Straddle-type electric vehicle

Abstract

To provide a straddle-type electric vehicle that can reduce design restriction related to setting of torque of driving wheels.SOLUTION: A saddle-type electric vehicle includes: a swing arm having one end supported on a vehicle body via a pivot and the other end supporting an axle of a drive wheel; and a first motor and a second motor configured to generate torque for the drive wheel. The first motor and the second motor are arranged respectively on both sides of a plane across the plane including a center line of the pivot and a center line of the axle of the swing arm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a saddle-ride type electric vehicle in which a motor for generating torque for a drive wheel is disposed on a swing arm. [Background technology]

[0002] BACKGROUND ART A saddle-type electric vehicle is known in which a swing arm supported on the vehicle body via a pivot supports a drive wheel, and a motor disposed on the swing arm generates torque for the drive wheel (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-93628 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, increasing the torque of the drive wheels requires a larger motor, but since the space on the swing arm where the motor is located is limited, the setting of the torque of the drive wheels is subject to design constraints.

[0005] The present invention has been made to solve this problem, and has as its object to provide a saddle-ride type electric vehicle that can reduce design restrictions regarding the setting of torque for the drive wheels. [Means for solving the problem]

[0006] A first aspect for achieving this object is a saddle-type electric vehicle having a swing arm with one end supported on the vehicle body via a pivot and the other end supporting the axle of a drive wheel, and including a first motor and a second motor that generate torque for the drive wheel, the first motor and the second motor being arranged on either side of a plane that includes the center line of the pivot and the center line of the axle of the swing arm.

[0007] In the second aspect, when the swing arm is viewed from the direction in which the axle extends in the first aspect, the first motor and the second motor are arranged between the pivot and the midpoint of the line segment connecting the center line of the pivot and the center line of the axle.

[0008] In a third aspect, in the first or second aspect, the distance between the outer periphery of the first motor and the center line of the axle is equal to the distance between the outer periphery of the second motor and the center line of the axle.

[0009] In a fourth aspect, in any one of the first to third aspects, the size of the outer periphery of the first motor is different from the size of the outer periphery of the second motor.

[0010] In a fifth aspect, in any one of the first to fourth aspects, the drive wheels are positioned inside a range obtained by projecting the first motor and the second motor perpendicularly to the center line of the axle. [Effects of the Invention]

[0011] According to the present invention, a first motor and a second motor that generate torque for the drive wheels are arranged on either side of a plane that includes the center line of the pivot and the center line of the axle of the swing arm. Because the torque for the drive wheels is set by the combination of the first motor and the second motor arranged on the swing arm, design restrictions on setting the torque for the drive wheels can be reduced. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a left side view of a saddle-ride type electric vehicle according to one embodiment. [Figure 2] FIG. [Figure 3] FIG. 2 is a skeleton diagram of a reducer. [Figure 4] FIG. 10 is a skeleton diagram of a speed reducer according to a modified example. [Figure 5] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a left side view of a saddle-ride type electric vehicle 10 in one embodiment. In Fig. 1, covers, seats, etc. supported by a body 11 of the saddle-ride type electric vehicle 10 are shown by two-dot chain lines. In this embodiment, the saddle-ride type electric vehicle 10 is described as a two-wheeled vehicle with wheels arranged at the front and rear, but is not limited to this. The saddle-ride type electric vehicle 10 may also be a three-wheeled or four-wheeled vehicle with multiple wheels arranged at the front and rear.

[0014] The saddle-type electric vehicle 10 comprises a body 11 extending in the front-to-rear direction, a handlebar 13 disposed at the upper end of a steering shaft 12 supported by the body 11, a front fork 14 disposed at the lower end of the steering shaft 12, a front wheel 15 disposed at the lower end of the front fork 14, and a swing arm 16.

