Abstract:
The present invention is a turbocharger ( 18 ) and control system based strategy to control exhaust gas filters ( 30 ) for aftertreatment regeneration. The air handling system ( 10 ) uses the variable turbine geometry (VTG) of the turbine ( 20 ) and a compressor ( 22 ) flow control bleed valve ( 24 ) to drive pressurized intake air into the exhaust. The oxygen rich exhaust gas can then be mixed with fuel and combusted. Increasing the temperature of the exhaust gas will combust the excess exhaust gas emissions and reduce the pressure drop across the filter ( 30 ). This system ( 10 ) can be used under any operating conditions so as to be available to combust the excess exhaust gas emissions when needed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/738,158, filed Nov. 18, 2005. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to turbocharged vehicles and more particularly to a device for secondary combustion in a vehicle exhaust system, the intended purpose of which is to provide heat for regeneration of catalyst and/or incineration of deposits in a particle trap. The device of the present invention is capable of being operated completely independent of engine operation, and is particularly suitable for turbocharged diesel-powered vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Turbochargers are commonly used to significantly increase the power of an internal combustion engine or a diesel engine in a vehicle. A typical problem that exists with the use of turbochargers is the increase of exhaust emissions comprising of particulate matter (PM), hydrocarbons (HC) and oxides of nitrogen (NOx). Many diesel engines are being developed with aftertreatment systems to reduce emissions of PM, HC and NOx. 
         [0004]    These systems often include downstream filters and traps to store the unwanted by-products of combustion until a regeneration cycle can be initiated. A regeneration cycle is a process in which excess emissions of PM, HC, and NOx are “burned off.” Regeneration cycles typically require a specific temperature range and/or exhaust gas oxygen concentration to be effective, and operate for extended periods of time. Typically, during normal operating conditions, i.e., when the engine has been running to generate enough heat and is operating at a high enough speed, the amount of heat and oxygen necessary to combust the excess exhaust emissions is provided and the excess exhaust emissions will automatically combust, or burn off. Combustion of these excess exhaust emissions is important because build-up of PM, HC, and NOx can block the flow of exhaust gas, thus building up pressure in the exhaust line and affecting engine performance. 
         [0005]    One difficulty with the requirements of a specific temperature range and oxygen concentration occurs during vehicle start up, e.g., when the engine has not reached its normal operating temperature, and another occurs during low-speed operation, such as when the vehicle is at a stop light and air flow through the system is not high enough to allow for the proper amount of oxygen to be present to combust the excess emissions automatically. During these types of conditions, the excess emissions can build up in the filter or trap. 
         [0006]    Accordingly, there exists a need for a new and improved air handling system for a turbocharger system for a vehicle. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is an air handling system for a turbocharger and control system based strategy to control exhaust gas filters for aftertreatment regeneration. 
         [0008]    The turbocharger-based regeneration system of the present invention uses variable turbine geometry (VTG) and a compressor flow control valve to drive pressurized intake air into the exhaust. The oxygen rich exhaust gas can then be mixed with fuel and combusted, increasing its temperature to the point where the filter regenerates and the PM is combusted as well. Variable turbine geometry is used to increase, compressor discharge pressure under any engine speed and load conditions. The excess compressor pressure and flow are diverted into the exhaust gas system upstream of the particulate filter. A variable orifice on the discharge side of the compressor regulates the volume flow and maintains the required engine intake manifold conditions. Transient operation of the engine during regeneration is accomplished through a closed-loop control of the VTG mechanism and compressor discharge orifice to maintain engine load and exhaust gas temperature. 
