Electric drive device

Abstract

An electric drive device has an electric motor, an input pinion driven by an output shaft of the electric motor about a first axis, a pair of first gears each meshing with the input pinion and rotatable about a respective second axis, a second gear meshing with the first gears and rotatable about a third axis, the third gear is driven by the second gear around the third axis; the fourth gear is meshed with the third gear and can rotate around the fourth axis; the differential has a differential input rotatably coupled to the third gear and a pair of differential outputs driven by the differential input and rotatable about the fourth axis. The first axis, the second axis, the third axis and the fourth axis are parallel to one another. The third axis is offset from the first axis and the second axis.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 357,058, filed on June 30, 2022, the disclosure of which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The present disclosure relates to an electric drive device. Background Art

[0004] This section provides background information related to the present disclosure which is not necessarily prior art.

[0005] U.S. Patent No. 11293534 discloses an electric drive module having a relatively compact transmission configured to provide a relatively high overall reduction ratio between an output shaft of an electric motor and an output of the transmission. While such a transmission is suitable for its intended purpose, there remains a need in the art for a relatively compact transmission that provides a relatively high overall reduction ratio. Summary of the invention

[0006] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0007] In one form, the present disclosure provides an electric drive device, including a 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 motor has a motor output shaft rotatable around a first rotation axis. The input pinion is driven by the motor output shaft around the first rotation axis. Each of the first reduction gears is meshingly engaged with the input pinion and is rotatable around a corresponding second rotation axis parallel to the first rotation axis. The second reduction gear is meshingly engaged with the first reduction gear and is rotatable around a third rotation axis parallel to and offset from the first rotation axis and the second rotation axis. The third reduction gear is driven by the second reduction gear around the third rotation axis. The fourth reduction gear is meshingly engaged with the third reduction gear and is rotatable around a fourth rotation axis parallel to the second rotation axis and the third rotation axis. 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 with it around the fourth rotation axis. Each of the differential outputs is driven by the differential input and is rotatable about the fourth axis of rotation.

[0008] Further areas of applicability 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0010] Figure 1 are perspective and partial cross-sectional views of an exemplary electric drive device constructed in accordance with the teachings of the present disclosure;

[0011] Figure 2 yes Figure 1 A perspective view of a transmission of an electric drive device;

[0012] Figure 3 is a front elevational view, partially in section, of a second exemplary electric drive device constructed in accordance with the teachings of the present disclosure;

[0013] Figure 4 yes Figure 3 A perspective view of a transmission of an electric drive device;

[0014] Figure 5 is a perspective view of a portion of a third electric drive device constructed in accordance with the teachings of the present disclosure;

[0015] Figure 6 yes Figure 5 A longitudinal sectional view of a portion of an electric drive device of the embodiment of the present invention, the view depicting the sun gear of the planetary reducer in a first position;

[0016] Figure 7 It is along Figure 5 A cross-sectional view taken along line 7-7 in FIG. 1 ; and

[0017] Figure 8 is with Figure 6 A similar view but depicting the sun gear of the planetary reducer in a second position.

[0018] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0019] refer to Figure 1, an electric drive device constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The electric drive device 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 in the housing 12. The motor assembly 14 may include a motor 24 and a motor controller 26 having an inverter 28 mounted directly to the motor 24. The motor 24 may include a stator 30, which may be fixedly coupled to the housing 12, a rotor 32 received in the stator 30 and rotatable about the motor axis 34, and a motor output shaft 36, which may rotate with the rotor 32 about the motor axis 34. The motor output shaft 36 may be fixedly coupled to the rotor 32.

