Passive throttling valve outside of muffler

Abstract

An exhaust system includes an exhaust tube for conveying a heated exhaust flow from an engine. A valve is mounted at least partially within the exhaust tube for noise attenuation. The valve includes a bias member mounted outside of the engine exhaust tube within a heat transfer environment to maintain the bias member at a low temperature. The bias member biases the valve against the heat exhaust flow toward a predetermined position. The valve is mounted within a section of the tube having a smaller cross-sectional area and pivots into a larger cross-sectional area section of the exhaust tube to avoid interference with tube walls and provide a relatively large range of movement.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to vehicle exhaust systems and, more particularly, to a passive noise attenuation valve for use with an exhaust tube of the vehicle exhaust system.[0002]Exhaust systems are widely known and used with combustion engines. Typically, the exhaust system includes exhaust tubes that convey hot exhaust gases from the engine to a muffler. The muffler includes acoustic chambers that cancel out sound waves carried by the exhaust gases. Although effective, mufflers are often relatively large in size and provide limited nose attenuation.[0003]It has been proposed to utilize a valve within the exhaust tubes to provide noise attenuation. However, the proposed valves have numerous drawbacks that limit widespread use. For example, the temperature of the hot exhaust gas is approximately 1000° C., and therefore the valve requires actuation mechanisms that utilize special materials, that are relatively expensive, to withstand the severe temperatu...

AI Technical Summary

Benefits of technology

[0005]In one particular example, the valve is mounted within a section of the exhaust tube having a reduced cross-sectional area and is pivotable into a larger cross-sectional area section of the exhaust tube to avoid interference with tube walls and provide a relatively large range of movement.

Problems solved by technology

Although effective, mufflers are often relatively large in size and provide limited nose attenuation.

However, the proposed valves have numerous drawbacks that limit widespread use.

For example, the temperature of the hot exhaust gas is approximately 1000° C., and therefore the valve requires actuation mechanisms that utilize special materials, that are relatively expensive, to withstand the severe temperatures.

Moreover, since the valves are located within the exhaust tubes, they obstruct the flow of the exhaust gases and thereby limit effectiveness of the valve for noise attenuation.

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