EP2643201A1

EP2643201A1 - Electric vehicle

Info

Publication number: EP2643201A1
Application number: EP11799880.7A
Authority: EP
Inventors: Hirotoshi Yamauchi
Original assignee: Yamaha Motor Co Ltd
Current assignee: Yamaha Motor Co Ltd
Priority date: 2010-11-22
Filing date: 2011-11-21
Publication date: 2013-10-02
Also published as: WO2012070222A1; JP5453550B2; JPWO2012070491A1; TWI457250B; TW201226229A; TWI486283B; WO2012070491A1; EP2644494A1; EP2644494A4; JP5559939B2; JP2013541451A; TW201233584A

Abstract

A speed reducing mechanism 131 connected to an electric motor 5 includes an input gear 140, an intermediate gear 142, and an output gear 144. At least a part of the intermediate gear 142 is disposed at a position overlapping with a stator 82 of the electric motor 5 in a side view. A part of the intermediate gear 142 is disposed to overlap in position in a right-left direction Y1 with a wheel member 148. A motor shaft 85, an intermediate shaft 141, and an axle 143 are disposed in that order from the front. In a side view, a front end part 82b of the stator 82 is disposed further forward than the wheel member 148.

Description

ELECTRIC VEHICLE

This invention relates to an electric vehicle.

An electric vehicle that uses an electric motor as a power source includes a battery, the electric motor to which an electric power of the battery is supplied, and a rear wheel driven by the electric motor (see Patent Document 1, for example). The electric motor includes a rotor and a stator. The stator has a coil through which an electric current from the battery flows and generates heat due to the supply of an electric current to the coil. The electric motor generates a large output for accelerating the electric vehicle and is thus high in heat generation amount. Countermeasures against the heat generated by the electric motor are thus essential. That is, one of the important issues in an electric vehicle is how to cool the electric motor.

The arrangement described in Patent Document 1 is provided with a cooling fan and the electric motor is cooled by the cooling fan. The cooling fan is disposed inside a swing arm to which the electric motor and the rear wheel are mounted. Wind from the cooling fan passes through an interior of the electric motor and is thereafter discharged to the atmosphere. The electric motor is thereby cooled from its interior.

[PTL 1] JP-A-2010-83366

With an electric vehicle, there may be a case where the output of the electric motor is temporarily increased above a rated output to achieve a high acceleration rate during acceleration. In this case, a larger amount of an electric current flows through the coil of the electric motor and the heat generation amount of the electric motor increases significantly in comparison to a state in which an output no greater than the rated output is being generated. The need to cool the electric motor thus becomes greater.

In this case, cooling of the electric motor by forcibly supplying cooling air to the electric motor by a cooling fan as in Patent Document 1 may be considered. However, space for installing parts is narrow inside the swing arm. Further, the electric motor, a speed reduction mechanism for speed-reducing and transmitting the output of the electric motor to the rear wheel, etc., are housed in the swing arm and there is no leeway in installation space. Simplification of the cooling fan or other structure for cooling the electric motor is thus important.

Here, the present inventor made a change of approach to the issue from how to cool the electric motor to how to decrease the heat generation amount of the electric motor. If the heat generation amount of the electric motor can be decreased, the electric motor will not have to be cooled forcibly. If the electric motor does not have to be cooled forcibly, there is no need to provide a cooling fan in the swing arm with no leeway in installation space and the structure for cooing the electric motor can be simplified.

The present inventor thus considered increasing the rated output of the electric motor to enable adequate acceleration to be performed during acceleration of the electric vehicle even at an output no more than the rated output. This is because when the output of the electric motor is no more than the rated output, the electric current that flows through the coil of the electric motor is low and the heat generation amount of the electric motor is low. A state in which the heat generation amount of the electric motor is low can thereby be maintained constantly so that the electric motor does not have to be cooled forcibly and consequently, the cooling mechanism for the electric motor can be simplified.

However, in order to exhibit adequate traveling performance even when the output of the electric motor is no more than the rated output, the rated output of the electric motor must be made extremely large. As the electric motor is increased in size to increase the rated output of the electric motor, the electric motor increases in weight. As the weight of the electric motor increases, the swing arm that houses the electric motor increases in weight. The rear wheel mounted to the swing arm thus degrades in followability with respect to a road surface (road surface followability). When the rear wheel is low in followability with respect to the road surface, the rear wheel cannot swing around a pivot shaft so as to follow changes in unevenness of the road surface. Shaking of the vehicle body thus causes an uncomfortable sensation and the electric vehicle becomes poor in riding comfort.

The present inventor thus carried out further diligent research and arrived at an arrangement, which, by use of a compact electric motor of low rated output for reduction in weight of a swing arm, can realize adequate acceleration performance without forced cooling and can yet apply a large torque to a rear wheel. Specifically, the inventor arrived at an arrangement in which a torque of a rotor of an electric motor is amplified via a two-stage speed reducer and then transmitted to a rear wheel. The two-stage speed reducer includes an input gear rotated by the rotor of the electric motor, an output gear connected to the rear wheel, and an intermediate gear meshed with the above gears. The intermediate gear includes a first gear part meshed with the input gear and a second gear part aligned coaxial to the first gear part and formed integral to the first gear part. With this arrangement, even with a compact electric motor of low torque, the torque of the electric motor is amplified greatly by the two-stage speed reducer and the rear wheel can be driven with an adequate torque.

However, to install such a two-stage speed reducer, a swing arm must be made wide in a vehicle right-left direction (width direction) because the first and second gear parts are aligned in the vehicle right-left direction, etc.
When the swing arm, which is positioned at a height close to the road surface, is made wide in the vehicle right-left direction, a maximum value of an angle (maximum bank angle) by which the electric vehicle can be tilted to make a right turn or left turn decreases. When the maximum bank angle is small, a turning radius during turning of the electric vehicle must be increased and this is unfavorable from a standpoint of operability improvement. It is thus preferable to avoid making the swing arm wide in the vehicle right-left direction.

Thus, an object of the present invention is to provide an electric vehicle with which an adequate torque can be applied to a rear wheel without making an electric motor large, a structure for cooling the electric motor can be simplified, followability of the rear wheel with respect to a road surface can be improved, and yet a large maximum bank angle can be secured.

To achieve the above object, a first aspect of the present invention provides an electric vehicle (1, 1A) including an electric motor (5, 5A) in turn including a stator (82), a rotor (81) facing the stator, and a motor shaft (85) fixed to the rotor, an intermediate shaft (141) disposed adjacent to the motor shaft, an axle (143) disposed adjacent to the intermediate shaft, a speed reduction mechanism (131) in turn including an input gear (140) disposed on the motor shaft, an intermediate gear (142) disposed on the intermediate shaft and meshed with the input gear, and an output gear (144) disposed on the axle and meshed with the intermediate gear, a motor case (67) housing the electric motor and connected to a vehicle body frame (2) in a manner enabling swinging around a pivot shaft (51, 52), a gear case (132, 132A) fixed to the motor case, housing the speed reduction mechanism, and from which the axle projects outward, and a rear wheel (4) in turn including a wheel member (148) connected to the axle and a tire (149) mounted to the wheel member. At least a part of the intermediate gear is disposed at a position overlapping with the stator in a side view. A part of the intermediate gear is disposed to overlap in position in a vehicle right-left direction (Y1) with the wheel member. The intermediate shaft is disposed further forward than the axle. The motor shaft is disposed further forward than the intermediate shaft. In a side view, a part of the stator is disposed further forward than the wheel member.

Although in this section, alphanumeric characters in parentheses represent reference signs of corresponding components respectively, in the embodiments described later, the invention is not limited by these reference signs.
With the present arrangement, an adequate torque can be applied to the rear wheel without making the electric motor large, a structure for cooling the electric motor can be simplified, followability of the rear wheel with respect to a road surface can be improved, and yet a large maximum bank angle can be secured. More specifically, the speed reduction mechanism can perform speed reduction in the two stages of speed reduction between the input gear and the intermediate gear and speed reduction between the intermediate gear and the output gear. A large speed reduction ratio can thereby be realized in the speed reduction mechanism and thus an amount of amplification of the torque of the electric motor can be increased. An adequate torque can thus be applied from the electric motor to the rear wheel without making the electric motor large.

The electric motor can thus be made compact because an adequate torque can be transmitted from the electric motor to the rear wheel without making the electric motor large. A compact electric motor is low in heat generation amount and in addition, the torque is greatly amplified by the speed reduction mechanism. That is, the present arrangement is not one in which the output of a large electric motor is used to apply a large torque to the rear wheel and the output of the large electric motor is transmitted to the rear wheel without transmission through a speed reduction mechanism. Thus, in comparison to a case of using a large electric motor without using the speed reduction mechanism, the output of the electric motor required for the electric vehicle to attain the same acceleration can be lessened in the case of using the speed reduction mechanism and the compact electric motor. Heat generation by the electric motor can thus also be suppressed. A cooling fan for forcibly cooling the electric motor is thus unnecessary and the electric motor can be cooled adequately by natural cooling of the electric motor by a traveling wind of the electric vehicle. The arrangement for cooling the electric motor can thereby be simplified.

Also, the stator of the electric motor is disposed at a position overlapping with at least a part of the intermediate gear in a side view, the motor shaft is disposed further forward than the intermediate shaft, and a part of the stator is disposed further forward than the wheel member in a side view. The electric motor, which is a heavy component, can thereby be disposed toward the front and near the pivot shaft. Also, the electric motor can be made small in moment of inertia about the pivot shaft during traveling of the electric vehicle because a compact electric motor that is lightweight can be used. Consequently, the rear wheel, which swings around the pivot shaft together with the electric motor, can be improved in followability with respect to the road surface.

Also, with the arrangement of Patent Document 1, only a single-stage speed reduction by the two gears of the input gear and the output gear is performed and thus to obtain a large speed reduction ratio, an output gear of large diameter is necessary and thus an interval between the input gear and the output gear must be made wide. In contrast, with the arrangement of the present invention, two-stage speed reduction by three gears is performed and thus the interval between the input gear and the output gear does not have to be made wide to obtain a large speed reduction ratio. The three gears can thus be disposed at narrow intervals. A distance between centers of the electric motor and the rear wheel can thus be shortened and the rear wheel can be disposed further toward the front and nearer the pivot shaft. The rear wheel can thereby made small in moment of inertia about the pivot shaft during traveling of the electric vehicle. Consequently, the rear wheel can be further improved in followability with respect to the road surface.

Further, the position in the vehicle right-left direction of a part of the intermediate gear is overlapped with the position of the wheel member. A length in the vehicle right-left direction (lateral width) that the rear wheel and the intermediate shaft occupy as a whole can thereby be shortened. The rear wheel and the intermediate shaft, which are disposed at positions of comparatively low height from the road surface, can thus be configured to be short in lateral width as a whole, and thus a maximum value of an angle by which the electric vehicle can be tilted in the vehicle right-left direction to make a turn (maximum bank angle) can be made large.

A second aspect of the present invention provides the electric vehicle according to the first aspect where, in a side view, the speed reduction mechanism is positioned inside a region (F1) surrounded by an outer peripheral surface of the wheel member and a part of the speed reduction mechanism is disposed inside a region (F3) surrounded by the stator.

By this arrangement, it becomes possible to dispose more parts of the speed reduction mechanism inside the wheel member and a length that the wheel member, the speed reduction mechanism, and the electric motor occupy as a whole in the vehicle right-left direction can be shortened. The swing unit is thereby made less likely to contact the road surface when the electric vehicle is tilted to make a turn and the maximum bank angle can thus be increased.

A third aspect of the present invention provides the electric vehicle according to the first or second aspect where, in a side view, outer diameters of the input gear, intermediate gear, and output gear of the speed reduction mechanism are all made smaller than an outer diameter of the electric motor.

By this arrangement, it becomes possible to dispose the speed reduction mechanism inside the wheel member more reliably and the length that the wheel member, the speed reduction mechanism, and the electric motor occupy as a whole in the vehicle right-left direction can be shortened. The swing unit is thereby made less likely to contact the road surface when the electric vehicle is tilted to make a turn and the maximum bank angle can thus be increased.

