JPWO2008059736A1 - Brushless motor - Google Patents

Abstract

The brushless motor 1 includes a magnet holder 51 that includes a magnet holding portion 52 that holds and fixes a magnet, and a resolver rotor connection portion 54 that is connected to the resolver rotor 35. The resolver rotor connecting portion 54 and the resolver rotor 35 are coupled by a resolver coupling portion 63. The resolver coupling portion 63 includes a resolver rotor connecting piece 57 formed in the resolver rotor connecting portion 54 and a fitting groove 66 formed in the resolver rotor 35. The fitting claw 59 of the resolver rotor connecting piece 57 is press-fitted and fixed to the fitting groove 66, and the resolver rotor 35 and the magnet holder 51 are connected in a predetermined angular positional relationship. The rotor shaft 22 is provided with a flange portion 64 for preventing the resolver rotor 35 from coming off.

Description

  The present invention relates to a brushless motor used for an electric power steering apparatus and the like, and more particularly to a structure of a magnet holder that holds a rotor magnet.

  In recent years, many vehicles have been equipped with so-called power steering devices for assisting steering force of automobiles and the like. As such power steering devices, in recent years, vehicles equipped with electric power steering devices (so-called electric power steering devices) are increasing from the viewpoint of reducing engine load and weight. In this electric power steering device (hereinafter abbreviated as EPS), the motor as a driving source thereof is required to be downsized and high in performance because the device is arranged in a narrow bonnet space. Conventionally, DC motors with brushes have been widely used as such motors, but recently, with the improvement of control technology, the adoption of brushless motors that are superior in terms of miniaturization and high performance has increased. is doing.

  On the other hand, in the brushless motor, in order to rotationally drive the rotor, it is necessary to detect the rotational position of the rotor and sequentially excite the stator side coil (stator coil) based on the detected rotor rotational position. Conventionally, a detection device using an encoder, a Hall IC, or the like is used for detecting the rotational position of the rotor. In recent years, due to the demand for higher performance and lower noise of brushless motors, sensors with high resolution are also required for rotational position detection, and the use of resolvers, which are one of non-contact rotational sensors, is increasing. Resolvers are strong in high temperature and vibration environments, and have a simple structure and are not easily damaged. Therefore, the use of resolvers in in-vehicle motors, especially EPS, is increasing.

  When this resolver is used, it is required to detect the rotor rotational position with high accuracy. In order to improve the resolver accuracy, it is important that the motor unit and the magnetic circuit of the resolver are synchronized. And in order for both magnetic circuits to synchronize, the positional accuracy between a motor part and a resolver is important. For this reason, high accuracy is required for the positional relationship between the resolver rotor that determines the positional accuracy between the motor and the resolver and the rotor magnet of the motor portion. In particular, from the viewpoint of cost reduction, in a motor using a segment magnet for the rotor, it is necessary to first position the magnet with respect to the rotor core, and a magnet holder that also serves to fix the magnet is used.

  FIG. 7 is an explanatory diagram showing a schematic configuration of a rack shaft type EPS motor. As shown in FIG. 7, the magnet 101 is attached to a rotor core 103 that is press-fitted and fixed to the shaft 102. A magnet holder 104 is fixed to the rotor core 103. The magnet 101 is held and fixed to the outer peripheral surface of the rotor core 103 by a magnet holder 104. On the other hand, the resolver rotor 105 is usually fixed to the shaft 102. Spacers 106 and 107 are disposed on both sides of the resolver rotor 105 in the axial direction to prevent the resolver rotor 105 from coming off in the axial direction. Each spacer 106 and 107 is fixed to the shaft 102. The resolver rotor 105 is prevented from coming off in the axial direction by spacers 106 and 107.

  Positioning in the rotational direction of the resolver rotor is performed by providing a positioning index P on each of the shaft 102, the spacer 106, and the resolver rotor 105 and combining them. That is, first, the spacer 106 is press-fitted into the shaft 102 while aligning the indexes P with each other. Next, the spacer 106 and the index P of the resolver rotor 105 are aligned, and the resolver rotor 105 is bonded and fixed to the shaft 102. Further, a spacer 107 is press-fitted into the shaft 102, and the resolver rotor 105 is sandwiched between the spacers 106 and 107 to prevent axial removal.

