Vehicle drive system

Abstract

Aspects of the present invention relate to a drive system for an electric or hybrid vehicle, comprising a first input shaft rotatable about a first input axis, a second input shaft rotatable about a second input axis, a first output shaft rotatable about a first output axis, a second output shaft rotatable about a second output axis, a first gear assembly arranged to transfer torque from the first input shaft to the first output shaft, and a second gear assembly arranged to transfer torque from the second input shaft to the second output shaft. The first input axis is axially offset with respect to the second input axis, and the first output axis, the second output axis and the first input axis are coaxially aligned with one another.

Description

[0001] VEHICLE DRIVE SYSTEM

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a vehicle drive system. Aspects of the invention relate to a drive system for an electric or hybrid vehicle, and to a vehicle.

[0004] BACKGROUND

[0005] It is known to provide a drive system in a vehicle, where the drive system provides torque vectoring. In such systems, individual ones of a pair of wheels may be independently drivable by the drive system relative to one another. In torque vectoring-capable drive systems of electric and hybrid vehicles, a pair of electric motors and a pair of transmissions (i.e. gear sets) are often provided. The provision of these components gives rise to challenges concerning the space envelope occupied by the drive system.

[0006] It is an aim of embodiments of the present invention to address one or more of the disadvantages associated with the prior art.

[0007] SUMMARY OF THE INVENTION

[0008] Aspects and embodiments of the invention provide a drive system for an electric or hybrid vehicle, and a vehicle.

[0009] According to an aspect of the present invention there is provided a drive system for an electric or hybrid vehicle, comprising: a first input shaft rotatable about a first input axis; a second input shaft rotatable about a second input axis; a first output shaft rotatable about a first output axis; and a second output shaft rotatable about a second output axis; wherein the first input axis is axially offset with respect to the second input axis; and the first output axis, the second output axis and the first input axis are coaxially aligned with one another.

[0010] The drive system may further comprise: a first gear assembly arranged to transfer torque from the first input shaft to the first output shaft; and a second gear assembly arranged to transfer torque from the second input shaft to the second output shaft.

[0011] The drive system may therefore provide torque vectoring to wheels rotationally coupled to the first output shaft and the second output shaft whilst optimising space utilisation compared to known arrangements.

[0012] In certain embodiments, the first input axis is parallel to the second input axis. This provides a particularly compact arrangement. In certain embodiments, the drive system may comprise a first bearing connecting the first input shaft to the first output shaft but permitting independent rotation of the first output shaft relative to the first input shaft. The first input shaft and the first output shaft may therefore mutually support one another through the first bearing.

[0013] In certain embodiments, the first gear assembly includes a first intermediate shaft that is rotatable about a first intermediate axis, the first intermediate axis being axially offset with respect to the first input axis and the first output axis. In this manner, the gearing provided by the first gear assembly between the first input shaft and the first output shaft is provided (at least partially) along the first intermediate axis which is offset from the first input axis and the first output axis. This therefore avoids axially lengthening the drive system to accommodate the first gear assembly entirely along an axis parallel and coaxial with the first input axis and the first output axis.

[0014] In certain embodiments, the second gear assembly includes a second intermediate shaft that is rotatable about a second intermediate axis, the second intermediate axis being axially offset with respect to the second input axis and the second output axis. In certain embodiments, the first intermediate axis may be coaxially aligned with the second intermediate axis. Such arrangements are particularly effective and yet compact compared to known arrangements.

[0015] In certain embodiments, the first gear assembly includes a first intermediate input gear for receiving drive from the first input shaft, and a first intermediate output gear for driving the first output shaft, wherein the first intermediate input gear and the first intermediate output gear are coaxially arranged relative to one another. In certain embodiments, the second gear assembly includes a second intermediate input gear for receiving drive from the second input shaft, and a second intermediate output gear for driving the second output shaft, wherein the second intermediate input gear and the second intermediate output gear are coaxially arranged relative to one another. Such arrangements are particularly effective and yet compact compared to known arrangements.

[0016] In certain embodiments, the drive system comprises a first electric motor arranged to drive the first input shaft and a second electric motor arranged to drive the second input shaft.

[0017] In certain embodiments, the first electric motor and the second electric motor are disposed along a first axis that is perpendicular to the first output axis and the second output axis. This overlap optimises space utilisation.

