Motor device

Abstract

To enable a rotor to be pressed in an axial direction by a magnetic attraction force, and enable stable sensing to be performed while suppressing an increase in an inertia mass.SOLUTION: An axially central part of a ring magnet 43 is offset from an axially central part of a stator core 31 in a direction opposite to an abutting direction of an abutting member 44 against a first ball bearing 23. Therefore, by supplying a drive current to a coil 34 to drive an electric motor part 20, it is possible to generate a magnetic attraction force MF that attempts to move a rotor 40 to the other side in an axial direction. Due to an action of the magnetic attractive force MF, it is possible to prevent an axial position of the rotor 40 from fluttering and shifting, and consequently, it is possible to keep a separation distance between the ring magnet 43 and a total of three Hall elements Hv and Hw (only two are shown in Fig.9) in an axial direction of a rotating shaft 41 constant, and it is possible to perform stable sensing while suppressing an increase in inertia mass.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a motor device including a stator and a rotor. [Background technology]

[0002] For example, Patent Document 1 describes a motor including a motor shaft, a sensor magnet that is movable in the axial direction relative to the motor shaft, and a sensor board that faces the sensor magnet in the axial direction of the motor shaft. The sensor magnet is pressed toward the sensor board in the axial direction of the motor shaft by the spring force of a spring. This makes it possible to automatically adjust the gap between the sensor magnet and the magnetic detection element of the sensor board, thereby stabilizing sensing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-127709 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in Patent Document 1, a sensor magnet with a larger diameter than the motor shaft is pressed toward the sensor board by the spring force of a spring, which requires a spring that generates a relatively large spring force, which increases the weight of the rotor and the inertial mass, potentially resulting in a decrease in responsiveness.

[0005] An object of the present invention is to provide a motor device that can press a rotor in the axial direction by magnetic attraction force and can perform stable sensing while suppressing an increase in inertial mass. [Means for solving the problem]

[0006] One aspect of the motor device is a motor device comprising a stator and a rotor, wherein the stator has a stator core fixed to the radially inner side of a motor case and coils wound around teeth provided on the stator core, and the rotor comprises a rotating shaft rotatably supported by bearings fixed to the motor case, a magnet integrally provided on the rotating shaft, and a butting member fixed to the rotating shaft and abutting against the bearing from one axial side of the rotating shaft toward the other axial side of the rotating shaft, wherein the axial center of the magnet is shifted in the opposite direction to the abutting direction of the abutting member against the bearing relative to the axial center of the stator core. [Effects of the Invention]

[0007] According to the present invention, it is possible to realize a motor device that can press the rotor in the axial direction by magnetic attraction force and can perform stable sensing while suppressing an increase in inertial mass. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a seat motor mounted on a vehicle. [Figure 2] 2 is a cross-sectional view taken along the axial direction of the rotation shaft of the seat motor of FIG. 1. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is an enlarged cross-sectional view showing the periphery of a first ball bearing. [Figure 5] FIG. 4 is an enlarged cross-sectional view showing the periphery of a second ball bearing. [Figure 6] FIG. 2 is a perspective view of the inside of the electric motor unit as viewed from the cover member side. [Figure 7] FIG. 4 is a perspective view showing the inside of the cover member. [Figure 8] FIG. 2 is an exploded perspective view showing a rotor and first and second planetary gear reducers. [Figure 9] FIG. 4 is a cross-sectional view of an electric motor for explaining the action of magnetic attraction force. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0010] Figure 1 is a perspective view showing a seat motor mounted on a vehicle, Figure 2 is a cross-sectional view along the axial direction of the rotating shaft of the seat motor in Figure 1, Figure 3 is a cross-sectional view along line AA in Figure 2, Figure 4 is an enlarged cross-sectional view showing the periphery of the first ball bearing, Figure 5 is an enlarged cross-sectional view showing the periphery of the second ball bearing, Figure 6 is a perspective view of the inside of the electric motor unit seen from the cover member side, Figure 7 is a perspective view showing the inside of the cover member, Figure 8 is an exploded perspective view showing the rotor and first and second planetary gear reducers, and Figure 9 is a cross-sectional view of the electric motor unit explaining the action of magnetic attraction force.

[0011] <Outline of the electric seat> The seat motor 10 shown in Fig. 1 is a drive source built into an electric seat installed in a vehicle such as an automobile. Specifically, the seat motor 10 drives a reclining mechanism for the backrest, a sliding mechanism that moves the electric seat back and forth, and a lifting mechanism that raises and lowers the seat. This allows the driver to adjust the posture and position of the electric seat to their preferred driving position by operating an operation switch located, for example, on the side of the electric seat.

[0012] The seat motor 10 includes a connector CN, which is electrically connected to an in-vehicle controller CR. Between the electric motor section 20 constituting the seat motor 10 and the connector CN are a power supply line PL that supplies a drive current to the electric motor section 20 and a sensor line SW that sends a sensor signal indicating the rotation state of the electric motor section 20 to the in-vehicle controller CR.

[0013] This allows the in-vehicle controller CR to store multiple driving positions (electric seat positions) corresponding to drivers of different physiques, and the driver can then call up the stored driving position according to his or her preference.

