Vehicle having pair of electrically driven axles configured to operate in compact turn mode

Abstract

A vehicle with an electrically driven axle having a motor, a differential, a pair of output shafts, a transmission, and first, second, and third couplings. The electrically driven axle may be operated in a high speed mode in which the first coupling, the second coupling, and the third coupling are operated to allow power transfer from the horse to the differential such that the output shaft is driven by the differential. The electrically driven axle is also operable in a compact turn mode in which the first, second, and third couplings are used to impede power transfer between the motor and the differential to impede rotation of the input of the differential and to provide rotational power to drive one of the output shafts in a first rotational direction and to impede rotation of the input of the differential in a second rotational direction. Such that the differential action of the differential causes the other one of the output shafts to rotate in an opposite second rotational direction.

Description

Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application 63 / 432,436, filed on Dec. 14, 2022, the disclosure of which is incorporated herein by reference in its entirety as if set forth in detail. Technical Field

[0002] The present disclosure relates to a vehicle having a pair of electric drive axles configured to operate in a compact turn mode. Background Art

[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 and configured to operate on highways typically have one or two sets of vehicle wheels that can be steered via a vehicle steering system. Generally, the input to the vehicle steering system is a steering wheel manually operated by an operator of the vehicle. However, with the advent of electric 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 allow the vehicle to turn through a radius that is relatively more compact (i.e., smaller) than the radius through which the vehicle can turn using only the steering system. For example, the braking system of some vehicles can be operated to “lock” one vehicle wheel (i.e., the rear inner wheel) while providing rotational power to the other vehicle wheels to pivot the vehicle around the “locked” vehicle wheel. This configuration significantly reduces the standard turning radius of the vehicle. Nevertheless, there is still a need in the art for a vehicle that is configured such that the vehicle can turn through a smaller radius, particularly without locking one vehicle wheel. Summary of the Invention

[0006] This section provides a general overview of the present disclosure and is not an exhaustive disclosure of all aspects of the present disclosure or all features of the present disclosure.

[0007] In one form, the present disclosure provides a vehicle that includes a drive axle, The drive axle has a housing, a motor assembly, a differential assembly, a first output shaft and a second output shaft, a transmission, a first coupler, a second coupler and a third coupler. 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 output shaft and the second output shaft is coupled to a respective one of the differential input members to rotate with the differential input member. 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 coupler is selectively operable to couple the second output shaft to the second transmission output gear. The second coupler is selectively operable to interrupt torque transmission between the motor output shaft and the differential input member. The third coupler is selectively operable to impede rotation of the differential input member relative to the housing about the axis.

[0008] In another form, the present disclosure provides a method of operating a vehicle. The vehicle includes a drive axle having a housing, a motor assembly, a differential assembly, a first output shaft and a second output shaft, a transmission, a first coupler, a second coupler and a third coupler. 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 output shaft and the second output shaft is coupled to a respective one of the differential input members to rotate with the differential input member. 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 to drive the first output shaft and the second output shaft through the differential assembly when: the first coupler disengages the second transmission output gear from the second output shaft; the second coupler is operated to allow torque transmission between the motor output shaft and the differential input member; and the third coupler is operated in a state that allows the differential input member to rotate relative to the housing about the axis; and operating the motor assembly to drive the first output shaft and the second output shaft in an opposite rotational direction when: the first coupler couples the second transmission output gear to the second output shaft; the second coupler is operated to impede torque transmission between the motor output shaft and the differential input member; and the third coupler is operated in a state that impedes rotation of the differential input member relative to the housing about the axis.

[0009] Additional applicable scopes can be clearly seen from the description provided herein. The description and specific examples in the present disclosure are for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE 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 Figure 1 a schematic illustration of one of the drive axles of the vehicle, with the drive axle shown in a high-speed mode; and

[0013] Figure 3 is similar to Figure 2 but depicts the drive axle in a tight-turning mode.

[0014] In the various views of the drawings, corresponding reference numerals represent corresponding components. DETAILED DESCRIPTION

[0015] Referring to Figure 1 , the exemplary vehicle 8 is shown as including a pair of drive axles 10a, 10b, which are respectively used to drive two pairs of vehicle wheels 12a, 12b. Since the drive axles 10a, 10b are generally similar, only the drive axle 10b will be discussed herein.