A fourth aspect of the present invention provides the electric vehicle according to any one of the first to third aspects where the intermediate shaft is disposed below the motor shaft and the axle.
By this arrangement, the respective gears can be disposed across a wider range inside the wheel member while keeping the speed reduction mechanism within the wheel member in a side view. The outer diameters of the respective gears can thereby be increased. Consequently, the speed reduction ratio of the speed reduction mechanism can be increased.

A fifth aspect of the present invention provides the electric vehicle according to any one of the first to fourth aspects where, in the gear case, a lubricating oil supply port (160) is disposed at a position to the rear of the electric motor.

By enabling the electric motor to be disposed toward the front as described above, the lubricating oil supply port can be disposed at a rear end part of the gear case. At the rear end part of the gear case, obstructing parts are few and the lubricating oil supply port can thus be operated to open and close readily by a hand. Also, a height position of the lubricating oil supply port can be set freely and thus an amount of lubricating oil in the gear case can be predefined readily by the positioning of the lubricating oil supply port. Also, a lubricating oil pouring work can be performed without removing the motor case.

A sixth aspect of the present invention provides the electric vehicle according to the fifth aspect where the lubricating oil supply port is disposed above a lower end of the speed reduction mechanism.

By this arrangement, the lubricating oil can be scooped up inside the gear case by at least one of the gears and the lubricating oil can thus be supplied reliably to the respective gears of the speed reduction mechanism. Also, an optimum height (oil level) of the lubricating oil can be realized. The oil level can thereby be set to maximize a lubrication effect of the lubricating oil and minimize drive loss of the speed reduction mechanism due to viscous drag of the lubricating oil.

A seventh aspect of the present invention provides the electric vehicle according to any one of the first to sixth aspects where the gear case is provided with a lubricating oil discharge port (163) disposed outside the motor case in a side view.

With this arrangement, the lubricating oil discharge port is disposed outside the motor case in a side view and thus the lubricating oil discharge port can be operated readily by a hand and a lubricating oil discharge work can be performed readily.

An eighth aspect of the present invention provides the electric vehicle according to any one of the first to seventh aspects further including a first breather hose (168) connected to the motor case and a second breather hose (170) connected to the gear case and where the first breather hose and the second breather hose extend rearward from connection parts (75b, 135c) with respect to the corresponding cases and are held at the same position where these breather hoses line from side to side, by a holding member (171).

With this arrangement, a pressure inside the gear case and a pressure inside a motor case can be maintained at atmospheric pressure by the first and second breather hoses. Also, the respective breather hoses are held at the same position and thus the respective breather hoses can be mounted readily at the same time and a work of mounting the respective breather hoses is easy.

A ninth aspect of the present invention provides the electric vehicle according to any one of the first to eighth aspects further including a stand member (177) that has a foothold part (183) for setting a foot, is mounted to the motor case, and can be displaced to a grounded position of being grounded to a road surface (A1) and to a separated position separated from the road surface, and where when the stand member is at the separated position, the foothold part is disposed to overlap with the electric motor in a side view, the electric motor is disposed at the right of the rear wheel, and the foothold part is disposed at the left of the rear wheel.

With this arrangement, the foothold part in the state in which the stand member is at the separated position is disposed to overlap in a side view with the electric motor that is disposed toward the front and near the pivot shaft. The foothold part is thus also positioned toward the front and a driver in a state of standing on a road surface while holding a handle, etc., of the electric vehicle can set his/her foot readily on the foothold part. The stand member can thus be improved in operability. Moreover, the electric motor and the foothold part are disposed at the right and left so as to sandwich the rear wheel, and thus amounts of protrusion of parts in the vehicle right-left direction from the rear wheel can be reduced. Consequently, the maximum bank angle can be increased.

A tenth aspect of the present invention provides the electric vehicle according to any one of the first to eighth aspects further including a stand member (177) that has a foothold part (183) for setting a foot, is mounted to the vehicle body frame, and can be displaced to a grounded position of being grounded to a road surface (A1) and to a separated position separated from the road surface, and where the electric motor and the foothold part are disposed at the left of the rear wheel, and when the stand member is at the separated position, the foothold part is disposed further forward than the electric motor in a side view.

By this arrangement, the foothold part in the state in which the stand member is at the separated position can be disposed toward the front. The driver in a state of standing on a road surface while holding the handle, etc., of the electric vehicle can thus set his/her foot readily on the foothold part. The stand member can thus be improved in operability.

FIG. 1 is a left side view of an electric vehicle according to a first embodiment of the present invention. FIG. 2 is a left side view showing a state in which some parts, such as a vehicle body cover of the electric vehicle, have been removed. FIG. 3 is an enlarged view showing a periphery of the battery shown in FIG. 2. FIG. 4 is a perspective view showing a connecting mechanism and a front end part of a swing unit. FIG. 5 is a partially sectional view of the connecting mechanism and the front end part of the swing unit and shows a state in which the connecting mechanism and the front end part of the swing unit are viewed from above. FIG. 6 is a right side view of a rear part of the electric vehicle. FIG. 7 is an exploded perspective view of the swing unit and shows a state in which the swing unit is viewed obliquely from a rear right side. FIG. 8 is a right side view of the swing unit in a partially exploded state. FIG. 9 is a partially sectional view of the swing unit and a rear wheel and shows a state in which the swing unit and the rear wheel are viewed from above. FIG. 10A is a right side view of the swing unit. FIG. 10B is a right side view of main parts of a periphery of a first stator. FIG. 11 is a sectional view of peripheries of an electric motor and a speed reduction mechanism of the swing unit and shows a state in which a section plane passing through central axes of respective gears of the speed reduction mechanism is viewed from above. FIG. 12 is a sectional view of a second stator and shows a section of the second stator sectioned along a circumferential direction. FIG. 13 is an exploded perspective view of a stator driving device and shows a state in which the stator driving device is viewed obliquely from the rear. FIG. 14A is an illustrative view of main parts for describing a change of output characteristics of the electric motor in accordance with displacement of the second stator. FIG. 14B is an illustrative view of main parts for describing a change of output characteristics of the electric motor in accordance with displacement of the second stator. FIG. 15 is a left side view of main parts of the electric vehicle with illustration of a part of the swing unit being omitted. FIG. 16 is a partially sectional view of an arrangement of main parts of a periphery of a gear case and shows a state in which the gear case is viewed from the left. FIG. 17 is a left side view of the swing unit with a part near a rear end being broken away. FIG. 18A is a left side view of a periphery of the rear wheel. FIG. 18B is a right side view of a periphery of the rear wheel. FIG. 19A is a left side view of the periphery of the rear wheel and shows a state in which a rear fender is removed. FIG. 19B is a right side view of the periphery of the rear wheel and shows a state in which the rear fender is removed. FIG. 20 is a left side view of main parts of an electric vehicle according to a second embodiment of the present invention.

<First Embodiment>
A first embodiment of the present invention shall now be described in detail with reference to the drawings.
FIG. 1 is a left side view of an electric vehicle 1 according to the first embodiment of the present invention. In the present embodiment, the electric vehicle 1 is a scooter. The electric vehicle 1 can travel with freight being placed on its front part and on its rear part and is suitable for use as a freight vehicle.

Each of front, rear, up, down, right, and left directions mentioned in the following description is based on a point of view of a driver when he/she is facing forward with the electric vehicle 1 being in a basic posture corresponding to a state of traveling straight on a horizontal plane. A structure of the electric vehicle 1 shall be described based on the electric vehicle 1 being in a state of standing vertically with a front wheel 3 and a rear wheel 4 grounded on a road surface A1 and without the driver riding thereon.

The electric vehicle 1 includes a vehicle body frame 2, the front wheel 3, the rear wheel 4, an electric motor 5, a battery 6, and a vehicle body cover 7. In the electric vehicle 1, the electric motor 5 is driven by electric power supplied from the battery 6 to the electric motor 5, and the rear wheel 4 is driven by an output of the electric motor 5. The entire structure of the electric vehicle 1 shall now be described in order from a forward part of a vehicle body.

FIG. 2 is a left side view of a state in which some parts, such as the vehicle body cover 7 of the electric vehicle 1, have been removed. The electric vehicle 1 has a head tube 8 disposed at a front upper part of the electric vehicle 1. A steering shaft 9 is rotatably inserted in the head tube 8. A right-and-left pair of front forks 10 are mounted to a lower end part of the steering shaft 9. The front wheel 3 is mounted to the front forks 10.

A handle 11 is mounted to an upper end part of the steering shaft 9. A driver can rotate the steering shaft 9, the front forks 10, and the front wheel 3 around an axis of the steering shaft 9 by operating the handle 11.
Grips 12 are disposed at right and left end parts of the handle 11, respectively (only the left grip is shown in the figure). The right grip serves as a throttle grip. The driver can adjust an output produced by the electric motor 5 by rotating the throttle grip.

As shown in FIG. 1, a meter 13 is disposed near a center of the handle 11. A loading platform 14 is disposed below the meter 13. The loading platform 14 is fixed to the head tube 8. A load of freight piled on the loading platform 14 acts chiefly on the front wheel 3 via the head tube 8, the steering shaft 9, etc. A head lamp 15 is fixed to a lower part of the loading platform 14.

As shown in FIG. 2, the electric vehicle 1 includes the vehicle body frame 2 extending rearward from the head tube 8. The vehicle body frame 2 is formed using a steel-made pipe member or the like. The vehicle body frame 2 includes a down tube 19 and frame main bodies 20 disposed at the rear of the down tube 19. The down tube 19 extends obliquely downward to the rear from a lower part of the head tube 8. In a side view, each frame main body 20 extends rearward from a lower end part of the down tube 19 and an intermediate part thereof in a vehicle front-rear direction X1 is formed to an S-like shape.

A right-left pair of the frame main bodies 20 are provided. Each frame main body 20 includes a first frame part 21, a second frame part 22, a third frame part 23, and a fourth frame part 24. The first frame part 21 extends substantially straight to the rear from the lower end part of the down tube 19 and is slightly inclined obliquely upward toward the rear.

The second frame part 22 is formed to an S-like shape in a side view. The second frame part 22 includes a lower end part 22a, a middle part 22b, and an upper end part 22c. The lower end part 22a of the second frame part 22 has a curved shape and is connected to a rear end part of the first frame part 21. The middle part 22b of the second frame part 22 extends straight and obliquely upward toward the rear from the lower end part 22a. In a side view, an inclination angle of the middle part 22b with respect to the first frame part 21 is, for example, approximately 45 degrees. The upper end part 22c of the second frame part 22 has a curved shape and is connected to the middle part 22b.

The third frame part 23 extends straight from the upper end part 22c and is inclined slightly obliquely upward toward the rear. The fourth frame part 24 extends toward the rear from the middle part 22b of the second frame part 22, is curved obliquely upward toward the rear at an on-the-way position, and is connected to a middle part of the third frame part 23.

As shown in FIG. 1, the electric vehicle 1 includes the vehicle body cover 7 that is mounted to the vehicle body frame 2. The vehicle body cover 7 includes a front cover 25 that covers the head tube 8, a lower cover 26 extending to the rear from a lower part of the front cover 25, and a rear cover 27 disposed at the rear of the front cover 25.

The front cover 25 surrounds the head tube 8 and a part of the steering shaft 9, and surrounds the down tube 19. The lower cover 26 extends to the rear from a lower part 25a of the front cover 25 and covers the first frame part 21 and the lower end part 22a of the second frame part 22 from below and from both the right and left sides. A feet-putting part 28 is disposed at an upper end part of the lower cover 26. The feet-putting part 28 is used for a driver to put his/her feet thereon and has a substantially flat shape.

As a whole, the rear cover 27 is shaped so as to extend obliquely upward toward the rear from a rear part 26a of the lower cover 26. The rear cover 27 covers a part of the second frame part 22 excluding the lower end part 22a from the front side and from both the right and left sides. Also, the rear cover 27 covers the third frame part 23 and the fourth frame part 24 from the front side and from both the right and left sides.

