Motor unit

Abstract

To provide a motor unit that suppresses the length of a shaft and the length of a housing in the axial direction of the shaft more than before while suppressing discharge from the shaft and damage to members in contact with the shaft.SOLUTION: A motor unit 1 includes a motor including a rotor 21 and a shaft 22, a housing including the motor, a bearing 41 that rotatably supports the shaft, a resolver 28, and a contact member 6 having electrical conductivity and in contact with the shaft, and the contact member, the resolver, and the bearing are arranged side by side along the axial direction on the other axial side of the shaft on the one axial side. The contact member is arranged on the other axial side of the resolver in the axial direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a motor unit.

Background Art

[0002] Devices for discharging electric charges accumulated on a shaft are known. For example, a shaft grounding device for a vehicle having a grounding member that contacts a rotating shaft and grounds the rotating shaft through the grounding member, the grounding member having a sliding contact portion that slidably contacts and conducts with an end surface of the rotating shaft is known (see, for example, Japanese Patent Application Laid-Open No. 2019-192491).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric device using a motor, electric charges may accumulate on the shaft. And, due to the accumulated electric charges, discharge may occur. When discharge occurs, the electric charges are discharged all at once. Due to the discharge current, the members in contact with the shaft may be damaged. When the discharge is repeated, the damage to the members in contact with the shaft gradually increases. As a result, the accumulated damage may inhibit the operation of the device. Therefore, a static elimination member that contacts the shaft and discharges the electric charges may be attached to the shaft.

[0005] Conventionally, the static elimination member has been provided at the end of the shaft. When the static elimination member is provided at the end of the shaft, a space for arranging the static elimination member is required. Therefore, when the static elimination member is provided at the end of the shaft, the size of the unit (housing) that houses the shaft increases. Also, in order to avoid interference between the static elimination member and other members, the shaft may become longer.

[0006] Therefore, the present invention suppresses the length of the shaft and the length of the housing in the axial direction of the shaft, while suppressing discharge from the shaft and damage to the member in contact with the shaft, as compared with the prior art.

Means for Solving the Problems

[0007] An exemplary motor unit of the present invention includes a motor, a housing, a bearing, a resolver, and a contact member. The motor includes a rotor and a shaft. The housing houses the motor. The bearing is fixed to the housing and rotatably supports the shaft. The resolver has a resolver rotor fixed to the shaft and a resolver stator fixed to the housing. The contact member has conductivity and contacts the shaft. The shaft is attached to the rotor and rotates about the rotation axis. The contact member, the resolver, and the bearing are arranged side by side along the axial direction of the shaft on the other side rather than on one side of the end portion of the shaft in the axial direction. The contact member is arranged on the other side in the axial direction rather than the resolver in the axial direction.

Advantages of the Invention

[0008] According to the exemplary motor unit of the present invention, the length of the shaft and the length of the housing in the axial direction of the shaft are suppressed as compared with the prior art. Moreover, discharge from the shaft can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0010] Hereinafter, the motor unit 1 according to the embodiment of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments and can be arbitrarily changed within the scope of the technical idea of the present invention.

[0011] In this specification, the direction parallel to the rotation axis J2 of the rotor 21 and the shaft 22 of the motor 2 is referred to as the "axial direction" of the motor unit 1. One axial side N and the other axial side T are defined as shown in FIG. 1. Specifically, in the axial direction, among the motor 2 and the speed reduction device 3, the side on which the motor 2 is arranged is the one axial side N. Also, among the motor 2 and the speed reduction device 3, the side on which the speed reduction device 3 is arranged is the other axial side T. Further, the radial direction orthogonal to the rotation axis J2 is simply referred to as the "radial direction". Also, the circumferential direction centered on the rotation axis J2 is simply referred to as the "circumferential direction". Furthermore, in this specification, the "parallel direction" includes not only the case of being completely parallel but also the case of being substantially parallel. And "extending along" a predetermined direction or plane includes not only the case of extending strictly in the predetermined direction but also the case of extending in a direction inclined within a range of less than 45° with respect to the strict direction.

[0012] Hereinafter, an example of the motor unit 1 according to the embodiment will be described with reference to FIGS. 1 to 4.

[0013] <Motor unit 1> Hereinafter, the motor unit 1 according to an exemplary embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing an example of the motor unit 1 according to the embodiment. FIG. 2 is an example of a cross-sectional view taken along a plane including the rotation axis J2 of the motor unit 1 according to the embodiment. Note that FIG. 1 is merely a conceptual diagram. The arrangement and dimensions of each part in FIG. 1 are not necessarily the same as those of the actual motor unit 1.

[0014] The motor unit 1 may be mounted on a vehicle as a power source. The vehicle is, for example, a hybrid vehicle (HV), a plug-in hybrid vehicle (PHV), or an electric vehicle (EV). Note that the motor unit 1 may be used as a power source for vehicles other than automobiles.

[0015] As shown in FIG. 1, the motor unit 1 includes a motor 2, a reduction gear 3, a housing 5, and a contact member 6. The housing 5 houses the motor 2, the reduction gear 3, and the contact member 6. The motor 2 is disposed on one axial side N of the shaft 22. The reduction gear 3 is connected to the other axial side T of the shaft 22. The housing 5 includes a first housing 51 that houses the motor 2 and a second housing 54. The second housing 54 is fixed to the first housing 51 and is located on the other axial side of the first housing 51. For example, the second housing 54 houses the reduction gear 3.

[0016] <Motor 2> The motor 2 is, for example, a brushless motor. Electric power for driving the motor 2 is supplied from an inverter (not shown). The motor 2 has a rotor 21 and a stator 25. The rotor 21 includes a shaft 22 and rotates about the rotation axis J2. That is, the motor 2 includes the rotor 21 and the shaft 22. The shaft 22 is attached to the rotor 21 and rotates about the rotation axis J2. When the motor unit 1 is attached to a vehicle and the vehicle is on a horizontal plane, the rotation axis J2 extends in the horizontal direction. The stator 25 is located radially outward of the rotor 21. The motor 2 is an inner rotor type motor in which the rotor 21 is rotatably disposed inside the stator 25.

