Drive device, vehicle

Abstract

To maintain good electric conductivity between a shaft and a housing.SOLUTION: A drive device includes: a first bearing which is lubricated by a fluid; and a second bearing which is lubricated by a lubricant having higher electric conductivity than that of the fluid. The first bearing rotatably supports a shaft 1 extending along a rotation axis J1 in an axial direction. A housing 4 of the drive device has a first bearing holder which holds the first bearing. The second bearing is disposed between the shaft 1 and the housing 4 and rotatably supports the shaft 1. The second bearing is disposed in a space isolated from the first bearing holder.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a drive device and a vehicle.

Background Art

[0002] Conventionally, a drive device having a charge removal mechanism on the shaft of a motor unit is known. For example, the rotating shaft of a rotating electrical machine is supported by a main bearing and an auxiliary bearing. The auxiliary bearing is filled with conductive grease. Thereby, when the shaft voltage of the rotating shaft tends to rise, the charge is caused to flow to the outer frame by the conductive grease of the auxiliary bearing and not to flow to the main bearing (see, for example, Japanese Patent Application Laid-Open No. 2000-316251).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when foreign matter adheres to the bearing as described above, there is a risk that it becomes difficult for the charge to flow to a housing such as the outer frame. For example, in an in-vehicle motor, lubricating oil, a refrigerant for cooling the motor unit, and the like circulate. If these adhere to the bearing having the above-described lubricant, there is a risk of mixing into the lubricant and increasing the electrical resistance of the lubricant. Therefore, it may become difficult to maintain good electrical conduction between the shaft and the housing.

[0005] An object of the present invention is to maintain good electrical conductivity between a shaft and a housing.

Means for Solving the Problems

[0006] An exemplary drive device of the present invention includes a shaft, a rotor, a stator, a first bearing, a housing, and a second bearing. The shaft extends axially along a rotation axis. The rotor is fixed to the shaft and is rotatable about the rotation axis. The stator faces the rotor with a radial gap therebetween. The first bearing rotatably supports the shaft and is lubricated by a fluid. The housing has a first bearing holder that holds the first bearing and houses the rotor and the stator. The second bearing is disposed between the shaft and the housing to rotatably support the shaft and is lubricated by a lubricant having a higher electrical conductivity than the fluid. The second bearing is disposed in a space isolated from the first bearing holder.

[0007] An exemplary vehicle of the present invention includes the above-described drive device.

Advantages of the Invention

[0008] According to the exemplary drive device and vehicle of the present invention, good electrical conductivity between the shaft and the housing can be maintained.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0010] Exemplary embodiments will be described below with reference to the drawings.

[0011] In this specification, the direction parallel to the rotation axis J1 of the motor unit 2 is defined as the "axial direction" of the drive device 100. Regarding the axial direction, as shown in FIG. 1, the motor unit 2 side is defined as one axial direction D1, and the gear unit 3 side is defined as the other axial direction D2. Further, the radial direction orthogonal to a predetermined axis such as the rotation axis J1 is simply referred to as the "radial direction", and the circumferential direction centered on a predetermined axis such as the rotation axis J1 is simply referred to as the "circumferential direction".

[0012] Also, in this specification, in the positional relationship between any one of a direction, a line, and a plane and any other one, "parallel" includes not only a state where the two do not intersect at all no matter how far they extend, but also a state where they are substantially parallel. Further, "perpendicular" includes not only a state where the two intersect at 90 degrees to each other, but also a state where they are substantially perpendicular. That is, "parallel" and "perpendicular" each include a state where there is an angular deviation within a range not departing from the gist of the present invention in the positional relationship between the two.

[0013] Also, in this specification, "extending" in a predetermined direction includes not only a configuration in which the extending direction strictly extends in the predetermined direction, but also a configuration in which it substantially extends in the predetermined direction. That is, "extending" in a predetermined direction includes a configuration in which there is a deviation in the direction within a range not departing from the gist of the present invention from the predetermined direction. The same applies to "spreading" in a predetermined direction.

[0014] <1. Embodiment> FIG. 1 is a conceptual diagram showing a configuration example of the drive device 100. FIG. 2 is a conceptual diagram showing an example of the shaft static elimination structure of the drive device 100 according to the embodiment. FIG. 3 is a schematic diagram showing an example of a vehicle 300 equipped with the drive device 100. Note that FIGS. 1 and 2 are merely conceptual diagrams, and the arrangement and dimensions of each part are not necessarily exactly the same as those of the actual drive device 100. Further, FIG. 2 is an enlarged view of the portion A surrounded by the broken line in FIG. 1. Also, FIG. 3 conceptually illustrates the vehicle 300.

[0015] As shown in FIG. 3 in this embodiment, the drive device 100 is mounted on a vehicle 300 that uses at least a motor as a power source, such as a hybrid vehicle (HV), a plug-in hybrid vehicle (PHV), or an electric vehicle (EV). The drive device 100 is used as a power source for the vehicle 300 described above. The vehicle 300 has the drive device 100. By mounting the drive device 100, the drive device 100 of the vehicle 300 including a charge removal mechanism between the shaft 1 and the housing 4 can be miniaturized. In FIG. 3, the drive device 100 drives the front wheels of the vehicle 300. Note that the drive device 100 may drive at least any one of the wheels. Further, the vehicle 300 further has a battery 200. The battery 200 stores electric power for supplying the drive device 100.

[0016] As shown in FIG. 1, the drive device 100 includes a shaft 1, a motor unit 2, a gear unit 3, a housing 4, a liquid circulation unit 5, a conductive bearing 6, a rotation detector 7, a first seal member 81, and a second seal member 82.

[0017] <1-1. Shaft 1> The shaft 1 extends in the axial direction along the rotation axis J1. As described above, the drive device 100 includes the shaft 1. The shaft 1 is rotatable about the rotation axis J1. As shown in FIG. 1, the shaft 1 is rotatably supported by the housing 4 via a first motor bearing 4211, a second motor bearing 4221, a third motor bearing 4311, and a fourth motor bearing 4611, which will be described later. That is, the drive device 100 includes these bearings 4211, 4221, 4311, and 4611. These bearings 4211, 4221, 4311, and 4611 rotatably support the shaft 1.

[0018] The shaft 1 is cylindrical and extends in the axial direction. Inside the shaft 1, a fluid F flows. The drive device 100 further includes this fluid F. In this embodiment, the fluid F is a lubricating fluid for lubricating the gear portion 3 and the bearings of the drive device 100, for example, ATF (automatic transmission fluid). Further, the fluid F is also used as a refrigerant for cooling the motor portion 2 and the like. In response to the rotation of the shaft 1, the fluid F flowing inside the shaft 1 can be supplied to the motor portion 2, the first motor bearing 4211, the third motor bearing 4311, etc. through a first shaft through hole 101 described later. Therefore, the fluid F can cool the stator 22 (particularly the coil end 2221 described later) and the above-described bearings 4211, 4311, etc.

[0019] Note that the shaft 1 may be dividable, for example, at an intermediate portion in the axial direction. When the shaft 1 is dividable, the divided shafts 1 are connected, for example, by spline fitting. Alternatively, they may be connected by a screw coupling using male and female threads, or may be joined by a fixing method such as press-fitting and welding. When adopting a fixing method such as press-fitting and welding, a serration combining concave and convex portions extending in the axial direction may be adopted. With such a configuration, it is possible to reliably transmit rotation.