A seat 29 is disposed above the rear cover 27. The feet of a driver sitting on the seat 29 are put on the feet-putting part 28 while the electric vehicle 1 is traveling. In the front-rear direction X1, the feet-putting part 28 is disposed between a rear surface 25b of the front cover 25 and a front end part 29a of the seat 29. Also, the seat 29 is disposed above the second frame part 22, above a part of the third frame part 23, and above a part of the fourth frame part 24. A space surrounded by the seat 29 and the rear cover 27 defines a housing space S1.

As shown in FIG. 2, the seat 29 is supported by a first bracket 31 and a support bracket 37. The first bracket 31 is mounted to the middle part 22b of the second frame part 22. The first bracket 31 extends upward from the middle part 22b. A hinge part 38 is disposed at an upper end part of the first bracket 31. The seat 29 is supported by the first bracket 31 via the hinge part 38. The first bracket 31 supports the seat 29 from below. The seat 29 can be rotated around the hinge part 38. The housing space S1 can be opened upward by rotating the seat 29 around the hinge part 38. The hinge part 38 may be omitted and the seat 29 may be fixed directly to the first bracket 31.

A rear part 29b of the seat 29 is supported by the support bracket 37. The support bracket 37 is fixed to the third frame part 23 of the vehicle body frame 2 and has a shape that projects upward from the third frame part 23.
A battery 6 serving as a power source of the electric motor 5 is disposed in the housing space S1 below the seat 29. The battery 6 is disposed between the right-and-left pair of second frame parts 22. The battery 6 is a rechargeable secondary battery. The battery 6 is formed to a substantially rectangular shape in a side view and its length (height) in an up-down direction Z1 of the vehicle is made longer than its length (width) in the front-rear direction X1. The battery 6 is disposed in an orientation of inclining upward toward the rear and is supported by the vehicle body frame 2. An upper part 6a of the battery 6 is disposed between the first bracket 31 and the support bracket 37.

FIG. 3 is an enlarged view showing a periphery of the battery 6 shown in FIG. 2. The battery 6 is supported by the vehicle body frame 2 via a battery supporting device 39. The battery supporting device 39 includes first to fifth brackets 31 to 35 and a subframe 36. A front surface 6b of the battery 6 is supported by the first bracket 31 and the second bracket 32. A rear surface 6c of the battery 6 is supported by the third bracket 33 and the fourth bracket 34. A lower part 6d of the battery 6 is supported by the fifth bracket 35.

The first bracket 31 is in contact with a central part in the up-down direction Z1 of the front surface 6b of the battery 6. The second bracket 32 includes an upper second bracket 41 and a lower second bracket 42. The upper second bracket 41 extends from the upper end part 22c of the second frame part 22 toward the front of the battery 6 and comes into contact with the front surface 6b at the upper part 6a of the battery 6. The lower second bracket 42 extends from the middle part 22b of the second frame part 22 toward the front of the battery 6 and comes into contact with the front surface 6b at the lower part 6d of the battery 6.

The third bracket 33 extends from the third frame part 23 toward the battery 6 and comes into contact with the rear surface 6c at the upper part 6a of the battery 6.
The fourth bracket 34 is in contact with the rear surface 6c at the lower part 6d of the battery 6. The fourth bracket 34 is supported by the subframe 36. The subframe 36 is formed by use of a pipe member and is made capable of receiving a load of the battery 6. The subframe 36 includes a subframe main body 43 and an arm part 44. The subframe main body 43 extends obliquely downward toward the rear from a lower end of the middle part 22b of the second frame part 22. The fourth bracket 34 is fixed to a rear end part of the subframe main body 43. The arm part 44 extends obliquely downward toward the front from the subframe main body 43 and is fixed to the lower end part 22a of the second frame part 22.

The fifth bracket 35 is disposed at an upper side of the subframe main body 43 and is fixed to the subframe main body 43.
As shown in FIG. 1, a loading platform 45 is disposed behind the seat 29. The loading platform 45 is disposed at an upper side of the third frame part 23 and is supported by this third frame part 23. Pieces of freight can be placed on an upper side of the loading platform 45. A load of the freight placed on the loading platform 45 is received chiefly by the rear wheel 4.

The loading platform 14, the battery 6 that is a heavy component, and the loading platform 45 are thus aligned in the front-rear direction X1. The electric vehicle 1 can thus be balanced evenly in load in the front-rear direction X1 when pieces of freight are placed on the loading platform 14 and the loading platform 45. High operability of the electric vehicle 1 can thus be maintained even when pieces of freight are placed on the loading platform 14 and the loading platform 45.

FIG. 4 is a perspective view of a connecting mechanism 46 and a front end part of a swing unit 47. The electric vehicle 1 includes the connecting mechanism 46 and the swing unit 47 that is swingably connected to the vehicle body frame 2 via the connecting mechanism 46.

The connecting mechanism 46 includes fixed parts 48R and 48L that are fixed to the right-and-left pair of fourth frame parts 24 (24L and 24R), movable parts 49L and 49R, the first pivot shaft 51, and the second pivot shafts 52L and 52R. Each of the fixed parts 48L and 48R is a plate member formed to a downwardly open U-like shape.

FIG. 5 is a partially sectional view of the connecting mechanism 46 and the front end part of the swing unit 47 and shows a state in which the connecting mechanism 46 and the front end part of the swing unit 47 are viewed from above. The left fixed part 48L includes a right-and-left pair of plate parts 53L and 53L, and the right fixed part 48R includes a right-and-left pair of plate parts 53R and 53R.

Through-holes 54 are formed in the plate parts 53L and 53L of the fixed part 48L. A plate-like movable part 55L is disposed between the plate parts 53L and 53L. A hole is formed in a front part of the movable part 55L, and a reinforcement pipe 56L is fixed to this hole. A damper 57L and the second pivot shaft 52L are inserted in the reinforcement pipe 56L. The damper 57L is formed by use of a cylindrical elastic member made of rubber, etc. The second pivot shaft 52 is a shaft part of a bolt member 58L and passes through the damper 57L and the respective through-holes 54 of the plate parts 53L and 53L. A nut 59L is fastened to the bolt member 58.

Through-holes 54 are formed in the plate parts 53R and 53R of the fixed part 48R. A plate-like movable part 55R is disposed between the plate parts 53R and 53R. A hole is formed in a front part of the movable part 55R, and a reinforcement pipe 56R is fixed to this hole. A damper 57R and the second pivot shaft 52R are inserted in the reinforcement pipe 56R. The damper 57R is formed by use of a cylindrical elastic member made of rubber, etc. The second pivot shaft 52R is a shaft part of a bolt member 58R and passes through the damper 57R and the through-holes 54 of the plate parts 53R and 53R. The second pivot shafts 52L and 52R are disposed coaxially. A nut 59R is fastened to the bolt member 58R.

Through-holes 60R and 60L are formed in rear parts of the movable parts 55R and 55L, respectively. The first pivot shaft 51 is inserted through the through-holes 60R and 60L. The first pivot shaft 51 is a shaft part of the bolt member 61. A nut 62 is fastened to the bolt member 61. A cylindrical collar 63 is fitted onto the first pivot shaft 51. The collar 63 is disposed between the movable parts 55R and 55L. A reinforcement bar 64 is disposed adjacent to the collar 63 between the movable parts 55R and 55L. Connection rigidity between the movable parts 55R and 55L is secured by the collar 63 and the reinforcement bar 64. Also, a pair of bearings 65 and 66 are mounted to an outer periphery of the collar 63. The bearings 65 and 66 are mounted to a front end part 47a of the swing unit 47.

According to this structure, the movable parts 55L and 55R can swing around the second pivot shafts 52L and 52R, respectively, within a range in which the dampers 57L and 57R are elastically deformable. That is, the swing unit 47 can swing around each of the second pivot shafts 52L and 52R within a range in which the dampers 57L and 57R are elastically deformable. Also, the swing unit 47 can swing around the first pivot shaft 51. In the present embodiment, an angular range in which the swing unit 47 can swing around the first pivot shaft 51 may be ten-odd degrees, and the angular range in which the swing unit 47 can swing around the second pivot shafts 52 may be several degrees.

As shown in FIG. 4, the swing unit 47 includes a motor case 67 and inclined parts 68R and 68L formed at a front end part 67a of the motor case 67. The front end part 47a of the swing unit 47 includes the front end part 67a of the motor case 67 and the inclined parts 68R and 68L. The inclined parts 68R and 68L are aligned in a right-left direction Y1.

Each of the inclined parts 68R and 68L extends obliquely upward toward the front from the motor case 67. A through-hole 68a is formed in a front end of each of the inclined parts 68R and 68L. As shown in FIG. 5, corresponding bearings 65 and 66 are mounted to the respective through-holes 68a. The inclined parts 68R and 68L (swing unit 47) are thereby enabled to swing around the first pivot shaft 51.

FIG. 6 is a right side view of a rear part of the electric vehicle 1. The swing unit 47 is disposed at the right of the rear wheel 4. A rear part 47b of the swing unit 47 is connected to the third frame part 23 via a shock absorber 69. Shock occurring when the swing unit 47 swings can thus be attenuated and absorbed by the shock absorber 69. In a side view, the swing unit 47 is disposed below the third frame part 23. The motor case 67 of the swing unit 47 is arranged so that, in a side view, its length in the front-rear direction X1 is longer than its length in the up-down direction Z1.

FIG. 7 is an exploded perspective view of the swing unit 47 and shows a state in which the swing unit 47 is viewed obliquely from a right rear side. The motor case 67 of the swing unit 47 includes a motor case main body 71, a connecting member 72 fixed to a front end part of the motor case main body 71, and a cover 73 covering a right side surface of the motor case main body 71.

The motor case main body 71 has a front end part 67a extending in the right-left direction Y1 and is formed to a shape that extends rearward from a right part of the front end part 67a.
The connecting member 72 is disposed at the left of a front end part of the motor case main body 71. The connecting member 72 and the front end part of the motor case main body 71 are fixed using a plurality of screw members 74. The inclined part 68L is formed integral to the connecting member 72. The inclined part 68R is formed integral to the front end part of the motor case main body 71. The front end part 67a of the motor case 67 is formed by the connecting member 72 and the front end part of the motor case main body 71.

The motor case main body 71 includes a side wall 75 extending in the front-rear direction X1 and a tubular peripheral wall 76 extending to the right from an outer peripheral edge part of the side wall 75. A motor housing space S2, capable of housing the electric motor 5, is formed by the side wall 75 and the peripheral wall 76.

FIG. 8 is a right side view of the swing unit 47 in a partially exploded state. The peripheral wall 76 includes a first part 76a to a sixth part 76f. The first part 76a extends obliquely upward toward the rear. The second part 76b extends rearward from the first part 76a and is formed to a curved shape that is upwardly convex. The third part 76c is formed to a semicircular shape that is convex toward the rear. The fourth part 76d extends obliquely upward toward the front from a lower end of the third part 76c. The fifth part 76e extends straight forward from the fourth part 76d. The sixth part 76f extends obliquely upward toward the front from the fifth part 76e and is connected to the first part 76a.

As shown in FIG. 7, the cover 73 is disposed at the right of the peripheral wall 76 and covers the motor housing space S2. The cover 73 is fixed using a plurality of screw members 77 to a right end surface of the peripheral wall 76. An unillustrated gasket, etc., is disposed between the peripheral wall 76 and the cover 73.

The swing unit 47 includes a controller 78, the electric motor 5, and a stator driving device 79, which are disposed inside the motor housing space S2.
The controller 78 has an arrangement where an inverter circuit or other driver circuit, a control circuit that controls the driver circuit, etc., are disposed inside a case 78a formed using a synthetic resin, etc. The inverter circuit is a circuit that converts DC power from the battery 6 (see FIG. 2) to AC power and supplies the AC power to the electric motor 5. The control circuit includes a CPU, a RAM, and a ROM and controls the inverter circuit so that the electric motor 5 generates an output that is in accordance with an amount of operation of a throttle by the driver.