In this case, the positioning index P provided on the shaft 102 indicates the reference position of the rotor. Therefore, with this index P as a reference, the rotor core 103 is fixed to the shaft 102 and the magnet holder 104 is fixed to the rotor core 103. Further, the positioning index P of the resolver rotor 105 also indicates a reference position as a single resolver. Accordingly, by attaching the magnet holder 104 and the resolver rotor 105 so as to match the index P, the magnet 101 held and fixed to the magnet holder 104 and the resolver rotor 105 are positioned and fixed in a predetermined angular positional relationship. Thereby, the motor circuit and the magnetic circuit of the resolver are synchronized, and the rotor rotational position using the resolver can be detected.
JP 2006-87277 JP Japanese Patent Laid-Open No. 2005-20887

  However, in the case of the motor configuration as described above, two spacers are required for attaching the resolver rotor. For this reason, there has been a problem that the number of parts increases, which causes an increase in cost. Further, in order to increase the positional accuracy between the motor portion and the resolver, high dimensional accuracy is required for each component. In particular, in the case of a configuration having a large number of parts, the assembly process is increased, and a high assembly accuracy is required each time.

  Further, when assembling each part, since the work is performed visually with reference to the positioning index, there is a problem that the assembling accuracy is lowered. In addition, there is also a problem that it hinders the improvement of mass productivity due to manual work by visual inspection. In particular, in the case of a configuration with a large number of parts, assembly errors accumulate, so it is difficult to improve the positional accuracy between the motor portion and the resolver, and the number of work steps increases. For this reason, there is a problem that it becomes an impediment to improving the rotor position detection accuracy and manufacturing cost, and the improvement has been demanded.

  An object of the present invention is to improve the positional accuracy between a motor portion and a resolver while reducing the number of parts around the resolver rotor in a brushless motor using a resolver.

  A brushless motor according to the present invention includes a stator including a stator core and a coil wound around the stator core, a rotor shaft disposed rotatably with respect to the stator, a rotor core fixed to the rotor shaft, and the rotor core A rotor having a magnet attached to the outer periphery of the rotor, a resolver rotor attached to the rotor shaft, a resolver having a resolver stator disposed outside the resolver rotor, and a magnet attached to the rotor. It has a magnet holder provided with the magnet holding | maintenance part hold | maintained and fixed to the outer periphery of the said rotor core, and the resolver rotor connection part connected with the said resolver rotor.

  In the present invention, a brushless motor having a stator, a rotor, and a resolver is provided with a magnet holder that holds and fixes a magnet and a resolver rotor connecting portion that is connected to the resolver rotor. The magnet and the resolver rotor can be mechanically connected with a predetermined angular positional relationship. For this reason, the positioning accuracy between the magnet and the resolver rotor is improved as compared with the method of aligning the index visually. Further, since no visual work is required, the assembly workability is improved, and the number of man-hours can be reduced accordingly.

  In the brushless motor, a resolver coupling portion that couples the resolver rotor connection portion and the resolver rotor may be provided between the resolver rotor connection portion and the resolver rotor. In this case, the resolver coupling portion may be provided with a resolver rotor connecting piece formed in the resolver rotor connecting portion and extending in the axial direction, and a fitting portion formed in the resolver rotor and into which the resolver rotor connecting piece is fitted. good. Further, the resolver rotor connecting piece and the magnet may be set to a predetermined angular positional relationship, and the fitting portion and the convex portion formed on the outer periphery of the resolver rotor may be set to a predetermined angular positional relationship. .

  In addition, a flange portion that abuts the resolver rotor on the rotor shaft and restricts movement of the resolver rotor in the axial direction may be provided. As a result, the resolver rotor is prevented from coming off by the flange portion, and it is not necessary to arrange a spacer on the rotor shaft, and accordingly, the number of parts and assembly man-hours are reduced.

  On the other hand, the resolver rotor connecting portion and the magnet holding portion may be provided so as to be separable. As a result, when the specification is changed, such as changing the energization timing, the change can be made only by changing the resolver rotor connecting portion without changing the magnet holding portion. This eliminates the need for a large and complex new mold, and allows flexible support for many vehicle body lineups with less expensive parts. In this case, a holder joint portion that joins the resolver rotor connection portion and the magnet holding portion may be provided between the resolver rotor connection portion and the magnet holding portion. Further, the holder joint may be provided with a fitting piece formed in the resolver rotor connecting portion and extending in the axial direction, and a fitting portion formed in the magnet holding and into which the fitting piece is fitted.

