Muffler

DETAILED DESCRIPTION It is an object of the present invention to provide a muffler which can not only damp the combustion and exhaust sounds of the internal combustion engine, but also damp the noise produced in the muffler.
It is another object of the present invention to provide a muffler of which exhaust resistance is small.
According to the present invention, there is provided a muffler which comprises an inner shell having first and second expansion chambers which are coaxially arranged and connected to each other through a communicating passage; an outer shell spacedly covering the inner shell to define therebetween first, second, third and fourth isolated chambers, the first and second isolated chambers surrounding the first expansion chamber, while, the third and fourth isolated chambers surrounding the second expansion chamber; first means connecting the first expansion chamber with the first isolated chamber to allow the latter to show a sound damping effect; second means connecting the first expansion chamber with the second isolated chamber to allow the latter to show a sound damping effect; third means connecting the upstream and downstream portions of the second expansion chamber with the third isolated chamber to allow the latter to show a sound damping effect; fourth means connecting the upstream and downstream portions of the second expansion chamber with the fourth isolated chamber to allow the latter to show a sound damping effect; an inlet means leading to the first expansion chamber to introduce thereinto an exhaust issued from a noise source; and outlet means extending from the second expansion chamber to the open air to discharge the exhaust in the second expansion chamber into the atmosphere.