[0014] <Seat motor> 1 to 7, the seat motor 10 includes an electric motor section 20 and a speed reduction mechanism section 50. The electric motor section 20 and the speed reduction mechanism section 50 are arranged coaxially, and the overall shape of the seat motor 10 is a short, rectangular, and generally rod-like shape.

[0015] The seat motor 10 corresponds to the motor device in the present invention.

[0016] <Electric motor section> The electric motor unit 20 includes a casing 21. The casing 21 is formed into a cylindrical shape with a bottom by deep drawing a steel plate, and its cross section along a direction perpendicular to the longitudinal direction is substantially square.

[0017] 2 and 4, a bottom wall portion 22 is provided on the side of the reduction mechanism portion 50 in the longitudinal direction of the casing 21 (on the left side in the drawings). A bearing support cylinder 22a is provided integrally with the center of the bottom wall portion 22, and an outer ring 23a of a first ball bearing 23 is fixed to the bearing support cylinder 22a by press-fitting.

[0018] The bearing support cylinder 22a corresponds to the bearing fixing portion in this invention.

[0019] Also, approximately two-thirds of the axial portion of first ball bearing 23 on the electric motor unit 20 side (right side in the figure) is press-fitted into bearing support cylinder 22a. Furthermore, approximately one-third of the axial portion of first ball bearing 23 on the speed reduction mechanism unit 50 side is exposed (protrudes) from bearing support cylinder 22a toward speed reduction mechanism unit 50.

[0020] Here, first ball bearing 23 rotatably supports the speed reduction mechanism 50 side of rotating shaft 41 in the axial direction, and inner ring 23b of first ball bearing 23 is attached to the speed reduction mechanism 50 side of rotating shaft 41. Specifically, inner ring 23b of first ball bearing 23 is attached to rotating shaft 41 so as to be movable only in the axial direction of said rotating shaft 41.

[0021] 4, a plurality of steel balls (rolling elements) 23c are arranged between outer ring 23a arranged on the radially outer side and inner ring 23b arranged on the radially inner side in the radial direction of first ball bearing 23. This allows outer ring 23a and inner ring 23b to rotate smoothly relative to each other via steel balls 23c.

[0022] Here, in the axial direction of the rotating shaft 41, the side where the connector CN of the seat motor 10 is arranged (right side in Figure 2) is defined as the "one axial side," and the side where the reduction mechanism part 50 of the seat motor 10 is arranged (left side in Figure 2) is defined as the "other axial side."

[0023] A pair of screw holes 22b (only one is shown in FIGS. 2 and 4) are provided in the bottom wall portion 22. Specifically, the pair of screw holes 22b are arranged opposite each other with the bearing support cylinder 22a at the center. A fixing screw S for fixing the speed reduction mechanism portion 50 to the electric motor portion 20 is screwed into each screw hole 22b.

[0024] 2 and 5, an opening 24 is provided on one axial side of the casing 21, i.e., on the side opposite to the bottom wall portion 22. The stator 30 and the rotor 40 are fitted inside the casing 21 through this opening 24.

[0025] A cover member 25 made of a resin material such as plastic is attached to the opening 24. The cover member 25 closes the opening 24, thereby preventing dust and the like from entering the inside of the casing 21. As shown in FIG. 7, a pair of engagement recesses 25a are provided on the outer periphery of the cover member 25. As shown in FIG. 6, two of the four engagement claws 21a of the casing 21 are engaged with these engagement recesses 25a. Therefore, the cover member 25 is prevented from coming off the casing 21 without any rattle.

[0026] The casing 21 and the cover member 25 correspond to the motor case in the present invention.

[0027] As shown in FIG. 5, a bearing support hole 25b is provided in the center of the cover member 25, and an outer ring 26a of a second ball bearing 26 is press-fitted into the bearing support hole 25b.

[0028] The bearing support hole 25b corresponds to the bearing fixing portion in this invention.

[0029] The second ball bearing 26 rotatably supports one axial side of the rotating shaft 41, and an inner ring 26b of the second ball bearing 26 is attached to one axial side of the rotating shaft 41. Specifically, the inner ring 26b of the second ball bearing 26 is attached to the rotating shaft 41 so as to be movable only in the axial direction of the rotating shaft 41.

[0030] Here, in the radial direction of the second ball bearing 26, a plurality of steel balls (rolling elements) 26c are arranged between an outer ring 26a arranged on the radially outer side and an inner ring 26b arranged on the radially inner side. This allows the outer ring 26a and the inner ring 26b to smoothly rotate relative to each other via the steel balls 26c. Note that the first ball bearing 23 and the second ball bearing 26 are both general-purpose products, and the same parts are used. This simplifies parts management and improves assembly.

[0031] Furthermore, a conductive member holding plate 27 is attached to one axial side of the cover member 25. Three conductive members Cu, Cv, and Cw (see FIG. 7) corresponding to the U-phase, V-phase, and W-phase (three phases) are attached to the cover member 25 side of the conductive member holding plate 27. Furthermore, the power line PL and the sensor line SW are drawn out to the connector CN side (right side in the figure) of the conductive member holding plate 27.