[0017] <Rotor 21> When power is supplied from the inverter to the stator 25, the rotor 21 rotates. As shown in FIG. 2, the rotor 21 includes a shaft 22, a rotor core 23, and rotor magnets 24. The shaft 22 extends in the vehicle width direction about the rotation axis J2. The shaft 22 rotates about the rotation axis J2. Inside the shaft 22, a lubricating fluid CL (coolant), which will be described later, flows. For example, the lubricating fluid CL is oil. Therefore, the shaft 22 has a hollow portion 221. The hollow portion 221 is provided inside the shaft 22 and extends along the rotation axis J2. In other words, a cavity extending axially is provided inside the shaft 22. An inlet 220 is provided on the other axial side T of the shaft 22. The lubricating fluid CL flows into the hollow portion 221 from the inlet 220. This lubricating fluid CL is supplied to the motor 2 through a first shaft through-hole 222 that penetrates the shaft 22 in the radial direction. The shaft 22 can also be lightened.

[0018] The first bearing 41, the second bearing 42, the third bearing 43, and the fourth bearing 44 are fixed to the housing 5. Specifically, the first bearing 41 is fixed to the first housing 51 and rotatably supports one axial side N of the shaft 22. Also, the second bearing 42 is fixed to the second housing 54 and rotatably supports the other axial side T of the shaft 22. The third bearing 43 and the fourth bearing 44 also rotatably support the shaft 22.

[0019] Note that the shaft 22 may be divisible. For example, in the housing 5, it may be divisible into a portion within the motor accommodation space 501 and a portion within the gear portion accommodation space 502. For connecting the divided shafts 22, for example, a screw coupling using male and female threads can be adopted. Also, the shafts 22 may be connected by a spline fitting structure. In the case of the spline fitting structure, female splines are provided on the inner peripheral surface of one shaft 22, and male splines are provided on the other shaft 22. Further, the shafts 22 may be connected by press fitting or welding. When adopting fixing methods such as press fitting and welding, serration combining concave and convex portions extending in the axial direction may be adopted. Note that the shaft 22 may be formed as a single member.

[0020] The rotor core 23 is formed by laminating thin plate-shaped electromagnetic steel sheets. The rotor core 23 is a cylinder extending along the axial direction. A plurality of rotor magnets 24 are fixed to the rotor core 23. The plurality of rotor magnets 24 are arranged along the circumferential direction with alternating magnetic poles.

[0021] <Stator 25> As shown in FIG. 2, the stator 25 includes a stator core 26, a coil 27, and an insulator (not shown). The insulator is interposed between the stator core 26 and the coil 27. The stator 25 is held by the housing 5. The stator core 26 has a plurality of magnetic pole teeth (not shown) extending radially inward from the inner peripheral surface of the annular yoke. The coil 27 is formed by winding an electric wire around the magnetic pole teeth. The coil 27 is connected to an inverter unit (not shown) via a bus bar (not shown). Note that a bus bar (not shown) is arranged at an end on one axial side N inside the housing 5. The bus bar connects the inverter unit and the coil 27 and supplies power to the coil 27. Power is supplied to the coil 27 from one axial side N.

[0022] <Resolver 28> On one axial end N of the shaft 22, a resolver 28 (see FIGS. 2 and 3) is attached. The resolver 28 detects the position of the rotor 21, that is, the rotation angle. The resolver 28 has a resolver rotor 281 fixed to the shaft 22 and a resolver stator 282 fixed to the housing 5.

[0023] The resolver rotor 281 and the resolver stator 282 are annular. The inner peripheral surface of the resolver stator 282 and the outer peripheral surface of the resolver rotor 281 face each other in the radial direction. The resolver stator 282 periodically detects the position of the resolver rotor 281 when the rotor 21 rotates. Thereby, the resolver 28 acquires information on the position of the rotor 21.

[0024] <Reduction gear 3> The reduction gear 3 is housed in the housing 5 (gear portion housing space 502). The reduction gear 3 includes a plurality of gears and a plurality of shafts. As described above, the reduction gear 3 is connected to the shaft 22 on the other axial side T. The reduction gear 3 has an intermediate shaft 31 and an output shaft 32.

[0025] <Shaft 22> First, the first gear 71 is disposed on the outer peripheral surface of the shaft 22. The first gear 71 and the shaft 22 may be formed of a single member. The first gear 71 rotates about the rotation axis J2 together with the shaft 22.

[0026] <Intermediate shaft 31> The intermediate shaft 31 extends along the intermediate axis J4. The intermediate axis J4 is parallel to the rotation axis J2. Both axial ends of the intermediate shaft 31 are rotatably supported by bearings. These bearings are provided in the housing 5. That is, the intermediate shaft 31 is rotatable about the intermediate axis J4. The intermediate shaft 31 has a second gear 72 which is an intermediate gear and a third gear 73 which is a final drive gear.

[0027] The second gear 72 and the third gear 73 are arranged on the intermediate shaft 31. The second gear 72 meshes with the first gear 71. The third gear 73 meshes with the ring gear 74 of the output shaft 32. The torque of the shaft 22 is transmitted from the first gear 71 to the second gear 72. Then, the torque transmitted to the second gear 72 is transmitted to the third gear 73 via the intermediate shaft 31. The torque transmitted to the third gear 73 is transmitted to the ring gear 74 of the output shaft 32. In this way, the intermediate shaft 31 transmits the output torque of the motor 2 to the output shaft 32. The gear ratio and the number of gears of each gear can be variously changed according to the required reduction ratio.

[0028] <output shaft 32> The output shaft 32 extends along the output axis J5. The output axis J5 is parallel to the rotation axis J2 and the intermediate axis J4. The output shaft 32 is rotatable about the output axis J5. The output shaft 32 protrudes outside the housing 5. A drive shaft (not shown) connected to the drive wheels of the vehicle is connected to the output shaft 32. The torque of the output shaft 32 is transmitted to the drive wheels. The output shaft 32 may be provided with a mechanism that absorbs the speed difference between the left and right drive wheels during vehicle turning and transmits the same torque to the left and right of the output shaft 32.