[0020] <1-1-1. Shaft Cylindrical Portion 11 and Hollow Portion 12> The shaft 1 has a cylindrical shaft tube portion 11 that surrounds the rotation axis J1. The shaft tube portion 11 is cylindrical and extends axially along the rotation axis J1. The shaft tube portion 11 is rotatably supported by the third motor bearing 4311. Also, the shaft tube portion 11 is rotatably supported by the first motor bearing 4211, the second motor bearing 4221, the fourth motor bearing 4611, and the conduction bearing 6. The shaft tube portion 11 has conductivity and is made of metal in this embodiment. Further, the shaft 1 has a hollow portion 12 and an inlet 111. The hollow portion 12 is a space surrounded by the inner peripheral surface of the shaft tube portion 11 and is disposed inside the shaft tube portion 11. The inlet 111 is the other axial end of the cylindrical shaft tube portion 11 and is connected to the flow path 465 of the gear cover portion 46 described later. Through the inlet 111, the fluid F flows from the flow path 465 into the hollow portion 12.

[0021] <1-1-2. Shaft wall portion 13> Next, the shaft 1 further has a shaft wall portion 13. The shaft wall portion 13 is disposed inside the shaft tube portion 11 and extends radially. The shaft wall portion 13 is disposed on one axial side D1 of the shaft tube portion 11. Also, in this embodiment, the other axial end of the shaft wall portion 13 is disposed on the other axial side D2 than the rotation detector 7. The radially outer end of the shaft wall portion 13 is connected to the inner side surface of the shaft tube portion 11. Preferably, the shaft wall portion 13 is integral with the shaft tube portion 11. For example, the shaft wall portion 13 is a different part of the same member as the shaft tube portion 11 in this embodiment. By making the shaft wall portion 13 integral with the shaft tube portion 11, the shaft 1 becomes easier to manufacture. Also, the number of parts of the shaft 1 can be reduced, so the drive device 100 becomes easier to assemble. However, it is not limited to this example, and the shaft wall portion 13 may be a member different from the shaft tube portion 11.

[0022] At one axial end of the shaft 1, the shaft wall portion 13 forms a shaft recess 14 together with the shaft cylindrical portion 11. That is, the shaft 1 is provided with a shaft recess 14. The shaft recess 14 is recessed from one axial end of the shaft 1 in the other axial direction D2. In the present embodiment, the shaft recess 14 houses at least the other axial D2 side of the first columnar portion 442. Further, the shaft recess 14 houses the conduction bearing 6 and the first seal member 81.

[0023] <1-1-3. First Shaft Through-Hole 101> A first shaft through-hole 101 is arranged in the shaft cylindrical portion 11. That is, the shaft 1 further has a first shaft through-hole 101 that penetrates the shaft cylindrical portion 11 in the radial direction. The number of the first shaft through-holes 101 may be single or plural. When the shaft 1 rotates, the fluid F in the shaft cylindrical portion 11 flows out from the hollow portion 12 to the outside of the shaft cylindrical portion 11 through the first shaft through-hole 101 by centrifugal force. In the present embodiment, as shown in FIG. 1, the first shaft through-hole 101 is arranged in the one axial direction D1 from the other axial end of the rotor 21 and in the other axial direction D2 from the one axial end of the rotor 21, and is connected to a rotor through-hole 2111 described later. However, it is not limited to the example shown in FIG. 1, and the first shaft through-hole 101 may be arranged in the other axial direction D2 from the other axial end of the rotor 21 and in the one axial direction D1 from the first motor bearing 4211, or may be arranged in the one axial direction D1 from the one axial end of the rotor 21 and in the other axial direction D2 from the third motor bearing 4311. That is, at least a part of the first shaft through-holes 101 may be arranged at at least any one of these positions. Note that the above examples do not exclude a configuration in which the first shaft through-hole 101 and the rotor through-hole 2111 are omitted.

[0024] <1-1-4. Second Shaft Through-Hole 102> A second shaft through-hole 102 is disposed in the shaft cylindrical portion 11. The shaft 1 further has the second shaft through-hole 102. The second shaft through-hole 102 penetrates the shaft cylindrical portion 11 in the radial direction. Alternatively, the second shaft through-hole 102 may penetrate the shaft cylindrical portion 11 in a direction intersecting the radial direction and the axial direction. Note that the second shaft through-hole 102 is an example of the "shaft through-hole" of the present invention.

[0025] The number of the second shaft through-holes 102 may be singular or plural. In the latter case, the second shaft through-holes 102 can be arranged at equal or different intervals in the circumferential direction. Note that the above examples do not exclude a configuration in which the second shaft through-hole 102 is omitted.

[0026] In the present embodiment, the second shaft through-hole 102 is arranged in one axial direction D1 with respect to the first shaft through-hole 101 (see FIG. 1). The radially outer end portion of the second shaft through-hole 102 is connected to the third motor bearing holder 431. The radially inner end portion of the second shaft through-hole 102 is arranged in the other axial direction D2 with respect to the shaft wall portion 13 and is connected to the hollow portion 12. Here, the fluid F can flow through the inside of the shaft cylindrical portion 11. This fluid F is also supplied to the third motor bearing 4311 through the second shaft through-hole 102. For example, when the shaft 1 rotates, the fluid F flowing in the shaft cylindrical portion 11 flows into the second shaft through-hole 102 by centrifugal force. Therefore, for example, even without an EOP (electric oil pump), the fluid F can flow out from the second shaft through-hole 102 to the outside of the shaft 1. At least a part of the outflowing fluid F can be supplied to the third motor bearing 4311.

[0027] In addition, in the present embodiment, the other axial end of the shaft wall portion 13 is disposed on the other axial side D2 with respect to the one axial end of the opening 4312 of the third motor bearing holder 431 described later. Alternatively, the other axial end of the shaft wall portion 13 may be at the same axial position as the one axial end of the opening 4312. By doing so, the axial distance between the radially inner end of the second shaft through hole 102 and the shaft wall portion 13 can be made narrower. Therefore, for example, the fluid F flowing in the shaft cylinder portion 11 toward the one axial side D1 easily flows into the second shaft through hole 102, and less fluid F stays between the radially inner end of the second shaft through hole 102 and the shaft wall portion 13. Thus, the fluid F in the shaft cylinder portion 11 can be supplied to the third motor bearing 4311 more smoothly. However, the above example does not exclude the configuration in which the other axial end of the shaft wall portion 13 is disposed on the one axial side D1 with respect to the one axial end of the opening 4312.

[0028] The radially outer end of the second shaft through hole 102 is disposed on the one axial side D1 with respect to the third motor bearing 4311. Further preferably, the radially outer end of the second shaft through hole 102 is disposed on the other axial side D2 with respect to the one axial end of the opening 4312 of the housing lid portion 43 described later. More preferably, the radially outer end of the second shaft through hole 102 is disposed on the other axial side D2 with respect to the second seal member 82. Here, as described above, the radially outer end of the second shaft through hole 102 leads to the inside of the third motor bearing holder 431. Therefore, compared with the configuration in which the radially outer end of the second shaft through hole 102 is disposed on the one axial side D1 with respect to the one axial end of the opening 4312 (that is, the configuration in which the radially outer end of the second shaft through hole 102 leads to the outside of the third motor bearing holder 431), it is difficult for the fluid F to enter the space 403 described later where the one axial end of the shaft cylinder portion 11 is disposed. Therefore, it is possible to suppress the fluid F from acting on the rotation detector 7 and the conduction bearing 6 in the shaft recess 14. Note that the above example does not exclude the configuration in which the radially outer end of the second shaft through hole 102 is disposed on the one axial side D1 with respect to the one axial end of the opening 4312, nor does it exclude the configuration in which it is disposed on the one axial side D1 with respect to the second seal member 82.

