Vehicle with a pair of electric drive axles that are configured to operate in a tight turn mode

Abstract

A vehicle with an electric drive axle having a motor, a differential, a pair of output shafts, a transmission, and first, second and third couplings. The electric drive axle is operable in a highway mode in which the first, second and third couplings are operated to permit power transmission from the motor to the differential so that the output shafts are driven by the differential. The electric drive axle is also operable in a tight-turn mode in which the first, second and third couplings are employed to inhibit power transmission between the motor and the differential, to inhibit rotation of the input of the differential and to provide rotary power to drive one of the output shafts in a first rotational direction so that differential action by the differential causes the other one of the output shaft to rotate in a second, opposite rotational direction.

Description

VEHICLE WITH A PAIR OF ELECTRIC DRIVE AXLES THAT ARE CONFIGURED TO OPERATE IN A TIGHT TURN MODECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 63 / 432,436 filed December 14, 2022, the disclosure of which is incorporated by reference as if fully set forth in detail herein.FIELD

[0002] The present disclosure relates to a vehicle having a pair of electric drive axles that are configured to operate in a tight turn mode.BACKGROUND

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

[0004] Vehicles manufactured by major original equipment manufacturers that are configured for operation on highways typically have one or two sets of vehicle wheels that can be steered via the vehicle steering system. Typically, the input for the vehicle steering system is a steering wheel that is manually operated by the operator of the vehicle. However, with the advent of electronic steering, the input for the vehicle steering system could additionally or alternatively be an electric motor that is controlled via software based on data from various sensors.

[0005] Some vehicles are further configured to permit the vehicle to be turned through a radius that is relatively tighter (i.e., smaller) than the radius through which the vehicle can be turned using the steering system alone. For example, the brake system of certain vehicles can be operated to "lock" one of the vehicle wheels (i.e., the rear inside wheel) while rotary power is provided to the other vehicle wheels to cause the vehicle to pivot about the "locked" vehicle wheel. Such configuration greatly reduces the standard turn radius of the vehicle. Nevertheless, there is a need in the art with a vehicle that is configuredso that the vehicle can be turned through a still smaller radius, particularly without locking one of the vehicle wheels.SUMMARY

[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 a vehicle that includes a drive axle having a housing, a motor assembly, a differential assembly, first and second output shafts, a transmission, a first coupling, a second coupling and a third coupling. The motor assembly is coupled to the housing and has a motor output shaft. The differential assembly is disposed in the housing and has a differential input member and a pair of differential output members. The differential input member is rotatable about an output axis. Each of the first and second output shafts is coupled to a corresponding one of the differential input members for rotation therewith. The transmission has a transmission input gear, a first transmission output gear and a second transmission output gear. The transmission input gear is rotatably coupled to the motor output shaft. The first transmission output gear is coupled to the differential input member. The second transmission output gear is rotatable about the axis. The first coupling is selectively operable for coupling the second output shaft to the second transmission output gear. The second coupling is selectively operable for interrupting torque transmission between the motor output shaft and the differential input member. The third coupling is selectively operable for inhibiting rotation of the differential input member about the axis relative to the housing.

[0008] In another form, the present disclosure provides a method for operating a vehicle. The vehicle includes a drive axle has a housing, a motor assembly, a differential assembly, first and second output shafts, a transmission, a first coupling, a second coupling and a third coupling. The motor assembly is coupled to the housing and has a motor output shaft. The differential assembly is disposed in the housing and has a differential input member and a pair of differential output members. The differential input member is rotatable about an output axis. Each of the first and second outputshafts is coupled to a corresponding one of the differential input members for rotation therewith. The transmission has a transmission input gear, a first transmission output gear and a second transmission output gear. The transmission input gear is rotatably coupled to the motor output shaft. The first transmission output gear is coupled to the differential input member. The second transmission output gear is rotatable about the axis. The method includes: operating the motor assembly when the first coupling decouples the second transmission output gear from the second output shaft, the second coupling is operated to permit torque transmission between the motor output shaft and the differential input member, and the third coupling is operated in a condition that permits rotation of the differential input member about the axis relative to the housing to drive the first and second output shafts through the differential assembly; and operating the motor assembly when the first coupling couples the second transmission output gear to the second output shaft, the second coupling is operated to inhibit torque transmission between the motor output shaft and the differential input member, and the third coupling is operated in a condition that inhibits rotation of the differential input member about the axis relative to the housing to drive the first and second output shafts in opposite rotational directions.

