Electric motorcycle

Abstract

To provide an electric motorcycle of a novel structure that is able to facilitate the optimization of mass concentration and weight distribution, improve the road-surface followability of a rear tire as compared with that of a conventional in-wheel motor, and also improve steering stability.SOLUTION: In an electric motorcycle 10, an electric motor 34 that applies a rotational driving force to a rear wheel 16 is disposed further forward than a pivot shaft 47 of a rear swing arm 42, with a rotation output shaft 35 directed in a vehicle width direction, and the electric motor 34 is fixed to and supported by the rear swing arm 42.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric motorcycle in which an electric motor is used as a drive source to apply a driving force to a rear wheel, and more particularly to an electric motorcycle equipped with a rear swing arm having a novel specific structure. [Background technology]

[0002] 2. Description of the Related Art 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 motor-driven bicycles) that are equipped with a drive source.

[0003] Incidentally, most electric motorcycles proposed so far have adopted an in-wheel type electric motor that directly drives the rear wheel axle, as described in Patent Document 1 (JP 2011-152901 A).

[0004] However, in an electric motorcycle that employs an in-wheel type electric motor, the electric motor is disposed only on the left or right side of the rear wheel, which makes it difficult to achieve a lateral weight balance. As is well known, in a motorcycle that has one front wheel and one rear wheel, lateral balance is important for ensuring driving stability and course keeping, and particularly in lightweight motorcycles and motorcycles for sports or leisure use, even stricter weight balance is required.

[0005] Therefore, as described in the above-mentioned Patent Document 1, it is also 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 disposing the electric motor only on one side of the rear wheels by setting the center of gravity of the 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 that 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.

[0006] In addition, since the electric motor, which is a heavy object, is disposed near the rear end of the vehicle in the fore-and-aft direction, the weight distribution in the fore-and-aft direction of the motorcycle, which places great importance on weight balance, is likely to deviate significantly from the ideal load distribution in the fore-and-aft direction, which can lead to problems such as poor straight-line stability and poor handling when cornering.

[0007] 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 that is pivotable around a pivot shaft relative to the body frame. This means that the distance from the pivot shaft to the electric motor is large, and the moment of inertia around the pivot shaft is inevitably large. This means that the rear tire is likely to be poorly able to follow uneven road surfaces, which can have a negative impact on ride comfort and handling stability. [Prior art documents] [Patent documents]

[0008] 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 its rotation output shaft facing in the vehicle width direction, and is fixedly disposed and supported relative to the rear swing arm. a drive side sprocket is attached to the rotary output shaft of the electric motor and a driven side sprocket is attached to the rear wheel, and a 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 with the pivot shaft in between, the chain stretched between the sprockets is located above and below the pivot shaft, and the distance from the pivot shaft to the rotary 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 a range of 15 cm to 30 cm. The electric motorcycle is characterized by having a Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made against the background described above, and has an object to provide an electric motorcycle with a new structure which makes it easier to centralize mass and optimize weight distribution, and which also improves the road-following ability of the rear tire, thereby enabling improved handling stability, compared to a conventional electric motorcycle that uses an in-wheel type electric motor. [Means for solving the problem]

[0010] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely illustrative and may be combined with one another as appropriate, and 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 other embodiments may be realized.

[0011] 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 used as a drive source to apply driving force to the rear wheel, wherein a rear swingarm 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 swingarm, while the electric motor is fixedly disposed and supported relative to the rear swingarm, positioned forward of the pivot shaft of the rear swingarm, with its rotary output shaft facing in the vehicle width direction.

[0012] In the electric motorcycle according to this aspect, the electric motor is not disposed on only one side of the wheel as in the in-wheel type, but can be disposed in a position that ensures a good left-right weight balance in the motorcycle. Moreover, since the electric motor is disposed in the rear swingarm, at the front side opposite the rear wheel across the pivot shaft, the weight balance on both the front and rear sides of the body of the rear swingarm about the pivot shaft can be improved, improving the swinging movement of the swingarm and reducing or avoiding unbalanced load on the rear wheel side in the front-rear direction of the body, thereby concentrating and optimizing the mass of the entire motorcycle.

[0013] In addition, since both the rear wheel and the electric motor are fixedly supported 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, which ensures the shock mitigation effect of the suspension on the rear wheel and prevents changes in the length of the drive force transmission path that accompany the suspension stroke, making it possible to simplify the structure of the drive force transmission system to the rear wheels by the electric motor and stabilize the transmitted drive force.

[0014] 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.

