Voltage control system for heating a selective catalyst reduction device

摘要

An exhaust gas treatment system for an internal combustion engine is provided. The exhaust gas treatment system includes an electrically heated catalyst (“EHC”) device in fluid communication with an exhaust gas conduit, a generator, a selective catalytic reduction (“SCR”) device, and a control module. The EHC device includes an electric heater and an EHC catalyst that is heated to an EHC light-off temperature. The generator is selectively operable in a target voltage mode to supply a target voltage to the electric heater. The target voltage represents a voltage required by the electric heater in order to maintain the EHC catalyst at a catalyst temperature. The SCR device is in fluid communication with the exhaust gas conduit. The SCR device is located downstream of the EHC device and includes an SCR catalyst that is selectively heated by the EHC device to a SCR light-off temperature.

主权项

1. An exhaust gas treatment system for an internal combustion engine, comprising:
an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine; an electrically heated catalyst (“EHC”) device in fluid communication with the exhaust gas conduit, the EHC device including an electric heater and an EHC that is heated to an EHC light-off temperature; a generator selectively operable in a target voltage mode to supply a target voltage to the electric heater, wherein the target voltage represents a voltage required by the electric heater in order to maintain the EHC at a catalyst temperature; a selective catalytic reduction (“SCR”) device in fluid communication with the exhaust gas conduit, wherein the SCR device includes an SCR catalyst that is selectively heated by the EHC device to a SCR light-off temperature; a hydrocarbon supply selectively activated to introduce hydrocarbons into the exhaust gas conduit; and an electronic control unit (“ECU”) in communication with the generator, the EHC device, the hydrocarbon supply, and at least one temperature sensor of the SCR device, the ECU configured to:
determine an SCR temperature of the SCR catalyst;determine whether the EHC is above the EHC light-off temperature and whether the SCR catalyst is below the SCR light off temperature; andoperate the generator in the target voltage mode based on determining that the EHC is above the EHC light-off temperature and the SCR catalyst is below the SCR light off temperature, wherein operating the generator in the target voltage mode comprises continuously monitoring one or more parameters of the exhaust gas treatment system and continuously controlling an output voltage of the generator based on the one or more parameters so as to responsively adjusting adjust the target voltage to maintain the catalyst temperature based the SCR temperature, wherein the catalyst temperature represents a temperature required by the EHC to sustain combustion of the hydrocarbons introduced into the exhaust gas conduit and sustain the SCR light-off temperature of the SCR catalyst so as to improve conversion efficiency of the SCR catalyst.