[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 schematic illustration of an exemplary vehicle constructed in accordance with the teachings of the present disclosure;

[0012] Figure 2 is a schematic illustration of one of the drive axles of the vehicle of Figure 1 , the drive axle being shown in a highway mode; and

[0013] Figure 3 is a schematic illustration similar to that of Figure 2 but depicting the drive axle in a tight turn mode.

[0014] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.DETAILED DESCRIPTION

[0015] With reference to Figure 1 , an exemplary vehicle 8 is illustrated to include a pair of drive axles 10a, 10b that are employed to drive two pair of vehicle wheels 12a, 12b, respectively. As the drive axles 10a, 10b are generally similar, only a discussion of drive axle 10b will be provided herein.

[0016] With reference to Figure 2, the drive axle 10b can include an axle housing 20, a motor assembly 22, a differential assembly 24, first and second output shafts 26a and 26b, respectively, a transmission 28, a first coupling 30, a second coupling 32 and a third coupling 34.

[0017] The axle housing 20 can define a chamber 38 into which the differential assembly 24, the transmission 28, and one or more of the first, second and third couplings 30, 32 and 34 can be received. The axle housing 20 is configured to be coupled to a body (not shown) of the vehicle 8 (Fig. 1 ). The axle housing 20 can be part of the unsprung mass of the vehicle 8 if the drive axle 10b is part of a dependent suspension, such as a beam axle for example. Alternatively, the axle housing 20 can be a part of the sprung mass of the vehicle 8 if the drive axle 10b is part of an independent suspension.

[0018] The motor assembly 22 can include an electric motor 40 and an inverter 42. The electric motor 40 can be fixedly coupled to the axle housing 20 and can have a motor output shaft 44 that is rotatable about a motor axis. In the example provided, the electric motor 40 includes a motor housing 48 that is directly mounted to an exterior surface of the axle housing 20 and the motor output shaft 44 extends into the chamber 38 in the axle housing 20. Alternatively, the electric motor 40 could be mounted in the chamber 38 in the axle housing 20 (i.e., so that the electric motor 40 is contained substantially or wholly within the axle housing 20). The inverter 42 is configured to be electrically coupled to a source of direct current electrical power (i.e., a battery - not shown) and to phase electrical power to the windings of the electric motor40 to drive the motor output shaft 44. In the example provided, the inverter 42 is mounted to the electric motor 40.

[0019] The differential assembly 24 can include a differential input member 50 and first and second differential output members 52a and 52b, respectively. In the example provided, the differential input member 50 is a differential carrier and the first and second differential output members 52a and 52b are side gears that are part of a differential gearset 54 that is received within the differential carrier. The differential carrier is supported by the axle housing 20 for rotation in the chamber 38 about an output axis. Each of the side gears is rotatable relative to the differential carrier about the output axis. In addition to the side gears, the differential gearset 54 includes a cross-pin 58, a pair of differential pinions 60, and a pair of side gears, which are the first and second differential output members 52a and 52b in the example provided. The cross-pin 58 is mounted to the differential carrier for rotation therewith about the output axis and extends perpendicular to the output axis. Each of the differential pinions 60 is rotatably mounted on the cross-pin 58 and meshingly engages each of the side gears.

[0020] The first output shaft 26a is coupled to the first differential output member 52a for rotation therewith, while the second output shaft 26b is coupled to the second differential output member 52b for rotation therewith.