[0015] 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 plurality of removable 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.

[0016] 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 are combined to achieve light weight and easy handling, 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.

[0021] The present invention three The first aspect is or No. two In the electric motorcycle according to the embodiment, in the body frame, a space above the pivot shaft and / or the electric motor 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.

[0022] In the electric motorcycle according to this aspect, 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 installation space for components that require a relatively large installation 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 installed using the installation space for other components in this aspect, and it is not necessary to install them entirely within that installation space.

[0023] The present invention four The above first to fourth aspects are three wherein the positions of 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 the tread centers of the front wheel and the rear wheel.

[0024] In the electric motorcycle according to this aspect, 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 according to 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. Effect of the Invention

[0025] In an electric motorcycle constructed according to the present invention, the weight balance on both the front and rear of the body of the rear swing arm, which swings around the pivot shaft, can be improved, improving the operability of the swing arm and the operability of the rear wheel suspension. It is also possible to reduce or avoid unbalanced load on the rear wheel side in the fore-and-aft direction of the body, and centralizing and optimizing the mass of the entire motorcycle.

[0026] Furthermore, by fixedly supporting both the rear wheel and the electric motor by the rear swing arm, it is possible to ensure the shock reduction effect of the suspension on the rear wheel while avoiding changes in the length of the driving force transmission path that accompanies the suspension stroke, thereby 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. [Brief description of the drawings]

[0027] [Figure 1] 1 is a schematic side view showing a main structure of an electric motorcycle according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic plan view showing a rear swing arm and other components constituting the electric motorcycle shown in FIG. 1. [Diagram 3] FIG. 11 is a schematic side view showing a main structure of an electric motorcycle according to another embodiment of the present invention. [Figure 4] FIG. 13 is a schematic side view showing a main structure of an electric motorcycle according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, Fig. 1 shows an overall schematic structure of a saddle-type electric motorcycle 10 as an embodiment of the present invention. In Fig. 1, in order to clearly show the features of the present invention, lights including a headlight, a rear light, and a direction indicator, driving safety parts, decorative and protective covers, riding devices such as a seat and a step, driving operation devices such as a front and rear brake device and an accelerator, electrical and mechanical wires, wire harnesses, cables, etc. are omitted. However, these are equipped in various known forms, and a person skilled in the art would be able to carry out the present invention without any problems even if the illustrations and explanations are omitted. In the following description, the front-rear direction, the left-right direction (width direction), and the up-down direction basically refer to the front-rear direction, the left-right direction (width direction), and the up-down direction of the motorcycle 10.

[0029] 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 drive wheel, is attached to the rear of the body frame 12. The front wheel 14 and rear wheel 16 are supported rotatably around axles 18, 20 that extend in the vehicle width direction.

[0030] 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 known front suspension 22 of any type. Specifically, for example, an inverted telescoping front suspension 22 is mounted by 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 between the left and right inner tubes. This sets a predetermined caster angle and trail for the front wheels 14.

[0031] A handlebar 25 that extends to the left and right is attached to the steering column, 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.

[0032] 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 Figure 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.

[0033] That is, the motorcycle 10 of this embodiment does not include an internal combustion engine, and travels by transmitting driving force generated by the electric motor 34 to the rear wheel 16 to rotate it. In addition, the electric energy for operating the electric motor 34 is supplied from a battery 36.

[0034] Various known types of electric motor 34 and battery 36 can be used depending on the performance required for the motorcycle. For example, an induction type three-phase or single-phase AC motor is generally used for electric motor 34, but an AC motor or DC motor using a permanent magnet can also be used. Also, any battery capable of storing DC power is sufficient for battery 36, and generally lithium-ion batteries or nickel-hydrogen batteries are used, but it is also possible to use lead batteries, capacitors, fuel cells, or the like, or to use a combination of a plurality of these types. 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.

[0035] Also, an electric system control device 38 is employed that includes an inverter, converter, etc. for controlling the power supply to the electric motor 34 and for utilizing the regenerative power of the electric motor 34 to charge the battery 36 as necessary, depending on the electric motor 34 and battery 36 employed. Such an electric system control device 38 can be provided separately as a plurality of devices with different functions, or can be configured by being integrally incorporated into the battery 36 or electric motor 34, or into their housings, etc.

[0036] Note that a power regeneration mechanism or the like 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.

