Abstract: A power unit has an internal combustion engine and a first auxiliary machine. The internal combustion engine includes a crankshaft and a balancer shaft. The first auxiliary machine operates on rotational power generated in the internal combustion engine. The first auxiliary machine is driven by rotational power of the balancer shaft.

Abstract: An oil passageway structure for IC engines includes a generator provided on one end side of a crankshaft, a generator cover that covers the generator and is fixed to an engine crankcase, a protective cover provided outside the generator cover and a water pump attached to an outer surface of the protective cover and having a drive shaft coaxially connected to one end of the crankshaft. The generator cover includes oil passageways that supply engine oil from the crankcase to the generator, and a generator cover-side guide portion that flows out engine oil collected from a generator housing space housing the generator toward the protective cover, and the protective cover includes a protective cover-side guide portion that guides and supplies the engine oil flowing out from the generator cover-side guide portion to the drive shaft of the water pump.

Abstract: A vehicle includes a front wheel, a rear wheel, and a power unit. The power unit is disposed between the front wheel and the rear wheel in a front-rear direction of the vehicle. An internal combustion engine and a compressor are modularized. The compressor is configured to operate on rotational power generated in the internal combustion engine. The internal combustion engine includes a crankshaft and an output shaft. Rotation axes of the crankshaft and the output shaft are parallel to each other and extend in the front-rear direction of the vehicle. The compressor is disposed on one side of the crankshaft in a left-right direction. The output shaft is disposed on the other side of the crankshaft in the left-right direction.

Abstract: A vehicle includes a front wheel, a rear wheel, a power unit in which an internal combustion engine and a compressor are modularized, and a seat. The compressor is configured to operate on rotational power generated in the internal combustion engine. The power unit is disposed between the front wheel and the rear wheel in a front-rear direction of the vehicle, and is disposed to place the compressor below the seat.

Abstract: An oil passageway structure for IC engines includes a generator provided on one end side of a crankshaft, a generator cover that covers the generator and is fixed to an engine crankcase, a protective cover provided outside the generator cover and a water pump attached to an outer surface of the protective cover and having a drive shaft coaxially connected to one end of the crankshaft. The generator cover includes oil passageways that supply engine oil from the crankcase to the generator, and a generator cover-side guide portion that flows out engine oil collected from a generator housing space housing the generator toward the protective cover, and the protective cover includes a protective cover-side guide portion that guides and supplies the engine oil flowing out from the generator cover-side guide portion to the drive shaft of the water pump.

Abstract: A cylinder head of an internal combustion engine includes a first exhaust port section having an upstream inlet opened and closed by a first exhaust valve, a second exhaust port section having an upstream inlet opened and closed by a second exhaust valve, and a collective exhaust port section into which the first and second exhaust port sections merge at downstream ends thereof. In a fixing structure for an exhaust gas sensor, the sensor is fixed to the collective exhaust port section with its sensing tip in the port section. An exhaust gas guide part is formed, at a position upstream of the sensor, on an internal wall of the port section, opposite the internal wall to which the sensor is fixed, so as to bulge out to guide exhaust gas toward the sensor, whereby exhaust gas is effectively intermixed and directed to the sensor with resultant increased sensing accuracy.

Abstract: An intake port is configured such that a center position of an intake upstream side opening is offset to one side in a juxtaposition direction of intake downstream side openings with respect to a center position between the intake downstream side openings in the juxtaposition direction as viewed in plan of a cylinder head. An injector is configured such that a fuel injection center axial line is inclined to the other side in the juxtaposition direction with respect to a center axial line of the intake upstream side opening as viewed in plan of the cylinder head.

Abstract: A cylinder head of an internal combustion engine includes a first exhaust port section having an upstream inlet opened and closed by a first exhaust valve, a second exhaust port section having an upstream inlet opened and closed by a second exhaust valve, and a collective exhaust port section into which the first and second exhaust port sections merge at downstream ends thereof. In a fixing structure for an exhaust gas sensor, the sensor is fixed to the collective exhaust port section with its sensing tip in the port section. An exhaust gas guide part is formed, at a position upstream of the sensor, on an internal wall of the port section, opposite the internal wall to which the sensor is fixed, so as to bulge out to guide exhaust gas toward the sensor, whereby exhaust gas is effectively intermixed and directed to the sensor with resultant increased sensing accuracy.

Abstract: An internal combustion engine can include a first ignition plug disposed on the inner side of a range surrounded by a plurality of intake valves and a plurality of exhaust valves with a cylinder head viewed in parallel to a cylinder axial line and standing uprightly along the cylinder axial line. A second ignition plug is inclined with respect to the cylinder axial line on the outer side of the range. The second ignition plug is disposed on the opposite side to a valve driving mechanism with respect to the cylinder axial line on the outer side of the range.

