JP2021030853A - Wheel drive mechanism for electric two-wheel vehicle - Google Patents

Abstract

To improve cooling efficiency of an electric motor in an electric two-wheel vehicle compared to the prior art.SOLUTION: A wheel drive mechanism is configured to drive wheels with an electric motor such that the wheels rotate. An output shaft of the electric motor and an axle of the wheels are in an orthogonal relation. The output shaft and the axle are connected by using a predetermined power transmission mechanism. A drive circuit that electrically drives the electric motor is disposed at an upstream side of the electric motor in the flow direction of travel wind.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wheel drive mechanism for electric motorcycles.

Patent Document 1 below discloses a saddle-mounted electric vehicle. This saddle-mounted electric vehicle is provided with a drive wheel, an electric motor for driving the drive wheel, a battery for storing electric power to be supplied to the electric motor, a light unit, and the light unit, and is electrically connected to the battery. It is a motor-driven motorcycle equipped with a charging inlet. That is, this saddle-mounted electric vehicle is an electric two-wheeled vehicle that travels by transmitting the driving force of the electric motor to the rear wheels (driving wheels) via a transmission member such as a chain.

Japanese Unexamined Patent Publication No. 2019-043286

By the way, in a saddle-mounted electric vehicle, the output shaft (rotating shaft) of the electric motor and the axle (rotating shaft) of the rear wheels (driving wheels) are arranged in parallel, and the two are connected by a transmission member consisting of a sprocket and a chain. By doing so, the rotational power of the electric motor is transmitted to the rear wheels.

However, in such a saddle-mounted electric vehicle, the occupant, the vehicle frame, and / or the body cover become obstacles, and the running wind effectively acts on the electric motor and the drive circuit that electrically drives the electric motor. It is difficult to cool (air-cool). In electric motorcycles, improving the cooling efficiency of electric motors and / and drive circuits is an extremely important technical issue.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the cooling efficiency of an electric motor in an electric motorcycle as compared with the conventional case.

In order to achieve the above object, in the present invention, as a first solution relating to a wheel drive mechanism, a wheel drive mechanism for rotationally driving a wheel using an electric motor, the output shaft of the electric motor and the wheel. The output shaft and the axle are connected by using a predetermined force transmission mechanism, and the electric motor is electrically driven upstream of the electric motor in the flow direction of the traveling wind. The means that a circuit is provided is adopted.

In the present invention, as a second solution relating to the wheel drive mechanism, in the first solution, the force transmission mechanism is a worm gear, and the electric motor is a switched reluctance motor or an induction motor. Is adopted.

In the present invention, as a third solution relating to the wheel drive mechanism, in the first or second solution, the drive circuit is formed to be smaller than the electric motor.

In the present invention, as a fourth solution for the wheel drive mechanism, in any of the first to third solutions, a heat radiation fin is provided on the tip surface of the drive circuit where the traveling wind collides. Adopt the means of being.

In the present invention, as a fifth solution relating to the wheel drive mechanism, in any one of the first to fourth solutions, the heat radiating fin has a direction in which the traveling wind colliding with the tip surface is guided to the outer circumference. Adopt the means that it is formed in.

In the present invention, as a sixth solution relating to the wheel drive mechanism, in any of the first to fifth solutions, heat radiation fins are provided on the outer peripheral surface of the drive circuit and the outer peripheral surface of the electric motor, respectively. Is provided.

According to the present invention, it is possible to improve the cooling efficiency of an electric motor in an electric motorcycle as compared with the conventional case.

It is a schematic diagram which shows the overall structure of the electric motorcycle which concerns on one Embodiment of this invention. It is a schematic diagram which shows the detailed structure of the wheel drive mechanism which concerns on one Embodiment of this invention. It is a schematic diagram which shows the end heat dissipation structure of the motor unit in one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The electric two-wheeled vehicle A according to the present embodiment is a relatively small motorcycle, and as shown in FIG. 1, the body frame 1, the front fork 2, the front wheel 3, the steering handle 4, the rear suspension 5, the rear wheel 6, and the body cover. 7. The seat 8, the motor unit 9, the force transmission mechanism 10, the battery 11, and the like are provided. In addition, in FIG. 1, arrows indicating front / rear, left / right, and up / down of the electric motorcycle A are added.