[0029] In this way, the intermediate shaft 31 is connected to the shaft 22. The intermediate shaft 31 transmits the output torque of the motor 2 to the output shaft 32. The intermediate shaft 31 reduces the rotational speed of the motor 2 according to the reduction ratio. Also, the intermediate shaft 31 increases the output torque of the motor 2 according to the reduction ratio. Note that the reduction gear 3 may have a parking mechanism (not shown) that locks the vehicle when the motor unit 1 stops operating.

[0030] <housing 5> As shown in FIG. 1, FIG. 2, etc., the housing 5 has a first housing 51, a bearing holder 52, a cover member 53, and a second housing 54. The first housing 51, the bearing holder 52, the cover member 53, and the second housing 54 are formed of a conductive metal. For example, the material may be iron, aluminum, or an alloy thereof. However, the material is not limited thereto. Note that the materials of the first housing 51, the bearing holder 52, the cover member 53, and the second housing 54 may be the same or different. In order to suppress dissimilar metal contact corrosion, it is preferable to form them of the same material.

[0031] <First housing 51> The first housing 51 has a first cylindrical portion 511, a partition wall portion 512, a protruding portion 513, and a bearing holder 52. The first cylindrical portion 511 is a cylindrical body extending in the axial direction. The first cylindrical portion 511 has an opening on one axial side N. The partition wall portion 512 extends radially inward from the end on the other axial side T of the first cylindrical portion 511. A through hole 514 penetrating along the rotation axis J2 is provided in the partition wall portion 512. The through hole 514 has a circular cross section, and its center line coincides with the rotation axis J2. And the shaft 22 penetrates through the through hole 514. The shaft 22 is rotatably supported by the partition wall portion 512 via a third bearing 43 and a fourth bearing 44. The third bearing 43 is disposed on one axial side N of the through hole 514 in the partition wall portion 512. The fourth bearing 44 is disposed on the other axial side T of the through hole 514 in the partition wall portion 512. Thereby, the shaft 22 is rotatably supported at an intermediate portion in the axial direction. As a result, the vibration, deflection, etc. of the rotating shaft 22 are suppressed.

[0032] The protruding portion 513 is flat. The protruding portion 513 extends vertically downward from the outer peripheral surface of the first cylindrical portion 511 on the other axial side T. In the motor unit 1, the first cylindrical portion 511, the partition wall portion 512, and the protruding portion 513 are formed of a single member. The partition wall portion 512 and the protruding portion 513 close the end on one axial side N of the second housing 54.

[0033] The protruding portion 513 is provided with a first drive shaft through hole 515. The first drive shaft through hole 515 is a hole that penetrates the protruding portion 513 in the axial direction. The output shaft 32 penetrates through the first drive shaft through hole 515 in a rotatable state. In order to suppress the leakage of the lubricating fluid CL, an oil seal (not shown) is provided between the output shaft 32 and the first drive shaft through hole 515. A vehicle axle (not shown) for rotating the wheel is connected to the tip of the output shaft 32.

[0034] <Bearing holder 52> The bearing holder 52 expands in the radial direction. The bearing holder 52 is fixed to one axial side N of the first cylindrical portion 511 using screws. That is, the bearing holder 52 is fixed to the first cylindrical portion 511 as a part of the first housing 51. And the bearing holder 52 closes the opening on one axial side N of the first cylindrical portion 511. However, the fixing method is not limited to this. The bearing holder 52 may be firmly fixed using other methods such as screwing or press-fitting.

[0035] As a result, the bearing holder 52 is electrically connected to the first housing 51. Electrically connected includes cases where they are physically in contact and conductive, as well as cases where they are close enough to be at approximately the same potential. That is, the members that are electrically connected have the same potential or approximately the same potential. Hereinafter, when referring to being electrically connected, it means the same configuration. In the motor unit 1, the first housing 51 and the bearing holder 52 have the same potential. Note that the housing 5 is grounded. In other words, the housing 5 is electrically connected to the ground. The charge of the housing 5 flows towards the ground.

[0036] Also, the first cylindrical portion 511 and the bearing holder 52 are in close contact. Here, being in close contact means having a sealing property such that the lubricating fluid CL inside the housing 5 does not leak to the outside, and foreign substances such as external water, dust, and dirt do not enter. Hereinafter, when referring to being in close contact, it means the same configuration.

[0037] The bearing holder 52 has a recess 521. The recess 521 is recessed from the surface on one axial side N of the bearing holder 52 toward the other axial side T. A through hole 520 that penetrates axially is formed in the bottom surface of the recess 521. The center of the through hole 520 coincides with the rotation axis J2, and the shaft 22 penetrates through the through hole 520. The end portion on one axial side N of the shaft 22 is disposed inside the recess 521.

[0038] A first bearing 41 is disposed on the other axial side T of the bearing holder 52. The shaft 22 passing through the through hole 520 is rotatably supported by the bearing holder 52 via the first bearing 41.

[0039] Inside the recess 521, the resolver stator 282 of the resolver 28 is fixed. That is, the resolver stator 282 is fixed to the bearing holder 52. The center line of the resolver stator 282 disposed on the bearing holder 52 coincides with the rotation axis J2. The resolver stator 282 may be fixed to the bearing holder 52 by screws (not shown). Also, the resolver stator 282 may be fixed to the bearing holder 52 by press-fitting or adhesion. Other fixing methods may be adopted.

[0040] The portion on the other axial side T of the shaft 22 from the rotor core 23 penetrates through the through hole 514. The portion on one axial side N of the shaft 22 from the rotor core 23 penetrates through the through hole 520. And both sides of the rotor core 23 of the shaft 22 in the axial direction are rotatably supported by the housing 5 via the first bearing 41 and the third bearing 43. At this time, the shaft 22 is rotatable around the rotation axis J2.

[0041] <Cover member 53> The cover member 53 is attached to one axial side N of the bearing holder 52. The cover member 53 covers the recess 521 of the bearing holder 52 from one axial side N. Further, the cover member 53 is in close contact with the bearing holder 52. Also, the bearing holder 52 and the cover member 53 are electrically connected. Therefore, the cover member 53 and the first housing 51 are at the same potential. For this reason, the charge of the cover member 53 is removed.