[0029] <1-2. Motor unit 2> The motor unit 2 is a DC brushless motor. The motor unit 2 is a drive source of the drive device 100 and is driven by electric power from an inverter (not shown). The motor unit 2 is of an inner rotor type in which a rotor 21 is rotatably arranged inside a stator 22. As shown in FIG. 1, the motor unit 2 includes a rotor 21 and a stator 22.

[0030] <1-2-1. Rotor 21> The rotor 21 is supported by the shaft 1. The drive device 100 includes the rotor 21. The rotor 21 is fixed to the shaft 1 and is rotatable about the rotation axis J1. The rotor 21 rotates when electric power is supplied from a power supply unit (not shown) of the drive device 100 to the stator 22. The rotor 21 includes a rotor core 211 and magnets 212. The rotor core 211 is formed by laminating, for example, thin plate-shaped electromagnetic steel sheets. The rotor core 211 is a cylindrical body extending along the axial direction and is fixed to the radially outer surface of the shaft 1. A plurality of magnets 212 are fixed to the rotor core 211. The plurality of magnets 212 are arranged alternately with magnetic poles along the circumferential direction.

[0031] Further, the rotor core 211 has a rotor through hole 2111. The rotor through hole 2111 penetrates the rotor core 211 in the axial direction and is connected to the first shaft through hole 101. The rotor through hole 2111 is used as a flow path for a fluid F that also functions as a refrigerant. When the rotor 21 rotates, the fluid F flowing through the hollow portion 12 of the shaft 1 can flow into the rotor through hole 2111 via the first shaft through hole 101. Also, the fluid F that has flowed into the rotor through hole 2111 can flow out to the outside from both axial ends of the rotor through hole 2111. The fluid F that has flowed out jumps toward the stator 22 and cools, for example, the coil portion 222 (especially the coil end 2221). Also, the fluid F that has flowed out jumps toward the first motor bearing 4211 and the third motor bearing 4311 that rotatably support the shaft 1, lubricating and cooling these bearings 4211, 4311.

[0032] <1-2-2. Stator 22> The stator 22 faces the rotor 21 with a radial gap therebetween. The drive device 100 includes the stator 22. The stator 22 is disposed radially outward of the rotor 21. The stator 22 has a stator core 221 and a coil portion 222. The stator 22 is held by a first housing cylinder portion 41 described later. The stator core 221 has a plurality of magnetic pole teeth (not shown) extending radially inward from the inner peripheral surface of an annular yoke. The coil portion 222 is formed by winding a conducting wire around the magnetic pole teeth via an insulator (not shown). The coil portion 222 has a coil end 2221 protruding from the axial end surface of the stator core 221.

[0033] <1-3. Gear portion 3> Next, the gear portion 3 is a power transmission device that transmits the power of the motor portion 2 to a drive shaft Ds described later. The gear portion 3 has a speed reduction device 31 and a differential device 32.

[0034] <1-3-1. Speed reduction device 31> The speed reduction device 31 is connected to the shaft 1. The speed reduction device 31 has a function of reducing the rotational speed of the motor portion 2 and increasing the torque output from the motor portion 2 according to the reduction ratio. The speed reduction device 31 transmits the torque output from the motor portion 2 to the differential device 32. That is, the gear portion 3 is connected to one D1 side in the axial direction of the shaft 1 that rotates about a rotation axis J1 extending along the horizontal direction.

[0035] The speed reduction device 31 has a main drive gear 311, an intermediate driven gear 312, a final drive gear 313, and an intermediate shaft 314. The torque output from the motor portion 2 is transmitted to the ring gear 321 of the differential device 32 via the shaft 1, the main drive gear 311, the intermediate driven gear 312, the intermediate shaft 314, and the final drive gear 313.

[0036] The main drive gear 311 is arranged on the outer peripheral surface of the shaft 1. The main drive gear 311 may be the same member as the shaft 1, or may be another member firmly fixed thereto. The main drive gear 311 rotates about the rotation axis J1 together with the shaft 1.

[0037] The intermediate shaft 314 extends along an intermediate axis J2 parallel to the rotation axis J1. Both ends of the intermediate shaft 314 are rotatably supported about the intermediate axis J2 by a first intermediate bearing 4231 and a second intermediate bearing 4621. The intermediate driven gear 312 and the final drive gear 313 are arranged on the outer peripheral surface of the intermediate shaft 314. The intermediate driven gear 312 may be the same member as the intermediate shaft 314, or may be another member firmly fixed thereto.

[0038] The intermediate driven gear 312 and the final drive gear 313 rotate integrally with the intermediate shaft 314 about the intermediate axis J2. The intermediate driven gear 312 meshes with the main drive gear 311. The final drive gear 313 meshes with the ring gear 321 of the differential device 32.

[0039] The torque of the shaft 1 is transmitted from the main drive gear 311 to the intermediate driven gear 312. Then, the torque transmitted to the intermediate driven gear 312 is transmitted to the final drive gear 313 via the intermediate shaft 314. Further, torque is transmitted from the final drive gear 313 to the ring gear 321.

[0040] <1-3-2. Differential device 32> The differential device 32 is attached to the drive shaft Ds. The differential device 32 has a ring gear 321. The ring gear 321 transmits the torque transmitted from the speed reduction device 31 to the drive shaft Ds. The drive shaft Ds is attached to the other axial direction D2 and one axial direction D1 of the differential device 32, respectively. The drive shaft Ds1 on the one axial direction D1 side is rotatably supported by a first output bearing 4241 described later. The drive shaft Ds2 on the other axial direction D2 side is rotatably supported by a second output bearing 4631 described later. The differential device 32 transmits torque to the drive shafts Ds1 and Ds2 on both axial sides while absorbing the rotational speed difference between the drive shafts Ds1 and Ds2 on both axial sides, for example, when the vehicle turns.

[0041] The lower end portion of the ring gear 321 is disposed inside a liquid storage portion P described later where the fluid F stored in the lower part of the gear portion accommodation space 402 accumulates (see FIG. 1). Therefore, when the first gear 331 rotates, the fluid F is scraped up by the gear teeth of the ring gear 321. The gears and bearings of the gear portion 3 are lubricated or cooled by the fluid F scraped up by the ring gear 321. Also, a part of the scraped-up fluid F is stored in a tray portion 464 described later and is also used for cooling the motor portion 2 via the shaft 1.

[0042] <1-4. Housing 4> The housing 4 houses the shaft 1, the motor portion 2, and the gear portion 3. The housing 4 has a first housing cylinder portion 41, a side plate portion 42, a housing lid portion 43, a cover member 44, a second housing cylinder portion 45, and a gear lid portion 46. Note that the first housing cylinder portion 41, the side plate portion 42, the housing lid portion 43, the cover member 44, the second housing cylinder portion 45, and the gear lid portion 46 are formed using, for example, a conductive material, and in the present embodiment, are formed using a metal material such as iron, aluminum, or an alloy thereof. Also, in order to suppress dissimilar metal contact corrosion at the contact portions, these are preferably formed using the same material. However, the present invention is not limited to this example, and these may be formed using a material other than a metal material, or at least a part of these may be formed using a different material.

