Tenneco Automotive Inc.

Low Cost, Low Weight Muffler

The purpose of a car’s muffler is to be part of the system that conveys hot exhaust gases from an engine manifold to a point of release, while controlling noise emanating from combustion and expulsion of hot gases from the engine, and suppressing structural vibrations expressed as noise. Because of these functions, mufflers have had significant structural mass as well as cost.

Tenneco Automotive has redefined not what mufflers do, but how they may be designed and constructed to do it. The result is this innovative low-cost low-weight muffler. The assignment they undertook was to design and produce a muffler that is lighter, cheaper, and with desirable (just as good or better) acoustic properties.

Mufflers have historically been made with laminated shells of 1.2 mm steel, with good stand-alone structural strength, in order both to hold up and to provide acceptable heat management and acoustics. With these constraints, mufflers have been reduced in weight by 20% by the savings here and there over the last five years, engineered by various suppliers. Cost has not been reduced much at all, partly due to material costs (thick-wall laminated steel).

The Tenneco low-cost low-weight muffler has been designed by intensive use of Tenneco’s Computer Aided Engineering (CAE), with the result that they have been able to design a single, thin walled muffler (0.7 mm) with a bead pattern that permits in-process welding, and with uncompromised, and even tunable, acoustics.

Tenneco integrated the muffler into the vehicle underbody, to avoid structure-borne noise, thus reducing allocated underbody design space as well. In addition, Tenneco is able to use its CAE to overcome the noise associated with single thin walls, and to tune muffler acoustics by using irregular, geometric embossing patterns in surface topology. Tenneco’s overall effort very cleverly results in a muffler that costs less, and takes another 20% out of muffler weight with just this one innovation.

Tenneco Automotive’s low cost, low weight muffler technology will shortly be applied by General Motors on one of its global vehicle platforms.