[0015] One end 17 of the swing arm 16 is supported by the vehicle body 11 via a pivot 18, and the other end 19 of the swing arm 16 supports an axle 21 of a drive wheel (rear wheel) 20. A suspension 22 is interposed between the end 19 of the swing arm 16 and the vehicle body 11. In this embodiment, the rear wheels are the drive wheels 20 of the saddle-ride type electric vehicle 10, but this is not limited to this. Depending on the type of saddle-ride type electric vehicle 10, the front wheels may be the drive wheels.

[0016] Fig. 2 is a left side view of the swing arm 16. Fig. 2 does not show the drive wheel 20, whose axle 21 is disposed at the end 19 of the swing arm 16. A first motor 23, a second motor 24, and a reducer 25 are disposed on the swing arm 16. The reducer 25 amplifies the torque of the first motor 23 and the second motor 24. In this embodiment, the torque of the first motor 23 and the second motor 24 is transmitted from the reducer 25 to the axle 21 via a chain 26.

[0017] An electricity storage device (not shown) that supplies power to the first motor 23 and the second motor 24 is disposed on the vehicle body 11 (see FIG. 1). Inverters (not shown) that control the rotation speeds of the first motor 23 and the second motor 24 are disposed on the swing arm 16. The first motor 23, the second motor 24, and the inverter disposed on the swing arm 16 are connected to the electricity storage device disposed on the vehicle body 11 by electric wires (not shown).

[0018] The swing arm 16 has a cantilever structure in which the first motor 23, the second motor 24, the reducer 25, and the axle 21 are arranged on one side of the swing arm 16. This improves maintainability compared to a structure in which the motor and axle are supported by a bifurcated portion of the swing arm.

[0019] The first motor 23 and the second motor 24 are disposed on either side of the plane 27, which includes the center line 18a of the pivot 18 of the swing arm 16 and the center line 21a of the axle 21. This allows the length of the space in which the first motor 23 and the second motor 24 are disposed to be shorter in the direction in which the plane 27 extends, compared to when the rotation shaft 30 of the first motor 23 (see FIGS. 3 and 4) and the rotation shaft 31 of the second motor 24 are both located on the plane 27.

[0020] When the swing arm 16 is viewed from the direction in which the axle 21 extends, the first motor 23 and the second motor 24 are disposed between the pivot 18 and a midpoint 29 of a line segment 28 connecting the center line 18a of the pivot 18 and the center line 21a of the axle 21. Compared to when the first motor 23 and the second motor 24 are disposed between the midpoint 29 and the axle 21, the moment of force of the swing arm 16 with the pivot 18 as a fulcrum is smaller, so the suspension 22 makes it easier for the swing arm 16 to swing in response to unevenness in the road surface. This improves the road-following ability of the drive wheels 20, resulting in a more comfortable ride for the saddle-ride type electric vehicle 10.

[0021] Furthermore, when the first motor 23 and the second motor 24 are disposed between the pivot 18 and a midpoint 29 of a line segment 28 connecting the center line 18a of the pivot 18 and the center line 21a of the axle 21, the rotation angle of the first motor 23 and the second motor 24 about the pivot 18 becomes smaller than when the first motor 23 and the second motor 24 are disposed between the midpoint 29 and the axle 21. Since the rotation angle of the electric wires (not shown) that carry current to the first motor 23 and the second motor 24 also becomes smaller, the influence of the swing of the swing arm 16 on the electric wires (such as wire breakage due to bending) can be reduced.

[0022] 3 is a skeleton diagram of the reducer 25. The rotation shaft 30 of the first motor 23, the rotation shaft 31 of the second motor 24, and the output shaft 32 of the reducer 25 are arranged parallel to one another. The reducer 25 includes a first mechanism 33 that transmits the power of the first motor 23 to the output shaft 32, and a second mechanism 34 that transmits the power of the second motor 24 to the output shaft 32.

