JP7675425B2 - electric motorcycle - Google Patents

Description

The present invention relates to an electric motorcycle that uses an electric motor as a drive source to apply driving force to the rear wheel, and in particular to an electric motorcycle equipped with a rear swing arm having a new specific structure.

In recent years, electric motorcycles have been proposed that use an electric motor instead of an internal combustion engine as the drive source that applies driving force to the rear wheel of straddle-type motorcycles (including motorized bicycles).

However, most electric motorcycles proposed to date have adopted an in-wheel type electric motor that directly drives the rear wheel axle, as described in Patent Document 1 (JP Patent Publication 2011-152901).

However, electric motorcycles that use in-wheel type electric motors have the problem that it is difficult to achieve left-right weight balance because the electric motor is placed on only one side of the rear wheel. As is well known, left-right balance is important for motorcycles that have one front wheel and one rear wheel to ensure steering stability and course keeping, and particularly lightweight motorcycles and motorcycles for sports or leisure use require even stricter weight balance.

As described in Patent Document 1, it is possible to set the total left-right weight balance by shifting the center of gravity of equipment other than the electric motor to the opposite side to the electric motor. However, it is not easy to correct the weight balance caused by placing the electric motor only on one side of the rear wheels by setting the center of gravity of other equipment, and even if the total left-right weight balance could be achieved, the left-right weight balance is disturbed by the electric motor and other equipment alone, so it is not possible to completely eliminate the adverse effects on maneuverability, course keeping, turning performance, etc. caused by the bias of the electric motor.

In addition, because the electric motor, which is a heavy object, is located near the rear end of the vehicle in the fore-and-aft direction, it is easy for the load distribution in the fore-and-aft direction to deviate significantly from the ideal in motorcycles, where weight balance is important. This can lead to problems such as poor straight-line stability and poor handling when cornering.

In addition, in conventional electric motorcycles that use an in-wheel type electric motor, the electric motor is mounted near the rear end of the rear swing arm, which is capable of swinging around a pivot shaft relative to the body frame. This inevitably increases the distance from the pivot shaft to the electric motor, resulting in a large moment of inertia around the pivot shaft. This can lead to problems such as poor ability of the rear tire to follow uneven road surfaces, which can have a negative impact on ride comfort and handling stability.

A first aspect of the present invention is an electric motorcycle having a front wheel and a rear wheel mounted on the front and rear of a body frame, and an electric motor as a drive source that applies a driving force to the rear wheel, wherein a rear swing arm extending rearward from the body frame is attached so as to be swingable about a pivot shaft, and the rear wheel is rotatably supported by a rear axle shaft attached to a rear end portion of the rear swing arm, while the electric motor is positioned forward of the pivot shaft of the rear swing arm with a rotation output shaft facing in the vehicle width direction, and is fixedly disposed and supported relative to the rear swing arm, and the rotation output shaft of the electric motor is connected to This electric motorcycle is characterized in that a drive side sprocket is attached to the rear wheel and a driven side sprocket is attached to the rear wheel, and driving force is transmitted from the drive side to the driven side via a chain, while the drive side sprocket and the driven side sprocket are arranged opposite each other across the pivot shaft, the chain stretched between the sprockets is located above and below the pivot shaft, and the distance from the pivot shaft to the rotation output shaft of the electric motor is 1/5 or less of the distance from the pivot shaft to the rear axle shaft and is within the range of 15 cm to 30 cm .

The present invention was made against the background of the above-mentioned circumstances, and aims to provide an electric motorcycle with a new structure that makes it easier to centralize mass and optimize weight distribution compared to conventional in-wheel type electric motors, while also improving the road-following ability of the rear tire, thereby improving handling stability.

The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is merely an example, and may be combined with one another as appropriate. The multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various alternative embodiments may be realized.

The first aspect of the present invention is an electric motorcycle in which a front wheel and a rear wheel are mounted on the front and rear of a body frame, and a driving force is applied to the rear wheel by an electric motor as a driving source. The rear swing arm extending rearward from the body frame is attached so as to be swingable around a pivot shaft, and the rear wheel is rotatably supported by a rear axle shaft attached to the rear end portion of the rear swing arm, while the electric motor is fixedly disposed and supported relative to the rear swing arm, positioned forward of the pivot shaft of the rear swing arm with the rotary output shaft facing in the vehicle width direction.