[0043] Further, the housing 4 houses the rotor 21 and the stator 22. The housing 4 also has a third motor bearing holder 431 that holds the third motor bearing 4311. Note that the third motor bearing holder 431 is an example of the "first bearing holder" of the present invention. As described above, the drive device 100 includes the housing 4. Specifically, the housing 4 has a motor accommodation space 401. The motor accommodation space 401 is a space surrounded by the first housing cylindrical portion 41, the side plate portion 42, and the housing lid portion 43, and houses the rotor 21, the stator 22, the first motor bearing 4211, the third motor bearing 4311, and the like.

[0044] Also, as described above, the housing 4 houses the gear unit 3. Specifically, the housing 4 has a gear unit accommodation space 402. The gear unit accommodation space 402 is a space surrounded by the side plate portion 42, the second housing cylindrical portion 45, and the gear lid portion 46, and houses the reduction gear device 31 and the differential device 32 and the like.

[0045] At the lower part inside the gear unit accommodation space 402, a liquid storage portion P where the fluid F accumulates is arranged. A part of the differential device 32 is immersed in the liquid storage portion P. The fluid F accumulated in the liquid storage portion P is scraped up by the operation of the differential device 32 and supplied into the gear unit accommodation space 402. For example, when the ring gear 321 of the differential device 32 rotates, the fluid F is scraped up by the tooth surface of the ring gear 321. A part of the scraped-up fluid F is supplied to each gear and each bearing of the reduction gear device 31 and the differential device 32 in the gear unit accommodation space 402 and used for lubrication. Another part of the scraped-up fluid F is supplied into the inside of the shaft 1 and supplied to the rotor 21 and the stator 22 of the motor unit 2 and each bearing in the gear unit accommodation space 402 and used for cooling and lubrication.

[0046] <1-4-1. First housing cylindrical portion 41> The first housing cylinder part 41 is cylindrical and extends in the axial direction, surrounding the rotation axis J1. The first housing cylinder part 41 is an example of the "housing cylinder part" of the present invention. As described above, the housing 4 has the first housing cylinder part 41. Inside the first housing cylinder part 41, a motor part 2, a fluid reservoir 54 to be described later, etc. are arranged. Also, a stator core 221 is fixed to the inner surface of the first housing cylinder part 41.

[0047] <1-4-2. Side plate part 42> The side plate part 42 covers the other axial end of the first housing cylinder part 41 and also covers one axial end of the second housing cylinder part 45. The side plate part 42 extends in a direction intersecting the rotation axis J1 and partitions the first housing cylinder part 41 and the second housing cylinder part 45. In the present embodiment, the first housing cylinder part 41 and the side plate part 42 are different parts of a single member. By integrally forming these, their rigidity can be enhanced. However, it is not limited to this example, and the two may be separate members.

[0048] The side plate part 42 has a side plate through-hole 4201 through which the shaft 1 is inserted and a first drive shaft through-hole 4202. The side plate through-hole 4201 and the first drive shaft through-hole 4202 penetrate the side plate part 42 in the axial direction. The center of the side plate through-hole 4201 coincides with the rotation axis J1. The shaft 1 is inserted into the side plate through-hole 4201. The center of the first drive shaft through-hole 4202 coincides with the drive shaft J3. A drive shaft Ds1 on one axial side D1 is inserted into the first drive shaft through-hole 4202. An oil seal (not shown) for sealing between the two is arranged in the gap between the drive shaft Ds1 and the first drive shaft through-hole 4202.

[0049] In addition, the side plate portion 42 further includes a first motor bearing holder 421, a second motor bearing holder 422, a first intermediate bearing holder 423, and a first output bearing holder 424. The first motor bearing holder 421 is disposed on one axial side D1 of the side plate through hole 4201 in the side plate portion 42 and holds the first motor bearing 4211. The second motor bearing holder 422 is disposed along the outer edge portion of the other axial end of the side plate through hole 4201 and holds the second motor bearing 4221. The first intermediate bearing holder 423 is disposed on the other axial end face of the side plate portion 42 and holds the first intermediate bearing 4231. The first output bearing holder 424 is disposed along the outer edge portion of the other axial end of the first drive shaft through hole 4202 in the side plate portion 42 and holds the first output bearing 4241. The first motor bearing 4211, the second motor bearing 4221, the first intermediate bearing 4231, and the first output bearing 4241 are ball bearings in this embodiment.

[0050] <1-4-3. Housing lid portion 43> The housing lid portion 43 extends in a direction intersecting the rotation axis J1 and covers one axial end of the first housing cylindrical portion 41. As described above, the housing 4 has the housing lid portion 43. The housing lid portion 43 is disposed and attached to one axial end of the first housing cylindrical portion 41. The fixing of the housing lid portion 43 to the first housing cylindrical portion 41 can be, for example, fixing by screws, but is not limited thereto, and methods that can firmly fix the housing lid portion 43 to the first housing cylindrical portion 41, such as screwing in and press-fitting, can be widely adopted. Thereby, the housing lid portion 43 can be in close contact with one axial end of the first housing cylindrical portion 41. Note that close contact means having a sealing property such that the fluid F inside the member does not leak to the outside and foreign matters such as external water, dust, and dirt do not enter. The same applies hereinafter for close contact.

[0051] Further, the housing lid portion 43 has a third motor bearing holder 431. In other words, the drive device 100 includes the third motor bearing holder 431. The third motor bearing holder 431 is disposed on the other end face in the axial direction of the housing lid portion 43. The third motor bearing holder 431 holds a third motor bearing 4311. The drive device 100 includes the third motor bearing 4311. The third motor bearing 4311 rotatably supports the shaft 1 and is lubricated by the fluid F. The third motor bearing 4311 is an example of the "first bearing" of the present invention and is a ball bearing in this embodiment.

[0052] The third motor bearing holder 431 has an opening 4312 through which the shaft 1 is inserted. In other words, the housing lid portion 43 has an opening 4312 through which the shaft 1 is inserted. The opening 4312 penetrates the housing lid portion 43 in the axial direction and surrounds the rotation axis J1 when viewed from the axial direction.

[0053] Further, the housing lid portion 43 further has a detector holder 432 that holds the rotation detector 7. In this embodiment, the detector holder 432 is a step disposed on one D1 side in the axial direction of the housing lid portion 43. This step is annular and surrounds the rotation axis J1.

[0054] <1-4-4. Cover member 44> The cover member 44 is disposed on one end face in the axial direction of the housing lid portion 43 and covers the opening 4321. As described above, the housing 4 has the cover member 44. The attachment of the cover member 44 to the housing lid portion 43 can be, for example, screwing, but is not limited thereto, and a method capable of firmly fixing the cover member 44 to the housing lid portion 43, such as screwing in or press-fitting, can be widely adopted. In this embodiment, the cover member 44 forms a space 403 together with the housing lid portion 43. The space 403 is a space surrounded by the housing lid portion 43 and the cover member 44 and houses one end portion in the axial direction of the shaft 1, the rotation detector 7, the second seal member 82, and the like.

[0055] The cover member 44 has a plate portion 441 and a first columnar portion 442. The plate portion 441 is plate-shaped and extends in a direction intersecting the rotation axis J1. In this embodiment, it extends radially from the rotation axis J1. The plate portion 441 is disposed in one axial direction D1 from one axial end of the shaft 1 and covers the opening 4312 and one axial end of the shaft 1. The first columnar portion 442 extends axially along the rotation axis J1. The housing 4 has the first columnar portion 442. Specifically, the first columnar portion 442 extends from the plate portion 441 in the other axial direction D2. When viewed axially, the center of the first columnar portion 442 coincides with the rotation axis J1. The other axial D2 side of the first columnar portion 442 is accommodated in the hollow portion 12 at one axial end of the shaft cylinder portion 11.

