JP2018182999A - Rotor and electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor and an electric motor which are arranged to be able to exhibit satisfactory motor characteristics in all load regions.SOLUTION: A rotor comprises: a rotation shaft 31 which rotates around a shaft center C1; a rotor core 32 fixed to the rotation shaft 31; and a plurality of permanent magnets 33 provided in the rotor core 32, of which sectional shapes orthogonal to the shaft center C1 extend in a radial direction of the rotor core 32 and are disposed radially. Center slits 71 are formed at all centers between two permanent magnets 33 adjacent to each other in a circumferential direction of the rotor core 32, of which sectional shapes orthogonal to the shaft center C1 extend in a radial direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rotor and an electric motor.

  Among the electric motors, there is a brushless motor provided with a stator having teeth wound with a coil, and a rotor rotatably provided radially inward of the stator. A linkage flux is formed on the stator by supplying power to the coil. The rotor has a rotating shaft, a substantially cylindrical rotor core externally fitted and fixed to the rotating shaft, and a permanent magnet provided on the rotor core. Then, a magnetic attraction force or repulsive force is generated between the linkage flux formed in the stator and the permanent magnet provided in the rotor core, and the rotor is continuously rotated.

Here, as a system which arranges a permanent magnet in a rotor, a permanent magnet embedded system (IPM: Interior Permanent Magnet) which forms a plurality of slits in a rotor core and arranges a permanent magnet in a slit is known.
Also, in recent years, among IPM motors, permanent magnets are arranged (radially) along the radial direction in the rotor core, and a large reluctance torque is generated by giving the permanent magnets a shape with strong magnetic anisotropy. PMR (Permanent Magnetic Reluctance) motors are known. Also, with this type of motor, it is possible to converge the magnetic flux of the permanent magnet on the rotor core between the circumferentially adjacent permanent magnets to obtain high torque.

Japanese Patent Application Laid-Open No. 11-89133 JP, 2010-4722, A

  By the way, in the above-mentioned prior art, the interlinkage magnetic flux formed of the stator passes through the rotor core between the circumferentially adjacent permanent magnets. For this reason, there is a possibility that the magnetic flux formed by the permanent magnet is affected by the interlinking magnetic flux of the stator, and a load region in which the motor characteristics are degraded is created.

  Then, this invention is made in view of the situation mentioned above, Comprising: The rotor and electric motor which can exhibit sufficient motor characteristics in all the load area | regions are provided.

  In order to solve the above-mentioned problems, a rotor according to the present invention is provided in a shaft rotating around a rotation axis, a rotor core fixed to the shaft and having the rotation axis as a radial center, and in the rotor core And a plurality of permanent magnets arranged radially so that the cross-sectional shape orthogonal to the rotation axis is along the radial direction of the rotor core, and between the two permanent magnets adjacent in the circumferential direction of the rotor core At the center, a center slit is formed in all of which the cross-sectional shape orthogonal to the rotation axis extends in the radial direction.

  By this configuration, the magnetic path of the d-axis, which is the magnetic path of the magnetic flux of the permanent magnet provided in the rotor core, is not blocked by the center slit. On the other hand, the center slit interrupts the q-axis (axis orthogonal to the d-axis) magnetic path which is a magnetic path on the rotor core side of the linkage flux formed by the stator. Therefore, q-axis magnetic flux is less likely to be formed on the rotor core. Therefore, the influence of the flux linkage (q-axis flux) on the d-axis flux can be reduced, and sufficient motor characteristics can be exhibited in all load regions.

  In the rotor according to the present invention, in the rotor core, a plurality of magnetic flux densities on the outer peripheral surface formed by the permanent magnets become larger toward the center between two adjacent permanent magnets in the circumferential direction. A side slit is formed.

With this configuration, in the rotor core, the q-axis magnetic paths are blocked at a plurality of locations by the plurality of side slits. Therefore, q-axis magnetic flux is less likely to be formed on the rotor core more reliably. As a result, the influence of the linkage flux (q-axis flux) on the d-axis flux can be more reliably prevented, and sufficient motor characteristics can be exhibited in all load regions.
Further, on the outer peripheral surface of the rotor core, the magnetic flux of the permanent magnet is induced to the center between the two permanent magnets adjacent in the circumferential direction (hereinafter referred to as the circumferential center of the rotor core per pole). The magnetic flux density at the circumferential center can be made as high as possible. Furthermore, on the outer peripheral surface of the rotor core, the magnetic flux density of the permanent magnet can be lowered as it approaches the permanent magnet. That is, since the peak width of the sine waveform of the magnetic flux density formed on the outer peripheral surface of the rotor core is narrowed and the saliency is improved, the torque performance of the electric motor can be improved.

  In the rotor according to the present invention, the plurality of side slits are formed such that a cross-sectional shape orthogonal to the rotation axis extends from the immediate vicinity of the circumferential side surface of the permanent magnet toward the outer peripheral surface of the rotor core In the gap between the center slit and the side slit, the gap on the nearest side of the permanent magnet is set larger than the gap on the outer peripheral surface side of the rotor core.

  With this configuration, the magnetic flux of the permanent magnet can be reliably guided to the circumferential center of the rotor core per one pole. Therefore, the magnetic flux density in the circumferential center of the rotor core per one pole can be reliably increased. Therefore, the torque performance of the electric motor can be reliably improved.

  In the rotor according to the present invention, the side slit has a curved cross-sectional shape orthogonal to the rotation axis.

  With this configuration, the peak width of the sine waveform of the magnetic flux density formed on the outer peripheral surface of the rotor core can be more reliably narrowed, and saliency can be reliably improved. Therefore, the torque performance of the electric motor can be more reliably improved.

  In the rotor according to the present invention, the side slit is curved so that a cross-sectional shape orthogonal to the rotation axis is convex toward the center slit. In the cross-sectional shape of the side slit, the permanent magnet The extension direction of the most immediate side of the circumferential side face is along the direction orthogonal to the circumferential side face of the permanent magnet, and the extension direction of the outer peripheral surface side of the rotor core is the extension direction of the center slit It is characterized by

  With this configuration, the magnetic flux of the permanent magnet can be reliably guided to the circumferential center of the rotor core per one pole. Therefore, the magnetic flux density in the circumferential center of the rotor core per one pole can be reliably increased. Further, the peak width of the sine waveform of the magnetic flux density formed on the outer peripheral surface of the rotor core can be more reliably narrowed, and the saliency can be more reliably improved. Therefore, the torque performance of the electric motor can be more reliably improved.

