Exhaust gas treatment for a two stroke engine

摘要

PCT No. PCT/AU88/00343 Sec. 371 Date Jul. 5, 1989 Sec. 102(e) Date Jul. 5, 1989 PCT Filed Sep. 5, 1988 PCT Pub. No. WO89/02029 PCT Pub. Date Mar. 9, 1989.A two-stroke spark ignited engine (10) with direct fuel injection (14) and an exhaust gas treatment catalyst. A separate catalyst unit (23) 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) of that combustion chamber (11) is exposed only to exhaust gases which change from chemically reducing to chemically oxidizing during the cycle. An engine which has exhaust gases which are overall chemically oxidizing can thus nevertheless have the NOx constituents of the gases reduced.