[0016] Referring to Figure 2 , the drive axle 10b may include an axle housing 20, a motor assembly 22, a differential assembly 24, respectively including a first output shaft 26a and a second output shaft 26b, including a transmission 28, a first coupler 30, a second coupler 32, and a third coupler 34.

[0017] The axle housing 20 may define a chamber 38, and one or more of the differential assembly 24, the transmission 28, and the first coupler 30, the second coupler 32, and the third coupler 34 may be received in the chamber. The axle housing 20 is configured to be coupled to the body (not shown) of the vehicle 8 ( Figure 1 ). If the drive axle 10b is part of a non-independent 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 10b is part of an independent suspension, the axle housing 20 may be part of the sprung mass of the vehicle 8.

[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 can rotate about a motor axis. In the provided example, the electric motor 40 includes a motor housing 48 that is directly mounted to the outer surface of the axle housing 20, and the motor output shaft 44 extends into a chamber 38 within the axle housing 20. Alternatively, the electric motor 40 can be mounted within the chamber 38 of 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 configured to be electrically coupled to a DC power source (i.e., a battery - not shown) and deliver a phase - modulated power to the windings of the electric motor 40 to drive the motor output shaft 44. In the provided example, the inverter 42 is mounted to the electric motor 40.

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

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

[0021] The transmission 28 includes a pinion gear 61, a first drive gear 62, a second drive gear 64, an output gear 66, and an intermediate reduction gear 68. The pinion gear 61, which is an input member of the transmission (i.e., the transmission input member), is coupled to the motor output shaft 44 and configured to rotate about the motor axis together with the motor output shaft. The pinion gear 61 is meshingly engaged with 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 about the output axis relative to the second output shaft 26b. Optionally, a second intermediate reduction gear (not shown) may be used between the pinion gear 61 and the first drive gear 62. The pinion gear 61 may drive an input end of the second intermediate reduction gear, and an output end of the second intermediate reduction gear may drive the first drive gear 62. The second drive gear 64 is rotatable about a first intermediate axis that is parallel to and spaced from the motor axis and the output axis. The output gear 66 is coupled to the differential input member 50 to rotate about the output axis together. The intermediate reduction gear 68 is configured to transfer rotational power between the second drive gear 64 and the output gear 66. In the provided example, the intermediate reduction gear 68 includes: a first intermediate gear 70 that is coupled to the second drive gear 64 and configured to rotate about the first intermediate axis together with the second drive gear; a second intermediate gear 72 that is meshingly engaged with the first intermediate gear 70; and a third intermediate gear 74 that is coupled to the second intermediate gear 72 and configured to rotate together with the second intermediate gear, and the third intermediate gear is meshingly engaged with the output gear 66. In the provided example, each of the gears in 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 intermediate gear 72 and the third intermediate gear 74 are mounted on a second shaft 82, and each of the first shaft 80 and the second shaft 82 is parallel to and offset from the output axis. In the provided example, the second drive gear 64 is rotatable relative to the first shaft 80, the first intermediate gear 70 and the first shaft are coupled to each other for rotation, and the second intermediate gear 72 and the third intermediate gear 74 are coupled to the second shaft 82 for rotation.

[0022] The first coupler 30 is configured to selectively couple the first drive gear 62 to the second output shaft 26b to rotate about the output axis together. The first coupler may be any type of clutch (e.g., a toothed clutch), but in the provided example, the first coupler includes a first bushing that is rotatably and axially slidably coupled to one of the first drive gear 62 and the second output shaft 26b. The first bushing may be in a first position along the output axis ( Figure 2 ) and a second position ( Figure 3) moves between them. In the first position, the first bushing is rotationally disengaged from the other of the first drive gear 62 and the second output shaft 26b. In the second position, the first bushing is rotationally coupled to the other of the first drive gear 62 and the second output shaft 26b. In the provided example, the first bushing 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 the first bushing to the second output shaft 26b, and the first bushing has a set of external teeth that can engage a set of internal teeth formed on the first drive gear 62 when the first bushing is in the second position.

[0023] The second coupler 32 is configured to selectively couple the second drive gear 64 to the first shaft 80 to rotate together about the first intermediate axis. The second coupler 32 can be any type of clutch (e.g., a toothed clutch), but in the provided example, the second coupler includes a second bushing that is rotationally and axially slidably coupled to one of the second drive gear 64 and the first shaft 80. The second bushing can move along the first intermediate axis between a first position ( Figure 2 ) and a second position ( Figure 3 ) between them. In the first position, the second bushing is rotationally disengaged from the other of the second drive gear 64 and the first shaft 80. In the second position, the second bushing is rotationally coupled to the other of the second drive gear 64 and the first shaft 80. In the provided example, the second bushing has a set of internal teeth that engage a set of external teeth on the first shaft 80 to rotationally and axially slidably couple the second bushing to the first shaft 80, and the second bushing has a set of external teeth that can engage a set of internal teeth formed on the second drive gear 64 when the second bushing is in the second position.

