Abstract: A multiple disc clutch includes a pressing member movable in an axial direction and which turns together with an output shaft to compress driving friction plates and driven friction plates, a clutch spring that axially presses the pressing member, a clutch lifter arranged coaxially with the pressing member and a lifter plate that is held by the periphery of the clutch lifter via a clutch bearing. The lifter plate moves the pressing member in a reverse direction to a direction pressed by the clutch spring according to the axial movement of the clutch lifter. This multiple disc clutch does not require a dedicated clutch lifter for every clutch bearing different in size and therefore the cost is reduced.

Abstract: A multiple disc clutch includes a pressing member that can be axially moved and that is turned together with an output shaft so as to compress driving friction plates and driven friction plates, a ringed set plate is provided on a side of the pressing member so as to receive a load by a clutch spring that axially presses the pressing member and a cam plate fixed to the pressing member so as to enable increasing or reducing frictional fitting force of the driving friction plates and the driven friction plates. The area for receiving the set plate is extended using a minimum number of parts, preventing a shape of the pressing member from being intricate and strength for supporting the set plate is enhanced. A part of the set plate axially touches the cam plate.

Abstract: A multi-plate clutch includes a clutch inner member, having a cylindrical portion and a pressure-applying plate portion, and a pressure-receiving plate opposite the pressure-applying plate portion with plural driving and driven friction plates interposed therebetween. The multi-plate clutch also includes a center cam having a disc portion, an assist cam and a slipper cam disposed on the disc portion. The assist and slipper cams include identical material, and have substantially identical shapes. An outer circumference of the assist cam is splined to an inner circumference of the cylindrical portion of the clutch inner member, so the assist cam can move in the axial direction relative to the clutch inner member. An outer circumference of the slipper cam is splined to the inner circumference of the cylindrical portion, so that axial motion of the slipper cam, relative to the clutch inner member away from the disc portion, is limited.

Abstract: A multi-plate clutch includes clutch discs which are disposed between a clutch outer and a clutch inner and are movable in an axial direction of the transmission shaft to permit and cut off the transmission of the rotational driving force from a crankshaft to a transmission shaft. A first biasing mechanism is configured to apply a clamping force to the clutch discs. A cam mechanism is configured to adjust the clamping force in accordance with the rotational driving force. A second biasing mechanism is configured to generate a biasing force to separate the clutch discs away from one another and to weaken the clamping force. The cam mechanism is configured to apply to the second biasing mechanism a force against the biasing force generated by the second biasing mechanism in accordance with the rotational driving force.

Abstract: A multiple disk clutch includes a clutch outer, a clutch inner, frictional disks, a cam mechanism, and a vibration isolating member. The clutch inner is provided inside the clutch outer and configured to transmit a rotational driving force from the clutch outer to a transmission shaft. The frictional disks are movable in an axial direction of the transmission shaft to thereby make and break transmission of the rotational driving force from the clutch outer to the clutch inner. The cam mechanism is provided inside the clutch outer and configured to apply a pressing force to the frictional disks according to the rotational driving force from the crankshaft. The cam mechanism is configured to relax the pressing force applied to the frictional disks when a load from the transmission shaft exceeds a predetermined value. The vibration isolating member is provided at the clutch inner.

Abstract: A disposition structure of a heat exchanger (oil cooler) in a motorcycle mounted in the central part in front of the upper part of the crankcase of an internal combustion engine E mounted on the motorcycle. When viewed from the front of the motorcycle, the oil cooler is located between the front forks. The oil cooler is disposed so that the fin surface of the cooling fins of the heat exchanger are perpendicular or substantially perpendicular to an air flow that goes between the front forks and above the front wheel. In the disposition structure so configured, cooling efficiency of the heat exchanger is improved.

Abstract: A cylinder head cooling structure and an oil temperature control system are provided for an internal combustion engine having a plurality of cylinders, each having a plurality of intake ports and a plurality of exhaust ports. The engine includes cooling oil jackets surrounding the spark plugs in the cylinder head, a thermostat attached to the front surface of the crankcase independently of an oil filter, and an oil temperature sensor disposed on a rear face of the cylinder block above the crankcase in an oil supply path formed on the cylinder rear face for supplying oil to the oil jackets. Oil passages conducting oil into the oil jacket are provided between two separate parts of a bifucated intake port and between two separate parts of a bifurcated exhaust port, and only cooling system oil reaching high temperatures is allowed to flow through the thermostat, thereby improving temperature control response.

