Electric drive unit

Abstract

An electric drive unit, comprising: an electric motor; an input pinion driven by an output shaft of the electric motor around a first axis; a pair of first gears each meshed with the input pinion and rotatable around a respective second axis; a second gear meshed with the first gear and rotatable around a third axis; a third gear driven by the second gear around the third axis; a fourth gear meshed with the third gear and rotatable around a fourth axis; and a differential device, wherein the differential device has a differential input part rotatably coupled to the third gear, and a pair of differential output parts driven by the differential input part and rotatable around the fourth axis. The first, second, third and fourth axes are parallel to each other. The third axis is offset from the first and second axes.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 357,058, filed Jun. 30, 2022, the disclosure of which is incorporated herein by reference as if fully and specifically set forth herein.

[0002]

[0002] This disclosure relates to an electric drive unit.

Background Art

[0003]

[0003] This section provides background information related to the present disclosure, which is not necessarily prior art.

[0004]

[0004] U.S. Patent No. 11,293,534 discloses an electric drive module having a relatively compact transmission configured to provide a relatively high overall reduction ratio between the output shaft of an electric motor and the output of the transmission. Such a transmission is suitable for its intended purpose, nevertheless, there is a need for a technology for a relatively compact transmission that achieves a relatively high overall reduction ratio.

Summary of the Invention

[0005]

[0005] This section provides a general overview of the present disclosure and is not an exhaustive disclosure of its full scope or all of its features.

[0006]

[0006] In one form, the present disclosure provides an electric drive unit including an electric motor, an input pinion, a pair of first reduction gears, a second reduction gear, a third reduction gear, a fourth reduction gear, and a differential assembly. The electric motor has a motor output shaft rotatable about a first axis of rotation. The input pinion is driven by the motor output shaft about the first axis of rotation. Each of the first reduction gears is meshed with the input pinion and is rotatable about a respective second axis of rotation parallel to the first axis of rotation. The second reduction gear is meshed with the first reduction gears and is rotatable about a third axis of rotation parallel to the first and second axes of rotation and offset from the first and second axes of rotation. The third reduction gear is driven by the second reduction gear about the third axis of rotation. The fourth reduction gear is meshed with the third reduction gear and is rotatable about a fourth axis of rotation parallel to the second and third axes of rotation. The differential assembly has a differential input and a pair of differential outputs. The differential input is coupled to the third reduction gear to rotate therewith about the fourth axis of rotation. Each of the differential outputs is driven by the differential input and is rotatable about the fourth axis of rotation.

[0007]

[0007] Further applicable fields will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0008]

[0008] The drawings described herein are for the purpose of illustration of selected embodiments only and are not intended to limit the scope of the present disclosure, not being all possible implementations.

Brief Description of the Drawings

[0009]

Figure 1

[0009] Partial cross-sectional perspective view of an exemplary electric drive unit constructed in accordance with the teachings of the present disclosure.

Figure 2

[0010] Perspective view of the transmission of the electric drive unit of FIG. 1.

Figure 3

[0011] Partial cross-sectional elevation view of a second exemplary electric drive unit constructed in accordance with the teachings of the present disclosure.

Figure 4

[0012] Perspective view of the transmission of the electric drive unit of FIG. 3.

Figure 5

[0013] Perspective view of a portion of a third electric drive unit constructed in accordance with the teachings of the present disclosure.

Figure 6

[0014] Longitudinal cross-sectional view of a portion of the electric drive unit of FIG. 5 showing the sun gear of the planetary reducer in the first position.

Figure 7

[0015] Cross-sectional view taken along line 7-7 of FIG. 5.

Figure 8

[0016] A view similar to FIG. 6 but showing the sun gear of the planetary reducer in the second position.

DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0017] Corresponding reference numerals indicate corresponding parts throughout several views of the drawings.

[0011]

[0018] Referring to FIG. 1, an electric drive unit constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The electric drive unit 10 may include a housing 12, a motor assembly 14, a transmission 16, a differential 18, and a pair of output shafts 20. The motor assembly 14, the transmission 16, and the differential 18 are housed within the housing 12. The motor assembly 14 may include an electric motor 24 and a motor controller 26 having an inverter 28 directly attached to the electric motor 24. The electric motor 24 may include a stator 30 that may be fixedly coupled to the housing 12, a rotor 32 received within the stator 30 and rotatable about a motor shaft 34, and a motor output shaft 36 rotatable with the rotor 32 about the motor shaft 34. The motor output shaft 36 may be fixedly coupled to the rotor 32.

