WO2022246054A1

WO2022246054A1 - Electric drive module for driving a vehicle wheel

Info

Publication number: WO2022246054A1
Application number: PCT/US2022/030013
Authority: WO
Inventors: Derek C. REMILLONG; Robert Chisholm; Thomas C. PAULCH; James P. KULKA; He NIU; Sean M. STANLEY; Gregory A. Marsh
Original assignee: American Axle & Manufacturing, Inc.
Priority date: 2021-05-20
Filing date: 2022-05-19
Publication date: 2022-11-24

Abstract

An electric drive unit with a transmission and an output shaft. The transmission includes an input pinion, an output gear and a pair of compound gears that are drivingly disposed between the input pinion and the output gear. The output gear includes a hub and a gear portion having teeth that are disposed circumferentially about the hub. The hub defines an internally splined segment and a pair of bearing mounts onto which a pair of bearings are mounted. The teeth of the gear portion are located along the output axis between the first and second circumferential bearing surfaces. The internally splined segment is engaged with an externally splined segment on the output shaft.

Description

ELECTRIC DRIVE MODULE FOR DRIVING A VEHICLE WHEEL

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S Provisional Patent Application No. 63/190975 filed May 20, 2021 , the disclosure of which is incorporated by reference as if set forth in its entirety herein.

FIELD

[0002] The present disclosure relates to an electric drive module that is configured to drive a vehicle wheel.

BACKGROUND

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

[0004] One form of an electrically driven vehicle employs wheel motors at each of the vehicle wheels that is to be driven. Wheel motors are advantageous in that each of the driven vehicle wheels can be independently controlled to provide enhanced traction and handling capabilities for the vehicle. The use of wheel motors, however, is undesirable as they increase the un-sprung mass of the vehicle, which adversely affects road grip when tracking over an imperfect road surface.

[0005] Another form of electrically driven vehicle employs an electric motor that drives a pair of vehicle wheels through a transmission and a differential. The electric motor, transmission and differential are mounted to the chassis of the vehicle and thereby permit a reduction in the un-sprung mass of the vehicle relative to a configuration that employs wheel motors. However, because a single motor is providing electric power to two driven wheels through a differential, the independent control of the driven vehicle wheels can be more costly and complex relative to a configuration that employs wheel motors.

[0006] Accordingly, there remains a need in the art for an electrically driven vehicle that permits independent control of the driven wheels of the vehicle and which does not significant increase the un-sprung mass of the vehicle. SUMMARY

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In one form, the present disclosure provides an electric drive unit that includes a housing, a motor assembly, a transmission, first and second hub bearings, and an output shaft. The motor assembly is coupled to the housing and includes an electric motor with a motor output shaft that is rotatable about a motor axis. The transmission is received in the housing and includes an input pinion, an output gear and a pair of compound gears. The input pinion is coupled to the motor output shaft for rotation therewith. The output gear is rotatable about an output axis. Each of the compound gears has a first intermediate gear, which is meshingly engaged with the input pinion, and a second intermediate gear that is meshingly engaged with the output gear and coupled to the first intermediate gear for rotation therewith. The output gear has a hub and a gear portion. The hub defines an internally splined segment, a first bearing mount, and a second bearing mount. The first bearing mount has a first circumferential bearing surface and a first shoulder. The second bearing mount has a second circumferential bearing surface and a second shoulder. The first hub bearing is mounted to the housing and has a first inner bearing race that is received on the first circumferential bearing surface and abuts the first shoulder. The second hub bearing is mounted to the housing and has a second inner bearing race that is received on the second circumferential bearing surface and abuts the second shoulder. The gear portion has a plurality of gear teeth and extends radially outwardly from the hub at a location along the output axis that is between the first and second circumferential bearing surfaces. The internally splined segment being engaged with an externally splined segment on the output shaft to thereby rotatably couple the output shaft to the hub.

[0009] 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. DRAWINGS

[0010] 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. [0011] Figure 1 is a perspective view of an exemplary electric drive module constructed in accordance with the teachings of the present disclosure;

[0012] Figure 2 is a section view taken along the line 2-2 of Figure 1 ;

[0013] Figures 3 and 4 are exploded perspective views of a portion of the electric drive module of Figure 1 illustrating a portion of a housing assembly, a transmission and an output member in more detail;

[0014] Figure 5 is a section view of a portion of the electric drive module of Figure 1 taken along a longitudinal axis of the output member;

[0015] Figure 6 is a perspective view of another exemplary electric drive module constructed in accordance with the teachings of the present disclosure; [0016] Figure 7 is a section view taken along the line 7-7 of Figure 1 ;

[0017] Figure 8 is an exploded perspective view of a portion of the electric drive module of Figure 6;

[0018] Figure 9 is a perspective view of a portion of the electric drive module of Figure 6, the view illustrating a transmission; [0019] Figure 10 is a section view taken along the line 10-10 of Figure 1; and

[0020] Figure 11 is an enlarged portion of Figure 10.

