Abstract: A torque shock or vibrations caused by the rotary inertia of a hydrostatic continuously variable transmission is reduced to improve ride quality of a vehicle when excessive torque occurs in a torque transmission path between a crankshaft and a drive wheel. A motorcycle includes a hydrostatic continuously variable transmission rotatably driven by torque of a crankshaft of an internal combustion engine. A rear wheel is rotatably driven by torque from the transmission. A torque damper absorbs excessive torque occurring in a torque transmission path from the crankshaft to the rear wheel. The torque dampers include an input side torque damper disposed in an input side torque transmission path between the crank shaft and the transmission and an output side torque damper disposed in an output side torque transmission path between the transmission and the rear wheel.

Abstract: Detecting a hydraulic pressure condition at a supplied part while reducing the cost of an oil passage forming member provided with an oil passage for conducting oil to the supplied part. In a right cover which is provided with a bent oil passage for conducting oil to a hydraulic type running clutch and which is fitted with the hydraulic pressure sensor, the oil passage is composed of a first hole and a second hole intersecting the first hole so as to constitute a bent passage part. The second hole, which is one of the first hole and the second hole, has an aperture end part with the aperture end part being closed with the hydraulic pressure sensor. The bent passage part is a bent passage part, located at a position nearest to a hydraulic pressure chamber of the running clutch, of the oil passage.

Abstract: To enhance the noise reducing effect of a sound insulation structure which includes a cover member for covering a power unit from the outside so as to reduce the radiant sound generated from the power unit, and a resonator. A sound insulation structure includes an armor cover for covering a left case half and a left cover constituting a side part cover of the power unit from the left side so as to reduce the radiant sound generated from the side part cover and enhance an appearance quality of the power unit, and the resonator capable of resonating at a specified frequency of the radiant sound. The resonator is disposed in a space formed between the side part cover and the armor cover in the state of being out of contact with the armor cover, and is attached to the side part cover in contact with the latter.

Abstract: A torque damper for a power unit includes a rotating shaft on which the torque damper is mounted to reduce the axial size and weight. A torque damper for absorbing excessive torque occurring in a torque transmission path between an output shaft of a running clutch and an intermediate shaft includes an input cam member adapted to receive torque of the output shaft and an output cam member. A driven gear adapted to apply torque of the output shaft to the input cam member is provided on the input cam member rotatably supported by the intermediate shaft. In the torque damper, a torque-absorbing portion for absorbing excessive torque includes an input cam portion of the input cam member and an output cam portion of the output cam member and is disposed between a pair of bearings. One bearing is disposed between the input cam portion and the driven gear.

Abstract: The degradation of a feeling of ride is prevented by preventing engagement/disengagement (sudden engagement/disengagement) of a motorcycle hydraulic clutch due to a lack of hydraulic pressure. Before a hydraulic sensor issues a hydraulic pressure-lowering detection signal Sx, an oil level sensor issues an oil level-lowering warning signal Sf in a state wherein a sufficient oil quantity is such so as not to bring an neutral drive switching clutch into a disengagement state is present even if hydraulic pressure lowers resulting from an inclined oil level due to sudden deceleration, sudden start, drive in a slope, or the like. Thus, the neutral drive switching clutch can be prevented from disengaging or engaging (suddenly disengaging or engaging).

Abstract: An oil pump assembly includes a plurality of pump chambers constituting a plurality of oil pumps, respectively, a plurality of rotors are fitted into the pump chambers, respectively, with a single driving shaft carrying the plurality of rotors to form a single body. Oil pumped up from an oil pan is supplied under pressure to different associated destinations with the relief valves being arranged compactly to reduce the size of the oil pump assembly. Oil pumps are provided with respective relief valves provided to pass oil discharged from the corresponding pump chambers therethrough and the axes of the relief valves are arranged parallel to the driving shaft. A driving shaft is provided on which a plurality of the inner rotors are carried concentrically and integrally. The rotors are connected to the driving shaft and changed depending on discharge oil pressures, thereby preventing the driving shaft from increasing its diameter.

Abstract: A mode changeover control system for a transmission wherein the starting of a vehicle can be prevented even if the transmission is changed over to the drive mode side while a side stand is in an erected position. In a motorcycle including a mode changeover mechanism for a continuously variable transmission, and a side stand, there is provided a changeover operation section changed over by the driver between operation positions corresponding respectively to a drive mode position and a neutral mode position of the mode changeover mechanism. An electronic control unit operates the mode changeover mechanism based on the changeover operation position of the changeover operation section. The control section is configured so as to continually maintain the mode changeover mechanism in the neutral mode position even if the changeover operation section is operated to a drive mode operation position while the side stand is in a stored position.