[0024] The third coupler 34 is configured to selectively impede the rotation of the differential input member 50 relative to the axle housing 20. The third coupler 34 can be any type of device, such as a clutch (e.g., a toothed clutch), or a fixed member, such as a bushing, that can be in a first state ( Figure 2 ) and a second state ( Figure 3)In the following operation, in the first state, the third coupler 34 does not impede the rotation of the differential input member 50 relative to the axle housing 20, and in the second state, the third coupler 34 impedes the rotation of the differential input member 50 relative to the axle housing 20. In the provided example, the third coupler 34 includes a fixed member 120 that is coupled to the axle housing 20 and is movable between a first position and a second position. In the first position, the fixed member 120 is away from the differential input member 50, and in the second position, the fixed member 120 engages with the differential input member 50. However, it can be understood that the fixed member 120 is not necessarily configured to engage with the differential input member 50. In this regard, the fixed member 120 can be configured to engage with one or more of the output gear 66, the third idler gear 74, the second idler gear 72, the second shaft 82, and the first shaft 80.

[0025] In an alternative example, the fixed member 120 can include a gear segment (not shown), which can be moved to a position where it meshingly engages with the output gear 66, the third idler gear 74, or the second idler gear 72. If the gear segment is non-rotatably coupled to the axle housing 20, the engagement of the gear segment with the output gear 66, the third idler gear 74, the second idler gear 72, or the first idler gear 70 will impede the rotation of the differential input member 50. Alternatively, the gear segment can have a first portion and a second portion. The first portion can meshingly engage with one of the output gear 66, the third idler gear 74, the second idler gear 72, and the first idler gear 70, and the second portion can meshingly engage with another one of the output gear 66, the third idler gear 74, the second idler gear 72, and the first idler gear 70. In this alternative example, the gear segment is movable between a first position and a second position. In the first position, the first portion and the second portion are away from the output gear 66, the third idler gear 74, the second idler gear 72, and the first idler gear 70. In the second position, the first portion engages with the teeth of one of the output gear 66, the third idler gear 74, the second idler gear 72, and the first idler gear 70, and the second portion engages with the teeth on a different one of the output gear 66, the third idler gear 74, the second idler gear 72, and the first idler gear 70.

[0026] Referring to Figure 1 and Figure 2 , when the vehicle 8 is operating in the high-speed mode, the electric motors 40 driving the axle assemblies 10a, 10b are operated, the first coupler 30 is operated in a mode where the first drive gear 62 is rotationally disengaged from the second output shaft 26b; the second coupler 32 is operated in a mode where each of the second drive gears 64 is rotationally coupled to a respective one of the first shafts 80; and The third coupler 34 is operated in a mode where it does not impede the rotation of the differential input member 50 relative to the axle housing 20. Thus, the rotational power generated by each electric motor 40 is not directly transmitted to the second output shaft 26b of the drive axle, but rather passes through the second drive gear 64, the intermediate reduction gear 68, the output gear 66 and reaches the differential input member 50, thereby allowing the differential assembly 24 to drive both the first output shaft 26a and the second output shaft 26b.