[0056] <1-4-5. Second housing cylinder portion 45> The second housing cylinder portion 45 is cylindrical and surrounds the rotation axis J1 and extends axially. One axial end of the second housing cylinder portion 45 is connected to the side plate portion 42 and covered by the side plate portion 42. In this embodiment, the second housing cylinder portion 45 is detachably attached to the other axial end of the side plate portion 42. Also, the attachment of the second housing cylinder portion 45 to the side plate portion 42 can be, for example, fixing by screws, but is not limited to this, and methods such as screwing in and press-fitting that can firmly fix the second housing cylinder portion 45 to the side plate portion 42 can be widely adopted. Thereby, the second housing cylinder portion 45 can be in close contact with the other axial end of the side plate portion 42.

[0057] <1-4-6. Gear cover portion 46> The gear cover portion 46 extends in a direction intersecting the rotation axis J1. The gear portion 3 is disposed inside the second housing cylinder portion 45 and the gear cover portion 46. In this embodiment, the second housing cylinder portion 45 and the gear cover portion 46 are different parts of a single member. However, it is not limited to this example, and the second housing cylinder portion 45 and the gear cover portion 46 may be separate members.

[0058] The gear cover portion 46 has a second drive shaft through hole 460. The center of the second drive shaft through hole 460 coincides with the drive shaft J3. A drive shaft Ds is inserted into the second drive shaft through hole 460. An oil seal (not shown) is disposed in the gap between the drive shaft Ds on the other axial side D2 and the second drive shaft through hole 460.

[0059] Further, the gear cover portion 46 further has a fourth motor bearing holder 461, a second intermediate bearing holder 462, and a second output bearing holder 463. These bearing holders 461, 462, 463 are disposed on one axial end surface of the gear cover portion 46 in the gear portion accommodation space 402. The fourth motor bearing holder 461 and the second intermediate bearing holder 462 are disposed on one axial end surface of the gear cover portion 46. The fourth motor bearing holder 461 holds a fourth motor bearing 4611. The second intermediate bearing holder 462 holds a second intermediate bearing 4621. The second output bearing holder 463 is disposed along the outer edge portion of one axial end of the second drive shaft through hole 460 in the gear cover portion 46 and holds a second output bearing 4631. The fourth motor bearing 4611, the second intermediate bearing 4621, and the second output bearing 4631 are ball bearings in the present embodiment.

[0060] Further, the gear cover portion 46 has a saucer portion 464 and a flow path 465. The saucer portion 464 is disposed on one axial end surface of the gear cover portion 46 and has a recess that is recessed vertically downward. The saucer portion 464 can store the fluid F scraped up by the ring gear 321. The flow path 465 is a passage for the fluid F and connects the saucer portion 464 and the inlet 111 of the shaft 1. The fluid F stored in the saucer portion 464 is supplied to the flow path 465 and flows into the hollow portion 12 from the inlet 111 at the other axial end of the shaft 1.

[0061] <1-5. Liquid circulation unit 5> Next, the liquid circulation unit 5 will be described. The liquid circulation unit 5 has a piping unit 51, a pump 52, a cooler unit 53, and a fluid reservoir 54.

[0062] The piping section 51 connects the pump 52 and the fluid reservoir 54 disposed inside the first housing cylinder section 41, and supplies the fluid F to the fluid reservoir 54. The pump 52 sucks in the fluid F stored in the lower region of the gear section accommodation space 402. The pump 52 is an electric pump, but is not limited thereto. For example, it may be configured to be driven by using a part of the power of the shaft 1 of the drive device 100.

[0063] The cooler unit 53 is disposed between the pump 52 and the fluid reservoir 54 in the piping section 51. That is, the fluid F sucked by the pump 52 passes through the cooler unit 53 via the piping section 51 and then is sent to the fluid reservoir 54. A refrigerant such as water supplied from the outside is supplied to the cooler unit 53. The cooler unit 53 exchanges heat between the refrigerant and the fluid F to lower the temperature of the fluid F.

[0064] The fluid reservoir 54 is a tray disposed vertically above the stator 22 inside the motor accommodation space 401. A dropping hole (reference numeral omitted) is formed at the bottom of the fluid reservoir 54, and the fluid F is dropped from the dropping hole to cool the motor section 2. The dropping hole is formed, for example, above the coil end 2221 of the coil section 222 of the stator 22, and the coil section 222 is cooled by the fluid F.

[0065] <1-6. Conductive bearing 6> Next, the conductive bearing 6 will be described. The conductive bearing 6 is disposed between the shaft 1 and the housing 4 and rotatably supports the shaft 1. As described above, the drive device 100 includes the conductive bearing 6. The conductive bearing 6 is an example of the "second bearing" of the present invention in the present embodiment, and is a ball bearing in the present embodiment.

[0066] The conductive bearing 6 is lubricated by a lubricant 61 having a higher electrical conductivity than the fluid F. In the present embodiment, conductive grease is used as the lubricant 61. In the conductive grease, conductive materials such as copper powder and carbon powder are added to a lubricating oil such as grease. The conductive bearing 6 can electrically connect the shaft cylinder portion 11 and the first columnar portion 442 by the lubricant 61. For example, since the inner ring and the outer ring of the ball bearing are electrically connected by the lubricant 61, the shaft cylinder portion 11 is electrically connected to the first columnar portion 442 of the housing 4.

[0067] The conductive bearing 6 is disposed in a space isolated from the third motor bearing holder 431. In the present embodiment, this space is the shaft recess 14. For example, the third motor bearing 4311 is lubricated by a fluid F having electrical insulation properties such as ATF (automatic transmission fluid), so that while ensuring the lubricity of the third motor bearing 4311, the shaft 1 and the housing 4 can be electrically insulated in the third motor bearing 4311. For example, if the third motor bearing 4311 is a ball bearing, insulation can be achieved between the outer ring fixed to one of the shaft 1 and the housing 4 and the inner ring fixed to the other of the shaft 1 and the housing 4. Further, the conductive bearing 6 is disposed between the shaft 1 and the housing 4 and is lubricated by a lubricant 61 having electrical conductivity. Since this conductive bearing 6 is disposed in a space (shaft recess 14 in the present embodiment) isolated from the third motor bearing holder 431, it is difficult for the fluid F that lubricates and cools the stator 22 and the third motor bearing 4311 to act on the conductive bearing 6. Therefore, it is possible to prevent the fluid F from mixing into the lubricant 61, and thus it is possible to prevent a decrease in the electrical conductivity of the lubricant 61. Therefore, the conductive bearing 6 can maintain a good electrical connection with the shaft 1 and the first columnar portion 442 of the housing 4. Therefore, through the conductive bearing 6, the current generated by the potential fluctuation occurring in the shaft 1 can be sufficiently discharged to the housing 4.

[0068] The conduction bearing 6 is arranged coaxially with the third motor bearing 4311. For example, both are annular about the same axis (i.e., the rotation axis J1). In this way, the conduction bearing 6 and the third motor bearing 4311 can support the shaft 1 more stably in a rotatable manner.

