Dual air circuit for exhaust gas treatment

Abstract

An exhaust treatment system for an engine includes a regeneration device being in receipt of exhaust from the engine and positioned upstream of a diesel particulate filter. A compressor provides a source of compressed air. An air / fuel nozzle is coupled to the regeneration device, in receipt of a fuel supply as well as the compressed air. The fuel and compressed air are forced through an orifice of the nozzle to atomize the fuel. A bypass line provides compressed air from the compressor to the regeneration device without passing through the orifice of the nozzle. A valve is operable to allow compressed air to flow through the bypass line when a predetermined condition exists.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION[0001]This patent application claims the benefit of U.S. Provisional Patent Application No. 61 / 437,896, filed Jan. 31, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto.FIELD OF THE INVENTION[0002]The present disclosure generally relates to exhaust gas treatment systems. More particularly, a dual circuit secondary air system cooperates with a diesel particulate filter regeneration device to improve emissions control.BACKGROUND OF THE INVENTION[0003]This section provides background information related to the present disclosure which is not necessarily prior art.[0004]Exhaust aftertreatment systems may include a diesel particulate filter for treating the exhaust of a diesel engine. In many applications, it may be beneficial to periodically regenerate or oxidize soot trapped within the diesel particulate filter. A regeneration device such as a burner may be positioned upstream of the diesel parti...

AI Technical Summary

Benefits of technology

The patent describes a method of treating exhaust from an engine by compressing air and using it to regenerate a device that filters out particulate matter. The method includes using a fuel and compressed air to a nozzle for ignition, and using an auxiliary path to provide compressed air to the regeneration device to reduce the load on the compressor. The technical effect is a more efficient and effective method of treating engine exhaust gases.

Problems solved by technology

As such, an exhaust aftertreatment system properly designed for operation at relatively low to moderate engine speeds may not optimally function at an upper range of engine speeds.

A resistance to flow at the outlet of the compressor may undesirably load the compressor and increase the operating temperature of the compressor.

By limiting the compressor output, the flow rate of secondary air through the burner nozzle may be insufficient to heat the high volume of exhaust flowing through the burner.

An undesirably low temperature at the diesel particulate filter inlet may result.

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