| 摘要 |
A method and apparatus for controlling and improving the air-fuel ratio of a gas engine by controlling the air-fuel ratio on an exhaust purifying apparatus such as a three way catalyst in use with the gas engine. The method involves the steps of modulating a vibrational drive current for driving a bypass value 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 and a pressure sensor. The main oxygen sensor being installed on an up-stream side relative to the three way catalyst interposed on an exhaust line of the gas engine, and the pressure sensor being installed on an intake line in communication with a mixer; detecting distortion of responded waveforms of signals transmitted from a sub oxygen sensor, which sensor is installed on a down-stream side of the three way catalyst; and controlling the drive current so as to remove the detected distortions, in order to help optimize the air-fuel ratio of the gas engine. The invention thus helps in optimizing control of the air-fuel ratio and helps in the purification efficiency of the gas engine exhaust.
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