  In the rotor according to the present invention, the permanent magnet is formed in a trapezoidal shape so that the width in the circumferential direction gradually becomes wider as the sectional shape orthogonal to the rotation axis goes radially inward.

  Thus, by making the permanent magnet trapezoidal, it is possible to reduce the magnetic flux leaking inward in the radial direction of the permanent magnet. Further, the magnetic flux can be concentrated at the circumferential center of the rotor core per one pole without bringing the adjacent permanent magnets in the circumferential direction close to each other. Therefore, the motor characteristics of the electric motor can be improved.

  An electric motor according to the present invention comprises the rotor described above, and a stator formed in an annular shape so as to surround the outer periphery of the rotor and having a plurality of teeth around which a coil for generating a magnetic field is wound. It is characterized by

  With this configuration, it is possible to provide an electric motor that can exhibit sufficient motor characteristics in all load regions.

  According to the present invention, the center slit can shut off the q-axis magnetic path of the rotor core. Therefore, the q-axis magnetic flux is less likely to be formed in the rotor core, and the influence of the interlinking flux (q-axis flux) on the d-axis magnetic flux can be reduced. Therefore, sufficient motor characteristics can be exhibited in all load regions.

It is a perspective view of a motor with a reduction gear in an embodiment of the present invention. It is sectional drawing in alignment with the AA of FIG. It is the top view seen from the axial direction of the stator in embodiment of this invention, and a rotor. It is the figure which expanded the rotor of FIG. It is the B section enlarged view of FIG. It is a figure which shows the magnetic flux vector of the teeth and rotor core in embodiment of this invention. It is a figure which shows the magnetic flux vector of the teeth in a conventional rotor core, and a rotor core. It is a figure which shows the magnetic flux density of the magnetic flux formed in each of the teeth and rotor core in embodiment of this invention. When each side slit is formed in the rotor core in parallel with the center slit, it is a figure which shows the magnetic flux density of the magnetic flux formed in each of teeth and a rotor core. It is a graph which shows the change of the interlinkage magnetic flux for three phases formed in the outer peripheral surface of the rotor core in embodiment of this invention. It is a graph which shows the change of the interlinkage magnetic flux for three phases formed in the outer peripheral surface of the conventional rotor core. It is a graph which shows the change of the rotation speed and torque of the rotor in embodiment of this invention, and a conventional rotor. It is the top view seen from the axial direction of the rotor core in the modification of embodiment of this invention, Comprising: (a) is one slit number, (b) shows three slits, (c) shows five slits. It is a graph which shows the change of the effective magnetic flux for every slit formed in the rotor core in embodiment of this invention. It is a graph which shows the change of the rotation speed for every slit formed in the rotor core in embodiment of this invention, and a torque. It is the top view seen from the axial direction of the rotor core in the modification of embodiment of this invention. It is a graph which shows the change of the torque for every slit formed in the rotor core in embodiment of this invention, and a rotation angle. FIG. 18 is a graph comparing each slit formed in the rotor core with the scale of the horizontal axis in FIG. 17 reduced. It is the graph which compared the torque ripple rate of every slit formed in the rotor core in embodiment of this invention, and the conventional rotor core. It is the top view seen from the axial direction of the stator in the modification of embodiment of this invention, and a rotor. It is the top view seen from the axial direction of the stator in the modification of embodiment of this invention, and a rotor. It is the top view seen from the axial direction of the stator in the modification of embodiment of this invention, and a rotor.

  Next, an embodiment of the present invention will be described based on the drawings.

(Motor with reduction gear)
FIG. 1 is a perspective view of the motor 1 with a reduction gear, and FIG. 2 is a cross-sectional view taken along the line A-A of FIG.
As shown in FIGS. 1 and 2, the motor 1 with a reduction gear serves as a drive source of, for example, electrical components (for example, a wiper, a power window, a sunroof, an electric seat, etc.) mounted on a vehicle. The motor with a reduction gear 1 includes a motor unit 2, a reduction unit 3 that decelerates and outputs rotation of the motor unit 2, and a controller unit 4 that performs drive control of the motor unit 2.
In the following description, the term "axial direction" refers to the axial direction of the rotary shaft 31 of the motor unit 2, and the term "circumferential direction" refers to the circumferential direction of the rotary shaft 31, and the term "radial direction" The radial direction of the rotating shaft 31 shall be said.

(Motor part)
The motor unit 2 includes a motor case 5, a substantially cylindrical stator 8 housed in the motor case 5, and a rotor 9 provided radially inward of the stator 8 and provided rotatably with respect to the stator 8. And have.

(Motor case)
The motor case 5 is formed of, for example, a material excellent in heat dissipation such as aluminum die casting. The motor case 5 includes a first motor case 6 and a second motor case 7 which can be divided in the axial direction. The first motor case 6 and the second motor case 7 are each formed in a bottomed cylindrical shape.
The first motor case 6 is integrally formed with the gear case 40 so that the bottom portion 10 is joined to the gear case 40 of the speed reduction unit 3. A through hole 10 a through which the rotation shaft 31 of the rotor 9 can be inserted is formed substantially in the center of the bottom portion 10 in the radial direction.

  In addition, the fitting portion 16 is formed in the opening 6 a of the first motor case 6, and the fitting portion 17 is formed in the opening 7 a of the second motor case 7. The fitting portions 16 and 17 are engaged with each other to form a motor case 5 having an internal space. The stator 8 is disposed in the internal space of the motor case 5 so as to be fitted into the first motor case 6 and the second motor case 7.

(Stator)
FIG. 3 is a plan view seen from the axial direction of the stator 8 and the rotor 9.
As shown in FIGS. 2 and 3, the stator 8 has a tubular core portion 21 whose cross-sectional shape along the radial direction is substantially regular hexagon, and a plurality (for example, radially inward projecting from the core portion 21). In the present embodiment, six teeth 22) have a stator core 20 integrally formed.
The stator core 20 is formed by laminating a plurality of metal plates in the axial direction. The stator core 20 is not limited to the case where the plurality of metal plates are stacked in the axial direction, and may be formed, for example, by pressure molding soft magnetic powder.

