Drive unit

Abstract

To provide a driving device with a terminal block chamber between an electric motor chamber and a gear chamber to improve insulation properties of the terminal block.SOLUTION: A driving device mounted on a vehicle comprises: a case with an electric motor chamber, a terminal block chamber, and a gear chamber; an electric motor; a terminal block; a reduction gear arranged in the gear chamber; and a hypoid gear arranged in the gear chamber. A first through hole is arranged at a partition wall between the electric motor chamber and the terminal block chamber. A second through hole is arranged at a partition wall between the terminal block chamber and the gear chamber. A rotor shaft of the electric motor extends from the electric motor chamber through the first through hole, the terminal block chamber, and the second through hole to the gear chamber. A gap between the rotor shaft and the second through hole is sealed with oil seal. A first lubrication oil is stored in the electric motor chamber and the terminal block chamber. A second lubrication oil is stored in the gear chamber.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a drive device.

[0002] Patent Document 1 discloses a drive unit that drives the wheels of a vehicle. This drive unit has an electric motor housed in an electric motor chamber and gears housed in a gear chamber. The gears in the gear chamber include a reducer and a hypoid gear. The gear chamber is located next to the electric motor chamber. The driving force of the electric motor is transmitted to a drive shaft via the gear, causing the wheels to rotate. This drive unit also has a terminal block that supplies power to the electric motor. The terminal block chamber that houses the terminal block is located on the opposite side of the electric motor chamber from the gear chamber. In other words, the electric motor chamber is located between the terminal block chamber and the gear chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-050886 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to shorten the overall length of the drive device, a terminal block chamber can be provided between the motor chamber and the gear chamber. This specification proposes a technology for improving the insulation of the terminal block in a drive device in which a terminal block chamber is provided between the motor chamber and the gear chamber. [Means for solving the problem]

[0005] The drive unit disclosed in this specification is mounted on a vehicle. The drive unit has a case, an electric motor, a terminal block, a reducer, and a hypoid gear. The case has a motor chamber, a terminal block chamber, and a gear chamber. The electric motor is housed in the motor chamber. The terminal block is housed in the terminal block chamber and is electrically connected to the electric motor. The reducer is disposed in the gear chamber. The hypoid gear is disposed in the gear chamber. A first through hole is provided in a partition wall between the electric motor chamber and the terminal block chamber. A second through hole is provided in a partition wall between the terminal block chamber and the gear chamber. The electric motor has a rotor shaft that extends from the electric motor chamber through the first through hole, the terminal block chamber, and the second through hole to the gear chamber. Rotation of the rotor shaft is transmitted to the wheels of the vehicle via the reducer and the hypoid gear. A gap between the rotor shaft and the second through hole is sealed by an oil seal. A first lubricating oil is contained in the motor chamber and the terminal block chamber, and a second lubricating oil is contained in the gear chamber.

[0006] The reducer and hypoid gear may be arranged in any order. For example, the rotation of the rotor shaft may be transmitted to the reducer, hypoid gear, and wheels in that order, or the rotation of the rotor shaft may be transmitted to the hypoid gear, reducer, and wheels in that order.

[0007] In this drive device, the terminal block chamber and the gear chamber are separated by an oil seal. Therefore, the gear chamber can contain a different lubricant from the one used in the motor chamber and the terminal block chamber. This allows the gear chamber to use a second lubricant suitable for lubricating the gears, and the motor chamber to use a first lubricant suitable for lubricating the motor. Furthermore, since the terminal block chamber also contains the first lubricant, an oil film of the first lubricant forms on the surface of the terminal block. This improves the insulation of the terminal block and allows for a more compact terminal block. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a drive device according to a first embodiment taken along the left-right direction. [Figure 2] FIG. 2 is a cross-sectional view of the left drive system 90 along the left-right direction. [Figure 3] FIG. 2 is a cross-sectional view of the left drive system 90 along the vertical direction. [Figure 4] FIG. 2 is an enlarged cross-sectional view of an oil seal 25. [Figure 5] FIG. 10 is a cross-sectional view of a drive device according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a drive device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following are additional features of the drive device disclosed in this specification:

[0010] The first lubricating oil may circulate between the motor chamber and the terminal block chamber during operation of the motor.

[0011] According to this configuration, the electric motor can be effectively cooled by the first lubricating oil.

[0012] The viscosity of the first lubricant may be lower than the viscosity of the second lubricant.

