Selective catalytic reduction (SCR) device control system

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, the exhaust gas containing oxides of nitrogen (“NOx”), carbon monoxide and hydrocarbons;
• an oxidation catalyst (“OC”) device in fluid communication with the exhaust gas conduit, the OC device having a front face, the OC device adsorbing hydrocarbons and is selectively activated to induce oxidation of the hydrocarbons in the exhaust gas;
• an electrically heated catalyst (“EHC”) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, wherein the EHC device is located within the OC device and is selectively activated to produce heat and induce further oxidation of the exhaust gas, the EHC device having an oxidation catalyst compound disposed thereon for converting nitrogen oxide (“NO”) to nitrogen dioxide (“NO2”), the EHC device being positioned downstream of the front face of the OC device such that hydrocarbons in the exhaust gas do not substantially interfere with the generation of NO2 by the EHC device, the EHC device being selectively activated to an EHC light-off temperature;
• an selective catalytic reduction (“SCR”) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the SCR device located downstream of the EHC device and the OC device, and wherein the SCR device is in communication with and receives and stores reductant from a reductant source, the SCR device being selectively activated to an SCR light-off temperature;
• a first temperature sensor and a second temperature sensor in fluid communication with the exhaust gas conduit, the first temperature sensor situated upstream of the SCR device and the second temperature sensor situated downstream of the SCR device;
• a hydrocarbon (“HC”) adsorber in fluid communication with the exhaust gas conduit and located upstream of both the EHC device, the OC device, and the SCR device, wherein the HC adsorber adsorbs hydrocarbons from the exhaust gas;
• a control module in communication with the EHC device and the internal combustion engine, comprising:
• a control logic for determining if the SCR device has a threshold value of reductant stored therein, wherein the threshold value of reductant is the amount of reductant needed to create a chemical reaction to convert the reductant and the oxides of nitrogen NOx in the exhaust gas into intermediates;
• a control logic for activating the reductant source if the SCR device has not stored the threshold value of reductant;
• a control logic for selectively activating the EHC depending on if the SCR device has achieved the SCR light-off temperature;
• a control logic for monitoring the first temperature sensor and the second temperature sensor;
• a control logic for calculating an SCR temperature profile based on signals from the first temperature sensor and the second temperature sensor;
• a control logic for determining if the SCR temperature profile of the SCR device is below the SCR light-off temperature;
• a control logic for activating the EHC device to the EHC light-off temperature if the SCR temperature profile of the SCR device is below the light-off temperature;
• and
• a control logic for deactivating the EHC device if the SCR temperature profile of the SCR device is above the SCR light-off temperature.