In the electric motorcycle according to this aspect, the electric motor is not arranged on only the left or right side of the wheel as in the in-wheel type, but can be arranged in a position that ensures a good left and right weight balance in the motorcycle. Moreover, since the electric motor is arranged in the rear swing arm, located in front of the pivot shaft opposite the rear wheel, it is possible to improve the weight balance on both the front and rear sides of the body of the rear swing arm, with the pivot shaft as the swing center, thereby improving the swinging movement of the swing arm and reducing or avoiding uneven load on the rear wheel side in the front-to-rear direction of the body, thereby centralizing and optimizing the mass of the entire motorcycle.

In addition, by supporting both the rear wheel and the electric motor in a fixed manner by the rear swing arm, the length of the drive force transmission path from the electric motor to the rear wheel can be kept constant. This ensures that the suspension reduces the impact on the rear wheel, while avoiding changes in the length of the drive force transmission path that accompanies the suspension stroke, making it possible to simplify the structure of the drive force transmission system for the rear wheel via the electric motor and stabilize the transmitted drive force.

In this embodiment, it is preferable that the distance between the pivot shaft and the rotary output shaft of the electric motor in the longitudinal direction of the body is smaller than the distance between the pivot shaft and the axle of the rear wheels, thereby reducing the travel distance of the electric motor, which is a heavy object, that occurs when the rear swingarm swings, and further stabilizing the position of the center of gravity.
Furthermore, in the electric motorcycle according to this aspect, the driving force transmission mechanism that transmits the rotational driving force of the electric motor, whose rotation output shaft is oriented horizontally, to the rear wheel, which is the driving wheel, can be realized with a lighter weight and simpler structure than when a drive shaft or the like is used, and maintenance is also easier.
Furthermore, in the electric motorcycle according to this aspect, while ensuring the amount of rear wheel suspension stroke allowable in association with the swinging of the rear swingarm, it is possible to reduce the amount of movement of the electric motor associated with the swinging of the rear swingarm. As a result, it is possible to reduce mass displacement associated with movement of the electric motor while driving, thereby contributing to further improving handling stability.

In a second aspect of the present invention, in the electric motorcycle according to the first aspect, a battery for supplying power to the electric motor is mounted on the body frame, and at least one of the battery and the electric motor is removable, and a number of removable batteries and/or electric motors with different performance levels are prepared in advance, and the battery and/or the electric motor can be selected from the number of batteries and/or the electric motors and attached.

According to this aspect, it is possible to efficiently provide an electric motorcycle with highly suitable performance according to the application, required characteristics, user preferences, etc. For example, when the main purpose is to go around the neighborhood such as shopping, a small capacity battery and a small output electric motor can be combined to achieve light weight and easy handling performance, when the main purpose is to use it as a children's playground equipment, an even smaller capacity battery and a small output electric motor can be combined, while when emphasis is placed on sportiness, a small capacity battery and a large output electric motor can be combined to achieve high maneuverability such as turning and high output, and when the main purpose is long distance riding, a large capacity battery and a small to medium output electric motor can be combined.

A third aspect of the present invention is the electric motorcycle according to the first or second aspect, wherein a space above the pivot shaft and/or the electric motor in the body frame is used as a space for arranging other members, and at least one of a rear monoshock that suspends the rear swing arm from the body frame, a battery for supplying power to the electric motor, and an electrical system control device are disposed in the space for arranging other members.

In the electric motorcycle according to this embodiment, by locating the electric motor further forward in the body than the pivot shaft, it is possible to secure a relatively large space above the electric motor and the pivot shaft, and by effectively utilizing this space, it is possible to secure the installation space for components that require a relatively large installation space, such as the rear monoshock, battery, and electrical control device. Note that the rear monoshock, battery, and electrical control device can be installed using the installation space for other components in this embodiment, and it is not necessary to install them entirely within that installation space.

A fourth aspect of the present invention is an electric motorcycle according to any one of the first to third aspects, wherein the centers of gravity of the electric motor and a battery for supplying power to the electric motor are located on a center in a vehicle width direction connecting tread centers of the front wheel and the rear wheel.

In the electric motorcycle according to this embodiment, the center of gravity of the electric motor and battery, which tend to be particularly heavy, is located at the center of the body, thereby improving the running stability of the vehicle. In addition, in the electric motorcycle according to this embodiment, the electric motor located in front of the rear swing arm moves in a generally vertical direction around the pivot shaft, so it is possible to place the battery sufficiently close to the front side of the electric motor while ensuring space for the electric motor to move as the rear swing arm swings. Therefore, it is possible to place the electric motor and battery, which are relatively heavy, close to each other between the front and rear wheels, which allows for centralization of mass, and as a result, it is possible to improve the dynamic characteristics of the motorcycle, for example, to realize smooth behavior with little reaction when steering or braking.

