Drive device

Abstract

A drive device mounted on a vehicle includes: an electric motor housed in an electric motor chamber; a first shaft disposed parallel to or coaxial with a rotor shaft of the motor; a counter gear for transmitting the rotation of the rotor shaft to the first shaft; a second shaft that rotates a wheel of the vehicle; a hypoid gear that transmits the rotation of the first shaft to the second shaft; an oil seal for sealing a gap between the first shaft and the housing; a first lubricating oil stored in the motor chamber and the counter gear chamber; and a second lubricating oil stored in the hypoid gear chamber.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a driving device. Background Art

[0002] The drive device disclosed in Japanese Patent Laid-Open No. 2004-050886 has an electric motor, a pinion shaft, a wheel shaft, a counter gear (Japanese: ウンタギヤ) and a hypoid gear (Japanese: ハイポイドギヤ). The pinion shaft is arranged in parallel with the rotor shaft of the electric motor. The counter gear transmits the rotation of the rotor shaft to the pinion shaft. The wheel shaft extends in a direction different from the rotor shaft. The hypoid gear transmits the rotation of the pinion shaft to the wheel shaft. The electric motor is housed in a motor chamber. The counter gear and the hypoid gear are housed in a common gear chamber. Lubricating oil is stored in the gear chamber. The gear chamber and the motor chamber are isolated by a sealing material or the like. Summary of the invention

[0003] The type of lubricating oil suitable for the counter gear is different from the type of lubricating oil suitable for the hypoid gear. In Japanese Patent Application Laid-Open No. 2004-050886, since the same lubricating oil is used for the counter gear and the hypoid gear, the performance of one of the counter gear and the hypoid gear cannot be fully and effectively utilized. In this specification, a technology is proposed to make both the counter gear and the hypoid gear operate appropriately.

[0004] The drive device disclosed in this specification is mounted on a vehicle. The drive device includes: a housing having a motor chamber, a counter gear chamber, and a hypoid gear chamber; a motor housed in the motor chamber; a first shaft arranged to be parallel or coaxial with the rotor shaft of the motor and extending from the counter gear chamber to the hypoid gear chamber; a counter gear housed in the counter gear chamber and transmitting the rotation of the rotor shaft to the first shaft; a second shaft extending from the hypoid gear chamber to the outside of the housing and rotating the wheels of the vehicle; a hypoid gear housed in the hypoid gear chamber and transmitting the rotation of the first shaft to the second shaft; an oil seal sealing a gap between the first shaft and the housing; a first lubricating oil stored in the motor chamber and the counter gear chamber; and a second lubricating oil stored in the hypoid gear chamber.

[0005] In this drive device, the reversing gear chamber is isolated from the hypoid gear chamber by an oil seal. Therefore, different lubricating oils can be used in the reversing gear chamber and the hypoid gear chamber. Therefore, both the reversing gear and the hypoid gear can operate efficiently. In addition, a common first lubricating oil is used in the motor chamber and the reversing gear chamber. Even if a common lubricating oil is used in the motor and the reversing gear, they can operate efficiently. In addition, by using a common lubricating oil in the motor chamber and the reversing gear chamber, the increase in the types of lubricating oils used in the drive device can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like parts, and in which:

[0007] Figure 1 is a cross-sectional view of the drive device along the left-right direction;

[0008] Figure 2 is a cross-sectional view of the left drive system 90 along the left-right direction;

[0009] Figure 3 It is a cross-sectional view of the left drive system 90 along the front-rear direction. DETAILED DESCRIPTION

[0010] The following lists additional features of the drive device disclosed in this specification.

[0011] The viscosity of the first lubricating oil may be lower than the viscosity of the second lubricating oil.

[0012] According to this configuration, the oil film on the tooth surface of the hypoid gear can be prevented from breaking by the second lubricating oil having high viscosity, and the rotor and the counter gear can be rotated with low loss by the first lubricating oil having low viscosity.

[0013] The drive device may further include an oil pump that circulates the first lubricating oil between the motor chamber and the counter gear chamber.

[0014] According to this configuration, the electric motor and the counter gear can be cooled.