As shown in FIG. 8, the case 78a of the controller 78 is formed to a substantially rectangular shape in a side view. The controller 78 is disposed at a front part of the motor housing space S2 and is sandwiched by the second part 76b and the fifth part 76e of the peripheral wall 76.

That is, the controller 78 is disposed at a position that is closer to the first pivot shaft 51 than the electric motor 5. An acceleration that acts on the controller 78 when the swing unit 47 swings around the first pivot shaft 51 is thereby reduced. An external force acting on the controller 78 is thereby reduced and the controller 78 can thus be made high in durability.

The electric motor 5 is disposed at the rear of the controller 78. The electric motor 5 is surrounded by the second part 76b, the third part 76c, and the fourth part 76d of the peripheral wall 76. A length (height) in the up-down direction Z1 of the motor housing space S2 is made longer at a region in which the electric motor 5 is disposed than at a region in which the controller 78 is disposed. A space in which the controller 78 is housed can thereby be made small while making the electric motor 5 large. The electric motor 5 can thus be made large without making the swing unit 47 large.

As shown in FIG. 7, the electric motor 5 includes a rotor 81 and a stator 82 that faces the rotor 81. In the present embodiment, the electric motor 5 is an eight-pole, twelve-slot brushless motor. The electric motor 5 is an axial gap motor and a gap in an axial direction (right-left direction Y1) of the electric motor 5 is provided between the rotor 81 and stator 82. The rotor 81 is disposed at the right of the stator 82.

The rotor 81 includes a rotor core 83 formed to a disk-like shape and rotor magnets 84 fixed to the rotor core 83. The rotor core 83 includes a rotor core main body 83a fixed to a motor shaft 85 and an extended part 83b spreading radially outward from a right end part of the rotor core main body 83a. The rotor core main body 83a is connected to a right end part of the motor shaft 85 by spline coupling, etc., and is integrally rotatable with the motor shaft 85.

The rotor magnets 84 are fixed to a left side surface of the extended part 83b that faces the stator 82. A plurality of the rotor magnets 84 are provided and are disposed at equal intervals along a circumferential direction of the rotor core 83. The rotor magnets 84 are disposed so that N and S poles alternate along the circumferential direction of the rotor core 83. In the present embodiment, eight rotor magnets 84 are provided.

FIG. 9 is a partially sectional view of the swing unit 47 and the rear wheel 4 and shows a state in which the swing unit 47 and the rear wheel 4 are viewed from above. Hereinafter, parts in a drawing may be indicated by alternate long and two short dashed lines. The rotor 81 is disposed adjacent to the cover 73. The cover 73 includes a first part 73a that is aligned with the controller 78 in the right-left direction Y1 and a second part 73b that is disposed at the rear of the first part 73a. The second part 73b is positioned further to the right than the first part 73a and is aligned with the rotor 81 in the right-left direction Y1. By this arrangement, a width of the motor housing space S2 in the right-left direction Y1 is made narrower at a region in which the controller 78 is disposed than at a region in which the electric motor 5 is disposed.

The width of the motor housing space S2 at a periphery of the controller 78 can thus be made narrow and the swing unit 47 can thus be made compact. As a result of being able to make the width of the motor housing space S2 narrow, a maximum angle (maximum bank angle) by which the electric vehicle 1 can be tilted to make a turn can be made large and turning performance of the electric vehicle 1 can thus be improved. The rotor 81 is fixed to the motor shaft 85 as an output shaft of the electric motor 5.

As shown in FIG. 7, the stator 82 is disposed at the left of the rotor 81. The stator 82 is formed to a tubular shape that surrounds the motor shaft 85. The stator 82 includes a first stator 86 and a second stator 87 that are aligned in an axial direction of the electric motor 5. The first stator 86 is disposed at the left of the rotor 81 and is fixed by use of screw members to the side wall 75 of the motor case main body 71. The second stator 87 is disposed at the left of the first stator 86 and is made displaceable in a circumferential direction of the stator 82 with respect to the first stator 86. Paths of magnetic flux generated by the stator 82 can thereby be changed to enable a magnetic force acting between the stator 82 and the rotor 81 to be changed.

FIG. 10A is a right side view of the swing unit 47. The first stator 86 includes first tees 88, coils 89, and a first synthetic resin member 90. The first tees 88 are columnar parts extending in the axial direction of the electric motor 5. A plurality of the first tees 88 are provided and disposed at equal intervals in a circumferential direction of the stator 82. In the present embodiment, twelve first tees 88 are provided.

The coils 89 are wound around the respective first tees 88. The coils 89 are aligned in an ordered manner in the order of a U-phase coil, V-phase coil, W-phase coil, U-phase coil, V-phase coil, ... along the circumferential direction of the electric motor 5. Among the coils 89, the respective U-phase coils are connected to a U-phase bus bar 91U. Among the coils 89, the respective V-phase coils are connected to a V-phase bus bar 91V. Among the coils 89, the respective W-phase coils are connected to a W-phase bus bar 91W. The bus bars 91U, 91V, and 91W are respectively connected to the controller 78.

In the up-down direction Z1, the respective bus bars 91U, 91V, and 91W are disposed between an upper end part 82c and a lower end part 82d of the stator 82 and disposed between an upper end part 78b and a lower end part 78c of the controller 78. Also, in the front-rear direction X1, the respective bus bars 91U, 91V, and 91W are disposed between the stator 82 and the controller 78. By the respective bus bars 91U, 91V, and 91W being disposed thus, a space between the stator 82 and the controller 78 can be used effectively as an installation space for the respective bus bars 91U, 91V, and 91W. The swing unit 47 can thus be made compact.

FIG. 10B is a right side view of main parts of a periphery of the first stator 86. The first synthetic resin member 90 is molded over the first tees 88 and the respective coils 89. The first stator 86 can thus be handled as a single part during assembly of the swing unit 47 and assembly work of the swing unit 47 is made easy. An outer peripheral surface 90a of the first synthetic resin member 90 includes a first outer peripheral surface 90d and a second outer peripheral surface 90e. The first outer peripheral surface 90d is formed to a circular shape in a side view. The second outer peripheral surface 90e is disposed at the right (in front of the paper surface) of the first peripheral surface 90d. In a side view, the second outer peripheral surface 90e is formed to an uneven shape that protrudes at parts aligned with the coils 89 in radial directions of the first stator 86 and is recessed at parts between the first tees 88.

As shown in FIG. 7, the first synthetic resin member 90 includes flange parts 90b that project outward from the first outer peripheral surface 90d. The flange parts 90b are disposed at a left end part of the first stator 86 and are adjacent to the second stator 87. A plurality of the flange parts 90b are formed along the circumferential direction of the electric motor 5. A screw insertion hole is formed in each flange part 90b and a screw member (not shown) is inserted in the screw insertion hole. Each screw member is threadingly engaged to a threaded hole formed in the side wall 75 of the motor case main body 71. The first stator 86 is thereby fixed to the motor case main body 71.

As shown in FIG. 10B, in a side view, a region surrounded by the first outer peripheral surface 90d and outer peripheral surfaces of the respective flange parts 90b (region surrounded by an outermost peripheral part of the first stator 88) defines a stator interior region F3.
FIG. 11 is a sectional view of peripheries of the electric motor 5 and a speed reduction mechanism 131 of the swing unit 47 and shows a state in which a section plane, passing through central axes of respective gears 140, 142, and 144 of the speed reduction mechanism 131, is viewed from above. The first synthetic resin member 90 has an inner peripheral surface 90c that surrounds the motor shaft 85. A right end part of the inner peripheral surface 90c rotatably supports the rotor core main body 83a via a first bearing 101. By this arrangement, the first bearing 101 rotatably supports a right end part of the motor shaft 85 via the rotor core main body 83a. In the present embodiment, the first bearing 101 and second to eighth bearings 102 to 108 to be described later are ball bearings, respectively.

FIG. 12 is a sectional view of the second stator 87 and shows a section of the second stator 87 sectioned along a circumferential direction. The second stator 87 includes a yoke 93, second tees 94, and a second synthetic resin member 95.

The yoke 93 is a disk-like plate part. The second tees 94 project to the right from a right side surface of the second yoke 93. A plurality of the second tees 94 are provided at equal intervals along the circumferential direction of the electric motor 5. The number of the second tees 94 is the same as the number of the first tees 88. The second synthetic resin member 95 is formed to a circular annular shape and is molded over the second yoke 93 and the respective second tees 94. A right end surface of each second tees 94 is exposed from the second synthetic resin member 95.

As shown in FIG. 11, in the axial direction of the electric motor 5, a length of each second tees 94 is shorter than a length of the first tees 88. A second bearing 102 is mounted to an inner peripheral surface of the second synthetic resin member 95. An inner peripheral part of the second bearing 102 is mounted to a left half part of a cylindrical connecting member 96. A right half part of the connecting member 96 is fixed to the inner peripheral surface 90c of the first synthetic resin member 90. By the above arrangement, the second stator 87 is supported in relatively rotatable manner by the first stator 86 via the second bearing 102 and the connecting member 96.

As show in FIG. 7, the second stator 87 is smaller in diameter than the first stator 86. The stator driving device 79 is provided for changing a position of the second stator 87 in the circumferential direction of the electric motor 5. The stator driving device 79 is disposed obliquely upward in front of the second stator 87.

FIG. 13 is an exploded perspective view of the stator driving device 79 and shows a state in which the stator driving device 79 is viewed obliquely from the rear. The stator driving device 79 includes a drive motor 111, a first gear mechanism 112, a second gear mechanism 113, an output gear 114, and a frame 115.

The drive motor 111 includes a case 116 and an output shaft 117 projecting out to the rear from the case 116.
The first gear mechanism 112 is a speed reduction mechanism that includes a small gear 118 and a large gear 119 of larger diameter than the small gear 118. The small gear 118 is fixed to the output shaft 117. The large gear 119 is disposed at the left of the small gear 118 and is meshed with the small gear 118. A connection hole 119a is formed in the large gear 119.

The second gear mechanism 113 is a worm speed reduction mechanism that includes a worm shaft 120 and a worm wheel 121. A connection part 120a is formed at a front end part of the worm shaft 120. The connection part 120a is fixed to the connection hole 119a. The worm wheel 121 is meshed with the worm shaft 120.

The output gear 114 is, for example, a spur gear. A left half part of the output gear 114 is fixed to a connection hole 121a of the worm wheel 121. The connection hole 121a is formed to a shape matching a shape of an outer peripheral surface of the output gear 114. A right half part of the output gear 114 projects out to the right from the worm wheel 121.

The frame 115 holds the drive motor 111, the first gear mechanism 112, the second gear mechanism 113, and the output gear 114. The frame 115 includes a frame main body 110, a first cover 122, and a second cover 123.
The frame main body 110 is an integrally molded item formed using a synthetic resin, etc. The frame main body 110 includes a first housing part 124 and a second housing part 125. The first housing part 124 is provided for housing the first gear mechanism 112. The first housing part 124 is formed to a box-like shape that is opened at a front side. The first housing part 124 houses the first gear mechanism 112 and the front end part of the worm shaft 120.

The first cover 122 is fixed to a front end part of the first housing part 124. The first cover 122 is formed to a rectangular plate-like shape. The first cover 122 covers the first housing part 124 from the front. The first cover 122 fixes a rear end part of the case 116. A through-hole 122a is formed in the first cover 122 and the output shaft 117 projects out to the rear through the through-hole 122a.

The second housing part 125 is disposed at the rear of the first housing part 124. The second housing part 125 surrounds a rear part of the worm shaft 120 and surrounds an outer periphery of the worm wheel 121. The second cover 123 is fixed to a right side surface of the second housing part 125. The second cover 123 includes a cover part 126 covering a right side surface of the worm wheel 121 and a projecting part 127 that projects rightward from the cover part 126. The projecting part 127 is formed to a cylindrical shape with a closed tip. The right half part of the output gear 114 is housed in the projecting part 127. A notched part 127a is formed in a part of the projecting part 127. The output gear 114 is exposed to a lower side from the notched part 127a.