The body frame 1 is a strength component having a predetermined shape that bears the mechanical strength of the electric motorcycle A. The front fork 2 is rotatably provided at the tip of the vehicle body frame 1 and supports the front wheel 3 in a stretchable manner. That is, the front fork 2 is a component responsible for cushioning performance in traveling of the electric motorcycle A, and the front wheel 3 is rotatably mounted on the lower end portion.

The front wheel 3 is provided at the lower end of the front fork 2 with the left-right direction as an axle (front wheel axle), and is rotatable around the front wheel axle. The steering handle 4 is provided so as to project in the left-right direction at the upper end of the front fork 2. The left and right ends (both ends) of the steering handle 4 are portions that the passenger grips to set the traveling direction of the electric motorcycle A.

The rear suspension 5 is provided at the rear end of the vehicle body frame 1 and supports the rear wheels 6 in a stretchable manner. The rear suspension 5, together with the front fork 2, is a component that bears cushioning performance in the running of the electric motorcycle A, and the rear wheel 6 is rotatably mounted on the lower end portion. Similar to the front wheel 3 described above, the rear wheel 6 is provided at the lower end portion of the rear suspension 5 with the left-right direction as the axle (rear wheel axle 6a), and is rotatable around the rear wheel axle 6a. The rear wheel 6 is a drive wheel of the electric motorcycle A.

The body cover 7 is a resin member that covers the body frame 1 and some parts, and is responsible for protecting various parts and ensuring aerodynamic characteristics. In the body cover 7, a footboard 7a on which the passenger puts his / her foot is formed at a substantially central portion in the front-rear direction. Further, in the body cover 7, the rear portion of the front wheel 3 is provided with an opening (running wind intake port 7b) for taking in the running wind. The seat 8 is provided on the vehicle body frame 1 and is a seat on which a passenger sits.

The motor unit 9 is a power source for traveling the electric motorcycle A, and is provided under the seat 8 and behind the footboard 7a as shown in the figure. As shown in FIG. 2, the motor unit 9 is fixed to the vehicle body frame 1 in a posture in which the output shaft 9a (rotational shaft) is in the front-rear direction. Such a motor unit 9 generates rotational power around the output shaft 9a based on the DC power supplied from the battery 11.

The motor unit 9 will be described in more detail with reference to FIG. 2. The motor unit 9 includes a motor main body portion 9b and a PCU portion 9c. The motor main body 9b includes a columnar motor housing 9d having a predetermined diameter and a predetermined length. Further, the motor housing 9d includes a pair of end faces parallel to each other in the front-rear direction and an annular peripheral surface in which heat radiation fins 9e are formed at predetermined intervals.

The heat radiating fins 9e are strip-shaped portions extending in the front-rear direction and having a predetermined thickness on the peripheral surface of the motor housing 9d. Inside the motor housing 9d, the electric motor is housed in a posture in which the output shaft 9a (rotating shaft) is in the front-rear direction. This electric motor is a heat generating component. The heat radiation fins 9e of the motor housing 9d are provided to effectively release the heat generated by the electric motor into the air. The electric motor in the present embodiment is, for example, a switched reluctance motor or an induction motor.

The PCU portion 9c is provided on the end face located on the front side of the pair of end faces of the motor main body portion 9b (motor housing 9d), and is a columnar PCU housing 9f having a predetermined diameter and a predetermined length. It has. Further, in the PCU housing 9f, of the pair of end faces parallel to each other in the front-rear direction, the rear end face is flush with the front end face of the motor housing 9d. That is, the PCU housing 9f is a metal housing integrally formed with the motor housing 9d.