[0015] Figure 1 The driving device 10 of the embodiment shown is mounted on an electric vehicle (electrified vehicle). Figure 1In the figure, arrow FR indicates the front direction of the vehicle, and arrow RH indicates the right direction of the vehicle. The drive device 10 has a housing 12. Inside the housing 12, a left drive system 90 and a right drive system 91 are provided. The left drive system 90 drives the left rear wheel 92 of the electric vehicle. The right drive system 91 drives the right rear wheel 93 of the electric vehicle. Since the left drive system 90 and the right drive system 91 are symmetrical, the left drive system 90 will be described below.

[0016] Inside the housing 12, there are provided a left motor chamber 13, a left terminal plate chamber 14, a left reversing gear chamber 15, and a left hypoid gear chamber 16. The left terminal plate chamber 14 is arranged at the rear of the left motor chamber 13. The left reversing gear chamber 15 is arranged at the rear of the left terminal plate chamber 14. The left hypoid gear chamber 16 is arranged at the rear of the left reversing gear chamber 15. The motor 20 is accommodated in the left motor chamber 13. The terminal plate 20e is accommodated in the left terminal plate chamber 14. The terminal plate 20e has terminals for supplying power to the motor 20. The gear set constituting the reversing gear is accommodated in the left reversing gear chamber 15. The gear set constituting the hypoid gear is accommodated in the left hypoid gear chamber 16. The left drive system 90 is constituted by the motor 20, the gear set in the left reversing gear chamber 15, and the gear set in the left hypoid gear chamber 16.

[0017] like Figure 2 As shown, 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 a shaft 20c-1 and a shaft 20c-2. The shaft 20c-1 and the shaft 20c-2 each have a cylindrical shape. One end of the shaft 20c-1 is inserted into the shaft 20c-2. The shaft 20c-1 is fixed to the shaft 20c-2 by spline fitting. The rotor 20a is housed in the left motor chamber 13 in the direction in which the rotor shaft 20c extends in the front-rear direction of the electric vehicle. The rotor shaft 20c extends from the left motor chamber 13 to the left counter gear chamber 15 through the partition wall of the housing 12. More specifically, the shaft 20c-1 extends from the left motor chamber 13 to the left terminal plate chamber 14, and the shaft 20c-2 extends from the left terminal plate chamber 14 to the left counter gear chamber 15. The rotor 20a is rotatably supported by a bearing provided in the housing 12. The stator 20b is arranged around the rotor 20a. The stator 20b is electrically connected to the terminal plate 20e. When current is supplied to the stator 20b through the right terminal plate 20e, the rotor 20a rotates.

[0018] In the left counter gear chamber 15, a counter shaft 23 and an output shaft 24 are arranged. The counter shaft 23 is arranged in parallel with the rotor shaft 20c. More specifically, the center axis of the counter shaft 23 is parallel to the center axis of the rotor shaft 20c. The counter shaft 23 is rotatably supported by a bearing provided in the housing 12. The output shaft 24 is arranged behind the rotor shaft 20c. The output shaft 24 extends coaxially with the rotor shaft 20c. More specifically, the center axis of the output shaft 24 coincides with the extension line of the center axis of the rotor shaft 20c. A through hole 18 is provided in the partition wall between the left counter gear chamber 15 and the left hypoid gear chamber 16. The output shaft 24 extends from the left counter gear chamber 15 to the left hypoid gear chamber 16 through the through hole 18. The gap between the outer peripheral surface of the output shaft 24 and the inner peripheral surface of the through hole 18 is sealed by an oil seal 25. The front end of the output shaft 24 is inserted into the center hole of the rotor shaft 20c from the rear end thereof. The gap between the inner circumference of the rotor shaft 20c and the outer circumference of the output shaft 24 is sealed by an oil seal 26. The output shaft 24 is rotatably supported by a bearing provided in the housing 12.

[0019] The gear set provided in the left counter gear chamber 15 includes gears 21a, 21b, 22a, and 22b. Gear 21a is a cylindrical gear fixed to the rotor shaft 20c. Gear 21b is a cylindrical gear fixed to the counter shaft 23. Gear 21a engages with gear 21b. Gear 21a and gear 21b constitute the first counter gear 21. Gear 22a is a cylindrical gear fixed to the counter shaft 23. Gear 22b is a cylindrical gear fixed to the output shaft 24. Gear 22a engages with gear 22b. Gear 22a and gear 22b constitute the second counter gear 22.