In an electric motorcycle constructed according to the present invention, the weight balance of the rear swing arm, which has a pivot shaft as its center of rotation, can be improved on both the front and rear of the body, improving the operability of the swing arm and the rear wheel suspension, while reducing or avoiding uneven load on the rear wheel side in the front-to-rear direction of the body, and centralizing and optimizing the mass of the entire motorcycle.

In addition, by supporting both the rear wheel and the electric motor in a fixed manner via the rear swing arm, it is possible to ensure that the suspension can reduce the impact of shock on the rear wheel while avoiding changes in the length of the driving force transmission path that accompanies the suspension stroke, making it possible to simplify the structure of the driving force transmission system for the rear wheels via the electric motor, stabilize the transmitted driving force, and steadily achieve excellent transmission efficiency.

1 is a schematic side view showing a main structure of an electric motorcycle according to an embodiment of the present invention; FIG. 2 is a schematic plan view showing a rear swing arm and other components constituting the electric motorcycle shown in FIG. 1 . FIG. 11 is a schematic side view showing a main structure of an electric motorcycle according to another embodiment of the present invention. FIG. 13 is a schematic side view showing a main structure of an electric motorcycle according to still another embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. First, FIG. 1 shows the overall schematic structure of a straddle-type electric motorcycle 10 as one embodiment of the present invention. In FIG. 1, in order to clearly show the features of the present invention, lights and driving safety parts including headlights, rear lights, and turn signals, decorative and protective covers, riding devices such as seats and steps, driving operation devices such as front and rear brakes and accelerators, electrical and mechanical wires, wire harnesses, cables, etc. are omitted. However, these are equipped in various known ways, and a person skilled in the art would be able to implement the present invention without any problems even if the illustrations and explanations are omitted. In the following description, the front-rear direction, left-right direction (width direction), and up-down direction generally refer to the front-rear direction, left-right direction (width direction), and up-down direction of the motorcycle 10.

More specifically, the motorcycle 10 of this embodiment has a body frame 12 formed from a rigid material such as metal or fiber-reinforced resin, and a front wheel 14, which is a driven wheel, is attached to the front of the body frame 12, and a rear wheel 16, which is a driving wheel, is attached to the rear of the body frame 12. The front wheel 14 and the rear wheel 16 are supported rotatably around axles 18, 20 that extend in the vehicle width direction.

The front wheels 14 may be rigidly supported on the body frame 12 without a suspension mechanism, but in this embodiment, the front wheels 14 are supported on the body frame 12 via a publicly known type of front suspension 22. Specifically, for example, an inverted telescoping front suspension 22 is attached to a steering column that is rotatable relative to a head pipe 24 at the front end of the body frame 12, and the axle 18 of the front wheels 14 is supported at the lower end of the front suspension 22, straddling the left and right inner tubes. This sets a predetermined caster angle and trail for the front wheels 14.

The steering column is also fitted with a handlebar 25 that extends to the left and right, and handle grips are provided on both the left and right ends of the handlebar 25. An accelerator, left and right brakes, etc. are attached to the handlebar 25, but as mentioned above, illustrations and detailed explanations are omitted.

Furthermore, although the frame structure of the present invention is not limited, the body frame 12 of this embodiment has a single, double or semi-double type cradle frame structure, and as shown in the side view of FIG. 1, has a central space 32 surrounded by an upper frame 26 and a down frame 28 extending rearward from the head pipe 24, and a pivot frame 30 connecting the rear ends of the upper frame 26 and the down frame 28 to each other. An electric motor 34 and a battery 36 are disposed in this central space 32.

In other words, the motorcycle 10 of this embodiment does not have an internal combustion engine, and travels by transmitting the driving force generated by the electric motor 34 to the rear wheel 16 to rotate it. In addition, the electric energy that operates the electric motor 34 is supplied from the battery 36.

The electric motor 34 and the battery 36 can be of various known types depending on the performance required of the motorcycle. For example, the electric motor 34 is generally an induction type three-phase or single-phase AC motor, but it is also possible to use an AC motor or a DC motor using a permanent magnet. The battery 36 can be anything that can store DC power, and generally lithium-ion batteries or nickel-metal hydride batteries are used, but it is also possible to use lead batteries, capacitors, fuel cells, etc., or to use a combination of multiple types of these. Depending on the electric motor 34 to be combined, it is also possible to use a low-voltage type of 6 to 60 V or a high-voltage type reaching several hundred volts.