[0032] Three power supply lines PL corresponding to the U phase, V phase, and W phase are electrically connected to one ends of the three conductive members Cu, Cv, and Cw, respectively. Meanwhile, the other ends of the three conductive members Cu, Cv, and Cw are electrically connected to coils 34 corresponding to the U phase, V phase, and W phase, respectively, via connection terminals Tu, Tv, and Tw shown in FIG.

[0033] 2, 5, and 7, a sensor board 29 is fixed to the other axial side of the cover member 25 with screws SC. A through-hole 29a, through which one axial side of the rotation shaft 41 passes, is provided in the center of the sensor board 29, and a total of three Hall elements Hu, Hv, and Hw corresponding to the U phase, V phase, and W phase are arranged near the through-hole 29a so as to surround the through-hole 29a. In this way, the total of three Hall elements Hu, Hv, and Hw are provided to the cover member 25 via the sensor board 29 and are arranged at equal intervals (120-degree intervals) around the periphery of the through-hole 29a.

[0034] Here, the three Hall elements Hu, Hv, and Hw in total are rotation sensors that detect the rotation state of the rotor 40 (rotating shaft 41), and correspond to the magnetic sensor in the present invention.

[0035] These Hall elements Hu, Hv, and Hw face one axial end of ring magnet 43 in the axial direction of rotating shaft 41. As a result, each of Hall elements Hu, Hv, and Hw generates a square wave signal at a respective timing in response to a change in magnetic pole accompanying the rotation of ring magnet 43 (rotating shaft 41).

[0036] The square wave signals generated by the three Hall elements Hu, Hv, and Hw are sent to the in-vehicle controller CR (see FIG. 1) via five sensor lines SW (see FIG. 7) electrically connected to the sensor board 29. This allows the in-vehicle controller CR to grasp the rotation state of the rotor 40 and control the rotation direction and rotation speed of the rotor 40, as well as the stopping position of the rotor 40.

[0037] 2 to 5, a stator 30 is fixed to the radially inner side of the casing 21. Specifically, the stator 30 includes a stator core 31 formed of a ferromagnetic material in a substantially cylindrical shape, and the stator core 31 is fixed to the radially inner side of the casing 21.

[0038] Additionally, a plurality of teeth 32 projecting toward the rotor 40 are integrally formed on the radially inner side of the stator core 31. The number of teeth 32 is equal to the number of slots in the stator core 31, which is six in this embodiment. Of course, the number of teeth 32 can be set arbitrarily in accordance with the specifications of the electric motor unit 20.

[0039] An insulator 33 made of a resin material such as plastic is attached to each of the six teeth 32. A coil 34 is wound around each tooth 32 via the insulator 33. Coils 34 of the same phase are wound around each pair of teeth 32 that are arranged opposite each other with the rotor 40 at the center. That is, the coils 34 are arranged at equal intervals (60-degree intervals) around the circumferential direction of the stator 30 in the order of U-phase, V-phase, W-phase, U-phase, V-phase, and W-phase.

[0040] 3, a total of four press-fit corners 31a are provided on the outer periphery of the stator core 31. Specifically, these press-fit corners 31a are arranged at equal intervals (90-degree intervals) in the circumferential direction of the stator core 31. These press-fit corners 31a are fixed by press-fitting into arc-shaped corners 21b that form part of the inner wall of the casing 21.

[0041] This reduces the contact area of ​​the stator core 31 with the casing 21, preventing the press-fit load of the stator core 31 onto the casing 21 from becoming too large, while ensuring sufficient fixing strength between them. The stator 30, including the stator core 31, teeth 32, insulators 33, and coils 34, is assembled through the opening 24 of the casing 21 using an automatic assembly machine (not shown). Therefore, the stator core 31 is positioned at a specified position with high precision in the axial direction of the casing 21.

[0042] Here, two coils 34 each corresponding to the U phase, V phase, and W phase are electrically connected to connection terminals Tu, Tv, and Tw corresponding to the U phase, V phase, and W phase, respectively, via crossover wires WT (see FIG. 6).

[0043] <Rotor> 2 to 5, a rotor 40 is rotatably mounted on the radially inner side of the stator 30 via a small gap (air gap). The rotor 40 has a rotating shaft 41 made of a stepped round steel bar. Specifically, a small diameter portion 41a is integrally formed on the other axial side of the rotating shaft 41 (the left side in FIG. 2), and a first sun gear 71 that forms a first planetary gear reducer 70 of the reduction mechanism 50 is fixed to the small diameter portion 41a.

[0044] One axial side of the rotating shaft 41 (the right side in FIG. 2) is rotatably supported by the second ball bearing 26, and the other axial side of the rotating shaft 41 is rotatably supported by the first ball bearing 23. In other words, the rotating shaft 41 is rotatably supported by the first ball bearing 23 and the second ball bearing 26 fixed to the casing 21 and the cover member 25.

[0045] The first ball bearing 23 corresponds to the bearing and the rolling bearing in the present invention, and the second ball bearing 26 corresponds to the other bearing and the rolling bearing in the present invention.