  The teeth 22 are integrally formed of a tooth main body 101 protruding in a radial direction from an inner peripheral surface of the core portion 21 and a flange portion 102 extending in a circumferential direction from a radial inner end of the tooth main body 101 It is. The collar portion 102 is formed to extend from the tooth main body 101 in the circumferential direction. Then, the slots 19 are formed between the ridges 102 adjacent in the circumferential direction.

  Further, the inner peripheral surface of the core portion 21 and the teeth 22 are covered with an insulator 23 made of resin. A coil 24 (see FIG. 2, not shown in FIG. 3) is wound around each tooth 22 from above the insulator 23. Each coil 24 generates a magnetic field for rotating the rotor 9 by power feeding from the controller unit 4.

(Rotor)
FIG. 4 is an enlarged view of the rotor 9 of FIG.
As shown in the figure, the rotor 9 has a rotary shaft 31, a cylindrical rotor core 32 fixed to the rotary shaft 31 with the rotary shaft 31 as an axial center C 1, and a permanent magnet embedded in the rotor core 32. And 33.
The rotating shaft 31 is integrally formed with the worm shaft 44 that constitutes the speed reduction unit 3 (see FIG. 2). The rotor core 32 is formed by laminating a plurality of metal plates in the axial direction. The rotor core 32 is not limited to the case where the plurality of metal plates are stacked in the axial direction, and may be formed, for example, by pressure molding soft magnetic powder.

A minute gap S1 is formed between the outer peripheral surface 32b of the rotor core 32 and the inner peripheral surface of the flange portion 102 of the teeth 22. Further, a through hole 32 a penetrating in the axial direction is formed at substantially the center of the rotor core 32 in the radial direction. The rotary shaft 31 is press-fitted into the through hole 32a. The rotary shaft 31 may be inserted into the through hole 32a, and the rotor core 32 may be externally fixed to the rotary shaft 31 using an adhesive or the like.
Further, in the rotor core 32, four hollow portions 111 extending in the radial direction are formed at equal intervals (radially) in the circumferential direction.

The hollow portion 111 is formed such that the magnet housing portion 112 formed in the major part in the radial direction and the flux barrier portion 113 formed in the radial direction inner side of the magnet housing portion 112 communicate with each other.
The permanent magnet 33 is stored in the magnet storage unit 112. The magnet storage portion 112 is formed in a substantially equal leg trapezoidal shape such that the width in the circumferential direction gradually becomes wider as the cross-sectional shape along the radial direction goes inward in the radial direction.

  The flux barrier portion 113 is for suppressing the leakage of the magnetic flux of the permanent magnet 33 to the radially inner side of the rotor core 32 than the permanent magnet 33. Two flux barrier portions 113 are formed in one hollow portion 111. The two flux barrier portions 113 are disposed at the radially inner end of the magnet housing portion 112 and at both ends in the circumferential direction. By forming a plurality of flux barrier portions 113, a ring portion 115 having a through hole 32a is formed inward of the flux barrier portion 113 of the rotor core 32 in the radial direction.

Further, in the rotor core 32, between the two flux barrier portions 113 formed in one hollow portion 111, a convex streak portion 114 extending in the radial direction outward and along the axial direction is formed. It becomes a form. In other words, the ridges 114 are formed between the flux barrier portions 113 on the outer peripheral surface of the ring portion 115.
The radially outer end (tip) 114 a of the ridge portion 114 is formed flat so as to coincide with the position corresponding to the lower bottom of the magnet housing portion 112. That is, the below-described lower base 33 a of the permanent magnet 33 is abutted against the radially outer end 114 a of the protruding portion 114.

  In addition, bridge portions 116 are formed between the hollow portions 111 adjacent in the circumferential direction and between the flux barrier portions 113 adjacent in the circumferential direction. The bridge portion 116 serves to enhance the rigidity of the region where the flux barrier portion 113 of the rotor core 32 is formed, and to integrate the ring portion 115 and the rotor core 32 on the side where the magnet housing portion 112 is formed. ing.

  Further, in the outer peripheral surface 32 b of the rotor core 32, an opening 117 communicating with the hollow portion 111 is formed at a position corresponding to each hollow portion 111. The opening 117 is formed to such an extent that the permanent magnet 33 does not come out from the magnet housing portion 112 radially outward. Further, on both sides in the circumferential direction of each opening 117, grooves 119 are formed over the entire axial direction. The groove portion 119 is formed in a substantially triangular shape so as to be tapered inward in the radial direction.

  Furthermore, in the rotor core 32, center slits 71 are respectively formed at the centers between the magnet housing portions 112 adjacent in the circumferential direction (the circumferential center of the rotor core 32 per pole). The center slit 71 is an oval hollow portion which penetrates the rotor core 32 in the axial direction and the cross-sectional shape along the radial direction extends in the radial direction. The radially inner end of the center slit 71 extends to the front of the bridge portion 116. The radially outer end of the center slit 71 extends to the front of the outer peripheral surface 32 b of the rotor core 32. That is, an in-center bridge 75 a is formed between the radially inner end of the center slit 71 and the bridge portion 116. A center outer bridge 75 b is formed between the radially outer end of the center slit 71 and the outer peripheral surface 32 b of the rotor core 32.

Further, in the rotor core 32, two side slits 72 and 73 are formed on both sides in the circumferential direction of the center slit 71, respectively. The two side slits 72 and 73 are configured by a first side slit 72 disposed on the center slit 71 side and a second side slit 73 disposed on the magnet storage portion 112 side.
Each of the side slits 72 and 73 is a hollow portion which penetrates the rotor core 32 in the axial direction and is curved so that the cross-sectional shape along the radial direction is convex toward the center slit 71 side. And each side slit 72, 73 is formed in the oval shape as a whole.

  The radially inner ends of the side slits 72 and 73 extend to the front of the magnet storage portion 112. The radially outer ends of the side slits 72 and 73 extend to the front of the outer peripheral surface 32 b of the rotor core 32. That is, the first inner side bridge 76 a is formed between the radially inner end of the first side slit 72 and the magnet storage portion 112. Further, a first side outer bridge 76 b is formed between the radially outer end of the first side slit 72 and the outer peripheral surface 32 b of the rotor core 32. Furthermore, a second inner side bridge 77 a is formed between the radially inner end of the second side slit 72 and the magnet housing portion 112. Further, a second side outer bridge 77 b is formed between the radially outer end of the second side slit 72 and the outer peripheral surface 32 b of the rotor core 32.