In addition, an electrical control device 38 is employed that includes an inverter, converter, etc. for controlling the power supply to the electric motor 34 and for using the regenerative power of the electric motor 34 to charge the battery 36 as needed, depending on the electric motor 34 and battery 36 used. Such an electrical control device 38 can be divided into multiple devices with different functions, etc., or can be integrated into the battery 36 and electric motor 34 and their housings, etc.

Note that a power regeneration mechanism can be adopted as necessary, and the specific form of the power system is not limited in the present invention. In addition, since the amount of heat generated by the electric motor 34, battery 36, and electrical control device 38 can be a problem depending on the output, capacity, and usage conditions, a cooling mechanism using air, water, oil, etc. can be adopted as necessary.

The body frame 12 further includes a seat frame 40 that extends rearward from the upper frame 26. The pivot frames 30, located rearward of the down frame 28, are arranged in a pair on the left and right sides at a predetermined distance apart, and a rear swing arm 42 is mounted to be swingable around the central axis of a pivot shaft 47 that is attached across the left and right pivot frames 30, 30.

The rear swing arm 42 is made of a highly rigid material such as metal or fiber-reinforced resin, just like the body frame 12, and as shown in FIG. 2, is integrally provided with a cylindrical pivot pipe 44 extending left and right, and a pair of left and right rear arms 46, 46 extending rearward from the pivot pipe 44. The pivot shaft 47 is inserted into the pivot pipe 44 and connected via a bearing, so that the rear swing arm 42 is attached to the body frame 12 so as to be swingable around the pivot axis (the central axis of the pivot pipe 44 and pivot shaft 47).

The rear axle shaft 20 of the rear wheel 16 is supported near the rear ends of the rear arms 46, 46 of the rear swingarm 42 via a chain puller block or the like, and the rear wheel 16 is rotatably attached to the rear axle shaft 20. A rear suspension 48 is attached between the rear swingarm 42 and the body frame 12. The specific shape and structure of the rear swingarm 42 and the specific structure of the rear suspension 48 are not limited. For example, in this embodiment, left and right spring-equipped shock absorbers are attached between the rear ends of the left and right rear arms 46, 46 of the rear swingarm 42 and the left and right seat frames 40, 40 arranged above them, forming a twin-shock type rear suspension 48.

The electric motor 34 is fixedly attached to the rear swing arm 42, located in front of and opposite the rear arms 46, 46 in the fore-aft direction, across the pivot pipe 44. The electric motor 34 is attached to the rear swing arm 42 with its rotary output shaft 35 extending in the left-right direction.

The specific method of fixing the electric motor 34 to the rear swing arm 42 is not limited, but for example, in this embodiment, a bracket 50 is provided so as to protrude forward from the outer circumferential surface of the pivot pipe 44, and the housing of the electric motor 34 is detachably attached to the bracket 50 with bolts or the like, thereby mounting the electric motor 34 to the rear swing arm 42. In short, the electric motor 34 is not directly supported by the body frame 12, but is attached to the rear swing arm 42, and is thereby supported by the body frame 12 via the rear swing arm 42.

The electric motor 34 has a motor center of gravity 52 set on a body centerline (center in the vehicle width direction) 54 that connects the tread width centers of the front and rear wheels 14 and 16 and extends in the fore-aft direction. The rotary output shaft 35 of the electric motor 34 protrudes only on one side in the vehicle width direction, and a drive sprocket 56 is fixed to it. A drive chain 60 is stretched between the driven sprocket 58 attached to the rear wheel 16. In this embodiment, the vertical positions of the rotary output shaft 35 of the electric motor 34 and therefore the drive sprocket 56 are set so that the pivot shaft is approximately located between the upper and lower chains 60 between the front and rear sprockets 56, 58, but this is not limited to this embodiment.

As a result, when the electric motor 34 is operated to rotate the drive sprocket 56, the rotational driving force is transmitted to the driven sprocket 58 via the roller chain 60, driving the rear wheel 16. Note that in this embodiment, following the example of a conventional internal combustion engine type motorcycle, the drive side and driven side sprockets 56, 58 and the chain 60 are provided on the left side of the vehicle, but since this is an electric type and there is no need to install an exhaust pipe, etc., the sprockets 56, 58 and the chain 60 may be provided on the right side of the vehicle, or it is also possible to provide them on both the left and right sides of the vehicle.