In such a PCU housing 9f, a plurality of heat radiating fins 9g are formed at predetermined intervals on the circumferential surface of the ring, and a plurality of heat radiating fins 9h are formed on the front end surface (tip surface). Focusing on the heat radiating fins 9h on the tip surface, the heat radiating fins 9h are provided so as to extend from the center of the circular tip surface toward the outer circumference as shown in FIG. That is, the heat radiating fins 9h are formed in a direction that guides the traveling wind that collides with the tip surface to the outer periphery.

Further, the PCU housing 9f houses a drive circuit (power conversion circuit) that converts the DC power supplied from the battery 11 into AC power and supplies it to the electric motor in the motor housing 9d. This drive circuit is a heat generating component like the electric motor described above. The heat radiation fins 9g and 9h provided on the PCU housing 9f are provided to effectively release the heat generated by the electric motor into the air.

Here, when the electric motorcycle A is in the traveling state, the electric motorcycle A is exposed to the traveling wind flowing from the front to the rear as shown by the arrows in FIGS. 1 to 3. Focusing on the electric motor housed in the motor housing 9d and the drive circuit housed in the PCU housing 9f, the drive that electrically drives the electric motor upstream of the electric motor in the flow direction of the traveling wind. A circuit is provided. Further, the drive circuit, that is, the PCU housing 9f accommodating the drive circuit is formed to be smaller than the electric motor, that is, the motor housing 9d accommodating the electric motor.

The force transmission mechanism 10 is a mechanism for transmitting the rotational power generated by the motor unit 9 to the rear wheels 6, and includes a worm gear 10a and a transmitter 10b. The worm gear 10a is a first transmission mechanism that converts the direction of the rotation center of the rotational power generated by the motor unit 9 into a direction orthogonal to the direction, and is a screw gear 10c (worm), a helical gear 10d (worm wheel), and a rotation shaft. It includes 10e and a first bearing 10f.

The screw gear 10c is a cylindrical member, spiral screw teeth are formed on the outer peripheral surface, and the output shaft 9a of the motor unit 9 is press-fitted onto the inner peripheral surface. The screw tooth gear 10d is a hollow disk-shaped member, and a tooth tooth is formed on the outer peripheral surface and a rotating shaft 10e is press-fitted on the inner peripheral surface.

The rotating shaft 10e is provided in a posture perpendicular to the output shaft 9a, and is rotatably supported by the first bearing 10f. The first bearing 10f is provided on both sides of the tooth gear 10d on the rotating shaft 10e, and rotatably supports the rotating shaft 10e, that is, the tooth gear 10d. The force transmission mechanism 10 is provided with a second bearing 10g that rotatably supports the tip of the output shaft 9a.

Such a worm gear 10a orthogonally converts the rotational power of the output shaft 9a and transmits it to the rotary shaft 10e. That is, the worm gear 10a is a gear mechanism that converts the rotation center direction (output center direction) of the output shaft 9a into a rotation shaft 10e having a rotation center direction orthogonal to the output center direction.

The transmitter 10b includes a first sprocket 10h, a second sprocket 10i, and a belt 10j, and is a second transmission mechanism that transmits the rotational power of the rotating shaft 10e to the rear wheel axle 6a at a predetermined rotation ratio. The rotating shaft 10e of the first sprocket 10h is press-fitted and fixed to the central opening, and rotates integrally with the rotating shaft 10e.

In the second sprocket 10i, the rear wheel axle 6a is press-fitted and fixed to the central opening, and the second sprocket 10i rotates integrally with the rear wheel axle 6a. The belt 10j is an endless belt that is hung around the first sprocket 10h and the second sprocket 10i, and transmits the rotational force of the first sprocket 10h to the second sprocket 10i. The rotation ratio of the transmitter 10b is determined by the gear ratio of the first sprocket 10h and the second sprocket 10i.