[0021] The transmission 28 includes a pinion 61 , a first drive gear 62, a second drive gear 64, an output gear 66 and an intermediate reduction 68. The pinion 61 , which is an input member (i.e., a transmission input member) of the transmission, is coupled to the motor output shaft 44 for rotation therewith about the motor axis. The pinion 61 is meshingly engaged with both the first drive gear 62 and the second drive gear 64. The first drive gear 62 is disposed about the second output shaft 26b and is rotatable relative to the second output shaft 26b about the output axis. Optionally, a second intermediate reduction (not shown) could be employed between the pinion 61 and the first drive gear 62. The pinion 61 could drive an input of the second intermediate reduction and an output of the second intermediate reduction could drive the first drive gear 62. The second drive gear 64 is rotatable about a first intermediate axis that is parallel to and spaced apart from both the motor axis and the output axis. Theoutput gear 66 is coupled to the differential input member 50 for common rotation about the output axis. The intermediate reduction 68 is configured to transmit rotary power between the second drive gear 64 and the output gear 66. In the example provided, the intermediate reduction 68 includes a first intermediate gear 70, which is coupled to the second drive gear 64 for rotation therewith about the first intermediate axis, a second intermediate gear 72, which is meshingly engaged to the first intermediate gear 70, and a third intermediate gear 74, which is coupled to the second intermediate gear 72 for rotation therewith and meshingly engaged to the output gear 66. In the example provided, each of the gears of the transmission 28 is a helical gear, the second drive gear 64 and first intermediate gear 70 are mounted on a first shaft 80, the second and third intermediate gears 72 and 74 are mounted on a second shaft 82 and each of the first and second shafts 80 and 82 is parallel to and offset from the output axis. In the example provided, the second drive gear 64 is rotatable relative to the first shaft 80, the first intermediate gear 70 and the first shaft are coupled for rotation with one another, and the second and third intermediate gears 72 and 74 are coupled for rotation with the second shaft 82.

[0022] The first coupling 30 is configured to selectively couple the first drive gear 62 to the second output shaft 26b for common rotation about the output axis. The first coupling can be any type of clutch (e.g., a dog clutch), but in the example provided, comprises a first sleeve that is rotationally and axially slidably coupled to one of the first drive gear 62 and the second output shaft 26b. The first sleeve is movable along the output axis between a first position (Fig. 2), in which the first sleeve is rotationally decoupled from the other one of the first drive gear 62 and the second output shaft 26b, and a second position (Fig. 3) in which the first sleeve is rotationally coupled to the other one of the first drive gear 62 and the second output shaft 26b. In the example provided, the first sleeve has a set of internal teeth that engage a set of external teeth on the second output shaft 26b to rotationally and axially slidably couple first sleeve to the second output shaft 26b, and a set of external teeth that are engagable to a set of internal teeth formed on the first drive gear 62 when the first sleeve is in the second position.

[0023] The second coupling 32 is configured to selectively couple the second drive gear 64 to the first shaft 80 for common rotation about the first intermediate axis. The second coupling 32 can be any type of clutch (e.g., a dog clutch), but in the example provided comprises a second sleeve that is rotationally and axially slidably coupled to one of the second drive gear 64 and the first shaft 80. The second sleeve is movable along the first intermediate axis between a first position (Fig. 2), in which the second sleeve is rotationally decoupled from the other one of the second drive gear 64 and the first shaft 80, and a second position (Fig. 3) in which the second sleeve is rotationally coupled to the other one of the second drive gear 64 and the first shaft 80. In the example provided, the second sleeve has a set of internal teeth that engage a set of external teeth on the first shaft 80 to rotationally and axially slidably couple second sleeve to the first shaft 80, and a set of external teeth that are engagable to a set of internal teeth formed on the second drive gear 64 when the second sleeve is in the second position.

[0024] The third coupling 34 is configured to selectively inhibit rotation of the differential input member 50 relative to the axle housing 20. The third coupling 34 can be any type of device, such as a clutch (e.g., dog clutch), or an immobilization member, such as a sleeve, that can be operated in a first condition (Fig. 2), where the third coupling 34 does not inhibit rotation of the differential input member 50 relative to the axle housing 20, and a second condition (Fig. 3) in which the third coupling 34 inhibits rotation of the differential input member 50 relative to the axle housing 20. In the example provided, the third coupling 34 comprises an immobilization member 120 that is coupled to the axle housing 20 and is movable between a first position, in which the immobilization member 120 clears the differential input member 50, and a second position in which the immobilization member 120 engages the differential input member 50. It will be appreciated, however, that the immobilization member 120 need not have a configuration that engages the differential input member 50. In this regard, the immobilization member 120 could be configured to engage one or more of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 , the second shaft 82 and the first shaft 80.

