A vehicle having a pair of electrically driven axles configured to operate in a tight turn mode

Abstract

A vehicle has 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 can operate in a highway mode in which the first, second, and third couplings are operated to allow power transmission from the motor to the differential, and the output shaft is driven by the differential. The electric drive axle can also operate in a tight turn mode in which the first, second, and third couplings prevent power transmission between the motor and the differential, preventing rotation of the differential, and are used to provide rotational power such that differential action by the differential drives one of the output shafts in a first rotational direction and rotates the other of the output shafts in a second (opposite) rotational direction.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This 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 herein. [Background technology]

[0002] [Technical field] The present disclosure relates to a vehicle having a pair of electric drive axles configured to operate in a tight turn mode. Summary of the Invention [Problem to be solved by the invention]

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

[0004] Vehicles manufactured by major equipment manufacturers that are configured to enable highway driving typically have one or two sets of vehicle wheels that can be steered via the vehicle's steering system. Typically, the input to the vehicle steering system is a steering wheel that is manually operated by the vehicle operator. However, with the advent of electronic steering, the input to the vehicle steering system can 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 enable the vehicle to turn through relatively shorter (i.e., smaller) radii than the radius through which the vehicle can be turned using the steering system alone. For example, the braking system of certain vehicles can operate to "lock" one wheel of the vehicle (i.e., the rear inner wheel) while providing rotational force to the other wheel of the vehicle, thereby causing the vehicle to turn around the "locked" wheel. Such a configuration significantly reduces the standard turning radius of the vehicle. Nevertheless, there is a need in the art for a vehicle configured to enable the vehicle to turn through even smaller radii, particularly without locking one of the wheels. [Means for solving the problem]

[0006] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its entire scope or every feature.

[0007] In one aspect, the present disclosure provides a vehicle including 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 within the housing and has a differential input member and a pair of differential output members. The differential input members are rotatable about an output shaft. Each of the first and second output shafts is coupled to a corresponding one of the differential input members and rotates 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 members. The second transmission output gear is rotatable about the shaft. The first coupling is selectively operable to couple the second output shaft to the second transmission output gear. The second coupling is selectively operable to interrupt torque transmission between the motor output shaft and the differential input member, and the third coupling is selectively operable to prevent rotation of the differential input member about the axis relative to the housing.

[0008] In another aspect, the present disclosure provides a method for operating a vehicle. The vehicle 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 within the housing and has a differential input member and a pair of differential output members. The differential input members are rotatable about an output shaft. Each of the first and second output shafts is coupled to a corresponding one of the differential input members and rotates 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 shaft. The method includes operating the motor assembly such that, when the first coupling disengages the second transmission output gear from the second output shaft, the second coupling operates to allow torque transmission between the motor output shaft and the differential input member and the third coupling operates to rotate the differential input member about the axis relative to the housing, thereby driving the first and second output shafts via the differential assembly; and operating the motor assembly such that, when the first coupling connects the second transmission output gear to the second output shaft, the second coupling operates to interrupt torque transmission between the motor output shaft and the differential input member and the third coupling operates to prevent rotation of the differential input member about the axis relative to the housing, thereby driving the first and second output shafts in opposite rotational directions. and operating the motor assembly when the first coupling couples the second transmission output gear to the second output shaft, the second coupling is actuated to interrupt torque transmission between the motor output shaft and the differential input member, and the third coupling operates to prevent rotation of the differential input member about said axis relative to the housing and 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. [Brief explanation of the drawings]

[0010] The drawings described herein are intended to illustrate only selected embodiments, not all possible embodiments, and are not intended to limit the scope of the present disclosure.

[0011] [Figure 1] FIG. 1 is a schematic diagram of an exemplary vehicle constructed in accordance with the teachings of the present disclosure.

[0012] [Figure 2] FIG. 2 is a schematic diagram of one of the drive axles of the vehicle of FIG. 1, the drive axle being shown in highway mode.

[0013] [Figure 3] FIG. 3 is a schematic diagram similar to FIG. 2 but showing the drive axle in tight turn mode.

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

[0015] 1, an exemplary vehicle 8 is shown including a pair of drive axles 10a, 10b used to drive two pairs of wheels 12a, 12b, respectively. Because the drive axles 10a, 10b are generally similar, only a description of drive axle 10b is provided here.