[0021] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0022] With reference to Figures 1 and 2, an exemplary electric drive module (EDM) constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The EDM 10 can include a housing assembly 12, a motor assembly 14, a cooling and lubrication system 16, a transmission 18 and an output member 20. The housing assembly 12 can include a motor housing 30 and a gearcase 32. The motor assembly 14 can be received into the motor housing 30, while the transmission 18 can be received into the gearcase 32. The motor assembly 14 can include an electric motor 40 and a motor controller 42 having an inverter 44. The cooling and lubrication system 16 can include a pump 50, a pressure filter 52, and a heat exchanger 54 and can employ various galleries and passages (not shown) in the housing assembly 12 and the electric motor 40 to cool various components of the EDM 10, such as a stator 56 and a rotor 58 of the electric motor 40 and the inverter 44, and to lubricate various elements of the electric motor, such as bearings (not shown) that support the rotor 58, and elements of the transmission 18, such as bearings and gear teeth). Generally speaking, and except as noted herein, the housing assembly 12, the motor assembly 14 and the cooling and lubrication system 16 can be constructed and operated in a manner that is described in co-pending, co-assigned U.S. Provisional Patent Application No. 63/161164 filed March 15, 2021, the disclosure of which is incorporated by reference as if fully set forth in detail herein. The transmission 18 is configured to transmit rotary power between a motor output shaft 82 of the electric motor 40 and the output member 20 and can be configured in any desired manner, for example with one or more reductions. The reduction(s) of the transmission 18 can be formed by one or more planetary stages (e.g., epicyclic, Ravigneaux), and/or one or more stages of meshing gears having parallel rotational axes (e.g., spur gears, helical gears) and/or one or more stages of meshing gears having non-parallel rotational axes (e.g., bevel gears, spiral gears, hypoid gears, worm gears). Accordingly, it will be appreciated that the transmission could be configured in a manner that is described in more detail in International Patent Application No. PCT/US2020/062541 filed November 30, 2020, U.S. Provisional Patent Application No. 62/942496 filed December 2, 2019, and/or U.S. Provisional Patent Application No. 63/161164 filed March 15, 2021 , the disclosures of each of which is incorporated by reference as if fully set forth in detail herein.

[0023] With reference to Figures 2 and 3, the gearcase 32 comprises a first gearcase portion 60, which is fixedly coupled to the motor housing 30, and a second gearcase portion 62 that is mounted to the first gearcase portion 60 and fixedly coupled thereto via a plurality of threaded fasteners 64. The first and second gearcase portions 60 and 62 define a cavity 66 into which the transmission 18 is received. A portion of the cavity 66 can form a sump 66s that can hold a quantity of fluid that can be used as the lubricant and optionally as the coolant that is circulated by the cooling and lubrication system 16 (Fig. 1). The pump 50 (Fig. 1) can be mounted to the first gearcase portion 60 and can receive fluid from the sump 66s. The first gearcase portion 60 can define a motor shaft aperture 70, a motor shaft bearing bore 72, which is disposed concentrically about the motor shaft aperture 70 on a side of the first gearcase portion 60 that faces the second gearcase portion 62, and a first bearing bore 74, while the second gearcase portion 62 can define a second bearing bore 76 and an output member aperture 78. A motor shaft bearing 80 can be received into the motor shaft bearing bore 72 and can support the output shaft 82 of the electric motor 40 for rotation about an input axis 84 relative to the housing assembly 12. A retaining ring 86 can be fitted into a groove 88 that is formed into the circumferentially extending wall in the first gearcase portion 60 that forms the motor shaft aperture 70. The retaining ring 86 can inhibit removal of the motor shaft bearing 80 from the motor shaft bearing bore 72.