[0069] In this embodiment, the conduction bearing 6 fits into the shaft recess 14. For example, the radially outer end portion (e.g., the outer ring of the ball bearing) of the conduction bearing 6 fits into and contacts the inner peripheral surface of the shaft recess 14. The radially inner end portion (e.g., the inner ring of the ball bearing) of the conduction bearing 6 contacts the radially outer surface of the first columnar portion 442. In this way, since the conduction bearing 6 fits into and is held by the shaft recess 14, there is no need to secure a space for arranging the conduction bearing 6 and a bearing holder for holding the conduction bearing 6 outside the shaft 1. Therefore, the drive device 100 can be miniaturized. However, it is not limited to this example, and the conduction bearing 6 may be fixed to the shaft recess 14 by means other than the fitting structure as described above (such as welding, brazing, etc.).

[0070] The conduction bearing 6 is arranged on one axial side D1 of the shaft wall portion 13 rather than on the other axial side D2 inside the shaft cylinder portion 11. The second shaft through-hole 102 is arranged on the other axial side D2 of the shaft wall portion 13. In this way, the shaft wall portion 13 can isolate the space through which the fluid F flows in the shaft cylinder portion 11 from the space where the conduction bearing 6 is arranged. For example, the hollow portion 12 in the shaft cylinder portion 11 can be partitioned into the other axial side D2 side of the shaft wall portion 13 of the hollow portion 12 and the shaft recess 14. The fluid F flows in the former, and the conduction bearing 6 is arranged in the latter. Therefore, the fluid F can be prevented from directly acting on the conduction bearing 6.

[0071] <1-7. Rotation detector 7> The rotation detector 7 is attached to one axial side D1 of the housing lid portion 43. The rotation detector 7 is disposed on one axial side D1 of the third motor bearing holder 431 and detects the rotation angle of the shaft 1. In this embodiment, the rotation detector 7 is a resolver having a resolver rotor and a resolver stator. The rotation detector 7 has a resolver rotor (not shown) fixed to the shaft 1 and a resolver stator (not shown) fixed to the housing lid portion 43 of the housing 4. The resolver rotor and the resolver stator are annular. The inner peripheral surface of the resolver stator faces the outer peripheral surface of the resolver rotor in the radial direction. The resolver stator periodically detects the rotation angle position of the resolver rotor when the rotor 21 rotates. Thereby, the rotation detector 7 acquires information on the rotation angle position of the rotor 21. Note that the rotation detector 7 is not limited to the example of this embodiment and may not be a resolver, for example, a rotary encoder or the like.

[0072] <1-8. The first seal member 81> The first seal member 81 is disposed on one axial side D1 of the conduction bearing 6 within the shaft cylinder portion 11. In this embodiment, the shaft 1 has the first seal member 81. The first seal member 81 is annular and surrounds the rotation axis J1. In this embodiment, the first seal member 81 is fixed to the radially outer surface of the first columnar portion 442 and spreads outward in the radial direction (see FIG. 2). However, it is not limited to this example, and the first seal member 81 may be fixed to the inner peripheral surface of the shaft cylinder portion 11 and spread inward in the radial direction. That is, the first seal member 81 may be fixed to either the inner peripheral surface of the shaft cylinder portion 11 or the radially outer surface of the first columnar portion 442, and may spread from one of the above in the radial direction toward the other.

[0073] By doing so, at a position on the one axial direction D1 side of the conduction bearing 6 in the shaft cylinder portion 11, the gap between the inner peripheral surface of the shaft cylinder portion 11 and the radially outer surface of the first columnar portion 442 can be covered by the first seal member 81 that spreads radially. Here, at one axial end of the shaft 1, for example, mist of the fluid F for lubricating and cooling each part of the drive device 100 may enter the shaft cylinder portion 11. Even if such an intrusion of the fluid F occurs, the intrusion of the fluid F from the one axial direction D1 side to the other axial direction D2 side of the first seal member 81 can be suppressed or prevented. Therefore, it is possible to effectively suppress or prevent the fluid F from being applied to the conduction bearing 6.

[0074] In the present embodiment, the first seal member 81 is a slinger having a fixing portion (reference numeral omitted) and a flange portion (reference numeral omitted). The fixing portion of the slinger is a cylindrical shape extending in the axial direction. The flange portion is a plate shape spreading radially from the fixing portion and covers the gap between the shaft cylinder portion 11 and the first columnar portion 442 in the radial direction. However, the first seal member 81 is not limited to this example. An oil seal, a mechanical seal, packing, or the like may be used for the first seal member 81.

[0075] <1-9. Second seal member 82> The second seal member 82 is disposed radially outward of the shaft 1. As described above, the drive device 100 further includes the second seal member 82. The second seal member 82 is disposed between the third motor bearing 4311 and one axial end of the shaft 1 in the axial direction. Specifically, the second seal member 82 is annular and surrounds the rotation axis J1, and covers the gap between the shaft 1 and the housing lid portion 43 (in other words, the inner peripheral surface of the opening 4312). By doing so, by partitioning the third motor bearing holder 431 with the second seal member 82, it is possible to suppress or prevent the fluid F for lubricating the third motor bearing 4311 from being applied to the conduction bearing 6. Therefore, a decrease in electrical conductivity in the conduction bearing 6 can be suppressed.

[0076] Preferably, the second seal member 82 is disposed axially between the third motor bearing 4311 and the rotation detector 7. The second seal member 82 partitions the third motor bearing holder 431 and the space 403 in which the rotation detector 7 is disposed. In this way, the second seal member 82 can suppress or prevent the fluid F lubricating the third motor bearing 4311 from reaching the rotation detector 7. Note that this illustration does not exclude the configuration in which the second seal member 82 is disposed on one axial side D1 of the rotation detector 7.

[0077] In the present embodiment, the second seal member 82 is disposed outside thereof at one axial end of the opening 4312. However, the arrangement of the second seal member 82 is not limited to the example of the present embodiment. For example, the second seal member 82 may be disposed inside the opening 4312. Further, preferably, the second seal member 82 is disposed on one axial side D1 of the outer end in the radial direction of the second shaft through hole 102. In this way, it is possible to suppress or prevent the fluid F flowing out from the second shaft through hole 102 from reaching the rotation detector 7. Note that this illustration does not exclude the configuration in which the second seal member 82 is disposed on the other axial side D2 of the outer end in the radial direction of the second shaft through hole 102.

[0078] In the present embodiment, the second seal member 82 is a slinger having a fixing portion (reference numeral omitted) and a flange portion (reference numeral omitted). The fixing portion of the slinger is a cylindrical shape extending in the axial direction. The flange portion is a plate shape extending radially from the fixing portion, and covers the gap between the shaft cylindrical portion 11 and the housing lid portion 43 (inner peripheral surface of the opening 4312) in the radial direction. However, the second seal member 82 is not limited to this example. An oil seal, a mechanical seal, packing, or the like may be used for the second seal member 82. Alternatively, the second seal member 82 may be a part of the third motor bearing 4311. That is, the third motor bearing 4311 may be a sealed ball bearing including the second seal member 82. Or, the second seal member 82 may be a part of the conductive bearing 6. That is, the conductive bearing 6 may be a sealed ball bearing including the second seal member 82 and the lubricant 61.

