in contact with the axial end surface of the fan,
An axial end face of the fan is made of an alloy containing copper,
The brush includes carbon;
Furthermore, it has a pressurizing mechanism that pressurizes the brush on the axial end surface of the fan,
The brush holder for holding the brush is structured to be held by a screw on a fan cover attached for the purpose of protecting the fan, and is made of a conductive metal material. The brush and the fan cover are electrically connected. An axial gap type permanent magnet synchronous motor characterized by being connected so as to be electrically conductive . Two rotors that rotate about an axis;
A stator disposed so as to be sandwiched between the two rotors in the direction of the shaft;
A bearing,
A case housing for fixing the stator with insulating resin;
An end bracket that holds the bearing and fully closes the stator and the rotor;
A fan disposed at an axial end of the end bracket;
A brush in contact with the axial end surface of the fan,
An axial end face of the fan is made of an alloy containing copper,
The brush includes carbon;
Furthermore, it has a pressurizing mechanism that pressurizes the brush on the axial end surface of the fan,
The brush holder for holding the brush has a structure formed integrally with a fan cover attached for the purpose of protecting the fan , and is made of a conductive metal material. The brush and the fan cover are electrically connected. An axial gap type permanent magnet synchronous motor characterized by being connected so as to be electrically conductive.

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