[0023] The first mechanism 33 includes a first gear 35 coupled to the rotary shaft 30, and a second gear 36 rotatably disposed on the output shaft 32. The second gear 36 meshes with the first gear 35. A clutch 37 is disposed between the second gear 36 and the output shaft 32. The clutch 37 is a one-way clutch that transmits power only in a certain direction from the second gear 36 to the output shaft 32. The first mechanism 33 is set to a reduction ratio due to the meshing of the first gear 35 and the second gear 36.

[0024] The second mechanism 34 includes a third gear 38 connected to the rotary shaft 31 and a fourth gear 39 connected to the output shaft 32. The fourth gear 39 meshes with the third gear 38. The second mechanism 34 is set to a reduction ratio smaller than that of the first mechanism 33 due to the meshing between the third gear 38 and the fourth gear 39. The first mechanism 33 is a low-speed transmission path, and the second mechanism 34 is a high-speed transmission path. The chain 26 is stretched between a fifth gear 40 connected to the output shaft 32 and a sixth gear 41 connected to the axle 21.

[0025] When the second motor 24 is de-energized and the first motor 23 is driven, the clutch 37 is engaged and the reducer 25 outputs the torque of the first motor 23 to the drive wheels 20 via the first mechanism 33, which has a larger reduction ratio than the second mechanism 34. This provides a large torque when starting or traveling at low speeds, enabling powerful starting and traveling at low speeds.

[0026] When the first motor 23 is de-energized and the second motor 24 is driven, the reducer 25 outputs the torque of the second motor 24 to the drive wheels 20 via the second mechanism 34, which has a smaller reduction ratio than the first mechanism 33. This enables high-speed driving with good electricity consumption. The clutch 37 is disengaged to block the transmission of power from the output shaft 32 to the second gear 36, thereby reducing drag loss caused by the first mechanism 33 and the first motor 23 when the second motor 24 is driven.

[0027] When the first motor 23 and the second motor 24 are driven, the clutch 37 is engaged if the rotation speed of the second gear 36 driven by the first motor 23 is greater than the rotation speed of the output shaft 32 driven by the second motor 24. The reducer 25 transmits the torque of the first motor 23 and the second motor 24 to the drive wheels 20.

[0028] 4 is a skeleton diagram of a speed reducer 42 in a modified example. In the speed reducer 42, a first gear 35 connected to the rotary shaft 30 of the first motor 23 meshes with a fourth gear 39 connected to the output shaft 32, and a third gear 38 connected to the rotary shaft 31 of the second motor 24 meshes with the fourth gear 39 connected to the output shaft 32. The reduction ratio between the third gear 38 and the fourth gear 39 is smaller than the reduction ratio between the first gear 35 and the fourth gear 39.

[0029] When the second motor 24 is de-energized and the first motor 23 is driven, the reducer 42 outputs the torque of the first motor 23 to the drive wheels 20 via the first gear 35 and the fourth gear 39. This provides a large torque when starting or traveling at low speeds, enabling powerful starting and traveling at low speeds.

[0030] When the first motor 23 is de-energized and the second motor 24 is driven, the reducer 42 outputs the torque of the second motor 24 to the drive wheels 20 via the third gear 38 and the fourth gear 39. This enables high-speed running with good electricity consumption.

[0031] When the first motor 23 and the second motor 24 are driven, the reducer 42 transmits the torque of the first motor 23 and the second motor 24 to the drive wheels 20. The reducer 42 can omit the second gear 36 and the clutch 37 that are included in the reducer 25, and therefore, compared to the reducer 25, it is possible to reduce the cost by the amount of the second gear 36 and the clutch 37 and to make the reducer smaller.

[0032] Returning to Figure 2, the explanation will be made. In the saddle-ride type electric vehicle 10, the torque of the drive wheels 20 is set by the combination of the first motor 23, the second motor 24, and the reducer 25, so the first motor 23 and the second motor 24 can each be made smaller than when the torque of the drive wheels 20 is increased by increasing the size of a single motor. Since the torque of the drive wheels 20 can be increased while minimizing the increase in space required for the portions of the swing arm 16 where the first motor 23 and the second motor 24 are arranged, design constraints regarding the setting of the torque of the drive wheels 20 can be reduced.

