Electric vehicle and driving system for electric vehicle

Abstract

A driving system for an electric vehicle comprises a motor (3) comprising a first output shaft (11) and a gearbox (17) comprising a second output shaft (27) attachable to a wheel (33) of the electric vehicle. The first output shaft (11) is capable of driving the second output shaft (27) to rotate by engagement of gears of the gearbox (17). The first output shaft (11) is hollow, and the second output shaft (27) extends through the first output shaft (11) so that the second output shaft (27) is disposed coaxially with the first output shaft (11). An electric vehicle comprising the driving system is disclosed. The driving system is possible to improve the balancing, the passing ability and the visual appearance of the electric vehicle.

Claims

1. A driving system (1) for an electric vehicle, the driving system comprising: a wheel rim rotatable about an axis, the wheel rim defining an interior space radially inside the rim within an axial extent of the rim; a motor (3) comprising a first output shaft (11); and a gearbox (17) comprising a second output shaft (27) drivingly attached to the wheel rim, the first output shaft (11) being capable of driving the second output shaft (27) to rotate by engagement of gears of the gearbox (17); wherein the first output shaft (11) is hollow, and the second output shaft (27) extends through the first output shaft (11) so that the second output shaft (27) is disposed coaxially with the first output shaft (11), and wherein the rim (35) and the gearbox (17) are positioned on opposite axial sides of the motor (3), and the motor (3) is at least partially positioned within the interior space defined by the rim (35).

2. The driving system (1) for the electric vehicle according to claim 1, wherein the motor (3) further comprises a motor housing (5), a stator (7) disposed fixedly within the motor housing (5), and a rotor (9) disposed rotatably within a central space defined by the stator (7), wherein the first output shaft (11) is fixed onto the rotor (9) and supported rotatably by the motor housing (5) to be rotatable with the rotor (9).

3. The driving system (1) for the electric vehicle according to claim 1, wherein the gearbox (17) comprises a gearbox housing (19), at least two pair of gears (21a, 21b, 23a, 23b) engaged with each other and at least one transmission shaft (25) supported rotatably by the gearbox housing (19), wherein the first output shaft (11) extends into the gearbox housing (19) so that a gear (21a) having a smaller diameter of a first pair of gears of the at least two pair of gears is fixed onto the first output shaft (11), a gear (23b) having a larger diameter of a last pair of gears of the at least two pair of gears is fixed onto the second output shaft (27) supported rotatably, and the other gears of the at least two pair of gears are fixed onto the at least one transmission shaft (25).

4. The driving system (1) for the electric vehicle according to claim 1, wherein the motor (3) comprises a motor housing (5) having a first main body (5a) and a first end cover (5b) attached to the first main body (5a), the gearbox (17) comprises a gearbox housing (19) having a second main body (19a) and a second end cover (19b) attached to the second main body (19a), and the first main body (5a) of the motor housing (5) and the second main body (19a) of the gearbox housing (19) are formed into a unitary unit or piece.

5. The driving system (1) for the electric vehicle according to claim 1, wherein the second output shaft (27) is attached to the wheel rim (35) by means of an adaptor (39).

6. The driving system (1) for the electric vehicle according to claim 1, wherein the wheel rim (35) is designed so that a majority of the motor (3) is positioned within the interior space defined by the wheel rim (35).

7. The driving system (1) for the electric vehicle according to claim 1, wherein an attachment point (43) for attaching the driving system (1) to a frame of the electric vehicle is formed on the gearbox (17).

8. An electric vehicle comprising a driving system (1) according to claim 1.

9. The electric vehicle according to claim 8, wherein the electric vehicle is an electric motorcycle.

10. The electric vehicle according to claim 8, wherein the electric vehicle is an electric car.

11. The electric vehicle according to claim 8, wherein the motor (3) further comprises a motor housing (5), a stator (7) disposed fixedly within the motor housing (5), and a rotor (9) disposed rotatably within a central space defined by the stator (7), wherein the first output shaft (11) is fixed onto the rotor (9) and supported rotatably by the motor housing (5) to be rotatable with the rotor (9).

