| 摘要 |
<p>The present invention relates to a method of controlling air-fuel ratio of a gas engine provided with a three-way catalyst, based on sensed oxygen concentration at the catalyst. In the present invention, there are the steps of: modulating (21) a periodic drive current for driving an intake by-pass valve (8) with waveforms such as rectangular wave, sinusoidal wave, triangular wave, etc., with predetermined periods and amplitudes, in response to signals transmitted from a main oxygen sensor (11) and a pressure sensor (6), said main oxygen sensor being installed up-stream of the three-way catalyst interposed in an exhaust line of the gas engine, and said pressure sensor being installed in an intake line from a gas-air mixer; detecting (23) distortions of responding waveforms of signals transmitted from a sub oxygen sensor (12), which sensor is installed down-stream of said three-way catalyst; and controlling said drive current so as to remove said distortions, in order to optimizing air-fuel ratio of the gas engine. By means of the present invention, the optimum control of the air-fuel ratio is achieved, and purification efficiency can be improved. <IMAGE></p> |