[0042] <Second housing 54> The second housing 54 has a concave shape that opens to one axial side N. The second housing 54 has a second cylindrical portion 541 and a closing portion 542. The end of the second cylindrical portion 541 on one axial side N is attached to the partition wall portion 512. The second cylindrical portion 541 axially overlaps with the outer edge portion of the partition wall portion 512. The second cylindrical portion 541 is in close contact with the partition wall portion 512 and is in electrical contact. The second cylindrical portion 541 may be fixed to the partition wall portion 512 by screwing, or may be fixed by welding or press-fitting. Other fixing methods may be adopted. The opening of the second cylindrical portion 541 is covered by the partition wall portion 512.

[0043] The second cylindrical portion 541 and the closing portion 542 are formed of a single member. The closing portion 542 is plate-shaped and extends radially inward from the end of the second cylindrical portion 541 on the other axial side T. The space surrounded by the second cylindrical portion 541, the closing portion 542, and the partition wall portion 512 is the gear portion accommodation space 502. The end of the shaft 22 on the other axial side T is rotatably supported by the closing portion 542 via the second bearing 42.

[0044] A second drive shaft through hole 543 is formed in the closing portion 542. The second drive shaft through hole 543 is a hole that axially penetrates the closing portion 542. The output shaft 32 penetrates through the second drive shaft through hole 543 in a rotatable state. In order to suppress the leakage of the lubricating fluid CL, an oil seal (not shown) is provided between the output shaft 32 and the second drive shaft through hole 543. The output shaft 32 rotates around the output shaft J5.

[0045] <Circulation of the lubricating fluid CL> The interior of the housing 5 is filled with a lubricating fluid CL. The lubricating fluid CL lubricates each gear and each bearing of the speed reduction device 3. The lubricating fluid CL is also used for cooling the motor 2. That is, the lubricating fluid CL for lubrication of the motor unit 1 is also the cooling fluid of the motor 2.

[0046] As shown in FIG. 1, the lubricating fluid CL accumulates in the lower region of the gear portion accommodating space 502. A part (ring gear 74) of the output shaft 32 is immersed in the lubricating fluid CL stored in the gear portion accommodating space 502. By the operation of the output shaft 32, the stored lubricating fluid CL is scraped up and diffused inside the gear portion accommodating space 502. The scraped-up lubricating fluid CL is supplied to each gear inside the gear portion accommodating space 502. The scraped-up lubricating fluid CL is also supplied to each bearing. The lubricating fluid CL is used for lubricating each gear and each bearing.

[0047] As shown in FIG. 1, a catch tank 57 is arranged in the upper region of the gear portion accommodating space 502. The catch tank 57 opens upward. A part of the scraped-up lubricating fluid CL flows into the catch tank 57. The lubricating fluid CL accumulated in the catch tank 57 flows into the hollow portion 221 of the shaft 22 through an oil supply passage (not shown) and an inlet 220. The lubricating fluid CL in the hollow portion 221 flows toward one axial side N. The lubricating fluid CL that has flowed through the hollow portion 221 is sprayed onto the stator 25. The lubricating fluid CL also cools the stator 25.

[0048] Due to the escape of the airflow toward one axial side N during the rotation of the shaft 22, a negative pressure is generated. By this negative pressure, the lubricating fluid CL can be drawn into the interior of the shaft 22 from the inlet 220. Thereby, the lubricating fluid CL can be supplied to the entire motor 2. Also, the motor 2 can be stably cooled.

[0049] <Liquid circulation section 8> The motor unit 1 has a liquid circulation section 8 that circulates the lubricating liquid CL. The liquid circulation section 8 has a piping section 81, a pump 82, an oil cooler 83, and a motor oil reservoir 84. The piping section 81 is a pipe formed in the housing 5. The piping section 81 connects the pump 82 and the motor oil reservoir 84 disposed inside the first cylindrical section 511. The piping section 81 supplies the lubricating liquid CL to the motor oil reservoir 84. The pump 82 sucks in the lubricating liquid CL stored in the lower region of the gear section accommodation space 502. The pump 82 may be an electric pump. The pump 82 may be driven using a part of the output of the output shaft 32 of the motor unit 1. A pump 82 other than those described above may be used.

[0050] The oil cooler 83 is disposed between the pump 82 and the motor oil reservoir 84. That is, the lubricating liquid CL sucked by the pump 82 passes through the oil cooler 83 via the piping section 81 and is sent to the motor oil reservoir 84. For example, a refrigerant supplied from the outside is supplied to the oil cooler 83. For example, the refrigerant is water. Then, the temperature of the lubricating liquid CL decreases due to the heat exchange between the refrigerant and the lubricating liquid CL. Note that the oil cooler 83 is not limited to a liquid-cooled type. The oil cooler 83 may be an air-cooled type cooled by the running wind of the vehicle. By using the oil cooler 83, the cooling efficiency of the motor 2 can be increased.

[0051] The motor oil reservoir 84 is disposed in the upper region of the motor accommodation space 501. The motor oil reservoir 84 is a tray that opens upward. A dripping hole is formed at the bottom of the motor oil reservoir 84. The lubricating liquid CL dripping from the dripping hole cools the motor 2. The dripping hole is formed, for example, above the coil end of the coil 27 of the stator 25, and the coil 27 is cooled by the lubricating liquid CL.

[0052] <Contact member 6> When the motor 2 operates, the shaft 22 becomes charged. In other words, electric charges accumulate on the shaft 22. When the electric charges are accumulated, discharge may occur from the shaft 22 due to the potential rise of the shaft 22. The discharge here means that an electric current flows from the shaft 22 to a member in contact with the shaft 22.

[0053] For example, a lubricating fluid CL adheres to each bearing that supports the shaft 22. However, when the outer ring of the bearing and the ball make metal contact due to a shortage of the lubricating fluid CL, the electric charges on the shaft 22 may be discharged all at once. To remove the electric charges on the shaft 22, the motor unit 1 includes a contact member 6. The contact member 6 is a member that discharges the shaft 22. Thereby, discharge can be suppressed. That is, the motor unit 1 has a contact member 6 that has conductivity and is in contact with the shaft 22 and is electrically connected to the housing 5.