[0025] In one alternative example, the immobilization member 120 could comprise a gear segment (not shown) that is movable into a position that meshingly engages the output gear 66, the third intermediate gear 74 or the second intermediate gear 72. If the gear segment is non-rotatably coupled to the axle housing 20, the engagement of the gear segment with one of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 or the first intermediate gear 70 will inhibit rotation of the differential input member 50. Alternatively, the gear segment could have a first portion, which can meshingly engage one of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70, and a second portion that can meshingly engage another one of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70. In this alternate example, the gear segment is movable between a first position, in which the first and second portions clear the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70, and a second position in which the first portion engages the teeth of one of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70 and the second portion engages the teeth on a different one of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70.

[0026] With reference to Figures 1 and 2, when the vehicle 8 is operated in a highway mode, the electric motors 40 of the drive axles 10a, 10b are operated, the first couplings 30 are operated in a mode where the first drive gears 62 are rotationally decoupled from the second output shafts 26b, the second couplings 32 are operated in a mode where each of the second drive gears 64 is rotationally coupled to a corresponding one of the first shafts 80, and the third couplings 34 are operated in a mode where the third couplings 34 do not inhibit rotation of the differential input members 50 relative to the axle housings 20. Accordingly rotary power produced by each electric motor 40 is not transmitted directly to the second output shaft 26b of the drive axle, but rather through the second drive gear 64, the intermediate reduction 68, the output gear 66 and into the differential input member 50, permitting thedifferential assembly 24 to drive both the first and second output shafts 26a and 26b.

[0027] When the vehicle 8 is operated in a tight turn mode, the condition of each of the first, second and third couplings 30, 32 and 34 is switched (i.e., the first couplings 30 are operated in a mode where the first drive gears 62 are rotationally coupled to the second output shafts 26b, the second couplings 32 are operated in a mode where each of the second drive gears 64 is rotationally decoupled from the first shafts 80, and the third couplings 34 are operated in a mode where the third couplings 34 inhibit rotation of the differential input members 50 relative to the axle housings 20). Operation of the vehicle 8 in this mode permits the electric motors 40 to drive the second output shafts 26b of the drive axles 10a, 10b in a first rotational direction (through the transmission of rotary power from the motor output shaft 44, to the pinion 61 , the first drive gear 62 and to the second output shaft 26b of each of the drive axles 10a, 10b). Rotation of the second output shaft 26b of each of the drive axles 10a, 10b provides a rotary input to the differential gearset 54, causing corresponding rotation of the first output shaft 26a in a second rotational direction that is opposite the first rotational direction. The differential gearing (i.e., - permits the rotary power that is provided by the electric motor 40 to be distributed between the first and second output shafts 26a and 26b such that the first and second output shafts 26b rotate in opposite rotational directions but with equal rotational speed. Consequently, each wheel in a pair of the vehicle wheels 12a, 12b is driven in opposite rotational directions with equal rotational speed. Assuming a sufficient level of traction between the ground and the wheels of each pair of vehicle wheels 12a, 12b, operation of the vehicle 8 in the tight turn mode can apply a couple to each of the drive axles 10a, 10b that is centered about the longitudinal axis of the vehicle 8. Assuming also that the magnitude of the pair of couples is sufficiently large, the couples can be employed to aid in turning the vehicle 8 about a pivot axis where a radius of the turn is significantly smaller than that by which the vehicle 8 can be turned through steering alone (i.e., solely through the use of the vehicle steering wheel (not shown)) and that by which the vehicle 8 can be turned if the rear inside wheel were held in a non-rotating condition.

[0028] From the foregoing discussion, it will be appreciated that the transmission 28 includes a first transmission output gear (i.e., the output gear 66), which is employed to transmit rotary power to the differential input member 50, and a second transmission output gear (i.e., the first drive gear 62) that is employed to transmit rotary power to the second output shaft 26b.

[0029] 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, 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

CLAIMSWhat is claimed is:1 . A vehicle (8) comprising: a drive axle (10a, 10b) having a housing (20), a motor assembly (22), a differential assembly (24), first and second output shafts (26a, 26b), a transmission (28), a first coupling (30), a second coupling (32) and a third coupling (34), the motor assembly being coupled to the housing (20) and having a motor output shaft (44), the differential assembly (24) being disposed in the housing (20) and having a differential input member (50) and a pair of differential output members (52a, 52b), the differential input member (50) being rotatable about an output axis, each of the first and second output shafts (26a, 26b) being coupled to a corresponding one of the differential input members (52a, 52b) for rotation therewith, the transmission (28) having a transmission input gear (61), a first transmission output gear (66) and a second transmission output gear (62), the transmission input gear (61 ) being rotatably coupled to the motor output shaft (44), the first transmission output gear (66) being coupled to the differential input member (50), the second transmission output gear (62) being rotatable about the axis, the first coupling (30) being selectively operable for coupling the second output shaft (26b) to the second transmission output gear (62), the second coupling (32) being selectively operable for interrupting torque transmission between the motor output shaft (44) and the differential input member (50), the third coupling (34) being selectively operable for inhibiting rotation of the differential input member (50) about the axis relative to the housing (20).

