Piston-type internal combustion engine

An internal combustion engine operable through induction, compression, expansion and exhaust strokes, comprising:

• a main cylinder and a main piston movable therein;
• an auxillary cylinder and an auxillary piston movable therein;
• the inner ends of the two cylinder being in communication with each other and defining a common chamber with their respective pistons;
• means including a fuel intake valve for effecting the induction of gases into said common chamber;
• a control member movable to control the engine output;
• a variable valve timing device controlling the timing of the intake valve;
• a coupling between said movable control member and the variable valve timing device effecting a delay in the closing of the intake valve in response to the movement of the control member, which delay is increased when the control member is moved to lower the engine output and decreased when the control member is moved to raise the engine output;
• said auxillary piston being floatingly displaceable in its auxillary cylinder to increase or decrease the volume of the common chamber;
• a spring urging the auxillary piston to its innermost position within the auxillary cylinder;
• and limiting means controlled by said control member and acting on said auxillary piston independently of said spring for limiting the outermost position of the auxillary piston within its auxillary cylinder to increase or decrease the volume of said common chamber in accordance with the engine output so as to provide a substantially constant compression ratio and substantially complete exhaust during all loads.