  Further, the extending direction of the radially inner end of each side slit 72, 73 is in the direction substantially orthogonal to the circumferential side surface of the magnet housing portion 112. Furthermore, the extension direction of the radial direction outer end of each side slit 72, 73 is along the extension direction of the center slit 71.

The extension direction of each end of the side slits 72 and 73 will be described in more detail based on FIG.
FIG. 5 is an enlarged view of a portion B of FIG.
As shown in the figure, the inner peripheral surface of each side slit 72, 73 is formed by the two inner side surfaces 72a, 73a extending in the longitudinal direction and the two radial inner ends of the two inner side surfaces 72a, 73a respectively. It is comprised by arc surface 72b, 72c, 73b, 73c formed so that side surface 72a, 73a might be straddled.

  Here, the extension direction of the radially inner end of the first side slit 72 refers to the direction of the tangent L1 at the connecting portion (inflection point) of the inner side surface 72a and the radially inner arc surface 72b. The tangent L1 is substantially orthogonal to the circumferential side surface of the magnet housing portion 112. Further, the extending direction of the radially outer end of the first side slit 72 refers to the direction of the tangent L2 at the connecting portion (inflection point) of the inner side surface 72a and the radially outer arc surface 72c. The tangent L2 is along the extension direction of the center slit 71, that is, the extension direction of the center slit 71.

Further, the extending direction of the radially inner end of the second side slit 73 refers to the direction of the tangent L3 at the connecting portion (inflection point) of the inner side surface 73a and the radially inner arc surface 73b. The tangent L3 is substantially orthogonal to the circumferential side surface of the magnet housing portion 112. Further, the extension direction of the radially outer end of the second side slit 73 refers to the direction of the tangent L4 at the connecting portion (inflection point) of the inner side surface 73a and the radially outer arc surface 73c. The tangent L4 is along the extension direction of the center slit 71.
Thus, since the center slit 71, the first side slit 72, and the second side slit 73 are formed, the gap between the center slit 71 and the first side slit 72 is on the side of the outer peripheral surface 32b of the rotor core 32. The gap H2 on the permanent magnet 33 side is set larger than the gap H1.

  The permanent magnet 33 is fitted in the magnet storage unit 112. The permanent magnet 33 is formed to correspond to the shape of the magnet housing portion 112. That is, the permanent magnet 33 is formed in a substantially isosceles trapezoidal shape such that the width in the circumferential direction gradually becomes wider as the sectional shape along the radial direction goes to the inner side in the radial direction. For this reason, the permanent magnet 33 is positioned between the lower base 33a located radially inward, the upper base 33b located radially outward, and the lower base 33a and the upper base 33b in a sectional shape along the radial direction. And a pair of legs 33c.

The lower base 33 a of the permanent magnet 33 is in contact with the radially outer end 114 a of the convex portion 114 of the rotor core 32. Therefore, the flux barrier portion 113 is interposed between the lower base 33 a of the permanent magnet 33 and the ring portion 115 of the rotor core 32.
Further, the upper bottom 33 b of the permanent magnet 33 is in contact with the claw portion 118 of the rotor core 32. That is, the claws 118 function to prevent the permanent magnet 33 from coming off in the radial direction. Furthermore, the leg 33 c of the permanent magnet 33 abuts on the inner side surface of the magnet housing portion 112 of the rotor core 32.

Here, FIG. 4 shows the case where the permanent magnets 33 are magnetized in parallel orientation (indicated by arrows in FIG. 4). However, the present invention is not limited to this, and the permanent magnet 33 may be magnetized in polar anisotropic orientation.
The permanent magnet 33 configured in this way is fixed to the magnet housing portion 112 of the rotor core 32 by, for example, an adhesive. In the present embodiment, four permanent magnets 33 are arranged at equal intervals, and four rotor cores 32 are interposed between the permanent magnets 33 adjacent in the circumferential direction. Therefore, the number of magnetic poles of the rotor core 32 is four. Become.

(Speed reduction section)
Referring back to FIGS. 1 and 2, the speed reduction unit 3 includes a gear case 40 to which the motor case 5 is attached, and a worm speed reduction mechanism 41 housed in the gear case 40. The gear case 40 is made of, for example, a material having excellent heat dissipation such as aluminum die casting. The gear case 40 is formed in a box shape having an opening 40 a on one side, and has a gear accommodating portion 42 accommodating the worm reduction mechanism 41 inside. Further, an opening 43 communicating the through hole 10a of the first motor case 6 with the gear accommodating portion 42 is formed in the side wall 40b of the gear case 40 at a portion where the first motor case 6 is integrally formed. There is.

  Furthermore, on the side wall 40b of the gear case 40, three fixed brackets 54a, 54b, 54c are integrally formed. These fixing brackets 54a, 54b, 54c are for fixing the motor 1 with a reduction gear to a vehicle body (not shown) or the like. The three fixing brackets 54 a, 54 b, 54 c are arranged at substantially equal intervals in the circumferential direction so as to avoid the motor unit 2. Anti-vibration rubber 55 is attached to each of the fixing brackets 54a, 54b, 54c. The anti-vibration rubber 55 is for preventing the vibration at the time of driving the reduction gear motor 1 from being transmitted to the vehicle body (not shown).

Further, a substantially cylindrical bearing boss 49 is provided on the bottom wall 40c of the gear case 40 so as to protrude therefrom.
The bearing boss 49 is for rotatably supporting the output shaft 48 of the worm reduction mechanism 41, and a sliding bearing (not shown) is provided on the inner peripheral surface. Furthermore, an O-ring (not shown) is attached to the tip inner peripheral edge of the bearing boss 49. This prevents dust and water from entering the inside from the outside through the bearing boss 49. In addition, a plurality of ribs 52 are provided on the outer peripheral surface of the bearing boss 49. Thereby, the rigidity of the bearing boss 49 is secured.