         [0009]    The present invention is an air handling system with aftertreatment for an exhaust gas turbocharger for eliminating excess particulate matter having an intake manifold for introducing air into the engine, an exhaust manifold for removing the exhaust gases away from the engine, a turbine which receives the exhaust gases from the exhaust manifold, and a compressor for receiving, compressing, and forcing air into an intake line. The present invention also includes a filter located in an exhaust gas conduit for capturing excess exhaust gas particulate matter in the exhaust gases, a fuel source connected to a fuel pump through the use of a fuel line, and an ignition source positioned in a relationship with the fuel source such that the ignition source can ignite the fuel introduced into the exhaust gas conduit from the fuel source. A bleed valve is mounted inside the intake pipeline and connected to the exhaust gas conduit which introduces fresh air from the intake pipeline into the exhaust gas conduit to mix with the fuel introduced by the fuel source. Once the fresh air and fuel are mixed inside the exhaust gas conduit, the ignition source creates a spark, producing a combustion flame, burning off the exhaust gas particulate matter that has accumulated on the filter. 
         [0010]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0012]    The FIGURE is a diagram of an exhaust gas aftertreatment system, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0014]    Referring to the FIGURE, an air handling system  10  is generally shown with aftertreatment for an exhaust gas turbocharger for use in an internal combustion engine. The engine  12  includes an intake manifold  14  and an exhaust manifold  16  for conducting exhaust gas emissions away from the engine  12 . The exhaust manifold  16  is operably associated with a turbocharger, generally shown at  18 , having an actuator  19  and a turbine  20  which receives the exhaust gases from the exhaust manifold  16 . The turbine  20  can be a variable turbine geometry (VTG) turbine having an actuator  19  connected to the turbine  20  by a link  21 . The turbine  20  having variable turbine geometry can be of any type. The VTG turbine  20  is controlled by the actuator  19  and the link  20 . As the turbine  20  rotates from the exhaust gas flow the turbine  20  powers a compressor  22 . The compressor  22  receives, compresses, and forces fresh air through the bleed valve  24 . 
         [0015]    The present invention also includes an ignition source, which in this case is an igniter  26  for producing a spark. The igniter  26  is located in proximity to a fuel source, or fuel injector  28 . Both the igniter  26  and the fuel injector  28  are operably associated with a filter  30 . The filter  30  captures excess exhaust gas emissions such as particulate matter (PM) that has not burned off during the normal operation of the engine  12 . The filter  30  is located inside a muffler  32 . The muffler  32  delivers the exhaust gas into the atmosphere. 
         [0016]    The present invention also includes a fuel pump  34 , for delivering fuel to the fuel injector  28 , and is controlled by the vehicle&#39;s electronic control unit (ECU)  36 . The bleed valve  24  is located in an intake conduit  38 , and can divert some or all of the compressed fresh air from the compressor  22  into the intake manifold  14 . The fuel injector  28  and the fuel pump  34  are connected by a fuel line  40 , in which the fuel pump  34  delivers fuel to the fuel injector  28  when commanded to do so by the ECU  36 . The igniter  26  and the fuel injector  28  are located inside of an exhaust gas conduit  42 . Exhaust gas flows out of the engine  12 , is collected by the exhaust manifold  16 , and fed through the turbine  20  and into the exhaust gas conduit  42 . The exhaust gas then flows into the muffler  32  where the filter  30  collects any exhaust gas PM that did not burn off when combusted in the engine  12 . 
         [0017]    Under normal operation of the engine  12 , fuel is injected into the engine by the fuel pump  34 . The fuel pump  34  is controlled by the electronic control unit (ECU)  36 . The ECU  36  also controls the aftertreatement system by monitoring the condition of the muffler  32 , the filter  30 , and the fuel injector  28 . Monitoring the fuel injector  28  can be accomplished by using a fuel pressure regulator (not shown) for monitoring the correct fuel pressure going into the engine  10  or the injector  28 . 
         [0018]    The igniter  26  can be a spark plug or some other type of device which can produce the necessary spark to ignite the air-fuel mixture in the combustion chamber. As fuel is injected into the exhaust gas conduit  42 , the turbulence of the hot exhaust gases exiting the turbine  20  disperses the fuel inside the exhaust gas conduit  42 . Fresh air is introduced into the exhaust gas conduit  42  by bleed valve  24 . The bleed valve  24  is located in connection with conduit  38 . Conduit  38  delivers compressed air from the compressor  22  to intake manifold  14 . When the bleed valve  24  is opened, fresh air is diverted inside the conduit  38  into exhaust gas conduit  42 . The swirling air-fuel mixture is ignited within the exhaust gas conduit  42 , thereby producing a combustion flame. The result is the combustion flame increases the temperature of the exhaust gases flowing toward the filter  30  located inside the muffler  32 , causing any excess exhaust emissions to combust. 
