Abstract: A multicylinder engine for a motorcycle includes a valve actuation mechanism having a hydraulically-operated valve pausing mechanism for holding at least one of an intake valve and an exhaust valve of selected cylinders in a suspended state. The valve actuation mechanism operates the intake valve and the exhaust valve, and controls flow of oil through an oil passage which introduces working oil to the valve pausing mechanism from a hydraulic-pressure control device. Air-bleeding holes are formed in the cylinder head. The air-bleeding holes are fluidly connected with portions of the oil passages that are located at a highest level in the oil passages while the motorcycle is parked in an inclined state with its side stand down.

Abstract: In a V-type engine for a vehicle, in which a hydraulic valve rest mechanism which selectively holds at least one of an intake valve and an exhaust valve corresponding to a part of plural cylinders in a valve-closed rest state in correspondence with a vehicle running status is provided in a valve actuation unit, and a hydraulic controller which controls hydraulic pressure of the valve rest mechanism is provided in a main engine body, to reduce the distance of oil passage from the hydraulic controller to the hydraulic valve rest mechanism and simplify the structure of the oil passage. A hydraulic controller is provided on at least one side surface of a cylinder head, and may be generally oriented along a line which is substantially parallel to a central axis of a cylinder bore.

Abstract: In a variable valve timing mechanism, a valve-lifting cam member is fitted, slidably in tile circumferential direction, onto a camshaft that is driven to rotate in synchronization with a crankshaft of a four-stroke cycle internal combustion engine. An eccentric collar is set between a driving collar fixed on the camshaft and the valve-lifting cam member. A driving projection is formed in the driving collar and engages with one of sandwiching portions of the eccentric collar. A driven protrusion is formed in the valve-lifting cam member and engages with another one of the sandwiching portions of the eccentric collar. A linkage mechanism includes the eccentric collar, the drive, and the driven protrusions. The variable valve timing mechanism adjusts the timing of opening and closing of the valve while the rotational phase of the valve-lifting cam member is cyclically varied relative to the camshaft by the eccentricity of the eccentric collar.

Abstract: A valve stopping mechanism wherein when hydraulic fluid pressure is low a cylinder operating state is set and a response of a switch from a cylinder stop state to the cylinder operating state is high. An intake valve and an exhaust valve, a first intake valve spring and a first exhaust valve spring are provided for energizing the valves in the direction of closing the valves, valve drive cams, valve stopping mechanisms, on the basis of a stop hydraulic fluid pressure and energization of plunger springs, for selectively generating valve operating and valve stop states. The valve stopping mechanism generates the operating state when the energizing force of the plunger spring is larger than the press force of the stop hydraulic fluid pressure and generates the stop state when the press force of the stop hydraulic fluid pressure is larger than the energizing force of the plunger spring.

Abstract: A simpler configuration of a mechanism for stopping intake/exhaust valves opened/closed by a valve opening/closing mechanism of a rocker arm. An engine E includes an exhaust valve for opening/closing an exhaust port of an exhaust path with a first exhaust valve spring for energizing the exhaust valve in a valve closing direction. An exhaust valve drive cam is rotated in correspondence with the rotation of an engine crankshaft. A rocker arm is swingably provided between the exhaust valve and the exhaust valve drive cam with one end that abuts on the exhaust valve drive cam being pressed according to rotation of the exhaust valve drive cam and swinging to press the exhaust valve by a press member at the other end to move to the open side. An exhaust valve stopping mechanism is provided between the press member of the rocker arm and the exhaust valve.

Abstract: A variable valve operating mechanism of a four-stroke internal combustion engine includes a slide pin energized by a pin spring in a direction while oil pressure acting on the slide pin in the opposite direction through oil pressure supply passages. The slide pin moves by controlling the oil pressure causing a stem contact surface and a stem through hole to selectively face a valve stem. The mechanism also includes an oil discharge passage including a discharge port which is opened to allow oil acting the slide pin to be discharged when the valve lifter is pressed by a valve operating cam to move for opening the valve. The mechanism is capable of quickly moving the slide pin upon the release of oil pressure when the valve comes into a quiescent state. Therefore, the response of transitioning the variable valve from an operating state to the quiescent state is improved.