Abstract: A multiplate clutch includes at least one driving friction plate configured to be rotated by a driving portion, at least one driven friction plate provided to face the at least one driving friction plate and configured to rotate the driven portion, a pressure applying unit configured to apply a pressing force to the at least one driving friction plate and the at least one driven friction plate to transmit the driving force from the driving portion to the driven portion via the at least one driving friction plate and the at least one driven friction plate, a first cam unit including first concave-convex cams and configured to increase the pressing force in accordance with an increase of the driving force, and a second cam unit configured to function as a back torque limiter mechanism and including second concave-convex cams which are different from the first concave-convex cams.

Abstract: An air-cooled internal combustion engine includes a cylinder block having a plurality of cylinder bores disposed in parallel to each other, a cylinder head secured to an upper portion of the cylinder block, a crankshaft, two camshafts disposed in a parallel, juxtaposed relationship to each other so as to extend perpendicularly to a forward and backward direction of a vehicle on which the engine is mounted at an upper portion of said cylinder head and positioned on front and rear sides of the engine relative to each other, and a camshaft driving mechanism for transmitting rotational driving force of the crankshaft to the camshafts. A cooling space into which wind can be introduced is formed below that one of the camshafts which is positioned on the front side of the engine. The entire cylinder head is thus cooled efficiently, including portions corresponding to the cylinders disposed at intermediate positions of the engine.

Abstract: An inventive cooling unit for an internal combustion engine comprises a plurality of cooling fins provided on outer surfaces of a cylinder block and a cylinder head, and vibration control rubbers interposed between cooling fins that face each other so as form a cooling air guide which guides air flow along lateral sides of the engine to rear parts of the engine. The cooling unit significantly increases the cooling efficiency of a cylinder and prevents vibration of cooling fins by interposing vibration control rubbers between cooling fins that face each other. The vibration control rubbers are formed in a streamlined shape and direct the flow of traveling air within the cooling fins about the exterior surface of the engine. The arrangement of the vibration control rubbers on side surfaces of the engine is such that angle ? of longitudinal axes of the vibration control rubbers with respect to the advancing direction of the vehicle becomes gradually larger moving from the front to the rear of the engine.

Abstract: A dry multiple-disk clutch for transmitting power from the crankshaft of a motorcycle to a transmission input shaft and cutting off power transmission includes an outer clutch member interlocked with the crankshaft so as to be driven for rotation, a plurality of driving friction disks interlocked with the outer clutch member, a plurality of driven friction disks alternated with the driving friction disks and interlocked with the transmission input shaft, and a pressure member disposed opposite to the outer clutch member with the driving and the driven friction disks arranged alternately between the outer clutch member and the pressure member, and capable of moving in opposite axial direction to compress the driving and the driven friction disks together and to disengage the driven friction disks from the driving friction disks.

Abstract: A cylinder head cooling structure and an oil temperature control system are provided for an internal combustion engine having a plurality of cylinders, each having a plurality of intake ports and a plurality of exhaust ports. The engine includes cooling oil jackets surrounding the spark plugs in the cylinder head, a thermostat attached to the front surface of the crankcase independently of an oil filter, and an oil temperature sensor disposed on a rear face of the cylinder block above the crankcase in an oil supply path formed on the cylinder rear face for supplying oil to the oil jackets. Oil passages conducting oil into the oil jacket are provided between two separate parts of a bifucated intake port and between two separate parts of a bifurcated exhaust port, and only cooling system oil reaching high temperatures is allowed to flow through the thermostat, thereby improving temperature control response.

Abstract: An intercooler has a case through which supercharging air passes, and a heat exchanger 4 mounted inside the case which allows heat exchange between the supercharging air and a cooling fluid. A frame body 15 is provided at the circumferential edges of air passage portions of the heat exchanger 4 on a supercharging air intake side and a supercharging air outlet side to reduce the gap between the heat exchanger and the inner wall of the case. The heat exchanger 4 has a pair of tanks 43 and 44, tubes communicating between the tanks, and a plurality of fins 46 set along the tubes, and assumes a structure that allows the supercharging air to pass through the heat exchanger a plurality of times by sequentially passing through blocks formed by dividing a heat exchanging unit 4A into a plurality of blocks with partitioning plates 15d.

