JP6519676B2 - Vehicle brushless motor - Google Patents

Description

  The present invention relates to a brushless motor for a vehicle.

2. Description of the Related Art In recent years, an electric power steering system (EPS) that assists a steering operation by using an electric motor as a driving force is being adopted as a steering system for vehicles.
As a motor used in this system, a so-called SPM (Surface Permanent Magnet) type motor is proposed in which permanent magnets having different magnetic pole directions in the radial direction are alternately stuck in the circumferential direction on the outer peripheral surface of the rotor ( For example, Patent Document 1). Also, as a motor used in the system, a so-called IPM (Interior Permanent Magnet) type motor has been proposed in which permanent magnets having different magnetic pole directions in the radial direction are alternately embedded in the circumferential direction in the rotor (for example, , Patent Document 2).

JP 2007-318998 A Unexamined-Japanese-Patent No. 2000-236652

  By the way, in this type of electric power steering system, maintaining a high output, low cogging torque and low torque ripple under a wide temperature environment of -40 ° C to 100 ° C or more to obtain a good steering feel It is required.

  In general, it is known that permanent magnets become weaker in magnetic force as they get higher temperature, and become stronger as they get lower temperature. Therefore, for example, when the magnetic flux is reduced in the high temperature region, control to increase the motor current or control to advance the phase (field weakening) is performed. At this time, the permanent magnet acts in the direction to decrease the magnetic flux, there is a possibility that irreversible demagnetization may occur, and there is a problem of changing the characteristics of the permanent magnet and, consequently, changing the motor characteristics.

  In particular, in neodymium magnets, SmFeN magnets (samarium iron nitride magnets), SmCo magnets (samarium cobalt magnets), etc., it is easy to demagnetize in a high temperature region, so when using these permanent magnets in a motor, temperature measures are required. . In addition, since ferrite magnets are easily demagnetized in a low temperature region, temperature countermeasures are also required when using ferrite magnets in a motor.

  In addition, the electric steering system tends to be equipped with various electrical components around it. Therefore, the mounting space of the motor used for the electric power steering system is reduced, and further downsizing is required while maintaining the output.

  The present invention has been made to solve the above problems, and its object is to make it difficult to change the characteristics of a permanent magnet provided on a rotor even in a small size and a wide temperature environment, and to reduce torque pulsation and increase torque. It is an object of the present invention to provide a vehicle brushless motor that is compatible with the above.

A vehicle brushless motor that solves the above problems includes a motor case, a stator disposed in the motor case and wound by a winding, a rotor disposed inside the stator, and the motor fixed to the rotor. It is a brushless motor for vehicles provided with the rotating shaft which consists of a nonmagnetic material and drivingly connected with a reduction gear in the portion which protrudes from a case, and, as for the rotor, a plurality of 1st projected pieces are formed in the circumferential direction at equal intervals. A plurality of second protrusions are formed at equal intervals in the circumferential direction and have the same shape as the first rotor core and the first rotor core, and the second protrusions are the first protrusions of the first rotor core in the axial direction. A second rotor core disposed relative to the first rotor core so as to be located between the piece and the first projection, and disposed between the first rotor core and the second rotor core and axially magnetized And a field member for generating a first magnetic pole on a first projecting piece of the first rotor core and a second magnetic pole on a second projecting piece of the second rotor core, and the first rotor core has a rotating shaft A disc-shaped first core base fixed to the first core base, and a first projecting piece is formed on the first core base in a radial direction from an outer peripheral surface, and the second rotor core is mounted on the rotation shaft It has a disk-shaped second core base fixed, and a second projecting piece is formed on the second core base in the radial direction from the outer peripheral surface, from the direction orthogonal to the axial direction of the rotation axis The gear of the reduction gear is provided coaxially with the rotor in the motor case at a portion of the rotation shaft projecting from the motor case, and the field member has an outer diameter of the The same as the outer diameter of the first and second core bases and outside the gear A thin disk-shaped permanent magnet than the thickness of the axial direction of the first and second core base in the axial direction thickness with greater than, the first protrusion formed in the first core base diameter Protruding outward in the axial direction and having its tip bent to extend toward the second rotor core in the axial direction, and the second projection formed on the second core base protrudes radially outward and has its tip bent to form an axial line The direction is extended toward the first rotor core side.

  According to the configuration, the field member is shielded from external temperature changes by the first and second rotor cores to improve heat resistance, and demagnetization due to the rotating magnetic field can be made difficult to occur under a wide range of external temperature environments. In addition, since the field member is disposed between the first rotor core and the second rotor core and axially held, the size of the motor can be reduced and scattering of the field member due to centrifugal force is prevented. it can.

  Also, the field member is disposed between the first core base and the second core base. Then, a first magnetic pole is generated on a first protrusion formed to extend from the first core base of the first rotor core by the field member, and a second protrusion is formed to extend from the second core base of the second rotor core. A second magnetic pole is generated on one of the pieces.

  Further, the first projecting piece generated by the first magnetic pole is projected radially outward from the outer peripheral surface of the first core base, and the tip is bent to extend toward the second rotor core in the axial direction. Further, the second projecting piece generated by the second magnetic pole is projected radially outward from the outer peripheral surface of the second core base, and the tip is bent to extend toward the first rotor core in the axial direction.

In the above-described vehicle brushless motor, windings wound around the brushless motor stator are supplied with three-phase drive current.
In the above-described vehicle brushless motor, a circumferentially magnetized interpolar magnet is provided between the first protrusion and the second protrusion in the circumferential direction, and a radially inner side of the first protrusion is provided. A radially magnetized back magnet is provided radially inward of the second protrusion.

  In the above-described vehicle brushless motor, it is possible to make it difficult to change the characteristics of the permanent magnet provided on the rotor even under a small and wide temperature environment, and it is possible to achieve both low torque pulsation and high torque.

