Method for operating an exhaust valve for diesel particulate filter regeneration

Abstract

A method of operating an exhaust valve ( 28 ) to heat a diesel oxidation catalyst ( 23 ) and to initiate regeneration of a DPF ( 24 ) includes the steps of determining whether the DPF is being cleaned, and determining the speed and quantity of fuel injected into the engine. The method also includes determining an engine back-pressure set point based on whether the engine 14 is fueling. If fueling, the set point is based on the quantity of fuel and the engine speed. If not fueling, the set point is based on whether there is an other request for actuation of the exhaust valve ( 28 ). An exhaust valve set point is determined based on the engine back pressure set point and a current engine back pressure. The exhaust valve ( 28 ) is actuated in response to the exhaust valve set point to obstruct the flow of exhaust gas, where the exhaust gas is heated and initiates regeneration of the DPF ( 24 ).

1 ) A method of operating an exhaust valve to heat a diesel oxidation catalyst and initiate regeneration of a diesel particulate filter on an exhaust aftertreatment system associated with an engine, the method comprising the steps of:
 determining whether the diesel particulate filter is being cleaned;   determining the speed of the engine;   determining the quantity of fuel injected to the engine;   determining an engine back pressure set point based on whether the engine is fueling, wherein when the engine is fueling, the engine back pressure set point is based on the quantity of fuel and the speed of the engine, and wherein when the engine is not fueling, the engine back pressure set point is based on whether there is an other request for actuation of the exhaust valve;   determining a current engine back pressure;   determining an exhaust valve set point based on the engine back pressure set point and the current engine back pressure; and   actuating the exhaust valve in response to the exhaust valve set point to at least partially obstruct the flow of exhaust gas through a fluid passageway of the exhaust aftertreatment system, wherein the exhaust gas is heated in the fluid passageway and initiates regeneration of the diesel particulate filter.   
     
     
         2 ) The method of  claim 1  wherein when there is no other request, the back pressure set point is determined by a braking torque of the engine and the speed of the engine, and when there is an other request, the back pressure set point is determined by the other request. 
     
     
         3 ) The method of  claim 1  wherein the step of determining whether the diesel particulate filter is being cleaned is based on output from a sensor that senses at least one of a backpressure in the aftertreatment system and a temperature in the aftertreatment system. 
     
     
         4 ) The method of  claim 1  further comprising the steps of determining the acceleration of the engine, wherein when the acceleration is greater than zero, the quantity of fuel is determined. 
     
     
         5 ) The method of  claim 1  further comprising the steps of determining the acceleration of the engine, and subsequently determining whether there is the other request for the exhaust valve when the acceleration is not greater than zero. 
     
     
         6 ) The method of  claim 1  further comprising the step of determining a correction value to the engine back pressure set point based on the ambient pressure and temperature. 
     
     
         7 ) The method of  claim 6  further comprising the steps of determining a difference between the correction value and the current engine back pressure, and setting the exhaust valve set point based on the difference. 
     
     
         8 ) The method of  claim 7  further comprising the steps of determining a calculated factor of the engine, and determining a proportional gain using the difference and the calculated factor. 
     
     
         9 ) The method of  claim 8  further comprising the step of setting the exhaust valve set point based on the proportional gain. 
     
     
         10 ) The method of  claim 8  further comprising the step of determining an integral gain using the difference; and setting the exhaust valve set point based on the integral gain. 
     
     
         11 ) The method of  claim 10  further comprises taking an integration of the difference to determine the integral gain. 
     
     
         12 ) The method of  claim 1  further comprising the steps of determining an open loop control value using the engine speed, and determining the exhaust value set point based on the open loop control value.