Abstract: The degradation of a feeling of ride is prevented by preventing engagement/disengagement (sudden engagement/disengagement) of a motorcycle hydraulic clutch due to a lack of hydraulic pressure. Before a hydraulic sensor issues a hydraulic pressure-lowering detection signal Sx, an oil level sensor issues an oil level-lowering warning signal Sf in a state wherein a sufficient oil quantity is such so as not to bring an neutral drive switching clutch into a disengagement state is present even if hydraulic pressure lowers resulting from an inclined oil level due to sudden deceleration, sudden start, drive in a slope, or the like. Thus, the neutral drive switching clutch can be prevented from disengaging or engaging (suddenly disengaging or engaging).

Abstract: A torque damper for a power unit includes a rotating shaft on which the torque damper is mounted to reduce the axial size and weight. A torque damper for absorbing excessive torque occurring in a torque transmission path between an output shaft of a running clutch and an intermediate shaft includes an input cam member adapted to receive torque of the output shaft and an output cam member. A driven gear adapted to apply torque of the output shaft to the input cam member is provided on the input cam member rotatably supported by the intermediate shaft. In the torque damper, a torque-absorbing portion for absorbing excessive torque includes an input cam portion of the input cam member and an output cam portion of the output cam member and is disposed between a pair of bearings. One bearing is disposed between the input cam portion and the driven gear.

Abstract: To enhance the noise reducing effect of a sound insulation structure which includes a cover member for covering a power unit from the outside so as to reduce the radiant sound generated from the power unit, and a resonator. A sound insulation structure includes an armor cover for covering a left case half and a left cover constituting a side part cover of the power unit from the left side so as to reduce the radiant sound generated from the side part cover and enhance an appearance quality of the power unit, and the resonator capable of resonating at a specified frequency of the radiant sound. The resonator is disposed in a space formed between the side part cover and the armor cover in the state of being out of contact with the armor cover, and is attached to the side part cover in contact with the latter.

Abstract: A torque shock or vibrations caused by the rotary inertia of a hydrostatic continuously variable transmission is reduced to improve ride quality of a vehicle when excessive torque occurs in a torque transmission path between a crankshaft and a drive wheel. A motorcycle includes a hydrostatic continuously variable transmission rotatably driven by torque of a crankshaft of an internal combustion engine. A rear wheel is rotatably driven by torque from the transmission. A torque damper absorbs excessive torque occurring in a torque transmission path from the crankshaft to the rear wheel. The torque dampers include an input side torque damper disposed in an input side torque transmission path between the crank shaft and the transmission and an output side torque damper disposed in an output side torque transmission path between the transmission and the rear wheel.

Abstract: Detecting a hydraulic pressure condition at a supplied part while reducing the cost of an oil passage forming member provided with an oil passage for conducting oil to the supplied part. In a right cover which is provided with a bent oil passage for conducting oil to a hydraulic type running clutch and which is fitted with the hydraulic pressure sensor, the oil passage is composed of a first hole and a second hole intersecting the first hole so as to constitute a bent passage part. The second hole, which is one of the first hole and the second hole, has an aperture end part with the aperture end part being closed with the hydraulic pressure sensor. The bent passage part is a bent passage part, located at a position nearest to a hydraulic pressure chamber of the running clutch, of the oil passage.

Abstract: A transmission structure of a power unit for a vehicle is provided with a hydrostatic continuously variable transmission for shifting and transmitting driving force from an internal combustion engine to a rear wheel. An oil pump supplies oil to a hydrostatic continuously variable transmission and a neutral/drive switching clutch which is arranged between the transmission and a rear wheel. A hydraulic piston adjacent to each set of driving friction plates and driven friction plates is moved by pressure in an oil pressure chamber and which connects and disconnects the driving force. An oil passage to the neutral/drive switching clutch is branched from an oil passage from the oil pump to the upstream side of the transmission. The resulting configuration prevents a lowering operating pressure of the neutral/drive switching clutch.