  According to the brushless motor of the present invention, in the brushless motor including the stator, the rotor, and the resolver, the magnet holder including the magnet holding portion that holds and fixes the magnet and the resolver rotor connecting portion that is connected to the resolver rotor is provided. Therefore, the magnet and the resolver rotor can be mechanically connected with a predetermined angular positional relationship, and the magnet and the resolver rotor can be positioned with high accuracy. Further, since the visual work is unnecessary, the assembling workability is improved, and the man-hour can be reduced correspondingly, and the manufacturing cost can be reduced.

  Also, by providing the rotor shaft with a flange portion that restricts the movement of the resolver rotor in the axial direction, the resolver rotor is prevented from coming off by the flange portion, and it is not necessary to arrange a spacer on the rotor shaft. It is possible to reduce the number of assembly steps. Further, since the dimensional accuracy of the portion where the spacer of the rotor shaft is fixed is relaxed, the manufacturing cost of the rotor shaft can be reduced.

  Furthermore, by providing the resolver rotor connection part and the magnet holding part in a separable manner, it is possible to respond to changes in specifications such as energization timing by changing the resolver rotor connection part without changing the magnet holding part. It becomes. For this reason, even when a mold is newly manufactured, only a magnet holding part is required, and it is not necessary to manufacture a large and complicated new mold. It becomes possible to respond.

It is sectional drawing which shows the structure of the brushless motor which is Example 1 of this invention. It is a perspective view of a magnet holder. (A) is sectional drawing of the magnet holder which followed the AA line of (b), (b) is a right view of a magnet holder. (A) is a side view of a resolver rotor, (b) is the sectional view. The structure of the magnet holding part of the brushless motor which is Example 2 of this invention is shown, (a) is the sectional drawing, (b) is a side view. The structure of the magnet holding part of the brushless motor which is Example 2 of this invention is shown, (a) is the front view, (b) is a left view, (c) is a right view. It is explanatory drawing which shows schematic structure of the rack shaft type EPS motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Rack shaft 3 Ball screw mechanism 11 Stator 12 Housing 13 Stator core 14 Coil 15 Insulator 15a Insulator 16 Terminal unit 17 Coil feed terminal 18 External connection terminal 19 Lead wire 21 Rotor 22 Rotor shaft 23 Rotor core 24 Magnet 25 Magnet cover 31 Housing 32 Bearing 33 Resolver 34 Resolver stator 35 Resolver rotor 36 Coil 41 Housing 42 Nut portion 43 Screw portion 44 Ball 45 Angular bearing 46a, 46b Bearing fixing ring 47 Step portion 48 Bearing fixing ring 49 Step portion 51 Magnet holder 52 Magnet holding Part 53 Rotor shaft fixing part 53a End face 54 Resolver rotor connection part 55 Part 56 Holder arm 57 Resolver rotor connecting piece 58 Base piece part 59 Fitting claw 61 Tapered part 62 Protruding part 63 Resolver coupling part 64 Flange part 65 Shaft insertion hole 66 Fitting groove (fitting part) 71 Brushless motor 72 Magnet holder 73 Magnet holding portion 74 Resolver rotor connecting portion 75 Holder joint portion 76 Base portion 77 Holder arm 78 Shaft insertion hole 79 Fitting groove 81 Fitting piece 101 Magnet
102 Shaft 103 Rotor core
104 Magnet holder 105 Resolver rotor
106 Spacer 107 Spacer P Positioning index

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a configuration of a brushless motor that is Embodiment 1 of the present invention. A motor 1 shown in FIG. 1 is used as a power source for a rack-assisted EPS, and has a configuration in which a rack shaft 2 penetrates the motor 1. The rotation of the motor 1 is transmitted to the rack shaft 2 via the ball screw mechanism 3 and becomes a steering assist force. The motor 1 has an inner rotor type device configuration in which a stator 11 is disposed outside and a rotor 21 is disposed inside. A resolver 33 is used to detect the rotational position of the rotor 21.

  The stator 11 includes a housing 12, a stator core 13 fixed to the inner peripheral side of the housing 12, and a coil 14 wound around the stator core 13. The housing 12 is made of iron or the like. A housing 41 made of aluminum die casting is attached to the left end side of the housing 12 in the drawing. The stator core 13 has a structure in which many steel plates are laminated. On the inner peripheral side of the stator core 13, a plurality of (here, nine) teeth are projected. A coil 14 is wound on a slot (nine slots) formed between the teeth via an insulator 15 made of synthetic resin.

