Abstract:
Methods and systems for operating a glow plug are disclosed. In one example, current supplied to a glow plug can be controlled to promote combustion stability of a cylinder after an engine start. Engine feedgas hydrocarbons may be reduced during conditions where combustion stability may be otherwise reduced to reduce tailpipe emissions.
Abstract:
Systems and methods are provided for operating a particulate matter retaining system having at least a first and a second filter, coupled to an engine intake. One example method comprises, during a first condition, operating in a first mode with the first filter storing particulate matter and the second filter releasing stored particulate matter. The method further comprises, operating in a second mode with the first filter releasing stored particulate matter and the second filter storing particulate matter, the exhaust gas flowing in an opposite direction as compared to the first mode. The method further comprises, operating in a third mode with both the first and the second filter storing particulate matter. During the modes, at least some tailpipe gas is drawn from between the first and second filters for expulsion to the atmosphere.
Abstract:
A method of operating an engine system is described in which a back-pressure valve of a low pressure EGR system can be modulated at a lower frequency during an EGR operation, and at a higher frequency when additional exhaust gas sensing is requested. Back-pressure valve modulation can therefore be used to promote exhaust gas mixing while providing EGR. Exhaust gas constituents in the mixed exhaust gas can then be sensed with higher accuracy by downstream exhaust gas sensors.
Abstract:
A method of operating an engine system is described in which a back-pressure valve of a low pressure EGR system can be modulated at a lower frequency during an EGR operation, and at a higher frequency when additional exhaust gas sensing is requested. Back-pressure valve modulation can therefore be used to promote exhaust gas mixing while providing EGR. Exhaust gas constituents in the mixed exhaust gas can then be sensed with higher accuracy by downstream exhaust gas sensors.
Abstract:
Various systems and methods are described for controlling a selective catalytic reduction system coupled to an exhaust system of an engine, the selective catalytic reduction system including a catalyst and a diesel particulate filter. One example method comprises, before regeneration of the diesel particulate filter, adjusting an operating parameter to decrease an amount of ammonia stored in the SCR catalyst to a desired amount of stored ammonia, where the desired amount of ammonia storage is varied based on operating conditions, and initiating regeneration of the catalyst when the desired amount of stored ammonia is reached.
Abstract:
Systems and methods are provided for operating a particulate matter retaining system, comprising at least a first and a second filter, coupled to an engine intake. One example method comprises, during a first condition, operating in a first mode with the first filter storing particulate matter and the second filter releasing stored particulate matter, with exhaust gas flowing in a first direction through the filters. The method further comprises, operating in a second mode with the first filter releasing stored particulate matter and the second filter storing particulate matter, the exhaust gas flowing in a second, opposite, direction through the filters. The method further comprises, during a second condition, operating in a third mode with both the first and the second filter storing particulate matter. During all modes, at least some tailpipe gas is drawn from between the first and second filter for expulsion to the atmosphere.
Abstract:
A system and a method for effective NOx and particulate matter control in a diesel or other lean burn internal combustion engine is presented. The system includes a urea-based SCR catalyst having an oxidation catalyst coupled upstream of it and a particulate filter coupled downstream of the SCR catalyst. The particulate filter regeneration method teaches controlling operating conditions to bring the particulate filter temperature in the range where exothermic reaction between hydrocarbon and oxygen occurs. Once this is accomplished, extra hydrocarbons are injected into the exhaust gas entering the particulate filter where they combust and the resulting exotherm regenerates the filter. This method achieves effective particulate matter control while eliminating the risk of thermal damage to the upstream devices and minimizing regeneration fuel economy penalty.
Abstract:
A motor-vehicle engine system comprises a first DOC configured to receive exhaust from an engine and an SCR device coupled downstream of the first DOC in a flow direction of the exhaust. The system further comprises a second DOC coupled downstream of the SCR device. The system takes advantage of hydrocarbon sorption in the SCR catalyst that is a function of temperature to enable reduced hydrocarbon emissions via oxidation at the second DOC.
Abstract:
Methods and systems for operating a glow plug are disclosed. In one example, current supplied to a glow plug can be controlled to promote combustion stability of a cylinder after an engine start. Engine feedgas hydrocarbons may be reduced during conditions where combustion stability may be otherwise reduced to reduce tailpipe emissions.
Abstract:
A motor-vehicle engine system comprises a first DOC configured to receive exhaust from an engine and an SCR device coupled downstream of the first DOC in a flow direction of the exhaust. The system further comprises a second DOC coupled downstream of the SCR device. The system takes advantage of hydrocarbon sorption in the SCR catalyst that is a function of temperature to enable reduced hydrocarbon emissions via oxidation at the second DOC.