[0079] <2. First Modified Example> Next, with reference to FIGS. 4 and 5, a first modified example of the embodiment will be described. FIG. 4 is a conceptual diagram showing an example of a shaft static elimination structure according to the first modified example. FIG. 5 is a conceptual diagram showing another example of the shaft static elimination structure according to the first modified example. Note that FIGS. 4 and 5 are merely conceptual diagrams, and the arrangement and dimensions of each part are not necessarily exactly the same as those of the actual drive device 100. Also, FIGS. 4 and 5 correspond to the portion A surrounded by the broken line in FIG. 1. Hereinafter, configurations different from the above-described embodiment will be described. Also, the same reference numerals are given to the same components as those in the above-described embodiment, and the description thereof may be omitted.

[0080] In the first modified example, the drive device 100 includes a second columnar portion 15, a conduction bearing holder 443, and a conduction bearing 4431 instead of the first columnar portion 442 and the conduction bearing 6 (see FIG. 2). Specifically, the shaft 1 has a second columnar portion 15. The second columnar portion 15 extends in the axial direction one D1 along the rotation axis J1 from the shaft wall portion 13. When viewed from the axial direction, the center of the second columnar portion 15 coincides with the rotation axis J1. The axial direction one D1 side of the second columnar portion 15 is accommodated in the conduction bearing holder 443. The cover member 44 has a plate portion 441. The cover member 44 further has a conduction bearing holder 443 that holds the conduction bearing 4431. The conduction bearing 4431 rotatably supports the second columnar portion 15. The conduction bearing 4431 is an example of the "second bearing" of the present invention in the first modified example, and is a ball bearing having the same configuration as the conduction bearing of the embodiment. For example, the conduction bearing 4431 is lubricated by a lubricant 4432 having higher electrical conductivity than the fluid F. The conduction bearing holder 443 is disposed on the other axial end face of the plate portion 441. When viewed from the axial direction, the center of the conduction bearing holder 443 coincides with the rotation axis J1.

[0081] According to the first modification example, the shaft wall portion 13 can isolate the space in the shaft cylinder portion 11 through which the fluid F flows from the space 403 in which the conduction bearing 4431 is disposed. Note that the former space is the hollow portion 12 in FIG. 4 and is on the other axial side D2 of the shaft wall portion 13 of the hollow portion 12 in FIG. 5. For example, by closing one axial end portion of the shaft cylinder portion 11 with the shaft wall portion 13, it is possible to prevent the fluid F from flowing out of the shaft 1 from one axial end portion of the shaft cylinder portion 11. Therefore, it is possible to prevent the fluid F from being applied to the conduction bearing 4431.

[0082] Further, since the conduction bearing 4431 that rotatably supports the second columnar portion 15 is held by the conduction bearing holder 443 of the cover member 44, the current generated by the potential fluctuation generated in the shaft 1 can be discharged to the cover member 44 of the housing 4 through the second columnar portion 15, the conduction bearing 4431, and the conduction bearing holder 443.

[0083] Note that in FIG. 4, the shaft wall portion 13 is disposed at one axial end portion of the shaft cylinder portion 11. Therefore, the shaft 1 does not have the shaft recess 14 (see FIG. 2). However, the present invention is not limited to the example shown in FIG. 4, and the shaft 1 may have the shaft recess 14. For example, as shown in FIG. 5, the shaft wall portion 13 may be disposed on the other axial side D2 of the shaft cylinder portion 11 rather than at one axial end portion of the shaft cylinder portion 11 on one axial side D1 of the shaft cylinder portion 11. Further, at least the other axial side D2 of the conduction bearing holder 443 may be housed inside the shaft cylinder portion 11, and in FIG. 5, it is housed in the shaft recess 14. In this way, it is not necessary to secure a space for disposing the conduction bearing 4431 and the conduction bearing holder 443 outside the shaft 1 (particularly on one axial side D1 of the shaft cylinder portion 11). Therefore, an increase in the axial size of the drive device 100 can be suppressed, which contributes to the miniaturization of the drive device 100.

[0084] <3. Second Modification Example> Next, referring to FIG. 6, a second modification of the embodiment will be described. FIG. 6 is a conceptual diagram showing an example of a shaft static elimination structure according to the second modification. Note that FIG. 6 is merely a conceptual diagram, and the arrangement and dimensions of each part are not necessarily exactly the same as those of the actual drive device 100. Also, FIG. 6 corresponds to the portion A surrounded by the dashed line in FIG. 1. Hereinafter, configurations different from the above-described embodiment and the first modification will be described. Also, the same reference numerals are given to the same components as those in the above-described embodiment and the first modification, and the description thereof may be omitted.

[0085] In the second modification, unlike the first modification, the drive device 100 includes a conductive bearing 4331 and a conductive bearing holder 433 instead of the first columnar portion 442 and the conductive bearing 6 (see FIG. 2) of the embodiment, the second columnar portion 15 of the first modification, the conductive bearing holder 443, and the conductive bearing 4431 (see FIGS. 4 and 5). Specifically, the conductive bearing 4331 is arranged on the radially outer surface of the shaft 1 together with the third motor bearing 4311. In the second modification, the conductive bearing 4331 is an example of the "second bearing" of the present invention and is a ball bearing having the same configuration as the conductive bearing 6 of the embodiment. For example, the conductive bearing 4331 is lubricated by a lubricant 4332 having higher electrical conductivity than the fluid F. The conductive bearing 4331 is arranged on one axial side D1 with respect to the third motor bearing 4311. Also, the conductive bearing holder 433 holds the conductive bearing 4331. The housing 4 further includes the conductive bearing holder 433. In the second modification, the conductive bearing holder 433 is an example of the "second bearing holder" of the present invention. When viewed from the axial direction, the center of the conductive bearing holder 443 coincides with the rotation axis J1.

[0086] In FIG. 6, the conductive bearing 4331 is disposed on one axial side D1 of the opening 4312. The radially inner end portion (for example, the inner ring) of the conductive bearing 4331 is fixed to the outer peripheral surface of the shaft cylinder portion 11. The radially outer end portion (for example, the outer ring) of the conductive bearing 4331 is fixed to the inner peripheral surface of the opening 4312 of the housing lid portion 43. That is, in FIG. 6, the conductive bearing holder 433 is a portion along the outer edge of one axial end portion of the opening 4312 of the housing lid portion 43. However, the present invention is not limited to the example shown in FIG. 6, and outside the opening 4312, the conductive bearing holder 433 may be disposed on one axial end surface of the housing lid portion 43.

[0087] In the second modification, preferably as shown in FIG. 6, the second seal member 82 is disposed axially between the third motor bearing 4311 and the conductive bearing 4331 to partition the third motor bearing holder 431 and the conductive bearing holder 433. By doing so, by partitioning the third motor bearing holder 431 and the conductive bearing holder 433 with the second seal member 82, it is possible to suppress or prevent the fluid F for lubricating the third motor bearing holder 431 from reaching the conductive bearing holder 433. Therefore, a decrease in electrical conductivity in the conductive bearing holder 433 can be suppressed. Further, since the third motor bearing holder 431 and the conductive bearing holder 433 are disposed on the radially outer side surface of the shaft 1, the conductive bearing holder 433 having electrical conductivity can be disposed near the third motor bearing 4311. Therefore, electrical conduction in the third motor bearing holder 431 lubricated by the fluid F having electrical insulation can be more effectively suppressed or prevented. For example, it is possible to effectively suppress or prevent discharge between the inner ring and the outer ring of the ball bearing.

