Abstract: An ignition timing setting apparatus includes a pulse generator for generating crank pulses corresponding to crank angles, a crank angular speed variation calculating section for calculating a crank angular speed variation based on an interval of the crank pulses, an engine load estimating section for estimating an indicated mean effective pressure from the crank angular speed variation, and an ignition timing determining section having an ignition timing control map for determining an ignition timing advance quantity in accordance with the estimated indicated mean effective pressure and an engine temperature or an engine speed. Such ignition timing setting apparatus sets appropriate ignition timings for avoiding a knocking occurrence load range based on an accurate estimated engine load.

Abstract: A hybrid vehicle includes an engine; a motor; a power transmission mechanism and an oil pump for lubricating the engine and the power transmission mechanism with the rotation of a crankshaft. The oil pump has an oil pump shaft with an oil pump driven gear on one end thereof through a one-way clutch and an oil pump driven sprocket on the other end of the oil pump shaft through a one-way clutch. The oil pump driven gear is connected to a primary drive gear rotating integrally with a motor driven gear for transmitting the power of the motor to the drive wheel. The oil pump driven sprocket is connected to a cam chain of the engine to be rotated by power of the engine. The motor driven gear is disposed on one side of the crankshaft and the cam chain is disposed on the other side of the crankshaft.

Abstract: A hybrid vehicle in which an electric motor is disposed in the vicinity of a center of a vehicle body to reduce lateral expansion. The hybrid vehicle includes an engine, a motor, and a power transmission mechanism for transmitting power of the engine and the motor to a rear wheel. The engine is suspended on the vehicle body in a non-swingable manner with a cylinder extending in a substantially horizontal direction and a crankshaft provided to be oriented in a vehicle width direction. The electric motor is located in front of and above the crankshaft of the engine.

Abstract: An air-fuel ratio estimating device can include an amount of fuel injected calculating unit which can estimate the amount of fuel injected GF for each cycle on the basis of a driving time Tout of a fuel injection valve. A proportional constant calculating section determines a proportional constant K, using the estimated charging efficiency CE and the amount of fuel injected Gf, when the output value of a sensor is in a transition region R. When the sensor output value is not in the transition region R, an air-fuel ratio A/F is estimated from the determined proportional constant K, a charging efficiency CE calculated by a calculating section, and the amount of fuel injected Gf.

Abstract: A piston with transverse-rib through holes formed easily therein for reducing the cost of manufacturing. A piston includes a pair of mutually opposed longitudinal ribs individually formed with piston pin bosses interconnecting a pair of piston skirt portions on a back side of a piston head. A pair of transverse ribs interconnect the mutually opposed longitudinal ribs with the transverse ribs. The pair of transverse ribs are formed with transverse-rib through holes at places proximal to the back side of the piston head. A skirt opening is formed by cutting away a part of the piston skirt portion that is opposed to the transverse rib and faces the transverse-rib through hole.

Abstract: A technique for enabling reduction of fuel consumption without greatly changing an engine structure and without impairing a feeling of operation of a vehicle as a motorcycle. An engine includes a crankshaft and a primary gear integrated with the crankshaft that is attached such that the power of the engine is transmitted to a wheel. A one-way clutch transmits the power from the crankshaft to the primary gear but does not transmit the power from the primary gear to the crankshaft. The one-way clutch is provided between the crankshaft and the primary gear with a regenerative brake motor being provided on the primary gear. The engine is non-swingable mounted on the vehicle body with a cylinder extending in a substantially horizontal direction and a crankshaft provided to be oriented in a vehicle width direction. An electric motor is located in front of and above the crankshaft of the engine.

Abstract: An air-fuel ratio estimating device can include an amount of fuel injected calculating unit which can estimate the amount of fuel injected GF for each cycle on the basis of a driving time Tout of a fuel injection valve. A proportional constant calculating section determines a proportional constant K, using the estimated charging efficiency CE and the amount of fuel injected Gf, when the output value of a sensor is in a transition region R. When the sensor output value is not in the transition region R, an air-fuel ratio A/F is estimated from the determined proportional constant K, a charging efficiency CE calculated by a calculating section, and the amount of fuel injected Gf.

Abstract: An ignition timing setting apparatus includes a pulse generator for generating crank pulses corresponding to crank angles, a crank angular speed variation calculating section for calculating a crank angular speed variation based on an interval of the crank pulses, an engine load estimating section for estimating an indicated mean effective pressure from the crank angular speed variation, and an ignition timing determining section having an ignition timing control map for determining an ignition timing advance quantity in accordance with the estimated indicated mean effective pressure and an engine temperature or an engine speed. Such ignition timing setting apparatus sets appropriate ignition timings for avoiding a knocking occurrence load range based on an accurate estimated engine load.

Abstract: A hybrid vehicle includes an engine; a motor; a power transmission mechanism and an oil pump for lubricating the engine and the power transmission mechanism with the rotation of a crankshaft. The oil pump has an oil pump shaft with an oil pump driven gear on one end thereof through a one-way clutch and an oil pump driven sprocket on the other end of the oil pump shaft through a one-way clutch. The oil pump driven gear is connected to a primary drive gear rotating integrally with a motor driven gear for transmitting the power of the motor to the drive wheel. The oil pump driven sprocket is connected to a cam chain of the engine to be rotated by power of the engine. The motor driven gear is disposed on one side of the crankshaft and the cam chain is disposed on the other side of the crankshaft.

Abstract: A technique for enabling reduction of fuel consumption without greatly changing an engine structure and without impairing a feeling of operation of a vehicle as a motorcycle. An engine includes a crankshaft and a primary gear integrated with the crankshaft that is attached such that the power of the engine is transmitted to a wheel. A one-way clutch transmits the power from the crankshaft to the primary gear but does not transmit the power from the primary gear to the crankshaft. The one-way clutch is provided between the crankshaft and the primary gear with a regenerative brake motor being provided on the primary gear. The engine is non-swingable mounted on the vehicle body with a cylinder extending in a substantially horizontal direction and a crankshaft provided to be oriented in a vehicle width direction. An electric motor is located in front of and above the crankshaft of the engine.

Abstract: A hybrid vehicle in which an electric motor is disposed in the vicinity of a center of a vehicle body to reduce lateral expansion. The hybrid vehicle includes an engine, a motor, and a power transmission mechanism for transmitting power of the engine and the motor to a rear wheel. The engine is suspended on the vehicle body in a non-swingable manner with a cylinder extending in a substantially horizontal direction and a crankshaft provided to be oriented in a vehicle width direction. The electric motor is located in front of and above the crankshaft of the engine.

Abstract: A piston with transverse-rib through holes formed easily therein for reducing the cost of manufacturing. A piston includes a pair of mutually opposed longitudinal ribs individually formed with piston pin bosses interconnecting a pair of piston skirt portions on a back side of a piston head. A pair of transverse ribs interconnect the mutually opposed longitudinal ribs with the transverse ribs. The pair of transverse ribs are formed with transverse-rib through holes at places proximal to the back side of the piston head. A skirt opening is formed by cutting away a part of the piston skirt portion that is opposed to the transverse rib and faces the transverse-rib through hole.