  The worm reduction mechanism 41 housed in the gear housing portion 42 is constituted by a worm shaft 44 and a worm wheel 45 meshed with the worm shaft 44. The worm shaft 44 is disposed coaxially with the rotation shaft 31 of the motor unit 2. The worm shaft 44 is rotatably supported by bearings 46 and 47, both ends of which are provided on the gear case 40. The end portion of the worm shaft 44 on the motor portion 2 side protrudes to the opening 43 of the gear case 40 via the bearing 46. The end of the projecting worm shaft 44 and the end of the rotating shaft 31 of the motor unit 2 are joined, and the worm shaft 44 and the rotating shaft 31 are integrated. The worm shaft 44 and the rotary shaft 31 may be integrally formed by molding the worm shaft portion and the rotary shaft portion from one base material.

  The worm wheel 45 engaged with the worm shaft 44 is provided with an output shaft 48 at the radial center of the worm wheel 45. The output shaft 48 is disposed coaxially with the rotational axis direction of the worm wheel 45, and protrudes outside the gear case 40 via the bearing boss 49 of the gear case 40. At the protruding end of the output shaft 48, a spline 48a connectable to an electrical component (not shown) is formed.

  A sensor magnet (not shown) is provided at the center of the worm wheel 45 in the radial direction on the side opposite to the side where the output shaft 48 protrudes. The sensor magnet constitutes one of the rotational position detection units 60 that detects the rotational position of the worm wheel 45. The magnetic detection element 61 constituting the other of the rotational position detection unit 60 is provided in the controller unit 4 disposed opposite to the worm wheel 45 on the sensor magnet side (the opening 40 a side of the gear case 40) of the worm wheel 45. There is.

(Controller section)
The controller unit 4 which performs drive control of the motor unit 2 includes a controller substrate 62 on which the magnetic detection element 61 is mounted, and a cover 63 provided to close the opening 40 a of the gear case 40. The controller substrate 62 is disposed opposite to the sensor magnet side (the opening 40 a side of the gear case 40) of the worm wheel 45.

  The controller substrate 62 is a so-called epoxy substrate on which a plurality of conductive patterns (not shown) are formed. The controller board 62 is connected to the terminal portion of the coil 24 drawn out from the stator core 20 of the motor portion 2 and electrically connected to the terminal (all not shown) of the connector provided on the cover 63. There is. In addition to the magnetic detection element 61, a power module (not shown) including switching elements such as FETs (Field Effect Transistors) for controlling the current supplied to the coil 24 is mounted on the controller substrate 62. ing. Further, on the controller substrate 62, a capacitor (not shown) or the like for smoothing the voltage applied to the controller substrate 62 is mounted.

The cover 63 covering the controller board 62 configured in this way is formed of resin. In addition, the cover 63 is formed to bulge slightly outward. The inner surface side of the cover 63 is a controller accommodating portion 56 that accommodates the controller board 62 and the like.
Further, a connector (not shown) is integrally molded on the outer peripheral portion of the cover 63. This connector is formed to be insertable with a connector extending from an external power supply (not shown). And the controller board | substrate 62 is electrically connected to the terminal of a connector not shown. Thereby, the power of the external power supply is supplied to the controller board 62.

  Further, at the opening edge of the cover 63, a fitting portion 81 to be fitted with the end of the side wall 40b of the gear case 40 is formed to protrude. The fitting portion 81 includes two walls 81 a and 81 b along the opening edge of the cover 63. Then, the end of the side wall 40b of the gear case 40 is inserted (fitted) between the two walls 81a and 81b. Thus, the labyrinth portion 83 is formed between the gear case 40 and the cover 63. The labyrinth portion 83 prevents dust and water from entering between the gear case 40 and the cover 63. The fixing of the gear case 40 and the cover 63 is performed by fastening a bolt (not shown).

(Operation of motor with reduction gear)
Next, the operation of the reduction gear motor 1 will be described.
In the motor 1 with a reduction gear, the power supplied to the controller board 62 through a connector (not shown) is selectively supplied to each coil 24 of the motor unit 2 through a power module (not shown). Then, a predetermined magnetic flux linkage is formed on the stator 8 (the teeth 22), and a magnetic attractive force or repulsive force is generated between the magnetic flux linkage and the permanent magnet 33 of the rotor 9. Thereby, the rotor 9 rotates continuously.
When the rotor 9 rotates, the worm shaft 44 integrated with the rotation shaft 31 rotates, and the worm wheel 45 meshed with the worm shaft 44 rotates. Then, the output shaft 48 connected to the worm wheel 45 is rotated to drive a desired electrical component.

Further, the detection result of the rotational position of the worm wheel 45 detected by the magnetic detection element 61 mounted on the controller substrate 62 is output as a signal to an external device (not shown).
In the external device (not shown), the switching timing of switching elements and the like of the power module (not shown) is controlled based on the rotational position detection signal of the worm wheel 45, and the drive control of the motor unit 2 is performed. The output of the drive signal of the power module and the drive control of the motor unit 2 may be performed by the controller unit 4.

(Function of rotor, effect)
Next, the operation and effects of the rotor 9 will be described based on FIGS. 4 and 6 to 12.
Here, as shown in FIG. 4, the flux barrier portion 113 is interposed between the lower base 33 a of the permanent magnet 33 and the ring portion 115 of the rotor core 32. For this reason, it is possible to minimize the radially inward leakage flux from the permanent magnets 33 adjacent in the circumferential direction.

  Further, the permanent magnet 33 is formed in a substantially isosceles trapezoidal shape such that the width in the circumferential direction gradually becomes wider as the sectional shape along the radial direction goes to the inner side in the radial direction. For this reason, in the rotor core 32, the direction of the orientation for causing the magnetic flux of each permanent magnet 33 to converge is the outer peripheral side (the teeth 22 side of the stator 8) of the rotor core 32.

  In addition to this, the center slit 71, the first side slit 72, and the second side slit 73 are formed in the rotor core 32. Of the slits 71 to 73, the gap H2 on the permanent magnet 33 side is set larger than the gap H1 on the outer peripheral surface 32b side of the rotor core 32 in the gap between the center slit 71 and the first side slit 72. As a result, the direction of the magnetic flux in the rotor core 32 can be easily converged to the teeth 22 side. Furthermore, the magnetic flux can be concentrated at the circumferential center of the rotor core 32 per pole without bringing the permanent magnets 33 adjacent in the circumferential direction close to each other.

