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.
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.
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.
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.
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.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US12/33783 | 4/16/2012 | WO | 00 | 10/16/2014 |