[0013] According to this configuration, the high viscosity of the second lubricating oil prevents oil film breakdown on the gear tooth surface. Furthermore, the low viscosity of the first lubricating oil allows the rotor of the electric motor to rotate with low loss. Furthermore, the low viscosity of the first lubricating oil makes it easier for an oil film of the first lubricating oil to form on the surface of the terminal block, effectively improving the insulation of the terminal block.

[0014] The oil seal may have a first seal portion that contacts the outer peripheral surface of the rotor shaft and the inner peripheral surface of the second through hole, and a second seal portion that contacts the outer peripheral surface of the rotor shaft and the inner peripheral surface of the second through hole at a position closer to the gear chamber than the first seal portion.

[0015] This configuration effectively prevents leakage of lubricating oil from the oil seal.

[0016] The case may be provided with an oil discharge passage that opens onto the inner circumferential surface of the second through hole at a position between the first seal portion and the second seal portion.

[0017] This configuration makes it possible to more effectively prevent leakage of lubricating oil from the oil seal. [Example]

[0018] A drive unit 10 of the first embodiment shown in FIG. 1 is mounted on an electric vehicle. In FIG. 1, an arrow FR indicates the front direction of the vehicle, and an arrow RH indicates the right direction of the vehicle. The drive unit 10 has a case 12. A left drive train 90 and a right drive train 91 are provided inside the case 12. The left drive train 90 drives a left rear wheel 92 of the electric vehicle. The right drive train 91 drives a right rear wheel 93 of the electric vehicle. The left drive train 90 and the right drive train 91 are bilaterally symmetrical, so the left drive train 90 will be described below.

[0019] The case 12 is provided with a left motor chamber 13, a left terminal block chamber 14, a left counter gear chamber 15, and a left hypoid gear chamber 16 inside. The left terminal block chamber 14 is located rearward of the left motor chamber 13. The left counter gear chamber 15 is located rearward of the left terminal block chamber 14. The left hypoid gear chamber 16 is located rearward of the left counter gear chamber 15. The left motor chamber 13 houses an electric motor 20. The left terminal block chamber 14 houses a terminal block 20e. The terminal block 20e is equipped with terminals for supplying power to the electric motor 20. The left counter gear chamber 15 houses a gear set constituting a counter gear. The left hypoid gear chamber 16 houses a gear set constituting a hypoid gear. A left drive system 90 is formed by the electric motor 20, the gear set in the left counter gear chamber 15, and the gear set in the left hypoid gear chamber 16, etc.

[0020] As shown in FIG. 2, the electric motor 20 has a rotor 20a and a stator 20b. The rotor 20a has a rotor shaft 20c. The rotor shaft 20c has shafts 20c-1 and 20c-2. Shaft 20c-1 has a cylindrical shape. Shaft 20c-2 has a columnar shape. One end of shaft 20c-2 is inserted into shaft 20c-1. Shaft 20c-2 is fixed to shaft 20c-1 by a spline engagement. The rotor 20a is housed in the left motor chamber 13 with the rotor shaft 20c extending along the fore-and-aft direction of the electric vehicle. A through-hole 18 is provided in the partition wall between the left motor chamber 13 and the left terminal block chamber 14. A through-hole 19 is provided in the partition wall between the left terminal block chamber 14 and the left counter gear chamber 15. The rotor shaft 20c extends from the left motor chamber 13 to the left counter gear chamber 15 through the through-hole 18, the left terminal block chamber 14, and the through-hole 19. More specifically, the shaft 20c-1 extends from the left motor chamber 13 to the left terminal block chamber 14, and the shaft 20c-2 extends from the left terminal block chamber 14 to the left counter gear chamber 15. The rotor 20a is rotatably supported by bearings provided in the case 12. The gap between the outer circumferential surface of the shaft 20c-2 and the inner circumferential surface of the through-hole 19 is sealed by an oil seal 25. The stator 20b is disposed around the rotor 20a. The stator 20b is electrically connected to the terminal block 20e. When current is supplied to the stator 20b via the terminal block 20e, the rotor 20a rotates.