[0016] Referring to FIG. 2, the drive axle 10b may 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 may define a chamber 38 that may receive the differential assembly 24, the transmission 28, and one or more of the first, second, and third couplings 30, 32, and 34. The axle housing 20 is configured to be coupled to a body (not shown) of the vehicle 8 ( FIG. 1 ). If the drive axle 10 b is part of a dependent suspension, such as a beam axle, the axle housing 20 may be part of the unsprung mass of the vehicle 8. Alternatively, if the drive axle 10 b is part of an independent suspension, the axle housing 20 may be part of the spring mass of the vehicle 8.

[0018] The motor assembly 22 may include an electric motor 40 and an inverter 42. The electric motor 40 may be fixedly coupled to the axle housing 20 and may have a motor output shaft 44 rotatable about a motor axis. In the example provided, the electric motor 40 includes a motor housing 48 mounted directly to the exterior of the axle housing 20, with the motor output shaft 44 extending into a chamber 38 within the axle housing 20. Alternatively, the electric motor 40 may be mounted to the chamber 38 within the axle housing 20 (i.e., such that the electric motor 40 is substantially or entirely contained within the axle housing 20). The inverter 42 is electrically coupled to a source of DC power (i.e., a battery (not shown)) and configured to phase power to the windings of the electric motor 40 to drive the motor output shaft 44. In the example provided, the inverter 42 is attached to the electric motor 40.

[0019] The differential assembly 24 can include a differential input member 50 and first and second differential output members 52 a and 52 b, respectively. In the embodiment provided, the differential input member 50 is a differential carrier, and the first and second differential output members 52 a and 52 b are side gears that are part of a differential gear set 54 housed within the differential carrier. The differential carrier is supported by the axle housing 20 for rotation about the output shaft within the chamber 38. Each side gear is rotatable relative to the differential carrier about the output shaft. In addition to the side gears, the differential gear set 54 includes a cross pin 58, a pair of differential pinions 60, and a pair of side gears, which in the embodiment provided are the first and second differential output members 52 a and 52 b. The cross pin 58 is attached to the differential carrier and rotates with the differential carrier about the output shaft, extending perpendicular to the output shaft. Each of the differential pinions 60 is rotatably mounted on the cross pin 58 and is in meshing engagement with a respective side gear.

[0020] The first output shaft 26a is coupled to and rotates with the first differential output member 52a, and the second output shaft 26b is coupled to and rotates with the second differential output member 52b.

[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 reducer 68. The pinion 61, which is an input member of the transmission, is coupled to the motor output shaft 44 so as to rotate together with the motor output shaft 44 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 around the second output shaft 26b and is rotatable relative to the second output shaft 26b about the output axis. Optionally, a second intermediate reducer (not shown) may be employed between the pinion 61 and the first drive gear 62. The pinion 61 may drive the input of the second intermediate reducer, and the output of the second intermediate reducer may drive the first drive gear 62. The second drive gear 64 is rotatable about a first intermediate shaft that is parallel to and spaced from both the motor shaft and the output shaft. The output gear 66 is coupled to the differential input member 50 for common rotation about the output shaft. An intermediate reduction gear 68 is configured to transfer rotational power between the second drive gear 64 and the output gear 66. In the example provided, the intermediate reduction gear 68 includes a first intermediate gear 70 coupled to the second drive gear 64 for rotation about the first intermediate shaft, a second intermediate gear 72 meshingly engaged with the first intermediate gear 70, and a third intermediate gear 74 coupled to the second intermediate gear 72 for rotation therewith and female-sheathed engaged with the output gear 66. In the example provided, each gear of the transmission 28 is a helical gear, the second drive gear 64 and the 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 are parallel to and offset from the output shaft. 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 rotationally coupled to each other, and the second and third intermediate gears 72 and 74 are rotationally coupled to 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 shaft. While the first coupling can be any type of clutch (e.g., a dog clutch), in the provided embodiment, it includes a first sleeve rotatably 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 shaft between a first position (FIG. 2) in which the first sleeve is rotationally decoupled from 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 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 with a set of external teeth on the second output shaft 26b to rotationally and axially slidably couple the first sleeve to the second output shaft 26b, and a set of external teeth that are engageable with 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 provided embodiment, includes a second sleeve that is rotationally coupled 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 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 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 with a set of external teeth on the first shaft 80 so as to be rotationally and axially slidably coupled to the first shaft 80, and a set of external teeth that are engageable with 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 prevent rotation of the differential input member 50 relative to the axle housing 20. The third coupling 34 may be any type of device, such as a fixed member, such as a clutch (e.g., a dog clutch) or sleeve, operable in a first state ( FIG. 2 ) in which the third coupling 34 does not prevent rotation of the differential input member 50 relative to the axle housing 20, and a second state ( FIG. 3 ) in which the third coupling 34 prevents rotation of the differential input member 50 relative to the axle housing 20. In the example provided, the third coupling 34 includes a fixed member 120 coupled to the axle housing 20 and movable between a first position in which the fixed member 120 disengages the differential input member 50 and a second position in which the fixed member 120 engages the differential input member 50. However, it will be understood that the fixed member 120 need not have a configuration for engaging the differential input member 50. In this regard, the fixed member 120 may 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 another embodiment, stationary member 120 may include a gear segment (not shown) movable into meshing engagement with output gear 66, third intermediate gear 74, or second intermediate gear 72. When the gear segment is non-rotationally coupled to axle housing 20, engagement of the gear segment with one of output gear 66, third intermediate gear 74, second intermediate gear 72, or first intermediate gear 70 prevents rotation of differential input member 50. Alternatively, the gear segment may have a first portion that meshingly engages one of output gear 66, third intermediate gear 74, second intermediate gear 72, and first intermediate gear 70, and a second portion that meshingly engages another one of output gear 66, third intermediate gear 74, second intermediate gear 72, and first intermediate gear 70. In this alternative example, the gear segment is movable between a first position (the first and second portions are disengaged from the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70) and a second position (the first portion is engaged with 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 is engaged with teeth of another of the output gear 66, the third intermediate gear 74, the second intermediate gear 72 and the first intermediate gear 70).

