Briggs & Stratton, LLC

Parrish A Sandefur

Gary J Gracyalny

William M Kindness

A multi-pass catalytic converter/muffler uses a single catalytic support bed without increasing the overall size of the catalytic converter/muffler. The outer surface area of the catalytic support bed is disposed adjacent to the outer wall of the catalytic converter housing, with only the mat in between. Secondary air may be provided upstream before the exhaust gases make their first pass through the catalytic support bed, or after the first pass but before the second pass or even after the second pass.

Multi-pass catalytic converter

The catalytic muffler for small internal combustion engines has a venturi with a flattened profile formed from two stamped pieces, namely the muffler housing and the separator plate. This design eliminates the need for a separate piece of tubing or machined part, as is required in prior art round venturi devices. The catalytic muffler also includes a noise attenuator disposed upstream of the catalyst, thereby eliminating the back pressure which is otherwise applied to the venturi when the noise attenuator is disposed downstream of the catalyst. In addition, back pressure on the venturi is reduced by sizing the port in the separator plate and the exhaust port so that their respective cross sectional areas are substantially equal to the cross sectional area of the catalyst.

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Elm Grove, WI, United States of America

Parrish A Sandefur