In addition, the mechanism for transmitting the rotational drive force of the electric motor 34 to the rear wheel 16 can use a pulley and belt instead of the sprocket and chain shown in the example. As such a pulley and belt, a flat belt or a timing belt (a toothed belt) can also be used.

Here, both the electric motor 34 and the rear wheel 16 are fixedly attached and supported by the rear swing arm 42. Therefore, even if the rear swing arm 42 swings due to the operation of the rear suspension 48, the distance between the drive sprocket 56 on the electric motor 34 side and the driven sprocket 58 on the rear wheel 16 side is kept constant. Therefore, the tension of the roller chain 60 stretched between the two sprockets 56, 58 is also kept constant, making it possible to set an appropriate tension for the roller chain 60. As a result, for example, unintentional disengagement of the roller chain 60 from the sprockets 56, 58 is effectively prevented, and it is also possible to suppress the mechanical operating resistance of the driving force transmission system including the roller chain 60 and each sprocket 56, 58, thereby improving and stabilizing the transmission efficiency of the driving force.

In addition, when the rear swing arm 42 swings in accordance with the suspension stroke of the rear wheel 16, the position of the electric motor 34 also changes. However, the distance L1 from the pivot shaft 47, which is the swing center, to the center of gravity (central axis) 52 of the electric motor 34 is sufficiently small compared to the distance L2 from the pivot shaft 47 to the axle 20 of the rear wheel 16. This makes it possible to stabilize the center of gravity position by minimizing the amount of movement of the electric motor 34 associated with the swing of the rear swing arm 42 while ensuring the suspension stroke of the rear wheel 16. The distance L2 from the pivot shaft 47 to the axle 20 of the rear wheel 16 varies depending on the size of the body frame 12 and the rear wheel 16, and can be set appropriately taking into account the use of the motorcycle 10, but the distance L1 from the pivot shaft 47 to the center of gravity (central axis) 52 of the electric motor 34 is preferably set to 1/5 of L2 or less and within the range of L1≦30 cm, thereby making it possible to keep the amount of movement of the electric motor 34 associated with the swing of the rear swing arm 42 sufficiently small.

On the other hand, by setting the distance L1 from the pivot shaft 47 to the center of gravity (central axis) 52 of the electric motor 34 to 15 cm or more, the center of mass of the electric motor 34 can be proactively set forward of the body, centralizing the mass and thereby improving handling stability.

The electric motor 34 may be positioned around the pivot pipe 44 so that its central axis is located forward of the pivot shaft 47. However, considering the weight balance with the rear arm 46 extending rearward from the pivot pipe 44, it is preferable that the electric motor 34 be positioned approximately on a line extending forward from the pivot pipe 44. Preferably, the central axis of the electric motor 34 is positioned within a range of 45 degrees above and below the horizontal line extending forward from the pivot shaft 47 around the pivot shaft 47, and more preferably, the central axis of the electric motor 34 is positioned within a range of 30 degrees above and below the pivot shaft 47.

In this way, by arranging the electric motor 34 further forward of the pivot shaft 47, the front-rear balance of the rear swing arm 42 that swings around the pivot shaft 47 is improved, which also contributes to improving the operability of the rear swing arm 42. In addition, because the electric motor 34 is arranged close to the pivot shaft 47, the inertial mass or rotational moment associated with the swing of the rear swing arm 42 can be reduced compared to conventional in-wheel motors, and the swing of the rear swing arm 42 and thus the suspension stroke of the rear wheel 16 can be improved to improve maneuverability.

In addition, in this embodiment, the electric motor 34 is positioned close to the front of the pivot shaft 47 located at the rear lower part of the body frame 12, so that a relatively large space can be easily secured in front of the electric motor 34 and diagonally above the front. Therefore, while it is possible to use such space as storage space for luggage, etc., it can also be effectively used as installation space for the battery 36, which has a relatively large volume and mass.

The mass of the battery 36 is relatively large, so its position on the body frame 12 has a large effect on the characteristics of the motorcycle 10. However, as described above, a large space can be secured in front of and above the electric motor 34, so the position of the battery 36 can be set with a large degree of freedom. For example, by positioning the battery 36 at the bottom of the space, it is possible to improve the ease of handling of the motorcycle 10 and improve the handling stability at low speeds, while by positioning the battery 36 at the top of the space, it is possible to improve the cornering characteristics, including the turning performance, and handling stability of the motorcycle 10 at relatively high speeds.