[0020] If the rotor shaft 20c rotates, the gear 21a rotates, and the driving force is transmitted from the gear 21a to the gear 21b. Therefore, the gear 21b, the countershaft 23 and the gear 22a rotate. If the gear 22a rotates, the driving force is transmitted from the gear 22a to the gear 22b. Therefore, the gear 22b and the output shaft 24 rotate. The gear ratio of the first counter gear 21 is set so that the rotation speed of the countershaft 23 is slower than the rotation speed of the rotor shaft 20c. In addition, the gear ratio of the second counter gear 22 is set so that the rotation speed of the output shaft 24 is slower than the rotation speed of the countershaft 23. Therefore, the output shaft 24 rotates at a lower speed than the rotor shaft 20c. In this way, the drive system in the left counter gear chamber 15 constitutes a speed reducer.

[0021] A drive shaft 27 is disposed in 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 side wall of the housing 12 to the outside of the housing 12. Figure 1As shown, the 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 housing 12.

[0022] like Figure 2 As shown, the gear set provided in the left hypoid gear chamber 16 includes gears 28a and 28b. Gear 28a is a truncated cone gear fixed to the output shaft 24. Gear 28b is a truncated cone gear fixed to the drive shaft 27. Gear 28a engages with gear 28b. Gear 28a and gear 28b constitute a hypoid gear 28.

[0023] When the 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 the driving force is transmitted from the gear 28a to the gear 28b. Therefore, 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 drive system 90 rotates the left rear wheel 92 by the driving force of the motor 20.

[0024] like Figure 3 As shown, the first lubricating oil 80 is stored at the bottom of the left counter gear chamber 15. In addition, the second lubricating oil 82 is stored at the bottom of the left hypoid gear chamber 16. The first lubricating oil 80 is a lubricating oil of a different type 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 separated by a partition wall except for the through hole 18. In addition, the through hole 18 is sealed by an oil seal 25. The oil seal 25 can prevent the lubricating oil from leaking between the left counter gear chamber 15 and the left hypoid gear chamber 16. In this way, the left counter gear chamber 15 and the left hypoid gear chamber 16 are separated in a manner that does not allow the lubricating oil to mix.

[0025] The lower part of the gear 28b is immersed in the second lubricating oil 82. Therefore, when the gear 28b rotates, the hypoid gear 28 is lubricated by the second lubricating oil 82. Generally speaking, a higher pressure is easily applied to the tooth surface of the hypoid gear than to the tooth surface of the counter gear (i.e., the bevel gear, the spur gear, etc.). Therefore, the oil film is easily broken on the tooth surface of the hypoid gear. In the present embodiment, the pressure applied to the tooth surface of the hypoid gear 28 is higher than the pressure applied to the tooth surface of the first counter gear 21 and the second counter gear 22. However, in the present embodiment, since the hypoid gear 28 is lubricated by the second lubricating oil 82 with high viscosity, the oil film at the tooth surface of the hypoid gear 28 can be prevented from breaking.

[0026] An oil suction port 34 is provided at the bottom of the left counter gear chamber 15. Figure 2As shown in FIG. 1 , the drive device 10 includes an oil circulation flow path 35. The upstream end of the oil circulation flow path 35 is connected to the oil suction port 34. As described above, the rotor shaft 20c has a cylindrical shape. The axial flow path 36 is formed by the center hole of the rotor shaft 20c. The downstream end of the oil circulation flow path 35 is connected to the front end of the axial flow path 36. The oil pump 30 is provided in the oil circulation flow path 35. The oil pump 30 sends the first lubricating oil 80 in the oil circulation flow path 35 from the oil suction port 34 to the axial flow path 36. The rotor shaft 20c (i.e., the shaft 20c-1) in the left motor chamber 13 is provided with a plurality of oil discharge ports 40 extending from the axial flow path 36 to the outer peripheral surface of the rotor shaft 20c. The rotor shaft 20c (i.e., the shaft 20c-2) in the left counter gear chamber 15 is provided with a plurality of oil discharge ports 42 extending from the axial flow path 36 to the outer peripheral surface of the rotor shaft 20c. An axial flow path 38 extending along the central axis of the output shaft 24 is provided inside the output shaft 24. The front end of the axial flow path 38 is connected to the axial flow path 36. The output shaft 24 is provided with a plurality of oil discharge ports 44 extending from the axial flow path 38 to the outer peripheral surface of the output shaft 24.