[0020] exist Figure 2 , the transmission 16 is configured to transfer rotational power between the motor output shaft 36 and the differential 18. In the example shown, 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 to rotate with it around the motor axis 34. Optionally, the input pinion 40 can be formed integrally with the motor output shaft 36. Each first reduction gear 42 can be meshed with the input pinion 40 and can rotate around a respective first intermediate axis 50. The first intermediate axis 50 is parallel to the motor axis 34 and is disposed in a first plane. Optionally, the motor axis 34 can be disposed in a first plane. Each first reduction gear 42 can be supported by a first bearing 60 and a second bearing 62, respectively, to rotate around an associated one of the first intermediate axes 50. The first bearing 60 and the second bearing 62 can be any type of bearing and can be mounted to the housing 12 ( Figure 1 ) and the shaft portion of the first reduction gear 42. For example, the first bearing 60 and the second bearing 62 may be tapered roller bearings having a fixed connection to the housing 12 ( Figure 1), an outer bearing race of the first reduction gear 42, 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 example shown, neither the first bearing 60 nor the second bearing 62 is preloaded, so that 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 small amount of 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 can be preloaded in the axial direction. It will be understood that other types of bearings can be used for the first bearing 60 and the second bearing 62, and the first bearing 60 and the second bearing 62 can be different types of bearings (for example, one can be a ball bearing type, such as a radial ball bearing or an angular contact ball bearing, and the other can be a cylindrical roller bearing).

[0021] The composite gear 44 can be relative to the housing 12 ( Figure 1 ) rotates around the second intermediate axis 70, and includes a second reduction gear 72 and a third reduction gear 74. The second reduction gear 72 is meshingly engaged to the first reduction gear 42. The third reduction gear 74 is coupled to the second reduction gear 72 to rotate therewith around the second intermediate axis 70, and is meshingly engaged with the output gear 46. The composite gear 44 can be supported by a third bearing (not shown) and a fourth bearing 78 to rotate around the second intermediate axis 70. The third bearing and the fourth bearing 78 can be any type of bearing and can be mounted to the housing 12 (in any desired manner). Figure 1 ) and the shaft portion 80 of the composite gear 44. For example, the third bearing and the fourth bearing 78 may be tapered roller bearings having a fixed connection to the housing 12 ( Figure 1 ), an outer bearing race of the shaft portion 80 fixedly coupled to the compound gear 44, and a plurality of rollers received between the outer bearing race and the inner bearing race. In the example shown, neither the third bearing nor the fourth bearing 80 is preloaded, such that the rollers of each of the third bearing and the fourth bearing are in line-to-line contact with the outer bearing race and the inner bearing race, or there is a small amount of clearance between the rollers and at least one of the outer bearing race and the inner bearing race. Alternatively, the third bearing and the fourth bearing may be preloaded in the axial direction. It will be understood that other types of bearings may be used for the third bearing and the fourth bearing, and that the third bearing and the fourth bearing may be different types of bearings (e.g., one may be a ball bearing type, such as a radial ball bearing or an angular contact ball bearing, and the other may be a cylindrical roller bearing).

[0022] In the example shown, each set of meshing gears in 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 gear types such as spur gears may be used for one or more sets of meshing gears in the transmission 16.

[0023] refer to Figure 1 and Figure 2 , the differential 18 includes a differential input 90, a pair of differential outputs 92, and a differential mechanism 94. The differential input 90 can be coupled to the output gear 46 to rotate about an output axis 96, which can be parallel to the motor axis 34, the first intermediate axis 50, and the second intermediate axis 70. The differential output 92 can rotate about the output axis 96 relative to the differential input 90. The differential mechanism 94 is configured to transfer rotational power between the differential input 90 and the differential output 92, and to allow relative rotation between the differential outputs 92. In one form, the differential mechanism 94 can include a pair of friction clutches (not shown) disposed between the differential input 90 and the associated one of the differential outputs 92. In another form, the differential mechanism 94 can include a differential transmission between the differential input 90 and the differential output 92. In the example provided, the differential input 90 is a differential carrier, and the differential mechanism 94 includes a differential transmission received in the differential carrier. The differential gearing may include a cross pin that may be fixedly coupled to the differential carrier and may intersect and be disposed perpendicularly to the output axis 96, a pair of differential pinions rotatably mounted on the cross pin, and a pair of side gears that are each rotatable about the output axis 96 and meshingly engaged with the differential pinions. In the example provided, each differential output 92 is an internally splined hub segment integrally formed on an associated one of the side gears.