Furthermore, since it is easy to secure a large space above the electric motor 34, the space above the electric motor 34 and the pivot (pivot pipe) 44 can be used as the space for arranging other members. Specifically, for example, as shown in FIG. 3, the spatial area above at least one of the electric motor 34 and the pivot 44 in the body frame 12 can be used as the space for arranging the rear suspension 62. Incidentally, the rear suspension 62 shown in FIG. 3 is a monoshock type in which a spring-equipped shock absorber is arranged between a lower bracket part 64 provided behind the pivot pipe 44 in the rear swing arm 42 and an upper bracket part 66 provided above the electric motor 34 in the body frame 12.

As mentioned above, the characteristics of the motorcycle 10 can be tuned by setting the mass center of the battery 36, but it is preferable that the battery 36 be detachable from the body frame 12. This allows the battery 36 to be removed and charged, so that when the stored charge of the battery 36 becomes low, it can be replaced with a previously charged battery 36, allowing the motorcycle 10 to be used continuously regardless of the time required for charging. It also makes it possible to use batteries 36 with different capacities and weights as needed, or to sell them selectively with only one installed.

Furthermore, it is also possible to selectively mount batteries 36 and electric motors 34 with different performance (e.g., capacity, output, type, etc.) and to prepare multiple types in advance, so that the designer or user can select an appropriate combination from among them, taking into consideration the use and required performance of the motorcycle 10, and mount them on the body frame 12. For example, when the motorcycle is intended for use in a short distance where relatively frequent start-and-stop operations are repeated or for use in a small playground, a lightweight capacitor can be used as the battery and charged with the regenerative power of the electric motor, making it easier to achieve a smaller size and lighter weight than a lithium-ion type, and it is also possible to realize a motorcycle that requires a lighter weight than a four-wheeled vehicle. In that case, the electric motor and the capacitor can be fixedly mounted on the rear swingarm. Furthermore, both the electric motor and the capacitor can be positioned forward of the pivot shaft on the rear swingarm. As a result, it is possible to further optimize the weight balance of the rear swingarm and simplify the structure including the frame. Even in such cases, it is desirable to make it possible to attach, detach, and replace electric motors and batteries such as capacitors.

The battery 36 may be selectively attached to multiple positions on the body frame 12. Note that selective attachment to multiple positions may be achieved by preparing different brackets. On the other hand, the electric motor 34 may also be selectively attached to the rear swing arm 42 by changing the direction or distance of separation from the pivot pipe 44 of the rear swing arm 42. In this case, too, the attachment position of the electric motor 34 can be changed by, for example, changing the bracket used.

Furthermore, the frame type employed in the present invention is not limited, and the mounting position and mounting structure of the battery 36 relative to the body frame can be appropriately changed depending on the frame type. Specifically, in addition to the cradle frame as exemplified in the above embodiment, diamond frames or backbone frames without undertubes, trellis frames with a truss structure, twin spar or twin tube frames, monocoque frames, etc. can be appropriately employed, and even if they have pivot pipes, a body frame structure that is almost like a main frameless structure can be employed by fixing the necessary subframe to the housing of the battery 36, for example, using the housing of the battery 36 itself as a rigid frame.

As a specific example, as shown in FIG. 4, a body frame 74 with a backbone frame structure can be used in which the main tube 70 extending rearward from the head pipe 24 and the pivot frame 72 are integrally formed without an undertube. In conventional backbone frames, the internal combustion engine is supported by being suspended from the main tube 70, but the present invention does not require an internal combustion engine, and the electric motor 34 as a drive source is also attached to the tip of the rear swing arm 42, so a relatively large space can be secured below the main tube 70. Therefore, as shown in FIG. 4, it is also easy to arrange and support the battery 76 in a suspended state from the main tube 70.

