| 摘要 |
<p>PURPOSE:To reduce HC in exhaust gas while preventing mixed gas from being concentrated by utilizing a sub-air intake passage provided for improving a combustion efficiency at the time of low loading and supplying secondary intake air via said sub-air intake passage into a combustion chamber at the time of deceleration. CONSTITUTION:Low speed fuel is drawn out at the time of the deceleration of an engine because a high negative pressure is produced in a main air intake passage in the downstream of a throttle valve 6, so that mixed gas has a tendency to be concentrated due to the evaporation, etc., of an fuel adhering to the wall. However at this juncture, air flows into a secondary air intake passage 18 since the high negative pressure is transmitted into the diaphragm chamber 22 of a negative pressure control valve 20 from a negative pressure port 24p to open the same valve 20, so that secondary intake air flows from an introducing port 18p into a sub-air intake passage 4. Accordingly, the high negative pressure in the main air intake passage 2 is turned down while leaning of the mixed gas is quickened, so that the exhaust of HC as a harmful component in exhaust gas caused by the concentration of the mixed gas can be reduced.</p> |