[0018] In certain embodiments, the first electric motor is arranged to drive the first input shaft in a first direction and the second electric motor is arranged to drive the second input shaft in a second direction that is opposite the first direction. Such arrangements are particularly effective and yet compact compared to known arrangements. In certain embodiments, the distance between the second input axis and the second output axis (which is coaxial with the first output axis) is less than or equal to the sum of centre distances of gear sets (i.e. engaging pairs of gears) along the torque path defined by the second gear assembly. Such an arrangement is particularly compact compared to known arrangements.

[0019] In certain embodiments, the drive system comprises a frame that is arranged to support one or more of the first input shaft, the second input shaft, the first output shaft, and the second output shaft. The frame may be dedicated to this function or it may have other functions within the vehicle (e.g. supporting other features).

[0020] In certain embodiments, the drive system may comprise a first vehicle wheel on the first output shaft or otherwise drivable by the first output shaft, and a second vehicle wheel on the second output shaft or otherwise drivable by the second output shaft.

[0021] According to another aspect of the present invention there is provided a vehicle comprising a drive system as described above. The vehicle may be an electric or hybrid vehicle. With the electric motors overlapping and at least one of them offset with respect to the first and second output shafts, and the motors and gear assemblies being disposed in a single frame, a particularly compact arrangement may be provided. Each gear assembly may be disposed in a housing mounted in the frame, each housing containing lubricant for the gears.

[0022] Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0025] FIG. 1 shows a schematic view of a drive system for an electric or hybrid vehicle in accordance with an embodiment of the present invention; and

[0026] FIG. 2 shows a vehicle in accordance with an embodiment of the present invention.

[0027] DETAILED DESCRIPTION

[0028] FIG. 1 shows a schematic view of a drive system 10 for an electric or hybrid vehicle 70 (shown in FIG. 2) in accordance with an embodiment of the present invention. The drive system 10 includes a first input shaft 12 that is rotatably drivable by a first electric motor 60 about a first input axis 14 in the direction indicated by arrow 74 in FIG. 1. Similarly, the drive system 10 includes a second input shaft 16 that is rotatably drivable about a second input axis 18 by a second electric motor 62 in the direction indicated by arrow 76 in FIG. 1 . Thus, in the depicted embodiment, the drives to the respective input shafts 12, 16 are in opposite directions 74, 76, that is, on opposite sides of the drive system 10.

[0029] The drive system 10 further includes a first output shaft 20 that is rotatable about a first output axis 22 and a second output shaft 24 that is rotatable about a second output axis 26. A first gear assembly 28 is provided and is arranged to transfer torque (i.e. along a torque path) from the first input shaft 12 to the first output shaft 20. Similarly, a second gear assembly 30 is provided and arranged to transfer torque (i.e. along a torque path) from the second input shaft 16 to the second output shaft 24.

[0030] The drive system 10 is arranged so that the first input axis 14 is axially offset with respect to the second input axis 18. That is, the first input axis 14 is not coaxial with the second input axis 18.

[0031] In the depicted embodiment, the first input axis 14 is parallel to the second input axis 18. Additionally, the first output axis 22, the second output axis 26, and the first input axis 14 are all coaxially aligned with one another. In the non-limiting embodiment shown in FIG. 1 , a first bearing 34 is provided that connects the first input shaft 12 to the first output shaft 20. Whilst structurally coupling the first input shaft 12 to the first output shaft 20 (and thereby permitting mutual support of the first input shaft 12 and the first output shaft 20), the first bearing 34 permits independent rotation of the first output shaft 20 relative to the first input shaft 12. That is, each of the first output shaft 20 and the first input shaft 12 may rotate about the respective (but coaxial) first output axis 22 and first input axis 14 independently of one another. In alternative embodiments, the first gear assembly 28 may be a coaxial gear train that rotationally couples the first input shaft 12 to the first output shaft 20.

[0032] In the non-limiting embodiment shown in FIG. 1 , the first electric motor 60 and the second electric motor 62 are disposed along a first overlap axis 64, wherein the first overlap axis 64 is perpendicular to each of the first output axis 22 and the second output axis 26 (both of which are also parallel to and coaxial with the first input axis 14). That is, at least a part of each of the first electric motor 60 and the second electric motor 62 overlap (i.e. are aligned) with one another along the first axis 64. The distance between the second input axis 18 and the second output axis 26 (which is coaxial with the first output axis 22) is less than or equal to the sum of centre distances of gear sets (i.e. engaging pairs of gears) along the torque path defined by the second gear assembly 30. In the embodiment shown in FIG. 1 . The first axis 64 may be coincident with a second axis 72 being a central longitudinal axis of the vehicle in which the drive system 10 is installed. In other embodiments, this may not necessarily be the case.

