Two stroke cycle internal combustion engines

Abstract From the Canadian patent

A two-stroke spark ignited engine (10) with direct fuel injection (18) and an exhaust gas treatment catalyst. A separate catalyst unit (23 123, 223) is provided for each, combustion chamber (11) and is located at or adjacent each exhaust port (15) from that chamber and that during a cycle of each combustion chamber (11) the catalyst unit (23 123, 124) of that combustion chamber ( 23 123, 223) is exposed, only to exhaust gases which change from chemically reducing to chemically oxidising during the cycle An engine which has exhaust gases which are overall chemically oxidising can this nevertheless have the NOx constituents of the gases reduced.