[0024] The differential input 90 and the output gear 46 may be supported by a fifth bearing (not shown) and a sixth bearing 100 for rotation about the output axis 96. The fifth bearing and the sixth bearing 100 may be any type of bearing and may be mounted to the housing 12 ( Figure 1 ) and one of the differential input 90 and output gear 46. For example, the fifth bearing and the sixth bearing may be tapered roller bearings having a fixed connection to the housing 12 ( Figure 1) of the differential carrier, 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 example shown, neither the fifth bearing nor the sixth bearing is preloaded, such that the rollers of each of the fifth bearing and the sixth bearing are in line-to-line contact with the outer bearing race and the inner bearing race, or there is a small amount of clearance between the rollers and at least one of the outer bearing race and the inner bearing race. Alternatively, the fifth bearing and the sixth bearing may be preloaded in the axial direction. It will be understood that other types of bearings may be used for the fifth bearing and the sixth bearing, and that the fifth bearing and the sixth bearing may be different types of bearings (e.g., one may be a ball bearing type, such as a radial ball bearing or an angular contact ball bearing, and the other may be a cylindrical roller bearing).

[0025] Each output shaft 20 is coupled with an associated one of the differential outputs 92 for rotation about an output axis 96 .

[0026] It will be appreciated that a disconnect mechanism (not shown) may optionally be integrated into the electric drive module 10. The disconnect mechanism is used to selectively interrupt the transmission of rotational power between the motor 24 and one or both of the output shafts 20. Examples of suitable disconnect mechanisms are illustrated and described in commonly assigned U.S. Patent Nos. 8,047,323, 8,469,854, 9,028,358, 9,079,495, 9,162,567, and 10,391,861.

[0027] refer to Figure 3 and Figure 4 A second electric drive device constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10a. Electric drive device 10a is similar to electric drive device 10 ( Figure 1 ) is constructed in the same manner, except that the output gear 46 rotates about the third reduction gear 74 so that the output axis 96 coincides with the motor axis 34, and the motor output shaft 36a is hollow so that one of the output shafts 20 is received through the motor 24.

[0028] refer to Figures 5 to 7, illustrating a portion of a third electric drive device 10b constructed according to the teachings of the present disclosure. In the example shown, the motor 24 is arranged so that it is coaxial with the differential 18, and the motor axis 34 and the output axis 96 coincide. In addition, the transmission 16b is a two-speed transmission including a planetary reducer 200 disposed between the second reduction gear 72b and the third reduction gear 74. The planetary reducer 200 includes a ring gear 202, a sun gear 204, a planet carrier 206, and a plurality of planetary gears 208. The ring gear 202 is coupled to the second reduction gear 72b to rotate therewith, and includes a plurality of internal 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). The sun gear 204 is concentrically disposed around the shaft portion 80a, and can be rotated on the shaft portion 80b, and can also be axially slidably disposed on the shaft portion 80a. In the example provided, the sun gear 204 defines a shaft opening mounted on a cylindrical section of the shaft portion 80b. The shaft portion 80a can be rotatably coupled (eg, fixedly coupled) to the third reduction gear 74 in any desired manner. The planet carrier 206 includes a carrier body 220 ( Figure 6 ) and a plurality of pins 222 ( Figure 7 ). The carrier body 220 can be coupled to the shaft portion 80b to rotate together about the second intermediate axis 70. In the example provided, the carrier body 220 includes a first body member and a second body member, the first body member is fixedly coupled to the shaft portion 80b (e.g., formed integrally with the shaft portion 80b) and extends radially outward from the shaft portion 80b, and the second body member has an annular shape and is axially spaced apart from the first body member along the second intermediate axis 70. The opposite axial ends of the pin 222 can be fixedly coupled to the first body member and the second body member. Each planet gear 208 is rotatably disposed on a corresponding one of the pins 222 and meshingly engaged to the ring gear 202 and the sun gear 204.

