JP2009022128A - Ipm motor, manufacturing method therefor, and electric power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IPM motor and a manufacturing method therefor, capable of attaining improvement of output torque, and to provide an electric power steering system therewith. <P>SOLUTION: In this IPM motor 10, a magnetic square pillar-shaped spacer 40 is inserted in a gap 27 between a permanent magnet 30 and a slant inner side surface 25 in a magnet embedding hole 23 while the permanent magnet 30 is brought into surface contact with a wide inner side surface 24 of the magnet embedding hole 23, and the square pillar-shaped spacer 40 is moved in the gap 27 in a direction orthogonal to an insertion direction. Then, the square pillar-shaped spacer 40 is brought into surface contact with the permanent magnet 30 and the slant inner side surface 25. Therefore, it is possible to eliminate an air gap between the permanent magnet 30 and the magnet embedding hole 23 in a direction in which flux penetrates (a direction orthogonal to a pair of wide outer side surfaces 31, 32) even if a dimensional error exists in the permanent magnet 30, thus attaining improvement of the output torque without enlarging the IPM motor 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an IPM (Interior Permanent Magnet) motor in which a strip-shaped permanent magnet is fixed in a plurality of magnet embedding holes extending in the axial direction of a rotor yoke, a manufacturing method thereof, and the IPM motor. The present invention relates to an electric power steering apparatus provided.

As this type of conventional IPM motor, a permanent magnet is fixed in the magnet embedding hole by arranging the spacer in an elastically deformed state in the gap between the permanent magnet and the magnet embedding hole. (For example, refer to Patent Document 1).
Japanese Unexamined Patent Publication No. 2004-120829 (paragraph [0021], FIG. 1)

  However, in the conventional IPM motor described above, since the spacer is a non-magnetic material, the air gap exists in the magnetic flux penetrating direction (permanent magnet thickness direction), and the magnetic flux is effectively used. Can not do it. That is, the permeance coefficient is reduced (the magnetic resistance is increased), and the magnetic flux density at the operating point of the permanent magnet is reduced, so that the output torque cannot be improved.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an IPM motor capable of improving output torque, a method for manufacturing the same, and an electric power steering apparatus including the IPM motor.

  In order to achieve the above object, an IPM motor (10) according to the invention of claim 1 includes a strip-shaped permanent magnet (23) in a plurality of magnet embedded holes (23) formed in the rotor yoke (21). 30) is fixed, and each permanent magnet (30) is magnetized so that the magnetic flux passes through a pair of wide outer surfaces (31, 32) of the outer surfaces of each permanent magnet (30). In (10), each magnet embedding hole (23) has a wide inner surface (24) in which the entire one wide outer surface (31) of each permanent magnet (30) is in surface contact, and each permanent magnet (30). ) And an inclined inner side surface (25) that is opposed to and inclined with respect to the other wide outer surface (32), and the other wide outer surface (32) of the permanent magnet (30) and the magnet embedding hole (23). The other wide outer surface (32) and the inclined inner surface are between the inclined inner surface (25). Having characterized in that the dihedral prism spacers abutting magnetic (40) is inserted (25).

  According to a second aspect of the present invention, in the IPM motor (10) according to the first aspect, the wide inner surface (24) is wider than the wide outer surface (31, 32), and the outer surface of the permanent magnet (30) is Between the pair of narrow outer surfaces (33, 33) and the pair of narrow outer surfaces (33, 33) and the inner surfaces (26, 26) of the magnet embedding hole (23) facing each other, It is characterized by providing clearances (28, 28) for restricting the passage of magnetic flux.

  According to a third aspect of the present invention, in the IPM motor (10) according to the second aspect of the present invention, the center in the width direction of the wide inner surface (24) is depressed with the same width as the wide outer surface (31, 32), and the permanent magnet It is characterized in that a positioning concave portion (29) in which one end portion in the plate thickness direction of (30) engages with the concave and convex portions is formed.