Explanatory drawing for demonstrating the electric-power-steering system of 1st Embodiment. Sectional drawing of the axial direction for demonstrating a three phase brushless motor. The whole perspective view for similarly explaining a stator and a rotor. Similarly, a radial sectional view of the stator and the rotor. The whole perspective view for similarly explaining a rotor. The disassembled perspective view for demonstrating a rotor similarly. Sectional drawing of the axial direction for demonstrating the brushless motor of 2nd Embodiment. The radial sectional view for similarly explaining a brushless motor. Similarly, an axial sectional view of the stator and the rotor. The whole perspective view for similarly explaining a rotor. The disassembled perspective view for demonstrating a rotor similarly. The whole perspective view for demonstrating the rotor of the brushless motor of 3rd Embodiment. Similarly, an axial sectional view of the rotor. The whole perspective view seen from the 1st rotor core side of the rotor of a 4th embodiment. Similarly, the whole perspective view seen from the 2nd rotor core side of a rotor. Similarly, an axial sectional view of the rotor.

First Embodiment
Hereinafter, a first embodiment of a motor for an electric power steering system according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the electric power steering system 1 is a column assist type, and has a steering shaft 3 having a steering wheel 2 fixed at its base end, and the distal end of the steering shaft 3 has a universal joint 4. It is linked to Intermediate 5 via: The steering shaft 3 includes an input shaft 3a and an output shaft 3b, and a part of the output shaft 3b is inserted into the cylindrical input shaft 3a. The steering wheel 2 is fixed to the base end of the input shaft 3a, and the universal joint 4 is connected to the tip of the output shaft 3b. In addition, a torsion bar (not shown) is provided between the input shaft 3a and the output shaft 3b so as to rotate the output shaft 3b following the rotation of the input shaft 3a.

  Then, the rotation and steering torque based on the steering operation is transmitted to the rack 7 and the pinion shaft 8, and the rotation of the pinion shaft 8 causes the rack 7 to reciprocate in the vehicle width direction. As a result, the steering angle of the steered wheels 10 is changed via the tie rods 9 connected to both ends of the rack 7.

  A steering column 11 is mounted on the input shaft 3 a of the steering shaft 3. The steering column 11 is provided with a three-phase brushless motor (hereinafter referred to as a brushless motor) M as a motor for an electric power steering system. The brushless motor M applies an auxiliary steering force (hereinafter referred to as an assist torque) to the steering wheel 2 when the steering operation is performed by controlling the rotation of the input shaft 3a.

  More specifically, when the input shaft 3a is rotated based on the operation of the steering wheel 2, a displacement occurs with the output shaft 3b, and this displacement appears as a torsion of the torsion bar. That is, the output shaft 3b is delayed with respect to the rotation of the input shaft 3a due to the road surface resistance of the steering wheel 10 or the like, and the torsion bar is twisted.

  Then, the torsion angle of the torsion bar is detected by a torque sensor (not shown), the steering torque applied to the input shaft 3a (steering wheel 2) is detected, and the assist at the steering operation is performed based on the detected steering torque. The torque is calculated, and drive control of the brushless motor M is performed.

  As shown in FIG. 2, the motor case 20 of the brushless motor M has a bottomed cylindrical motor housing 20a having an outer diameter of 10 cm, and a front cover 20b for closing an opening on the front side of the motor housing 20a. have.

  A stator 21 is fixed to the inner peripheral surface of the motor housing 20a, and a rotor 25 is fixed to the inner side of the stator 21 and fixed to a rotating shaft 22 made of nonmagnetic material (for example, stainless steel). It is set up. The rotation shaft 22 is rotatably supported by bearings 23, 24 provided on the bottom of the motor housing 20a and the front cover 20b, and a reduction gear whose tip protruding from the front cover 20b is formed of gears 26, 27 and the like. It is drivingly connected to the input shaft 3a of the steering shaft 3 via 28.

(Stator 21)
As shown in FIG. 3, the stator 21 has a cylindrical stator core 30, and the outer peripheral surface of the stator core 30 is fixed to the motor housing 20 a. Inside the stator core 30, a plurality of teeth 31 formed along the axial direction and arranged at equal intervals in the circumferential direction are formed to extend radially inward. The teeth 31 are such that circumferentially opposite side surfaces of the tip end portion project in the circumferential direction, and the radially inner end surface is an arc surface centered on the central axis L1 (see FIG. 4) of the rotating shaft 22. It is a T-shaped tooth formed.

  The stator side slot 32 is formed between the teeth 31 and the teeth 31. In the present embodiment, the number of teeth 31 is twelve, and the number of stator side slots 32 is twelve, which is the same as the number of teeth 31.

Then, on each tooth 31, three-phase windings, that is, U-phase winding 33a, V-phase winding 33b, and W-phase winding 33c are wound in a concentrated winding order in the clockwise direction.
(Rotor 25)
As shown in FIG. 3, a rotor 25 fixed to the rotating shaft 22 is disposed inside the stator 21. As shown in FIGS. 5 and 6, the rotor 25 includes a first rotor core 40, a second rotor core 50 disposed opposite to the first rotor core 40, a first rotor core 40, and a second rotor core 50. A disc magnet (field member) 55 is disposed between the two.

(First rotor core 40)
The first rotor core 40 is formed of a magnetic steel sheet in the present embodiment, and has a first core base 41 as shown in FIGS. 5 and 6. At a central position of the first core base 41, a through hole 42 for penetrating and fixing the rotary shaft 22 is formed. Further, seven first protrusions 43 are formed on the outer peripheral surface of the first core base 41 so as to extend in the radial direction at equal pitches. The outer peripheral surface of each first projecting piece 43 is formed to be an arc surface centering on the central axis L1 of the rotation shaft 22.

  Further, the width of each first protrusion 43 in the circumferential direction is formed to be smaller than the distance between the first protrusion 43 and the first protrusion 43. As a result, on the first rotor core 40, the first projecting pieces 43 with an equal pitch are formed to extend in the circumferential direction.