Abstract: An electronic throttle control device in a internal combustion engine for a vehicle can be improved in maintainability and can be reduced in size. An electronic throttle control device in a V-type internal combustion engine for a vehicle has a fuel injection valve and throttle valves in an intake passage. A throttle driving motor controls the opening angle of each throttle valve according to the amount of operation of a throttle grip performed by an operator of the vehicle. The throttle driving motor is located outside a region surrounded by the throttle bodies that are respectively connected to all of intake ports as viewed in plan.

Abstract: In a multi-cylinder internal combustion engine, a hydraulic valve rest mechanism is mounted on a valve operating device, which performs open-close driving of an engine valve which is arranged in a cylinder head of an engine body having a plurality of cylinders in an openable-and-closable manner. The hydraulic valve rest mechanism is operated with an oil pressure that is controlled by a hydraulic control device so as to close and rest engine valves of a plurality of cylinders for bringing the cylinders into a rest state Therefore, the miniaturization of the multi-cylinder internal combustion engine along an axis of a crankshaft and can shorten a length of an oil passage which connects a hydraulic valve rest mechanism and a hydraulic control device. A hydraulic control device is arranged on an engine body directly above a portion thereof corresponding to a cylinder that is expected to assume a cylinder rest state.

Abstract: A multicylinder internal combustion engine, which can simplify its control and is advantageous against thermal loads or vibrations includes a cylinder head with intake valves and exhaust valves arranged therein. Valve actuators are provided for openably operating the intake valves and exhaust valves, respectively. A cylinder head cover forms, in combination with the cylinder head, a valve actuator chamber with the valve actuators accommodated therein. At least some of the valve actuators are deactivatable to disable their corresponding cylinders. The multicylinder internal combustion engine is a V-shaped internal combustion engine provided with a front bank and rear bank. The cylinders on opposite ends in a direction of a crankshaft are set as full-time operating cylinders.

Abstract: An internal combustion engine includes a connecting rod that connects a crankpin and a piston. The connecting rod has first and second connecting rods, and a guide piston is disposed at a connecting portion between the first and second connecting rods. Deformed portions are formed on a lower end portion of a guide piston and on a balancer weight portion of a crankshaft in order to reduce the whole length of the connecting rod, whereby a bottom dead center of the guide piston is set to a lower position. The engine has improved thermal efficiency by reducing the distance between the crank portion and the piston, increasing the speed of behavior of the piston at a position near a top dead center to reduce thermal energy loss, and preventing generation of knocking.

Abstract: An internal combustion engine having cylinders capable of selectively resting during engine operation is capable of eliminating step increases in engine output when the number of operative cylinders is changed. The internal combustion engine includes a plurality of cylinders divided into two or more groups, at least some of the cylinders being restable. A throttle valve of each of the cylinders is independently operable on the basis of the group to which the cylinder belongs, and the number of resting cylinders is controlled according to the throttle grip opening. The throttle valve opening is different between the groups, except for the full opening condition and the full closure condition of the throttle valve, and an ECU is provided for opening the throttle valve of the next cylinder group before the throttle valve opening of the former cylinder group reaches the full opening condition.

Abstract: An internal combustion engine incorporating rest cylinders is provided which does not need a high response performance when operating a throttle valve and which can eliminate engine output variations as the number of operable cylinders changes. In the internal combustion engine, some of a plurality of cylinders is configured to rest during normal operation of the engine. The cylinders are divided into a plurality of cylinder groups, and each of the cylinders is provided with an independent throttle valve. An ECU for increasing the number of operative cylinder groups according to at least the throttle handgrip opening is provided. Also provided are motors for bringing the throttle valves in the cylinder in the rest state into a fully closed state on the basis of each cylinder group, a throttle valve position sensor, and the like.