[0012]

[0019] In FIG. 2, the transmission 16 is configured to transmit rotational power between the motor output shaft 36 and the differential device 18. In the illustrated example, the transmission 16 includes an input pinion 40, a pair of first reduction gears 42, a compound gear 44, and an output gear 46. The input pinion 40 can be rotatably coupled to the motor output shaft 36 so as to rotate together around the motor shaft 34. Optionally, the input pinion 40 may be integrally formed with the motor output shaft 36. Each of the first reduction gears 42 is meshed with the input pinion 40 and can be rotatable around a respective first intermediate shaft 50. The first intermediate shaft 50 is parallel to the motor shaft 34 and is disposed in a first plane. Optionally, the motor shaft 34 may be disposed in the first plane. Each of the first reduction gears 42 can be supported by a first bearing 60 and a second bearing 62 so as to rotate around the associated one of the first intermediate shafts 50. The first bearing 60 and the second bearing 62 may be any type of bearing and can be attached to the housing 12 (FIG. 1) and the shaft portion of the first reduction gear 42 in any desired manner. For example, the first bearing 60 and the second bearing 62 may be tapered roller bearings having an outer bearing race fixedly coupled to the housing 12 (FIG. 1), an inner bearing race fixedly coupled to a shaft portion (not shown) of the first reduction gear 42, and a plurality of rollers received between the outer bearing race and the inner bearing race. In the illustrated example, neither the first bearing 60 nor the second bearing 62 is preloaded such that either the rollers of each of the first bearing 60 and the second bearing 62 are in line-to-line contact with the outer bearing race and the inner bearing race or there is a slight clearance between the rollers and at least one of the outer bearing race and the inner bearing race. Alternatively, the first bearing 60 and the second bearing 62 may be axially preloaded.Other types of bearings may be used for the first bearing 60 and the second bearing 62, and the first bearing 60 and the second bearing 62 may be different types of bearings (for example, one may be a certain type of ball bearing such as a radial ball bearing or an angular contact ball bearing, and the other may be a cylindrical roller bearing).

[0013]

[0020] The compound gear 44 is rotatable relative to the housing 12 (FIG. 1) about the second intermediate shaft 70, and includes a second reduction gear 72 and a third reduction gear 74. The second reduction gear 72 is meshed with the first reduction gear 42. The third reduction gear 74 is coupled to the second reduction gear 72 so as to rotate together about the second intermediate shaft 70, and is meshed with the output gear 46. The compound gear 44 can be supported to rotate about the second intermediate shaft 70 by a third bearing (not shown) and a fourth bearing 78. The third bearing and the fourth bearing 78 may be any type of bearing and can be attached to the housing 12 (FIG. 1) and the shaft portion 80 of the compound gear 44 in any desired manner. For example, the third bearing and the fourth bearing 78 may be tapered roller bearings having an outer bearing race fixedly coupled to the housing 12 (FIG. 1), an inner bearing race fixedly coupled to the shaft portion 80 of the compound gear 44, and a plurality of rollers received between the outer bearing race and the inner bearing race. In the illustrated example, neither the third bearing nor the fourth bearing 80 is preloaded such that each roller of the third bearing and the fourth bearing is either in line-line contact with the outer bearing race and the inner bearing race or there is a slight clearance between the roller and at least one of the outer bearing race and the inner bearing race. Alternatively, the third bearing and the fourth bearing may be axially preloaded. Other types of bearings may be used for the third bearing and the fourth bearing, and the third bearing and the fourth bearing may be different types of bearings (for example, one may be a certain type of ball bearing such as a radial ball bearing or an angular contact ball bearing, and the other may be a cylindrical roller bearing).

[0014]

[0021] In the illustrated example, each set of meshing gears within the transmission 16 (i.e., the input pinion 40 and the first reduction gear 42, the first reduction gear 42 and the second reduction gear 44, the third reduction gear 74 and the output gear 46) is formed as a helical gear, but it will be understood that other types of gears, such as spur gears, may be used for one or more of the sets of meshing gears within the transmission 16.

[0015]