(Second rotor core 50)
The second rotor core 50 is formed of an electromagnetic steel plate in the present embodiment, has the same shape as the first rotor core 40, and has a second core base 51 as shown in FIGS. 5 and 6. At a central position of the second core base 51, a through hole 52 for penetrating and fixing the rotary shaft 22 is formed. Further, seven second protrusions 53 are formed on the outer peripheral surface of the second core base 51 so as to extend in the radial direction at equal pitches. The outer peripheral surface of each of the second protrusions 53 is formed to be an arc surface centered on the central axis L1 of the rotation shaft 22.

  Further, the width in the circumferential direction of each second protrusion 53 is formed to be smaller than the distance between the second protrusion 53 and the second protrusion 53. As a result, second protrusions 53 having an equal pitch in the circumferential direction are formed on the second rotor core 50 so as to extend therefrom.

  The second rotor core 50 has a first projection 43 and a first projection 43 in which the second projection 53 does not face the first projection 43 of the first rotor core 40 when viewed from the axial direction with respect to the first rotor core 40. It is arranged and fixed to the rotating shaft 22 so as to be located between the projecting pieces 43. When the first rotor core 40 and the second rotor core 50 are arranged and fixed to the rotary shaft 22, as shown in FIGS. 4 and 5, the disc magnet 55 is assembled between the first rotor core 40 and the second rotor core 50. .

(Disc magnet 55)
In the present embodiment, the disc magnet 55 is a disc-shaped permanent magnet made of a neodymium magnet. As shown in FIG. 6, the disc magnet 55 is formed with a through hole 56 penetrating the rotation shaft 22 at the center position thereof. The one side surface 55 a of the disc magnet 55 is the surface of the first core base 41 on the second rotor core 50 side (facing surface 41 a), and the other side surface 55 b of the disc magnet 55 is the second core base 51. The disc magnet 55 is held between the first rotor core 40 and the second rotor core 50 so as to be held in contact with the surface (facing surface 51 a) on the first rotor core 40 side.

  The outer diameter of the disk magnet 55 is made to coincide with the outer diameter of the first and second core bases 41 and 51 of the first and second rotor cores 40 and 50. In other words, the outer diameter of the disk magnet 55 is formed shorter than the outer diameter of the first and second rotor cores 40 and 50 (the first and second projecting pieces 43 and 53).

  The thickness of the disc magnet 55 is also set to a predetermined thickness thinner than the thickness of the first core base 41 (second core base 51). Incidentally, when the disc magnet 55 is assembled between the pair of first rotor core 40 and the second rotor core 50 to form the rotor 25, the axial length of the rotor 25 is one outer diameter of the rotor 25. It is set to have a length of 2 or less.

  As shown in FIG. 4, the disc magnet 55 is magnetized in the axial direction, and is magnetized so that the first rotor core 40 side is an N pole and the second rotor core 50 side is an S pole. Therefore, by the disc magnet 55, the first projecting piece 43 of the first rotor core 40 functions as an N pole (first magnetic pole), and the second projecting piece 53 of the second rotor core 50 as an S pole (second magnetic pole) Function.

  As a result, the rotor 25 of the present embodiment becomes a magnet field rotor using the disc magnet 55. In the rotor 25 according to this embodiment, the first projecting piece 43 serving as the N pole and the second projecting piece 53 serving as the S pole are alternately disposed in the circumferential direction, and the number of magnetic poles is 14 (the number of pole pairs is 7). ) Rotors. That is, in the rotor 25 of the present embodiment, the number of pole pairs is an odd number of 3 or more.

Next, the operation of the brushless motor M configured as described above will be described.
In the rotor 25 of the brushless motor M according to the present embodiment, the disc magnet 55 is provided between the first rotor core 40 and the second rotor core 50. The disc magnet 55 generates an N pole (first magnetic pole) on the first projecting piece 43 of the first rotor core 40 and an S pole (second magnetic pole) on the second projecting piece 53 of the second rotor core 50. As a result, the rotor 25 of the magnet field is made. Thus, the axial length of the rotor 25 can be shortened, and the size of the brushless motor M can be reduced. In addition, since the axial length of the rotor 25 is set to a half or less of the outer diameter of the rotor 25, the brushless motor M has a smaller axial size.

  The rotor 25 is rotated by energizing the U-phase winding 33a, the V-phase winding 33b, and the W-phase winding 33c wound around the teeth 31 around the stator 21 to create a rotating magnetic field. The rotation of the rotor 25 drives the input shaft 3 a of the steering shaft 3 via the rotation shaft 22 and the reduction gear 28 to apply an assist torque to the steering wheel 2.

  Further, when the brushless motor M is driven to rotate, the brushless motor M (the rotor 25) rotates at a high speed of 2000 rpm or more in order to drive a large load via the reduction gear 28. At this time, the disc magnet 55 is disposed between the first rotor core 40 and the second rotor core 50, and is axially moved by the first and second rotor cores 40, 50 (the first and second core bases 41, 51). Because it is held, it does not scatter due to centrifugal force.

  Further, both side surfaces 55a, 55b of the disc magnet 55 are in pressure contact with the facing surfaces 41a, 51a of the first and second core bases 41, 51 of the first and second rotor cores 40, 50 made of electromagnetic steel plates. Therefore, even if the outside air temperature is in a high temperature range of 100 ° C. or higher, the external temperature change of the disc magnet 55 is blocked by the first and second rotor cores 40 and 50, and the heat resistance is improved. In particular, in the case of the disc magnet 55 made of a neodymium magnet having irreversible demagnetization in a high temperature region, the structure is excellent in heat resistance. Thereby, in a wide range of external temperature environment, the change of the magnetic characteristic of the disc magnet 55 is less likely to occur due to the rotating magnetic field generated from the energization of the U-phase winding 33a, V-phase winding 33b, W-phase winding 33c. it can.