[0021] An output shaft 24 is disposed within the left counter gear chamber 15. The output shaft 24 is disposed parallel to the rotor shaft 20c. More specifically, the central axis of the output shaft 24 is parallel to the central axis of the rotor shaft 20c. The output shaft 24 is rotatably supported by a bearing provided in the case 12. The output shaft 24 penetrates a partition wall between the left counter gear chamber 15 and the left hypoid gear chamber 16 and extends from the left counter gear chamber 15 to the left hypoid gear chamber 16. The output shaft 24 is rotatably supported by a bearing provided in the case 12.

[0022] The gear set provided in the left counter gear chamber 15 has gears 22a and 22b. Gear 22a is a cylindrical gear and is fixed to the rotor shaft 20c. Gear 22b is a cylindrical gear and is fixed to the output shaft 24. Gear 22a is engaged with gear 22b. Gear 22a and gear 22b form a counter gear 22.

[0023] When the rotor shaft 20c rotates, the gear 22a rotates. When the gear 22a rotates, a driving force is transmitted from the gear 22a to the gear 22b. As a result, the gear 22b and the output shaft 24 rotate. The gear ratio of the counter gear 22 is set so that the rotation speed of the output shaft 24 is slower than the rotation speed of the rotor shaft 20c. In this way, the drive system in the left counter gear chamber 15 forms a reducer.

[0024] A drive shaft 27 is disposed within the left hypoid gear chamber 16. The drive shaft 27 extends in the left-right direction of the electric vehicle. The drive shaft 27 extends from the left hypoid gear chamber 16 through the left wall of the case 12 to the outside of the case 12. As shown in FIG. 1 , a left rear wheel 92 is connected to the left end of the drive shaft 27. The drive shaft 27 is rotatably supported by a bearing provided in the case 12.

[0025] As shown in Fig. 2, the gear set provided in the left hypoid gear chamber 16 has gears 28a and 28b. Gear 28a is a truncated cone gear and is fixed to the output shaft 24. Gear 28b is a truncated cone gear and is fixed to the drive shaft 27. Gear 28a is engaged with gear 28b. Gears 28a and 28b form the hypoid gear 28.

[0026] When the electric motor 20 is driven, the rotor shaft 20c rotates. As described above, when the rotor shaft 20c rotates, the output shaft 24 rotates. When the output shaft 24 rotates, the gear 28a rotates, and driving force is transmitted from the gear 28a to the gear 28b. As a result, the gear 28b and the drive shaft 27 rotate. When the drive shaft 27 rotates, the left rear wheel 92 rotates. In this way, the left drivetrain 90 rotates the left rear wheel 92 by the driving force of the electric motor 20.

[0027] As shown in FIG. 2, the drive unit 10 has an oil reservoir 46. The oil reservoir 46 may be provided inside the case 12 or outside the case 12. A first lubricating oil 80 is stored in the oil reservoir 46. As will be described in detail later, the first lubricating oil 80 circulates through the left motor chamber 13 and the left terminal block chamber 14. As shown in FIG. 3, a second lubricating oil 82 is stored in the bottom of the left counter gear chamber 15 and the left hypoid gear chamber 16. The first lubricating oil 80 is a different type of lubricating oil from the second lubricating oil 82. The viscosity of the first lubricating oil 80 is lower than the viscosity of the second lubricating oil 82. The left counter gear chamber 15 and the left hypoid gear chamber 16 are connected at a position not shown. Therefore, the second lubricating oil 82 can flow between the left counter gear chamber 15 and the left hypoid gear chamber 16. The left terminal block chamber 14 and the left counter gear chamber 15 are separated by a partition wall, except for the through-hole 19. The through-hole 19 is sealed by an oil seal 25. The oil seal 25 prevents lubricating oil from leaking between the left terminal block chamber 14 and the left counter gear chamber 15. In this way, the left terminal block chamber 14 and the left counter gear chamber 15 are separated so that the lubricating oils do not mix.

[0028] The lower part of gear 28b is immersed in second lubricating oil 82. Therefore, when gear 28b rotates, second lubricating oil 82 is dispersed into left counter gear chamber 15 and left hypoid gear chamber 16. As a result, gears 22a, 22b and gears 28a, 28b are lubricated by second lubricating oil 82. High pressure is applied to the tooth surfaces of each gear. In this embodiment, the high viscosity of second lubricating oil 82 prevents oil film breakdown on the tooth surfaces of gears 22a, 22b and gears 28a, 28b.