  Insulators 15 are attached to both ends of the stator core 13. A terminal unit 16 is attached to the left end of the insulator 15 on the left side (insulator 15a) in FIG. The terminal unit 16 has a large number of coil feeding terminals 17 protruding in the radial direction. Each coil power supply terminal 17 is connected to a terminal portion of the coil 14 (a winding start portion or a winding end portion of the coil 14). The terminal unit 16 is further provided with an external connection terminal 18 electrically connected to the coil power supply terminal 17. A lead wire 19 is connected to the external connection terminal 18. Electric power is appropriately supplied to each coil 14 from a lead wire 19 connected to an external power supply via a terminal unit 16.

  The rotor 21 is disposed inside the stator 11. The rotor 21 has a configuration in which a cylindrical rotor shaft 22, a rotor core 23, a magnet 24, and a magnet cover 25 are arranged coaxially. The rack shaft 2 is inserted inside the rotor shaft 22. A cylindrical rotor core 23 is externally provided on the outer periphery of the rotor shaft 22. On the outer periphery of the rotor core 23, a magnet 24 having a 6-pole configuration is held and fixed by a magnet holder 51 made of synthetic resin. 2 is a perspective view of the magnet holder 51, FIG. 3A is a cross-sectional view of the magnet holder 51 along the line AA in FIG. 3B, and FIG. 2B is a right side view of the magnet holder 51.

  As shown in FIGS. 2 to 4, the magnet holder 51 includes a magnet holding part 52, a rotor shaft fixing part 53, and a resolver rotor connecting part 54. The magnet holding part 52 is provided with a base part 55 that is fixed to the rotor shaft 22 together with the rotor shaft fixing part 53, and a holder arm 56 that is formed to protrude from the base part 55 in the axial direction. The holder arm 56 has a cantilever structure extending in the axial direction from one end side of the base portion 55. The holder arm 56 has a substantially T-shaped cross section. Between the adjacent holder arms 56, the magnet 24 is press-fitted from the axial direction to the free end side (left end side in FIG. 3) of the holder arm 56. Thereby, the magnet 24 is held and fixed between the outer peripheral surface of the rotor core 23 and the holder arm 56. After the magnet 24 is mounted, the magnet cover 25 is externally attached to the outside of the magnet holder 51. As a result, the magnet 24 is pressed from the radial direction, and the movement of the magnet 24 in the axial direction is restricted (prevention from coming off).

  The rotor shaft fixing portion 53 is formed in a cylindrical shape and is formed integrally with the base portion 55. The inner diameter of the rotor shaft fixing portion 53 is formed slightly smaller than the outer diameter of the rotor shaft 22. The magnet holder 51 is press-fitted and fixed to the outer periphery of the rotor shaft 22 by the rotor shaft fixing portion 53.

  A resolver rotor connecting piece 57 connected to the resolver rotor 35 of the resolver 33 is provided at the end of the rotor shaft fixing portion 53 (the right end side in FIG. 1 and the upper end side in FIG. 2). The resolver rotor connecting pieces 57 are formed so as to protrude in the axial direction from the end of the rotor shaft fixing portion 53, and are formed in three equal portions in the circumferential direction. The resolver rotor connecting piece 57 has a predetermined angular positional relationship with the magnet 24 held and fixed to the magnet holding portion 52. The resolver rotor connecting piece 57 includes a base piece portion 58 projecting from the end surface 53 a of the rotor shaft fixing portion 53 and a fitting claw 59 projecting further in the axial direction from the base piece portion 58. The fitting claw 59 has a smaller circumferential dimension than the base piece portion 58. A tapered portion 61 is formed at the tip of the fitting claw 59.

  An aluminum die-cast housing 31 is attached to the right end side of the housing 12 in the figure. The housing 31 accommodates a bearing 32 that supports the right end side of the rotor 21 and a resolver 33 that detects the rotation of the rotor 21. The resolver 33 includes a resolver stator 34 fixed to the housing 31 side and a resolver rotor 35 fixed to the rotor 21 side. A coil 36 is wound around the resolver stator 34, and an excitation coil and a detection coil are provided.

  A resolver rotor 35 fixed to the rotor shaft 22 is disposed inside the resolver stator 34. 4A is a side view of the resolver rotor 35, and FIG. 4B is a sectional view thereof. As shown in FIG. 4B, the resolver rotor 35 has a configuration in which metal plates are laminated, and convex portions 62 are formed in three directions. When the rotor shaft 22 rotates, the resolver rotor 35 also rotates in the resolver stator 34. A high frequency signal is given to the exciting coil of the resolver stator 34, and the phase of the signal output from the detection coil changes due to the proximity of the convex portion 62. The rotational position of the rotor 21 is detected by comparing the detection signal with the reference signal. Then, based on the rotational position of the rotor 21, the current to the coil 14 is appropriately switched, and the rotor 21 is rotationally driven.