[0024] With reference to Figures 3-5, the transmission 18 of the particular example provided includes an input pinion 90, an intermediate gear 92, a planetary gearset 94 and a transmission output 96. The input pinion 90 can be a helical gear and can be coupled for rotation with the motor output shaft 82 so as to be rotatable about the input axis 84. The intermediate gear 92 is meshingly engaged with the input pinion 90 and is rotatable about an output axis 100. The intermediate gear 92 can be coupled for rotation with a shaft member 102. The shaft member 102 can be supported for rotation about the output axis 100 relative to the first gearcase portion 60 by a first bearing 104. The first bearing 104 can be received in the first bearing bore 74. In the example provided, the shaft member 102 and the intermediate gear 92 are formed as discrete components and are fixedly coupled to one another, for example via welding (e.g., friction welding, laser welding) and/or threaded fasteners (not shown) and/or a press or interference fit between the shaft member 102 and the intermediate gear 92. The shaft member 102 can include a stepped flange 110 having a first circumferential surface 112, a second circumferential surface 114 that is larger in diameter than the first circumferential surface 112, and a first shoulder 116 that extends radially between the first and second circumferential surfaces 112 and 114. The intermediate gear 92 can define a stepped aperture 120 having a third circumferential surface 122, a fourth circumferential surface 124 that is larger in diameter than the third circumferential surface 122, and a second shoulder 126 that extends radially between the third and fourth circumferential surfaces 122 and 124. The stepped flange 110 can be received into the stepped aperture 120 and the first shoulder 116 can be abutted against the second shoulder 126. The fit between the first circumferential surface 112 and the third circumferential surface 122, and/or the fit between the second circumferential surface 114 and the fourth circumferential surface 124 can align the shaft member 102 and the intermediate gear 92 to one another about a common rotational axis.

[0025] The planetary gearset 94 can include a sun gear 130, a ring gear 132, a planet carrier 134 and a plurality of planet gears 136. The sun gear 130 can be a helical gear that can be coupled to the intermediate gear 92 for rotation therewith about the output axis 100. In the example provided, the sun gear 130 is unitarily and integrally formed with the shaft member 102. The ring gear 132 can be disposed concentrically about the sun gear 130 and can be non-rotatably coupled to the second gearcase portion 62. For example, the ring gear 132 can be formed with a plurality of external spline teeth (not shown) that can be received into corresponding grooves (not shown) formed into the second gearcase portion 62 to non-rotatably couple the ring gear 132 to the second gearcase portion 62. The planet carrier 134 can include a carrier body 150 and a plurality of pins 152. The carrier body 150 can include first and second carrier plates 156 and 158, respectively. The first carrier plate 156 can have a first annular plate member 160 and a plurality of spacing legs 162 that can extend from one axial side of the first annular plate member 160. The first annular plate member 160 has an aperture 166 formed therethrough that is sized to receive the sun gear 130. If desired, a thrust bearing 168 can be disposed along the output axis 100 between the first carrier plate 156 and either the stepped flange 110 on the shaft member 102 or the intermediate gear 92. The second carrier plate 158 can have a second annular plate member 170. The spacing legs 162 on the first carrier plate 156 can abut the second annular plate member 170 and can operably space the first and second carrier plates 156 and 158 apart from one another by a desired distance. Each of the pins 152 can be fitted through corresponding pin apertures 180 in the first and second plate members 160 and 170 and can fixedly couple the first and second carrier plates 156 and 158 to one another. Each of the planet gears 136 can be rotatably disposed on a corresponding one of the pins 152 and can be meshingly engaged with the sun gear 130 and the ring gear 132.

[0026] The transmission output 96 can be coupled to the carrier body 150 for rotation therewith. In the example provided, the transmission output 96 is an internally splined hub that is unitarily and integrally formed with the second annular plate member 170 and which extends along the output axis 100 in a direction away from the first carrier plate 156. [0027] In the example provided, the output member 20 of the EDM 10 is a relatively short shaft having a first externally-splined end 200, which is received into an engaged with the internal splines that are formed onto the transmission output 96, a second externally-splined end 202, and a bearing mount 204 that is disposed along the output axis 100 between the first and second externally-splined ends 200 and 202. The output member 20 can be sized to extend through the output member aperture 78 in the second gearcase portion 62 such that the second externally-splined end 202 is disposed wholly outside of the gearcase 32. A second bearing 210 can be mounted on the bearing mount 204 and can be received in a second bearing bore 76 that is formed in the second gearcase portion 62. The second bearing 210 can support the output member 20 for rotation about the output axis 100 relative to the gearcase 32. A retaining ring (not specifically shown) can be received in a groove (not shown) formed in the transmission output 96 and in a groove 214 in the output member 20 to inhibit relative motion along the output axis 100 between the transmission output 96 and the output member 20. A seal 220 can be received into a seal bore 222 that is formed in an exterior surface of the second gearcase portion 62 concentrically about the output member aperture 78. The seal 220 can be sealingly engaged to the second gearcase portion 62 and the output member 20. A half-shaft (not shown) having constant velocity joints (not shown) on opposite ends of a shaft (not shown) can be employed to drivingly couple the output member 20 to a wheel hub (not shown) to permit the EDM 10 to provide rotary power to drive a corresponding wheel of a vehicle (not shown). The EDM 10 can be mounted to the chassis (not shown) of the vehicle, thereby forming a portion of the "sprung mass" of the vehicle.