12. The electric vehicle according to claim 8, wherein the gearbox (17) comprises a gearbox housing (19), at least two pair of gears (21a, 21b, 23a, 23b) engaged with each other and at least one transmission shaft (25) supported rotatably by the gearbox housing (19), wherein the first output shaft (11) extends into the gearbox housing (19) so that a gear (21a) having a smaller diameter of a first pair of gears of the at least two pair of gears is fixed onto the first output shaft (11), a gear (23b) having a larger diameter of a last pair of gears of the at least two pair of gears is fixed onto the second output shaft (27) supported rotatably, and the other gears of the at least two pair of gears are fixed onto the at least one transmission shaft (25).

13. The electric vehicle according to claim 8, wherein the motor (3) comprises a motor housing (5) having a first main body (5a) and a first end cover (5b) attached to the first main body (5a), the gearbox (17) comprises a gearbox housing (19) having a second main body (19a) and a second end cover (19b) attached to the second main body (19a), and the first main body (5a) of the motor housing (5) and the second main body (19a) of the gearbox housing (19) are formed into a unitary unit or piece.

14. The electric vehicle according to claim 8, wherein the second output shaft (27) is attached to the wheel rim (35) by means of an adaptor (39).

15. The electric vehicle according to claim 14, wherein the wheel rim (35) is designed so that a majority of the motor (3) is positioned within the interior space defined by the wheel rim (35).

16. The electric vehicle according to claim 8, further comprising a frame, wherein the driving system is attached to the frame at an attachment point (43) formed on the gearbox (17).

17. The electric vehicle according to claim 8, further comprising a wheel, wherein the wheel includes the wheel rim and a tire.

18. The driving system (1) for the electric vehicle according to claim 1, further comprising a wheel, wherein the wheel includes the wheel rim and a tire.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view showing schematically a driving system for an electric vehicle according to a preferred embodiment of the present invention being mounted onto a wheel of the electric vehicle.

(2) FIG. 2 is a bottom view of the driving system shown in FIG. 1.

(3) FIG. 3 is a sectional view taken along a line 3-3 of FIG. 1.

(4) FIGS. 4 and 5 are perspective views showing schematically that a swing arm for attaching the wheel and the driving system to a frame of the electric vehicle is attached to the driving system shown in FIG. 1

DETAILED DESCRIPTION

(5) Preferred embodiments of the present invention are described in detail with reference to illustrative examples hereinafter. For those skilled in the art, it should be understood that embodiments are only for the purpose of illustrating and are not to be construed as limiting the present invention.

(6) FIG. 1 is a side view showing schematically a driving system for an electric vehicle according to a preferred embodiment of the present invention being mounted onto a wheel of the electric vehicle, FIG. 2 is a bottom view of the driving system shown in FIG. 1, and FIG. 3 is a sectional view taken along a line 3-3 of FIG. 1. As shown in FIGS. 1-3, a driving system 1 for an electric vehicle according to a preferred embodiment of the present invention comprises a motor 3 having a motor housing 5, a stator 7 disposed fixedly within the motor housing 5, a rotor 9 disposed rotatably within the motor housing 5, and a first output shaft 11 rotatable with the rotor 9. The motor housing 5 comprises a main body 5a and an end cover 5b attached to the main body 5a. The stator 7 comprises a stator core 7a and a stator winding 7b wound on the stator core 7a. The first output shaft 11 is hollow, extends centrally through the rotor 9 and is fixed onto the rotor 9. The first output shaft 11 is supported rotatably at two ends by a first pair of bearings 13a, 13b disposed in the main body 5a and the end cover 5b of the motor housing 5 respectively so that the rotor 9 mounted fixedly onto the first output shaft 11 is disposed rotatably within a central space defined by the stator 7.

(7) The driving system 1 for an electric vehicle according to a preferred embodiment of the present invention further comprises a gearbox 17 having a gearbox housing 19, a first pair of gears 21a, 21b engaged with each other, a second pair of gears 23a, 23b engaged with each other, a transmission shaft 25, and a second output shaft 27. Each of the pair of gears has different diameter to reduce a rotating speed of the second output shaft 27. The gearbox housing 19 comprises a main body 19a and an end cover 19b attached to the main body 19a. The first output shaft 11 of the motor 3 extends into the gearbox housing 19 so that a gear 21a having a smaller diameter of the first pair of gears 21a, 21b is fixed onto the first output shaft 11 of the motor 3. A gear 21b having a larger diameter of the first pair of gears 21a, 21b is fixed onto the transmission shaft 25 which is supported rotatably at two ends by a second pair of bearings 29a, 29b disposed in the main body 19a and the end cover 19b of the gearbox housing 19 respectively. A gear 23a having a smaller diameter of the second pair of gears 23a, 23b is also fixed onto the transmission shaft 25. The second output shaft 27 of the gearbox 17 extends through the first output shaft 11 of the motor 3 which is hollow so that the second output shaft 27 of the gearbox 17 is disposed coaxially with the first output shaft 11. The second output shaft 27 is supported rotatably at two ends by a third pair of bearings 31a, 31b disposed in the end cover 5b of the motor housing 5 and the end cover 19b of the gearbox housing 19 respectively. A gear 23b having a larger diameter of the second pair of gears 23a, 23b is fixed onto a first end 27a of the second output shaft 27. A second end 27b opposite to the first end 27a of the second output shaft 27 protrudes out of the first output shaft 11 of the motor 3.