[0029] As shown in FIG. 2, the drive unit 10 has an oil discharge passage 35 and an oil supply passage 36. An oil discharge port 34 is formed at the bottom of the left terminal block chamber 14. The upstream end of the oil discharge passage 35 is connected to the oil discharge port 34. The downstream end of the oil discharge passage 35 is connected to the oil reservoir tank 46. The upstream end of the oil supply passage 36 is connected to the oil reservoir tank 46. As described above, the shaft 20c-1 has a cylindrical shape. The shaft passage 38 is formed by the central hole of the shaft 20c-1. The downstream end of the oil supply passage 36 is connected to the front end of the shaft passage 38. The oil supply passage 36 is provided with an oil pump 30. The oil pump 30 pumps the first lubricating oil 80 from the oil reservoir tank 46 toward the shaft passage 38. The shaft 20c-1 is provided with a plurality of oil discharge ports 40 extending from the shaft passage 38 to the outer circumferential surface of the shaft 20c-1. The case 12 is provided with an oil flow path 48 that connects the left motor chamber 13 and the left terminal block chamber 14 .

[0030] While the electric motor 20 is operating, the oil pump 30 operates. When the oil pump 30 operates, the first lubricating oil 80 stored in the oil reservoir 46 is supplied to the shaft flow path 38 in the shaft 20c-1 via the oil supply flow path 36. The first lubricating oil flows rearward through the shaft flow path 38. The electric motor 20 is cooled by the first lubricating oil flowing through the shaft flow path 38. The first lubricating oil in the shaft flow path 38 is discharged from the oil discharge port 40 into the left electric motor chamber 13. The electric motor 20 is lubricated by the first lubricating oil discharged into the left electric motor chamber 13. The first lubricating oil discharged into the left electric motor chamber 13 flows through the oil flow path 48 to the left terminal block chamber 14. The terminal block 20e is cooled by the first lubricating oil. The first lubricating oil in the left terminal block chamber 14 flows through the oil discharge port 34 and the oil discharge flow path 35 to the oil reservoir 46. As described above, when the oil pump 30 operates, the first lubricating oil circulates between the left motor chamber 13 and the left terminal block chamber 14. As the first lubricating oil circulates, it is applied to the surface of the terminal block 20e. As a result, an oil film of the first lubricating oil is formed on the surface of the terminal block 20e. Because the surface of the terminal block 20e is covered with an oil film of the first lubricating oil, the insulating properties of the terminal block 20e are improved. In particular, because the viscosity of the first lubricating oil is low, an oil film of the first lubricating oil is easily formed on the surface of the terminal block 20e. Therefore, high insulating properties can be achieved in the terminal block 20e. This makes it possible to shorten the insulating distance between each terminal of the terminal block 20e and the case 12. This allows the drive device 10 to be made more compact.

[0031] As described above, in the drive device 10 of the first embodiment, the left terminal block chamber 14 and the left counter gear chamber 15 are separated by the oil seal 25, and different lubricating oils are used in each separated chamber. The use of the second lubricating oil with high viscosity in the left counter gear chamber 15 and the left hypoid gear chamber 16 prevents oil film breakdown on the tooth surfaces of each gear. The use of the first lubricating oil with low viscosity in the left electric motor chamber 13 and the left terminal block chamber 14 allows the oil pump 30 to efficiently circulate the first lubricating oil, thereby efficiently cooling the electric motor 20 and the terminal block 20e. The use of the first lubricating oil with low viscosity in the left electric motor chamber 13 allows the rotor 20a to rotate with low loss. The use of the same first lubricating oil (i.e., low-viscosity lubricating oil) in the left terminal block chamber 14 as in the left electric motor chamber 13 effectively improves the insulation of the terminal block 20e.