As a result, high power, low cogging torque and low torque ripple can be maintained under all operating temperatures to obtain a good steering feel.
Further, since the rotor 25 has an odd number of pole pairs of 7, when viewed on a rotor core basis, the magnetic poles of the same pole do not face each other in the circumferential direction 180 °, so that the rotor 25 has a shape stable against magnetic vibration. The low cogging torque and the low torque ripple can be improved to obtain a good steering feel.

Next, the effects of the first embodiment will be described below.
(1) According to the present embodiment, the disk magnet 55 is shielded from external temperature changes by the first and second rotor cores 40 and 50 to improve heat resistance, and in a wide external temperature environment, the disk by the rotating magnetic field Changes in the magnetic properties of the magnet 55 can be made less likely to occur.

  (2) According to the present embodiment, since the disc magnet 55 is disposed between the first rotor core 40 and the second rotor core 50 and axially held, the disc magnet 55 is centrifugally It can prevent scattering.

  (3) According to the present embodiment, the rotor 25 is a magnet field rotor in which the disc magnet 55 is sandwiched between the two rotor cores 40 and 50, and the physical size of the brushless motor M can be reduced. In addition, since the axial length of the rotor 25 is set to a half or less of the outer diameter of the rotor 25, the brushless motor M can make the physical size in the axial direction smaller.

  (4) According to the present embodiment, since the number of pole pairs of the rotor 25 is an odd number 7, the shape is stabilized against magnetic vibration, and the low cogging torque and the low torque ripple are improved to obtain a good steering feel. be able to.

  (5) According to this embodiment, the reluctance torque can be used by the first and second projecting pieces 43 and 53, and the brake torque generated at the time of failure can be suppressed to a low level, and the steering becomes lighter by that amount. Steering operation becomes easy.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is different from the first embodiment in the configuration of the brushless motor M. Therefore, only the different brushless motor M will be described in detail, and common parts will be omitted for convenience of explanation.

FIG. 7 shows a cross-sectional view of the brushless motor M of the present embodiment, and the stator 21 is fixed to the inside of the motor housing 20a.
As shown in FIG. 8, 60 teeth 31 are formed to extend radially inward on the stator core 30 of the stator 21. Therefore, 60 stator side slots 32 formed between the teeth 31 are formed, and the 60 stator side slots 32 are formed at equal angular intervals when viewed from the central axis L1 of the rotating shaft 22.

  A segment conductor (SC) winding is wound around the 60 teeth 31. More specifically, 60 teeth 31 have two U-phase, V-phase, and V-phase three-phase windings in the clockwise direction, that is, a first system three-phase winding and a second system three-phase winding A line is formed.

  The first system three-phase winding and the second system three-phase winding wound around the stator core 30 of the present embodiment are distributed windings, and the first system U-phase winding U1 and the second system are clockwise. The U-phase winding U2, the first system V-phase winding V1, the second system V-phase winding V2, the first system W-phase winding W1, and the second system W-phase winding W2 are wound in this order. Specifically, the first system U-phase winding U1, the second system U-phase winding U2, the first system V-phase winding V1, the second system V-phase winding V2, the first system W-phase winding W1, the first system W-phase winding W1 The two-system W-phase winding W2 is wound in turn by shifting the teeth 31 one by one in order, with each of the six teeth 31 as one set.

  At this time, each phase winding U1, V1, W1 of the first system and each phase winding U2, V2, W2 of the second system, which are wound by distributed winding, are adjacent to each other in one stator side slot 32, respectively. The winding of the same phase will be wound.

  A three-phase power supply voltage having a phase difference of 30 ° is applied to the first system three-phase winding and the second system three-phase winding. That is, U-phase power supply voltage having a phase difference of 30 ° is applied to first system U-phase winding U1 and second system U-phase winding U2, and first system V-phase winding V1 and second system V-phase winding A V-phase power supply voltage having a phase difference of 30 ° is applied to the line V2, and a W-phase power supply voltage having a phase difference of 30 ° is applied to the first system W-phase winding W1 and the second system W-phase winding W2. Ru.

(Rotor 25)
The rotor 25 disposed inside the stator 21 includes a first rotor core 60, a second rotor core 70 disposed opposite to the first rotor core 60, and a first rotor core, as shown in FIGS. A disc magnet (field member) 75 disposed between the rotor 60 and the second rotor core 70 is provided.

(First rotor core 60)
As shown in FIGS. 8 to 11, the first rotor core 60 has a first core base 61 formed in a substantially disc shape. At a central position of the first core base 61, a through hole 62 for penetrating and fixing the rotary shaft 22 is formed. Further, on the outer peripheral surface of the first core base 61, a plurality of (five in the present embodiment) first projecting pieces 63 are projected radially outward at equal intervals, and the tip thereof is bent to axially second rotor core It is extended to the 70 side.

  The circumferential end surfaces 63a and 63b of the first projecting piece 63 are flat surfaces extending in the radial direction (not inclined with respect to the radial direction when viewed from the axial direction), and the first projecting piece 63 has a cross section in the axial orthogonal direction Are fan-shaped.

  The angle in the circumferential direction of each of the first protrusions 63, that is, the angle between the circumferential end surfaces 63a and 63b and the central axis L1 of the rotation shaft 22 is set between the adjacent first protrusions 63 and the first protrusions 63. It is set smaller than the angle of the gap.

(2nd rotor core 70)
As shown in FIGS. 8 to 11, the second rotor core 70 has the same shape as the first rotor core 60, and the rotation shaft 22 is provided at the center position of the second core base 71 formed in a substantially disc shape. A through hole 72 for penetrating and fixing is formed. Further, on the outer peripheral surface of the second core base 71, five second protrusions 73 are projected radially outward at equal intervals, and their tips are bent and extended to the first rotor core 60 side in the axial direction. ing.