[0022] Referring to FIGS. 1 and 2, the differential device 18 includes a differential input portion 90, a pair of differential output portions 92, and a speed difference mechanism 94. The differential input portion 90 can be coupled to the output gear 46 so as to rotate about an output shaft 96 that can be parallel to the motor shaft 34, the first intermediate shaft 50, and the second intermediate shaft 70. The differential output portions 92 can be rotatable about the output shaft 96 relative to the differential input portion 90. The speed difference mechanism 94 is configured to transmit rotational power between the differential input portion 90 and the differential output portions 92 and to allow relative rotation between the differential output portions 92. In one form, the speed difference mechanism 94 can include a pair of friction clutches (not shown) disposed between the differential input portion 90 and the associated one of the differential output portions 92. In other forms, the speed difference mechanism 94 can include a differential gear device between the differential input portion 90 and the differential output portions 92. In the provided example, the differential input portion 90 is a differential carrier, and the speed difference mechanism 94 includes a differential gear device received by the differential carrier. The differential gear device can include a cross pin that is fixedly coupled to the differential carrier and can intersect the output shaft 96 and be disposed perpendicular to the output shaft 96, a pair of differential pinions rotatably mounted to the cross pin, and a pair of side gears that can each be rotatable about the output shaft 96 and meshingly engaged with the differential pinions. In the provided example, each differential output portion 92 is an internally splined hub segment integrally formed together with the associated one of the side gears.

[0016]

[0023] The differential input portion 90 and the output gear 46 can be supported by a fifth bearing (not shown) and a sixth bearing 100 so as to rotate around the output shaft 96. The fifth bearing and the sixth bearing 100 can be any type of bearing and can be attached to the housing 12 (FIG. 1) and one of the differential input portion 90 and the output gear 46 in any desired manner. For example, the fifth bearing and the sixth bearing can be a tapered roller bearing having an outer bearing race fixedly coupled to the housing 12 (FIG. 1), an inner bearing race fixedly coupled to the differential carrier in the example provided, and a plurality of rollers received between the outer bearing race and the inner bearing race. In the illustrated example, neither the fifth bearing nor the sixth bearing is preloaded such that each roller of the fifth bearing and the sixth bearing is either in line-line contact with the outer bearing race and the inner bearing race or there is a slight clearance between the roller and at least one of the outer bearing race and the inner bearing race. Alternatively, the fifth bearing and the sixth bearing can be preloaded axially. Other types of bearings can be used for the fifth bearing and the sixth bearing, and the fifth bearing and the sixth bearing can be different types of bearings (e.g., one can be a certain type of ball bearing such as a radial ball bearing or an angular contact ball bearing, and the other can be a cylindrical roller bearing).

[0017]

[0024] Each output shaft 20 is coupled to the relevant one of the differential output portions 92 so as to rotate around the output shaft 96.

[0018]

[0025] It will be understood that the disengagement mechanism (not shown) can optionally be integrated into the electric drive module 10. The disengagement mechanism is used to selectively interrupt the transmission of rotational power between the electric motor 24 and one or both of the output shafts 20. Examples of suitable disengagement mechanisms are illustrated and described in U.S. Patent Nos. 8,047,323, 8,469,854, 9,028,358, 9,079,495, 9,162,567, and 10,391,861 to the same applicant.

[0019]

[0026] Referring to FIGS. 3 and 4, a second electric drive unit constructed in accordance with the teachings of the present disclosure is shown generally at reference numeral 10a. The electric drive unit 10a is constructed in the same manner as the electric drive unit 10 (FIG. 1), except that the output gear 46 is rotated about the third reduction gear 74 such that the output shaft 96 coincides with the motor shaft 34, and the motor output shaft 36a is hollow such that one of the output shafts 20 is received through the electric motor 24.

[0020]

[0027] Referring to FIGS. 5-7, a portion of a third electric drive unit 10b constructed in accordance with the teachings of the present disclosure is shown. In the illustrated example, the electric motor 24 is positioned such that it is coaxial with the differential 18 and the motor shaft 34 coincides with the output shaft 96. Additionally, the transmission 16b is a two-speed transmission that includes a planetary reduction gear 200 disposed between a second reduction gear 72b and a third reduction gear 74. The planetary reduction gear 200 includes a ring gear 202, a sun gear 204, a planetary carrier 206, and a plurality of planetary gears 208. The ring gear 202 is coupled to the second reduction gear 72b for co-rotation and includes a plurality of inner gear teeth. In the example provided, the ring gear 202 and the second reduction gear 72a are fixedly coupled to each other (e.g., integrally formed together). The sun gear 204 is coaxially disposed about a shaft portion 80a, is rotatable on a shaft portion 80b, and is further axially slidably disposed on the shaft portion 80a. In the example provided, the sun gear 204 defines a shaft opening that is attached to a cylindrical segment of the shaft portion 80b. The shaft portion 80a can be rotatably coupled (e.g., fixedly coupled) to the third reduction gear 74 in any desired manner. The planetary carrier 206 includes a carrier body 220 (FIG. 6) and a plurality of pins 222 (FIG. 7) that are fixedly coupled to the carrier body 220 and circumferentially spaced about a second intermediate shaft 70. The carrier body 220 can be coupled to the shaft portion 80b for co-rotation about the second intermediate shaft 70. In the example provided, the carrier body 220 includes a first body member that is fixedly coupled (e.g., integrally formed therewith) to the shaft portion 80b and extends radially outward therefrom, and a second body member having an annular shape and spaced axially away from the first body member along the second intermediate shaft 70. Axially opposite ends of the pins 222 can be fixedly coupled to the first and second body members. Each planetary gear 208 is rotatably disposed on a corresponding one of the pins 222 and meshingly engaged with the ring gear 202 and the sun gear 204.

