This invention relates generally to an internal combustion engine and, more particularly, to an exhaust gas regenerator/particulate trap for an internal combustion engine.
An exhaust gas recirculation (EGR) system is used for controlling the generation of undesirable pollutant gases and particulate matter in the operation of internal combustion engines. Such systems have proven particularly useful in internal combustion engines used in motor vehicles such as passenger cars, light duty trucks, and other on-road motor equipment. EGR systems primarily recirculate the exhaust gas by-products into the intake air supply of the internal combustion engine. The exhaust gas, which is introduced to the engine cylinder, reduces the concentration of oxygen therein, which in turn lowers the maximum combustion temperature within the cylinder and slows the chemical reaction of the combustion process, thereby decreasing the formation of nitrous oxides (NOx). Furthermore, the exhaust gases typically contain unburned hydrocarbons, which are burned on reintroduction into the engine cylinder, which further reduces the emission of exhaust gas by-products which would be emitted as undesirable pollutants from the internal combustion engine.
In many EGR applications, the exhaust gas is diverted by an EGR valve directly from the exhaust manifold. The percentage of the total exhaust flow which is diverted for reintroduction into the intake manifold of an internal combustion engine is known as the EGR flow rate of the engine.
Some internal combustion engines include turbochargers to increase engine performance, and are available in a variety of configurations. For example, fixed housing turbochargers have a fixed exhaust inlet nozzle that accelerates exhaust gas towards a turbine wheel, which in turn rotates a compressor. Also, a variable nozzle turbocharger (VNT) has a variable nozzle having a ring of a plurality of variable vanes which are controlled to change the cross sectional area through which the exhaust gases pass to reach the turbine. In a VNT, the smaller the nozzle opening, the faster the gas velocity to the turbine, and in turn, the higher the boost. Still further, it is known to provide a turbocharger having two independent compressors, which is known as a double sided compressor.
When utilizing EGR in a turbocharged diesel engine, the exhaust gas to be recirculated is often removed upstream of the exhaust gas driven turbine associated with the turbocharger. The recirculated exhaust gas is typically introduced to the intake air stream downstream of the compressor and air-to-air after-cooler (ATAAC). Reintroducing the exhaust gas downstream of the compressor and ATAAC is preferred in some systems due to the reliability and maintainability concerns that arise if the exhaust gas passes through the compressor and ATAAC.
The recirculated exhaust gas includes particulate matter that can adversely affect the performance of the internal combustion engine by contaminating the intake air stream with the particulate matter. As disclosed in U.S. Pat. No. 5,617,726, a filter can be used to remove particulate matter from the exhaust gas that is being fed back to the intake air stream for recirculation. However, such filters are prone to clogging and must be periodically removed for cleaning.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.
In one aspect of the invention, an exhaust gas regenerator/particulate capture system is provided having a first particulate trap and a second particulate trap. The first particulate trap has a first particulate filter and the second particulate trap has a second particulate filter. A regenerator valve is provided having a valve member, an EGR inlet port, a purge air outlet port, a first particulate trap port and a second particulate trap port. The first particulate trap port is connected in fluid communication with a fluid port of the first particulate trap and a second particulate trap port is connected in fluid communication with a fluid port of the second particulate trap. The valve member is operable between a first position and a second position. When the valve member is in the first position, the EGR inlet port is connected in fluid communication with the first particulate trap and the purge air outlet is connected in fluid communication with the second particulate trap. When the valve member is in the second position, the EGR inlet port is connected in fluid communication with the second particulate trap and the purge air outlet is connected in fluid communication with the first particulate trap.
In another aspect of the invention, a method of filtering EGR gases is provided having the steps of: establishing an EGR gases fluid flow; establishing a compressed air fluid flow; positioning a valve member in a first position to effect the EGR gases fluid flow in a first direction through a first particulate trap and to effect a compressed air fluid flow in a second direction opposite to the first direction through a second particulate trap; and positioning the valve member in a second position to effect the EGR gases fluid flow in the first direction through the second particulate trap and to effect the compressed air fluid flow in the second direction opposite to the first direction through the first particulate trap.