  According to a fourth aspect of the present invention, in the IPM motor (10) according to the second or third aspect, of the prismatic spacer (40), the other wide outer surface (32) of the permanent magnet (30) and the magnet embedding hole ( 23) of the wedge base end side surface (43) which is the side surface having the widest distance from the inclined inner side surface (25), and the magnet embedding holes (23) facing the wedge base end side surface (43). It is characterized in that a spacer movement prohibiting member (45) for restricting the movement of the prism spacer (40) is disposed between the inner surface (26).

  An electric power steering apparatus (100) according to a fifth aspect of the invention steers the IPM motor (10) according to any one of the first to fourth aspects of the invention according to the first aspect of the invention, and the steered wheels (101, 101) of the vehicle (110). It is characterized in that it is provided as a power source for assisting the steering force required for steering operation at the time.

  The manufacturing method of the IPM motor (10) according to the invention of claim 6 comprises a rotor yoke (21) formed by laminating a plurality of circular steel plates (21A), and press holes formed by punching each circular steel plate (21A) ( 23A) is communicated between the circular steel plates (21A) to form a plurality of magnet embedded holes (23) in the rotor yoke (21), and a strip-shaped permanent magnet is formed inside each of the magnet embedded holes (23). A method of manufacturing an IPM motor (10) provided with (30) fixed, wherein the cross-sectional shape of each magnet embedding hole (23) is a trapezoid with one side of the rectangle as a hypotenuse, and each magnet embedding The permanent magnet (30) is brought into contact with the wide inner surface (24) corresponding to the opposite side of the oblique side of the hole (23), and then the permanent magnet (30) and each magnet embedded hole ( 23) between the inclined inner surface (25) corresponding to the hypotenuse A prismatic spacer (40) having a prismatic structure is inserted, the prismatic spacer (40) is brought into surface contact with the permanent magnet (30) and the inclined inner side surface (25), and a press hole (23A) is formed from the circular steel plate (21A). ), The trapezoid which is the sectional shape of each magnet embedding hole (23) is divided into a right triangle including a hypotenuse and a quadrangle, and a steel plate piece (40A) having a right triangle is formed. A feature is that the prisms (40) are formed by stacking the pieces (40A).

[Invention of Claim 1]
According to the first aspect of the present invention, the IPM motor includes the other wide outer surface of the permanent magnet and the inclined inner surface of the magnet embedding hole in a state where the strip-shaped permanent magnet is disposed inside the magnet embedding hole. A prismatic spacer made of a magnetic material is inserted into the gap between them, and the prismatic spacer is moved in the gap in a direction perpendicular to the insertion direction. Specifically, the prism spacer is moved from the wide side between the permanent magnet and the inclined inner side surface of the magnet embedding hole to the narrow side. Then, the prism spacer contacts the entire other wide outer surface of the permanent magnet and the inclined inner side surface of the magnet embedding hole, and the entire one outer side surface of the permanent magnet becomes the wide inner surface of the magnet embedding hole. In addition to the surface contact, the gap between the other wide outer surface of the permanent magnet and the inclined inner surface of the magnet embedding hole is closed by the prismatic spacer of the magnetic material. Thereby, even if there is a dimensional error in the permanent magnet, the air gap between the permanent magnet and the magnet embedding hole in the direction in which the magnetic flux penetrates (that is, the direction orthogonal to the pair of wide outer surfaces) can be eliminated. The magnetic flux can be used effectively. Therefore, it is possible to improve the output torque without increasing the size of the IPM motor.

[Invention of claim 2]
According to the second aspect of the present invention, the clearances for restricting the passage of the magnetic flux are respectively formed on the sides of the pair of narrow outer surfaces among the outer surfaces of the permanent magnets. It is possible to prevent so-called magnetic flux leakage such that the magnetic flux extends in a loop, or the magnetic flux extends in a loop between a pair of wide outer surfaces of the permanent magnet. Thereby, the output torque can be improved.

[Invention of claim 3]
According to the invention of claim 3, the movement of the permanent magnet in the direction orthogonal to the pair of narrow outer surfaces is prohibited, and the clearance can be reliably maintained.

[Invention of claim 4]
According to the invention of claim 4, during the operation of the IPM motor, it is possible to prevent rattling of the permanent magnet and the formation of an air gap due to the movement of the prism spacer.

