Patent ID: 6176347
Filing Date: 2001-01-23
Classification: F01N

Abstract:
A semi-active muffler for an internal combustion engine comprising:a case defining a closed space with a predetermined capacity, the case being partitioned into first, second, and third chambers;a first bypass pipe for communicating the first chamber with the third chamber; a second bypass pipe for communicating the second chamber with the third chamber;an inlet pipe for introducing exhaust gas into the first and second chambers;an outlet pipe for exhausting the exhaust gas introduced into the third chamber from the first and second chambers respectively through the first and second bypass pipes;a valve for selectively opening a downstream end of the second bypass pipe according to a pressure level within the second chamber; andbuffer means for reducing an impact and noise when the valve is opened and closed,wherein the buffer means comprises a gap kept between the valve and the downstream end of the second bypass pipe even when the valve is in a completely closed position.