[0033] In the non-limiting embodiment shown in FIG. 1 , the first gear assembly 28 includes a first intermediate shaft 36 that is rotatable about a first intermediate axis 38. The first intermediate axis 38 is axially offset with respect to the first input axis 14 and the first output axis 22. That is, the first intermediate axis 38 is not coaxial with either of the first input axis 14 and the first output axis 22. In the non-limiting embodiment shown in FIG. 1 , the first gear assembly 28 includes a first input gear 40 disposed on and drivable by the first input shaft 12. As shown, the first gear assembly 28 may also include a first intermediate input gear 42 disposed on the first intermediate shaft 36. In such an arrangement, the first intermediate input gear 42 may be drivable by the first input gear 40 such that rotation of the first intermediate input gear 42 causes rotation of the first intermediate shaft 36 about the first intermediate axis 38.

[0034] In the non-limiting embodiment shown in FIG. 1 , the first gear assembly 28 further includes a first intermediate output gear 44 disposed on and drivable by the first intermediate shaft 36. As shown, the first gear assembly 28 may also include a first output gear 46 disposed on the first output shaft 20. In such an arrangement, the first output gear 46 may be drivable by the first intermediate output gear 44 such that rotation of the first output gear 46 causes rotation of the first output shaft 20 about the first output axis 22. As shown, the first intermediate input gear 42 and the first intermediate output gear 44 may be coaxially arranged relative to one another. In certain embodiments, the first intermediate shaft 36 may comprise multiple shafts that are rotatably coupled to one another. In the depicted embodiment, the first gear assembly 28 "steps out" from the first input axis 14 to the first intermediate axis 38, and “steps in” from the first intermediate axis 38 to the first output shaft 20 (which is coaxially aligned with the first input axis 14). In certain embodiments, additional shafts (and associated gears) that may be parallel to but offset from the first intermediate shaft 36 may be provided as part of the first gear assembly 28. In certain embodiments, the first gear assembly 28 may rotationally couple the first input shaft 14 to the first output shaft 24 without the presence of the first intermediate shaft 48

[0035] In the non-limiting embodiment shown in FIG. 1 , the second gear assembly 30 includes a second intermediate shaft 48 that is rotatable about a second intermediate axis 50. The second intermediate axis 50 is axially offset with respect to (and lies between) the second input axis 18 and the second output axis 26. That is, the second intermediate axis 50 is not coaxial with either the second input axis 18 or the second output axis 26. As shown, the second intermediate axis 50 may be coaxial with the first intermediate axis 38.

[0036] In the non-limiting embodiment shown in FIG. 1 , the second gear assembly 30 includes a second input gear 52 disposed on and drivable by the second input shaft 16. As shown, the second gear assembly 30 may also include a second intermediate input gear 54 disposed on the second intermediate shaft 48. In such an arrangement, the second intermediate input gear 54 may be drivable by the second input gear 52 such that rotation of the second intermediate input gear 54 causes rotation of the second intermediate shaft 48 about the second intermediate axis 50.

[0037] In the non-limiting embodiment shown in FIG. 1 , the second gear assembly 30 further includes a second intermediate output gear 56 disposed on and drivable by the second intermediate shaft 48. As shown, the second gear assembly 30 may also include a second output gear 58 disposed on the second output shaft 24. In such an arrangement, the second output gear 58 may be drivable by the second intermediate output gear 56 such that rotation of the second output gear 58 causes rotation of the second output shaft 24 about the second output axis 26. As shown, the second intermediate input gear 54 and the second intermediate output gear 56 may be coaxially arranged relative to one another. In certain embodiments, the second intermediate shaft 48 may comprise multiple shafts that are rotatably coupled to one another. In the depicted embodiment, the second gear assembly 30 "steps out" from the second input axis 18 to the second intermediate axis 50, and “steps out” once more from the second intermediate axis 50 to the second output shaft 24 (which is axially offset with respect to the second input axis 18). In this sense, the second gear assembly 30 may comprise a parallel offset layshaft gear train. In certain embodiments, additional shafts (and associated gears) that may be parallel to but offset from the second intermediate shaft 48 may be provided as part of the second gear assembly 30. In certain embodiments, the second gear assembly 30 may rotationally couple the second input shaft 16 to the second output shaft 24 without the presence of the second intermediate shaft 48.

[0038] In certain embodiments, any one or more gears of the first gear assembly 28 and the second gear assembly 30 may be a pinion gear.