[Invention of claim 5]
According to the electric power steering apparatus of the fifth aspect, it is possible to improve the assist torque, and it is possible to mount on a larger vehicle.

[Invention of claim 6]
According to invention of Claim 6, when the press hole used as a magnet embedding hole is punched in the circular steel plate which comprises a rotor yoke in the state which laminated | stacked them, the steel plate piece pierced from the circular steel plate is laminated | stacked, and a prism is stacked. Since the spacer is formed, the circular steel plate can be effectively used without waste, and the material cost can be suppressed.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The IPM motor 10 of the present embodiment is a brushless motor, for example, and includes a rotor 20 at the center of the stator core 11. The stator core 11 has a structure in which a plurality of (for example, twelve) teeth 13 protrude inward from the inner peripheral surface of the cylindrical body, and an electric wire 14 is wound around each tooth 13.

  As shown in FIG. 3, the rotor 20 is configured such that, for example, the center of a columnar rotor yoke 21 formed by laminating a plurality of disk-shaped silicon steel plates 21A (corresponding to “circular steel plates” of the present invention) is the rotor shaft 22. The structure has penetrated. As shown in FIG. 2, a plurality of field permanent magnets 30 are embedded in the rotor yoke 21 in an annular shape along the outer peripheral edge thereof. Specifically, a plurality of magnet embedded holes 23 extend in the axial direction of the rotor 20 along the outer peripheral edge of the rotor yoke 21 (see FIG. 3), and a strip-shaped permanent magnet 30 is formed in the magnet embedded holes 23. Are inserted. In the present embodiment, the plurality of magnet embedding holes 23 are arranged so that the circumferential direction of the rotor yoke 21 is, for example, 10 or so.

  As shown in FIG. 2, the permanent magnet 30 has a rectangular cross section viewed from the axial direction of the rotor 20. That is, it has a pair of wide outer surfaces 31 and 32 corresponding to a pair of long sides in a rectangle and a pair of narrow outer surfaces 33 and 33 corresponding to a pair of short sides in a rectangle. The wide outer surfaces 31 and 32 are arranged so as to be orthogonal to the radial direction of the rotor 20. The permanent magnet 30 is magnetized so that magnetic flux penetrates the pair of wide outer surfaces 31 and 32 (magnetic flux penetrates in the thickness direction of the permanent magnet 30). One of these wide outer surfaces 31, 32, specifically, the wide outer surface 31 disposed on the radially outer side of the rotor 20 is in surface contact with the inner surface of the magnet embedding hole 23 described in detail below. In this state, it is fixed inside the magnet embedding hole 23.

  FIG. 4 shows a planar shape of the magnet embedding hole 23 viewed from the axial direction of the rotor 20. As shown in the figure, the magnet embedding hole 23 is arranged on the outer side in the radial direction of the rotor 20, and as described above, the entire inner surface 24 of the one wide outer surface 31 of the permanent magnet 30 is in contact with the wide inner side surface 24. The inner surface of the rotor 20 is disposed on the inner side in the radial direction, and the inner surface 25 of the permanent magnet is disposed opposite the wide outer surface 32 of the permanent magnet. The wide inner side surface 24 is constituted by a flat surface orthogonal to the radial direction of the rotor 20, while the inclined inner side surface 25 is constituted by a flat surface inclined at a predetermined angle θ1 with respect to the wide inner side surface 24.

  Both ends of the wide inner side surface 24 and the inclined inner side surface 25 are connected by a pair of narrow inner side surfaces 26, 26 intersecting the wide inner side surface 24 at right angles. That is, of the narrow inner side surfaces 26, 26, one narrow inner side surface 26 intersects with the inclined inner side surface 25 to form an acute angle, and the other narrow inner side surface 26 intersects with the inclined inner side surface 25 to form an obtuse angle. Form.