[0046] Furthermore, a rotor core 42 made of a plurality of laminated steel plates made of a ferromagnetic material is attached to the outer periphery of the rotating shaft 41. Specifically, by press-fitting the rotating shaft 41 into a fixing hole 42a of the rotor core 42, the rotor core 42 is firmly fixed to the rotating shaft 41 at a specified position in the axial direction.

[0047] Furthermore, a ring magnet 43 is fixed to the outer periphery of the rotor core 42 via an adhesive (not shown). The ring magnet 43 is, for example, a neodymium magnet and is formed in a substantially cylindrical shape. The ring magnet 43 is magnetized so that south poles, north poles, south poles, and north poles (a total of four poles) are arranged alternately in the circumferential direction. In other words, the electric motor unit 20 is a four-pole, six-slot brushless motor. Of course, the number of poles of the ring magnet 43 can be set arbitrarily according to the specifications of the electric motor unit 20.

[0048] The ring magnet 43 is integrally provided on the rotary shaft 41 via the rotor core 42, and corresponds to the magnet in the present invention.

[0049] As shown in Fig. 4, the other axial end of ring magnet 43 abuts against abutting member 44. On the other hand, as shown in Fig. 5, one axial end of ring magnet 43 abuts against opposing member 45. As a result, ring magnet 43 is positioned accurately at a specified position in the axial direction of rotating shaft 41 by abutting member 44 and opposing member 45 fixed to rotating shaft 41.

[0050] 2 and 4, abutment member 44 is disposed on the other axial side of rotating shaft 41, i.e., on the side of small diameter portion 41a. Abutment member 44 is made of PPS resin (polyphenylene sulfide) containing glass fiber, and faces first ball bearing 23, rotor core 42, and ring magnet 43 in the axial direction of rotating shaft 41.

[0051] The abutment member 44 has a cylindrical fixing portion 44a that is fixed to the rotating shaft 41 by press-fitting. Furthermore, an annular abutment portion 44b that abuts against the inner ring 23b of the first ball bearing 23 in the axial direction of the rotating shaft 41 is provided on the other axial side of the cylindrical fixing portion 44a. In this way, the abutment member 44 is fixed to the rotating shaft 41, and abuts against the first ball bearing 23 from one axial side of the rotating shaft 41 to the other axial side of the rotating shaft 41. Therefore, the axial position of the rotating shaft 41 to which the abutment member 44 is fixed is determined by the first ball bearing 23.

[0052] The abutting member 44 also includes an annular flat plate portion 44c. The annular flat plate portion 44c has a larger diameter than the cylindrical fixing portion 44a and is formed in a generally plate-like shape. The annular flat plate portion 44c is integrally provided on one axial side of the cylindrical fixing portion 44a in the axial direction of the rotating shaft 41.

[0053] The other axial end of rotor core 42 and the other axial end of ring magnet 43 are respectively abutted against one axial side of annular flat plate portion 44c. As a result, the axial positions of rotor core 42 and ring magnet 43 are determined by first ball bearing 23 via abutment member 44.

[0054] 2 and 5, an opposing member 45 is fixed to one axial side of the rotating shaft 41, i.e., the side opposite to the small diameter portion 41a. The opposing member 45 is also made of PPS resin containing glass fiber, like the abutting member 44. The opposing member 45 is provided between the second ball bearing 26 and the ring magnet 43 in the axial direction of the rotating shaft 41, and faces the second ball bearing 26, the rotor core 42, and the ring magnet 43 in the axial direction of the rotating shaft 41.

[0055] The opposing member 45 has a cylindrical fixing portion 45a that is fixed to the rotating shaft 41 by press-fitting. An annular spring support portion 45b that supports the other axial side of an anti-rattle spring SP made of a coil spring is provided on one axial side of the cylindrical fixing portion 45a. One axial side of the anti-rattle spring SP is supported by the inner ring 26b of the second ball bearing 26.

[0056] The anti-rattle spring SP is disposed between the spring support portion 45b and the inner ring 26b with an initial load applied thereto. That is, the anti-rattle spring SP is disposed between the second ball bearing 26 and the opposing member 45 in the axial direction of the rotating shaft 41 with a compressive load applied thereto. As a result, the rotor 40 and the anti-rattle spring SP are disposed between the inner ring 23b of the first ball bearing 23 and the inner ring 26b of the second ball bearing 26 so as to be stretched against each other.

[0057] The rattle suppression spring SP corresponds to the coil spring in the present invention.

[0058] This prevents the inner rings 23b, 26b of the first and second ball bearings 23, 26 from rattling in the axial direction relative to the outer rings 23a, 26a, respectively. In this manner, the spring force of the rattle-suppressing spring SP prevents the first and second ball bearings 23, 26 from rattling in the axial direction, which in turn effectively prevents mechanical noise from being generated when the rotor 40 rotates.

[0059] The opposing member 45 also includes an annular flat plate portion 45c. The annular flat plate portion 45c has a larger diameter than the cylindrical fixing portion 45a and is formed in a generally plate-like shape. The annular flat plate portion 45c is integrally provided on the other axial side of the cylindrical fixing portion 45a in the axial direction of the rotating shaft 41.