[0027] When the vehicle 8 is operated in a tight turning mode, the state of each of the first coupler 30, the second coupler 32 and the third coupler 34 is switched (i.e., the first coupler 30 is operated in a mode where the first drive gear 62 is rotationally coupled to the second output shaft 26b, the second coupler 32 is operated in a mode where each of the second drive gears 64 is rotationally disengaged from the first shaft 80, and the third coupler 34 is operated in a mode where it impedes the rotation of the differential input member 50 relative to the axle housing 20). The operation of the vehicle 8 in this mode allows the electric motor 40 to drive the second output shaft 26b of the drive axles 10a, 10b in the first rotational direction (by transmitting the rotational 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). The rotation of the second output shaft 26b of each of the drive axles 10a, 10b provides a rotational input to the differential gear set 54, causing the first output shaft 26a to rotate in a second rotational direction opposite to the first rotational direction. The differential gear arrangement allows the rotational power provided by the electric motor 40 to be distributed between the first output shaft 26a and the second output shaft 26b such that the first output shaft and the second output shaft 26b rotate in opposite rotational directions but at equal rotational speeds. Thus, each of a pair of vehicle wheels 12a, 12b is driven at equal rotational speeds in opposite rotational directions. Assuming there is sufficient horizontal friction between the ground and the wheels of each pair of vehicle wheels 12a, 12b, the operation of the vehicle 8 in the tight turning mode can apply a couple centered on the longitudinal axis of the vehicle 8 to each of the drive axles 10a, 10b. Additionally, assuming the magnitude of this couple is large enough, this couple can be used to assist the vehicle 8 in turning about a pivot axis, where the radius of this turn is significantly less than the radius of a turn of the vehicle 8 by steering alone (i.e., by using only the vehicle steering wheel (not shown)), and less than the radius of a turn of the vehicle 8 with the rear inner wheel held in a non-rotating state.

[0028] In view of the foregoing discussion, it will be appreciated that the transmission 28 includes a first transmission output gear (i.e., output gear 66) and a second transmission output gear (i.e., first drive gear 62), the first transmission output gear being configured to transmit rotational power to the differential input member 50 and the second transmission output gear being configured 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 disclosure. The 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 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

1. A vehicle (8) comprising: Drive axles (10a, 10b) having a housing (20), a motor assembly (22), a differential assembly (24), a first output shaft (26a) and a second output shaft (26b), a transmission (28), a first coupling (30), a second coupling (32) and a third coupling (34), the motor assembly (22) 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 output shaft (26a) and the second output shaft (26b) being coupled to a respective one of the differential input members (52a, 52b) to rotate 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 to couple the second output shaft (26b) to the second transmission output gear (62), the second coupling (32) being selectively operable to interrupt torque transmission between the motor output shaft (44) and the differential input member (50), and the third coupling (34) being selectively operable to impede rotation of the differential input member (50) relative to the housing (20) about the axis.

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

3. The vehicle (8) according to claim 1, wherein, The transmission (28) includes a first shaft (80), a drive gear (64) and a first intermediate gear (70), the drive gear being meshingly engaged with the transmission input gear (61) and being concentrically disposed about the first shaft (80), the first intermediate gear being coupled to the first shaft (80) to rotate therewith, and wherein the second coupling (32) selectively couples the drive gear (64) to the first shaft (80).

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

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

6. The vehicle (8) according to claim 5, wherein, The sleeve has a set of internal teeth engaging a set of external teeth formed on the first shaft (80), and the sleeve has a set of external teeth capable of engaging a set of internal teeth formed on the drive gear (64).

7. The vehicle (8) according to claim 1, wherein, The first coupling (30) is a toothed clutch.

8. The vehicle (8) according to claim 1, wherein, The first coupler (30) includes a sleeve that is rotatably and axially slidably coupled to one of the second output shaft (26b) and the second transmission output gear (62).

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

10. The vehicle (8) according to claim 1, wherein, The third coupler (34) is a toothed clutch.

11. The vehicle (8) according to claim 1, wherein, The third coupler (34) includes a fixed member (120) that is 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) engages the differential input member (50).

12. A method for operating a vehicle (8) having drive axles (10a, 10b) with a housing (20), a motor assembly (22), a differential assembly (24), a first output shaft (26a) and a second output shaft (26b), a transmission (28), a first coupler (30), a second coupler (32) and a third coupler (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 output shaft (26a) and the second output shaft (26b) being coupled to a respective one of the differential output members (52a, 52b) to rotate 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 to drive the first output shaft (26a) and the second output shaft (26b) through the differential assembly (24) when: the first coupler (30) disengages the second transmission output gear (62) from the second output shaft (26b); the second coupler (32) is operated to permit torque transfer between the motor output shaft (44) and the differential input member (50); and the third coupler (34) is operated in a state that permits the differential input member (50) to rotate about the axis relative to the housing (20); and The motor assembly is operated in the following circumstances to drive the first output shaft (26a) and the second output shaft (26b) in opposite rotational directions, namely: the first coupling (30) couples the second transmission output gear (62) to the second output shaft (26b); the second coupling (32) is operated to impede torque transmission between the motor output shaft (44) and the differential input member (50); and the third coupling (34) is operated in a state that impedes rotation of the differential input member (50) relative to the housing (20) about the axis.

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