  The permanent magnet 30 and the magnet embedding hole 23 described above are formed by inserting the permanent magnet 30 into the magnet embedding hole 23 as shown in FIG. The gap 27 is sized so that a gap 27 is formed between the other wide outer side surface 32 of the permanent magnet 30 and the inclined inner side surface 25 of the magnet embedding hole 23 in a state of being in surface contact with the wide inner side surface 24 of the insertion hole 23. It has become. The gap 27 has a wedge shape that narrows from one side in the circumferential direction of the rotor 20 toward the other side (from one of the pair of narrow inner surfaces 26 and 26 to the other). The prismatic spacer 40 according to the present invention is inserted and fitted into the gap 27.

  As shown in FIG. 5A, the prism spacer 40 is formed by laminating a plurality of silicon steel plates in the same manner as the rotor yoke 21, and in this embodiment, for example, has a triangular prism shape. As shown in FIG. 5B, the planar shape of the prism spacer 40 viewed from the axial direction of the rotor 20 forms a right triangle having three different lengths, and the right side triangle corresponds to the hypotenuse of the right triangle. An angle θ2 formed by the contact inclined surface 41 and the contact wide surface 42 corresponding to the long side is an angle θ1 formed by the wide inner surface 24 and the inclined inner surface 25 in the magnet embedded hole 23 (see FIG. 4A). ) And the same angle.

  Then, as shown in FIG. 6C, the wide contact surface 42 of the prismatic spacer 40 is in surface contact with the entire surface of the other wide outer surface 32 of the permanent magnet 30, and the contact inclined surface 41 of the prismatic spacer 40 is in contact. The entire surface is in surface contact with the inclined inner side surface 25 of the magnet embedding hole 23. As a result, one wide outer surface 31 of the permanent magnet 30 disposed on the radially outer side of the rotor 20 is pressed against the wide inner surface 24 of the magnet embedding hole 23, and the rotor 20 of the permanent magnet 30. A gap 27 between the other wide outer surface 32 arranged on the inner side in the radial direction and the inclined inner surface 25 of the magnet embedding hole 23 is closed by a prismatic spacer 40 made of a magnetic material. In this state, the contact inclined surface 41 and the inclined inner surface 25 are fixed with an adhesive, and the movement of the prism spacer 40 within the gap 27 is prohibited. Thereby, during the operation of the IPM motor 10, the rattling of the permanent magnet 30 and the formation of the air gap due to the movement of the prismatic spacer 40 can be prevented, and the reduction of torque ripple and output torque can be prevented. it can.

  During the operation of the IPM motor 10, that is, during the rotation of the rotor 20, a centrifugal force is applied to the permanent magnet 30 and the prismatic spacer 40, and the permanent magnet 30 can be pressed against the wide inner surface 24 by this centrifugal force. it can.

  As shown in FIG. 6C, clearances (air gaps) 28, 28 are provided between the narrow outer side surfaces 33, 33 of the permanent magnet 30 and the narrow inner side surfaces 26, 26 of the magnet embedding hole 23, respectively. Is formed. The clearances 28, 28 prevent so-called magnetic flux leakage such that magnetic flux extends between the permanent magnets 30, 30 adjacent in the circumferential direction, or magnetic flux extends in a loop shape between the wide outer surfaces 31, 32 of the permanent magnet 30. Can be prevented.

  In order to maintain the clearances 28, a positioning recess 29 is formed on the wide inner side surface 24 of the magnet embedding hole 23. As highlighted in FIG. 4A, the positioning recess 29 has a center in the width direction of the wide inner surface 24 that is the same width as the wide outer surfaces 31, 32 of the permanent magnet 30 and the permanent magnet 30. It is made to sink into a stepped shape smaller than the plate thickness. When one side in the plate thickness direction of the permanent magnet 30 (the wide outer surface 31 side) is fitted into the positioning recess 29, the permanent magnet is placed on both step portions 29A and 29A formed on both sides of the positioning recess 29. When the 30 narrow outer surfaces 33 and 33 come into contact with each other (see FIG. 6C), movement of the permanent magnet 30 in the longitudinal direction is prohibited. That is, the permanent magnet 30 is positioned with the clearances 28, 28 formed between the narrow outer surfaces 33, 33 of the permanent magnet 30 and the narrow inner surfaces 26, 26 of the magnet embedding hole 23. The As a result, the permanent magnet 30 is prohibited from moving inside the magnet embedding hole 23 during the operation of the IPM motor 10, and the clearances 28 and 28 can be reliably maintained. The actual positioning recess 29 is only slightly depressed, and the cross-sectional shape of the magnet embedding hole 23 can be regarded as a trapezoid with one side of the rectangle as a hypotenuse.

