Passive valve assembly with elongated vane

Abstract

A passive valve assembly for a vehicle exhaust system includes an exhaust component that defines an exhaust gas flow path and a vane that is positioned within the exhaust gas flow path. The vane has an elongated body structure that has a greater height than width. The vane is positioned to provide a high percentage of coverage when closed but is able to pivot to a fully horizontal position when open to allow maximum flow.

Description

RELATED APPLICATIONS[0001]This application claims priority to provisional application No. 60 / 989,508 filed on Nov. 21, 2007.TECHNICAL FIELD[0002]The subject invention relates to a passive valve assembly in a vehicle exhaust system, and more particularly to a passive valve assembly that has an elongated vane to improve valve performance.BACKGROUND OF THE INVENTION[0003]Exhaust systems are widely known and used with combustion engines. Typically, an exhaust system includes exhaust tubes that convey hot exhaust gases from the engine to other exhaust system components, such as mufflers, resonators, etc. Mufflers and resonators include acoustic chambers that cancel out sound waves carried by the exhaust gases. Although effective, these components are often relatively large in size and provide limited nose attenuation.[0004]Attempts have been made to improve low frequency noise attenuation by either increasing muffler volume or increasing backpressure. Increasing muffler volume is disadva...

AI Technical Summary

Benefits of technology

[0012]The vane is pivotable between a closed position where a maximum portion of the exhaust gas flow path is blocked by the vane and an open position where a minimum portion of the exhaust gas flow path is blocked by the vane. The closed position also defines a start position for the vane when there is no exhaust gas flow, or minimal exhaust gas flow. In one example, the exhaust gas flow path is 90%-97% blocked when the vane is in the start / closed position. Further, in one example configuration, the vane is positioned at a 20 degree start angle to provide a more rapid open area change. In this configuration, due to the elongated shape of the vane, the vane can be pivoted through a range of 20 to 90 degrees without interfering with walls of the exhaust component.

Problems solved by technology

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

Increasing muffler volume is disadvantageous from a cost, material, and packaging space perspective.

Increasing backpressure can adversely affect engine power.

Passive valves installed within mufflers are subjected to high temperatures, which limit the passive valve's effectiveness from material and cost perspectives.

By-pass configurations are also disadvantageous from material cost and packaging perspectives.

Further, when the passive valve is used in a by-pass pipe configuration, challenges are presented when the passive valve is moved toward a fully open position.

When the vane is moved toward the fully open position potential interference challenges are presented by the shape of the pipe itself.

Due to the pivot axis of rotation being mounted close to the wall surface of the pipe, when the vane is pivoted, interference between the pipe and the vane can limit opening of the valve assembly.

Limiting the opening angle is disadvantageous from a back pressure standpoint, in addition to failing to achieve a true fully open position for maximum flow.

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