[0054] The contact member 6 will be described with reference to FIGS. 2 to 4. FIG. 3 is a diagram showing an example of the contact member 6 according to the embodiment. FIG. 4 is an enlarged cross-sectional view of a portion of the motor unit 1 where the contact member 6 is provided. FIG. 4 is an enlarged view of a part of FIG. 2.

[0055] As shown in FIG. 4, the contact member 6 contacts the bearing holder 52. Also, as shown in FIG. 3, the contact member 6 includes a ring portion 61 and a brush portion 62. The ring portion 61 is annular. The brush portion 62 is fixed to the inner peripheral surface of the ring portion 61 and contacts the shaft 22. The ring portion 61 is circular annular. The material of the ring portion 61 is a material having conductivity such as metal. Also, the brush portion 62 has conductivity. The material of the brush portion 62 is a material that can bend in the circumferential direction. A wire made of carbon fiber may be used for the brush portion 62. Also, other conductive materials may be used for the brush portion 62. Also, the brush portion 62 is not limited to a wire. For example, the brush portion 62 may be a film. The brush portion 62 is fixed to the inner peripheral surface of the ring portion 61. The ring portion 61 and the brush portion 62 are electrically connected. Since the contact member 6 contacts the bearing holder 52, the contact member 6 and the shaft 22 are electrically connected to the housing 5.

[0056] The shaft 22 penetrates through the through hole of the ring portion 61. The brush portion 62 protrudes radially inward. The brush portion 62 contacts the outer peripheral surface of the shaft 22. Hereinafter, the portion of the shaft 22 that contacts the brush portion 62 is referred to as the contacted portion. The length from the inner peripheral surface of the ring portion 61 to the axially inner end of the brush portion 62 is longer than the radial distance from the ring portion 61 to the contacted portion. Therefore, the radially inner end of the brush portion 62 contacts the contacted portion while bending. In this way, the shaft 22 penetrates the contact member 6. And the brush portion 62 contacts the surface of the shaft 22 in the circumferential direction. By the contact between the brush portion 62 and the shaft 22, the electric charge stored in the shaft 22 can be removed. Note that the contacted portion is formed on the outer peripheral surface of the shaft 22. Therefore, even if the shaft 22 moves in the axial direction, the brush portion 62 continues to contact the contacted portion. That is, even if the shaft 22 moves in the axial direction, the electrical connection (continuity) between the shaft 22 and the housing 5 is maintained.

[0057] The conductivity of the contacted portion may be higher than the conductivity of the portion (bearing contact portion) that contacts the inner ring of the first bearing 41 of the shaft 22. For example, a conductive film such as silver or copper may be provided as the contacted portion. For example, a conductive metal paste is applied to the portion where the brush portion 62 of the shaft 22 contacts. Note that the conductive film may be formed by plating or vapor deposition. The conductive film may be formed by other methods. If the conductivity of the contacted portion is made higher than the conductivity of the bearing contact portion, most of the electric charges accumulated in the shaft 22 can flow to the contact member 6. The electric corrosion of the bearing can be effectively suppressed.

[0058] <Arrangement of the Contact Member 6, the Resolver 28, and the Bearing> Next, with reference to FIG. 4, an example of the arrangement of the contact member 6, the resolver 28, and the first bearing 41 according to the embodiment will be described. As shown in FIG. 4, the contact member 6, the resolver 28, and the first bearing 41 are arranged side by side along the axial direction in the first housing 51. Conventionally, the contact member 6 has been arranged at the end on one axial side N of the shaft 22. In this case, it is necessary to provide a space for attaching the contact member 6. However, since the contact member 6 is stored in the first housing 51 and arranged on the other axial side T than the resolver 28, it is not necessary to provide an installation space for the contact member 6. Therefore, the shaft 22 can be made shorter compared to the case where the contact member 6 is attached to the end on one axial side N of the shaft 22. Also, the axial length of the motor unit 1 can be made shorter than before.

[0059] Specifically, the contact member 6, the resolver 28, and the bearing (first bearing 41) are arranged side by side along the axial direction on the other axial side T of the shaft 22 with respect to the end on one axial side N. The contact member 6 is arranged on the other axial side T with respect to the resolver 28. That is, the contact member 6 may be arranged on the other axial side T (rotor 21 side) with respect to the resolver 28. The contact member 6 is arranged inside the motor unit 1. Conventionally, the contact member 6 has been arranged at the end on one axial side N of the shaft 22. In this case, it is necessary to provide a space for attaching the contact member 6. However, since the contact member 6 is arranged on the other axial side T with respect to the resolver 28 in the axial direction, there is no need to provide an installation space. Therefore, the shaft 22 can be made shorter compared to the case where the contact member 6 is attached to the end on one axial side N of the shaft 22. Also, the axial length of the motor unit 1 can be made shorter than before. Moreover, the contact member 6 is arranged at a position closer to the bearing than before. Thereby, the electric charge that accumulates in the shaft 22 and attempts to pass through the first bearing 41 can be efficiently collected by the contact member 6. Therefore, the discharge at the first bearing 41 due to the electric charge accumulated in the shaft 22 can be reduced. Thus, the electrolytic corrosion of the first bearing 41 can be suppressed. Note that it is not only the first bearing 41 that can have its electrolytic corrosion suppressed. The electrolytic corrosion can also be suppressed in the second bearing 42, the third bearing 43, and the fourth bearing 44 that are in contact with the shaft 22.

[0060] As shown in FIG. 4, the contact member 6 may be arranged between the resolver 28 and the bearing (first bearing 41) in the axial direction. That is, the contact member 6 can be arranged in the space that was conventionally vacant. The axial lengths of the shaft 22 and the motor unit 1 are shortened.

[0061] Here, the brush portion 62 of the contact member 6 contacts the shaft 22. Therefore, wear powder may be generated due to friction during contact. The wear powder is fine powder. The wear powder may flow out from the contact member 6 by the lubricating liquid CL. If the wear powder enters a moving member (element), it may affect the operation. Thus, as shown in FIG. 4, a first seal member 91 may be arranged. The first seal member 91 may be arranged between the contact member 6 and the bearing (first bearing 41) in the axial direction. The first seal member 91 partitions the contact member 6 and the first bearing 41, and prevents, for example, the entry of objects into the first bearing 41. Thereby, the entry of foreign matter (wear powder) coming out from the contact member 6 into the first bearing 41 can be prevented. Also, the entry of the lubricating liquid CL from the first bearing 41 side into the contact member 6 (brush portion 62) can be prevented. Therefore, it is possible to suppress or prevent a decrease in the charge elimination performance between the shaft 22 and the housing 5 (bearing holder 52) via the contact member 6 due to the entry of the lubricating liquid CL into the contact member 6 (particularly the brush portion 62).