By the above arrangement, an output rotation of the output shaft 117 of the drive motor 111 is speed-reduced and increased in torque by the first gear mechanism 112 and the second gear mechanism 113 and transmitted to the output gear 114. Meanwhile, a force input into the output gear 114 from the second stator 87, etc., is received by the meshing of the worm wheel 121 and the worm shaft 120 to restrict rotation of the output gear 114. Thus, during stoppage of the drive motor 111, the output gear 114 does not rotate readily even when a force is input from the output gear 114.

As shown in FIG. 8, a central axis 111a of the drive motor 111 is positioned so as to be directed laterally in a side view. In the present embodiment, an inclination of the central axis 111a with respect to the front-rear direction X1 is set to no more than 45 degrees. Consequently, when the swing unit 47 swings around the first pivot axis 51, the drive motor 111 receives a vibration force in a direction substantially orthogonal to the central axis 111a of the drive motor 111. With the vibration force in the direction substantially orthogonal to the central axis 111a of the drive motor 111, deviation of a position of the rotor inside the drive motor 111, etc., due to the vibration force can be suppressed. Consequently, faults of the drive motor 111 can be suppressed more reliably in comparison to a case where the drive motor 111 is positioned so as to be directed vertically (so that the central axis 111a of the drive motor 111 is directed in the up-down direction Z1).

A front part of the drive motor 111 is disposed above the controller 78. The drive motor 111 is adjacent to the second part 76b of the peripheral wall 76 of the motor case main body 71. The first housing part 124 of the frame 115 is disposed between the stator 82 and the controller 78 in the front-rear direction X1.

The output gear 114 is meshed with a tooth part 87a formed on the second stator 87. In the present embodiment, the tooth part 87a is a sector gear that projects outward from the second synthetic resin member 95 of the second stator 87. The second stator 87 is displaced in the circumferential direction of the electric motor 5 in accordance with the rotation of the output gear 114. In the present embodiment, an angular range in which the second stator 87 is displaceable in the circumferential direction of the electric motor 5 is approximately 15 degrees.

A magnetized part 128 is disposed at an outer peripheral part of the second stator 87. A magnetic pattern is formed in the magnetized part 128. Displacement of the magnetized part 128 (second stator 87) is detected by a position sensor 129a. The position sensor 129a is disposed at an upper part of the motor housing space S2 at the left (behind the paper surface of FIG. 8) of the second stator 87. The position sensor 129a is held by a circuit board 129. The circuit board 129 is fixed to the side wall 75 of the motor case main body 71. An output of the position sensor 129a is output via the circuit board 129 to the controller 78. The controller 78 is electrically connected to the drive motor 111. The controller 78 is arranged to control the driving of the drive motor 111 while referencing the position of the second stator 87 detected by the position sensor 129a. The second stator 87 is thereby displaced.

FIG. 14A and FIG. 14B are illustrative views of main parts for describing changes of output characteristics of the electric motor 5 in accordance with displacement of the second stator 87. In FIG. 14A and FIG. 14B, illustration of the coils, etc., is omitted.

By the position control of the second stator 87, the second stator 87 can be displaced between a first position and a second position. When as shown in FIG. 14A, the second stator 87 is positioned at the first position, the respective second tees 94 face the corresponding first tees 88 in the axial direction of the electric motor 5. When as shown in FIG. 14B, the second stator 87 is positioned at the second position, the respective second tees 94 do not face the respective first tees 88 in the axial direction of the electric motor 5.

When as shown in FIG. 14A, the second stator 87 is positioned at the first position, a gap G1 between first and second tees 88 and 89 is small and a magnetic resistance is small. When the electric motor 5 is driven in this state, a strong magnetic flux M1 is generated in the electric motor 5. The magnetic flux M1 passes through the rotor core 83 of the rotor 81, the first tees 88, the second tees 94, and the yoke 93 of the second stator 87. By the generation of the strong magnetic flux M1, the electric motor 5 can generate an output that is low in rotation but high in torque. The electric vehicle 1 is arranged to generate the strong magnetic flux M1 when starting from a stopped state or when climbing a sloping road.

Meanwhile, when as shown in FIG. 14B, the second stator 87 is positioned at the second position, the gap G1 between the first and second tees 88 and 94 is large and the magnetic resistance is large. When the electric motor 5 is driven in this state, a magnetic flux M2 that is weaker than the magnetic flux M1 is generated in the electric motor 5. The magnetic flux M2 is formed in a periphery of the rotor core 83 of the rotor 81 and the first tees 88 and does not pass through the second stator 87. By the generation of the weak magnetic flux M2, the electric motor 5 can generate an output that is low in torque but high in rotation. The electric vehicle 1 is arranged to generate the magnetic flux M2 when traveling at a constant speed on a flat road, etc.

Arrangements are thus made so that the electric motor 5 generates outputs in accordance with traveling states of the electric vehicle 1 by changing the magnetic fluxes M1 and M2 generated in the electric motor 5.

Also, as shown in FIG. 10B, Hall IC sensors or other magnetic pole sensors 130a are disposed adjacent to the stator 82. The magnetic pole sensors 130a are provided respectively in correspondence to the U-phase coils, the V-phase coils, and the W-phase coils. Each magnetic pole sensor 130a is held by a sensor board 130. The sensor board 130 is disposed adjacent to the first synthetic resin member 90. In a side view, the magnetic pole sensors 130a are disposed in slots between mutually adjacent tees. As shown in FIG. 10A, outputs of the respective magnetic pole sensor 130a are arranged to be input into the controller 78. The controller 78 controls electric power supplied to the respective bus bars 91U, 91V, and 91W based on the signals from the respective magnetic pole sensors 130a.

As shown in FIG. 11, the swing unit 47 includes the speed reduction mechanism 131 that transmits the output of the electric motor 5 to the rear wheel 4. The speed reduction mechanism 131 is arranged to reduce the speed of rotation of the motor shaft 85 of the electric motor 5 to amplify the torque from the motor shaft 85 and output it to the rear wheel 4.

The speed reduction mechanism 131 is housed in a gear case 132 fixed to the motor case 67. The gear case 132 is divided in the right-left direction Y1. The gear case 132 includes a first part 132a formed integral to the side wall 75 of the motor case main body 71 and a second part 132b formed using a member separate from the first part 132a.

As a whole, the first part 132a is formed to a shape that is recessed toward the right. The first part 132a includes a right side wall 133 that is continuous with the side wall 75 of the motor case main body 71 and a tubular first peripheral wall 134 extending to the left from an outer peripheral part of the right side wall 133.

The second part 132b is disposed at the left of the first part 132a. As a whole, the second part 132b is formed to a shape that is recessed toward the left.
The second part 132b includes a left side wall 135, a tubular second peripheral wall 136 extending to the right from an outer peripheral part of the left side wall 135, and first and second extended parts 137 and 138 of cylindrical shapes that extend to the left from the left side wall 135.

The second peripheral wall 136 is fixed to the first peripheral wall 134 by use of a plurality of screw members 139 (see FIG. 7). A left end surface of the first peripheral wall 134 and a right end surface of the second peripheral wall 136 are respectively formed as flat surfaces that are abutted against each other. An unillustrated seal member is disposed between the left end surface and the right end surface. A peripheral wall of the gear case 132 is formed by the first peripheral wall 134 and the second peripheral wall 136. A space inside the gear case 132, that is, the space between the first part 132a and the second part 132b is arranged as a gear housing space S3.

The speed reduction mechanism 131 is housed inside the gear housing space S3. The speed reduction mechanism 131 is a two-stage speed reduction arrangement that has three shafts. The speed reduction mechanism 131 includes an input gear 140, an intermediate shaft 141, an intermediate gear 142, and an output gear 144 disposed on an axle 143.

In the present embodiment, the respective gears 140, 142, and 144 are spur gears.
The input gear 140 is disposed integrally on the motor shaft 85. The motor shaft 85 has a function of an output shaft of the electric motor 5 and a function of an input shaft of the speed reduction mechanism 131. An intermediate part of the motor shaft 85 is inserted through a through-hole 145 formed in the side wall 75 of the motor case main body 71 and the first part 132a. A seal member 146 is disposed between the through-hole 145 and the intermediate part of the motor shaft 85. Also, a third bearing 103 is disposed between the through-hole 145 and the intermediate part of the motor shaft 85. The third bearing 103 is housed in the gear housing space S3 at the left of the seal member 146. The right side wall 133 of the gear case 132 has a cylindrical bearing holding part 133a that holds the third bearing 103. The gear case 132 rotatably supports the intermediate part of the motor shaft 85 via the third bearing 103.

The motor shaft 85 extends to the left of the third bearing 103. A fourth bearing 104 is fitted onto a left end part of the motor shaft 85. The fourth bearing 104 is held by a cylindrical bearing holding part 135a formed in the left side wall 135 of the gear case 132. The gear case 132 thus rotatably supports the left end part of the motor shaft 85 via the fourth bearing 104. A diameter (outer diameter) of the third bearing 103 is made greater than a diameter of the fourth bearing 104. Rigidity of support of a right half part of the motor shaft 85, into which the torque from the electric motor 5 is input, can thereby be made high and the swing unit 47 is made compact by making the fourth bearing 104 compact.

The input gear 140 is disposed between the third bearing 103 and the fourth bearing 104. The input gear 140 is disposed near a front end of the gear case 132. The intermediate shaft 141 is disposed rearwardly adjacent to the motor shaft 85 and is aligned parallel to the motor shaft 85. That is, the motor shaft 85 is disposed further forward than the intermediate shaft 141.

A fifth bearing 105 is fitted onto a right end part of the intermediate shaft 141. The fifth bearing 105 is held by a cylindrical bearing holding part 133b formed in the right side wall 133 of the gear case 132. Also, a sixth bearing 106 is fitted onto a left end part of the intermediate shaft 141. The sixth bearing 106 is held by a cylindrical bearing holding part 135b formed in the left side wall 135 of the gear case 132. By the above arrangement, the intermediate shaft 141 is rotatably supported by the gear case 132 via the fifth and sixth bearings 105 and 106. The intermediate shaft 141 is aligned with a part of the second bearing 102 in the right-left direction Y1. The intermediate shaft 141 is disposed further forward than the axle 143.

The intermediate gear 142 is disposed on the intermediate shaft 141. The intermediate gear 142 is arranged to be meshed with the input gear 140 and meshed with the output gear 144. The intermediate gear 142 has a first intermediate gear 142a and a second intermediate gear 142b. The first intermediate gear 142a is fitted onto an outer periphery of the intermediate shaft 141 and fixed to the intermediate shaft 141 by press-fitting, etc. The first intermediate gear 142a is meshed with the input gear 140. The first intermediate gear 142a is formed to be larger in diameter than the input gear 140.

The second intermediate gear 142b is disposed at the right of the first intermediate gear 142a. The second intermediate gear 142b is formed integral to the intermediate shaft 141. The second intermediate gear 142b is formed to be smaller in diameter than the first intermediate gear 142a. The output gear 144 is fixed to the axle 143.

The axle 143 is aligned with the rear end part 82a of the stator 82 in the right-left direction Y1. The axle 143 is adjacent to the intermediate shaft 141 and is disposed parallel to the intermediate shaft 141 and the motor shaft 85. A seventh bearing 107 is fitted onto a right end part of the axle 143. The seventh bearing 107 is held by a bearing holding part 133c formed in a rear part of the right side wall 133. Also, an eighth bearing 108 is fitted onto an intermediate part of the axle 143. The eighth bearing 108 is held by a bearing holding part 137a formed in an inner periphery of a left end part of the first extended part 137. The axle 143 is thereby rotatably supported by the gear case 132 via the seventh bearing 107 and the eighth bearing 108.