The circumferential end surfaces 73a and 73b of the second projecting piece 73 are flat surfaces extending in the radial direction, and the second projecting piece 73 has a fan-shaped cross section in the axial orthogonal direction.
The angle in the circumferential direction of each of the second protrusions 73, that is, the angle between the circumferential end surfaces 73a and 73b and the central axis L1 of the rotation shaft 22 is set between the adjacent second protrusions 73 and the second protrusions 73. It is set smaller than the angle of the gap.

  Then, in the second rotor core 70, the second projecting pieces 73 of the second rotor core 70 are positioned between the first projecting pieces 63 of the first rotor core 60 when viewed from the axial direction with respect to the first rotor core 60, respectively. It is arranged to be fixed. At this time, the second rotor core 70 is assembled to the first rotor core 60 such that the disc magnet 75 is disposed between the first rotor core 60 and the second rotor core 70 in the axial direction.

  More specifically, as shown in FIG. 11, the disc magnet 75 has a surface (a facing surface 61 a) on the side of the second core base 71 of the first core base 61 and a side on the first core base 61 of the second core base 71. It is clamped between the faces (opposing face 71a).

  At this time, one end face 63a of the first protrusion 63 in the circumferential direction and the other end face 73b of the second protrusion 73 in the circumferential direction are formed parallel to each other along the axial direction. A gap between 63a and 73b is formed to be substantially linear along the axial direction. Further, since the other circumferential end face 63b of the first protrusion 63 and the one circumferential end face 73a of the second protrusion 73 are formed in parallel along the axial direction, both end faces 63b , 73a are formed so as to be substantially linear along the axial direction.

(Disc magnet 75)
In the present embodiment, the disc magnet 75 is a disc-shaped permanent magnet made of a neodymium magnet. As shown in FIG. 11, the disc magnet 75 is formed with a through hole 76 penetrating the rotation shaft 22 at the center position thereof. Then, one side surface 75 a of the disc magnet 75 abuts on the opposing surface 61 a of the first core base 61 and the other side surface 75 b of the disc magnet 75 on the opposing surface 71 a of the second core base 71. The plate magnet 75 is sandwiched and fixed between the first rotor core 60 and the second rotor core 70.

The outer diameter of the disk magnet 75 is set to match the outer diameter of the first and second core bases 61 and 71, and the thickness is set to a predetermined thickness.
That is, when the disc magnet 75 is disposed between the first rotor core 60 and the second rotor core 70, the tip surface 63c of the first projecting piece 63 and the opposite surface 71b of the second core base 71 are flush with each other. As a result, the tip end surface 73c of the second protrusion 73 and the opposite surface 61b of the first core base 61 are flush with each other.

  As shown in FIG. 9, the disc magnet 75 is magnetized in the axial direction, and is magnetized so that the first rotor core 60 side is N pole and the second rotor core 70 side is S pole. Therefore, by the disc magnet 75, the first projecting piece 63 of the first rotor core 60 functions as an N pole (first magnetic pole), and the second projecting piece 73 of the second rotor core 70 as an S pole (second magnetic pole) Function.

  As a result, the rotor 25 of this embodiment is a so-called Lundell type rotor using the disc magnet 75. Further, in the rotor 25 of the present embodiment, the first projecting piece 63 to be the N pole and the second projecting piece 73 to be the S pole are alternately arranged in the circumferential direction, and the number of magnetic poles is 10 ) Rotors. That is, in the rotor 25 of the present embodiment, the number of pole pairs is an odd number of 3 or more.

Next, the operation of the brushless motor M configured as described above will be described.
The first projecting piece 63 of the first rotor core 60 is projected radially outward from the outer peripheral surface of the first core base 61 and bent at its tip to extend toward the second rotor core 70 in the axial direction. Thus, the portion of the first protrusion 63 extending to the axial second rotor core 70 functions as an N pole. Further, the second projecting piece 73 of the second rotor core 70 is protruded radially outward from the outer peripheral surface of the second core base 71 and bent at its tip end so as to extend toward the first rotor core 60 in the axial direction. Thus, the portion of the second protrusion 73 extending to the axial first rotor core 60 side functions as an S pole. It is a function as a so-called Lundell structure.

  Further, since the rotor 25 has an odd number of pole pairs of 5, when viewed on a rotor core basis, the magnetic poles of the same pole do not face each other in the circumferential direction 180 °, so they have a shape stable against magnetic vibration. The low cogging torque and the low torque ripple can be improved to obtain a good steering feel.

  Further, the disc magnet 75 is a central portion of the rotor 25 and both axial direction sides thereof are the first and second core bases 61 and 71, and the circumferential outer surface is the first and second projecting pieces 63 and 73. Being in the enclosed state, it is possible to suppress the brake torque at the time of failure, and the steering is lightened by that amount, and the steering operation becomes easy.

Next, the second embodiment has the following effects in addition to the effects of the first embodiment.
(1) According to the above-described embodiment, the portion of the first protrusion 63 extending to the axial second rotor core 70 side functions as the N pole. Moreover, the part extended to the axial direction 1st rotor core 60 side of the 2nd protrusion 73 was made to function as a south pole. Therefore, the magnetic flux of the disc magnet 75 can be effectively utilized by the output improvement of the brushless motor M.

  (2) In the present embodiment, since the number of pole pairs of the rotor 25 is an odd number 5, the shape is stable against magnetic vibration, and low cogging torque and low torque ripple are improved to obtain a good steering feel. it can.

  (3) In the present embodiment, the disc magnet 75 is a central portion of the rotor 25 and is surrounded by the first and second core bases 61 and 71 and the first and second projecting pieces 63 and 73. Being disposed, it is possible to suppress the brake torque at the time of failure.

Third Embodiment
Next, a third embodiment of the present invention will be described according to FIG. 12 and FIG.
The present embodiment is characterized in that it is a so-called tandem type in which two rotors 25 of the second embodiment are stacked. Therefore, the characteristic parts will be described in detail, and the common parts will not be described in detail.