FIG. 6 is a view showing magnetic flux vectors of the teeth 22 and the rotor core 32. As shown in FIG.
As shown in the figure, in the rotor core 32, the magnetic flux vector of the permanent magnet 33 is directed in the d-axis direction. Here, the center slit 71 formed in the rotor core 32 is formed so as to penetrate the rotor core 32 in the axial direction and to have a cross-sectional shape along the radial direction extending in the radial direction. Further, the side slits 72 and 73 are formed so as to penetrate the rotor core 32 in the axial direction and to have a cross-sectional shape along the radial direction that is convex toward the center slit 71 side. As a result, the slits 71 to 73 are formed along the d-axis of the permanent magnet 33. Therefore, it can be confirmed that the magnetic flux of the permanent magnet 33 is formed in the rotor core 32 without blocking the magnetic path by the slits 71 to 73.

  On the other hand, the vector of the flux linkage formed by the teeth 22 of the stator 8 is directed in the q-axis direction orthogonal to the d-axis direction. Here, the slits 71 to 73 formed in the rotor core 32 extend in the direction orthogonal to the q-axis direction. That is, each of the slits 71 to 73 shuts off the magnetic path in the q-axis direction. For this reason, it can be confirmed that the interlinkage magnetic flux formed by the teeth 22 hardly passes through the rotor core 32.

For comparison, the case where the respective slits 71 to 73 are not formed in the rotor core 32 (hereinafter referred to as a conventional rotor core 132) will be described based on FIG.
FIG. 7 is a diagram showing magnetic flux vectors of the teeth 22 and the rotor core 32 in the conventional rotor core 132, and corresponds to FIG. 6 described above.
As shown in the drawing, when the slits 71 to 73 are not formed, the magnetic path in the q-axis direction is not blocked, so that the interlinkage magnetic flux formed by the teeth 22 passes through the rotor core 32. As a result, it can be confirmed that the flux vector of the permanent magnet 33 is distorted under the influence of the flux linkage.

FIG. 8 is a diagram showing the magnetic flux density of the magnetic flux formed on each of the teeth 22 and the rotor core 32. As shown in FIG. In addition, in FIG. 8, the shape of each slit 71-73 is simplified and shown.
As shown in the drawing, the side slits 72 and 73 are extended so that the radially outer arc surfaces 72 c and 73 c are closer to the center slit 71. Therefore, near the outer peripheral surface 32b of the rotor core 32, the magnetic flux of the permanent magnet 33 is formed toward the circumferential center of the rotor core 32 per one pole so as to be guided by the slits 71 to 73. As a result, it can be confirmed that the magnetic flux density at the circumferential center of the rotor core 32 per one pole is high in the vicinity of the outer peripheral surface 32b of the rotor core 32 (see C part in FIG. 8).

The case where each side slit 72, 73 is formed in parallel with the center slit 71 is demonstrated based on FIG. 9 for a comparison.
FIG. 9 is a diagram showing the magnetic flux density of the magnetic flux formed in each of the teeth 22 and the rotor core 32, corresponding to FIG. 8 described above.
As shown in the drawing, when the side slits 72 and 73 are formed in parallel with the center slit 71, the magnetic path of the magnetic flux of the permanent magnet 33 is not blocked by the slits 71 to 73. However, the magnetic flux is not concentrated at the circumferential center of the rotor core 32 per pole near the outer peripheral surface 32 b of the rotor core 32. For this reason, it can be confirmed that the magnetic flux density at the center in the circumferential direction of the rotor core 32 per one pole is lower in the vicinity of the outer peripheral surface 32b of the rotor core 32 compared to FIG. 8 described above (see D in FIG. 9).

  As described above, in the above-described embodiment, the slits 71 to 73 are formed between two permanent magnets 33 adjacent in the circumferential direction of the rotor core 32. The center slit 71 is formed so that the cross-sectional shape along the radial direction extends along the radial direction. The side slits 72 and 73 are curved so that the cross-sectional shape along the radial direction is convex toward the center slit 71 side. With this configuration, the magnetic path of the d axis, which is the magnetic path of the magnetic flux of the permanent magnet 33 provided in the rotor core 32, is not blocked by the slits 71 to 73. On the other hand, the slits 71 to 73 cut off the q-axis (axis orthogonal to the d-axis) magnetic path on the rotor core 32 side of the linkage flux formed by the stator 8. Therefore, the q-axis magnetic flux is less likely to be formed on the rotor core 32. Therefore, the influence of the flux linkage (q-axis flux) on the d-axis flux can be reduced, and sufficient motor characteristics can be exhibited in all load regions.

  Further, in the gap between the center slit 71 and the first side slit 72, the gap H2 on the permanent magnet 33 side is set larger than the gap H1 on the outer peripheral surface 32b side of the rotor core 32. And each side slit 72, 73 is extended so that circular arc surface 72c, 73c of radial direction outside may approach center slit 71. As shown in FIG. Therefore, the q-axis magnetic flux is less likely to be formed on the rotor core 32 more reliably. As a result, the influence of the linkage flux (q-axis flux) on the d-axis flux can be more reliably prevented, and sufficient motor characteristics can be exhibited in all load regions.

  Furthermore, on the outer peripheral surface 32 b of the rotor core 32, the magnetic flux of the permanent magnet 33 can be induced to the circumferential center of the rotor core 32 per one pole by the slits 71 to 73. As a result, the magnetic flux density in the circumferential center of the rotor core 32 per pole can be made as high as possible. Further, the magnetic flux density of the permanent magnet 33 can be lowered as it approaches the permanent magnet 33 (as it is separated from the circumferential center of the rotor core 32 per pole) on the outer peripheral surface 32 b of the rotor core 32. That is, since the peak width of the sine waveform of the magnetic flux density formed on the outer peripheral surface 32b of the rotor core 32 is narrowed and the saliency is improved, the torque performance of the motor unit 2 can be improved.

