Patent Publication Number: US-2015083096-A1

Title: Turbocharger turbine booster

Description:
BACKGROUND 
     Embodiments described herein concern improving performance of low emission internal combustion engines and maintaining the efficiency of engine emission control devices. In particular, the embodiments concern turbocharger transient response at low engine speed while improving the efficiency of an exhaust oxidation catalyst. 
     Air is introduced into many internal combustion engines by one or more turbochargers. Diesel engines may have two turbochargers, a low pressure turbocharger that provides air to the inlet of a high pressure turbocharger that provides air to the diesel engine. The turbochargers have compressors that discharge pressurized air. The turbocharger compressors are driven by turbocharger turbines that are driven by the engine exhaust. When exhaust flow to the turbocharger turbine decreases, the effectiveness of the turbocharger to provide pressurized air decreases. 
     One aspect of emission control of diesel engines is diverting exhaust gas into the engine air intake. Diverting exhaust into the engine air intake reduces the exhaust available to drive turbochargers and reduces the volume percent of oxygen in the engine exhaust. 
     SUMMARY 
     Embodiments concern introducing pressurized air into the exhaust system of a low emission internal combustion engine at one or more locations at which the air will increase the energy driving a turbocharger turbine. 
     Embodiments may also concern introducing air into the exhaust system of a low emission internal combustion engine at one or more locations at which the oxygen content of exhaust flow into a diesel oxidation catalyst is increased. 
     Embodiments may also concern providing a nozzle in a turbocharger turbine housing at a location at which high pressure air introduced through the nozzle will drive the turbocharger turbine without detrimentally increasing pressure that resists flow of exhaust to the turbocharger turbine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of air intake and exhaust systems of a diesel engine. 
         FIG. 2  is a schematic representation of air intake and exhaust systems of a diesel engine. 
         FIG. 3  is a cross section representation of a turbocharger turbine housing. 
         FIG. 4  is a schematic representation of another embodiment of air intake and exhaust systems of a diesel engine. 
         FIG. 5  is a schematic representation of another embodiment of air intake and exhaust systems of a diesel engine. 
         FIG. 6  is a schematic representation of another embodiment of air intake and exhaust systems of a diesel engine. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments described herein a low emission internal combustion engine. In one aspect, operating response of a low emission diesel engine is enhanced and the effectiveness of exhaust emission devices for low emission operation of the diesel engine is maintained. The embodiments are described hereinafter by reference to the accompanying drawings that show the embodiments. These concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein or to any aspect of those embodiments. 
       FIG. 1  shows an air intake and exhaust emission system  10  for a diesel engine  20 . Air  12  is drawn into the low pressure turbocharger compressor  14  which compresses the air  12  and urges it to and through an intermediate cooler  16  from which the air  12  flows to a high pressure turbocharger compressor  18  that further compresses the air  12  and urges it to a charge air cooler  24 . Air  12  passes from the charge air cooler  24  to an exhaust gas recirculation valve  26  by which exhaust gas  32  from the engine  20  is mixed with the air  12 . The mixture of air  12  and exhaust gas  32  is directed to the intake manifold  36  of the engine  20 . 
     Exhaust gas  32  leaving the engine  20  and flowing to the exhaust gas recirculation valve  26  is directed to an exhaust gas recirculation (EGR) cooler  38  from which cooled exhaust gas  32  is directed to the exhaust gas recirculation valve  26 . Exhaust gas  32  is also directed from the engine  20  to the high pressure turbocharger turbine  42  which drives the high pressure turbocharger compressor  18 . Exhaust gas  32  is directed from the high pressure turbocharger turbine  42  to the low pressure turbocharger turbine  44  which drives the low pressure turbocharger compressor  14 . 
     Exhaust gas  32  is then directed from the low pressure turbocharger turbine  44  to a diesel oxidation catalyst  46 . The diesel oxidation catalyst  46  catalyzes the oxidation of hydrocarbon and carbon monoxide gaseous pollutants in the exhaust gas  32 . Exhaust gas  32  is then directed to a particulate filter  48  that removes particulate matter from the exhaust gas  32 . The exhaust gas  32  is then discharged from the system  10 . 