[0026] 1 and 2, when the vehicle 8 is operated in highway mode, the electric motors 40 of the drive axles 10 a, 10 b are operated, the first coupling is operated in a mode in which the first drive gear 62 is rotationally decoupled from the second output shaft 26 b, the second coupling is operated in a mode in which each of the second drive gears 64 is rotationally coupled to a corresponding one of the first shafts 80, and the third coupling is operated in a mode in which the third coupler 34 does not prevent rotation of the differential input member 50 relative to the axle housing 20. Thus, rotational power generated by each electric motor 40 is not transmitted directly to the second output shaft 26 b of the drive axle, but rather is transmitted to the differential input member 50 via the second drive gear 64, the intermediate reduction gear 68, and the output gear 66, enabling the differential assembly 24 to drive both the first and second output shafts 26 a, 26 b.

[0027] When the vehicle 8 is operated in tight turn mode, the states of each of the first, second, and third couplings 30, 32, and 34 are switched (i.e., the first coupling 30 operates in a mode in which the first drive gear 62 is rotationally coupled to the second output shaft 26b, the second coupling 32 operates in a mode in which each of the second drive gears 64 is rotationally decoupled from the first shaft 80, and the third coupling 34 operates in a mode in which the third coupling 34 prevents rotation of the differential input member 50 relative to the axle housing 20). Operation of the vehicle 8 in this mode enables the electric motor 40 to drive the second output shaft 26b of each of the drive axles 10a, 10b in a first rotational direction (via the transmission of rotational power from the motor output shaft 44 to the pinion 61, the first drive gear 62, and the second output shaft 26b of each of the drive axles 10a, 10b). Rotation of the second output shaft 26b of each drive axle 10a, 10b provides a rotational input to the differential gear set 54, causing corresponding rotation of the first output shaft 26a in a second rotational direction opposite the first rotational direction. The differential gearing distributes the rotational power provided by the electric motor 40 between the first and second output shafts 26a, 26b, causing the first and second output shafts 26b to rotate in opposite rotational directions but at equal rotational speeds. As a result, each wheel of a pair of wheels 12a, 12b is driven in opposite rotational directions at equal rotational speeds. Assuming a sufficient level of traction between the ground and the wheels of each pair of wheels 12a, 12b, operation of the vehicle 8 in tight turn mode can be achieved by applying a coupling to each of the drive axles 10a, 10b about the longitudinal axis of the vehicle 8. Additionally, assuming the size of the coupling pair is large enough, the coupling can be used to assist in turning the vehicle 8 about a pivot axis around which the turning radius is significantly smaller than when turning the vehicle 8 via steering alone (i.e., using only the vehicle's steering wheel (not shown)), and about which the vehicle 8 can turn if the rear inner wheels are held non-rotating.