[0033] The first motor 23 and the second motor 24 being arranged on both sides of the plane 27 means that the rotating shaft 30 of the first motor 23 (see FIGS. 3 and 4) and the rotating shaft 31 of the second motor 24 are arranged on both sides of the plane 27, with the plane 27 sandwiched between them. It is preferable that the entire rotor (not shown) of the first motor 23 and the entire stator (not shown) of the second motor 24 are arranged on both sides of the plane 27, with the plane 27 sandwiched between them, because this further reduces the length of the space in which the first motor 23 and the second motor 24 are arranged in the direction in which the plane 27 extends. In particular, it is preferable that the entire casing of the first motor 23 and the entire casing of the second motor 24 are arranged on both sides of the plane 27, with the plane 27 sandwiched between them, because this further reduces the length of the space in which the first motor 23 and the second motor 24 are arranged in the direction in which the plane 27 extends.

[0034] It is preferable that the distance D1 between the outer periphery 23a of the first motor 23 and the center line 21a of the axle 21 be equal to the distance D2 between the outer periphery 24a of the second motor 24 and the center line 21a of the axle 21. The outer periphery 23a is the outer periphery of the case of the first motor 23, and the outer periphery 24a is the outer periphery of the case of the second motor 24. The distances D1 and D2 are longer than the radius of the drive wheel 20. When the distance D1 is equal to the distance D2, the length between the pivot 18 and the axle 21 can be shortened compared to when the distances D1 and D2 are different. Furthermore, because the distances between the outer periphery of the drive wheel 20 and the outer periphery 23a of the first motor 23 and the outer periphery 24a of the second motor 24 can be secured, maintenance such as inspection of the first motor 23 and the second motor 24 and replacement of the drive wheel 20 can be facilitated.

[0035] The size S1 of the outer periphery 23a in a direction perpendicular to the rotation shaft 30 of the first motor 23 (see FIGS. 3 and 4) is different from the size S2 of the outer periphery 24a in a direction perpendicular to the rotation shaft 31 of the second motor 24. In this embodiment, the size S1 of the first motor 23 is larger than the size S2 of the second motor 24. The size S1 is the longest length across the outer periphery 23a, and the size S2 is the longest length across the outer periphery 24a.

[0036] Because the distances D1 and D2 are equal to each other, the first motor 23, which has a larger outer circumference 23a, can be positioned closer to the pivot 18 than the second motor 24, which has a smaller outer circumference 24a. Since motors with a larger outer circumference are generally heavier than motors with a smaller outer circumference, positioning the first motor 23, which is heavier than the second motor 24, closer to the pivot 18 is advantageous in reducing the force moment of the swing arm 16, which has its fulcrum at the pivot 18. This is therefore advantageous in improving the road-following ability of the drive wheels 20.

[0037] In this embodiment, the large first motor 23 is disposed vertically above the plane 27, and the small second motor 24 is disposed vertically below the plane 27. Conversely, compared to when the large first motor 23 is disposed below the plane 27, the distance between the motor disposed below the plane 27 and the road surface with which the drive wheels 20 contact can be made longer. Therefore, when there is an obstacle such as a step on the road surface, the possibility of the obstacle hitting the motor and damaging the motor can be reduced.

[0038] Fig. 5 is a plan view of the swing arm 16. In Fig. 5, the chain 26 stretched between the reducer 25 and the axle 21 and the like are not shown.