[0029] The sun gear 204 can be located along the second intermediate axis 70. Figure 6 The first position shown in Figure 8axially between the second position shown in . Placing the sun gear 204 in the first position causes the planetary reducer 200 to perform a speed reduction and torque multiplication function between the second reduction gear 72a and the shaft portion 80a. Placing the sun gear 204 in the second position rotatably locks the sun gear 204 to the planet carrier 206 and effectively inhibits relative rotation between the planet carrier 206, the sun gear 204 and the ring gear 202, so that the output of the planetary reducer 200 (i.e., the planet carrier 206 in the example provided) rotates at the same speed as the input of the planetary reducer 200 (i.e., the ring gear 202 in the example provided).

[0030] Any type of actuator may be used to control the movement of the sun gear 204 along the second intermediate axis 70. For example, a spring (not shown) may be used to bias the sun gear 204 toward the first position or the second position along the intermediate axis 70 in a predetermined direction. In the example provided, a shift fork 230 is provided having a pair of pointed teeth 232 received in an annular groove 234 formed around the circumference of a hub portion 236 of the sun gear 204. The shift fork 230 may be moved along the second intermediate axis 70 by any desired means such as a solenoid, a pneumatic cylinder, or a hydraulic cylinder.

[0031] The above description of the embodiment has been provided for the purpose of illustration and description. It is not intended to be exhaustive or limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but when applicable, they are also interchangeable and can be used in selected embodiments even if not specifically shown or described. The same situation may also change in many ways. These changes should not be considered as departing from the present disclosure, and all these modifications are intended to be included in the scope of the present disclosure.

Claims

1. An electric drive device, comprising: an electric motor having a motor output shaft rotatable about a first rotation axis; an input pinion gear driven about the first rotation axis by the motor output shaft; a pair of first reduction gears meshingly engaged with the input pinion, each of the first reduction gears being rotatable about a respective second rotation axis parallel to the first rotation axis; a second reduction gear meshingly engaged with the first reduction gear, the second reduction gear being rotatable about a third rotation axis parallel to and offset from the first rotation axis and the second rotation axis; a third reduction gear driven by the second reduction gear, the third reduction gear being rotatable around the third rotation axis; a fourth reduction gear meshingly engaged with the third reduction gear, the fourth reduction gear being rotatable about a fourth rotation axis parallel to the second rotation axis and the third rotation axis; and A differential assembly has a differential input coupled to the third reduction gear to rotate therewith about the fourth axis of rotation, and a pair of differential outputs, each of which is driven by the differential input and rotatable about the fourth axis of rotation.

2. The electric drive device according to claim 1 further includes a planetary reducer arranged between the second reduction gear and the third reduction gear, the planetary reducer having a planetary input connected to the second reduction gear to rotate therewith and a planetary output connected to the third reduction gear to rotate therewith. 3 . The electric drive device according to claim 2 , wherein the planetary reducer is at least partially accommodated in the second reduction gear.

4. The electric drive device of claim 3, wherein the planetary input is a ring gear fixedly coupled to the second reduction gear. 5 . The electric drive device according to claim 4 , wherein the ring gear and the second reduction gear are integrally formed.

6. The electric drive device according to claim 2, wherein the planetary reducer is a two-speed reducer.

7. An electric drive device according to claim 6, wherein the planetary reducer includes a sun gear, a planet carrier and a plurality of planet gears, the planet carrier axially supports each of the planet gears to rotate around a corresponding planet gear axis, each of the planet gears is meshingly engaged with the sun gear, wherein the planet carrier and one of the sun gears can move axially along the third rotation axis between a first position allowing relative rotation between the planet carrier and the sun gear and a second position prohibiting relative rotation between the planet carrier and the sun gear.

8. The electric drive device of claim 2, wherein the first rotation axis and the fourth rotation axis coincide.

9. The electric drive device of claim 1, wherein the first rotation axis and the fourth rotation axis coincide.

10. The electric drive device of claim 1, further comprising an inverter mounted directly to the electric motor.

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