In addition, although not listed individually, the present invention can be embodied in various forms with various changes and modifications based on the knowledge of a person skilled in the art. For example, the electric motor 34 and the battery 36 may be provided with a cooling mechanism such as air cooling, water cooling, or oil cooling in their housings. The electric motor 34 may be provided with a gear train or a speed change mechanism for adjusting the rotation speed integrally in its housing, in which case the shaft that finally outputs the rotational driving force via the gear train or speed change mechanism may be the rotation output shaft. The electric motor 34, the battery 36, 76, the electric control device 38, etc. may be fixedly supported on the rear swing arm 42 or the body frame 12, 74 via vibration isolating rubber or the like.
Furthermore, the present invention originally includes each of the inventions described in (i) to (vi) below, and the configurations and effects thereof will be described below.
The present invention relates to
(i) An electric motorcycle having a front wheel and a rear wheel mounted on the front and rear of a body frame, and an electric motor as a drive source for applying a driving force to the rear wheel, wherein a rear swing arm extending rearward from the body frame is attached so as to be swingable about a pivot shaft, and the rear wheel is rotatably supported by a rear axle shaft attached to a rear end portion of the rear swing arm, while the electric motor is positioned forward of the pivot shaft of the rear swing arm with its rotary output shaft facing in the vehicle width direction, and is fixedly disposed and supported relative to the rear swing arm;
(ii) The electric motorcycle according to (i), wherein a battery for supplying power to the electric motor is mounted on the body frame, and at least one of the battery and the electric motor is detachable, and a plurality of detachable batteries and/or electric motors with different performances are prepared in advance, and the battery and/or the electric motor can be selected from the plurality and attached.
(iii) The electric motorcycle according to (i) or (ii), in which a drive side sprocket or pulley is attached to the rotary output shaft of the electric motor, while a driven side sprocket or pulley is attached to the rear wheel, and driving force is transmitted from the drive side to the driven side via a chain or belt.
(iv) The electric motorcycle according to any one of (i) to (iii), wherein, in the rear swing arm, a distance from the pivot shaft to the rotation output shaft of the electric motor is ⅕ or less and 30 cm or less of a distance from the pivot shaft to the rear axle shaft.
(v) The electric motorcycle according to any one of (i) to (iv), wherein a space above the pivot shaft and/or the electric motor in the body frame is used as a space for arranging other members, and at least one of a rear monoshock that suspends the rear swing arm from the body frame, a battery for supplying power to the electric motor, and an electrical system control device are arranged in the space for arranging other members.
(vi) The electric motorcycle according to any one of (i) to (v), wherein the positions of the centers of gravity of the electric motor and the battery for supplying power to the electric motor are set on a center in a vehicle width direction connecting tread centers of the front wheel and the rear wheel.
This includes inventions relating to.
In the invention described in (i) above, the electric motor is not disposed on only one side of the wheel as in the in-wheel type, but can be disposed at a position where the left and right weight balance of the motorcycle can be secured well. Moreover, since the electric motor is disposed in the rear swingarm at the front opposite the rear wheel across the pivot shaft, the weight balance of the rear swingarm on both the front and rear sides of the body can be improved with the pivot shaft as the swing center, improving the swinging movement of the swingarm and reducing or avoiding the offset load on the rear wheel side in the front-rear direction of the body, thereby concentrating and optimizing the mass of the motorcycle as a whole. In addition, since both the rear wheel and the electric motor are fixedly supported by the rear swingarm, the distance of the drive force transmission path from the electric motor to the rear wheel can be maintained constant. Therefore, while securing the shock reduction effect of the suspension on the rear wheel, it is possible to avoid the change in the length of the drive force transmission path due to the suspension stroke, and it is possible to simplify the structure of the drive force transmission system of the rear wheel by the electric motor and to stabilize the transmitted drive force. In this embodiment, it is preferable that the distance between the pivot shaft and the rotary output shaft of the electric motor in the longitudinal direction of the body is smaller than the distance between the pivot shaft and the axle of the rear wheels, thereby reducing the travel distance of the electric motor, which is a heavy object, that occurs when the rear swingarm swings, and further stabilizing the position of the center of gravity.
The invention described in (ii) above makes it possible to efficiently provide an electric motorcycle with highly adaptable performance according to the application, required characteristics, user preferences, etc. To give a specific example, when the main purpose is to go around the neighborhood such as shopping, a small capacity battery and a small output electric motor are combined to achieve light weight and easy handling performance, when the main purpose is to use it as a children's playground equipment, an even smaller capacity battery and a small output electric motor are combined, while when emphasis is placed on sportiness, a small capacity battery and a large output electric motor are combined to achieve high maneuverability such as turning and high output, and when the main purpose is long distance riding, a large capacity battery and a small to medium output electric motor are combined.
In the invention described in (iii) above, the driving force transmission mechanism that transmits the rotational driving force of an electric motor with its rotating output shaft oriented horizontally to the rear wheels, which are the driving wheels, can be realized with a lighter weight and simpler structure than when a drive shaft or the like is used, and maintenance is also easier.
In the invention described in (iv) above, while ensuring the amount of rear wheel suspension stroke allowable in association with the swinging of the rear swing arm, it is possible to reduce the amount of movement of the electric motor associated with the swinging of the rear swing arm. As a result, it is possible to reduce mass displacement associated with the movement of the electric motor while driving, contributing to further improving handling stability.
In the invention described in (v) above, by locating the electric motor further forward of the pivot shaft, it is possible to secure a relatively large space above the electric motor and the pivot shaft, and by effectively utilizing this space, it is possible to secure space for arranging components that require a relatively large amount of space, such as the rear monoshock, battery, and electrical control device. Note that it is sufficient for the rear monoshock, battery, and electrical control device to be arranged using the space for arranging other components in this embodiment, and it is not necessary to arrange them entirely within that space.
In the invention described in (vi) above, the center of gravity of the electric motor and the battery, which tend to be particularly heavy, is located at the body center, thereby improving the running stability of the vehicle. In addition, in the electric motorcycle of this aspect, the moving direction of the electric motor located in front of the rear swing arm is approximately vertical around the pivot shaft, so that it is possible to arrange the battery sufficiently close to the front side of the electric motor while ensuring a movement space for the electric motor accompanying the swing of the rear swing arm. Therefore, it is possible to arrange the electric motor and the battery, which are relatively heavy, close to each other between the front and rear wheels, and as a result of centralization of the mass, it is possible to improve the dynamic characteristics of the motorcycle, for example, to realize a straightforward behavior with less reaction during steering and braking.