The output gear 144 is disposed near a right end part of the axle 143 and is meshed with the second intermediate gear 142b. The output gear 144 is formed to be larger in diameter than the second intermediate gear 142b.
A seal member 147 is fitted onto an intermediate part of the axle 143. The seal member 147 is disposed at the right of the eighth bearing 108 and seals an interval between an outer periphery of the axle 143 and an inner peripheral surface of the first extended part 137. The axle 143 projects out to the left of the gear case 132 from the first extended part 137 and is connected to the rear wheel 4.

FIG. 15 is a left side view of main parts of the electric vehicle 1 with illustration of a part of the swing unit 47 being omitted. An outer diameter R1 of the electric motor 5 is defined as twice a distance from a central axis 85a of the motor shaft 85 of the electric motor 5 to a part of the electric motor 5 furthest from the central axis 85a (outer peripheral part of the flange part 90b of the first synthetic resin member 90 of the first stator 86). The outer diameter R1 of the electric motor 5 is set to be larger than an outer diameter R2 of the input gear 140, larger than an outer diameter R3 of the intermediate gear 142 (outer diameter of the first intermediate gear 142a), and larger than an outer diameter R4 of the output gear 144. In the up-down direction Z1, the motor shaft 85 is disposed between the upper end part 78b and the lower end part 78c of the controller 78.

FIG. 16 is a partially sectional view of an arrangement of main parts of a periphery of the gear case 132 and shows a state in which the gear case 132 is viewed from the left. The intermediate shaft 141 is disposed at a position lower than the motor shaft 85 and is disposed at a position lower than the axle 143. More specifically, a central axis 141a of the intermediate shaft 141 is disposed at a position lower than the central axis 85a of the motor shaft 85 and is disposed at a position lower than a central axis 143a of the axle 143. Further, an upper end part 141b of the intermediate shaft 141 is disposed at a position lower than the upper end part 85b of the motor shaft 85 and is disposed at a position lower than an upper end part 143b of the axle 143.

The central axis 143a of the axle 143 is substantially matched in position in the up-down direction Z1 with the central axis 85a of the motor shaft 85. That is, the central axis 143a of the axle 143 and the central axis 85a of the motor shaft 85 are aligned substantially straightly in the front-rear direction X1.

As shown in FIG. 15, at least a part of the intermediate gear 142 is disposed at a position overlapping with the stator 82 (stator interior region F3) in a side view. In the present embodiment, an entirety of the intermediate gear 142 is disposed at a position overlapping with the stator 82 in a side view. In a side view, the intermediate gear 142 is disposed obliquely downward to the rear of the motor shaft 85 and is disposed at a position overlapping with the first tees 88 of the first stator 86.

At least a part of the axle 143 is disposed at a position overlapping with the stator 82 in a side view. In the present embodiment, substantially the entirety of the axle 143 is disposed at a position overlapping with the stator 82 in a side view.

In a side view, the axle 143 is disposed at a position overlapping with the first tees 88 of the first stator 86. A part of the output gear 144 that includes a front end part is disposed at a position overlapping with the stator 82 in a side view. Thus, in a side view, a part of the speed reduction mechanism 131 is disposed in the stator interior region F3 as a region surrounded by the outer peripheral surface of the first stator 88 of the stator 82 in a side view.

As shown in FIG. 9, a part of the axle 143 that projects outside the gear case 132 includes a male teeth part 143c and a male thread part 143d disposed at the left of the male teeth part 143c. In the present embodiment, the male teeth part 143c is a male spline. The male teeth part 143c is connected to the rear wheel 4. The rear wheel 4 is disposed at the left of the electric motor 5 and the motor case main body 71. The rear wheel 4 includes a wheel member 148 and a tire 149 mounted to the wheel member 148.

In the present embodiment, the wheel member 148 is a steel wheel. The wheel member 148 includes a hub 150, a disk 151, a tubular part 152 surrounding the hub 150, and a rim 153.
The hub 150 is fitted onto the male teeth part 143c of the axle 143. The wheel member 148 (rear wheel 4) is thereby connected to the axle 143 in an integrally rotatable manner. Also, a nut 154 is fixed to the male thread part 143d of the axle 143. The hub 150 is matched in position in the front-rear direction X1 with the rear end part 82a of the stator 82.

The disk 151 extends to radially outward sides of the wheel member 148 from a left end part of the hub 150. The disk 151 is formed to a shape that curves to the right in radially outward directions of the wheel member 148. A tip part of the tubular part 152 is inserted through an annular groove 138a formed in the second extended part 138 of the gear case 132.

As a whole, the rim 153 is formed to a cylindrical shape that surrounds the disk 151. The rim 153 includes a well part 153a connected to an outer peripheral part of the disk 151, bead seat parts 153b and 153c, and flange parts 153d and 153e. The well part 153a is formed to a groove-like shape when viewed along a circumferential direction of the wheel member 148.

The bead seat parts 153b and 153c are disposed to respectively connect with the inner peripheral surfaces of the bead parts 149a and 149b of the tire 149. The bead seat parts 153b and 153c extend in the right-left direction Y1 from an outer peripheral part of the well part 153a. The bead seat part 153b extends to the right from the well part 153a. The bead seat part 153c extends to the left from the well part 153a.

The flange parts 153d and 153e are disposed to respectively receive outer side surfaces of the bead parts 149a and 149b. The flange part 153d extends to radially outward sides of the wheel member 148 from a right end part of the bead seat part 153b. The flange part 153e extends to radially outward sides of the wheel member 148 from a left end part of the bead seat part 153c.

With the above arrangement, a wheel interior space S4 is formed by the disk 151 and the rim 153 of the wheel member 148. The wheel interior space S4 is formed to the right of the disk 151.

The wheel interior space S4 houses the left side wall 135 and a part of the second peripheral wall 136 of the gear case 132, a left end part of the motor shaft 85, a part of the input gear 140, a left end part of the intermediate shaft 141, a part of the first intermediate gear 142a, a part of the axle 143, the fourth, sixth, and eighth bearings 104, 106, and 108, and the seal member 147 of the speed reduction mechanism 131, and a brake device 155 to be described below.

The flange part 153d of the wheel member 148 is disposed so as to overlap in position in the right-left direction Y1 with a left end part of the motor shaft 85, a left end part of the input gear 140, and a left half part of the first intermediate gear 142a. The bead seat part 153b is disposed so as to overlap in position in the right-left direction Y1 with the fourth bearing 104, the left end part of the motor shaft 85, the sixth bearing 106, and a left half part of the intermediate shaft 141. Outer peripheral surfaces of the flange parts 153d and 153e are arranged as an outer peripheral surface 148a of the wheel member 148.

The tire 149 is formed using a synthetic rubber. The tire 149 includes a tread part 149e that surrounds the rim 153 and side walls 149d and 149c extending toward the rim 153 from respective right and left end parts of the tread part 149e. The bead parts 149a and 149b are formed in respective inner peripheral parts of the side walls 149c and 149d.

As shown in FIG. 15, in a side view, a region surrounded by the outer peripheral surface 148a of the wheel member 148 defines a wheel interior region F1. In a side view, the entirety of the speed reduction mechanism 131 is disposed in the wheel interior region F1. Also, a part of the electric motor 5 is disposed in the wheel interior region F1. A region of the stator 82 of the electric motor 5 excluding the front end part 82b is disposed in the wheel interior region F1.

That is, on basis of an intersection part of the first tees 88a, which, of the first stator 86 of the electric motor 5, is disposed most forwardly, and the outer peripheral surface 148a of the wheel member 148, the front end part 82b of the stator 82 that is positioned further forward than the intersection part is disposed outside the wheel interior region F1.

The drive motor 111 of the stator driving device 79 and a part of the second gear mechanism 113 is disposed further forward than the wheel interior region F1.
Also, the motor shaft 85 and the axle 143 are disposed so as to be aligned with the subframe 36 in the front-rear direction X1 and are matched in position in the up-down direction Z1 with a rear end part 36a of the subframe 36. By thus disposing the subframe 36 for supporting the battery 6 and a part of the speed reduction mechanism 131 so as to overlap in position in the up-down direction Z1, the battery 6 can be disposed at a lower position. A position of the seat 29 can thereby be made lower.

In a side view, a region surrounded by an outer peripheral surface of the tire 149 (outer peripheral edge part of the tread part 149e) and outside the wheel interior region F1 defines a tire interior region F2. The front end part 82b of the stator 82 of the electric motor 5 is disposed in the tire interior region F2. Also, a part of the drive motor 111 of the stator driving device 79 and a part of the second gear mechanism 113 are disposed in the tire interior region F2. Also, the bus bar 91U and a rear end part 78e of the controller 78 are disposed in the tire interior region F2.

As shown in FIG. 9, the brake device 155 is disposed in an interior of the wheel member 148. In the present embodiment, the brake device 155 is a drum brake device. Inside the wheel interior space S4, the brake device 155 is disposed between the hub 150 and the tubular part 152.

An operation shaft 156 extends to the right from the brake device 155. A right end part of the operation shaft 156 is fixed to an operation lever 157.
The operation lever 157 extends obliquely downward toward the rear from the operation shaft 156. As shown in FIG. 15, an operation cable 158 is connected to a lower end part of the operation lever 157. The operation cable 158 is arranged to be displaced in the front-rear direction X1 by operation of a brake lever (not shown) by the driver.

As shown in FIG. 16, a lubricating oil 159 for lubricating the speed reduction mechanism 131 is retained inside the gear case 132. A lubricating oil supply port 160 for supplying the lubricating oil 159 into the gear case 132 is formed at a rear end part of the first part 132a of the gear case 132. The lubricating oil supply port 160 is disposed at the rear of the electric motor 5 (further rearward than the rear end part 82a of the stator 82). The lubricating oil supply port 160 is formed to penetrate through the first part 132a of the gear case 132. A screw member 161 is detachably mounted to the lubricating oil supply port 160. By removing the screw member 161, the lubricating oil can be supplied to the lubricating oil supply port 160 from the right of the gear case 132.

The lubricating oil supply port 160 is disposed parallel to the right-left direction Y1 (in a horizontal direction). The lubricating oil 159 is thereby prevented from being retained above a lower end part of the lubricating oil supply port 160. Inside the gear case 132, the lubricating oil 159 is retained so as to immerse only a part of the gears 140, 142, and 144. The respective gears 140, 142, and 144 of the speed reduction mechanism 131 are thereby lubricated reliably while minimizing drive loss of the respective gears 140, 142, and 144 due to the lubricating oil 159.

More specifically, inside the gear case 132, an upper surface 159a of the lubricating oil 159 (lubricating oil supply port 160) is positioned above a lower end part 142c of the second intermediate gear 142b as a lower end of the speed reduction mechanism 131 and above a lower end part 144a of the output gear 144 and below a lower end part 140a of the input gear 140. Thus, when the input gear 140, the intermediate gear 142, and the output gear 144 are rotating, the lubricating oil 159 is scooped up by the intermediate gear 142 and the output gear 144 and lubricates the respective gears 140, 142, and 144.

Also, the gear case 132 has a lubricating oil discharging part 162 for discharging the lubricating oil 159 inside the gear housing space S3. The lubricating oil discharging part 162 is connected to a lower end of the gear housing space S3. Specifically, a peripheral wall of the gear case 132 is formed to a shape that is recessed downward in a side view.

FIG. 17 is a left side view of the swing unit 47 with a part near a rear end being broken away, and some of the members are indicated by alternate long and two short dashed lines. As shown in FIG. 16 and FIG. 17, the lubricating oil discharging part 162 is connected to the lower end of the gear housing space S3. The lubricating oil discharging part 162 is formed integral to the second peripheral wall 136 of the gear case 132 and extends downward from the second peripheral wall 136.

A lower end part of the lubricating oil discharging part 162 includes a lubricating oil discharge port 163. The lubricating oil discharge port 163 is disposed at an outer side of the electric motor 5 (first synthetic resin member 90) and the motor case 67 in a side view (see FIG. 15) and is positioned below the electric motor 5. The meaning of "at an outer side of the motor case 67" is, specifically, "out of the rotating shaft of the electric motor 5 (motor shaft 85) rather than the portion of the motor case 67 which covers the outer periphery of the electric motor 5 in a side view." A screw member 164 is detachably mounted as a drain bolt to the lubricating oil discharge port 163. By removing the screw member 164, the lubricating oil 159 retained in gear housing space S3 can be discharged to an exterior of the gear case 132.