As shown in FIGS. 12 and 13, the rotor 80 of the brushless motor M according to this embodiment has a front side rotor 81 and a rear side rotor 82.
The front side rotor 81 has the same configuration as the rotor 25 of the second embodiment, and includes a first rotor core 60 having a first projecting piece 63, a second rotor core 70 having a second projecting piece 73, and a disc magnet ( A field member 75 is provided.

  The rear side rotor 82 has the same configuration as the rotor 25 of the second embodiment, and includes a first rotor core 60 having a first projecting piece 63, a second rotor core 70 having a second projecting piece 73, and a disc magnet ( A field member 75 is provided.

  Then, when the front side rotor 81 and the rear side rotor 82 are overlapped, the second rotor core 70 of the front side rotor 81 and the second rotor core 70 of the rear side rotor 82 are brought into contact with each other, and the rotor 80 rotates. It is fixed to the shaft 22.

Next, the operation of the third embodiment configured as described above will be described below.
The rotor 80 is formed in a tandem structure in which the front side rotor 81 and the rear side rotor 82 having the same shape are stacked to form a small-sized, high-power motor.

Moreover, since the front side rotor 81 and the rear side rotor 82 are formed with the same shape and the same material, parts management and an assembly operation at the time of assembling the rotor 80 become easy.
According to the third embodiment, in addition to the effects of the second embodiment, a smaller and higher power motor can be realized.

Fourth Embodiment
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, a new configuration is added to the rotor 25 of the second embodiment. Therefore, the newly added part of the configuration will be described in detail, and the detailed description of the common parts will be omitted.

  As shown in FIGS. 14 and 15, between the circumferential end face 63a of the first protrusion 63 and the circumferential end face 73b of the second protrusion 73, a square pole-shaped first interpole magnet 85 which is axially long is provided. Are each clamped and fixed. The first inter-pole magnet 85 is formed to extend until the radially inner side surface abuts on the first and second core bases 61 and 71 and the radially outer side surface of the first and second projecting pieces 63 and 73. It is formed so as to be flush with the outer peripheral surface.

  Each first interpole magnet 85 is a ferrite magnet, is magnetized in the circumferential direction, and functions as an S pole so that the side of the first protrusion 63 functioning as the N pole is the N pole of the same pole The second projecting piece 73 side is magnetized so as to be the same pole S pole.

  On the other hand, as shown in FIG. 14 and FIG. 15, between the circumferential end face 63 b of the first protrusion 63 and the circumferential end face 73 a of the second protrusion 73, a square pole-shaped second pole which is long in the axial direction Magnets 86 are respectively clamped and fixed. The second inter-pole magnet 86 is formed to extend until the radially inner side surface abuts on the first and second core bases 61 and 71, and the radially outer side surface is formed of the first and second projecting pieces 63 and 73. It is formed so as to be flush with the outer peripheral surface.

  Each second inter-pole magnet 86 is a ferrite magnet, is magnetized in the circumferential direction, and functions as an S pole so that the side of the first protrusion 63 functioning as the N pole becomes the N pole of the same pole The second projecting piece 73 side is magnetized so as to be the same pole S pole.

That is, the magnetization direction of the first inter-pole magnet 85 and the second inter-pole magnet 86 is oppositely magnetized in the circumferential direction.
Further, as shown in FIG. 14, by forming the first and second inter-pole magnets 85 and 86, the inner circumference of the second projecting piece 73 is between the first and second inter-pole magnets 85 and 86. The first back magnet 87 is fitted and fixed in a space opened by the surface and the outer peripheral surface formed by the first core base 61 and the disc magnet 75 on the side of the first rotor core 60. The first back magnet 87 is a ferrite magnet and is radially magnetized so that the side in contact with the second projecting piece 73 becomes the S pole of the same pole as that of the second projecting piece 73. The side in contact with the core base 61 is magnetized so as to be the N pole of the same polarity as the first core base 61.

  Similarly, as shown in FIG. 15, it is formed between the first and second inter-pole magnets 85 and 86 and by the inner peripheral surface of the first projecting piece 63, the second core base 71 and the disc magnet 75. The second back magnet 88 is fitted and fixed in a space opened by the second rotor core 70 formed by the outer peripheral surface to be formed. The second back magnet 88 is a ferrite magnet and is radially magnetized so that the side in contact with the first projecting piece 63 is the N pole of the same pole as the first projecting piece 63. The side in contact with the core base 71 is magnetized so as to be the S pole of the same polarity as the second core base 71.

Next, the operation of the fourth embodiment configured as described above will be described below.
In the portion of the first core base 61, the second protrusion 73 functioning as the first back surface magnet 87 having the south pole on the stator 21 side and the first protrusion 63 functioning as the salient pole of the N position by the first back surface magnet 87 And form a rotor alternately formed in the circumferential direction.

  Further, in the portion of the second core base 71, the stator 21 side functions as the salient pole of the S pole by the first projecting piece 63 functioning as the second back magnet 88 of the N pole and the second back magnet 88 The pieces 73 form a rotor alternately formed in the circumferential direction.

  Furthermore, in the portion of the disc magnet 75, the first projecting piece 63 in which the side of the stator 21 functions as an N pole by the first back surface magnet 87 and the second projecting piece in which the side of the stator 21 functions as an S pole by the second back surface magnet 88 And 73 form a rotor having a Lundell structure which is alternately formed in the circumferential direction.

Next, the fourth embodiment has the following effect in addition to the effects of the first and second embodiments.
(1) According to the above-described embodiment, the first and second magnetized pieces 63 and 73 have the same polarity between the first and second protruding pieces 63 and 73. Magnets 85 and 86 between two poles are provided. It is possible to reduce the magnetic flux leakage between the respective first projecting pieces 63 of the first rotor core and the respective second projecting pieces 73 of the second rotor core, and the magnetic flux of the disc magnet 75 is effectively utilized by the output improvement of the brushless motor M. can do.