[0088] <4. Others> The embodiments of the present invention have been described above. Note that the scope of the present invention is not limited to the above-described embodiments. The present invention can be implemented by making various modifications to the above-described embodiments without departing from the gist of the invention. In addition, the matters described in the above-described embodiments can be arbitrarily combined as appropriate without causing contradictions.

Industrial Applicability

[0089] The present invention is useful for a device that grounds a rotatable shaft. Further, the present invention is useful for a motor mounted on a vehicle, but is also useful for motors used in applications other than in-vehicle use.

Explanation of Signs

[0090] 100 ··· drive device, 200 ··· battery, 300 ··· vehicle, 1 ··· shaft, 101 ··· first shaft through-hole, 102 ··· second shaft through-hole, 11 ··· shaft cylindrical portion, 111 ··· inlet, 12 ··· hollow portion, 13 ··· shaft wall portion, 14 ··· shaft recess, 15 ··· second columnar portion, 2 ··· motor portion, 21 ··· rotor, 211 ··· rotor core, 2111 ··· rotor through-hole, 212 ··· magnet, 22 ··· stator, 221 ··· stator core, 222 ··· coil portion, 2221 ··· coil end, 3 ··· gear portion, 31 ··· reduction gear, 311 ··· main drive gear, 312 ··· intermediate driven gear, 313 ··· final drive gear, 314 ··· intermediate shaft, 32 ··· differential gear, 321 ··· ring gear, 4 ··· housing, 401 ··· motor housing space, 402 ··· gear portion housing space, 403 ··· space, 41 ··· first housing cylindrical portion, 42 ··· side plate portion, 4201 ··· side plate through-hole, 4202 ··· first drive shaft through-hole, 421 ··· first motor bearing holder, 4211 ··· first motor bearing, 422 ··· second motor bearing holder, 4221 ··· second motor bearing, 423 ··· first intermediate bearing holder, 4231 ··· first intermediate bearing, 424 ··· first output bearing holder, 4241 ··· first output bearing, 43 ··· housing cover portion, 431 ··· third motor bearing holder, 4311 ··· third motor bearing, 4312 ··· opening, 432 ··· detector holder, 443 ··· conduction bearing holder, 4331 ··· conduction bearing, 4332 ··· lubricant, 44 ··· cover member, 441 ··· plate portion, 442 ··· first columnar portion, 443 ··· conduction bearing holder, 4431 ··· conduction bearing, 4432 ··· lubricant, 45 ··· second housing cylindrical portion, 46 ··· gear cover portion, 460 ··· second drive shaft through-hole, 461 ··· fourth motor bearing holder, 4611 ··· fourth motor bearing, 462 ··· second intermediate bearing holder, 4621 ··· second intermediate bearing, 463 ··· second output bearing holder, 4631 ··· second output bearing, 464 ··· tray portion, 465 ··· flow path, 5 ··· liquid circulation portion, 51 ··· piping portion, 52 ··· pump53 ··· cooler unit, 54 ··· fluid reservoir, 6 ··· conductive bearing, 61 ··· lubricant, 7 ··· rotation detector, 81 ··· first seal member, 82 ··· second seal member, F ··· fluid, P ··· liquid storage section, Ds, Ds1, Ds2 ··· drive shaft, J1 ··· rotating shaft, J2 ··· intermediate shaft, J3 ··· drive shaft

Claims

1. A shaft extending axially along a rotation axis, a rotor fixed to the shaft and rotatable about the rotation axis, a stator facing the rotor with a radial gap therebetween, a first bearing that rotatably supports the shaft and is lubricated by a fluid, a housing having a first bearing holder that holds the first bearing and houses the rotor and the stator, a second bearing disposed between the shaft and the housing to rotatably support the shaft and lubricated by a lubricant having higher electrical conductivity than the fluid, comprising: the second bearing is disposed in a space isolated from the first bearing holder, the shaft has: a shaft cylindrical portion surrounding the rotation axis, a shaft through hole penetrating the shaft cylindrical portion in a radial direction or a direction intersecting both the radial direction and the axial direction, a shaft wall portion disposed inside the shaft cylindrical portion and extending radially, and having: the fluid can flow inside the shaft cylindrical portion and is supplied to the first bearing through the shaft through hole, a radially outer end portion of the shaft wall portion is connected to an inner peripheral surface of the shaft cylindrical portion, the second bearing is disposed axially on one side of the shaft wall portion inside the shaft cylindrical portion, the shaft through hole is disposed axially on the other side of the shaft wall portion, a drive device.

2. the housing has a first columnar portion extending axially along the rotation axis, the shaft has a shaft recess recessed axially from one axial end of the shaft toward the other axial end, the shaft recess houses at least the other axial side of the first columnar portion, the second bearing fits into the shaft recess, a radially inner end portion of the second bearing contacts a radially outer surface of the first columnar portion, the drive device according to claim 1.

3. the shaft further has a first seal member disposed axially on one side of the second bearing inside the shaft cylindrical portion, the first seal member is fixed to one of an inner peripheral surface of the shaft cylindrical portion and a radially outer surface of the first columnar portion and extends radially from the one toward the other, the drive device according to claim 2.

4. A shaft extending axially along a rotation axis, a rotor fixed to the shaft and rotatable about the rotation axis, a stator facing the rotor with a radial gap therebetween, a first bearing that rotatably supports the shaft and is lubricated by a fluid; a housing that has a first bearing holder for holding the first bearing and houses the rotor and the stator; a second bearing that is disposed between the shaft and the housing, rotatably supports the shaft, and is lubricated by a lubricant having higher electrical conductivity than the fluid; comprising; the second bearing is disposed in a space isolated from the first bearing holder; the housing; a housing cylinder portion that extends in the axial direction and surrounds the rotation shaft; a housing lid portion that has an opening through which the shaft is inserted and is disposed at one axial end portion of the housing cylinder portion; a cover member that is disposed at one axial end portion of the housing lid portion and covers the opening; having; the shaft; a shaft cylinder portion that surrounds the rotation shaft and is rotatably supported by the first bearing; a shaft wall portion that is disposed on one axial side of the shaft cylinder portion and extends radially; a second columnar portion that extends axially in one direction from the shaft wall portion; having; the cover member has a second bearing holder for holding the second bearing; the second bearing rotatably supports the second columnar portion; at least the other axial side of the second bearing holder is housed inside the shaft cylinder portion, a drive device.

5. A shaft that extends axially along a rotation shaft; a rotor that is fixed to the shaft and is rotatable about the rotation shaft; a stator that faces the rotor with a gap in the radial direction; a first bearing that rotatably supports the shaft and is lubricated by a fluid; a housing that has a first bearing holder for holding the first bearing and houses the rotor and the stator; a second bearing that is disposed between the shaft and the housing, rotatably supports the shaft, and is lubricated by a lubricant having higher electrical conductivity than the fluid; a second seal member that is disposed radially outward of the shaft; comprising; the second bearing is disposed in a space isolated from the first bearing holder; the second bearing is disposed on the radially outer surface of the shaft together with the first bearing; the housing further has a second bearing holder for holding the second bearing; The second seal member is disposed between the first bearing and the second bearing in the axial direction, and partitions the first bearing holder and the second bearing holder, in a driving device.

6. The driving device according to any one of claims 1 to 5, wherein the second bearing is disposed coaxially with the first bearing.

7. The driving device according to any one of claims 1 to 6, further comprising a second seal member disposed radially outward of the shaft and between the first bearing and one axial end portion of the shaft in the axial direction.

8. A vehicle having the driving device according to any one of claims 1 to 7.

Images