Controller for controlling oxides of nitrogen (NOx) emissions from a combustion engine

Abstract

A controller for controlling oxides of nitrogen (NOx) emissions from a combustion engine based on estimating a parameter for the engine. The controller capable of adjusting cylinder temperature based on the estimated parameter for controlling NOx emissions.

What is claimed:  
     
         1 . A method for controlling oxides of nitrogen (NO x ) emissions from a combustion engine, the method comprising, 
 estimating at least one parameter from the group of cylinder temperature and cylinder fraction;    detecting an engine operating point and determining at least one desired value for the at least one parameter based on the engine operating point;    comparing the estimated parameter to the at least one desired value for the at least one parameter; and    calculating an emissions control signal that increases cylinder temperature when the estimated parameter is below the desired value of the at least one parameter, and that decreases cylinder temperature when the estimated parameter is above the desired value of the at least one parameter.    
     
     
         2 . The method of  claim 1  further comprising estimating the at least one parameter as a function of estimating cylinder pressure.  
     
     
         3 . The method of  claim 2  wherein the estimating function for estimating cylinder pressure comprises detecting cylinder pressure and estimating cylinder pressure as a function of the detected cylinder pressure.  
     
     
         4 . The method of  claim 3  further comprising providing a cylinder pressure model for estimating the cylinder pressure and providing a cylinder temperature model for estimating cylinder temperature and providing a cylinder fraction model for estimating cylinder fraction.  
     
     
         5 . The method of  claim 4  wherein the emissions control signal is for controlling at least one valve position for controlling an amount of gas flow at a cylinder for controlling cylinder temperature.  
     
     
         6 . The method of  claim 5  wherein the controlling comprises adjusting an EGR valve position for controlling an amount of exhaust gas flow at the cylinder.  
     
     
         7 . The method of  claim 5  wherein the controlling comprises adjusting an exhaust valve position for controlling an amount of exhaust gas flow at the cylinder.  
     
     
         8 . The method of  claim 7  wherein the controlling comprises adjusting an intake valve position for controlling an amount of intake air gas flow at the cylinder.  
     
     
         9 . The method of  claim 5  wherein detecting the engine operating point comprises measuring engine speed and measuring engine load.  
     
     
         10 . The method of  claim 9  further comprising determining an acceptable amount of NO x  based on the engine operating point and estimating an amount of NO x  emissions based on the at least one estimated parameter, wherein the emissions control signal is a function of the acceptable amount of NO x  emissions and the estimated amount of NO x  emissions.  
     
     
         11 . A controller for controlling oxides of nitrogen (NO x ) emissions from a combustion engine, the controller comprising, 
 an estimator configured for estimating at least one parameter from the group of cylinder temperature and cylinder fraction;    a detector configured for detecting an engine operating point and determining at least one desired value for the at least one parameter based on the engine operating point;    a comparator configured for comparing the estimated parameter to the at least one desired value for the at least one parameter; and    a calculator configured for calculating an emissions control signal that increases cylinder temperature when the estimated parameter is below the desired value of the at least one parameter, and that decreases cylinder temperature when the estimated parameter is above the desired value of the at least one parameter.    
     
     
         12 . The controller of  claim 11  wherein the estimator is further configured for estimating the at least one parameter as a function of cylinder pressure.  
     
     
         13 . The controller of  claim 12  wherein the estimator is configured for further estimating cylinder pressure as the function comprising detecting cylinder pressure and estimating cylinder pressure as a function of the detected cylinder pressure.  
     
     
         14 . The controller of  claim 13  wherein the estimator further comprises a cylinder pressure model for estimating the cylinder pressure, a cylinder temperature model for estimating cylinder temperature, and a cylinder fraction model for estimating cylinder fraction.  
     
     
         15 . The controller of  claim 14  further comprising an emissions control signal transmitter configured for adjusting the emissions control signal for controlling at least one valve position for controlling an amount of gas flow at a cylinder for controlling cylinder temperature.  
     
     
         16 . The controller of  claim 15  wherein the emissions control signal transmitter is further configured for adjusting the emissions control signal for controlling an EGR valve position for controlling an amount of exhaust gas flow at the cylinder.  
     
     
         17 . The controller of  claim 15  wherein the emissions control signal transmitter is further configured for adjusting the emissions control signal for controlling an exhaust valve position for controlling an amount of exhaust gas flow at the cylinder.  
     
     
         18 . The controller of  claim 17  wherein the emissions control signal transmitter is further configured for adjusting the emissions control signal for controlling an intake valve position for controlling an amount of intake air gas flow at the cylinder.  
     
     
         19 . The controller of  claim 15  wherein the detector is further configured for detecting the engine operating point based on measuring engine speed and measuring engine load.  
     
     
         20 . The controller of  claim 19  wherein the calculator is further configured for determining an acceptable amount of NO x  based on the engine operating point and estimating an amount of NO x  emissions based on the at least one estimated parameter, wherein the emissions control signal is a function of the acceptable amount of NO x  emissions and the estimated amount of NO x  emissions.