JP2015073350A - Rotor and electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor and an electric motor that ensure the fixing of a permanent magnet to a back yoke, are processed easily, and can be manufactured at low costs.SOLUTION: A permanent magnet holding member 33 is integrally molded by molding synthetic resin on the peripheral part of the rotor cylindrical part of a back yoke 10. Connection parts 35 are formed in 8 areas equally dividing an annular part 34 in a circumferential direction on the front side in a rotating direction, have a portion obliquely extending radially outward from the annular part 34, and have a permanent magnet holding member claw parts 36 jutting out in a circumferential direction at the leading end part of this portion opposite to the rotating direction. The back yoke 10 has, on the rear side in the rotating direction, a portion obliquely extending radially outward from the annular part 34 and forming an approximately V-shaped cross section between the corresponding connection parts 35. The leading end part of this portion in the rotating direction has integrally-formed back yoke claw parts 37 jutting out in a circumferential direction. A permanent magnet 8 is inserted between the permanent magnet holder member claw parts 36 of the corresponding adjacent connection parts 35 from the axial direction and thus held.

Description

  The present invention relates to a rotor and an electric motor in, for example, an electric oil pump device used as a hydraulic pump for supplying hydraulic pressure to a transmission of an automobile.

  2. Description of the Related Art Conventionally, in an automobile that performs an idling stop that stops an engine when the vehicle is stopped, an electric oil pump device has been used to ensure the supply of hydraulic pressure to the transmission even during an idle stop. In the electric oil pump device, an oil pump, an electric motor for driving the pump, and a controller for controlling the rotation of the electric motor are incorporated in a common housing and mounted on the vehicle body.

  As an electric motor in this type of electric oil pump device, a DC brushless motor using a permanent magnet as a rotor is used. In a conventional DC brushless motor, a ring-shaped or segment-shaped permanent magnet is fixed to the outer peripheral surface of a cylindrical rotor body (back yoke). As such an electric motor, a synthetic resin permanent magnet holding member fixedly provided on the outer peripheral portion of the rotor body is provided with a rotor in which a plurality of permanent magnets are held (for example, , See Patent Document 1).

JP 2010-207075 A

  The electric motor as described above has a rotor structure in which a synthetic resin permanent magnet holding member is integrally formed on a rotor body by a mold, and a segment magnet is attached and held by a magnetic force without using an adhesive. Positioning of the segment magnets on the rotor body and prevention of peeling of the permanent magnets are performed by the permanent magnet holding claws formed in the axial direction of the permanent magnet holding member and the magnetic force of the permanent magnets themselves.

  However, when the rotational speed of the electric motor increases, the magnetic force decreases due to an increase in centrifugal force due to the high-speed rotation of the rotor and a change in the air gap between the rotor and the stator. As a result, a force exceeding the attracting force of the permanent magnet is applied to the permanent magnet in the radial direction with respect to the rotating shaft, and the function of holding the permanent magnet may not be satisfied. For this reason, in particular, there is a possibility that the claw portion of the permanent magnet holding member made of synthetic resin is deformed by the force applied to the permanent magnet on the rear side with respect to the rotation direction, and the permanent magnet is peeled off from the rotor body and falls off.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotor and an electric motor that can be manufactured at low cost because the permanent magnet can be securely fixed to the rotor body, the rotor body can be easily processed. Is to provide.

  In order to solve the above-mentioned problems, the invention described in claim 1 includes a cylindrical rotor main body, a synthetic resin permanent magnet holding member fixedly provided on an outer peripheral portion of the rotor main body, and the rotor main body. A plurality of permanent magnets that are in contact with the outer peripheral surface of the rotor main body, and the permanent magnet holding member is in contact with the outer peripheral portions of both end surfaces of the rotor body, and The rotor main body includes a connecting portion that connects the two annular portions on the outer peripheral surface of the rotor main body and holds the permanent magnet, and extends in a circumferential direction at a portion extending radially outward from the annular portion of the connecting portion. A plurality of first permanent magnet holding claws that are integrally formed so as to protrude to the front side in the rotational direction of the rotor, and the rotor body extends circumferentially in a portion extending radially outward of the rotor body on the outer peripheral surface. Tension on the rear side in the rotation direction A plurality of second permanent magnet holding claws formed integrally with each other, and the permanent magnets have the first permanent magnet holding claws and the second permanent magnet holding adjacent to each other in the circumferential direction. The gist is to be held between the claw portions.