[0021]

[0028] The sun gear 204 can move axially along the second intermediate shaft 70 between a first position shown in FIG. 6 and a second position shown in FIG. 8. The arrangement of the sun gear 204 in the first position causes the planetary speed reducer 200 to perform a speed reduction and torque multiplication function between the second reduction gear 72a and the shaft portion 80a. The arrangement of the sun gear 204 in the second position locks the sun gear 204 in the rotational direction with respect to the planetary carrier 206, and effectively prevents relative rotation between the planetary carrier 206 and between the sun gear 204 and the ring gear 202 so that the output part of the planetary speed reducer 200 (i.e., the planetary carrier 206 in the provided example) rotates at the same rotational speed as the input part of the planetary speed reducer 200 (i.e., the ring gear 202 in the provided example).

[0022]

[0029] Any type of actuator can be used to control the movement of the sun gear 204 along the second intermediate shaft 70. For example, a spring (not shown) may be used to bias the sun gear 204 in a predetermined direction along the intermediate shaft 70 towards either the first position or the second position. In the provided example, a shift fork 230 is provided, and the shift fork 230 has a pair of teeth 232 received in an annular groove 234 formed on the outer periphery of the hub portion 236 of the sun gear 204. The shift fork 230 can be moved along the second intermediate shaft 70 by any desired means such as a solenoid, a pneumatic cylinder or a hydraulic cylinder.

[0023]

[0030] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and can be used in the selected embodiment if applicable, even if not specifically illustrated or described. The same can also be modified in many ways. Such modifications should not be regarded as a departure from the disclosure, and all such corrections are intended to be included within the scope of the disclosure.

Claims

1. An electric drive unit comprising: an electric motor having a motor output shaft rotatable about a first axis of rotation; an input pinion driven by the motor output shaft about the first axis of rotation; a pair of first reduction gears meshing with the input pinion, each of the first reduction gears being rotatable about a respective second axis of rotation parallel to the first axis of rotation; a second reduction gear meshing with the first reduction gears, the second reduction gear being parallel to the first and second axes of rotation and rotatable about a third axis of rotation offset from the first and second axes of rotation; a third reduction gear driven by the second reduction gear, the third reduction gear being rotatable about the third axis of rotation; a fourth reduction gear meshing with the third reduction gear, the fourth reduction gear being rotatable about a fourth axis of rotation parallel to the second and third axes of rotation; a differential assembly having a differential input and a pair of differential outputs, the differential input being coupled to the third reduction gear so as to rotate together about the fourth axis of rotation, each of the differential outputs being driven by the differential input and rotatable about the fourth axis of rotation; An electric drive unit comprising the above components.

2. The electric drive unit according to claim 1, further comprising a planetary reduction gear disposed between the second reduction gear and the third reduction gear, the planetary reduction gear having a planetary input coupled to the second reduction gear so as to rotate together and a planetary output coupled to the third reduction gear so as to rotate together.

3. The electric drive unit according to claim 2, wherein the planetary reduction gear is at least partially received within the second reduction gear.

4. The electric drive unit according to claim 3, wherein the planetary input is a ring gear fixedly coupled to the second reduction gear.

5. The electric drive unit according to claim 4, wherein the ring gear and the second reduction gear are integrally formed together.

6. The electric drive unit according to claim 2, wherein the planetary reduction gear is a two-speed reduction gear.

7. The planetary speed reducer includes a sun gear, a planetary carrier, and a plurality of planetary gears, the planetary carrier pivotally supporting each of the planetary gears for rotation about its respective planetary gear axis, each of the planetary gears being meshed and engaged with the sun gear, wherein one of the planetary carrier and the sun gear is axially movable along the third rotation axis between a first position in which relative rotation between the planetary carrier and the sun gear is enabled and a second position in which relative rotation between the planetary carrier and the sun gear is blocked, the electric drive unit according to claim 6.

8. The electric drive unit according to claim 2, wherein the first rotation axis coincides with the fourth rotation axis.

9. The electric drive unit according to claim 1, wherein the first rotation axis coincides with the fourth rotation axis.

10. The electric drive unit according to claim 1, further comprising an inverter directly attached to the electric motor.

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