Reciprocating piston engine with pumping and power cylinders

A two stroke internal combustion engine comprising at least one unit having a pumping cylinder, a pumping piston reciprocally movable in said pumping cylinder, two power cylinders, a respective power piston reciprocally movable in each said power cylinder, each said power cylinder having an associated combustion chamber, the pumping piston reciprocating at a cycle speed twice that of the power pistons and said power pistons being phased about one stroke apart, a cylinder head closing top ends of all said cylinders, said head having two transfer ports therethrough enabling said pumping cylinder to communicate with said power cylinders, transfer valves controlling communication between the pumping cylinder and the power cylinders, at least two exhaust ports through said head allowing exhaust gases to flow from the power cylinders, exhaust poppet valves controlling the flow of the exhaust gases, at least one intake port through the head and communicating with the pumping cylinder, intake valve means associated with the intake port and allowing a major portion of intake charge to be induced into the pumping cylinder when the pumping piston is moving away from its top dead centre position and said pumping piston alternately transferring the charge into the power cylinders through the transfer ports as the pumping piston moves towards its top dead centre position, said pumping piston leads to the top dead centre position the power piston of the cylinder to which the charge is transferred, the transfer valves begin to open when the pumping piston is positioned between 70 degrees after top dead centre and 290 degrees after top dead centre and close when the pumping piston is positioned between 70 degrees before top dead centre and 70 degrees after top dead centre, the exhaust valves opening when the associated said power piston is at about or before its bottom dead centre position.