[0060] One axial end of the ring magnet 43 abuts against the other axial side of the annular flat plate portion 45c. This prevents the ring magnet 43 from rattling in the axial direction of the rotating shaft 41 between the abutting member 44 and the opposing member 45, and the ring magnet 43 is accurately positioned at a specified position in the axial direction of the rotating shaft 41.

[0061] <Deceleration mechanism section> 2 and 4, the speed reduction mechanism 50 includes a reducer case 51. The reducer case 51 is formed into a cylindrical shape with a bottom by deep drawing a steel plate, and the cross section along the direction perpendicular to the longitudinal direction thereof is substantially square.

[0062] An annular bottom wall 52 is provided on one axial side of the reducer case 51, which abuts against the bottom wall portion 22 of the casing 21 in the axial direction of the rotating shaft 41. A fitting cylinder 52a into which the bearing support cylinder 22a of the casing 21 is fitted is integrally provided in the center of the annular bottom wall 52. As a result, the reducer case 51 is arranged coaxially with the casing 21.

[0063] The annular bottom wall 52 is provided with a pair of screw insertion holes (not shown) through which fixing screws S for fixing the reduction mechanism unit 50 to the electric motor unit 20 are inserted. Specifically, the pair of screw insertion holes are opposed to a pair of screw holes 22b provided in the bottom wall portion 22 of the casing 21 in the axial direction of the rotating shaft 41, respectively.

[0064] An opening 53 is provided on the other axial side of the reducer case 51, i.e., on the opposite side to the annular bottom wall 52. The planetary gear reducer 60 is fitted inside the reducer case 51 through this opening 53. An engagement shoulder SH (see FIG. 1) is provided on the other axial side of the planetary gear reducer 60, and an engagement claw 51a (see FIG. 1) of the reducer case 51 engages with this engagement shoulder SH. This prevents the planetary gear reducer 60 from coming loose from the reducer case 51.

[0065] The planetary gear reducer 60 is formed in a generally box shape and includes a gear box 61 with an internal gear 61a formed on its radially inner side. The gear box 61 is made of a resin material such as plastic and includes a large-diameter portion 61b and a small-diameter portion 61c. Specifically, the large-diameter portion 61b is disposed on one axial side of the gear box 61, and the small-diameter portion 61c is disposed on the other axial side of the gear box 61. The internal gear 61a is provided across the entire axial area of ​​the large-diameter portion 61b.

[0066] On the other hand, a third ball bearing 62 having an outer ring 62a, an inner ring 62b, and steel balls 62c is housed inside the small diameter portion 61c. Specifically, the outer ring 62a of the third ball bearing 62 is fixed by press fitting inside the small diameter portion 61c, and the inner ring 62b of the third ball bearing 62 rotatably supports an output shaft 84 that forms the second planetary gear reducer 80.

[0067] An annular closing member 63 that closes a box opening 61d of the gear box 61 is provided on one axial side of the gear box 61. The closing member 63 is fixed to the box opening 61d by press fitting. A through hole 63a is provided in the center of the closing member 63, and the through hole 63a is fitted into approximately one-third of the first ball bearing 23 on one axial side.

[0068] This causes the axis of the closing member 63 (planetary gear reducer 60) and the axis of the first ball bearing 23 to coincide with each other without any misalignment. Therefore, the driving force of the rotating shaft 41, which is rotatably supported by the first ball bearing 23, can be efficiently transmitted to the planetary gear reducer 60. Inside the gear box 61 and the closing member 63, there are housed a first planetary gear reducer 70 arranged on the input side (the electric motor unit 20 side), and a second planetary gear reducer 80 arranged on the output side (the side where a reclining mechanism, etc. is provided).

[0069] Specifically, the first planetary gear reducer 70 and the second planetary gear reducer 80 are arranged in the axial direction of the rotating shaft 41 so as to be able to transmit power to each other, and the planetary gear reducer 60 performs two-stage reduction. This allows the diameter of the planetary gear reducer 60 to be reduced.

[0070] <First planetary gear reducer> 4 and 8, first planetary gear reducer 70 has a first sun gear 71 that is attached to small diameter portion 41a of rotating shaft 41 and functions as an input portion of first planetary gear reducer 70. First sun gear 71 is rotated by rotating shaft 41, is press-fitted and fixed to small diameter portion 41a, and is precisely positioned coaxially with small diameter portion 41a.

[0071] First sun gear 71 corresponds to the drive gear in the present invention, and planetary gear reducer 60 (first and second planetary gear reducers 70, 80) driven by first sun gear 71 corresponds to the driven object in the present invention.

[0072] The first planetary gear reducer 70 also includes three first planetary gears 72 (only two are shown in FIG. 8 ) that are meshed with both the internal gear 61 a provided in the gearbox 61 and the first sun gear 71 and roll around the first sun gear 71. These first planetary gears 72 are each rotatably supported by a first carrier 73 that forms the first planetary gear reducer 70. Specifically, the three first planetary gears 72 are arranged at equal intervals (at 120-degree intervals) around the circumferential direction of the first carrier 73.

[0073] One axial side of each first planetary gear 72 rotatably abuts against the blocking member 63, and the other axial side of each first planetary gear 72 rotatably abuts against the first carrier 73. Therefore, the three first planetary gears 72 can rotate smoothly and do not rattle in the axial direction of the rotary shaft 41.