  Here, in the conventional brushless motor, as described above, the resolver rotor is attached by visual inspection, and spacers are arranged at the front and rear of the resolver rotor to prevent it from falling out. There was a problem. On the other hand, in the motor 1 according to the present invention, a resolver coupling portion 63 that couples both is provided between the magnet holder 51 and the resolver rotor 35 so that the resolver rotor 35 can be positioned with high accuracy. Yes. The rotor shaft 22 is formed with a flange portion 64 so that the resolver rotor 35 can be prevented from coming off without using a spacer.

  As shown in FIG. 4A, the resolver rotor 35 is formed with a shaft insertion hole 65 through which the rotor shaft 22 is inserted. In the shaft insertion hole 65, a fitting groove (fitting portion) 66 is notched along the axial direction. The fitting grooves 66 are arranged at three equal portions in the circumferential direction corresponding to the resolver rotor connecting pieces 57. The resolver rotor connecting piece 57 and the fitting groove 66 form a resolver coupling portion 63. The fitting groove 66 is formed so as to have a predetermined angular positional relationship with the convex portion 62 of the resolver rotor 35. The dimension of the fitting groove 66 in the circumferential direction is slightly smaller than the dimension of the fitting claw 59 in the circumferential direction, and the fitting claw 59 is attached so as to be lightly press-fitted into the fitting groove 66.

  On the other hand, a flange portion 64 is formed near the right end of the rotor shaft 22 as shown in FIG. The flange portion 64 is formed with a larger diameter than other portions of the rotor shaft 22. When the resolver rotor 35 is attached to the rotor shaft 22, one end side of the resolver rotor 35 comes into contact with the flange portion 64. Thereby, the movement of the resolver rotor 35 in the axial direction is restricted, and the resolver rotor 35 is prevented from coming off in the axial direction on the rotor shaft 22.

  In the motor 1 having such a configuration, the resolver rotor 35 is first attached to the rotor shaft 22. The resolver rotor 35 is attached by inserting the rotor shaft 22 into the shaft insertion hole 65 and press-fitting the resolver rotor 35 into the rotor shaft 22. The resolver rotor 35 is press-fitted to a position where it comes into contact with the flange portion 64. Thereafter, the magnet holder 51 is press-fitted and fixed to the rotor shaft 22. At this time, the fitting claw 59 of the resolver rotor connecting piece 57 is lightly press-fitted into the fitting groove 66 of the resolver rotor 35.

  The fitting claw 59 has a predetermined angular positional relationship with the magnet 24 held and fixed to the magnet holder 51. The fitting groove 66 has a predetermined angular position relationship with the convex portion 62 of the resolver rotor 35. Therefore, by attaching the fitting claw 59 to the fitting groove 66, the magnet 24 and the resolver rotor 35 are connected in a predetermined angular positional relationship. That is, the positional relationship between the magnet 24 and the resolver rotor 35 is mechanically set by the fitting claw 59 and the fitting groove 66. For this reason, in the motor 1, the positioning accuracy can be dramatically improved as compared with the method in which the index is visually adjusted. Further, since no visual work is required, the assembly workability is improved, and the man-hours can be reduced accordingly.

  Further, since the positioning of the magnet 24 and the resolver rotor 35 in the circumferential direction is performed with high accuracy, the adjustment angle of the resolver stator 34 at the time of final position adjustment of the resolver 33 is reduced, and the adjustment work of the resolver 33 is easy. It becomes. In addition, the long hole provided for adjusting the resolver can be made small, and the dimensions of the bracket for forming the long hole can be reduced. Since the bracket for forming the long hole is in a position where it can easily interfere with other parts / parts in the motor, it is preferable that this portion be as small as possible. Therefore, if the circumferential dimension of the long hole is reduced and the bracket is made smaller, a space is generated in the circumferential direction, thereby improving the layout in the motor and reducing the size of the motor as a whole. It becomes possible.

  The resolver rotor 35 is mounted on the rotor shaft 22 so as to be sandwiched between the flange portion 64 and the base piece portion 58 of the resolver rotor connecting piece 57. Therefore, the motor 1 can prevent the resolver rotor 35 from coming off in the axial direction without using a special spacer. For this reason, compared with the conventional brushless motor, since the number of parts can be reduced and the spacer assembling work is not required, the productivity can be improved and the cost can be reduced. Furthermore, since the dimensional accuracy of the portion where the spacer of the rotor shaft 22 is fixed is relaxed, the cost can be reduced accordingly.