  The gist of the invention of claim 2 is that, in the rotor of claim 1, the second permanent magnet holding claw portion is formed over the entire length in the axial direction.

  A third aspect of the present invention is the rotor according to the first aspect, wherein the second permanent magnet holding claw portion is formed to have a predetermined length from both ends in the axial direction. And

  The gist of the invention according to claim 4 is that the electric motor includes the rotor according to any one of claims 1 to 3.

  According to the first aspect of the present invention, the rotor on the front side in the rotational direction of the rotor formed integrally with the permanent magnet holding member made of synthetic resin integrally molded by molding on the outer peripheral portion of the rotor body adjacent to the circumferential direction. No permanent magnet is used between the first permanent magnet holding claw and the second permanent magnet holding claw on the rear side in the rotational direction of the rotor formed integrally with the metal rotor body. Attach and hold with. As a result, even if a force is applied to the rear side of the rotation direction of the permanent magnet due to the rotation of the rotor, the permanent magnet can be securely fixed to the rotor body without peeling off from the rotor body in the radial direction and falling off. .

  According to the invention of claim 2, since the second permanent magnet holding claw portion formed integrally with the rotor body is provided over the entire length in the axial direction, the rotor body is formed by a laminated structure such as an electromagnetic steel plate. In this case, the mold and the molding process can be simplified, the rotor body can be easily processed, and can be manufactured at low cost.

  According to the invention of claim 3, since the second permanent magnet holding claw portion is divided and arranged at both ends in the axial direction, the rotor main body is reduced in weight, and the second permanent magnet holding claw portion is used. The permanent magnet can be securely held.

  According to the invention of claim 4, the electric motor including the rotor can securely fix the permanent magnet with a structure that does not use an adhesive to the rotor body, and the rotor body can be easily processed. It can be manufactured at low cost.

1 is a longitudinal sectional view showing a schematic configuration of an electric oil pump device according to a first embodiment of the present invention. The top view of the rotor of the electric motor seen from the AA direction in FIG. The perspective view which shows the rotor main body and permanent magnet holding member of the rotor of the electric motor in FIG. The longitudinal cross-sectional view of the rotor of the electric motor which concerns on the 2nd Embodiment of this invention.

Hereinafter, a rotor of an electric motor applied to an electric oil pump device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a schematic configuration of an electric oil pump device 1 according to a first embodiment of the present invention. In the following description, the left side of the drawing is the front and the right side is the rear.

  As shown in FIG. 1, an electric oil pump device 1 includes an oil pump 2 and an electric motor 3 that rotationally drives the oil pump 2 integrated in a housing body. A controller (ECU) 4 that controls the rotation of the electric motor 3 is also incorporated in the housing. In this embodiment, the oil pump 2 uses a trochoid type internal gear pump, and the electric motor 3 uses a DC brushless sensorless motor having a three-phase winding.

  The housing body of the electric oil pump 1 is formed of a pump plate 14 and a pump housing 15 formed of a metal nonmagnetic material (for example, aluminum die casting), and a thermoplastic resin material (for example, PPS, PBT resin). The motor housing 17 and the cover 20 are formed. The pump housing 15, the motor housing 17 and the cover 20 constitute a waterproof housing. The electric oil pump device 1 is fastened to a transmission or an engine case (not shown) via a flange projecting from the end face of the pump plate 14 with bolts arranged in the circumferential direction with respect to the rotation axis center through a plurality of mounting holes. It is fixed.