[0028] Optionally, pressurized fluid in the cooling and lubrication system 16 can be transmitted through the housing assembly 12 to the first bearing 104 and to a passage (not shown) in the shaft member 102 that extends along the output axis 100. Fluid transmitted into the passage in the shaft member 102 can be discharged into a pocket 250 in the second carrier plate 158 that is disposed between an axial end of the output member 20 and an axial end of the sun gear 130 that faces the output member 20. Fluid in the pocket 250 can lubricate the meshing teeth of the sun gear 130 and the planet gears 136, as well as lubricate between the pins 152 and the planet gears 136. Lubrication apertures 252 can optionally be formed through the carrier body 150 to permit lubrication to flow through the planet carrier 134 to the second bearing 210. [0029] With reference to Figures 6 and 7, another exemplary EDM constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10a. Except as described herein, the EDM 10a is generally similar to the EDM 10 (Fig. 1) as it includes a housing assembly 12, a motor assembly 14, and a cooling and lubrication system 16 that are substantially similar (if not identical) to those that are discussed in detail above and shown in Figures 1 -5. The transmission 18a and the output member 20a are somewhat different than those that are described above and illustrated in Figures 1-5.

[0030] With reference to Figures 8 through 10, the transmission 18a can be generally similar to that which is described in International Patent Application No. PCT/US2020/062541. In this regard, the transmission 18a can include an input pinion 90a, a pair of compound gears 300, and an output gear 96a. The input pinion 90a can be fixedly coupled to the output shaft 82 of the electric motor 40 for rotation about the input axis 84 relative to the housing assembly 12. Each of the compound gears 300 includes a first intermediate gear 304, and a second intermediate gear 306. The first intermediate gear 304 can be rotatable about a respective intermediate axis 310 and can be meshingly engaged with the input pinion 90a. The second intermediate gear 306 can be coupled to the first intermediate gear 304 for rotation therewith about the intermediate axis 310 and can be meshingly engaged to the output gear 96a. In the particular embodiment shown, the first and second intermediate gears 304 and 306 of each compound gear 300 are fixedly coupled to a shaft member 312 that is supported for rotation relative to the housing assembly 12 by a pair of bearings 314. Each of the bearings 314 can be mounted into a respective one of the first and second gearcase portions 60 and 62. In the example provided, the first and second intermediate gears 304 and 306 are helical gears and as such, a thrust load (i.e., a load directed along the intermediate axis 310) can be generated when rotary power is transmitted through the transmission 18a. The bearings 314 can be configured to handle the radial and thrust loads. As shown, the bearings 314 are tapered roller bearings, but it will be appreciated that other types of bearings could be employed, including angular contact bearings. The output gear 96a is rotatable about the output axis 100 and is the output of the transmission 18a in the example provided.

[0031] The output member 20a can be coupled for rotation with the output gear 96a. In the example provided, the output member 20a is integrally and unitarily formed with the output gear 96a. In this regard, the output gear 96a can include a gear portion (i.e., the gear teeth 320 that are formed about the circumference of the output gear 96a) and a hub (i.e., the output member 20a).