[0037] Furthermore, the body frame 12 includes a seat frame 40 extending rearward from the upper frame 26. The pivot frames 30, located rearward of the down frame 28, are configured as a pair of opposing arrangements spaced a predetermined distance apart on both the left and right sides, and a rear swing arm 42 is mounted to be swingable about the central axis of a pivot shaft 47 by a pivot shaft 47 mounted straddling between the left and right pivot frames 30, 30.

[0038] 2, the rear swing arm 42 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 about the pivot axis (the central axis of the pivot pipe 44 and the pivot shaft 47).

[0039] Further, an axle (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 pulling block or the like as appropriate, so that the rear wheel 16 is rotatably attached. Furthermore, a rear suspension 48 is mounted 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 respective 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, thereby forming a twin-shock type rear suspension 48.

[0040] Meanwhile, the electric motor 34 is disposed and fixedly attached to the rear swing arm 42 at a position in front of and opposite the rear arms 46, 46 in the front-rear direction, with the pivot pipe 44 in between. The electric motor 34 is disposed with its rotary output shaft 35 extending in the left-right direction and attached to the rear swing arm 42.

[0041] Although a specific method for fixing the electric motor 34 to the rear swing arm 42 is not limited, 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 a 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 thereby supported by the body frame 12 via the rear swing arm 42.

[0042] The electric motor 34 has a motor center of gravity 52 set on a body center line (center in the vehicle width direction) 54 that connects the tread width centers of the front wheels 14 and the rear wheels 16 and extends in the front-rear direction. The rotation 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 the rotation output shaft 35. A drive chain 60 is stretched between the driven sprocket 58 attached to the rear wheel 16. Note that in this embodiment, the vertical positions of the rotation output shaft 35 of the electric motor 34 and therefore the drive sprocket 56 are set so that the pivot shaft is located approximately between the upper and lower chains 60 between the front and rear sprockets 56, 58, but the present invention is not limited to this embodiment.

[0043] 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 to drive the rear wheel 16. Note that in this embodiment, the drive and driven sprockets 56, 58 and the chain 60 are provided on the left side of the vehicle, following the example of a conventional internal combustion engine type motorcycle, but because this is an electric type and there is no need to provide an exhaust pipe or the like, 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.

[0044] Also, a pulley and a belt may be used instead of the illustrated sprocket and chain as the transmission mechanism for the rotational drive force of the electric motor 34 to the rear wheel 16. As the pulley and belt, a flat belt or a timing belt (a toothed belt) may also be used.

[0045] 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, unintended disengagement of the roller chain 60 from the sprockets 56, 58 is effectively prevented, and the mechanical operating resistance of the driving force transmission system including the roller chain 60 and the sprockets 56, 58 can be suppressed, thereby improving and stabilizing the transmission efficiency of the driving force.

[0046] Furthermore, the position of the electric motor 34 also changes when the rear swing arm 42 swings in accordance with the suspension stroke of the rear wheel 16. However, since 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 set sufficiently smaller than the distance L2 from the pivot shaft 47 to the axle 20 of the rear wheel 16, it is possible to stabilize the center of gravity position by keeping the amount of movement of the electric motor 34 associated with the swing of the rear swing arm 42 small while ensuring the suspension stroke amount of the rear wheel 16. Note that distance L2 from pivot shaft 47 to axle 20 of rear wheel 16 varies depending on the size of body frame 12 and rear wheel 16, and can be set appropriately taking into consideration the use of motorcycle 10, etc.; however, distance L1 from pivot shaft 47 to center of gravity (central axis) 52 of 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 electric motor 34 associated with the swing of rear swing arm 42 sufficiently small.

[0047] 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 actively set forward of the body, thereby enabling centralization of mass and the resulting improvement of handling stability.

[0048] Also, 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, but considering the weight balance with the rear arm 46 extending rearward from the pivot pipe 44, it is desirable to position the electric motor 34 approximately on a line extending forward from the pivot pipe 44. Preferably, the central axis of the electric motor 34 is located within a range of 45 degrees above and below the pivot shaft 47 with respect to a horizontal line extending forward from the pivot shaft 47, and more preferably, the central axis of the electric motor 34 is located within a range of 30 degrees above and below the pivot shaft 47.

[0049] 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 about 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 a conventional in-wheel motor, and the swing of the rear swing arm 42 and therefore the operability of the suspension stroke of the rear wheel 16 are improved, thereby improving maneuverability, etc.

[0050] Furthermore, in this embodiment, since the electric motor 34 is disposed close to the front of the pivot shaft 47 located at the rear lower part of the body frame 12, a relatively large space can be easily secured in front of the electric motor 34 and diagonally above the front. Therefore, although such a space can be used as a storage space for luggage, for example, it can also be effectively used as a space for arranging the battery 36, which has a relatively large volume and mass.