Abstract: An intake port is configured such that a center position of an intake upstream side opening is offset to one side in a juxtaposition direction of intake downstream side openings with respect to a center position between the intake downstream side openings in the juxtaposition direction as viewed in plan of a cylinder head. An injector is configured such that a fuel injection center axial line is inclined to the other side in the juxtaposition direction with respect to a center axial line of the intake upstream side opening as viewed in plan of the cylinder head.

Abstract: An internal combustion engine can include a first ignition plug disposed on the inner side of a range surrounded by a plurality of intake valves and a plurality of exhaust valves with a cylinder head viewed in parallel to a cylinder axial line and standing uprightly along the cylinder axial line. A second ignition plug is inclined with respect to the cylinder axial line on the outer side of the range. The second ignition plug is disposed on the opposite side to a valve driving mechanism with respect to the cylinder axial line on the outer side of the range.

Abstract: An internal combustion engine including a transmission for transmitting power from a crankshaft to an output shaft through speed change, with the speed change in the transmission being performed by the driving of a speed change electric motor through a speed change drive mechanism, wherein power transmission control means for controlling the transmission of power from the crankshaft to the transmission is provided at one end of the crankshaft, and at least a part of the speed change electric motor and the speed change drive mechanism is disposed on the outside of the power transmission control means. This configuration of the internal combustion engine is reduced in size because of the layout of the speed change drive mechanism and the speed change electric motor.

Abstract: To provide a clutch release mechanism which can restrain vibrations of a ball while allowing the ball to be loosely fitted when it is not in operation to ensure the engaged state of a clutch. A clutch release mechanism is configured in such a manner that a gap is defined between a clutch cam plate or a receiving plate and a ball unit so that the ball unit can slide between the clutch cam plate and the receiving plate. An urging spring is provided for urging the ball unit in the direction of being slid toward the clutch cam plate. A C-ring for restricting the ball unit from coming out from a boss member is attached to the peripheral portion of the boss member.

Abstract: An internal combustion engine including a transmission for transmitting power from a crankshaft to an output shaft through speed change, with the speed change in the transmission being performed by the driving of a speed change electric motor through a speed change drive mechanism, wherein power transmission control means for controlling the transmission of power from the crankshaft to the transmission is provided at one end of the crankshaft, and at least a part of the speed change electric motor and the speed change drive mechanism is disposed on the outside of the power transmission control means. This configuration of the internal combustion engine is reduced in size because of the layout of the speed change drive mechanism and the speed change electric motor.

Abstract: To provide a clutch release mechanism which can restrain vibrations of a ball while allowing the ball to be loosely fitted when it is not in operation to ensure the engaged state of a clutch. A clutch release mechanism is configured in such a manner that a gap is defined between a clutch cam plate or a receiving plate and a ball unit so that the ball unit can slide between the clutch cam plate and the receiving plate. An urging spring is provided for urging the ball unit in the direction of being slid toward the clutch cam plate. A C-ring for restricting the ball unit from coming out from a boss member is attached to the peripheral portion of the boss member.

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 oil jet device for piston cooling in which no press-fitting device is required, and the O-ring is prevented from being broken. A filter plug is inserted into an oil passage opening from the crank journal of a crankcase toward the side of the lower portion of the cylinder, and the crank journal is sealed by a plain bearing being abutted against the filter plug. The oil passage is formed by ring-shaped feed paths formed in the ring-shape on the bearing portions on the plain bearing and the crankcase.

Abstract: To provide a system for lubricating an engine for a personal watercraft, which is capable of simplifying an oil piping structure. An oil pump driven by a crankshaft of an engine and a relief valve for controlling a discharge pressure of the oil pump are provided in an oil tank provided on an extension of the crankshaft of the engine. Suction/discharge passages and the like for the oil pump are provided integrally with a tank main body. An oil filter in communication with the oil pump is provided in an upper portion of the oil tank, and communication passages for the oil filter are provided integrally with the oil tank. The oil filter is aligned with an opening of a deck. The tank main body covers drive chambers for accessories such as an ACG, a balancer shaft, and a starter motor of the engine.

Abstract: An oil jet device for piston cooling in which no press-fitting device is required, and the O-ring is prevented from being broken. A filter plug is inserted into an oil passage opening from the crank journal of a crankcase toward the side of the lower portion of the cylinder, and the crank journal is sealed by a plain bearing being abutted against the filter plug. The oil passage is formed by ring-shaped feed paths formed in the ring-shape on the bearing portions on the plain bearing and the crankcase.

Abstract: To provide a system for lubricating an engine for a personal watercraft, which is capable of simplifying an oil piping structure. An oil pump driven by a crankshaft of an engine and a relief valve for controlling a discharge pressure of the oil pump are provided in an oil tank provided on an extension of the crankshaft of the engine. Suction/discharge passages and the like for the oil pump are provided integrally with a tank main body. An oil filter in communication with the oil pump is provided in an upper portion of the oil tank, and communication passages for the oil filter are provided integrally with the oil tank. The oil filter is aligned with an opening of a deck. The tank main body covers drive chambers for accessories such as an ACG, a balancer shaft, and a starter motor of the engine.