(8) The second end 27b of the second output shaft 27 may be attached to a wheel 33 of the electric vehicle. The wheel 33 comprises a rim 35 and a tire 37 which is fitted around the rim 33. The second end 27b of the second output shaft 27 is attached fixedly to the rim 35 by means of an adaptor 39. A disc brake 41 may be fitted onto the adaptor 39 to stop the wheel 33 by clamping the disc brake 41 with a braking clipper (not shown in the drawings). It should be understood that the disc brake 41 may be replaced with a drum brake or other braking system.

(9) Although the motor housing 5 and the gearbox housing 19 may be formed separately from each other and then be assembled together, it is preferred that the main body 5a of the motor housing 5 and the main body 19a of the gearbox housing 19 are formed into an unitary unit or piece to simplify the assembling process and reduce the material and the cost. Further, in the preferred embodiment, the gearbox 17 is shown to include a two-stage reduction gear set. It should be understood that it is possible to use a more than two-stage reduction gear set. The first pair of gears 21a, 21b and the second pair of gears 23a, 23b may be any applicable gear pairs, for example helical gear pairs.

(10) FIGS. 4 and 5 are perspective views showing schematically that a swing arm for attaching the wheel and the driving system to a frame of the electric vehicle is attached to the driving system shown in FIG. 1. In the example of FIGS. 4 and 5, the wheel and the driving system are shown to be attached to a frame (not shown in the drawings) of an electric motorcycle. A swing arm 45 for attaching the wheel and the driving system to the frame of the electric vehicle is fork-shaped. The rear end of fork-shaped swing arm 45 is attached at one side to an attachment point 43 formed on the gearbox 17 and at the other side to the second output shaft 27 by means of a support bearing (invisible in the drawings). The front end of fork-shaped swing arm 45 may be attached to the frame of the electric vehicle. A shock absorber 47 may be disposed between the fork-shaped swing arm 45 and the frame of the electric vehicle to damp the vibration during travelling of the vehicle. It should be understood that the driving system for the electric vehicle according to the present invention is applicable to the electric vehicle other than the electric motorcycle, for example an electric car.

(11) The operation of the driving system 1 for the electric vehicle according to the present invention will be described in detail. When a current is supplied to the motor 3, the first output shaft 11 of the motor 3 rotates with the rotor 9. The first output shaft 11 of the motor 3 drives the transmission shaft 25 to rotate by means of engagement of the first pair of gears 21a, 21b. The transmission shaft 25 further drives the second output shaft 27 to rotate by means of engagement of the second pair of gears 23a, 23b. The second output shaft 27 attached fixedly to the rim 35 further drives the wheel 33 of the electric vehicle, thereby driving finally the electric vehicle to run a road.

(12) As shown in FIG. 3, the second output shaft 27 of the gearbox 17 extends through the first output shaft 11 of the motor 3 so that the wheel 33 and the gearbox 17 are positioned either side of the motor 3, which causes a more uniform and symmetrical distribution of the weight of the driving system 1 attached to the wheel of the electric vehicle, thereby substantially improving the balancing of the driving system and thus the electric vehicle. The motor 3 is at least partially positioned within a space defined by the rim, which reduces the size of the electric vehicle fitted with the driving system according to the present invention, thereby improving the passing ability and the visual appearance of the electric vehicle. Even for a driving system with a large power density and an increased size, a majority of the motor of the driving system also may be positioned within the space defined by the rim by designing the shape of the rim.

(13) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.

(14) In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. A single processor or other unit may fulfil the functions of several items re-cited in the claims. The mere fact that certain measures are re-cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.