[0062] Also, if the wear powder adheres to the resolver 28, it may affect the operation of the resolver 28. Thus, as shown in FIG. 4, a second seal member 92 may be arranged. The second seal member 92 may be arranged between the contact member 6 and the resolver 28 in the axial direction. The second seal member 92 partitions the contact member 6 and the resolver 28, and prevents, for example, the entry of objects into the resolver 28. The entry of foreign matter (wear powder) coming out from the contact member 6 into the resolver 28 can be prevented. Also, the entry of the lubricating liquid CL from the resolver 28 side into the contact member 6 (brush portion 62) can be prevented.

[0063] For example, the first seal member 91 and the second seal member 92 are ring-shaped rubber packings. However, the materials of the first seal member 91 and the second seal member 92 are not limited to rubber. For example, the first seal member 91 and the second seal member 92 may be films. Materials capable of sealing the lubricating fluid CL from the contact member 6 can be used for the first seal member 91 and the second seal member 92. The materials of the first seal member 91 and the second seal member 92 may be selected from inorganic materials or organic materials other than rubber.

[0064] As described above, the housing 5 stores the lubricating fluid CL for cooling the motor 2 inside. Further, the motor unit 1 includes a lubricating fluid CL circulation unit that circulates the lubricating fluid CL. The seal member (the first seal member 91 or the second seal member 92) can reduce the entry of the lubricating fluid CL into the contact member 6.

[0065] <Fixing of the contact member 6> Next, an example of fixing the contact member 6 will be described with reference to FIG. 4. First, the bearing holder 52 is a part of the housing 5. The bearing holder 52 is disposed on one axial side N of the rotor 21 and holds a bearing (the first bearing 41). As shown in FIG. 4, the contact member 6 may be fixed to the bearing holder 52. Before fixing the bearing holder 52 to the housing 5, the contact member 6 can be attached to the bearing holder 52. After that, if the bearing holder 52 is fixed to the housing 5, the first bearing 41 and the contact member 6 are also attached at the same time. Thereby, when attaching to the motor unit 1, there is no need to separately position a plurality of members. Therefore, the assembly of the motor unit 1 is easy. Moreover, since it is fixed to the bearing holder 52, the contact member 6 and the bearing holder 52 are always electrically connected.

[0066] By press-fitting, the contact member 6 may be fixed to the bearing holder 52. In this case, the shaft 22 is inserted through the ring portion 61 of the contact member 6 fixed to the bearing holder 52. However, the fixing method is not limited to this. The contact member 6 may be fixed to the bearing holder 52 using other methods such as screws or adhesion.

[0067] Note that the contact member 6 may be directly fixed to the shaft 22. It is also possible to directly attach the contact member 6 to the shaft 22. For example, the contact member 6 may be fixed to the bearing holder 52 by screwing.

[0068] Furthermore, as shown in FIG. 4, the first seal member 91 and the second seal member 92 may be fixed to the bearing holder 52. Before fixing the bearing holder 52 to the housing 5, each seal member can also be attached to the bearing holder 52. After attachment, if the bearing holder 52 is fixed to the housing 5, the bearing, the contact member 6, and each seal member are also attached simultaneously. For the seal members, there is no need for positioning work when attaching them to the motor unit 1. Therefore, the assembly of the motor unit 1 is easy.

[0069] By press-fitting, the first seal member 91 and the second seal member 92 may be fixed to the bearing holder 52. However, the fixing method is not limited to this. The contact member 6 may be fixed to the bearing holder 52 using other methods such as screws or adhesion.

[0070] Furthermore, the resolver stator 282 is fixed to the bearing holder 52. When the bearing holder 52 is attached to the motor unit 1, the resolver stator 282 is also attached simultaneously. And by fixing the bearing holder 52, a plurality of members can be attached together with the bearing holder 52. Therefore, the assembly of the motor unit 1 becomes easy.

[0071] The motor unit 1 has a cover member 53 attached to one axial side N of the bearing holder 52. The contact member 6, the resolver 28, and the bearing (first bearing 41) are arranged on the other axial side T with respect to the cover member 53. The cover member 53 can close the one axial side N in the axial direction of the bearing holder 52. Since the length of the shaft 22 is suppressed, the shape of the cover member 53 does not have to protrude on the one axial side N in the axial direction. Therefore, the axial length of the motor unit 1 can be suppressed.

[0072] As described above, the shaft 22 and the contact member 6 are electrically connected. For this reason, for each of the first bearing 41 to the fourth bearing 44, the potential difference between the inner ring attached to the shaft 22 and the outer ring attached to the housing 5 is suppressed. Further, the electric corrosion at each bearing due to discharge is suppressed. As a result, the variation in the rotation of the shaft 22 is suppressed. As a result, the motor unit 1 can be stably driven for a long period of time. In other words, the life of the motor unit 1 is prolonged.

[0073] <First Modification> The first modification will be described with reference to FIG. 5. FIG. 5 is a cross-sectional view of the motor unit 1A cut along a plane including the rotation axis J2. Further, FIG. 5 is an enlarged view of the end portion on the one axial side N of the shaft 22 of the motor unit 1A according to the first modification.

[0074] The first modification is different from the motor unit 1 according to the above-described embodiment in terms of the arrangement of the contact member 6, the resolver 28, and the bearing. The motor unit 1 according to the embodiment and the motor unit 1A according to the first modification are the same except for the arrangement. Hereinafter, the differences between the motor unit 1 according to the embodiment and the motor unit 1A according to the first modification will be described. The common points between the motor unit 1 according to the embodiment and the motor unit 1A according to the first modification are incorporated by reference to the description of the motor unit 1 according to the embodiment. The description of the common points will be omitted unless otherwise specified.