Abstract: A disposition structure of a heat exchanger (oil cooler) in a motorcycle mounted in the central part in front of the upper part of the crankcase of an internal combustion engine E mounted on the motorcycle. When viewed from the front of the motorcycle, the oil cooler is located between the front forks. The oil cooler is disposed so that the fin surface of the cooling fins of the heat exchanger are perpendicular or substantially perpendicular to an air flow that goes between the front forks and above the front wheel. In the disposition structure so configured, cooling efficiency of the heat exchanger is improved.

Abstract: A heat exchanger is interposed between a supercharger of an internal combustion engine and an intake port of the internal combustion engine. The plate partially closes a space between an outer periphery of heat exchanger fins housed in a case and a case inner wall surface to form an air channel in a portion other than a closing part thereof. The plate may be constructed as an aluminum plate. The outlet is provided with a net member for foreign matter passage prevention.

Abstract: An air-cooled internal combustion engine includes a cylinder block having a plurality of cylinder bores disposed in parallel to each other, a cylinder head secured to an upper portion of the cylinder block, a crankshaft, two camshafts disposed in a parallel, juxtaposed relationship to each other so as to extend perpendicularly to a forward and backward direction of a vehicle on which the engine is mounted at an upper portion of said cylinder head and positioned on front and rear sides of the engine relative to each other, and a camshaft driving mechanism for transmitting rotational driving force of the crankshaft to the camshafts. A cooling space into which wind can be introduced is formed below that one of the camshafts which is positioned on the front side of the engine. The entire cylinder head is thus cooled efficiently, including portions corresponding to the cylinders disposed at intermediate positions of the engine.

Abstract: An inventive cooling unit for an internal combustion engine comprises a plurality of cooling fins provided on outer surfaces of a cylinder block and a cylinder head, and vibration control rubbers interposed between cooling fins that face each other so as form a cooling air guide which guides air flow along lateral sides of the engine to rear parts of the engine. The cooling unit significantly increases the cooling efficiency of a cylinder and prevents vibration of cooling fins by interposing vibration control rubbers between cooling fins that face each other. The vibration control rubbers are formed in a streamlined shape and direct the flow of traveling air within the cooling fins about the exterior surface of the engine. The arrangement of the vibration control rubbers on side surfaces of the engine is such that angle ? of longitudinal axes of the vibration control rubbers with respect to the advancing direction of the vehicle becomes gradually larger moving from the front to the rear of the engine.

Abstract: To enhance the responsiveness of a relief valve, to lower the height of an engine, and to remove foreign matter entrapped in oil. A cylindrical relief valve for a dry sump type engine is disposed in parallel to a main gallery which is disposed in parallel to a crank shaft. Alternatively, the relief valve is disposed in an oil tank. Furthermore, a strainer for straining oil recovered in the oil tank is provided in the oil tank.

Abstract: An ignition device for a personal watercraft engine, which allows mounting of a four-cycle engine on the personal watercraft and prevents occurrence of leakage of current. The engine for driving a jet propelling pump is provided in a watercraft body surrounded by a hull and a deck. A spark plug for spark ignition is provided in a cylinder head of the engine, and an integral cap ignition coil having a water-proof structure is water-tightly provided in the cylinder head in such a manner as to be located on the spark plug at an uppermost portion of the engine. A water-escape groove continuous to a recess for receiving a cap is formed in an upper surface of the cylinder head. A bottom surface of the escape groove is formed into a shape tilted downwardly.

Abstract: A dry multiple-disk clutch for transmitting power from the crankshaft of a motorcycle to a transmission input shaft and cutting off power transmission includes an outer clutch member interlocked with the crankshaft so as to be driven for rotation, a plurality of driving friction disks interlocked with the outer clutch member, a plurality of driven friction disks alternated with the driving friction disks and interlocked with the transmission input shaft, and a pressure member disposed opposite to the outer clutch member with the driving and the driven friction disks arranged alternately between the outer clutch member and the pressure member, and capable of moving in opposite axial direction to compress the driving and the driven friction disks together and to disengage the driven friction disks from the driving friction disks.