Abstract: A sensor mounting structure for an engine is provided. The sensor mounting structure offers a greater flexibility in mounting a sensor which detects an operation of an actuation member disposed at an inner wall spaced apart from an outer wall of a cylinder head of a valve gear. A sensor mounting structure for an engine includes a valve gear provided at a cylinder head and a sensor detecting an operation of the valve gear. The sensor is mounted on a sensor mounting hole formed at a head inner wall of the cylinder head covered with a cylinder head cover.

Abstract: An internal combustion engine for being mounted laterally on a saddle-type vehicle includes an AC generator disposed on an end portion of a crankshaft which is supported in a crankcase. An ACG cover covers the AC generator from outside widthwise across the vehicle. The ACG cover includes an electric power transmission line cover bulging portion covering electric power transmission lines extending to the ACG cover and bulging sideways outwardly widthwise across the vehicle. A crank angle sensor is disposed behind the electric power transmission line cover bulging portion in a vehicle front-back direction. The crank angle sensor is thus protected from flying stones, etc. without an increase in the number of parts used and an increase in the weight of the internal combustion engine.

Abstract: An internal combustion engine for being mounted laterally on a saddle-type vehicle includes an AC generator disposed on an end portion of a crankshaft which is supported in a crankcase. An ACG cover covers the AC generator from outside widthwise across the vehicle. The ACG cover includes an electric power transmission line cover bulging portion covering electric power transmission lines extending to the ACG cover and bulging sideways outwardly widthwise across the vehicle. A crank angle sensor is disposed behind the electric power transmission line cover bulging portion in a vehicle front-back direction. The crank angle sensor is thus protected from flying stones, etc. without an increase in the number of parts used and an increase in the weight of the internal combustion engine.

Abstract: An internal combustion engine is configured to satisfy the relation expressed by 0<Rv<0.000438×?2?0.0407×?+1.55 in a range of an intake valve overlap amount ?(°) from 20° to 45°, where Rv denotes an intake port volume ratio obtained by dividing an intake port internal volume Vp by a cylinder stroke volume Vc, and the intake valve overlap amount ?(°) is a crank angle from an intake valve opening timing when the intake valve starts opening to an intake top dead center of the piston. The engine improves output performance as well as both combustion performance and emission performance by suppressing reverse flow of the combustion gas into the intake system.

Abstract: Problem: The objective of the present invention is to provide a technique to enable more accurate measurement of oxygen contained in an exhaust gas in an exhaust device provided with an oxygen sensor. Solution: A catalyst which cleans the exhaust gas is provided in an exhaust pipe in an exhaust device that includes a muffler coupled downstream of the exhaust pipe, and an oxygen sensor is mounted on a pipe portion that is disposed downstream from the catalyst and that is directly coupled to the catalyst. The oxygen sensor is provided substantially perpendicular to the axial direction of the pipe portion through which the exhaust gas flows. The oxygen sensor includes a detecting portion, the detecting portion is disposed in a recessed portion formed in the muffler, and a wire is disposed on an outer side of the recessed portion.

Abstract: A sensor mounting structure for an engine is provided. The sensor mounting structure offers a greater flexibility in mounting a sensor which detects an operation of an actuation member disposed at an inner wall spaced apart from an outer wall of a cylinder head of a valve gear. A sensor mounting structure for an engine includes a valve gear provided at a cylinder head and a sensor detecting an operation of the valve gear. The sensor is mounted on a sensor mounting hole formed at a head inner wall of the cylinder head covered with a cylinder head cover.

Abstract: An internal combustion engine is configured to satisfy the relation expressed by 0<Rv<0.000438×?2?0.0407×0+1.55 in a range of an intake valve overlap amount ?(°) from 20° to 45°, where Rv denotes an intake port volume ratio obtained by dividing an intake port internal volume Vp by a cylinder stroke volume Vc, and the intake valve overlap amount ?(°) is a crank angle from an intake valve opening timing when the intake valve starts opening to an intake top dead center of the piston. The engine improves output performance as well as both combustion performance and emission performance by suppressing reverse flow of the combustion gas into the intake system.

Abstract: Problem: The objective of the present invention is to provide a technique to enable more accurate measurement of oxygen contained in an exhaust gas in an exhaust device provided with an oxygen sensor. Solution: A catalyst which cleans the exhaust gas is provided in an exhaust pipe in an exhaust device that includes a muffler coupled downstream of the exhaust pipe, and an oxygen sensor is mounted on a pipe portion that is disposed downstream from the catalyst and that is directly coupled to the catalyst. The oxygen sensor is provided substantially perpendicular to the axial direction of the pipe portion through which the exhaust gas flows. The oxygen sensor includes a detecting portion, the detecting portion is disposed in a recessed portion formed in the muffler, and a wire is disposed on an outer side of the recessed portion.

Abstract: To prevent a reduction in engine load detection accuracy due to variations in reluctor size within mass production tolerances, an engine control unit includes a pulse generator PC that detects a reluctor to output crank pulses. An angular velocity calculating unit calculates a first crank angular velocity on the basis of an interval between two crank pulses output in a predetermined section near compression top dead center TDC, and detects near overlap top dead center OLP the same reluctor used for calculating the first crank angular velocity to calculate a second crank angular velocity on the basis of an interval between generated two crank pulses. An engine load estimating unit calculates, as an engine load, a difference between the first crank angular velocity and the second crank angular velocity. The engine load is indicated mean effective pressure over a whole cycle including negative work done by the engine.

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 motorcycle includes an engine configured to expel an exhaust from combustion chambers of cylinders in a cylinder head through exhaust ports. Each of the cylinders is provided with a recessed portion provided in an exhaust passage wall surface in a central portion of an exhaust passage of a corresponding exhaust port. This makes it possible to maintain flow rate and flow velocity of the exhaust gas, and to decrease exhaust loss. As a result, it is possible to increase engine torque by use of a simple structure. In addition, no restriction is imposed on the layout of parts around the engine, because the recessed portions are provided in the exhaust ports.

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 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: To prevent a reduction in engine load detection accuracy due to variations in reluctor size within mass production tolerances, an engine control unit includes a pulse generator PC that detects a reluctor to output crank pulses. An angular velocity calculating unit calculates a first crank angular velocity on the basis of an interval between two crank pulses output in a predetermined section near compression top dead center TDC, and detects near overlap top dead center OLP the same reluctor used for calculating the first crank angular velocity to calculate a second crank angular velocity on the basis of an interval between generated two crank pulses. An engine load estimating unit calculates, as an engine load, a difference between the first crank angular velocity and the second crank angular velocity. The engine load is indicated mean effective pressure over a whole cycle including negative work done by the engine.

Abstract: A motorcycle includes an engine configured to expel an exhaust from combustion chambers of cylinders in a cylinder head through exhaust ports. Each of the cylinders is provided with a recessed portion provided in an exhaust passage wall surface in a central portion of an exhaust passage of a corresponding exhaust port. This makes it possible to maintain flow rate and flow velocity of the exhaust gas, and to decrease exhaust loss. As a result, it is possible to increase engine torque by use of a simple structure. In addition, no restriction is imposed on the layout of parts around the engine, because the recessed portions are provided in the exhaust ports.