[0075] In the first modification, the contact member 6 is disposed on the other axial side T with respect to the resolver 28 and the bearing (first bearing 41). In other words, in the axial direction, the contact member 6 may be disposed inside the motor 2. In the axial direction, the contact member 6 can be disposed inside the motor unit 1 (on the rotor 21 side) with respect to the resolver 28 and the bearing (first bearing 41). The contact member 6 can be disposed in the space that has been conventionally vacant. The axial lengths of the shaft 22 and the motor unit 1 are shortened.

[0076] As shown in FIG. 5, also in the first modification, a first seal member 91 may be disposed between the contact member 6 and the first bearing 41 in the axial direction. It is possible to prevent foreign matter coming out of the contact member 6 from entering the first bearing 41. For example, entry of wear powder of the contact member 6 into the first bearing 41 is prevented.

[0077] Also, in the first modification, the contact member 6 may be fixed to the bearing holder 52. Also, the first seal member 91 may be fixed to the bearing holder 52. The contact member 6 and the first seal member 91 may be fixed to the bearing holder 52 by press-fitting. However, the fixing method is not limited to this. The contact member 6 and the first seal member 91 may be fixed to the bearing holder 52 using other methods such as screws and adhesion.

[0078] Before fixing the bearing holder 52 to the housing 5, the contact member 6 and the first seal member 91 can be attached to the bearing holder 52. Thereafter, if the bearing holder 52 is fixed to the housing 5, the bearing, the contact member 6, and the first seal member 91 are also attached simultaneously. Therefore, the assembly of the motor unit 1 is easy.

[0079] Furthermore, also in the first modification, the resolver stator 282 may be fixed to the bearing holder 52. If the bearing holder 52 is fixed, a plurality of members can be attached together with the bearing holder 52. The assembly of the motor unit 1 becomes easy.

[0080] <Second Modification Example> The second modification example will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view of the motor unit 1B cut along a plane including the rotation axis J2. Further, FIG. 6 is an enlarged view of an end portion on one axial side N of the shaft 22 of the motor unit 1B according to the second modification example.

[0081] The second modification example is different from the motor unit 1A according to the first modification example described above in terms of the arrangement of the third seal member 93, the second shaft through-hole 223, and the hole portion 522. Except for these arrangements, the motor unit 1B according to the second modification example is the same as the motor unit 1A according to the first modification example. Hereinafter, the differences between the motor unit 1B according to the second modification example and the motor unit 1A according to the first modification example will be described. The common points between the motor unit 1B according to the second modification example and the motor unit 1 according to the embodiment and the motor unit 1A according to the first modification example are such that the descriptions of the motor unit 1 according to the embodiment and the motor unit 1A according to the first modification example are incorporated by reference. Unless otherwise specified, the description of the common points will be omitted.

[0082] In the second modification example, the motor unit 1B has a third seal member 93. The third seal member 93 is disposed on the other axial side T with respect to the contact member 6 in the axial direction and is disposed between the contact member 6 and the rotor 21. The third seal member 93 partitions the contact member 6 from the motor accommodation space 501 and prevents objects from entering the contact member 6. For example, the third seal member 93 can prevent the lubricating fluid CL from entering the contact member 6 (brush portion 62) from the motor accommodation space 501. Therefore, it is possible to suppress or prevent a decrease in the charge removal performance between the shaft 22 and the housing 5 (bearing holder 52) via the contact member 6 due to the entry of the lubricating fluid CL into the contact member 6 (particularly the brush portion 62). Further, it is also possible to prevent foreign matter coming out of the contact member 6 from entering the motor accommodation space 501. For example, it is possible to prevent the wear powder of the contact member 6 from entering the motor accommodation space 501.

[0083] For example, the third seal member 93 is a ring-shaped rubber packing. However, the material of the third seal member 93 is not limited to rubber. For example, the third seal member 93 may be a film. A material capable of sealing the lubricating fluid CL from the contact member 6 can be used for the third seal member 93. The material of the third seal member 93 may be selected from inorganic materials or organic materials other than rubber.

[0084] Also, the third seal member 93 may be fixed to the bearing holder 52. The third seal member 93 may be fixed to the bearing holder 52 by press-fitting. However, the fixing method is not limited to this. The third seal member 93 may be fixed to the bearing holder 52 using other methods such as screws or adhesion.

[0085] Before fixing the bearing holder 52 to the housing 5, the third seal member can be attached to the bearing holder 52 together with the contact member 6 and the first seal member 91. After that, if the bearing holder 52 is fixed to the housing 5, the bearing, the contact member 6, and the first seal member 91 are also attached at the same time. Therefore, the assembly of the motor unit 1 is easy.

[0086] Further, in the second modification, the shaft 22 has a first shaft through-hole 222 and a second shaft through-hole 223. The first shaft through-hole 222 is disposed between the first bearing 41 and the second bearing 42 in the axial direction and penetrates the shaft 22 in the radial direction. The second shaft through-hole 223 is disposed on one axial side N with respect to the first shaft through-hole 222 and penetrates the shaft 22 in the radial direction. The radially outer end portion of the second shaft through-hole 223 is disposed on one axial side N with respect to the first bearing 41. For example, the second shaft through-hole 223 is connected between the resolver 28 and the first bearing 41 from the hollow portion 221. The second shaft through-hole 223 may be singular or plural. Due to the arrangement of the second shaft through-hole 223, when the shaft 22 rotates, air can be supplied to the hollow portion 221 on one axial side N of the shaft 22. Therefore, when the shaft 22 rotates, the negative pressure at one axial end of the hollow portion 221 can be reduced, so that the lubricating fluid CL flowing into the hollow portion 221 of the shaft 22 from the inlet 220 can be smoothly flowed to the first shaft through-hole 222, and the outflow of the lubricating fluid CL from one axial side N of the shaft 22 can be effectively suppressed or prevented.