[0039] FIG. 1 shows a frame 32 of the drive system 10, wherein the frame 32 supports the first input shaft 12, the second input shaft 16, the first output shaft 20, and the second output shaft 24. The frame 32 may be a dedicated frame of the drive system 10, or it may be another frame or structure of the vehicle 70. In certain embodiments, the frame 32 may support a selection (i.e. any one or more) of the first input shaft 12, the second input shaft 16, the first output shaft 20, and the second output shaft 24.

[0040] In the non-limiting embodiment shown in FIG. 1 , the drive system 10 includes a first vehicle wheel 66 that is drivable by the first output shaft 20, and a second vehicle wheel 68 that is drivable by the second output shaft 24. In certain embodiments, the first vehicle wheel 66 may be disposed on the first output shaft 20 and / or the second vehicle wheel 68 may be disposed on the second output shaft 24.

[0041] The above-described arrangement permits each of the first vehicle wheel 66 and the second vehicle wheel 68 to be driven independently of one another. The drive system 10 therefore permits torque vectoring whilst maintaining a more compact space envelope (i.e. the space occupied by the drive system 10) compared with other known arrangements. Moreover, embodiments of the present invention may allow flexibility in utilising electric motors and / orgearassemblies ofdifferent types or sizes whilst maintaining a compact space envelope. The drive system 10 according to embodiments of the present invention may therefore be of particular benefit during the development of a vehicle, when determining an optimal combination of electric motors and gear assemblies, or it may provide a platform system that may be utilised across a range of vehicles which each have distinct electric motor and gearing requirements.

[0042] FIG. 2 shows a vehicle 70 in accordance with an embodiment of the present invention. The vehicle 70 may be an electric or hybrid vehicle. The vehicle 70 may comprise the drive system 10 described above.

[0043] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS1 . A drive system for an electric or hybrid vehicle, comprising: a first input shaft rotatable about a first input axis; a second input shaft rotatable about a second input axis; a first output shaft rotatable about a first output axis; a second output shaft rotatable about a second output axis; a first gear assembly arranged to transfer torque from the first input shaft to the first output shaft; and a second gear assembly arranged to transfer torque from the second input shaft to the second output shaft; wherein the first input axis is axially offset with respect to the second input axis; and the first output axis, the second output axis and the first input axis are coaxially aligned with one another.

2. A drive system according to claim 1 , wherein the first input axis is parallel to the second input axis.

3. A drive system according to claim 1 or 2, comprising a first bearing connecting the first input shaft to the first output shaft but permitting independent rotation of the first output shaft relative to the first input shaft.

4. A drive system according to any preceding claim, wherein the first gear assembly includes a first intermediate shaft that is rotatable about a first intermediate axis, the first intermediate axis being axially offset with respect to the first input axis and the first output axis.

5. A drive system according to any preceding claim, wherein the second gear assembly includes a second intermediate shaft that is rotatable about a second intermediate axis, the second intermediate axis being axially offset with respect to the second input axis and the second output axis.

6. A drive system according to claim 5 when dependent on claim 4, wherein the first intermediate axis is coaxially aligned with the second intermediate axis.

7. A drive system according to any preceding claim, wherein the first gear assembly includes a first intermediate input gear for receiving drive from the first input shaft, and a first intermediate output gear for driving the first output shaft, wherein the first intermediate input gear and the first intermediate output gear are coaxially arranged relative to one another.

8. A drive system according to any preceding claim, wherein the second gear assembly includes a second intermediate input gear for receiving drive from the second input shaft, and a second intermediate output gear for driving the second output shaft, wherein the second intermediate input gear and the second intermediate output gear are coaxially arranged relative to one another.

9. A drive system according to any preceding claim, comprising a first electric motor arranged to drive the first input shaft and a second electric motor arranged to drive the second input shaft.

10. A drive system according to claim 9, wherein the first electric motor and the second electric motor are disposed along a first overlap axis that is perpendicular to the first output axis and the second output axis.11 . A drive system according to claim 9 or 10, wherein the first electric motor is arranged to drive the first input shaft along a first direction and the second electric motor is arranged to drive the second input shaft along a second direction that is opposite the first direction.

12. A drive system according to any preceding claim, comprising a frame that is arranged to support one or more of the first input shaft, the second input shaft, the first output shaft, and the second output shaft.

13. A drive system according to any preceding claim, comprising a first vehicle wheel on the first output shaft or otherwise drivable by the first output shaft, and a second vehicle wheel on the second output shaft or otherwise drivable by the second output shaft.

14. A vehicle comprising a drive system according to any preceding claim.

15. A vehicle as claimed in claim 14 wherein the first overlap axis is aligned with a second longitudinal axis of the vehicle.

Images