[0028] From the foregoing description, it will be understood that the transmission 28 includes a first transmission output gear (i.e., output gear 66) used to transmit rotational power to the differential input member 50 and a second transmission output gear (i.e., first drive gear 62) used to transmit rotational 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 present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, may be interchangeable and used in selected embodiments even if not specifically shown or described. The same can be varied in various ways. Such variations are not considered a departure from the present disclosure, and all such variations are intended to be included within the scope of the present disclosure.

Claims

1. A vehicle (8) comprising drive axles (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 is coupled to the housing (20) and has a motor output shaft (44); The differential assembly (24) is disposed in the housing (20) and has a differential input member (50) and a pair of differential output members (52a, 52b); The differential input member (50) is rotatable around an output shaft, each of the first and second output shafts (26a, 26b) is coupled to a corresponding one of the differential input members (52a, 52b) and thereby rotates with the corresponding one of the differential input members (52a, 52b); The transmission (28) has a transmission input gear (61), a first transmission output gear (66), and a second transmission output gear (62); the transmission input gear (61) is rotatably connected to the motor output shaft (44); The first transmission output gear (66) is connected to the differential input member (50), the second transmission output gear (62) is rotatable about the shaft; the first coupling (30) is selectively operable to connect the second output shaft (26b) to the second transmission output gear (62); the second coupling (32) is selectively operable to interrupt torque transmission between the motor output shaft (44) and the differential input member (50); The third coupling (34) is selectively operable to prevent rotation of the differential input member (50) about the axis relative to the housing (20).

2. 2. The vehicle (8) of claim 1, wherein the second transmission output gear (62) is in meshing engagement with the transmission input gear (61).

3. The transmission (28) includes a first shaft (80), a drive gear (64) meshing with the transmission input gear (61) and arranged concentrically around the first shaft (80), and a first intermediate gear (70) connected to the first shaft (80) for rotation therewith, the second coupling (32) selectively connecting the drive gear (64) to the first shaft (80); A vehicle (8) according to claim 1, characterized in that it is provided with 。

4. 4. The vehicle (8) according to claim 3, wherein the second coupling (32) is a dog clutch.

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

6. 6. The vehicle (8) of claim 5, wherein the sleeve has a set of internal teeth that engage with a set of external teeth formed on the first shaft (80) and a set of external teeth that can engage with a set of internal teeth formed on the drive gear (64).

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

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

9. 9. The vehicle (8) of claim 8, wherein the sleeve has a set of internal teeth that engage with a set of external teeth formed on the second output shaft (26b) and a set of external teeth that can engage with a set of internal teeth formed on the second transmission output gear (62).

10. 2. The vehicle (8) according to claim 1, wherein the third coupling (34) is a dog clutch.

11. 2. The vehicle (8) of claim 1, wherein the third coupling (34) includes a fixed member (120) movable between a first position in which the fixed member (120) is disengaged from the differential input member (50) and a second position in which the fixed member (120) is engaged with the differential input member (50).

12. A method of operating a vehicle (8), comprising: The vehicle (8) includes drive axles (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 is coupled to the housing (20) and has a motor output shaft (44); The differential assembly (24) is disposed within the housing (20) and includes a differential input member (50) and a pair of differential output members (52a, 52b); The differential input member (50) is rotatable around an output shaft, each of the first and second output shafts (26a, 26b) is coupled to a corresponding one of the differential input members (52a, 52b) for rotation therewith; The transmission (28) has a transmission input gear (61), a first transmission output gear (66), and a second transmission output gear (62); the transmission input gear (61) is rotatably coupled to the motor output shaft (44); The first transmission output gear (66) is connected to the differential input member (50), the second transmission output gear (62) is rotatable about the shaft; The method comprises: operating the motor assembly such that, when the first coupling (30) disengages the second transmission output gear (62) from the second output shaft (26b), the second coupling (32) operates to enable torque transmission between the motor output shaft (44) and the differential input member (50), and the third coupling (34) operates to rotate the differential input member (50) about the axis relative to the housing (20), thereby driving the first and second output shafts (26a, 26b) via the differential assembly (24); and and operating the motor assembly such that, when the first coupling (30) connects the second transmission output gear (62) to the second output shaft (26b), the second coupling (32) operates to interrupt torque transmission between the motor output shaft (44) and the differential input member (50) and the third coupling (34) operates to prevent rotation of the differential input member (50) about the axis relative to the housing (20), thereby driving the first and second output shafts (26a, 26b) in opposite rotational directions. A method for operating a vehicle (8).

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