  By the way, the magnet embedding hole 23 has a trapezoidal press hole 23A (see FIG. 4 (B)) formed by punching each silicon steel plate 21A (see FIG. 2) constituting the rotor yoke 21 in the thickness direction. In the laminated state of 21A, it is formed so as to communicate with the lamination direction.

  Each press hole 23A is punched by being divided into a plurality of punching steps. Specifically, the first step of punching out a radially outward portion 23A1 of the silicon steel plate 21A into a rectangular shape (exactly, a flat convex shape), and the radially inward portion 23A2 into the magnet embedded hole 23 The second step of punching into a right triangle including a trapezoidal hypotenuse having the cross-sectional shape of FIG. 5 and the third step of punching the remaining portion 23A3 are punched. And the prismatic spacer 40 which concerns on this embodiment is formed by laminating | stacking the steel plate piece 40A of the right-angled triangle which generate | occur | produced when punching out part 23A2 radially inward (refer FIG. 5 (A)). . Thereby, the silicon steel plate 21A can be used effectively, and the material cost can be suppressed.

  As shown in FIG. 5, each steel plate piece 40A is formed with a locking projection 40A1 by pressing a part of the steel plate piece 40A in the thickness direction, and is formed on the back side of the locking projection 40A1. The plurality of steel plate pieces 40A are held in a stacked state by pushing the locking projections 40A1 of the other steel plate pieces 40A into the locking recesses (not shown). That is, a plurality of steel plate pieces 40A can be held in a stacked state as shown in FIG. 5A without using another component or an adhesive for maintaining the stacked state.

  The above is the description regarding the structure of the IPM motor 10 in the present embodiment, and the method for assembling the permanent magnet 30 to the rotor yoke 21 will be described below.

  First, the permanent magnet 30 is inserted into the magnet embedding hole 23 from one end of the rotor yoke 21 in the axial direction, and is fitted into the positioning recess 29 of the wide inner surface 24 (see FIG. 6A). In this state, the prism spacer 40 is inserted from the axial direction of the rotor yoke 21 into the gap 27 formed between the other wide outer surface 32 of the permanent magnet 30 and the inclined inner surface 25 of the magnet embedding hole 23. At this time, as shown in FIG. 6 (B), a prism is placed on the side where the distance between the wide outer surface 32 of the permanent magnet 30 and the inclined inner surface 25 of the magnet embedding hole 23 is wide (the left side in FIG. 6 (B)). By inserting the spacer 40 while being shifted, the insertion work of the prismatic spacer 40 can be performed smoothly. When the prism spacer 40 is inserted, the prism spacer 40 is inserted in a direction orthogonal to the insertion direction, specifically, the side where the distance between the wide outer surface 32 and the inclined inner surface 25 is wide from the narrow side (FIG. 6B). Move to the right).

  As the prism spacer 40 is moved, the tip (the corner where the contact inclined surface 41 and the contact wide surface 42 intersect) bites between the edge of the permanent magnet 30 and the inclined inner surface 25. The wide contact surface 42 of the prism spacer 40 is in surface contact with the other wide outer surface 32 of the permanent magnet 30, and the contact inclined surface 41 of the prism spacer 40 faces the inclined inner surface 25 of the magnet embedding hole 23. The prism spacer 40 is stuck due to contact (see FIG. 6C). Then, one wide outer surface 31 of the permanent magnet 30 is pressed in a state of being in surface contact with the wide inner surface 24 of the magnet embedding hole 23, and formed between the wide outer surface 32 and the inclined inner surface 25. The gap 27 is closed by the prism spacer 40. In this state, the contact inclined surface 41 and the inclined inner side surface 25 are bonded by an adhesive previously applied to at least one of the contact inclined surface 41 of the prism spacer 40 and the inclined inner side surface 25 of the magnet embedding hole 23. Is fixed. As a result, the permanent magnet 30 is inserted into the magnet embedded hole in a state in which the air gap between the permanent magnet 30 and the magnet embedded hole 23 is eliminated in the direction in which the magnetic flux penetrates (the direction orthogonal to the wide outer surfaces 31 and 32). 23 is fixed inside. Thus, the rotor 20 is completed. The rotor 20 is inserted into the stator 11 as shown in FIG. 1, and the rotor shaft 22 is pivotally supported by a bearing (not shown) to complete the IPM motor 10.