Here, the motor unit 9 and the force transmission mechanism 10 described above constitute the wheel drive mechanism in the present embodiment. That is, the motor unit 9 and the force transmission mechanism 10 rotate and drive the rear wheels 6 (wheels) using the motor unit 9 (electric motor), and the output shaft 9a and the rear wheels of the motor unit 9 (electric motor). The axle 6a of the 6 (wheel) is in an orthogonal relationship, and the output shaft 9a and the axle 6a are connected by using a predetermined force transmission mechanism 10.

The battery 11 is a rechargeable secondary battery, and is provided in the vicinity of the motor unit 9 as shown in the figure. The battery 11 is a power source for operating the motor unit 9, and supplies DC power of a predetermined voltage to the motor unit 9. Such a battery 11 is, for example, a lithium ion battery or an all-solid-state battery.

Next, the actions and effects of the electric motorcycle A according to the present embodiment will be described in detail.
The electric two-wheeled vehicle A converts the DC power of the battery 11 into AC power by the drive circuit of the motor unit 9, and supplies the AC power to the electric motor to generate running power (rotational power). That is, in this electric motorcycle A, the rotational power output by the wheel drive mechanism is transmitted to the axle 6a, so that the rear wheels 6 (driving wheels) are rotationally driven to obtain running power.

Here, when the electric motorcycle A travels at a predetermined speed, the traveling wind flows into the electric motorcycle A from the front. This traveling wind is taken in from the traveling wind intake 7b of the body cover 7 and guided to the front side of the motor unit 9. That is, as shown by the arrows in FIGS. 1 to 3, the motor unit 9 is exposed to the traveling wind flowing from the front to the rear.

Explaining the traveling wind flowing into the motor unit 9 in more detail, the traveling wind flows so as to collide with the front end surface of the PCU housing 9f, and is guided by the heat radiation fins 9h provided on the front end surface to the front side. It flows toward the outer periphery of the end surface, and further flows backward from the outer periphery via the peripheral surface of the PCU housing 9f.

When the traveling wind flows in the vicinity of the motor unit 9, the drive circuit in the PCU housing 9f is formed by the traveling wind colliding with the front end surface of the PCU housing 9f and the heat radiation fins 9h provided on the front end surface. Effectively cooled by action. Further, this drive circuit is also effectively cooled by the action of the heat radiation fins 9g provided on the peripheral surface of the PCU housing 9f.

Further, the traveling wind that has passed through the peripheral surface of the PCU housing 9f flows from the peripheral surface of the PCU housing 9f to the vicinity of the outer periphery of the front end surface of the motor housing 9d. Then, the traveling wind flows backward from the vicinity of the outer periphery via the peripheral surface of the motor housing 9d. That is, the traveling wind that has passed around the PCU portion 9c subsequently flows around the motor main body portion 9b and flows away to the rear.

When flowing from the peripheral surface of the PCU housing 9f to the vicinity of the outer periphery of the front end surface of the motor housing 9d, the PCU housing 9f is formed to be smaller (smaller diameter) than the motor housing 9d, in other words, the motor housing. Since the body 9d is formed to be larger (larger diameter) than the PCU housing 9f, the running wind is gathered in a region closer to the peripheral surface, that is, the peripheral surface of the motor housing 9d in the vicinity of the peripheral surface of the motor housing 9d. It flows like it sticks. Therefore, the heat dissipation effect of the heat radiation fins 9e provided on the peripheral surface of the motor housing 9d can be further improved.

If the PCU housing 9f and the motor housing 9d are formed to have the same shape (same diameter), the traveling wind flowing from the region near the peripheral surface of the CU housing 9f to the region near the peripheral surface of the motor housing 9d is on the downstream side. The more you go, the more it flows in the area away from the peripheral surface. That is, the traveling wind flowing in the region near the peripheral surface of the PCU housing 9f and the motor housing 9d flows in the radial direction of the PCU housing 9f and the motor housing 9d, that is, the PCU housing 9f and the motor housing 9d as it goes downstream. It spreads and flows in the radial direction orthogonal to the central axis.