  The pump housing 15 is a thick plate-like case that extends in a radial direction orthogonal to the axial direction, and a pump chamber 13 that is open at the front and rear is formed at the center thereof. A pump plate 14 is fixed to the front surface of the pump housing 15 via an O-ring 16, and the front surface of the pump chamber 13 is closed. An outer rotor 11 constituting a pump rotor of the oil pump 2 is rotatably accommodated in the pump chamber 13, and an inner rotor 12 having external teeth meshing with the outer rotor 11 is disposed on the inner peripheral side of the outer rotor 11 having internal teeth. Yes.

  The pump plate 14 is provided with a suction port (suction port) and a discharge port (discharge port) (not shown) that protrude from the end face and penetrate in the axial direction. The suction port and the discharge port are connected to an external hydraulic pipe (not shown), and hydraulic oil flows from the suction oil passage through the discharge oil passage.

  The motor housing 17 has a cylindrical shape, and a front end thereof is fixed to a portion near the outer periphery of the rear surface of the pump housing 15 via a seal 30. The rear end opening of the motor housing 17 is closed by the cover 20. The motor housing 17 and the cover 20 are in contact with the fixed motor housing 17 while rotating the cover 20, and are welded together (for example, spin welding) by frictional heat generated by the rotation. Here, at the center of the cover 20, for example, a circular breathing hole 29 that communicates the space between the outside and the inside of the motor housing 17 is provided.

  A cylindrical portion having a smaller diameter than the motor housing 17 is integrally formed at the center of the rear end surface of the pump housing 15, and the rotating shaft of the electric motor 3 extends in the front-rear direction by bearings 23 and 24 provided at the rear portion in the cylindrical portion. A motor shaft 7 is cantilevered. In the present embodiment, the bearings 23 and 24 are ball bearings which are two rolling bearings adjacent to the front and rear, the inner rings of the bearings 23 and 24 are fixed to the rotating shaft 7, and the outer rings are fixed to the cylindrical portion. Yes. An oil seal 25 is provided between the portions in front of the bearings 23 and 24 in the cylindrical portion and the rotary shaft 7. The front portion of the rotary shaft 7 penetrates through a hole formed in the rear wall of the pump housing 15 and enters the pump chamber 13, and the tip thereof is rotatably connected to the inner rotor 12.

  A rotor 6 constituting the electric motor 3 is fixed to a rear end portion of the rotating shaft 7 protruding rearward from the cylindrical portion of the pump housing 15. The rotor 6 is formed in a cylindrical shape extending in the radial direction from the rear end of the rotating shaft 7 and surrounding the outer periphery of the bearings 23 and 24, and a plurality of permanent magnets (segment magnets) 8 are fixed to the outer periphery. More specifically, the rotor 6 includes a perforated disc portion 27 of the rotor body (hereinafter referred to as a back yoke) 10 and a rotor cylindrical portion 28 integrally formed on the outer periphery thereof, and the inner periphery of the disc portion 27. Is fixed to the rotary shaft 7, and the permanent magnet 8 is provided on the outer periphery of the rotor cylindrical portion 28. The rotary shaft 7 is fixed by press-fitting into a circular through hole 31 formed in the disc portion 27. The axial position of the center of gravity of the rotating portion including the rotary shaft 7, the rotor 6 and the inner rotor 12 of the oil pump 2 is within the axial range of the bearings 23 and 24. In the present embodiment, the axial position of the center of gravity is between the two ball bearings constituting the bearings 23 and 24.

  A stator 5 constituting the electric motor 3 is fixedly provided on the inner periphery of the motor housing 17 facing the rotor 6 through a slight air gap. In the stator 5, an insulator 18, which is an insulating member made of synthetic resin, is mounted on a stator core 9 made of laminated steel plates, and a coil 19 is wound around the insulator 18. In the present embodiment, the stator 5 is fixed to the inner periphery of the motor housing 17 with an adhesive or the like on the outer periphery of the stator core 9.