[0032] FIG. 4 shows a cross section of the oil seal 25 and its surrounding area. As shown in FIG. 4, the oil seal 25 has a double-lip structure that seals the oil at two locations: seal portions 25a and 25b. The seal portion 25a contacts the outer peripheral surface of the rotor shaft 20c and the inner peripheral surface of the through-hole 19. The seal portion 25b is spaced from the seal portion 25a and is located close to the left counter gear chamber 15. The seal portion 25b contacts the outer peripheral surface of the rotor shaft 20c and the inner peripheral surface of the through-hole 19. The case 12 also has an oil discharge passage 50 that opens to the inner peripheral surface of the through-hole 19 in the gap 25c between the seal portions 25a and 25b. An oil reservoir 52 is provided at the other end of the oil discharge passage 50. The oil reservoir 52 has a discharge port 54 that leads to the outside of the case 12. The discharge port 54 is closed by a cap 56. The first lubricating oil may leak from the left terminal block chamber 14, passing over the seal portion 25a, into the gap 25c. The second lubricating oil may leak from the left counter gear chamber 15, passing over the seal portion 25b, into the gap 25c. The lubricating oil that leaks into the gap 25c in this manner is discharged from the oil drain path 50 to the oil reservoir 52. The lubricating oil that accumulates in the oil reservoir 52 is discharged to the outside of the case 12 through the drain port 54 during maintenance. This configuration makes it possible to prevent the first lubricating oil from leaking from the left terminal block chamber 14 to the left counter gear chamber 15, and the second lubricating oil from leaking from the left counter gear chamber 15 to the left terminal block chamber 14.

[0033] The gear configuration may be different from that of Example 1. For example, the gear may be configured as in Examples 2 and 3 described below.

[0034] FIG. 5 shows a drive unit of a second embodiment. In the second embodiment, a counter shaft 100 and a counter gear 110 are housed in the left counter gear chamber 15. The counter gear 110 transmits the rotation of the rotor shaft 20c to the counter shaft 100. In the second embodiment, the output shaft 24 is arranged coaxially with the rotor shaft 20c. The counter gear 22 transmits the rotation of the counter shaft 100 to the output shaft 24. Other configurations of the second embodiment are the same as those of the first embodiment. As in the second embodiment, the drive unit may have multiple counter gears.

[0035] FIG. 6 shows a drive unit of a third embodiment. In the third embodiment, an intermediate shaft 130 is disposed in the gear chamber. The intermediate shaft 130 extends in the left-right direction of the vehicle. The hypoid gear 28 is disposed between the rotor shaft 20c and the intermediate shaft 130. The hypoid gear 28 transmits the rotation of the rotor shaft 20c to the intermediate shaft 130. The counter gear 22 is disposed between the intermediate shaft 130 and the drive shaft 27. The counter gear 22 transmits the rotation of the intermediate shaft 130 to the drive shaft 27. The other configurations of the third embodiment are the same as those of the first embodiment. As in the third embodiment, a counter gear may be disposed downstream of the hypoid gear.

[0036] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0037] 10: Drive unit 12: Case 13:Left motor room 14:Left terminal block room 15: Left counter gear room 16: Left hypoid gear chamber 18:Through hole 19:Through hole 20: Electric motor 20c: rotor shaft 20e:Terminal block 22: Counter gear 27: Drive shaft 28: Hypoid gear 80:1st lubricant 82:Second lubricant

Claims

1. A drive device mounted on a vehicle, a case having a motor chamber, a terminal block chamber, and a gear chamber; an electric motor housed in the electric motor chamber; a terminal block housed in the terminal block chamber and electrically connected to the electric motor; a reducer disposed in the gear chamber; a hypoid gear disposed in the gear chamber; and a first through hole is provided in a partition wall between the motor chamber and the terminal block chamber, a second through-hole is provided in a partition wall between the terminal block chamber and the gear chamber, the electric motor has a rotor shaft that extends from the electric motor chamber through the first through hole, the terminal block chamber, and the second through hole to the gear chamber, The rotation of the rotor shaft is transmitted to the wheels of the vehicle via the reducer and the hypoid gear, a gap between the rotor shaft and the second through hole is sealed by an oil seal; a first lubricating oil is accommodated in the motor chamber and the terminal block chamber; A second lubricating oil is contained in the gear chamber. Drive unit.

2. The drive device according to claim 1 , wherein the first lubricating oil circulates between the motor chamber and the terminal block chamber during operation of the electric motor.

3. The drive device according to claim 1 or 2, wherein the viscosity of the first lubricating oil is lower than the viscosity of the second lubricating oil.

4. 3. The drive device according to claim 1, wherein the oil seal has a first seal portion that contacts the outer peripheral surface of the rotor shaft and the inner peripheral surface of the second through hole, and a second seal portion that contacts the outer peripheral surface of the rotor shaft and the inner peripheral surface of the second through hole at a position closer to the gear chamber than the first seal portion.

5. The drive device according to claim 4 , wherein the case is provided with an oil discharge passage that opens onto the inner circumferential surface of the second through hole at a position between the first seal portion and the second seal portion.

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