Abstract: A V-type multiple cylinder air intake is being configured to improve the volumetric efficiency by utilizing the resonance effect while also eliminating the adverse influence of the resonance effect (residual resonance) when the engine is operating in regions of medium to high rotational speeds. The V-type multiple-cylinder air intake device has two collectors with one arranged on each bank of the V-type multiple-cylinder engine; a plurality of branch pipes extending from the collectors to a respective intake port of an opposite bank; and a plurality of crossover passages extending from the collectors to a respective branch pipes extending from the collector of the opposite bank.

Abstract: A V-type multiple cylinder air intake is being configured to improve the volumetric efficiency by utilizing the resonance effect while also eliminating the adverse influence of the resonance effect (residual resonance) when the engine is operating in regions of medium to high rotational speeds. The V-type multiple-cylinder air intake device has two collectors with one arranged on each bank of the V-type multiple-cylinder engine; a plurality of branch pipes extending from the collectors to a respective intake port of an opposite bank; and a plurality of crossover passages extending from the collectors to a respective branch pipes extending from the collector of the opposite bank.

Abstract: In a hydraulic pressure control system for an engine cylinder cutoff device through which a first group of cylinders are cut off with at least intake valves of engine valves included in the first group kept inactive, while a second group of cylinders are working, the system includes a valve mode switching mechanism being responsive to supply oil pressure for switching an operating mode of at least an intake valve of engine valves of each of the first group of engine cylinders from active to inactive. Also provided is a hydraulic pressure control valve regulating the supply oil pressure. A control unit incorporated in the system sets the supply oil pressure to a predetermined maximum pressure when initiating the inactive mode, and holds the supply oil pressure at a predetermined oil pressure lower than the predetermined maximum pressure before the inactive mode is released.

Abstract: A hydraulic control system for an internal combustion engine is provided which comprises a first hydraulic operating mechanism and a second hydraulic operating mechanism, the first hydraulic operating mechanism and the second hydraulic operating mechanism being operated independently by oil pressure of a common oil press source, and a circulation line that supplies pressure oil discharged from the first hydraulic operating mechanism to the second hydraulic operating mechanism.

Abstract: A hydraulic control system for an internal combustion engine is provided which comprises a first hydraulic operating mechanism and a second hydraulic operating mechanism, the first hydraulic operating mechanism and the second hydraulic operating mechanism being operated independently by oil pressure of a common oil press source, and a circulation line that supplies pressure oil discharged from the first hydraulic operating mechanism to the second hydraulic operating mechanism.

Abstract: In a hydraulic pressure control system for an engine cylinder cutoff device through which a first group of cylinders are cut off with at least intake valves of engine valves included in the first group kept inactive, while a second group of cylinders are working, the system includes a valve mode switching mechanism being responsive to supply oil pressure for switching an operating mode of at least an intake valve of engine valves of each of the first group of engine cylinders from active to inactive. Also provided is a hydraulic pressure control valve regulating the supply oil pressure. A control unit incorporated in the system sets the supply oil pressure to a predetermined maximum pressure when initiating the inactive mode, and holds the supply oil pressure at a predetermined oil pressure lower than the predetermined maximum pressure before the inactive mode is released.

Abstract: A valve mechanism of an internal combustion engine is of a type which has at least two cams for each intake (or exhaust) valve. One cam is shaped to allow the associated engine to exhibit a marked fuel saving characteristic and the other cam is shaped to also the engine to produce a higher torque at relatively low (or high) engine speed. Upon a cam switching between these cams, at least one of the cams is subjected to a phase change before and/or after the actual cam switching. As a result, the undesired shock at the cam switching is eliminated or at least minimized.

Abstract: A main rocker arm which is pivotally mounted on a rocker shaft has one or more sub-rocker arms pivotally mounted thereon. The main rocker arm is arranged to synchronously open and close two poppet valves. Each of the sub-rocker arms can be selectively locked to the main one by way of hydraulically operated plunger arrangements. The main rocker arm is provided with a roller type cam follower which follows a low speed cam. The sub-rocker arms are provided with followers which engage high or very high speed cams. Lost motion springs which maintain the sub-rocker arms in contact with the cams are mounted on the main rocker arm.

Abstract: In a valve train for an I.C. engine, a cam shaft has cams formed with compound curvatures which allow the valve timing to be altered while the engine is operating, to suit the engine driving conditions by shifting the cam shaft along its axis. To reduce the force necessary to shift the cam shaft along its axis the valve closure springs are replaced by closure cams. In some embodiments pivoting arrangements comprising a pair of ball and socket joints are provided to eliminate lateral sway of the rocker arms allowing precise adjustment of the valve timing when the cam shaft is shifted along its axis. In other embodiments the rocker arms are journalled on a rocker shaft provided with stops for preventing lateral sway. In some embodiments the closure rocker arms have cupped ends in which either the valve stem retainer or the valve stem seal is received.

Abstract: A rocker arm is pivotally mounted on a rocker shaft. A first cam follower such as a roller is provided on the rocker arm and arranged to cooperate with a low speed cam. A second cam follower is reciprocally mounted on the rocker arm and arranged to cooperate with a high speed cam. A locking arrangement for selective locking the second cam follower in place comprises three plungers which are each reciprocatively received in their own bore. One of the bores is formed in the second cam follower while the other two are formed in the rocker arm. When hydraulic pressure is applied to one end of one of the plungers and the high and low speed cam followers are in engagement with the base circles of the respective high and low speed cams, the plungers are axialy displaced against a return spring in a manner two project into an adjacent bore and induce interlocking.

Abstract: A variable valve timing type rocker arm arrangement is arranged so that, in the absence of sufficient hydraulic pressure to operate the interlocking mechanisms which switch the valve lift control from one cam follower to another, it defaults to a cam follower suited for low speed engine operation rather than one which is adapted to maximize fuel economy. During engine starts (when oil pump output is inherently low) the initial low speed cam follower defaulting improves aspiration and reduces the tendency for incomplete combustion to induce the formation of smoldering deposits on the spark plug electrodes. In the event of an actual hydraulic system malfunction, the defaulting enable the engine to produce enough torque to render the vehicle drivable.

Abstract: Main and sub-rocker arms mounted on a common shaft and pivotally supported on a cylinder head by a pivot formed at the end of an adjust screw which is provided at one of the main rocker arm. The main and sub-rocker arms are motivated by cams suited for low engine speed and high engine speed operation respectively. A hydraulically operated interlocking device which selectively locks the main and sub-rocker arms together, is controlled by a supply of hydraulic fluid by way of a passage structure formed in the adjust screw and a pivot seat in which the pivot is received.