Exhaust emission control in gaseous fuelled engines

摘要

PCT No. PCT/GB91/00634 Sec. 371 Date Dec. 16, 1992 Sec. 102(e) Date Dec. 16, 1992 PCT Filed Apr. 22, 1991 PCT Pub. No. WO91/16531 PCT Pub. Date Oct. 31, 1991.A fuel supply control for an internal combustion engine designed to run on gaseous fuel (LPG or CNG) utilizes a feedback loop from a lambda sensor in the exhaust gases to a moving coil (82) mounted on a diaphragm (34) of a diaphragm-actuated valve (24) controlling the flow of gaseous fuel to the engine. The coil (82) is similar to the speaker coil of an audio speaker, and moves concentrically of a fixed permanent ring magnet (86) to impart a variable bias on the diaphragm(34) in accordance with the oxygen content of the exhaust gas stream as sensed by the lambda sensor, to control the fuel or air-and-fuel supply to the engine in accordance with desired engine operation parameters. The control has a sufficiently rapid and positive response that it can maintain the free oxygen content in the exhaust gases at substantially 2% for continuous operation of a catalytic exhaust purifier at or nearly at optimum efficiency.