Internal combustion engine having diverter valve and separate passage for purging engine

In a fuel injected, internal combustion engine of the type having a single poppet valve for controlling the flow of air to the combustion chamber and exit of exhaust gases therefrom, an inlet passage for the supply of air under pressure;

• an outlet passage for exit of exhaust gases, said outlet passage communicating with said inlet passage as a continuation thereof;
• a further passage terminating at one end in said combustion chamber and at the other end at the junction of said inlet and outlet passages, said single poppet valve being arranged and operated to control the flow of gases through said further passage into and out of said combustion chamber in timed relation to rotation of the engine's crankshaft, all of said passages being circular in cross-sectional shape;
• a diverter valve selectively movable in timed relation with opening and closing of the poppet valve so as in one position to direct flow of pressurized air through the inlet passage into the combustion chamber and later, in another position, the flow of combustion gases from the combustion chamber through the outlet passage;
• and means controlling movement of said diverter valve from each of one position to another, the improvement comprising a secondary air passage to said combustion chamber in parallel flow relation with said inlet passage and arranged such that air flows therethrough into the combustion chamber when the diverter valve is in the exhaust position and the poppet valve is open.