  In addition, the weight and inertia of the spacer can be reduced, the motor can be reduced in weight, and the control response can be improved. For this reason, the commercial value as an EPS motor is also improved. Further, by eliminating the retaining by the spacer, the resolver rotor 35, the magnet holder 51, the rotor core 23, and the like can be assembled to the rotor shaft 22 from the same direction, and the workability can be improved also in this respect. In addition, since the outer dimensional accuracy of the flange portion 64 may be relatively rough, the cost reduction due to the dimensional accuracy relaxation of the spacer fixing portion is greater than the cost increase associated with the formation of the flange portion 64.

  A housing 41 is attached to the left end side of the housing 12. A ball screw mechanism 3 is incorporated in the housing 41. The ball screw mechanism 3 includes a nut portion 42, a screw portion 43 formed on the outer periphery of the rack shaft 2, and a large number of balls 44 interposed between the nut portion 42 and the screw portion 43. . The rack shaft 2 is supported so as to be reciprocable in the left-right direction by the nut portion 42 in a state where the rotation around the shaft is restricted, and moves in the left-right direction as the nut portion 42 rotates.

  The nut portion 42 is fixed to the left end portion of the rotor shaft 22 and is rotatably held by an angular bearing 45 fixed to the housing 41. The angular bearing 45 is in a state in which the axial movement is restricted between the bearing fixing rings 46 a and 46 b screwed into the opening of the housing 41 and the stepped portion 47 formed inside the housing 41. It is fixed. Further, the axial movement between the nut portion 42 and the angular bearing 45 is caused by a bearing fixing ring 48 screwed into the left end of the nut portion 42 and a step portion 49 formed on the outer periphery of the nut portion 42. Be regulated.

  In an EPS equipped with such a motor 1, the steering handle is first operated to rotate the steering shaft, and the rack shaft 2 is moved in a direction corresponding to the rotation to perform a steering operation. When a steering torque sensor (not shown) is activated by this operation, electric power is supplied from the battery to the coil 14 via the lead wire according to the detected torque. When electric power is supplied to the coil 14, the motor 1 operates and the rotor shaft 22 rotates. When the rotor shaft 22 rotates, the nut portion 42 coupled therewith rotates, and the steering assist force in the axial direction is transmitted to the rack shaft 2 by the action of the ball screw mechanism 3. Thereby, the movement of the rack shaft 2 is promoted, and the steering force is assisted.

  Next, a brushless motor that is Embodiment 2 of the present invention will be described. The brushless motor 71 of the second embodiment (hereinafter abbreviated as “motor 71”) has the same basic configuration as the motor 1 of the first embodiment, but the magnet holder 72 has a divided structure, which improves the degree of freedom in design. It is illustrated. In the second embodiment, the same members and portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Here, in the brushless motor for EPS, a highly flexible product that can cope with a wide variety of vehicle body lineups is required. However, brushless motors are still more expensive than brushed motors, and how to manufacture motors with a wide variety of specifications, including single-part machining methods, is a major issue. For example, regarding the energization timing of the motor, it is necessary to appropriately change the setting according to various specifications. In particular, regarding EPS motors, the specifications of the vehicle body (left and right of the handle, etc.) are diversified, so in order to share parts as much as possible, various specifications are often handled by changing energization timing.

  Such a change in the energization timing can be arbitrarily made by design according to the configuration on the stator side or the rotor side, and the following changing method is known. First, as a method of changing the energization timing on the stator side, there is a method of changing the angular positional relationship in the circumferential direction between the resolver stator and the stator core. In this case, to change the positional relationship, there are a method of changing the angular position of the resolver stator and a method of changing the angular position of the stator core. In the former case, since the resolver stator is integrated with a connector for connecting the sensor wire, it is necessary to change the structure of the resolver stator in order not to change the drawing position of the sensor connector.

  On the other hand, in the latter case, since the stator core is integrated with the external connection terminal (power connector) via the terminal unit, it is necessary to change the structure of the terminal unit in order not to change the drawing position of the external connection terminal. There is. That is, when the energization timing is changed on the stator side, the resolver stator or the terminal unit must be changed greatly.

