Partial wall-flow filter and diesel exhaust system and method

Abstract

A exhaust system and method for venting exhaust from an engine, such as a diesel engine, through an exhaust line coupled to the engine includes a first particulate filter disposed in the exhaust line and “close-coupled” with the engine, and a second particulate filter spaced a distance (d) from the first filter. The first particulate filter is “close-coupled” so that it operates in a passive regeneration mode to a greater extent than the second particulate filter. The first particulate filter may be a partial wall-flow filter including some plugged and some open channels. Some of the plugged channels may be plugged adjacent to an inlet end and others may be plugged adjacent to an outlet end. A partial wall-flow filter is also described having some unplugged flow-through channels and some plugged channels wherein some plugged channels are located adjacent to the inlet end and some are located adjacent to the outlet end.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates generally to wall-flow filters used to filter exhaust gases, and exhaust systems and methods incorporating such filters.[0002]Diesel exhaust systems may include, for example, a diesel particulate filters (DPFs) for removing particulates, such as soot from diesel exhaust. Where multiple DPFs are used to remove particulates, these DPFs are typically arranged in close proximity to each other and housed within a common enclosure, such as taught in US Pat. App. No. 2004 / 0161373. The most widely used DPFs are wall-flow filter. The conventional wall-flow filter consists of a ceramic honeycomb substrate having longitudinal, parallel cell channels formed by a plurality of intersecting porous walls. The ends of the cell channels are typically plugged with a ceramic plugging cement to form a checkered pattern of plugs at the end faces of the honeycomb substrate. The cell channels of the filter typically have some ends plugged at an...

AI Technical Summary

Benefits of technology

[0009]Other features and advantages of the invention will be apparent from the following description and the appended claims.

Problems solved by technology

Increase in pressure drop across the filter generally results in an increase in backpressure against the engine which, if not controlled, may lead to power loss.

On the other hand, “active” regeneration comes with a fuel economy penalty.

Additionally, there is the possibility of large temperature spikes during “active” regeneration which may be detrimental to the filter.

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