[0087] Further, in the second modification, the bearing holder 52 has a hole portion 522. The hole portion 522 penetrates from one axial side N to the other axial side T of the bearing holder 52. In the present embodiment, the hole portion 522 is disposed vertically below the shaft 22. Further, the end portion on one axial side N of the hole portion 522 is connected to the lower portion of the space 503 surrounded by the bearing holder 52 and the cover member 53, preferably connected to the lowermost portion of the space 503. The end portion on one axial side N of the shaft 22 is accommodated in the space 503 and is connected to the hollow portion 221. Due to the arrangement of the hole portion 522, even if the lubricating fluid CL flows out from the end portion on one axial side N of the shaft 22 to the space 503, this lubricating fluid CL can be discharged to the motor accommodation space 501 through the hole portion 522. Therefore, it is possible to prevent the lubricating fluid CL from accumulating in the space 503.

[0088] Incidentally, although the second shaft through-hole 223 and the hole portion 522 have been described in the second modification example, they may also be adopted in the embodiment shown in FIG. 4 and the first modification example shown in FIG. 5. However, when the second shaft through-hole 223 is adopted in the embodiment, preferably, the radially outer end portion of the second shaft through-hole 223 is connected between the resolver 28 and the second seal member 92.

[0089] As described above, the embodiments, the first and second modification examples of the present invention have been described. However, each configuration and their combinations in the embodiments are examples, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the spirit of the present invention. Further, the present invention is not limited by the embodiments.

Industrial Applicability

[0090] The motor unit of the present invention can be used, for example, as a motor unit for vehicle drive.

Explanation of Signs

[0091] 1 Motor unit 1A Motor unit 1B Motor unit 2 Motor 21 Rotor 22 Shaft 220 Inlet 221 Hollow portion 222 First shaft through-hole 223 Second shaft through-hole 23 Rotor core 24 Rotor magnet 25 Stator 26 Stator core 27 Coil 28 Resolver 281 Resolver rotor 282 Resolver stator 3 Gear portion 31 Intermediate shaft 32 Output shaft 41 First bearing 42 Second bearing 43 Third bearing 44 Fourth bearing 5 Housing 501 Motor accommodation space 502 Gear portion accommodation space 503 Space 51 First housing 511 First cylindrical part 512 Partition part 513 Protrusion 514 Through hole 515 First drive shaft through hole 52 Bearing holder 520 Through hole 521 Recess 522 Hole part 53 Cover member 54 Second housing 541 Second cylindrical part 542 Closing part 543 Second drive shaft through hole 57 Catch tank 6 Contact member 61 Ring part 62 Brush part 71 First gear 72 Second gear 73 Third gear 74 Ring gear 8 Liquid circulation part 81 Pipe part 82 Pump 83 Oil cooler 84 Motor oil reservoir 91 First seal member 92 Second seal member 93 Third seal member CL Lubricating liquid J2 Rotating shaft J4 Intermediate shaft J5 Output shaft N One side in the axial direction T The other side in the axial direction

Claims

1. A motor including a rotor and a shaft; A reduction gear connected to the other axial side of the shaft; A housing including a first housing that houses the motor and a second housing that is fixed to the first housing and is located on the other axial side; A first bearing fixed to the first housing and rotatably supporting one axial side of the shaft; A second bearing fixed to the second housing and rotatably supporting the other axial side of the shaft; A resolver having a resolver rotor fixed to the shaft and a resolver stator fixed to the housing; A contact member having conductivity and being in contact with the shaft and electrically connected to the housing; The contact member includes a ring portion and a brush portion; The resolver, the contact member, and the first bearing are arranged side by side along the axial direction in the first housing, and are arranged in the order of the resolver, the contact member, and the first bearing from one axial side of the shaft toward the other axial side; A motor unit in which an end portion on the radially outer side of the contact member is located on the radially inner side of an end portion on the radially outer side of the resolver and an end portion on the radially outer side of the first bearing.

2. A motor including a rotor and a shaft; A reduction gear connected to the other axial side of the shaft; A housing including a first housing that houses the motor and a second housing that is fixed to the first housing and is located on the other axial side; A first bearing fixed to the first housing and rotatably supporting one axial side of the shaft; A second bearing fixed to the second housing and rotatably supporting the other axial side of the shaft; A resolver having a resolver rotor fixed to the shaft and a resolver stator fixed to the housing; A contact member having conductivity and being in contact with the shaft and electrically connected to the housing; The contact member includes a ring portion and a brush portion; The resolver, the first bearing, and the contact member are arranged side by side along the axial direction in the first housing, and are arranged in the order of the resolver, the first bearing, and the contact member from one axial side of the shaft toward the other axial side; The motor unit is such that the radially outer end of the first bearing is located radially inward of the radially outer end of the resolver and the radially outer end of the contact member.

3. The motor unit according to claim 1, further comprising a second seal member disposed between the contact member and the resolver in the axial direction and partitioning the contact member and the resolver.

4. The motor unit according to claim 2, further comprising a third seal member disposed on the other axial side of the contact member in the axial direction and between the contact member and the rotor.

5. The motor unit according to any one of claims 1 to 4, further comprising a first seal member disposed between the contact member and the first bearing in the axial direction and partitioning the contact member and the first bearing.

6. The motor unit according to any one of claims 1 to 5, further comprising a lubricant circulation section for circulating a lubricant for cooling the motor, wherein the housing stores the lubricant for cooling the motor therein.

7. The motor unit according to any one of claims 1 to 6, further comprising a bearing holder that is part of the housing, is disposed on one axial side of the rotor in the axial direction, and holds the first bearing. The contact member is fixed to the bearing holder.

8. The resolver stator is fixed to the bearing holder.

9. The contact member is fixed to the shaft.

10. The motor unit according to claim 7 or 8, further comprising a cover member attached to one axial side of the bearing holder, and wherein the contact member, the resolver, and the first bearing are disposed on the other axial side of the cover member in the axial direction.

11. The motor unit according to any one of claims 7, 8, and 10, wherein the bearing holder has a hole penetrating from one axial side to the other axial side of the bearing holder.

12. The ring portion is annular, and the brush portion is fixed to the inner peripheral surface of the ring portion and contacts the shaft.

13. The shaft is A first shaft through-hole that is disposed between the first bearing and the second bearing in the axial direction and penetrates the shaft in the radial direction; A second shaft through-hole that is disposed on one axial side of the first shaft through-hole and penetrates the shaft in the radial direction; and has The motor unit according to any one of claims 1 to 12, wherein a radially outer end portion of the second shaft through-hole is disposed on one axial side of the first bearing.

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