2. The vehicle (8) of Claim 1 , wherein the second transmission output gear (62) is meshingly engaged to the transmission input gear (61 ).

3. The vehicle (8) of Claim 1 , wherein the transmission (28) includes a first shaft (80), a drive gear (64), which is meshingly engaged to the transmission input gear (61 ) and concentrically disposed about the first shaft (80), and a first intermediate gear (70) that is coupled to the first shaft (80) forrotation therewith and wherein the second coupling (32) selectively couples the drive gear (64) to the first shaft (80).

4. The vehicle (8) of Claim 3, wherein the second coupling (32) is a dog clutch.

5. The vehicle (8) of Claim 3, wherein the second coupling (32) comprises a sleeve that is rotationally and axially slidably coupled to one of the drive gear (64) and the first shaft (80).

6. The vehicle (8) of Claim 5, wherein the sleeve has a set of internal teeth, which are engaged to a set of external teeth formed on the first shaft (80), and a set of external teeth that are engagable to a set of internal teeth formed on the drive gear (64).

7. The vehicle (8) of Claim 1 , wherein the first coupling (30) is a dog clutch.

8. The vehicle (8) of Claim 1 , wherein the first coupling (30) comprises a sleeve that is rotationally and axially slidably coupled to one of the second output shaft (26b) and the second transmission output gear (62).

9. The vehicle (8) of Claim 8, wherein the sleeve has a set of internal teeth, which are engaged to a set of external teeth formed on the second output shaft (26b), and a set of external teeth that are engagable to a set of internal teeth formed on the second transmission output gear (62).

10. The vehicle (8) of Claim 1 , wherein the third coupling (34) is a dog clutch.

11. The vehicle (8) of Claim 1 , wherein the third coupling (34) comprises an immobilization member (120) that is movable between a first position, in which the immobilization member (120) clears the differential inputmember (50), and a second position in which the immobilization member (120) is engaged to the differential input member (50).

12. A method for operating a vehicle (8), the vehicle having a drive axle (10a, 10b) having a housing (20), a motor assembly (22), a differential assembly (24), first and second output shafts (26a, 26b), a transmission (28), a first coupling (30), a second coupling (32) and a third coupling (34), the motor assembly being coupled to the housing (20) and having a motor output shaft (44), the differential assembly (24) being disposed in the housing (20) and having a differential input member (50) and a pair of differential output members (52a, 52b), the differential input member (50) being rotatable about an output axis, each of the first and second output shafts (26a, 26b) being coupled to a corresponding one of the differential input members (52a, 52b) for rotation therewith, the transmission (28) having a transmission input gear (61), a first transmission output gear (66) and a second transmission output gear (62), the transmission input gear (61 ) being rotatably coupled to the motor output shaft (44), the first transmission output gear (66) being coupled to the differential input member (50), the second transmission output gear (62) being rotatable about the axis, the method comprising: operating the motor assembly when the first coupling (30) decouples the second transmission output gear (62) from the second output shaft (26b), the second coupling (32) is operated to permit torque transmission between the motor output shaft (44) and the differential input member (50), and the third coupling (34) is operated in a condition that permits rotation of the differential input member (50) about the axis relative to the housing (20) to drive the first and second output shafts (26a, 26b) through the differential assembly (24); and operating the motor assembly when the first coupling (30) couples the second transmission output gear (62) to the second output shaft (26b), the second coupling (32) is operated to inhibit torque transmission between the motor output shaft (44) and the differential input member (50), and the third coupling (34) is operated in a condition that inhibits rotation of the differential input member (50) about the axis relative to the housing (20) to drive the first and second output shafts (26a, 26b) in opposite rotational directions.

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