  Next, as a method of changing the energization timing on the rotor side, there is a method of changing the circumferential angular positional relationship between the rotor magnet and the resolver rotor. In this case, in the motor 1 of the first embodiment, the angular position relationship between the magnet 24 and the resolver rotor 35 is easily changed by changing the position of the resolver rotor connecting piece 57 formed in the magnet holder 51 in the circumferential direction. be able to. Therefore, when the change on the stator side is compared with the change on the rotor side, the specification on the rotor side can be changed more easily.

  However, in order to change the setting on the rotor side, it is necessary to change the position of the resolver rotor connecting piece 57, and when changing the setting, it is necessary to design the dedicated magnet holder 51 individually. For this reason, regarding the magnet holder 51, a new metal mold must be produced each time according to the specifications. However, the mold of the magnet holder 51 is relatively large, and the shape of the part for holding and fixing the magnet 24 is complicated, so that the mold structure is also complicated. Therefore, there is a problem that the cost required for mold production is increased, the magnet holder is not an inexpensive part, and a considerable increase in cost is unavoidable due to a change in energization timing.

  Therefore, in the brushless motor 71 according to the second embodiment of the present invention, the magnet holder 72 is divided into two in the axial direction, and the magnet holder is shared, thereby realizing a reduction in mold cost. That is, in the brushless motor 71, the magnet holder 72 is composed of two parts, that is, a magnet holding part 73 and a resolver rotor connecting part 74, and both are integrally joined by a holder joining part 75. FIG. 5 shows the configuration of the magnet holding portion 73, and FIG. 6 shows the configuration of the resolver rotor connecting portion 74. As shown in FIG. 5, the magnet holding portion 73 has a configuration in which the lower half of the magnet holder 51 of FIG. 2 is made independent, and a base portion 76 and a holder arm 77 are formed.

  Similarly to the magnet holder 51, the holder arm 77 extends from the base portion 76 in the axial direction. The cross section of the holder arm 77 is substantially T-shaped. A magnet 24 is press-fitted between the adjacent holder arms 77 from the axial direction. Thereby, the magnet 24 is held and fixed between the outer peripheral surface of the rotor core 23 and the holder arm 77. The base portion 76 is formed in a ring shape. A shaft insertion hole 78 through which the rotor shaft 22 is inserted is formed in the base portion 76. A fitting groove 79 is formed around the shaft insertion hole 78 along the axial direction. The fitting groove 79 is equally divided into three places in the circumferential direction.

  On the other hand, a resolver rotor connecting piece 57 is provided on the right end side of the resolver rotor connecting portion 74 in FIG. The resolver rotor connecting pieces 57 are provided so as to protrude in the axial direction from the end of the resolver rotor connecting portion 74, and three resolver rotor connecting pieces 57 are formed equally in the circumferential direction. As described above, the resolver rotor connecting piece 57 includes a base piece portion 58 and a fitting claw 59 and is lightly press-fitted into the fitting groove 66 of the resolver rotor 35. Further, a fitting piece 81 used for connection to the magnet holding portion 73 is also provided on the left end side of the resolver rotor connecting portion 74 so as to project. The fitting pieces 81 are arranged at three equal portions in the circumferential direction corresponding to the fitting grooves 79 of the magnet holding portion 73. A holder joint 75 is formed by the fitting groove 79 and the fitting piece 81. The circumferential dimension of the fitting piece 81 is slightly larger than the circumferential dimension of the fitting groove 79. The resolver rotor connecting portion 74 is attached to the magnet holding portion 73 in such a manner that the fitting piece 81 is lightly press-fitted into the fitting groove 79.

  In such a magnet holder 72, when the circumferential position of the fitting piece 81 is changed, the circumferential positional relationship between the magnet 24 and the resolver rotor connecting piece 57 is changed. That is, the angular positional relationship between the magnet 24 and the resolver rotor 35 can be appropriately changed by setting the position of the fitting piece 81. In this case, in the magnet holder 51 as shown in FIG. 2, as described above, it is necessary to change the design of the entire magnet holder 51, and therefore, it is necessary to newly create a large and complicated mold. On the other hand, in the motor 71 of the second embodiment, in order to change the angular positional relationship between the magnet 24 and the resolver rotor 35, it is only necessary to change the design of the resolver rotor connecting portion 74, and the complicated-shaped magnet holding portion 73 remains as it is. Can be shared.

