29-06-2012, 02:12 PM
HYBRID MOTORCYCLE
HYBRID MOTORCYCLE.pdf (Size: 7.75 MB / Downloads: 517)
ABSTRACT
In recent years, hybrid motor vehicles configured to travel by using a driving force generated by an electric motor in addition to an engine power have been developed. Such hybrid vehicles have been commonly applied to four-wheeled motor vehicles and are now expected to be applied to two-wheeled motor vehicles.
A motorcycle in which an engine is disposed between a front wheel and a rear wheel and an exhaust pipe for guiding exhaust gas emitted from the engine is extended forward relative to the engine, including an electric motor that is disposed behind a cylinder portion of the engine and is configured to apply a torque to a power transmission system including a crankshaft of the engine. The project relates to a hybrid motorcycle that is equipped with an engine mounted between a front wheel and a rear wheel and an electric motor configured to propel the motorcycle, and includes an exhaust pipe that is coupled to the engine and is extended forward relative to the engine. When an electric motor is incorporated into a motorcycle, it is desirable to dispose the electric motor in a location where the electric motor is less susceptible to disturbances in the environment for the purpose of stable operation, because the electric motor operates on electric power. Furthermore, it is necessary to mount the electric motor efficiently in a limited space of the motorcycle so as not to increase the size of a vehicle body of the motorcycle.
SUMMARY
The project addresses the above described conditions, and an object of the present invention is to provide a hybrid motorcycle configured to be driven by an engine and an electric motor suitably disposed therein. In such a construction, the exhaust pipe, elevated in temperature because of high-temperature exhaust gas emitted from the engine and flowing therein, is extended forward relative to the engine, whereas the electric motor is disposed behind the cylinder portion of the engine on the opposite side of the exhaust pipe. Therefore, the electric motor is less susceptible to heat radiation from the exhaust pipe. As a result, the electric motor can operate stably.
The engine may include a cylinder block forming the cylinder portion and a crankcase disposed at a lower portion of the cylinder block. The exhaust pipe may be extended rearward from a region forward of the cylinder block through a region below the crankcase. The electric motor may be disposed in a space formed behind the cylinder block and above the crankcase. In such a construction, since the electric motor is disposed in the space behind the cylinder block and above the crankcase, the size of the vehicle body is not substantially increased. In addition, since the exhaust pipe elevated in temperature is extended through the region below the crankcase whereas the electric motor is disposed above the crankcase, the electric motor is less susceptible to heat radiation from the exhaust pipe. As a result, the electric motor can operate more stably.
The electric motor and the crankshaft may be coupled to each other laterally of the crankcase via a chain and sprocket mechanism. A frame member may be extended rearward from a head pipe for supporting the front wheel, a swing arm extending substantially forward and rearward may be pivoted at a front portion thereof to the frame member, and the rear wheel is rotatably mounted to a rear portion of the swing arm. The electric motor may be disposed forward relative to the connecting point where the swing arm and the frame member are coupled to each other. In such a construction, since the electric motor is disposed between the connecting point where the front portion of the swing arm is coupled to the frame member and the cylinder portion of the engine so that the heavy weight of the electric motor is positioned near the center of gravity of the motorcycle. Therefore, weight of the motorcycle is well-balanced.
The motorcycle may further comprise a starter motor configured to apply a torque to the crankshaft to start the engine, a first electric power supplying unit configured to supply an electric power to the starter motor, and a second electric power supplying unit configured to supply the electric power to the electric motor and to have a voltage higher than a voltage of the first electric power supplying unit. The first electric power supplying unit may be configured to be able to be charged with the electric power supplied from the second electric power supplying unit. In such a construction, since the first electric power supplying unit configured to supply the electric power to the starter motor is charged with the electric power supplied from the second electric power supplying unit configured to supply the electric power to the electric motor, there is no need for an electric generator for charging the first electric power supplying unit. As a result, the size of the vehicle body is not substantially increased.
DETAILED DESCRIPTION
As shown in FIG. 1, the motorcycle 1 includes a front wheel 2 and a rear wheel 3. The front wheel 2 is rotatably mounted to a lower end portion of a front fork 4 extending substantially vertically. The front fork 4 is mounted on a steering shaft (not shown) by an upper bracket (not shown) attached to an upper end portion thereof, and an under bracket located below the upper bracket. The steering shaft is rotatably supported by a head pipe 5 externally attached to the steering shaft. A bar-type steering handle 6 extending rightward and leftward is attached to the upper bracket. When the rider rotates the steering handle 6 clockwise or counterclockwise, the front wheel 2 is turned to a desired direction with the steering shaft. A fuel tank 7 is disposed behind the steering handle 4. A straddle-type seat 8 is disposed behind the fuel tank 7.
A pair of right and left main frame members 9 (only left main frame member 9 is illustrated in FIG 1 ) forming a frame of a vehicle body extend to be tilted slightly downward and rearward from the head pipe 5. A pair of right and left pivot frame members (left pivot frame member is illustrated in FIG. 1) 10 are coupled to rear portions of the main frame members 9. A swing arm 11 extending substantially forward and rearward is pivotally mounted at a front end portion thereof to each pivot frame member 10. The rear wheel 3 which is a drive wheel is rotatably mounted to a rear end portion of the swing arm 11. An engine E is mounted on the right and left main frame members 9 and the pivot frame members 10 in such a manner that the engine E is disposed below the main frame members 9 and forward of the pivot frame members 10. A cowling 17 extends from a front portion to side portions of the vehicle body to cover the engine E and other components.