     Diversion of exhaust gas  32  through the EGR cooler  38  decreases the exhaust energy available to drive the high pressure and low pressure turbocharger turbines  42  and  44 . During slow operation of the engine  20 , this diversion can limit the capacities of the high pressure turbocharger compressor  18  and the low pressure turbocharger compressor  14  to supply air to the engine  20  causing a lack of response to demands for increased energy from the engine  20 . 
       FIG. 2  shows an air intake and exhaust emission system  60  for a diesel engine  20 . A source of pressurized air  50  is provided. Air is directed from the source  50  to the high pressure turbocharger turbine  42  to supplement the energy of the exhaust  32  that drives the high pressure turbocharger turbine  42 . In addition to increasing the mass and energy of the flow of exhaust gas  32 , injecting air into the exhaust as  32  increases the oxygen in the exhaust gas  32  that is available for oxidation and thereby increases the effectiveness of the diesel oxidation catalyst  46  without increasing the engine combustion oxygen content. 
       FIG. 3  shows a cross section of a turbocharger turbine housing  54  that includes a turbine flow booster inlet  56 . A flow booster inlet  56  is positioned at a location that is separated from the exhaust inlet  62  and at which the wall  66  of the housing  54  is close to the turbine (not shown). The flow booster inlet  56  provides a flow path  64  for air introduced into the housing  54  that is directed tangential to the direction of rotation  68  of the turbine to drive the turbine at a location at which air flow through the inlet  56  impinges almost directly on the turbine and is directed to the outlet of the high pressure turbine  42 . Locating the turbine flow booster inlet  56  at this location causes the air that flows through the flow booster inlet  56  to drive the turbine and exit the high pressure turbocharger turbine  42  without causing undesired resistance to the exhaust flow entering the exhaust inlet  62 . 
       FIG. 4  shows another air intake and exhaust emission system  70  for a diesel engine  20 . A source of pressurized air  50  is provided. Air is directed from the source  50  to the low pressure turbocharger turbine  44  to supplement the energy of the exhaust gas  32  that drives the turbocharger turbine  44 . The low pressure turbocharger turbine  44  has turbocharger turbine housing  54  with a flow booster inlet  56 . As described for the system  60 , air is injected into the housing  54  to drive the turbine and to increase the oxygen in the exhaust  32  that is available for oxidation and thereby increases the effectiveness of the diesel oxidation catalyst  46 . 
       FIG. 5  shows an embodiment of an air intake and exhaust emission system  70 . As shown by  FIG. 5 , the source of pressurized air  50  may be a supercharger  72 . 
       FIG. 6  shows another air intake and exhaust emission system  80  for a diesel engine  20 . A compressor intake valve  82  is located between the charge air cooler  24  and the exhaust gas recirculation valve  26 . The compressor intake valve  82  diverts air  12  to a compressor pre-cooler  84 . Air  12  is directed from the compressor pre-cooler  84  to a compressor  86  that compresses the air  12  and urges the air  12  to high pressure turbocharger turbine  42  as described in the context of air intake and exhaust emission system  60 . Air  12  is also directed to a partial burner nozzle  88  that is located in the flow of exhaust gas  32  between the low pressure turbocharger turbine  44  and the diesel oxidation catalyst  46 . The partial burner nozzle  86  increases the temperature of the exhaust gas  32  flowing to the diesel oxidation catalyst  46  and the diesel particulate filter  48 . 
     The source of pressurized air  50  may be any apparatus that provides pressurized air such as the supercharger  72  and the compressor  86 . The compressor  86  may be any device that functions to compress air as described. The compressor  86  may be driven by one or more apparatus including electrically or mechanically. 
     The embodiments include a method for increasing the response of a turbocharged engine comprising providing a source of pressurized air and introducing pressurized air from the source of pressurized air into a flow of engine exhaust to a turbocharger turbine in response to a request for increased engine power. The pressurized air may be introduced into the flow of engine exhaust to a turbocharger turbine through a flow booster inlet in a housing of the turbocharger turbine. The source of pressurized air may be a supercharger. Air may be diverted from a flow into an intake of the turbocharged engine to the source of pressurized air and the source of pressurized air pressurizes the air diverted from the flow to the engine intake. Air may be provided air from a source of pressurized air into a flow of exhaust from a turbocharger to an oxidation catalyst. Air may be provided from the source of pressurized air to a partial burner nozzle located in a flow of exhaust from a turbocharger to an oxidation catalyst.