  A control board 26 of the controller 4 is fixed to the rear end of the insulator 18, and electronic components (for example, a microcomputer, IC, capacitor, coil, etc.) 22 constituting the controller 4 are mounted at predetermined positions on the front and rear surfaces of the control board 26. (An example of the electronic component 22 attached to the rear surface of the control board 26 is shown in the figure). The control board 26 is mounted with an inverter circuit that converts a direct current power source into alternating current and supplies a drive current to each coil 19 of the electric motor 3 and a control circuit that controls the inverter circuit.

  Thus, when the rotating shaft 7 is rotationally driven by the electric motor 3, the inner rotor 12 rotates. Then, the outer rotor 11 rotates following the inner rotor 12, and the volume of the gap between the inner teeth of the outer rotor 11 and the outer teeth of the inner rotor 12 repeats expansion and contraction. As a result, a pumping operation is performed in which hydraulic oil is sent from the suction port toward the discharge port via the suction and discharge oil passages that lead to these gaps.

Next, FIG. 2 is a plan view of the rotor 6 of the electric motor 3 as seen from the AA direction in FIG.
As shown in FIG. 2, the rotor 6 is provided with a synthetic resin-made permanent magnet holding member 33 on the outer periphery of a cylindrical back yoke 10, and is divided into a plurality of locations (this embodiment) that equally divides the permanent magnet holding member 33 in the circumferential direction. In the embodiment, segment-shaped permanent magnets 8 are arranged at eight locations, and are held in contact with the outer peripheral surface of the back yoke 10.

  The permanent magnet holding member 33 is integrally formed by molding a synthetic resin on the outer peripheral portion of the rotor cylindrical portion 28 (see FIG. 1) of the back yoke 10 using a mold. The permanent magnet holding member 33 is connected to the annular portion 34 that is in close contact with the outer peripheral portions of both end surfaces of the rotor cylindrical portion 28, and the two annular portions 34 extending in the axial direction on the outer peripheral surface of the rotor cylindrical portion 28. And a rod-shaped connecting portion 35 for holding the. The connecting portion 35 is formed at a plurality of locations (eight locations in the present embodiment) that equally divide the annular portion 34 in the circumferential direction on the front side in the rotational direction indicated by an arrow. The connecting portion 35 has a portion extending obliquely to the rear side in the rotational direction on the outer side in the radial direction from the annular portion 34, and a permanent magnet holding member claw portion projecting in the circumferential direction on the tip portion on the opposite side in the rotational direction of this portion ( A first permanent magnet holding claw portion 36) is integrally formed.

  The back yoke 10 is, for example, a rotor core in which a large number of annular plates made of a soft magnetic material such as iron or an electromagnetic steel plate are laminated and integrally connected in a ring shape. A circular through hole 31 that is fixed through the rotating shaft 7 (see FIG. 1) of the electric motor 3 is formed in the disk portion 27 (see FIG. 1) of the back yoke 10. In the present embodiment, the through hole 31 is formed. Two key grooves 32 are provided at two symmetrical positions of the through hole 31.

  A portion of the back yoke 10 that forms a substantially V-shaped cross section between the connecting portion 35 and the connecting portion 35 that extends diagonally outward in the radial direction from the annular portion 34 to the rear side in the rotational direction indicated by an arrow. A back yoke claw portion (second permanent magnet holding claw portion) 37 projecting in the circumferential direction is integrally formed at the tip portion in the rotational direction of this portion. And the permanent magnet 8 is inserted and hold | maintained from the axial direction front side between this permanent magnet holding member claw part 36 of the connection part 35 adjacent to this back yoke claw part 37. FIG.

  Here, when the back yoke claw portions 37 integrated with the back yoke 10 are formed on both sides in the axial direction of the permanent magnet 8, the N pole and the S pole of the adjacent permanent magnet 8 form the metal back yoke claw portions 37. Accordingly, the magnetic path of the magnetic flux of the permanent magnet 8 passing through the back yoke 10 is not formed and the number of magnetic fluxes of the back yoke 10 and the permanent magnet 8 is reduced. For this reason, by providing the back yoke claw portion 37 integrally with the back yoke 10 only on one side (one side) of the permanent magnet 8, it is possible to suppress a decrease in motor output torque and motor efficiency.