Abstract: A viscous damper for driving accessories by a crankshaft though a viscous coupler of the viscous damper. The rotational driving force of the crankshaft is transmitted to the viscous damper hub through the meshing of a large diameter gear and a driven gear, the viscous damper forming a unit with the driven gear. The rotational driving force is further transmitted to a viscous damper housing through the hub and the viscous coupler, i.e., the viscous coupler including a number of plates which are movable relative to each other in a space filled with silicon oil. The rotational driving force, which is transmitted to the housing and is dampened in torque changes by the function of the coupler, is transmitted to a rotor shaft of an alternator to smoothly rotate the alternator rotor. A smooth performance in driving the accessories is ensured by the viscous damper having the viscous coupler.

Abstract: To provide a transmission shaft support mechanism, which includes a power unit case that contains a lubricating oil supply mechanism, and a gear shaft that supports a group of gears for power transmission. An intermediate shaft holder is contained in the power unit case for supporting an intermediate shaft having an idle gear so as to be attached to an intermediate shaft holder attachment surface formed on an inner wall of the power unit case such that the lubricating performance for the intermediate shaft is improved and the lubricating mechanism is simplified. Bolt holes are formed in the intermediate shaft holder and the intermediate shaft holder attachment surface. The oil supply passage for lubricating the intermediate shaft is formed along the bolt holes.

Abstract: An internal combustion engine and a transmission are supported by a saddle-ride type vehicle body having a front wheel in a front portion thereof. An oil cooler is installed without interference with other parts such as, for example, an exhaust pipe and the front wheel. Further, the distance between a water pump and the oil cooler is made shorter to shorten the length of a cooling water pipe. The power unit includes a crank shaft, an output shaft disposed in a rear portion of the power unit to output torque produced by the crank shaft to the exterior through a transmission, a water pump is adapted to be rotated with the torque transferred thereto from the crank shaft, and an oil cooler mounted on a rear surface of the power unit in a vehicle advancing direction below the output shaft and at a position lower than the crank shaft.

Abstract: A mode changeover control system for a transmission wherein the starting of a vehicle can be prevented even if the transmission is changed over to the drive mode side while a side stand is in an erected position. In a motorcycle including a mode changeover mechanism for a continuously variable transmission, and a side stand, there is provided a changeover operation section changed over by the driver between operation positions corresponding respectively to a drive mode position and a neutral mode position of the mode changeover mechanism. An electronic control unit operates the mode changeover mechanism based on the changeover operation position of the changeover operation section. The control section is configured so as to continually maintain the mode changeover mechanism in the neutral mode position even if the changeover operation section is operated to a drive mode operation position while the side stand is in a stored position.

Abstract: An oil pump assembly includes a plurality of pump chambers constituting a plurality of oil pumps, respectively, a plurality of rotors are fitted into the pump chambers, respectively, with a single driving shaft carrying the plurality of rotors to form a single body. Oil pumped up from an oil pan is supplied under pressure to different associated destinations with the relief valves being arranged compactly to reduce the size of the oil pump assembly. Oil pumps are provided with respective relief valves provided to pass oil discharged from the corresponding pump chambers therethrough and the axes of the relief valves are arranged parallel to the driving shaft. A driving shaft is provided on which a plurality of the inner rotors are carried concentrically and integrally. The rotors are connected to the driving shaft and changed depending on discharge oil pressures, thereby preventing the driving shaft from increasing its diameter.

Abstract: An internal combustion engine and a transmission are supported by a saddle-ride type vehicle body having a front wheel in a front portion thereof. An oil cooler is installed without interference with other parts such as, for example, an exhaust pipe and the front wheel. Further, the distance between a water pump and the oil cooler is made shorter to shorten the length of a cooling water pipe. The power unit includes a crank shaft, an output shaft disposed in a rear portion of the power unit to output torque produced by the crank shaft to the exterior through a transmission, a water pump is adapted to be rotated with the torque transferred thereto from the crank shaft, and an oil cooler mounted on a rear surface of the power unit in a vehicle advancing direction below the output shaft and at a position lower than the crank shaft.

Abstract: A viscous damper for driving accessories by a crankshaft though a viscous coupler of the viscous damper. The rotational driving force of the crankshaft is transmitted to the viscous damper hub through the meshing of a large diameter gear and a driven gear, the viscous damper forming a unit with the driven gear. The rotational driving force is further transmitted to a viscous damper housing through the hub and the viscous coupling means, i.e., the viscous coupling means comprising a number of plates which are movable relative to each other in a space filled with silicon oil. The rotational driving force, which is transmitted to the housing and is dampened in torque changes by the function of the coupling means, is transmitted to a rotor shaft of an alternator to smoothly rotate the alternator rotor. A smooth performance in driving the accessories is ensured by the viscous damper having the viscous coupling.