[0074] Here, abutment portion 44b of abutment member 44 fixed to rotating shaft 41 abuts against inner ring 23b of first ball bearing 23, so first sun gear 71 is positioned with high precision at a specified position in the axial direction of rotating shaft 41. Therefore, first sun gear 71 does not abut against first carrier 73, and is properly meshed with first planetary gear 72.

[0075] The planetary gear reducer 60 is centered by the first ball bearing 23 via the blocking member 63. Furthermore, the rotating shaft 41 of the rotor 40 is also centered by the first ball bearing 23. As a result, the axis of the planetary gear reducer 60 and the axis of the rotor 40 including the first sun gear 71 are aligned with high precision using the first ball bearing 23 as a reference. Therefore, like the rotor 40, the planetary gear reducer 60 can rotate stably at high speed without generating large mechanical noise.

[0076] Furthermore, a second sun gear 81 is integrally provided on the other axial side of first carrier 73. The second sun gear 81 functions as an output portion of first planetary gear reducer 70 and also functions as an input portion of second planetary gear reducer 80. Second sun gear 81 is hollow, and is disposed at the axis of first carrier 73.

[0077] <Second planetary gear reducer> As shown in FIGS. 4 and 8, the second planetary gear reducer 80 has a second sun gear 81 that is provided integrally with the first carrier 73 of the first planetary gear reducer 70.

[0078] The second planetary gear reducer 80 also includes three second planetary gears 82 (only two are shown in FIG. 8 ) that are meshed with both the internal gear 61 a provided in the gearbox 61 and the second sun gear 81 and roll around the second sun gear 81. These second planetary gears 82 are each rotatably supported by a second carrier 83 that forms the second planetary gear reducer 80. Specifically, the three second planetary gears 82 are arranged at equal intervals (at 120-degree intervals) around the circumferential direction of the second carrier 83.

[0079] One axial side of the second planetary gears 82 rotatably abuts against the first carrier 73 via the seat member ST, and the other axial side of the second planetary gears 82 rotatably abuts against the second carrier 83. Therefore, all three second planetary gears 82 can rotate smoothly and do not rattle in the axial direction of the rotary shaft 41.

[0080] An output shaft 84 that functions as an output portion of the second planetary gear reducer 80 is integrally provided on the other axial side of the second carrier 83. Here, the output shaft 84 is rotatably supported by the inner ring 62b of the third ball bearing 62, and is connected to a reclining mechanism or the like (not shown) so as to be capable of transmitting power.

[0081] Here, a pin hole 83a is formed in the axis of second carrier 83, and the other axial side of a support pin PN is attached to this pin hole 83a. Also, one axial side of the support pin PN is attached to a hollow portion 81a formed in second sun gear 81. Note that the support pin PN aligns the axis of first carrier 73 (second sun gear 81) with the axis of second carrier 83 (output shaft 84) and supports them so that they can rotate relative to each other.

[0082] In this way, the planetary gear reducer 60 performs two-stage reduction using the first and second planetary gear reducers 70, 80, reducing the rotational speed of the rotor 40 (rotating shaft 41), which rotates at high speed, to a predetermined rotational speed, and the reduced, high-torque rotational force is output from the output shaft 84 to a reclining mechanism or the like (not shown).

[0083] <Magnetic attraction force> As shown in FIG. 9, in the electric motor section 20 according to this embodiment, the length dimension L1 of the stator core 31 in the axial direction of the rotary shaft 41 is shorter than the length dimension L2 of the ring magnet 43 (L1 <L2)。

[0084] Furthermore, the axial center of ring magnet 43 is shifted, relative to the axial center of stator core 31, to the side opposite the abutting direction of abutting member 44 against first ball bearing 23, that is, to one axial side of rotating shaft 41. Specifically, in the axial direction of rotating shaft 41, the position of magnet center MC at the axial center of ring magnet 43 is shifted to one axial side (right side in the drawing) by an amount of deviation AD relative to the position of core center CC at the axial center of stator core 31.

[0085] The length L of the electric motor section 20 is about 80.0 mm, and the deviation AD is about 1.0 mm.

[0086] In order to improve the rotational efficiency of the rotor, the core center of the stator core and the magnet center of the ring magnet are usually aligned in the axial direction of the rotating shaft when designing a motor device. In contrast, in the electric motor section 20 according to this embodiment, as shown in Fig. 9, they are intentionally offset (by design) by an offset amount AD (approximately 1.0 mm).

[0087] 9, in the assembled state of electric motor section 20, the entire longitudinal area of ​​stator core 31 is disposed within the longitudinal area of ​​ring magnet 43. Therefore, the rotation efficiency of rotor 40 relative to stator 30 is hardly reduced.

[0088] When a drive current is supplied to the three-phase coils 34 under the control of the on-board controller CR (see FIG. 1) to drive the electric motor unit 20, a magnetic attraction force MF is generated between the stator core 31 (stator 30) and the ring magnet 43 (rotor 40) to move the rotor 40 to the other axial direction. That is, the magnetic attraction force MF acts in the axial direction of the rotating shaft 41 to make the deviation amount AD "0 (zero)," that is, to align the magnet center MC with the core center CC.