Abstract: An internal combustion engine incorporating rest cylinders is provided which does not need a high response performance when operating a throttle valve and which can eliminate engine output variations as the number of operable cylinders changes. In the internal combustion engine, some of a plurality of cylinders is configured to rest during normal operation of the engine. The cylinders are divided into a plurality of cylinder groups, and each of the cylinders is provided with an independent throttle valve. An ECU for increasing the number of operative cylinder groups according to at least the throttle handgrip opening is provided. Also provided are motors for bringing the throttle valves in the cylinder in the rest state into a fully closed state on the basis of each cylinder group, a throttle valve position sensor, and the like.

Abstract: An internal combustion engine includes a connecting rod that connects a crankpin and a piston. The connecting rod has first and second connecting rods, and a guide piston is disposed at a connecting portion between the first and second connecting rods. Deformed portions are formed on a lower end portion of a guide piston and on a balancer weight portion of a crankshaft in order to reduce the whole length of the connecting rod, whereby a bottom dead center of the guide piston is set to a lower position. The engine has improved thermal efficiency by reducing the distance between the crank portion and the piston, increasing the speed of behavior of the piston at a position near a top dead center to reduce thermal energy loss, and preventing generation of knocking.

Abstract: A variable valve operating mechanism of a four-stroke internal combustion engine includes a slide pin energized by a pin spring in a direction while oil pressure acting on the slide pin in the opposite direction through oil pressure supply passages. The slide pin moves by controlling the oil pressure causing a stem contact surface and a stem through hole to selectively face a valve stem. The mechanism also includes an oil discharge passage including a discharge port which is opened to allow oil acting the slide pin to be discharged when the valve lifter is pressed by a valve operating cam to move for opening the valve. The mechanism is capable of quickly moving the slide pin upon the release of oil pressure when the valve comes into a quiescent state. Therefore, the response of transitioning the variable valve from an operating state to the quiescent state is improved.

Abstract: In a multi-cylinder internal combustion engine having throttle valves to be opened and closed by electric motors, output control is enabled in various ways according to the state of usage of an object to be driven by the multi-cylinder internal combustion engine with a simple structure with the scope of application of shared components being expanded to reduce the cost. In addition, a throttle body assembly is downsized in the direction of the arrangement of the cylinders. A multi-cylinder internal combustion engine includes a predetermined number of cylinders, a throttle body assembly including the throttle bodies formed with intake-air channels and throttle valves. The respective throttle valves are opened and closed by the electric motors provided independently for each throttle valve. Air-intake ports of the first and fourth cylinders are formed so as to approach a center plane in the direction of the arrangement as they approach entrances.

Abstract: An internal combustion engine having cylinders capable of selectively resting during engine operation is capable of eliminating step increases in engine output when the number of operative cylinders is changed. The internal combustion engine includes a plurality of cylinders divided into two or more groups, at least some of the cylinders being restable. A throttle valve of each of the cylinders is independently operable on the basis of the group to which the cylinder belongs, and the number of resting cylinders is controlled according to the throttle grip opening. The throttle valve opening is different between the groups, except for the full opening condition and the full closure condition of the throttle valve, and an ECU is provided for opening the throttle valve of the next cylinder group before the throttle valve opening of the former cylinder group reaches the full opening condition.

Abstract: In a multi-cylinder internal combustion engine having throttle valves to be opened and closed by electric motors, output control is enabled in various ways according to the state of usage of an object to be driven by the multi-cylinder internal combustion engine with a simple structure with the scope of application of shared components being expanded to reduce the cost. In addition, a throttle body assembly is downsized in the direction of the arrangement of the cylinders. A multi-cylinder internal combustion engine includes a predetermined number of cylinders, a throttle body assembly including the throttle bodies formed with intake-air channels and throttle valves. The respective throttle valves are opened and closed by the electric motors provided independently for each throttle valve. Air-intake ports of the first and fourth cylinders are formed so as to approach a center plane in the direction of the arrangement as they approach entrances.