Catalyst Protection Against Hydrocarbon Exposure

Abstract

A system to protect an after treatment system from the effects of hydrocarbon accumulation on a catalyst. An engine system microprocessor using software estimates the amount of hydrocarbon accumulation on the after treatment system based on engine system parameters and other parameters. The accumulated hydrocarbons can cause an exothermic event if the catalyst temperature is allowed to ramp up too quickly. Similarly, accumulated hydrocarbon can temporarily reduce after treatment system performance. In the case of SCR, the microprocessor can control a reductant injector to modulate the amount of reductant being injected into the after treatment system to control the amount of ammonia slip. Alternatively or in addition to, the microprocessor can communicate with proper electronic control modules to modulate the engine system parameters such as engine speed, fuel, and back pressure to control engine exhaust flow temperature during operation of the engine system.

We claim: 
     
         1 . A method of protecting an after treatment system from effects of hydrocarbon accumulation, comprising the steps of:
 receiving, at a microprocessor of an engine system, engine system parameters from a plurality of electronic control modules of the engine system;   estimating, with the microprocessor of the engine system, an amount of engine out hydrocarbon based on the engine system parameters;   receiving, from a memory, a correction factor that adjusts the estimated amount of engine out hydrocarbon;   estimating, with the microprocessor of the engine system, a hydrocarbon mass on the after treatment system of the engine system with the adjusted estimated amount of engine out hydrocarbon; and   modulating, with the microprocessor of the engine system, a reductant that is applied to the after treatment system of the engine system based on the estimated hydrocarbon mass.   
     
     
         2 . The method of protecting of  claim 1  further comprising the step of controlling a gradual engine ramp up, with the microprocessor of the engine system that is communicating with a first electronic control module of the plurality of electronic control modules, based on the estimated hydrocarbon mass. 
     
     
         3 . The method of protecting of  claim 2  further comprising preventing an exothermic event in the after treatment system by controlling the gradual engine ramp up. 
     
     
         4 . The method of protecting of  claim 1 , wherein the correction factor is a manifold correction factor. 
     
     
         5 . The method of protecting  claim 1 , wherein the engine system parameters are selected from an amount of fuel, an engine speed, an engine timing, a total mass exhaust flow, a crank mode, an injection amount, an inlet manifold pressure, an inlet manifold temperature, a coolant temperature, an ambient temperature and an ambient pressure. 
     
     
         6 . The method of protecting of  claim 1 , wherein the estimated amount of engine out hydrocarbon includes a mass rate for engine hydrocarbon at startup or various engine hydrocarbon run mode. 
     
     
         7 . The method of protecting of  claim 1 , wherein the microprocessor communicates with a reductant injector to modulate the applied reductant. 
     
     
         8 . The method of protecting of  claim 2  further comprising the step of receiving, with the microprocessor, sensor information from a sensor. 
     
     
         9 . The method of protecting of  claim 8 , wherein the sensor is a throttle position sensor. 
     
     
         10 . The method of protecting of  claim 9 , wherein the step of controlling the gradual engine ramp up allows the engine to gradually warm up regardless of a position of a throttle sensed by the throttle position sensor. 
     
     
         11 . The method of protecting of  claim 1 , wherein the step of controlling engine ramp up includes controlling an amount of fuel being injected into the engine. 
     
     
         12 . A method of protecting an after treatment system from effects of hydrocarbon accumulation, comprising the steps of:
 receiving, at a microprocessor of an engine system, engine system parameters from a plurality of electronic control modules of the engine system;   estimating, with the microprocessor of the engine system, an amount of engine out hydrocarbon based on the engine system parameters;   receiving, from a memory, a correction factor that adjusts the estimated amount of engine out hydrocarbon;   estimating, with the microprocessor of the engine system, a hydrocarbon mass on the after treatment system of the engine system with the adjusted estimated amount of engine out hydrocarbon; and   controlling gradual exhaust temperature ramp up, with the microprocessor of the engine system that is communicating with a first electronic control module of the plurality of electronic control modules, based on the estimated hydrocarbon mass.   
     
     
         13 . The method of protecting of  claim 12  further comprising modulating, with the microprocessor of the engine system communicating with a reductant injector, a reductant that is applied to the after treatment system of the engine system. 
     
     
         14 . The method of protecting of  claim 12  further comprising preventing an exothermic event in the after treatment system by controlling step. 
     
     
         15 . The method of protecting of  claim 12 , wherein the correction factor is a manifold correction factor. 
     
     
         16 . The method of protecting of  claim 12 , wherein the estimated amount of engine out hydrocarbon includes a mass rate for engine hydrocarbon at startup or various engine hydrocarbon run mode. 
     
     
         17 . The method of protecting of  claim 12  further comprising the step of receiving, with the microprocessor of the engine system, sensor information from a throttle position sensor. 
     
     
         18 . The method of protecting of  claim 17 , wherein the step of controlling the gradual engine ramp up allows the engine to gradually warm up regardless of a position of a throttle sensed by the throttle position sensor. 
     
     
         19 . A system that protects an after treatment system of a vehicle from the effects of hydrocarbon accumulation, comprising:
 means for processing that communicates with a hydrocarbon estimation software stored on means for storing of an engine system computer;   means for injecting configured to inject a reductant into the after treatment system; and   means for interfacing that allows the means for processing to communicate with the means for injecting, wherein the means for processing executes the hydrocarbon estimation software to perform the steps of:   receiving, at the means for processing, engine system parameters from a plurality of electronic control modules of the engine systems;   estimating, with the means for processing, an amount of engine out hydrocarbon based on the engine system parameters;   receiving, from the means for storing, a correction factor that adjusts the estimated amount of engine out hydrocarbon;   estimating, with the means for processing, a hydrocarbon mass on the after treatment system of the engine system with the adjusted estimated amount of engine out hydrocarbon; and   modulating, with the means for processing controlling the means for injecting, the reductant that is applied to the after treatment system of the engine system.   
     
     
         20 . The system of  claim 19 , wherein the estimated amount of engine out hydrocarbon includes a mass rate for engine hydrocarbon at startup or various engine hydrocarbon run mode.