[0089] Specifically, when a drive current is supplied to each of the three-phase coils 34, a magnetic flux (not shown) is generated between the stator core 31 and the ring magnet 43. At this time, a magnetic attraction force MF is generated from one axial side of the rotating shaft 41 to the other axial side, in an attempt to balance the magnetic flux on the left and right sides in the drawing, centered on the core center CC and the magnet center MC.

[0090] As a result, magnetic attraction force MF acts in the direction indicated by the large white arrow, pressing rotor 40 toward first ball bearing 23. Therefore, inner ring 23b of first ball bearing 23 is pressed axially toward the other side relative to outer ring 23a, eliminating any rattle of first ball bearing 23, i.e., any axial rattle of inner ring 23b relative to outer ring 23a.

[0091] In contrast, on one axial side of the rotor 40, an anti-rattle spring SP is arranged with an initial load applied between the opposing member 45 and the inner ring 26b of the second ball bearing 26. Therefore, the spring force SF of the anti-rattle spring SP acts as shown by the small white arrow, pressing the inner ring 26b of the second ball bearing 26 from the other axial side of the rotating shaft 41 toward one axial side.

[0092] This eliminates rattle of the second ball bearing 26, i.e., rattle of the inner ring 26b in the axial direction relative to the outer ring 26a. Note that the spring force SF of the rattle suppression spring SP does not need to be very large, as it is sufficient to eliminate rattle only in the second ball bearing 26 while the electric motor unit 20 is running. Therefore, a small and lightweight spring can be used for the rattle suppression spring SP.

[0093] As described above in detail, according to this embodiment, as shown in Figure 9, the axial center (magnet center MC) of the ring magnet 43 is shifted with respect to the axial center (core center CC) of the stator core 31 on the opposite side of the abutting direction of the abutting member 44 against the first ball bearing 23 (one axial side of the rotating shaft 41).

[0094] As a result, by supplying a drive current to each coil 34 to drive the electric motor unit 20, a magnetic attractive force MF that tries to move (press) the rotor 40 in the other axial direction can be generated. Therefore, the action of the magnetic attractive force MF can be prevented from causing the rotor 40 to lose its axial position and shift. As a result, the distance between the ring magnet 43 and the three Hall elements Hu, Hv, and Hw in the axial direction of the rotating shaft 41 can be maintained constant, enabling stable sensing while suppressing an increase in inertial mass.

[0095] Furthermore, according to this embodiment, one axial side of the rotating shaft 41 is rotatably supported by the second ball bearing 26 fixed to the cover member 25, and an opposing member 45 that faces the second ball bearing 26 in the axial direction of the rotating shaft 41 is provided between the second ball bearing 26 and the ring magnet 43 in the axial direction of the rotating shaft 41, and a rattle suppression spring SP to which a compressive load is applied is arranged between the second ball bearing 26 and the opposing member 45 in the axial direction of the rotating shaft 41.

[0096] This also eliminates axial rattle of the rotary shaft 41 in the second ball bearing 26, which rotatably supports one axial side of the rotary shaft 41. This reduces mechanical noise generated when the seat motor 10 is driven, further improving quietness.

[0097] Furthermore, according to this embodiment, the first and second ball bearings 23, 26 have outer rings 23a, 26a arranged radially outward, inner rings 23b, 26b arranged radially inward, and steel balls 23c, 26c arranged between the outer rings 23a, 26a and the inner rings 23b, 26b, and the outer rings 23a, 26a are fixed to a bearing support tube 22a provided in the casing 21 and a bearing support hole 25b provided in the cover member 25, respectively, and the inner rings 23b, 26b are mounted on the rotating shaft 41 so as to be movable in the axial direction of the rotating shaft 41.

[0098] As a result, the rotor 40 and rattle suppression spring SP, which are arranged so as to be stretched between the inner ring 23b of the first ball bearing 23 and the inner ring 26b of the second ball bearing 26, can eliminate axial rattle of the first and second ball bearings 23, 26.

[0099] According to the present embodiment, a total of three Hall elements Hu, Hv, and Hw are provided on cover member 25, facing ring magnet 43 in the axial direction of rotating shaft 41. Furthermore, a first sun gear 71 that drives planetary gear reducer 60 is fixed to rotating shaft 41.

[0100] This enables stable sensing by the three Hall elements Hu, Hv, and Hw, while optimizing the meshing of the first sun gear 71 with the first planetary gear 72, thereby enabling efficient driving of the planetary gear reducer 60. As a result, the power consumption of the seat motor 10 can be reduced.

[0101] Furthermore, according to this embodiment, the power consumption of the seat motor 10 can be reduced, which makes it possible to achieve the Sustainable Development Goals (SDGs) established by the United Nations, particularly Goal 7 (Ensure access to affordable, reliable, sustainable and modern energy for all) and Goal 13 (Take urgent action to combat climate change and its impacts).

[0102] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the magnetic attractive force MF is applied from one axial side of the rotating shaft 41 toward the other axial side of the rotating shaft 41 (from the right to the left in FIG. 9), but the present invention is not limited to this, and the magnetic attractive force MF can also be applied from the other axial side of the rotating shaft 41 toward one axial side of the rotating shaft 41 (from the left to the right in FIG. 9).