[0027] During the operation of the motor 20, the oil pump 30 operates. When the oil pump 30 operates, the first lubricating oil 80 stored in the left counter gear chamber 15 is supplied to the axial flow path 36 in the rotor shaft 20c through the oil suction port 34 and the oil circulation flow path 35. The first lubricating oil flows backward in the axial flow path 36. The motor 20 is cooled by the first lubricating oil flowing in the axial flow path 36. A portion of the first lubricating oil in the axial flow path 36 is discharged from the oil discharge port 40 into the left motor chamber 13. The motor 20 is lubricated by the first lubricating oil discharged into the left motor chamber 13. The first lubricating oil discharged into the left motor chamber 13 flows into the left counter gear chamber 15 through the oil flow path and the left terminal board chamber 14 (not shown). A portion of the first lubricating oil in the axial flow path 36 is discharged from the oil discharge port 42 into the left counter gear chamber 15. The first counter gear 21 is lubricated and cooled by the first lubricating oil discharged from the oil discharge port 42. The first lubricating oil flowing to the rear end in the axial flow path 36 flows into the axial flow path 38 in the output shaft 24. The first lubricating oil in the axial flow path 38 is discharged from the oil discharge port 44 into the left counter gear chamber 15. The second counter gear 22 is lubricated and cooled by the first lubricating oil discharged from the oil discharge port 44.

[0028] As described above, by circulating the first lubricating oil between the left motor chamber 13 and the left reverse gear chamber 15, the motor 20, the first reverse gear 21, and the second reverse gear 22 are cooled and lubricated. Since the pressure applied to the tooth surfaces of the first reverse gear 21 and the second reverse gear 22 is low, even if the viscosity of the first lubricating oil is low, the oil film at the tooth surfaces of the first reverse gear 21 and the second reverse gear 22 can be prevented from rupturing. In addition, since the viscosity of the first lubricating oil is low, the rotor 20a, the first reverse gear 21, and the second reverse gear 22 can rotate with low loss. In addition, since the viscosity of the first lubricating oil is low, the first lubricating oil can be efficiently circulated by the oil pump 30. In this way, by using the first lubricating oil with low viscosity for the motor 20 and the reverse gear, the loss can be suppressed.

[0029] In addition, in the above-mentioned embodiment, the first counter gear 21 and the second counter gear 22 are provided in the left counter gear chamber 15. However, the counter gear provided in the left counter gear chamber 15 may be a set. In this case, the counter shaft can be arranged so as to extend from the left counter gear chamber 15 to the left hypoid gear chamber 16, and each shaft and each gear can be arranged so as to transmit the driving force from the counter shaft to the drive shaft via the hypoid gear.

[0030] In the above-mentioned embodiment, the left counter gear chamber 15 functions as a storage tank for storing the first lubricating oil. However, a storage tank for storing the first lubricating oil may be provided separately from the left counter gear chamber 15. In this case, the left counter gear chamber 15 may not store the first lubricating oil.

[0031] The above detailed description of the implementation methods is provided, but these are merely examples and do not limit the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings can exert technical practicality alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings achieves multiple purposes at the same time, and achieving only one of the purposes itself can have technical practicality.

Claims

1. A driving device, the driving device being mounted on a vehicle, in, The above-mentioned driving device comprises: A housing having a motor chamber, a counter gear chamber, and a hypoid gear chamber; An electric motor, the electric motor being accommodated in the electric motor chamber; a first shaft, the first shaft being arranged parallel to or coaxial with the rotor shaft of the electric motor and extending from the counter gear chamber to the hypoid gear chamber; a reverse gear housed in the reverse gear chamber and transmitting the rotation of the rotor shaft to the first shaft; a second shaft extending from the hypoid gear chamber to the outside of the housing and rotating a wheel of the vehicle; a hypoid gear, the hypoid gear being received in the hypoid gear chamber and transmitting the rotation of the first shaft to the second shaft; an oil seal, the oil seal sealing a gap between the first shaft and the housing; a first lubricating oil stored in the motor chamber and the counter gear chamber; and The second lubricating oil is stored in the hypoid gear chamber.

2. The driving device according to claim 1, in, The viscosity of the first lubricating oil is lower than the viscosity of the second lubricating oil.

3. The drive device according to claim 1 or 2, in, The drive device further includes an oil pump configured to circulate the first lubricating oil between the motor chamber and the counter gear chamber.

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