[0051] Since the mass of the battery 36 is relatively large, its installation position on the body frame 12 has a large effect on the characteristics of the motorcycle 10, but since a large space can be secured in front of and above the electric motor 34 as described above, the position of the battery 36 can be set with a large degree of freedom. Therefore, 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 the handling stability of the motorcycle 10 at relatively high speeds.

[0052] 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 also be used as an arrangement space for 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 also be used as an arrangement space for a rear suspension 62. Incidentally, the rear suspension 62 shown in Fig. 3 is a monoshock type in which a shock absorber with a spring is arranged straddling between a lower bracket portion 64 provided behind the pivot pipe 44 in the rear swing arm 42 and an upper bracket portion 66 provided above the electric motor 34 in the body frame 12.

[0053] As described 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, for example, so that when the stored charge of the battery 36 becomes low, it can be replaced with a pre-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 the product with only one battery installed.

[0054] Furthermore, the battery 36 and the electric motor 34 may be selectively mounted with different performances (for example, capacity, output, type, etc.), and multiple types may be prepared in advance, and the designer or user may 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 is repeated or in a small playground, a lightweight capacitor may be used as the battery and charged with regenerative power from the electric motor, making it easier to achieve a smaller size and lighter weight than a lithium-ion type, and it is possible to realize a motorcycle that is required to be lighter than a four-wheeled vehicle. In that case, the capacitor may be fixedly mounted to the rear swingarm in addition to the electric motor. Furthermore, both the electric motor and the capacitor may be disposed 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 a case, it is desirable to make it possible to detach and replace the electric motor and the battery such as the capacitor in a special manner.

[0055] The battery 36 may be selectively attached to a plurality of positions on the body frame 12. Note that selective attachment to a plurality of positions may be achieved by preparing different brackets. Meanwhile, the electric motor 34 may also be attached to the rear swing arm 42 by selectively changing the direction or distance of separation from the pivot pipe 44 in the rear swing arm 42. In this case as well, the attachment position of the electric motor 34 can be changed by, for example, changing the bracket used.

[0056] 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, a diamond frame or backbone frame without an undertube, a trellis frame with a truss structure, a twin spar or twin tube frame, a monocoque frame, and the like can be appropriately employed, and a body frame structure that has a pivot pipe but is as if it were a main frameless structure can also be employed by fixing a necessary subframe to the housing of the battery 36, for example, using the housing of the battery 36 itself as a rigid frame.

[0057] As a specific example, as shown in Fig. 4, a body frame 74 having a backbone frame structure in which a main tube 70 extending rearward from the head pipe 24 and a pivot frame 72 are integrally provided without an under tube can be adopted. In a conventional backbone frame, an 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 portion of the rear swing arm 42, so that 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 a battery 76 in a suspended state by the main tube 70.

[0058] Although not listed here, 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, within their housings. The electric motor 34 may be provided with a gear train or a speed change mechanism for adjusting the rotation speed, integrated within its housing. In this 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, and the like may be fixedly supported by the rear swing arm 42 or the body frame 12, 74 via vibration-proof rubber or the like. Furthermore, the present invention essentially 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) An electric motorcycle as described in (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 1 / 5 or less and 30 cm or less relative to 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 relative to 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 a position opposite to 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, it is possible to avoid the change in the length of the drive force transmission path due to the suspension stroke while securing the shock mitigation effect of the rear wheel by the suspension, 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 swing of the rear swing arm, it is possible to reduce the amount of movement of the electric motor associated with the swing 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 improvement of handling stability. In the invention described in (v) above, 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 the installation 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 space for the electric motor to move with 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 smooth behavior with less reaction during steering and braking. [Explanation of symbols]

[0059] 10. Motorcycles 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 rpm output shaft 36 Battery 38 Electrical control device 40 Seat frame 42 Rear swingarm 44 Pivot pipe 46 Rear arm 47 Pivot shaft 48 Rear suspension 50 Bracket 52 Motor center of gravity 54 Body centerline 56 Drive sprocket 58 Driven sprocket 60 Chain 62 Rear suspension 64 Lower bracket part 66 Upper bracket part 70 Main Tube 72 Pivot Frame 74 Body Frame 76 Battery

Claims

1. 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.

2. 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. 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.

4. The electric motorcycle according to any one of claims 1 to 3, wherein positions of 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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