Abstract

A recirculating and recombustion type of exhaust gas purification system for a compression ignition engine includes an expansion manifold communicating with auxiliary combustion chambers of each cylinder through separate passages. Cam operated valves are located in each of the separate passages. The exhaust gas in an auxiliary combustion chamber is expanded into the manifold through one of the cam operated valves and is then drawn into the auxiliary combustion chamber of another cylinder whose piston is near the bottom of its intake or suction stroke via another open cam operated valve. The cam operated valves are actuated by hydraulic tappets which are controlled by a solenoid control valve. The solenoid control valve is energized under conditions of high load operation of the engine and, as a result, a hydraulic path is established which allows oil supplied to the tappets to return to the sump. Under this condition, the cam operated valves do not open.