As shown in FIG. 17, the swing unit 47 includes a first breather 165 and a second breather 166.
The first breather 165 is provided to open the space (motor housing space S2) inside the motor case 67 to a space exterior to the motor case 67 to prevent air pressure inside the motor case 67 from becoming excessively high. The first breather 165 includes a first boss 167 fixed to a connection part 75b of the side wall 75 of the motor case main body 71 and a first breather hose 168 connected to the first boss 167.

In a side view, the first boss 167 is disposed above the brake device 155 and is disposed further rearward than a front end part 132c of the gear case 132. The interior of the first boss 167 is formed to be hollow and continuous with the interior of the motor case 67. The first breather hose 168 is a rubber hose or other hose with flexibility. The first breather hose 168 extends rearward from the first boss 167, is curved downward at an on-the-way position, and is opened downward. The first breather hose 168 is thus connected via the first boss 167 to the motor case 67.

The second breather 166 is provided to open the space (gear housing space S3) inside the gear case 132 to a space exterior to the gear case 132 to prevent air pressure inside the gear case 132 from becoming excessively high. The second breather 166 includes a second boss 169 fixed to a connection part 135c of the left side wall 135 of the gear case 132 and a second breather hose 170 connected to the second boss 169.

In a side view, the second boss 169 is disposed above the brake device 155 and is disposed further rearward than the front end part 132c of the gear case 132. The second boss 169 is disposed further forward than the first boss 167. The interior of the second boss 169 is formed to be hollow and continuous with the interior of the gear case 132. The second breather hose 170 is a rubber hose or other hose with flexibility. The second breather hose 170 extends rearward from the second boss 169, is curved downward at an on-the-way position, and is opened downward. The second breather hose 170 is thus connected via the second boss 169 to the gear case 132.

As shown in FIG. 9, a rear end part 170a of the second breather hose 170 and a rear end part 168a of the first breather hose 168 are matched in position in the front-rear direction X1.
The rear end part 168a of the first breather hose 168 and the rear end part 170a of the second breather hose 170 are held at the same position where these rear end parts line from side to side (overlap with each other in a side view), by a holding member 171. Specifically, the holding member 171 may be a clamp member formed by bend-processing a metal rod, etc.

The holding member 171 is fixed using a screw member 139 to a rear part of the right side wall 133 of the gear case 132. The holding member 171 has a first holding part 173 and a second holding part 174 disposed at the rear of the right side wall 133. The first holding part 173 is formed to a cylindrical shape and holds a vicinity of a lower end of the rear end part 168a of the first breather hose 168. The second holding part 174 is formed to a cylindrical shape and holds a vicinity of a lower end of the rear end part 170a of the second breather hose 170. The first holding part 173 and the second holding part 174 are disposed adjacently and hold the respective breather hoses 168 and 170 at practically the same position.

As shown in FIG. 10A, the electric vehicle 1 includes a stand device 175 mounted to the swing unit 47. The stand device 175 is provided for supporting the electric vehicle 1 when the electric vehicle 1 is parked and is arranged to support the swing unit 47 in a state in which the rear wheel 4 is raised above the road surface A1.

The stand device 175 includes a spindle 176 connected to the swing unit 47 and a stand member 177 that is connected to the spindle 176 and is rotatable around the spindle 176.
The stand member 177 can be displaced to a separated position of being separated from the road surface A1 and to a grounded position of being grounded to the road surface A1. The stand device 175 at the separated position is indicated by solid lines. Also, the stand device 175 at the grounded position is indicated by alternate long and two short dashed lines. Unless noted in particular otherwise, the following description shall be based on a state in which the stand device 175 is set at the separated position.

The spindle 176 is inserted through a connection part 178 formed at a lower end of the front end part 67a of the motor case 67 and extends in the right-left direction Y1. The stand member 177 includes a U-shaped part 179 fixed to the spindle 176.

As shown in FIG. 9, in a plan view, the U-shaped part 179 is disposed so as to surround a front part of the rear wheel 4 from the front and from both the right and left sides. The U-shaped part 179 includes a first part 181 connected to the spindle 176 and a pair of second parts 182L and 182R that branch in the right-left direction Y1 from the first part 181.

The second part 182L extends to the rear left from the first part 181. A foothold part 183 is disposed at a tip part of the second part 182L. The foothold part 183 is a part on which the driver's foot is set when the driver operates the stand member 177 with his/her foot. The foothold part 183 is formed to a rod-like shape extending from the tip part of the second part 182L and is disposed at the left of the flange part 153e of the wheel member 148 of the rear wheel 4.

Also, a grounded member 184 is disposed at the tip part of the second part 182L. The grounded member 184 is formed by pressing a metal plate that is member separate from the second part 182L and is fixed to the second part 182L.
The second part 182R extends to the rear right from the first part 181. Besides not being provided with the foothold part 183, the second part 182R has a shape that is right-left symmetrical with respect to the second part 182L.

As shown in FIG. 15, in a side view, the foothold part 183 of the stand member 177 when positioned at the separated position is disposed to overlap with the front end part 82b of the stator 82 of the electric motor 5. Also, in a side view, tip parts of the respective second parts 182L and 182R of the stand member 177 and the foothold part 183 are disposed in the tire interior region F2.

When the driver is to displace the stand member 177 from the separated position to the grounded position, first, the driver steps down from the electric vehicle 1 and sets a tip of his/her foot on the foothold part 183. The driver then steps down on the foothold part 183 to rotate the stand member 177 around the spindle 176 and the stand member 177 is thereby displaced to the grounded position. The grounded member 184 of the stand member 177 that has been displaced to the grounded position is grounded on the road surface A1. In this state, the rear wheel 4 is in a state of being raised above the road surface A1.

FIG. 18A is a left side view of a periphery of the rear wheel 4. FIG. 18B is a right side view of a periphery of the rear wheel 4. As shown in FIG. 18A and FIG. 18B, the electric vehicle 1 includes a rear fender 185 disposed at an upper part of the rear wheel 4.
The rear fender 185 is provided for receiving rainwater, pebbles, etc., that are kicked up by the rear wheel 4 and is integrally swingable with the rear wheel 4 around the first pivot shaft 51. The rear fender 185 is disposed to cover an upper part of the tire 149 from above. The rear fender 185 includes an arcuate part 186 disposed above the tire 149, a pair of side plates 187L and 187R extending downward from the arcuate part 186, and a projecting part 188 extending to the front from the arcuate part 186.

A collar part 189 is disposed at a rear end part of the arcuate part 186. The collar part 189 extends obliquely downward to the rear and has a function of rectifying a flow of air that passes through the rear fender 185 during travelling of the electric vehicle 1.

The pair of side plates 187L and 187R are respectively disposed at the right and left of the rear wheel 4. The side plate 187R is disposed between the rear wheel 4 and the motor case 67. The side plate 187R has a recess 190 for avoiding contact with a shock absorber 69.

FIG. 19A is a left side view of the periphery of the rear wheel 4 and shows a state in which the rear fender 185 is removed. FIG. 19B is a right side view of the periphery of the rear wheel 4 and shows a state in which the rear fender 185 is removed. As shown in FIG. 19A and FIG. 19B, the electric vehicle 1 includes a fender support 191.

The fender support 191 includes a first part 192, a second part 193, and a third part 194. A front end part of the first part 192 is fixed using a screw member 74 to the connecting member 72 of the swing unit 47. The first part 192 is formed to a plate-like shape extending substantially rectilinearly to the rear from the connecting member 72. A rear end part 192a of the first part 192 is disposed further rearward than a rear end of the wheel member 148.

The second part 193 is formed to a U-like shape that is opened at a lower side and faces an upper part of the tire 149 from above and from both the right and left sides. A lower left end part 193a of the second part 193 contacts the first part 192. A lower right end part 193c of the second part 193 contacts the left side wall 135 of the gear case 132.

The third part 194 is a rod-like member extending obliquely upward toward the rear from the lower right end part 193c of the second part 193. A front end part of the third part 194 is fixed using a screw member 197 to the left side wall 135 of the gear case 132.

As shown in FIG. 18A and FIG. 18B, the first part 192 and the second part 193 are fixed using a screw member 195 to the side plate 187L of the rear fender 185. A right part of the second part 193 is fixed using a screw member 196 to the side plate 187R of the rear fender 185. A rear end part of the third part 194 is fixed using a screw member 198 to a rear end part of the side plate 187R.

As described above, with the present embodiment, an adequate torque can be applied to the rear wheel 4 without making the electric motor 5 large, the structure for cooling the electric motor 5 can be simplified, followability of the rear wheel 4 with respect to the road surface A1 can be improved, and yet a large maximum bank angle can be secured.

More specifically, the speed reduction mechanism 131 can perform speed reduction in the two stages of speed reduction between the input gear 140 and the intermediate gear 142 and speed reduction between the intermediate gear 142 and the output gear 144. A large speed reduction ratio (of no less than 10, for example,) can thereby be realized in the speed reduction mechanism 131 and thus an amount of amplification of the torque of the electric motor 5 can be increased. An adequate torque can thus be applied from the electric motor 5 to the rear wheel 4 without making the electric motor 5 large.

The electric motor 5 can thus be made compact because an adequate torque can be transmitted from the electric motor 5 to the rear wheel 4 without making the electric motor 5 large. The compact electric motor 5 is low in heat generation amount and in addition, the torque is greatly amplified by the speed reduction mechanism 131. That is, the present arrangement is not one in which the output of a large electric motor is used to apply a large torque to the rear wheel 4 and the output of the large electric motor is transmitted to the rear wheel without transmission through a speed reduction mechanism.

Thus, in comparison to a case of using a large electric motor without using the speed reduction mechanism 131, the output of the electric motor 5 required for the electric vehicle 1 to attain the same acceleration can be lessened in the case of using the speed reduction mechanism 131 and the compact electric motor 5. Heat generation by the electric motor 5 can thus also be suppressed. A cooling fan for forcibly cooling the electric motor 5 is thus unnecessary and the electric motor 5 can be cooled adequately by natural cooling of the electric motor 5 by a traveling wind of the electric vehicle 1. The arrangement for cooling the electric motor 5 can thereby be simplified.

Also, the stator 82 of the electric motor 5 is disposed at the position overlapping with at least a part of the intermediate gear 142 in a side view, the motor shaft 85 is disposed further forward than the intermediate shaft 141, and a part (front end part 82b) of the stator 82 is disposed further forward than the wheel member 148 in a side view. The electric motor 5, which is a heavy component, can thereby be disposed toward the front and near the first pivot shaft 51. Also, the electric motor 5 can be made small in moment of inertia about the first pivot shaft 51 during traveling of the electric vehicle 1 because the compact electric motor 5 that is lightweight can be used. Consequently, the rear wheel 4, which swings around the first pivot shaft 51 together with the electric motor 5 can be improved in followability with respect to the road surface A1.

Also, with the arrangement described in Japanese Published Unexamined Patent Application No. 2010-83366, indicated as Patent Document 1, only a single-stage speed reduction by the two gears of an input gear and an output gear is performed, and thus to obtain a large speed reduction ratio, an output gear of large diameter is necessary and thus an interval between the input gear and the output gear must be made wide.

In contrast, with the arrangement of the present embodiment, two-stage speed reduction by the three gears 140, 142, and 144 is performed and thus the interval between the input gear 140 and the output gear 144 does not have to be made wide to obtain a large speed reduction ratio. The three gears140, 142, and 144 can thus be disposed at narrow intervals. A distance between the central axes of the electric motor 5 and the rear wheel 4 can thus be shortened and the rear wheel 4 can be disposed further toward the front and nearer the first pivot shaft 51. The rear wheel 4 can thereby made small in moment of inertia about the first pivot shaft 51 during traveling of the electric vehicle 1. Consequently, the rear wheel 4 can be further improved in followability with respect to the road surface A1.