More specifically, it demonstrates based on FIG. 10, FIG.
In FIG. 10, the ordinate represents the flux linkage [Wb] for three phases (U phase, V phase, W phase) formed on the outer peripheral surface 32b of the rotor core 32, and the abscissa represents the rotor core 32 (rotor 9). It is a graph which shows change of linkage flux when it is considered as rotation angle [deg] of. In FIG. 11, the ordinate represents the flux linkage [Wb] for three phases (U phase, V phase, W phase) formed on the outer peripheral surface 132b of the conventional rotor core 132, and the abscissa represents the conventional rotor core 132. It is a graph which shows change of linkage flux when it is considered as rotation angle [deg] of.
As shown in FIGS. 10 and 11, the peak width of the sine waveform of the flux linkage of the rotor core 32 (see FIG. 10) of the present embodiment is narrower than that of the conventional rotor core 132 (see FIG. 11). It can confirm.

FIG. 12 is a graph showing a change in rotational speed when the vertical axis is the rotational speed [rpm] of the rotor 9 and the horizontal axis is the torque [N · m] of the motor unit 2; It compares with the rotor 9 of this embodiment. The conventional rotor in FIG. 12 refers to a rotor using the above-mentioned conventional rotor core 132.
As shown in the figure, it can be confirmed that the torque performance of the motor unit 2 is improved in the middle load region (middle rotation region; near E in FIG. 12) of the rotor 9 as compared with the conventional case.

  Further, the permanent magnet 33 is formed in a substantially isosceles trapezoidal shape such that the width in the circumferential direction gradually becomes wider as the sectional shape along the radial direction goes to the inner side in the radial direction. Therefore, in the rotor core 32, the direction of the orientation (indicated by the arrow in FIG. 4) for converging the magnetic flux of each permanent magnet 33 is the outer peripheral side of the rotor core 32. As a result, the direction of the magnetic flux in the rotor core 32 can be easily converged to the teeth 22 side. Furthermore, the magnetic flux can be concentrated in the rotor core 32 without bringing the permanent magnets 33 adjacent in the circumferential direction close to each other. Thus, the effective magnetic flux of the rotor core 32 can be increased, and the torque performance of the motor unit 2 can be improved.

(Modification)
In the above embodiment, one center slit 71, two first side slits 72, and two second side slits 73 are provided between two permanent magnets 33 adjacent in the circumferential direction of the rotor core 32. The case where a total of five slits 71 to 73 are formed has been described. However, the present invention is not limited to this, and one center slit 71 may be formed at least at the circumferential center of each pole of the rotor core 32, respectively. In addition, the side slits 71 and 72 are not limited to four in total, and only the first side slit 72 may be used, or a plurality of four or more side slits may be formed.

This will be described more specifically based on FIGS. 13 to 15.
FIG. 13 is a plan view seen from the axial direction showing a modification of the rotor core 32, and corresponds to FIG. 3 described above.
Here, FIG. 13A shows the case where only the center slits 71 are formed at the circumferential center of each pole of the rotor core 32 (the number of slits is 1 [one]). FIG. 13B shows the case where the center slit 71 and the first side slit 72 are formed (the number of slits is three). FIG. 13C shows the case where the center slit 71, the first side slit 72, and the second side slit 73 are formed (the number of slits is five).

  FIG. 14 is a graph showing changes in effective magnetic flux when the vertical axis represents the effective magnetic flux [Wb] of the rotor core 32 and the horizontal axis represents the number of slits 71 to 73 formed in the rotor core 32. FIG. 15 is a graph showing a change in the rotational speed of the rotor 9 when the vertical axis is the rotational speed [rpm] of the rotor 9 and the horizontal axis is the torque [N · m] of the motor unit 2 The number of slits formed in the rotor core 32 is compared for each.

As shown in FIGS. 13 and 14, it can be confirmed that the effective magnetic flux of the rotor core 32 does not change with the increase or decrease of the number of the slits 71 to 73.
Further, as shown in FIGS. 13 and 15, it can be confirmed that the torque performance of the motor unit 2 can be improved in proportion to the increase in the number of the slits 71 to 73.

  Moreover, in the above-mentioned embodiment, each side slit 72 and 73 demonstrated the case where it curvedly formed so that the cross-sectional shape in alignment with a radial direction might become convex toward the center slit 71 side. However, the present invention is not limited to this, and the gap between the center slit 71 and the side slits 72 and 73 is set larger than the gap on the outer peripheral surface 32 b side of the rotor core 32 near the permanent magnet 33. It should just be.

This will be more specifically described based on FIGS. 16 to 19.
FIG. 16 is a plan view seen from the axial direction showing a modified example of the rotor core 32, and corresponds to FIG. 3 described above.
Here, each side slit 72, 73 in FIG. 16 (a) is formed into a linear shape without curving a sectional shape along the radial direction, and further, between the center slit 71 and each side slit 72, 73. The gap is formed such that the gap on the immediate side of the permanent magnet 33 is larger than the gap on the outer peripheral surface 32 b side of the rotor core 32 (hereinafter referred to as five diagonal lines).
Further, the side slits 72 and 73 in FIG. 16B are curved so as to be convex toward the side opposite to the center slit 71 (hereinafter, referred to as five reverse arcs).
Furthermore, the side slits 72 and 73 in FIG. 16C are formed in parallel with the center slit 71 (hereinafter, referred to as five straights).

FIG. 17 is a graph showing a change in torque of the motor unit 2 when the vertical axis represents the torque [N · m] of the motor unit 2 and the horizontal axis represents the rotation angle [deg] of the rotor 9. The rotor core 132 (see FIG. 7), the rotor core 32 of the present embodiment (see FIG. 4), the five diagonal rotor cores 32, the five reverse circular arc rotor cores 32, and the five straight rotor cores 32 are compared.
In FIG. 18, the scale of the horizontal axis in FIG. 17 is reduced, and the rotor core 32 (see FIG. 4) of this embodiment, five diagonal rotor cores 32, five reverse circular arc rotor cores 32, and five straight rotor cores 32 are used. I'm comparing.

As shown in FIGS. 16 (a) to 16 (c) and FIG. 17, it can be confirmed that torque ripple can be reduced when the respective slits 71 to 73 are formed in the rotor core 32 as compared with the conventional case.
Here, as shown in FIG. 18, in the case of five straight rotor cores 32, the rotor core 32 of this embodiment (see FIG. 4), five oblique rotor cores 32, and five reverse arcs of rotor cores 32 are compared. Then, it can be confirmed that the torque ripple (see F part in FIG. 18) of the predetermined rotation angle slightly increases.