  Thus, in the IPM motor 10 of the present embodiment, when the permanent magnet 30 is fixed in the magnet embedding hole 23, the permanent magnet 30 is brought into surface contact with the wide inner side surface 24 of the magnet embedding hole 23. In this state, a magnetic prism spacer 40 is inserted into a gap 27 between the other wide outer surface 32 of the permanent magnet 30 and the inclined inner surface 25 of the magnet embedding hole 23, and the prism spacer 40 is inserted into the gap 27. Move in a direction orthogonal to the insertion direction. Specifically, the prism spacer 40 is moved from the wide side between the permanent magnet 30 and the inclined inner surface 25 in the magnet embedding hole 23 to the narrow side. Then, the contact wide surface 42 of the prismatic spacer 40 is in surface contact with the entire surface of the wide outer surface 32 of the permanent magnet 30, and the contact inclined surface 41 of the prismatic spacer 40 is in contact with the inclined inner side surface 25 of the magnet embedding hole 23. The wide outer side surface 31 of the permanent magnet 30 is pressed against the wide inner side surface 24 in the magnet embedding hole 23 in contact with each other. Further, the gap 27 between the permanent magnet 30 and the inclined inner side surface 25 is closed by the magnetic prism spacer 40. Thereby, even if there is a dimensional error in the permanent magnet 30, the air gap between the permanent magnet 30 and the magnet embedding hole 23 in the direction in which the magnetic flux penetrates (the direction perpendicular to the pair of wide outer surfaces 31 and 32). Can be eliminated. Therefore, it is possible to improve the output torque without increasing the size of the IPM motor 10.

  Further, in the conventional IPM motor that fixes the permanent magnet in the magnet embedding hole by disposing the elastic spacer in the gap between the permanent magnet and the magnet embedding hole in an elastically deformed state, Although the workability is poor because it must be inserted into the gap while being deformed, in the IPM motor 10 of this embodiment, the prismatic spacer 40 is inserted into the gap 27 between the permanent magnet 30 and the magnet embedding hole 23. Therefore, since the permanent magnet 30 can be fixed by moving the gap 27 in the direction orthogonal to the insertion direction, the workability is improved as compared with the conventional case.

  Next, an electric power steering apparatus 100 using the IPM motor 10 will be described. As shown in FIG. 7, the electric power steering apparatus 100 includes a shaft 102 between steered wheels passed between a pair of steered wheels 101, 101 provided in a vehicle 110, and an outer side of the shaft 102 between steered wheels. And a shaft case 103 covering the. Both ends of the shaft 102 between the steered wheels are connected to the steered wheels 101 and 101 via tie rods 102T and 102T, and the shaft case 103 is fixed to the main body of the vehicle 110. In addition, a rack (not shown) is formed at an intermediate portion of the inter-steering wheel shaft 102, and a pinion (not shown) penetrating the intermediate portion of the shaft case 103 from the side meshes with the rack.

  An intermediate shaft 105 (hereinafter referred to as “intermediate shaft 105”) is connected to the upper end portion of the pinion, a steering shaft 106 is connected to the upper end portion of the intermediate shaft 105, and further to the upper end portion of the steering shaft 106 Is connected to a handle 107. The rotor 20 of the motor 10 is connected to a connecting portion between the intermediate shaft 105 and the steering shaft 106 via a speed reduction mechanism 108. A steering angle sensor 111 and a torque sensor 112 are attached to the steering shaft 106 to detect the steering angle θs of the handle 107 and the steering resistance Tf (load torque) applied to the steering shaft 106. Further, a vehicle speed sensor 113 for detecting the vehicle speed V based on the rotation of the steered wheel 101 is provided in the vicinity of the steered wheel 101. Then, the steering control device 114 drives the motor 10 in accordance with the driving situation based on the detection signals of the steering angle sensor 111, the torque sensor 112, and the vehicle speed sensor 113, thereby assisting the steering operation by the driver with the motor 10. Thus, the steered wheels 101 can be steered.