[0103] In this case, the abutting member 44 is disposed on one axial side of the rotating shaft 41, the opposing member 45 and the rattle suppression spring SP are disposed on the other axial side of the rotating shaft 41, and the axial center of the ring magnet 43 is shifted toward the other axial side of the rotating shaft 41 with respect to the axial center of the stator core 31. In this way, when the direction in which the magnetic attractive force MF acts is reversed (opposed), the other axial side of the rotating shaft 41 (the left side in FIG. 9) becomes what is referred to as the one axial side of the rotating shaft in the present invention. In other words, the one axial side and the other axial side are reversed.

[0104] Furthermore, in the above embodiment, the seat motor 10 is shown as an example of a motor device, but the present invention is not limited to this and can also be applied to the drive sources of other in-vehicle devices, such as power window devices and sunroof devices.

[0105] Furthermore, the material, shape, size, number, installation location, etc. of each component in the above-described embodiments are arbitrary as long as they can achieve the present invention, and are not limited to the above-described embodiments. [Explanation of symbols]

[0106] 10: seat motor (motor device), 20: electric motor section, 21: casing (motor case), 21a: engaging claw, 21b: arc-shaped corner section, 22: bottom wall section, 22a: bearing support tube (bearing fixing section), 22b: screw hole, 23: first ball bearing (bearing, rolling bearing), 23a: outer ring, 23b: inner ring, 23c: steel ball (rolling element), 24: opening, 25: cover member (motor case), 25a: engaging recess, 25b: bearing support hole (bearing fixing section), 26: second ball bearing (another bearing, rolling bearing), 26a: outer ring, 26b: inner ring, 26 c: steel ball (rolling element), 27: conductive material holding plate, 29: sensor board, 29a: through hole, 30: stator, 31: stator core, 31a: press-fit corner portion, 32: teeth, 33: insulator, 34: coil, 40: rotor, 41: rotating shaft, 41a: small diameter portion, 42: rotor core, 42a: fixing hole, 43: ring magnet (magnet), 44: abutment member, 44a: cylindrical fixing portion, 44b: abutment portion, 44c: annular flat portion, 45: opposing member, 45a: cylindrical fixing portion, 45b: spring support portion, 45c: annular flat portion, 50: reduction mechanism portion, 51: Reducer case, 51a: engaging claw, 52: annular bottom wall, 52a: fitting tube, 53: opening, 60: planetary gear reducer (driven object), 61: gearbox, 61a: internal gear, 61b: large diameter portion, 61c: small diameter portion, 61d: box opening, 62: third ball bearing, 62a: outer ring, 62b: inner ring, 62c: steel ball, 63: closing member, 63a: through hole, 70: first planetary gear reducer, 71: first sun gear (drive gear), 72: first planetary gear, 73: first carrier, 80: second planetary gear reducer, 81: second sun gear, 81a: hollow part, 82: second planetary gear, 83: second carrier, 83a: pin hole, 84: output shaft, AD: deviation amount, CC: core center, CN: connector, CR: on-board controller, Cu, Cv, Cw: conductive material, Hu, Hv, Hw: hall element (magnetic sensor), MC: magnet center, MF: magnetic attraction force, PL: power line, PN: support pin, S: fixing screw, SC: screw, SF: spring force, SH: engagement shoulder, SP: rattle suppression spring (coil spring), ST: seat member, SW: sensor wire, Tu, Tv, Tw: connection terminal, WT: crossover wire

Claims

1. A motor device including a stator and a rotor, The stator includes: a stator core fixed to the radially inner side of the motor case; a coil wound around a tooth provided on the stator core; and The rotor is a rotating shaft rotatably supported by a bearing fixed to the motor case; a magnet provided integrally with the rotating shaft; an abutting member fixed to the rotary shaft and abutted against the bearing from one axial side of the rotary shaft toward the other axial side of the rotary shaft; Equipped with an axial center portion of the magnet is shifted with respect to an axial center portion of the stator core in a direction opposite to a direction in which the abutting member abuts against the bearing; Motor device.

2. 2. The motor device according to claim 1, one axial side of the rotary shaft is rotatably supported by another bearing fixed to the motor case, an opposing member that faces the other bearing in the axial direction of the rotating shaft is provided between the other bearing and the magnet in the axial direction of the rotating shaft, a coil spring to which a compressive load is applied is disposed between the other bearing and the opposing member in the axial direction of the rotating shaft; Motor device.

3. 3. The motor device according to claim 2, The bearing and the other bearing are an outer ring disposed radially outward; an inner ring disposed radially inward; a rolling element disposed between the outer ring and the inner ring; A rolling bearing having the outer ring is fixed to a bearing fixing portion provided in the motor case, The inner ring is attached to the rotating shaft so as to be movable in the axial direction of the rotating shaft. Motor device.

4. The motor device according to any one of claims 1 to 3, a magnetic sensor provided in the motor case and facing the magnet in the axial direction of the rotation shaft; Motor device.

5. The motor device according to any one of claims 1 to 3, A drive gear for driving a driven object is fixed to the rotation shaft. Motor device.

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