Abstract: The pressure prevailing in a variable volume chamber which controls the compression ratio developed by a piston, is used control the movement of a valve which regulates the supply and draining of the chamber. During high load the high pressure is used to drain the chamber while under light load the lower pressure permits the chamber to be supplied with hydraulic fluid in a manner which tends to fill the same during induction phases and the like when the pressure in the cylinder is low.

Abstract: To induce high compression engine operation hydraulic fluid is fed into a variable volume chamber defined between an outer piston and an inner one which is reciprocatively disposed therein via a supply passage which includes a one-way valve. When low compression engine operation is required the pressure supplied to a valve chamber in which a spool valve is disposed is increased to the point whereat the spool valve moves to a position wherein the supply passage is closed and a drain and transfer passages are opened. The drain passage leads directly to the cylinder bore so as to enable the hydraulic fluid in the variable volume chamber to be vented unrestrictedly. The transfer passage permits a small amount of hydraulic fluid to flow through the variable volume chamber to the drain passage in a manner which cools the same and prevents degradation of the hydraulic fluid retained in the one-way valve and the like.

Abstract: At least one of two inlet valves provided per cylinder of a multi-cylinder internal combustion engine is operated using a variable valve timing device. This device is controlled in response to the load and rotational speed of the engine in a manner which reduces the lift of the valve at low engine speeds and stepwisely increases the same as the engine moves from one mode of operation to the other. In the event that only one valve is controlled this valve is selected to be the one other than that which generates swirl in the combustion chamber.

Abstract: There is provided an apparatus for driving intake and exhaust valves (12) of an internal combustion engine. The apparatus comprises a valve lift controlling means (16) connected to the valves to control the lift of the valves in response to the engine operating conditions, valve driving cams (13) fixed on a cam shaft (14) and being in contact with the valve lift controlling means (16), and a phase controlling means (23) arranged on the cam shaft (14) to control the relative rotational phase of the valve driving cams, i.e., the open and close timing of the valves (12) in response to the engine operating conditions.

Abstract: An internal to be at engine is provided with an engine cooling system by which the amount of cooling water introduced to a radiator is changed in accordance with engine load, so that the temperature of the cooling water is controlled to be at lower levels during a high engine load mode operation than during a low engine load mode operation. Additionally, an ignition timing control system of the engine is arranged to retard the ignition timing for a time period immediately after engine operation is shifted to the high engine load mode, thereby effectively preventing engine knock from arising when the engine operation is shifted to the high engine load mode.

Abstract: A variable valve timing system has a lever pivoted at one end on a piston reciprocally disposed in a cylinder and the other end in engagement with a poppet valve. A first cam cooperates with a second bell crank lever like cam which is eccentrically mounted on a rotatable shaft. Rotation of this shaft moves the second cam toward or away from the engine proper to vary the movement of the lever with which the second cam cooperates. The piston is biased out of the cylinder by a spring and maintained in position by hydraulic fluid introduced into the cylinder through a one way flow arrangement.

Abstract: In an air-fuel mixture supply device for an internal combustion engine, a butterfly-type throttle valve is disclosed whose upstream face is formed with a raised portion extending around the major of its periphery, but which is broken at least at the middle of the downstream part of the periphery of this upstream face. Thereby distribution of the air-fuel mixture is improved between the cylinders of a multi-cylinder engine.

Abstract: An EGR control system includes a plurality of ON-OFF air valves to control the amount of air admitted into a control passage extending from a source of constant vacuum to a control vacuum chamber upon which an EGR control valve is operated. The air valves are selectively energized by a controller containing a microcomputer wherein an exhaust gas control strategy is stored.