  According to the electric power steering apparatus 100 of the present embodiment, since the IPM motor 10 described above is provided as a power source for assisting the steering force of the handle 107, the assist torque of the electric power steering apparatus 100 can be improved. Can be mounted on a larger vehicle.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

  (1) In the above embodiment, ten permanent magnets 30 are embedded along the outer peripheral edge of the rotor yoke 21, but the arrangement and number of the permanent magnets 30 in the rotor yoke 21 are not limited thereto. For example, as shown in FIG. 8A, a structure in which four permanent magnets 30 are arranged at right angles to each other may be used. Further, as shown in FIG. 8B, a structure in which two permanent magnets 30, 30 are arranged in a V shape to form one magnetic pole and a plurality of the magnetic poles are equally arranged in the circumferential direction of the rotor 20 may be employed.

  (2) In the above-described embodiment, the prism spacer 40 has a triangular prism shape, and the corner where the contact inclined surface 41 and the contact wide surface 42 intersect is pointed. Before the abutting wide surface 42 abuts against the wide outer surface 32 of the permanent magnet 30, the corner portion where the abutting sloping surface 41 and the abutting wide surface 42 intersect is formed. In order to prevent the magnet embedding hole 23 from striking against the narrow inner side surface 26, as shown in FIG. 9, a corner portion where the contact inclined surface 41 and the contact wide surface 42 intersect each other is eliminated, and a prism spacer. 40 may be trapezoidal in cross section.

  (3) As shown in FIG. 10, in the prism spacer 40, a wedge base end which is the side surface on the side where the distance between the wide outer side surface 32 of the permanent magnet 30 and the inclined inner side surface 25 of the magnet embedding hole 23 is widest. A spacer movement prohibiting member 45 according to the present invention may be disposed between the side surface 43 and the narrow inner side surface 26 of the magnet embedding hole 23 to prohibit the movement of the prismatic spacer 40. Thereby, during the operation of the IPM motor 10, it is possible to prevent rattling of the permanent magnet 30 and generation of an air gap due to the movement of the prismatic spacer 40. The spacer movement prohibiting member 45 may be a resin that is poured and solidified in a fluid state between the wedge base end side surface 43 and the narrow inner side surface 26, or the wedge base end side surface 43 and the narrow inner side surface 26. The elastic member may be compressed and deformed between the two.

  (4) Although the cross section of the permanent magnet 30 of the said embodiment was a rectangle, if it is a flat cross-sectional shape, it will not be limited to a rectangle. For example, the permanent magnet 30 may have a trapezoidal cross section.

  (5) In the embodiment, the rotor 20 is configured by stacking silicon steel plates, but may be configured by stacking iron plates.

  (6) The press hole 23A of the silicon steel plate 21A is formed by a single punching process, and the steel plate pieces generated at that time are formed (sheared) into a right triangle and then stacked to form a prismatic spacer 40. It may be formed.

  (7) The arrangement of the permanent magnets 30 and the prismatic spacers 40 in the magnet embedding holes 23 may be reversed from that in the above embodiment. That is, as shown in FIG. 11, in the magnet embedding hole 23, the prism spacer 40 is disposed on the radially outer side of the rotor yoke 21, the permanent magnet 30 is disposed on the radially inner side, and the permanent magnet 30 is disposed on the radially inner side. The structure pressed against the wide inner surface 24 may be used.