Therefore, when the PCU housing 9f and the motor housing 9d are formed to have the same shape (same diameter), the traveling wind flows on the peripheral surface of the motor housing 9d so as to be relatively far from the peripheral surface. , The heat dissipation effect of the heat dissipation fins 9e is reduced.

According to the present embodiment, since the electric motorcycle A includes a wheel drive mechanism including a motor unit 9 and a force transmission mechanism 10, it is possible to improve the cooling efficiency of the electric motor in the electric motorcycle A as compared with the conventional case.

Further, according to the present embodiment, since the worm gear 10a is adopted as a component of the force transmission mechanism 10, even when a switched reluctance motor or an induction motor is adopted as the electric motor, the engine (internal combustion engine) It is possible to obtain a running effect similar to that of the engine brake in.

That is, in the switched reluctance motor or the induction motor, a regenerative load is not generated when the supply of the drive current from the drive circuit is stopped, but the worm gear 10a has different transmission efficiencies between forward rotation and reverse rotation, so that the engine (internal combustion engine) It is possible to obtain a running effect similar to that of the engine brake in.

The present invention is not limited to the above embodiment, and for example, the following modifications can be considered.
(1) In the above embodiment, the case where the present invention is applied to a relatively small motorcycle has been described, but the present invention is not limited thereto. The present invention is also applicable to a saddle-type electric vehicle as shown in Patent Document 1, that is, a relatively large motorcycle.

(2) In the above embodiment, a running effect similar to that of an engine brake is obtained by adopting the worm gear 10a, but the present invention is not limited to this. A running effect similar to that of an engine brake may be obtained by adopting an electric motor that generates an induced electromotive force to generate a regenerative load when the supply of the drive current from the drive circuit is stopped. The electric motor in this case is a motor having a permanent magnet as a magnetic pole, and is, for example, a synchronous motor.

(2) In the above embodiment, the motor unit 9 is cooled by using the traveling wind, but the present invention is not limited to this. A fan that forcibly blows cooling air onto the motor unit 9 may be provided in front of the motor unit 9.

A Electric motorcycle 1 Body frame 2 Front fork 3 Steering handle 4 Front wheel 5 Rear wheel 6 Rear suspension 7 Body cover 7a Footboard 7b Travel wind intake 8 Seat 9 Motor unit 9a Output shaft 9b Motor body 9c PCU part 9d Motor housing ( Electric motor)
9e Heat dissipation fin 9f PCU housing (drive circuit)
9g radiating fin 9h radiating fin 10 force transmission mechanism 10a worm gear 10b transmitter 10c screw gear 10d screw tooth gear 10e rotating shaft 10f first bearing 10g second bearing 10h first sprocket 10i 2 sprocket 10j belt 11 battery

Claims (6)

A wheel drive mechanism that rotates and drives wheels using an electric motor.
The output shaft of the electric motor and the axle of the wheel are in an orthogonal relationship, and the output shaft and the axle are connected by using a predetermined force transmission mechanism.
A wheel drive mechanism for electric motorcycles, characterized in that a drive circuit for electrically driving the electric motor is provided on the upstream side of the electric motor in the flow direction of the running wind. The wheel drive mechanism for an electric motorcycle according to claim 1, wherein the force transmission mechanism is a worm gear, and the electric motor is a switched reluctance motor or an induction motor. The wheel drive mechanism for an electric motorcycle according to claim 1 or 2, wherein the drive circuit is formed to be smaller than the electric motor. The wheel drive mechanism for an electric motorcycle according to any one of claims 1 to 3, wherein a heat radiating fin is provided on a front end surface of the drive circuit where the traveling wind collides. The wheel drive mechanism for an electric motorcycle according to any one of claims 1 to 4, wherein the heat radiating fin is formed in a direction of guiding the traveling wind colliding with the tip surface to the outer periphery. .. The wheel drive mechanism for an electric motorcycle according to any one of claims 1 to 5, wherein heat radiation fins are provided on the outer peripheral surface of the drive circuit and the outer peripheral surface of the electric motor. ..

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