The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Diesel engine operation involves combustion that generates exhaust gas. During combustion, an air/fuel mixture is delivered through an intake valve to cylinders and is combusted therein. After combustion, the piston forces the exhaust gas in the cylinders into an exhaust system. The exhaust gas may contain emissions such as oxides of nitrogen (NOx) and carbon monoxide (CO).
An exhaust treatment system is typically used to reduce vehicle emissions. A control module monitors engine operation and a dosing system selectively injects urea into the exhaust upstream from a catalyst. The treated exhaust reacts with the catalyst. A chemical reaction occurs that heats the catalyst and reduces emissions in the exhaust. More specifically, the chemical reaction decomposes the NOx and urea into separate elements. NOx decomposes into nitrogen and water. The urea decomposes into ammonia, which is stored on the surface of the catalyst.
A diesel particulate filter is also used in the exhaust system for diesel engines. The diesel particulate filter removes particulate matter from the exhaust gases. The particulate matter is often referred to as soot. A diesel-powered vehicle equipped with a functioning filter will emit no visible smoke from its exhaust pipe.
In addition to collecting the particulate matter, a method for cleaning the filter must exist. Some filters are disposable and must be removed. Other filters are designed to oxidize the accumulated particulate matter. One way to clean the filter is to operate the engine in a pre-determined way so that the exhaust gas temperatures are heated to a level above the soot combustion temperature. This is known as filter regeneration.
The diesel particulate filter is sensitive to overheating. If a diesel particulate filter is overheated, cracking or other damage to the particulate filter may occur.