         [0019]    The filter  30  may be comprised of ceramic material to withstand the severe heat of the exhaust gases, or may be comprised of some other high-temperature resistant material capable of collecting PM contained in the exhaust gas. 
         [0020]    The ECU  36  also preferably has control over the operation of the regeneration cycle in the aftertreatment system. The volume of excess exhaust emissions may be determined by reading the pressure differential on each side of the filter  30 . For instance, a pressure sensor can be placed upstream of the filter  30 , as well as downstream of the filter  30 , and the pressure differential can be measured between the two sensors. If the pressure differential reaches a certain predetermined value such that the amount of exhaust emissions begins to affect the performance of the engine  12 , the ECU  36  will activate the fuel injector  28  and the igniter  26  to produce the combustion flame, thus causing any excess exhaust emissions that have built up on the filter  30 , such as PM, to combust and burn off. Once the excess emissions have burned off, the ECU  36  will read that the pressure change across the filter  30  is acceptable, and de-activate the fuel injector  28  and the igniter  26 . It should be noted that instead of reading the pressure drop across the filter  30 , thermocouples or some other temperature reading devices could be used to sense the change in temperature across the filter  30 . Because the combustion flame increases the exhaust gas temperature, once the temperature is similar on both sides of the filter  30 , the exhaust gas will be hot enough to burn off any excess exhaust emissions that may have accumulated on the filter  30 . 
         [0021]    In operation, the exhaust gas flows from the engine  12 , and into the exhaust manifold  16 . The exhaust gas pressure then begins to activate the turbine  20 , which in turn drives compressor  22 . After the exhaust gases flow out of the turbine  20 , they flow through the exhaust gas conduit  42 , and then into the muffler  32 . As the exhausts gases flow through the muffler  32 , the filter  30  captures any excess exhaust emissions, such as PM, that did not burn off upon combustion in the engine  12 . 
         [0022]    Under normal operating conditions, when the exhaust gas is hot enough, the PM will bum off, i.e. combust, because of the heat from the exhaust gas. When the exhaust gas temperature is not high enough to burn off the excess PM, the PM will build up on the filter  30 . This build up causes a pressure build up, or backpressure, of the exhaust flow gases in the exhaust gas conduit  42 . The ECU  36  reads the pressure change across the filter  30 . If the pressure reaches a certain predetermined value, the ECU  36  triggers the activation of the fuel injector  28  and the igniter  26 . PM is burned off by the fuel injector  28  injecting fuel into the exhaust gas conduit  28 . As this occurs, bleed valve  24  opens up, allowing for fresh air to flow into the exhaust gas conduit  42 . With air and fuel in the exhaust gas conduit  42 , the igniter  26  introduces a spark, which ignites the air-fuel mixture, burning off any excess PM that has built up on the filter  30 , eliminating any backpressure resulting from the PM buildup inside the muffler  32 . The pressure reading by the ECU  36  can be independent of engine operating conditions. The ECU  36  can also be programmed to activate the aftertreatment system at a specified time interval, with the specified time interval being the maximum allowable time interval between activations. 
         [0023]    The igniter  26  can be powered by the vehicle battery, which is typically 12 volts, or it can be powered by some other device capable of providing an electric current to the igniter  26 , such as a separate battery. Once the aftertreatment cycle is started, the igniter  26  can be deactivated, and the combustion flame will remain continuous as long as the fuel injector  28  continues to supply fuel into the exhaust gas conduit  42 . Once the aftertreatment cycle is completed, the fuel injector  28  is deactivated, and the bleed valve  24  is closed, such that all the fresh air is directed into the intake manifold  14 . 
         [0024]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.