[0039] The drive wheel 20 is located inside a range 43 obtained by radially projecting the first motor 23 and the second motor 24 perpendicular to the center line 21a of the axle 21. The width of the range 43 is equal to the height from the swing arm 16 of the portions of the first motor 23 and the second motor 24 that protrude most from the swing arm 16. Because the drive wheel 20 fits within the range 43, the swing arm 16 on which the first motor 23, the second motor 24, and the drive wheel 20 are arranged can be easily mounted on the vehicle body 11. Furthermore, because the reducer 25 fits within the range 43, the swing arm 16 on which the first motor 23, the second motor 24, the reducer 25, and the drive wheel 20 are arranged can be easily mounted on the vehicle body 11.

[0040] The present invention has been described above based on an embodiment, but the present invention is not limited to this embodiment in any way, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0041] In the embodiment, the case where the size S1 of the first motor 23 is larger than the size S2 of the second motor 24 has been described, but this is not necessarily limited to this. It is of course possible to make the size S1 of the first motor 23 the same as the size S2 of the second motor 24, or to make the size S1 of the first motor 23 smaller than the size S2 of the second motor 24.

[0042] The speed reducer 25 described in the embodiment is an example and is not limited to this. The relationship between the reduction ratio of the first mechanism 33 and the reduction ratio of the second mechanism 34 of the speed reducer 25 is also set appropriately depending on the rated torque of the first motor 23 and the second motor 24 and the required torque of the drive wheels 20.

[0043] In the embodiment, the clutch 37 is a one-way clutch, but this is not necessarily limited to this. Naturally, a dog clutch or a friction clutch can be used instead of the one-way clutch.

[0044] In the embodiment, the case where the reduction ratio between the third gear 38 and the fourth gear 39 is smaller than the reduction ratio between the first gear 35 and the fourth gear 39 in the speed reducer 42 of the modified example has been described, but this is not necessarily limited to this. It is of course possible to make the reduction ratio between the third gear 38 and the fourth gear 39 the same as or larger than the reduction ratio between the first gear 35 and the fourth gear 39.

[0045] In the embodiment, the swing arm 16 has been described as having a cantilever structure in which the first motor 23, the second motor 24, the speed reducer 25, and the axle 21 are arranged on one side of the swing arm 16, but this is not necessarily limited to this. For example, it is of course possible to provide a bifurcated portion on the swing arm, install an axis (pivot) on the bifurcated portion, and arrange the first motor 23, the second motor 24, and the speed reducer 25 on the bifurcated portion. In this case as well, a cantilever structure in which the axle 21 is arranged on one side of the swing arm 16 is preferable because it provides excellent maintainability, such as for replacing the drive wheel 20. [Explanation of symbols]

[0046] 10 Saddle-type electric vehicle 11 Body 16 Swingarm 17,19 End 18 Pivot 18a center line 20 drive wheels 21 axles 21a center line 23 First motor 23a outer circumference 24 Second motor 24a outer circumference 27 plane 28 line segments 29 Midpoint 43 Range

Claims

1. a swing arm having one end supported on a vehicle body via a pivot and the other end supporting an axle of a drive wheel; a first motor and a second motor that generate torque for the drive wheels; The first motor and the second motor are disposed on either side of a plane that includes a center line of the pivot and a center line of the axle of the swing arm.

2. 2. The saddle-ride type electric vehicle according to claim 1, wherein, when the swing arm is viewed from a direction in which the axle extends, the first motor and the second motor are disposed between the pivot and a midpoint of a line segment connecting a center line of the pivot and a center line of the axle.

3. 3. The saddle-type electric vehicle according to claim 2, wherein the distance between the outer periphery of the first motor and the center line of the axle is equal to the distance between the outer periphery of the second motor and the center line of the axle.

4. 4. The saddle-type electric vehicle according to claim 3, wherein the outer periphery of the first motor is different from the outer periphery of the second motor.

5. 5. The saddle-type electric vehicle according to claim 1, wherein the drive wheel is located inside a range obtained by projecting the first motor and the second motor perpendicular to a center line of the axle.

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