10 Motorcycle 12 Body frame 14 Front wheel 16 Rear wheel 18 Axle (front wheel)
20 Axle (rear wheel)
22 Front suspension 24 Head pipe 25 Handlebar 26 Upper frame 28 Down frame 30 Pivot frame 32 Central space 34 Electric motor 35 Rotation output shaft 36 Battery 38 Electrical control device 40 Seat frame 42 Rear swing arm 44 Pivot pipe 46 Rear arm 47 Pivot shaft 48 Rear suspension 50 Bracket 52 Motor center of gravity 54 Body center line 56 Drive sprocket 58 Driven sprocket 60 Chain 62 Rear suspension 64 Lower bracket portion 66 Upper bracket portion 70 Main tube 72 Pivot frame 74 Body frame 76 Battery

Claims (4)

An electric motorcycle having a front wheel and a rear wheel attached to the front and rear of a body frame, and an electric motor as a drive source to apply a driving force to the rear wheel,
A rear swing arm extending rearward from the body frame is attached so as to be swingable about a pivot shaft,
The rear wheel is rotatably supported by a rear axle shaft attached to a rear end portion of the rear swing arm,
the electric motor is positioned forward of the pivot shaft of the rear swing arm with a rotation output shaft facing in a vehicle width direction, and is fixedly disposed and supported relative to the rear swing arm,
A drive sprocket is attached to the rotary output shaft of the electric motor, and a driven sprocket is attached to the rear wheel, so that a driving force is transmitted from the drive side to the driven side via a chain.
The drive sprocket and the driven sprocket are disposed opposite each other across the pivot shaft, and the chain stretched between the sprockets is positioned above and below the pivot shaft,
a distance from the pivot shaft to the rotation output shaft of the electric motor is 1/5 or less of a distance from the pivot shaft to the rear axle shaft, and is within a range of 15 cm to 30 cm . A battery for supplying power to the electric motor is mounted on the body frame,
2. The electric motorcycle according to claim 1, wherein at least one of the battery and the electric motor is detachable, and a plurality of detachable batteries and/or electric motors with different performances are prepared in advance, and the battery and/or the electric motor can be selected from the plurality of batteries and/or the electric motor and attached. 3. The electric motorcycle according to claim 1 or 2, wherein a space above the pivot shaft and/or the electric motor in the body frame is used as a space for arranging other members, and at least one of a rear monoshock that suspends the rear swing arm from the body frame, a battery for supplying power to the electric motor, and an electrical system control device are arranged in the space for arranging other members. The electric motorcycle according to any one of claims 1 to 3 , wherein the centers of gravity of the electric motor and a battery for supplying power to the electric motor are set on a center in a vehicle width direction connecting tread centers of the front wheel and the rear wheel.

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