Further, the position in the right-left direction Y1 of a part of the intermediate gear 142 is overlapped with the position of the wheel member 148. A length (lateral width) in the right-left direction Y1 that the rear wheel 4 and the intermediate shaft 141 occupy as a whole can thereby be shortened. The rear wheel 4 and the intermediate shaft 141, which are disposed at positions of comparatively low height from the road surface A1, can thus be configured to be short in lateral width as a whole, and thus a maximum value of an angle (maximum bank angle) by which the electric vehicle 1 can be tilted in the right-left direction Y1 to make a turn can be made large.

Also, in a side view, the speed reduction mechanism 131 is positioned inside the wheel interior region F1 and in a side view, a part of the speed reduction mechanism 131 is disposed inside the stator interior region F3. It thereby becomes possible to dispose more parts of the speed reduction mechanism 131 inside the wheel interior space S4 and a length that the wheel member 148, the speed reduction mechanism 131, and the electric motor 5 occupy as a whole in the right-left direction Y1 can be shortened. The swing unit 47 is thereby made less likely to contact the road surface A1 when the electric vehicle 1 is tilted to make a turn and the maximum bank angle can thus be increased.

Also, in a side view with the speed reduction mechanism 131, the outer diameters R2, R3, and R4 of the input gear 140, intermediate gear 142, and output gear 144 are all smaller than the outer diameter R1 of the electric motor 5. It thereby becomes possible to dispose the speed reduction mechanism 131 inside the wheel member 148 (wheel interior space S4) more reliably and the length that the wheel member 148, the speed reduction mechanism 131, and the electric motor 5 occupy as a whole in the right-left direction Y1 can be shortened. The swing unit 47 is thereby made less likely to contact the road surface A1 when the electric vehicle 1 is tilted to make a turn and the maximum bank angle can thus be increased.

Further, the intermediate shaft 141 is disposed below the motor shaft 85 and the axle 143. The respective gears 140, 142, and 144 can thereby be disposed across a wider range inside the wheel interior space S4 while keeping the speed reduction mechanism 131 within the wheel interior space S4 in a side view. The outer diameters of the respective gears 140, 142, and 144 can thereby be increased. Consequently, the speed reduction ratio of the speed reduction mechanism 131 can be increased.

The lubricating oil supply port 160 is disposed at a position to the rear of the electric motor 5. By enabling the electric motor 5 to be disposed toward the front as described above, the lubricating oil supply port 160 can be disposed at the rear end part of the gear case 132. At the rear end part of the gear case 132, obstructing parts are few and the lubricating oil supply port 160 can thus be operated to open and close easily by a hand. Also, a height position of the lubricating oil supply port 160 can be set freely and thus the amount of lubricating oil in the gear case 132 can be predefined readily by the positioning of the lubricating oil supply port 160. Also, a lubricating oil pouring work can be performed without removing the second part 132b of the motor case 67.

Further, the lubricating oil supply port 160 is disposed above the lower end of the speed reduction mechanism 131 (the lower end part 142c of the intermediate gear 142). The lubricating oil 159 can be scooped up inside the gear case 132 by at least the intermediate gear 142 and the lubricating oil 159 can thus be supplied reliably to the respective gears 140, 142, and 144 of the speed reduction mechanism 131. Also, the optimum height (oil level) of the lubricating oil 159 can be realized. The oil level can thereby be set to maximize the lubrication effect of the lubricating oil 159 and minimize drive loss of the speed reduction mechanism 131 due to viscous drag of the lubricating oil 159.

Also, the lubricating oil discharge port 163 is disposed outside the motor case 67 in a side view and thus the lubricating oil discharge port 163 can be operated readily by a hand and a work of discharging the lubricating oil 159 can be performed readily.

Further, the pressure inside the gear case 132 and the pressure inside the motor case 67 can be maintained at atmospheric pressure by the first and second breather hoses 168 and 170. Also, the respective breather hoses 168 and 170 are held at the same position by the holding member 171 and thus the respective breather hoses 168 and 170 can be mounted readily at the same time and a work of mounting the respective breather hoses 168 and 170 is easy.

Also, when the stand member 177 is at the separated position, the foothold part 183 is disposed to overlap in a side view with the electric motor 5 that is disposed toward the front and near the first pivot shaft 51. The foothold part 183 is thus also positioned toward the front and the driver in the state of standing on the road surface A1 while holding the handle 11 can set his/her foot readily on the foothold part 183. The stand member 177 can thus be improved in operability.

Moreover, the electric motor 5 and the foothold part 183 are disposed at the right and left so as to sandwich the rear wheel 4, and thus amounts of protrusion of parts of the electric vehicle 1 in the right-left direction Y1 from the rear wheel 4 can be reduced. Consequently, the maximum bank angle can be increased.
<Second Embodiment>

FIG. 20 is a left side view of main parts of an electric vehicle 1A according to a second embodiment of the present invention. In the following, points of difference with respect to the first embodiment shall mainly be described. Arrangements that are the same as those of the first embodiment are provided with the same signs and description thereof shall be omitted.

The electric vehicle 1A differs from the electric vehicle 1 in an arrangement of a swing unit 47A and an arrangement of a stand device 175A.
The swing unit 47A has an arrangement where the swing unit 47 of the first embodiment is inverted in the right-left direction Y1. Thus, a motor case main body 71A, an electric motor 5A, a gear case 132A, etc., of the swing unit 47A are disposed at the left of the rear wheel 4.

The stand device 175A includes a spindle 176A connected to the second frame part 22 of the vehicle body frame 2 and the stand member 177 that is connected to the spindle 176A and is rotatable around the spindle 176A.
The spindle 176A is connected to the lower end part 22a of the second frame part 22 and extends in the right-left direction Y1. The foothold part 183 of the stand member 177 is disposed further forward than the swing unit 47A. The stand member 177 is thus disposed further forward than the electric motor 5A in a side view. The foothold part 183 of the stand member 177 is disposed at the left of the rear wheel 4 in the right-left direction Y1.

When the driver is to displace the stand member 177 from the separated position to the grounded position, first, the driver steps down from the electric vehicle 1A and sets a tip of his/her foot on the foothold part 183. The driver then steps down on the foothold part 183 to rotate the stand member 177 around the spindle 176A. The stand member 177 is thereby displaced to the grounded position. The respective grounded members 184 of the stand member 177 that has been displaced to the grounded position are grounded on the road surface A1.

With the present embodiment, the foothold part 183 in the state in which the stand member 177 is at the separated position can be disposed toward the front. The driver in the state of standing on the road surface A1 while holding the handle 11 can thus set his/her foot readily on the foothold part 183. The stand member 177 can thus be improved in operability.

Although with the respective embodiments described above, an arrangement in which the intermediate shaft 141 is disposed below the motor shaft 85 and the axle 143 was described, the present invention is not restricted thereto. The intermediate shaft 141 may be matched in position in the up-down direction Z1 with respect to at least one of either of the motor shaft 85 and the axle 143 or may be disposed above the motor shaft 85 and the axle 143.

Also, a plurality of holes may be provided in the disk 151 along the circumferential direction of the disk 151 of the wheel member 148.
Further, the pivot shafts 52L and 52R may be eliminated and the swing unit 47 may be made swingable only around the first pivot shaft 51.

Also, the present invention may be applied to an electric vehicle other than a scooter.
Besides the above, various design changes may be applied within the scope of the matters described in the claims.

1, 1A ... Electric vehicle
2 ... Vehicle body frame
4... Rear wheel
5, 5A ... Electric motor
51 ... First pivot shaft (pivot shaft)
52L, 52R ... Second pivot shaft (pivot shaft)
67 ... Motor case
75b ... Connection part (for connection to a first breather hose)
81 ... Rotor
82 ... Stator
85 ... Motor shaft
131 ... Speed reduction mechanism
132, 132A ... Gear case
135c ... Connection part (for connection to a second breather hose)
140 ... Input gear
141 ... Intermediate shaft
142 ... Intermediate gear
143 ... Axle
144 ... Output gear
148 ... Wheel member
148a ... Outer peripheral surface
149 ... Tire
160 ... Lubricating oil supply port
163 ... Lubricating oil discharge port
168 ... First breather hose
170 ... Second breather hose
171 ... Holding member
177 ... Stand member
183 ... Foothold part
A1 ... Road surface
F1 ... Wheel interior region (region surrounded by the outer peripheral surface of the wheel member in a side view)
F3 ... Stator interior region (region surrounded by the stator in a side view)
R1 ... Outer diameter of the electric motor
R2 ... Outer diameter of the input gear
R3 ... Outer diameter of the intermediate gear
R4 ... Outer diameter of the output gear
Y1 ... Right-left direction (vehicle right-left direction)

Claims

An electric vehicle comprising:
an electric motor including a stator, a rotor facing the stator, and a motor shaft fixed to the rotor;
an intermediate shaft disposed adjacent to the motor shaft;
an axle disposed adjacent to the intermediate shaft;
a speed reduction mechanism including an input gear disposed on the motor shaft, an intermediate gear disposed on the intermediate shaft and meshed with the input gear, and an output gear disposed on the axle and meshed with the intermediate gear;
a motor case housing the electric motor and connected to a vehicle body frame in a manner enabling swinging about a pivot shaft;
a gear case fixed to the motor case, housing the speed reduction mechanism, and from which the axle projects outward; and
a rear wheel including a wheel member connected to the axle and a tire mounted to the wheel member; and
wherein at least a part of the intermediate gear is disposed at a position overlapping with the stator in a side view,
a part of the intermediate gear is disposed to overlap in position in a vehicle right-left direction with the wheel member,
the intermediate shaft is disposed further forward than the axle,
the motor shaft is disposed further forward than the intermediate shaft, and
in a side view, a part of the stator is disposed further forward than the wheel member.
The electric vehicle according to Claim 1, wherein, in a side view, the speed reduction mechanism is positioned inside a region surrounded by an outer peripheral surface of the wheel member and a part of the speed reduction mechanism is disposed inside a region surrounded by the stator.
The electric vehicle according to Claim 1 or 2, wherein, in a side view, outer diameters of the input gear, intermediate gear, and output gear of the speed reduction mechanism are all made smaller than an outer diameter of the electric motor.
The electric vehicle according to any one of Claims 1 to 3, wherein the intermediate shaft is disposed below the motor shaft and the axle.
The electric vehicle according to any one of Claims 1 to 4, wherein, in the gear case, a lubricating oil supply port is disposed at a position to the rear of the electric motor.
The electric vehicle according to Claim 5, wherein the lubricating oil supply port is disposed above a lower end of the speed reduction mechanism.
The electric vehicle according to any one of Claims 1 to 6, wherein the gear case is provided with a lubricating oil discharge port disposed outside the motor case in a side view.
The electric vehicle according to any one of Claims 1 to 7, further comprising: a first breather hose connected to the motor case; and a second breather hose connected to the gear case; and
wherein the first breather hose and the second breather hose extend rearward from connection parts with respect to the corresponding cases and are held at the same position where these breather hoses line from side to side, by a holding member.
The electric vehicle according to any one of Claims 1 to 8, further comprising: a stand member that has a foothold part for setting a foot, is mounted to the motor case, and can be displaced to a grounded position of being grounded to a road surface and to a separated position separated from the road surface, and
wherein when the stand member is at the separated position, the foothold part is disposed to overlap with the electric motor in a side view,
the electric motor is disposed at the right of the rear wheel, and the foothold part is disposed at the left of the rear wheel.
The electric vehicle according to any one of Claims 1 to 8, further comprising: a stand member that has a foothold part for setting a foot, is mounted to the vehicle body frame, and can be displaced to a grounded position of being grounded to a road surface and to a separated position separated from the road surface; and
wherein the electric motor and the foothold part are disposed at the left of the rear wheel, and
when the stand member is at the separated position, the foothold part is disposed further forward than the electric motor in a side view.