  Further, if the back yoke claw portion 37 is a back yoke 10 having a structure formed by laminating thin plates such as electromagnetic steel plates, even if it is a petal (substantially V-shaped) shape as in this embodiment, it can be easily obtained. Processing and production are possible.

Next, FIG. 3 is a perspective view of the back yoke 10 and the permanent magnet holding member 33 of the rotor 6 of the electric motor 3 in FIG. 1 as viewed from the front side in the axial direction.
As shown in FIG. 3, the back yoke claw portion 37 is formed over the entire length in the axial direction of the back yoke 10, and between the adjacent permanent magnet holding member claw portions 36 formed on the permanent magnet holding member 33. Permanent magnets 8 (not shown, see FIG. 2) are arranged to hold both sides in the axial direction. Further, when the permanent magnet holding member 33 is integrally formed on the outer peripheral portion of the back yoke 10, the key groove 32 provided in the through hole 31 can be used for phase alignment.

Next, FIG. 4 is a longitudinal sectional view of the rotor 6 of the electric motor 3 according to the second embodiment of the present invention.
As shown in FIG. 4, the back yoke claw portion 39 has a predetermined length from both ends in the axial direction of the back yoke 10, and is divided and arranged at two locations. A permanent magnet holding member claw portion 38 is formed between the two back yoke claw portions 39 to hold one side in the axial direction on the rear side in the rotation direction of the permanent magnet 8. One side in the axial direction on the front side in the rotation direction of the permanent magnet 8 is held by the permanent magnet member claw portion 36.

  Next, operations and effects of the rotor 6 and the electric motor 3 according to the present embodiment configured as described above will be described.

  According to the first embodiment, the rotational direction front side of the rotor 6 formed on the synthetic resin permanent magnet holding member 33 integrally formed on the outer peripheral portion of the back yoke (rotor main body) 10 adjacent in the circumferential direction. The permanent magnet holding member claw portion (first permanent magnet holding claw portion) 36 and the back yoke claw portion (second permanent magnet) on the rear side in the rotation direction of the rotor 6 formed integrally with the metal back yoke 10. The permanent magnet 8 is held in contact with the outer peripheral surface of the back yoke 10 without using an adhesive between a plurality of locations (eight locations in the present embodiment) and the magnet holding claw portion 37. As a result, even if an oblique rearward (radially outward) force is applied to the rear side in the rotational direction of the permanent magnet due to the rotation of the rotor 6, the permanent magnet 8 does not peel off from the back yoke 10 in the radial direction and does not fall off. 8 can be securely fixed to the back yoke 10.

  Further, since the back yoke claw portion 37 formed integrally with the back yoke 10 is provided over the entire length in the axial direction, when the back yoke 10 is formed by a laminated structure of a large number of annular plates such as electromagnetic steel plates, the annular plate The die and the molding process can be simplified, the back yoke 10 can be easily processed, and can be manufactured at low cost.

  According to the second embodiment, since the back yoke claw portion 37 is divided and arranged at both ends in the axial direction, the back yoke 10 is reduced in weight and the permanent magnet is reliably secured by the metal back yoke claw portion 37. Can be held in.

  The electric motor 3 including the rotor 6 according to the first and second embodiments can securely fix the permanent magnet 8 to the back yoke 10 with a structure that does not use an adhesive. It is easy to process and can be manufactured at low cost.

  As described above, according to the present embodiment, it is possible to provide a rotor and an electric motor that can be fixed at a low cost because the permanent magnet is securely fixed to the back yoke, and the back yoke can be easily processed.

  While the first and second embodiments according to the present invention have been described above, the present invention can be implemented in other forms.

  In the above embodiment, the case where the back yoke 10 is formed by a laminated structure such as an electromagnetic steel plate has been described. However, the present invention is not limited to this, and the back yoke 10 is formed by another configuration (for example, a sintered body). Also good.