[0032] In Figure 11 , the hub 20a can define an internally splined segment 340, a first bearing mount 342, and a second bearing mount 344. Optionally, the hub 20a can define a blind hole 348 and the plurality of spline teeth 350 of the internally splined segment 340 can be formed on a surface of the blind hole 348. The internally splined segment 340 is configured to axially slidably but non-rotatably engage with an externally splined segment 360 that is formed on an output shaft 362 that is drivingly coupled to a drive wheel (not shown). A first ring groove 370 can be formed in the internally splined segment 340 and a second ring groove 372 can be formed in the externally splined segment 360. A retaining ring 380 (Fig. 8) can be received in the first and second ring grooves 370 and 372. The retaining ring 380 (Fig. 8) can resist movement of the externally splined segment 360 of the output shaft 362 axially along the output axis 100 relative to the hub 20a. The first bearing mount 342 can be formed on a first axial end of the hub 20a and can define a first circumferential bearing surface 390 and a first shoulder 392, while the second bearing mount 344 can be formed on a second, opposite axial end of the hub 20a and can define a second circumferential bearing surface 394 and a second shoulder 396.

[0033] First and second hub bearings 400 and 402, respectively, can be employed to support the hub 20a for rotation about the output axis 100 relative to the housing 12. In the example provided, the first and second hub bearings 400 and 402 are tapered roller bearings, but it will be appreciated that any appropriate type of bearing could be employed, such as angular contact bearings. The first hub bearing 400 can include a first inner bearing race 410, which is received on the first circumferential bearing surface 390 and can be abutted against the first shoulder 392, a first outer bearing race 412, which can be received into a first counterbore 414 formed on the first gearcase portion 60, and a plurality of first tapered rollers 416 that are received between the first inner bearing race 410 and the first outer bearing race 412. Similarly, the second hub bearing 402 can include a second inner bearing race 420 that can be received on the second circumferential bearing surface 394 and can abut the second shoulder 396, a second outer bearing race 422 which can be received into a second counterbore 424 that is formed in the second gearcase portion 62, and a plurality of second tapered rollers 426 that are received between the second inner bearing race 420 and the second outer bearing race 424. Optionally, the gear teeth 320 can extend radially outwardly from the hub 20a at a location along the output axis 100 that is between the first and second circumferential bearing surfaces 390 and 394. A rotary seal 450 can be disposed between the housing assembly 12 and the hub 20a. The rotary seal 450 can be received in a seal bore 452 in the second gearcase portion 62 and can sealingly engage a circumferentially extending seal surface 454 on the hub 20a.

[0034] 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 example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

CLAIMS What is claimed is:

1 . An electric drive unit comprising: a housing; a motor assembly coupled to the housing, the motor assembly having an electric motor with a motor output shaft that is rotatable about a motor axis; a transmission received in the housing, the transmission including an input pinion, an output gear and a pair of compound gears, the input pinion being coupled to the motor output shaft for rotation therewith, the output gear being rotatable about an output axis, each of the compound gears having a first intermediate gear, which is meshingly engaged with the input pinion, and a second intermediate gear that is meshingly engaged with the output gear and coupled to the first intermediate gear for rotation therewith; first and second hub bearings; and an output shaft; wherein the output gear has a hub and a gear portion, the hub defining an internally splined segment, a first bearing mount, and a second bearing mount, wherein the first bearing mount has a first circumferential bearing surface and a first shoulder, wherein the first hub bearing has a first inner bearing race that is received on the first circumferential bearing surface and abuts the first shoulder, wherein the second bearing mount has a second circumferential bearing surface and a second shoulder, wherein the second hub bearing has a second inner bearing race that is received on the second circumferential bearing surface and abuts the second shoulder, wherein the gear portion has a plurality of gear teeth and extends radially outwardly from the hub at a location along the output axis that is between the first and second circumferential bearing surfaces, wherein the internally splined segment being engaged with an externally splined segment on the output shaft to thereby rotatably couple the output shaft to the hub.

2. The electric drive unit of Claim 1 , wherein the hub defines a blind hole and wherein the internally splined segment has a plurality of spline teeth that are formed on a surface of the blind hole.

3. The electric drive unit of Claim 1, further comprising a rotary seal, the rotary seal being received in a seal bore in the housing and sealingly engaging a circumferentially extending seal surface on the hub of the output gear.

4. The electric drive unit of Claim 1 , wherein the first and second bearings are tapered roller bearings.

5. The electric drive unit of Claim 1, wherein the motor assembly includes an inverter.

6. The electric drive unit of Claim 5, wherein the inverter is disposed in the housing assembly.

7. The electric drive unit of Claim 1 , wherein a first ring groove is formed in the internally splined segment, wherein a second ring groove is formed in the externally splined segment, and wherein a retaining ring is disposed in the first and second ring grooves, the retaining ring resisting movement of the externally splined segment of the output shaft axially along the output axis relative to the hub.