19 shows the torques of the conventional rotor core 132 (see FIG. 7), the rotor core 32 of the present embodiment (see FIG. 4), the five diagonal rotor cores 32, the five reverse circular arc rotor cores 32, and the five straight rotor cores 32. It is the graph which compared the ripple rate [%].
As shown in the figure, the torque ripple rate is particularly reduced when the shape of each side slit 72, 73 formed in the rotor core 32 is five diagonally and in the case of a reverse arc in addition to the present embodiment. You can confirm that.
As described above, as is apparent from FIGS. 17 to 19, it is desirable that the side slits 72 and 73 formed in the rotor core 32 be five in the oblique direction and a reverse arc in addition to the present embodiment.

  Moreover, in the above-mentioned embodiment, the case where the radial direction outer side end of the center slit 71 was extended to the front side of the outer peripheral surface 32b of the rotor core 32 was demonstrated. Further, the case where the radially outer ends of the side slits 72 and 73 extend to the front of the outer peripheral surface 32 b of the rotor core 32 has been described. However, the present invention is not limited to this, and as shown in FIG. 20, the radial outer end of the center slit 71 and the radial outer ends of the side slits 72 and 73 reach the outer peripheral surface 32 b of the rotor core 32 respectively. You may form. Then, the slits 71 to 73 may be formed to open on the side of the outer peripheral surface 32 b.

  Furthermore, in the above-described embodiment, the permanent magnet 33 is formed in a substantially isosceles trapezoidal shape so that the width in the circumferential direction gradually increases as the cross-sectional shape along the radial direction goes inward in the radial direction. did. However, the present invention is not limited to this, and as shown in FIG. 21, the permanent magnet 33 may be formed so that the cross-sectional shape along the radial direction is substantially rectangular along the radial direction.

Moreover, the above-mentioned embodiment demonstrated the case where the rotor core 32 was formed in the column shape which makes the rotating shaft 31 the axial center C1. However, the present invention is not limited to this, and as shown in FIG. 22, the arc center C2 of the outer peripheral surface 32b of the rotor core 32 may be eccentric from the axial center C1 of the rotation shaft 31.
More specifically, between the two permanent magnets 33 adjacent in the circumferential direction, the arc center C2 of the outer circumferential surface 32b of the rotor core 32 is a straight line along the radial direction passing through the circumferential center of the rotor core 32 and rotates It is set closer to the outer peripheral surface 32 b of the corresponding rotor core 32 than the shaft 31. Therefore, the radius of curvature of the outer peripheral surface 32 b of the rotor core 32 is set shorter than the radius of the rotor core 32.

  By forming the rotor core 32 in this manner, the minute gap S1 between the outer peripheral surface 32b of the rotor core 32 and the inner peripheral surface of the flange portion 102 of the teeth 22 extends circumferentially from the circumferential center of the rotor core 32 per pole. It becomes larger gradually as you move away. For this reason, it can prevent that the influence of the magnetic flux of the permanent magnet 33 of the rotor core 32 with respect to the teeth 22 changes rapidly. Thus, the cogging torque of the motor unit 2 can be reduced.

In addition, the present invention is not limited to the above-described embodiment, and includes the above-described embodiment with various modifications added thereto, without departing from the spirit of the present invention.
For example, in the above-mentioned embodiment, the case where motor 1 with a reduction gear serves as a drive source of an electric component (for example, a power window, a sunroof, an electric sheet etc.) carried in vehicles was explained. However, the invention is not limited to this, and the speed reducer motor 1 can be used in various applications.

  Moreover, in the above-mentioned embodiment, the case where four magnet accommodating parts 112 were formed in the rotor core 32, and four permanent magnets 33 were provided in the rotor core 32 was demonstrated. However, the present invention is not limited to this, and the number of magnet housings 112 of the rotor core 32 and the number of permanent magnets 33 can be set arbitrarily.

DESCRIPTION OF SYMBOLS 1 ... motor with reduction gear, 2 ... motor part (electric motor), 8 ... stator, 9 ... rotor, 22 ... teeth, 24 ... coil, 31 ... rotating shaft (shaft) 32 ... rotor core, 32b ... outer peripheral surface, 33 ... Permanent magnet, 71 ... Center slit, 72 ... First side slit (side slit), 73 ... Second side slit (side slit), C1 ... Axis (rotational axis)

Claims (7)

A shaft that rotates about an axis of rotation;
A rotor core fixed to the shaft and radially centered on the axis of rotation;
A plurality of permanent magnets provided in the rotor core and arranged radially such that a cross-sectional shape orthogonal to the rotation axis is along the radial direction of the rotor core;
Equipped with
A center slit extending in a radial direction at a cross-sectional shape perpendicular to the rotation axis is formed at all in the center between two permanent magnets adjacent in the circumferential direction of the rotor core. Rotor. In the rotor core, a plurality of side slits are formed such that the magnetic flux density of the outer peripheral surface formed by the permanent magnets increases toward the center between the two adjacent permanent magnets in the circumferential direction. The rotor according to claim 1, characterized in that: The plurality of side slits are formed such that a cross-sectional shape orthogonal to the rotation axis extends from the immediate vicinity of the circumferential side surface of the permanent magnet toward the outer peripheral surface of the rotor core.
The clearance between the center slit and the side slit is set to be larger than the clearance on the outer peripheral surface side of the rotor core, in the clearance on the immediate side of the permanent magnet. Rotor. The rotor according to claim 2 or 3, wherein the side slit has a curved cross-sectional shape perpendicular to the rotation axis. The side slits are curved so that a cross-sectional shape orthogonal to the rotation axis is convex toward the center slit.
In the cross-sectional shape of the side slit,
The extension direction of the nearest side of the circumferential side surface of the permanent magnet is along the direction orthogonal to the circumferential side surface of the permanent magnet,
The rotor according to any one of claims 2 to 4, wherein the extension direction of the outer peripheral surface side of the rotor core is along the extension direction of the center slit. 5. The permanent magnet according to claim 1, wherein the permanent magnet is formed in a trapezoidal shape such that the width in the circumferential direction gradually increases as the cross-sectional shape orthogonal to the rotation axis goes radially inward. The rotor according to any one of the preceding claims. A rotor according to any one of claims 1 to 5;
An electric motor comprising: a stator formed in an annular shape so as to surround the outer periphery of the rotor, and having a plurality of teeth around which a coil for generating a magnetic field is wound.