  (2) According to the above-described embodiment, the portion of the first core base 61 becomes a rotor that makes the flow of the desired magnetic flux by the first back surface magnet 87, so that the short circuit magnetic flux of the disc magnet 75 can be suppressed. The magnetic flux of the back surface magnet 87 can be more effectively used for the output of the brushless motor M.

  (3) According to the above embodiment, the portion of the second core base 71 becomes a rotor that makes the flow of the desired magnetic flux by the second back surface magnet 88, so that the short circuit magnetic flux of the disc magnet 75 can be suppressed. The magnetic flux of the back surface magnet 88 can be more effectively used for the output of the brushless motor M.

The above embodiment may be modified as follows.
In each of the above embodiments, the disc magnets 55 and 75 as field members are implemented with neodymium magnets, but the present invention is not limited to this. Ferrite magnets, samarium iron nitride magnets, samarium cobalt magnets, etc., and other permanent magnets It may be implemented in

  In the third embodiment, the rotor 25 of the second embodiment has a tandem structure, but the rotor 25 shown in the first embodiment and the rotor 25 shown in the fourth embodiment have a tandem structure. It is also good.

In the above embodiments, the outer diameter of the motor housing 20a is 10 cm, but may be 10 cm or less.
In the first embodiment, the concentrated winding is embodied as a brushless motor M having 14 poles and 12 slots, but the invention is not limited to this. For example, the present invention may be applied to a brushless motor which is concentrated winding and has 8 poles and 12 slots, 10 poles and 12 slots, 16 poles and 12 slots, 12 poles and 18 slots, 16 poles and 18 slots, and 20 poles and 18 slots.

  In the second embodiment, although the present invention is embodied as a distributed winding, brushless motor M with 10 poles and 60 slots, the present invention is not limited to this. For example, it is a distributed winding and is brushless such as 6 poles 18 slots, 6 poles 36 slots, 6 poles 72 slots, 8 poles 24 slots, 8 poles 48 slots, 10 poles 30 slots, 16 poles 48 slots, 20 poles 60 slots, etc. It may be applied to a motor. In other words, it may be a slot that is a multiple of the pole number.

  -Although the brushless motor M of each said embodiment was actualized in the electric power steering system 1 of a column assist type, you may apply this to the electric power steering assist system of a rack assist type or a pinion assist type. In this case, since it is disposed in the engine room, the effect is particularly large.

The following describes other technical ideas.
(Supplementary Note 1) A rotor of a motor for an electric power steering system for applying assist torque to a steering wheel, wherein a first rotor core having a plurality of first protrusions formed at equal intervals in a circumferential direction, and the first rotor core A plurality of second protrusions are formed at equal intervals in the circumferential direction, having the same shape as the rotor core, and the second protrusions are positioned between the first protrusions of the first rotor core and the first protrusions in the axial direction. And a second rotor core disposed relative to the first rotor core, and disposed between the first rotor core and the second rotor core and axially magnetized to form a first protrusion of the first rotor core. A field member for generating a first magnetic pole on one piece and a second magnetic pole on a second projecting piece of the second rotor core, the first rotor core being a disc-shaped first member fixed to a rotation shaft. Core base The first core base is formed with a first projection in the radial direction from the outer peripheral surface, and the second rotor core has a disc-shaped second core base fixed to the rotation shaft. A second projection formed radially from an outer peripheral surface of the second core base, and the field member has a disc whose outer diameter is the same as the outer diameter of the first and second core bases -Shaped permanent magnet, the first projecting piece formed on the first core base is projected radially outward and the tip is bent to extend toward the second rotor core in the axial direction, and the second core is formed The second projecting piece formed on the base is projected radially outward, and the tip is bent so that the second projecting piece is extended toward the first rotor core in the axial direction, and the first projecting piece and the second projecting piece Between the circumferential direction, an inter-pole magnet magnetized in the circumferential direction is provided, and the diameter of the first protrusion is provided. The radially inner direction inside and the second protrusion, the rear magnet is provided which is magnetized in the radial direction.

  According to the configuration, the field member is shielded from external temperature changes by the first and second rotor cores to improve heat resistance, and demagnetization due to the rotating magnetic field can be made difficult to occur under a wide range of external temperature environments. In addition, since the field member is disposed between the first rotor core and the second rotor core and axially held, the size of the motor can be reduced and scattering of the field member due to centrifugal force is prevented. it can.

  Also, the field member is disposed between the first core base and the second core base. Then, a first magnetic pole is generated on a first protrusion formed to extend from the first core base of the first rotor core by the field member, and a second protrusion is formed to extend from the second core base of the second rotor core. A second magnetic pole is generated on one of the pieces.

  Further, the first projecting piece generated by the first magnetic pole is projected radially outward from the outer peripheral surface of the first core base, and the tip is bent to extend toward the second rotor core in the axial direction. Further, the second projecting piece generated by the second magnetic pole is projected radially outward from the outer peripheral surface of the second core base, and the tip is bent to extend toward the first rotor core in the axial direction.

  (Supplementary Note 2) In the rotor of the motor for an electric power steering system, the field member is a disk-shaped permanent magnet made of any one of a ferrite magnet, a neodymium magnet, a samarium iron nitride magnet, and a samarium cobalt magnet. .

  According to the configuration, the field member is a disk-shaped permanent magnet, and is a disk-shaped permanent magnet made of any one of a ferrite magnet, a neodymium magnet, a samarium iron nitride magnet, and a samarium cobalt magnet. The first protrusion generates a first magnetic pole, and the second protrusion generates a second magnetic pole.

(Supplementary Note 3) In the rotor of the motor for an electric power steering system, the axial length of one set of the rotor is a half or less of the outer diameter of the rotor.
According to this configuration, the axial length of the rotor can be reduced to 1/2 or less of the outer diameter of the rotor, whereby the axial size of the motor can be reduced.