1 is a cross-sectional plan view of an IPM motor according to an embodiment of the present invention. Cross section of rotor Partial sectional side view of the rotor (A) Plan view of magnet embedding hole, (B) Plan view of steel plate piece punched out from silicon steel plate press hole and silicon steel plate (A) Perspective view of prismatic spacer, (B) Plan view of prismatic spacer Top view of rotor in assembly process of permanent magnet and prism spacer Conceptual diagram of electric power steering device Plan sectional view of the rotor of the modified example (1) Plan sectional view of prismatic spacer of modification (2) Partial expanded sectional view of the rotor which concerns on a modification (3) Partial expanded sectional view of the rotor which concerns on a modification (7)

Explanation of symbols

10 IPM motor 21 Rotor yoke 21A Silicon steel plate (round steel plate)
23 Magnet embedded hole 23A Press hole 24 Wide inner surface 25 Inclined inner surface 26, 26 Narrow inner surface 28, 28 Clearance 29 Positioning recess 30 Permanent magnet 31, 32 Wide outer surface 33, 33 Narrow outer surface 40 Rectangular column spacer 40A Steel plate piece 43 Wedge base side surface 45 Spacer movement prohibiting member 100 Electric power steering device 107 Handle

Claims (6)

A strip-shaped permanent magnet is fixed inside a plurality of magnet embedding holes formed in the rotor yoke, and each of the permanent magnets is arranged such that the magnetic flux penetrates a pair of wide outer surfaces among the outer surfaces of the permanent magnets. In an IPM motor magnetized with a permanent magnet,
In each of the magnet embedding holes, a wide inner surface where one entire wide outer surface of each permanent magnet is in surface contact, and an inclined inner surface which is disposed opposite to the other wide outer surface of each permanent magnet and is inclined And formed,
Between the other wide outer surface of the permanent magnet and the inclined inner side surface of the magnet embedding hole, a prismatic spacer of magnetic material that is in surface contact with the entire other outer wide surface and the inclined inner surface. An IPM motor characterized in that is inserted.   The wide inner surface is wider than the wide outer surface, and a pair of narrow outer surfaces among the outer surfaces of the permanent magnet, and an inner surface of the magnet embedding hole facing the pair of narrow outer surfaces. The IPM motor according to claim 1, wherein a clearance for restricting the passage of magnetic flux is provided between the two and the IPM motor.   The center of the wide inner surface in the width direction is depressed with the same width as that of the wide outer surface to form a positioning recess in which one end portion in the plate thickness direction of the permanent magnet engages with each other. 2. The IPM motor according to 2.   Among the prism spacers, a wedge base side surface which is a side surface on which the distance between the other wide outer side surface of the permanent magnet and the inclined inner side surface of the magnet embedding hole is widest, and the wedge base side surface 4. The IPM motor according to claim 2, wherein a spacer movement prohibiting member for restricting the movement of the prismatic spacer is disposed between the inner surface of each of the magnet embedding holes opposed to the magnet. .   An electric power steering system comprising the IPM motor according to any one of claims 1 to 4 as a power source for assisting a steering force required for steering operation when turning a steered wheel of a vehicle. apparatus. A plurality of circular steel plates are laminated to form a rotor yoke, and press holes punched and formed in each of the circular steel plates are communicated between the circular steel plates to form a plurality of magnet embedded holes in the rotor yoke. A method of manufacturing an IPM motor having a strip-shaped permanent magnet fixed inside an embedded hole,
The cross-sectional shape of each magnet embedding hole is a trapezoid with one side of the rectangle as a hypotenuse, and the permanent magnet is applied to the wide inner surface corresponding to the opposite side of the magnet embedding hole to the hypotenuse. After being in contact with each other, a prismatic spacer having a triangular prism structure is inserted between the permanent magnet and the inclined inner surface corresponding to the oblique side of each of the magnet embedding holes, and the prismatic spacer is connected to the permanent magnet. While making surface contact with the inclined inner surface,
When punching out the press hole from the circular steel plate, the trapezoid which is the cross-sectional shape of each magnet embedding hole is divided into a right triangle including the hypotenuse and a rectangle, thereby forming the steel plate piece of the right triangle. And the manufacturing method of the IPM motor characterized by laminating | stacking these steel plate pieces and forming the said prismatic spacer.