Donaldson Comapny, Inc.

John Hamrin

Wayne M Wagner

Eivind Stenersen

John R Hiemstra

Theodore G Angelo

Ted J Wiegandt

Matthew Wesley Jones

A muffler is described for muffling both positive power and compression brake type engine retarders. The muffler includes an outer shell defining an internal volume. A first, inner, perforated wall is spaced from the outer shell and defines a first, annular, volume therebetween. A first volume of packing material is positioned within the annular volume. An inlet tube is oriented within the internal volume. In certain embodiments, the inner perforated wall circumscribes at least a portion of the inlet tube, and extends a distance of at least 25% of the axial length of the outer wall. Both single and dual muffler systems are described. Methods of use and operation are also provided.

Mufflers for use with engine retarders; and methods

A muffler for use with heavy duty trucks includes an outer wall defining an internal volume; an inlet tube oriented at least partially within the internal volume; an outlet tube construction oriented at least partially within the internal volume and including a diverging section and a choke extension; and a first baffle structure securing the outlet tube construction within the internal volume. A ratio of the diverging section axial length to the choke extension axial length is preferably less than 3:1. The first baffle structure defines an aperture arrangement therein to permit gas flow communication therethrough. A ratio of the total open area of the aperture arrangement to the perimeter, cross-sectional area of the first baffle structure is between 1:50 and 1:500. The mufflers are particularly useful for attenuating low frequency noise associated with the internal volume of cabs or sleepers in heavy duty trucks.

Muffler arrangements and methods

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Bloomington, MN, United States of America

John Hamrin