  That is, in the motor 71, the energization timing can be changed by simply adjusting the angle of the position of the resolver rotor connecting piece 57 in the resolver rotor connecting portion 74 in the circumferential direction without changing the shape of the magnet holding portion 73. . Therefore, it is possible to respond to a wide variety of specifications only by changing the resolver rotor connecting portion 74, eliminating the need for a large and complex new mold when changing the specifications, and flexibly responding to many vehicle body lineups with cheaper parts It becomes possible. Further, the resolver rotor connecting portion 74 for newly producing a mold can also be molded with a simple mold divided into upper and lower parts because of a simple shape without an undercut portion. Therefore, according to the motor of the present invention, it is possible to provide a product with excellent cost performance with reduced mold costs.

  Furthermore, since the resolver rotor connecting portion 74 can be manufactured by cutting without producing a mold, it is possible to shorten the lead time for producing a prototype when considering a small production such as a prototype. . In addition, there are specifications for brushless motors with different magnetic circuit lengths. However, if the magnet holder with a short magnetic circuit length can sufficiently hold the magnet of a long motor, the short magnet holder can be used. It is enough to make only. Therefore, the part specifications can be reduced correspondingly, and the cost can be further reduced.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, the resolver rotor connection piece 57 and the fitting groove 66 form the resolver coupling portion 63, and the fitting groove 79 and the fitting piece 81 form the holder joint portion 75. It is possible to appropriately change which side of the coupling portion 63 and the joint portion 75 is to be provided with the unevenness. For example, in the resolver coupling portion 63, a pin may be implanted on the resolver rotor 35 side, and a notch, a hole, a groove, or the like into which the pin can be fitted may be provided in the magnet holder 51. Moreover, you may set the uneven | corrugated relationship in the holder junction part 75 reversely.

  Furthermore, in the above-described embodiment, the configuration in which the two spacers on both sides of the resolver rotor are eliminated is shown. However, the spacers may be arranged only on the right side of the resolver rotor 35 in FIG. good. In addition, although the magnet holders 51 and 71 are fixed to the rotor shaft 22, the magnet holders 51 and 71 may be fixed to the rotor core 23.

  On the other hand, in the above-described embodiment, an example in which the stator according to the present invention is used for a brushless motor used as an EPS drive source has been described. However, the stator is not limited to an EPS brushless motor, and is used for other applications. Widely applicable to motors. Further, the present invention can be widely applied to general brushless motors as well as motors for EPS and various in-vehicle electric products. Furthermore, in the above-described embodiment, the brushless motor used for the rack assist type EPS is shown, but the present invention can also be applied to other types of EPS motors such as a column assist type.

Claims (8)

A stator comprising a stator core and a coil wound around the stator core;
A rotor that is rotatably arranged with respect to the stator, and includes a rotor shaft, a rotor core fixed to the rotor shaft, and a magnet attached to an outer periphery of the rotor core;
A resolver comprising: a resolver rotor attached to the rotor shaft; and a resolver stator disposed outside the resolver rotor;
A brushless motor, comprising: a magnet holding part that is attached to the rotor and holds and fixes the magnet on an outer periphery of the rotor core; and a magnet holder including a resolver rotor connection part connected to the resolver rotor. .   The brushless motor according to claim 1, wherein a resolver coupling portion that couples the resolver rotor connection portion and the resolver rotor is provided between the resolver rotor connection portion and the resolver rotor.   3. The brushless motor according to claim 2, wherein the resolver coupling part is a fitting in which the resolver rotor connecting piece is formed in the resolver rotor connecting part and extends in the axial direction, and the resolver rotor connecting piece is formed in the resolver rotor. And a brushless motor.   4. The brushless motor according to claim 3, wherein the resolver rotor connecting piece has a predetermined angular positional relationship with respect to the magnet, and the fitting portion has a predetermined angular positional relationship with a convex portion formed on an outer periphery of the resolver rotor. A brushless motor characterized by comprising:   2. The brushless motor according to claim 1, wherein the rotor shaft has a flange portion that abuts the resolver rotor and restricts movement of the resolver rotor in an axial direction.   2. The brushless motor according to claim 1, wherein the resolver rotor connecting portion and the magnet holding portion are separable.   7. The brushless motor according to claim 6, wherein a holder joint for joining the resolver rotor connecting portion and the magnet holding portion is provided between the resolver rotor connecting portion and the magnet holding portion. .   8. The brushless motor according to claim 7, wherein the holder joint portion includes a fitting piece formed in the resolver rotor connection portion and extending in an axial direction, and a fitting portion formed in the magnet holding and into which the fitting piece is fitted. A brushless motor characterized by comprising:

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