(Supplementary Note 4) A rotor of a motor for an electric power steering system in which a plurality of the rotors are stacked.
According to this configuration, the output of the motor can be improved.

(Supplementary Note 5) A motor for an electric power steering system including the rotor of the motor for an electric power steering system.
According to the same configuration, it is possible to make it difficult to change the characteristics of the permanent magnet provided on the rotor, and it is possible to achieve both a low torque pulsation and a high torque and obtain a good steering feel.

  (Supplementary Note 6) In the motor for an electric power steering system, the motor for an electric power steering system is used for any of a column assist type, rack assist type, and pinion assist type electric power steering system.

According to this configuration, it is possible to achieve both a low torque pulsation and a high torque and obtain a good steering feel.
(Supplementary Note 7) In the motor for an electric power steering system, the motor for an electric power steering system is concentrated winding, and has 8 poles 12 slots, 10 poles 12 slots, 14 poles 12 slots, 16 poles 12 slots, 12 poles There are 18 slots, 16 poles and 18 slots, and 20 poles and 18 slots.

According to this configuration, it is possible to achieve both a low torque pulsation and a high torque and obtain a good steering feel.
(Supplementary Note 8) In the motor for the electric power steering system, the motor for the electric power steering system is distributed winding, and has 6 poles 18 slots, 6 poles 36 slots, 6 poles 72 slots, 8 poles 24 slots, 8 poles One of 48 slots, 10 poles and 30 slots, 10 poles and 60 slots, 16 poles and 48 slots, and 20 poles and 60 slots.

  According to this configuration, it is possible to achieve both a low torque pulsation and a high torque and obtain a good steering feel.

DESCRIPTION OF SYMBOLS 1 ... Electric power steering system, 2 ... Steering wheel, 3 ... Steering shaft, 3a ... Input axis, 3b ... Output axis, 4 ... Universal joint, 5 ... Intermediate, 7 ... Rack, 8 ... Pinion axis, 9 ... Tie rod, DESCRIPTION OF SYMBOLS 10 ... Steering wheel, 11 ... Steering column, 20 ... Motor case, 20a ... Motor housing, 20b ... Front cover, 21 ... Stator, 22 ... Rotation axis, 23, 24 ... Bearing, 25 ... Rotor, 26, 27 ... Gear, 28: Reduction gear, 30: Stator core, 31: Teeth, 32: Stator side slot, 33a: U phase winding, 33b: V phase winding, 33c: W phase winding, 40: first rotor core, 41: 1st Core base, 42: through hole, 43: first projecting piece, 50: second rotor core, 51: second core base, 52: through hole, 53: fifth Protruding pieces 55: disc magnets 55a, 55b: sides 56: through holes 60: first rotor core 61: first core base 61a: facing surface 61b: facing opposite surface 62: through hole 63 ... first projecting piece, 63a, 63b ... circumferential end surface, 63c ... tip surface, 70 ... second rotor core, 71 ... second core base, 71a ... opposing surface, 71b ... opposing surface, 72 ... through hole, 73 ... Second projecting piece 73a, 73b: circumferential end face, 73c: tip end face, 75: disc magnet, 75a, 75b: side face, 76: through hole, 80: rotor, 81: front side rotor, 82: rear side rotor 85: first interpole magnet 86: second interpole magnet 87: first back magnet 88 second back magnet M: three-phase brushless motor L1 central axis U1: first system U-phase Winding, U2 ... second system U phase winding, V1 ... first system V phase winding V2 ... second system V-phase winding, W1 ... first line W-phase winding, W2 ... second system W-phase winding.

Claims (3)

Motor case,
A stator disposed in the motor case and wound with a winding;
A rotor disposed inside the stator;
A vehicle brushless motor comprising: a rotating shaft made of a nonmagnetic material fixed to the rotor and drivingly connected to a reduction gear at a portion protruding from the motor case,
The rotor is
A first rotor core having a plurality of first protrusions formed at equal intervals in a circumferential direction;
A plurality of second protrusions are formed at equal intervals in the circumferential direction, having the same shape as the first rotor core, and the second protrusions are the first protrusions and the first protrusions of the first rotor core in the axial direction. A second rotor core disposed relative to the first rotor core so as to be positioned therebetween;
The first magnetic pole is disposed between the first rotor core and the second rotor core and is magnetized in the axial direction, and the first magnetic pole is disposed on the first projecting piece of the first rotor core, and the second projecting piece is disposed on the second projecting piece of the second rotor core. And field members for generating magnetic poles respectively,
The first rotor core has a disk-shaped first core base fixed to the rotary shaft, and a first projection is formed on the first core base in the radial direction from the outer peripheral surface,
The second rotor core has a disk-shaped second core base fixed to the rotary shaft, and a second projection is formed on the second core base in the radial direction from the outer peripheral surface,
A gear of the reduction gear is provided coaxially with the rotor in the motor case at a portion of the rotation shaft projecting from the motor case when viewed from a direction orthogonal to the axial direction of the rotation shaft.
The field member has an outer diameter equal to the outer diameter of the first and second core bases and is larger than the outer diameter of the gear and has an axial thickness of the first and second core bases. It is a disk-shaped permanent magnet thinner than its axial thickness ,
The first projecting piece formed on the first core base is projected radially outward, the tip is bent, and is extended toward the second rotor core in the axial direction,
A brushless motor for a vehicle, wherein the second projecting piece formed on the second core base is protruded radially outward and a tip thereof is bent so as to extend toward the axial first rotor core side.   The vehicle brushless motor according to claim 1, wherein the winding wound on the stator is supplied with a three-phase drive current. Between the circumferential direction of said 1st protrusion and said 2nd protrusion, while the pole magnet magnetized in the circumferential direction is provided, the radial inside of said 1st protrusion and the 2nd protrusion of The vehicle brushless motor according to claim 1, wherein a radially magnetized back magnet is provided radially inward.