  In the above embodiment, the permanent magnet holding member claw portion 36 and the back yoke claw portion 37 are formed so as to have a substantially V-shaped cross section. However, the present invention is not limited to this, and both the claw portions 36 and 37 are formed. The outer periphery may be formed in a cylindrical shape.

  In the second embodiment, the back yoke claw portion 37 is divided and arranged at two positions on both ends in the axial direction of the back yoke 10. However, the present invention is not limited to this and is divided into three or more locations. Thus, the weight may be reduced.

  The overall configuration of the electric oil pump device 1 and the configuration of each unit are not limited to those of the above-described embodiment, and can be appropriately changed.

  For example, in the above embodiment, the brushless motor in which the rotating shaft 7 is cantilevered as the electric motor 3 that rotationally drives the oil pump 2 has been described as an example. However, the present invention is not limited to this, and both ends of the rotating shaft 7 are supported. The brushless motor may be supported by bearings inside the pump housing 15 and the motor housing 17.

  Moreover, although the case where a trochoid pump was used as an internal gear pump was shown in the said embodiment, it is not limited to this, The inner rotor 12 which provided the internal tooth on the inner peripheral side of the outer rotor 11, and was provided with the external tooth The internal gear pump may be any internal gear pump in which the volume of the gap partitioned by the inscribed portion between the outer rotor 11 and the inner rotor 12 repeats expansion and contraction by rotating eccentrically while meshing. Further, the inner teeth of the outer rotor 11 and the outer teeth of the inner rotor 12 are not necessarily formed in a clear so-called tooth shape, and may be protrusions, protrusions, or engaging portions.

  In the above embodiment, the rotor 6 of the electric motor 3 applied to the electric oil pump device 1 has been described. However, the present invention is not limited to this and can be applied to electric motors other than the electric oil pump device for automobiles.

1: electric oil pump device, 2: oil pump, 3: electric motor, 4: controller,
5: stator, 6: rotor, 7: rotating shaft, 8: permanent magnet, 9: stator core,
10: Back yoke (rotor body), 11: Outer rotor, 12: Inner rotor,
13: Pump chamber, 14: Pump plate, 15: Pump housing, 16: O-ring,
17: Motor housing, 18: Insulator, 19: Coil, 20: Cover,
21: Control room, 22: Electronic component, 23, 24: Bearing, 25: Oil seal,
26: Control board, 27: Disk part, 28: Rotor cylindrical part, 29: Breathing hole, 30: Seal,
31: Through-hole, 32: Keyway, 33: Permanent magnet holding member, 34: Ring part, 35: Connection part, 36, 38: Permanent magnet holding member claw part (first permanent magnet holding claw part),
37, 39: Back yoke claw portion (second permanent magnet holding claw portion)

Claims (4)

A cylindrical rotor body;
A permanent magnet holding member made of synthetic resin provided in a fixed manner on the outer periphery of the rotor body;
A plurality of permanent magnets in contact with the outer peripheral surface of the rotor main body and held by the permanent magnet holding member;
The permanent magnet holding member includes an annular portion that is in close contact with outer peripheral portions of both end surfaces of the rotor body, and a connecting portion that connects the annular portions on the outer peripheral surface of the rotor body and holds the permanent magnet. A plurality of first permanent magnet holding claws that are integrally formed by projecting to the front side in the rotational direction of the rotor body in the circumferential direction at a portion extending radially outward from the annular portion of the connecting portion. ,
The rotor body has a plurality of second permanent magnet holding claws that are integrally formed by projecting to the rear side in the rotation direction of the rotor body in the circumferential direction on a portion extending radially outward on the outer peripheral surface;
The rotor is characterized in that the permanent magnet is held between the first permanent magnet holding claw portion and the second permanent magnet holding claw portion which are adjacent in the circumferential direction. The rotor according to claim 1, wherein
The second permanent magnet holding claw is formed over the entire length in the axial direction. The rotor according to claim 1, wherein
The second permanent magnet holding claw portion is formed to have a predetermined length from both ends in the axial direction.   An electric motor comprising the rotor according to any one of claims 1 to 3.

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