Patent ID: 8434299

Claim:
A diesel engine comprising: an exhaust system comprising a diesel particulate filter that treats exhaust gas from the engine; an exhaust back-pressure control device for increasing exhaust back-pressure on the engine sufficiently to cause elevation of the temperature of exhaust gas entering and passing through the diesel particulate filter to a temperature sufficient to initiate combustion of soot trapped by the diesel particulate filter; and a control system for selectively forcing combustion of soot trapped in the diesel particulate filter, wherein the control system comprises a processor that with the engine running a) repeatedly processes data indicative of exhaust gas temperature, data indicative of pressure drop across the diesel particulate filter, data indicative of mass flow through the engine, and data correlating various combinations of pressure drop and mass flow with conditions distinguishing between mandating forced combustion of trapped soot, permitting forced combustion of trapped soot, and not forcing combustion of trapped soot, and b) when a result of the processing discloses a condition mandating forced combustion of trapped soot, the control system operates the exhaust back-pressure control device, regardless of exhaust gas temperature, to increase exhaust back-pressure on the engine sufficiently to cause elevation of the temperature of exhaust gas entering and passing through the diesel particulate filter to a temperature sufficient to initiate combustion of trapped soot, and c) when a result of the processing discloses a condition permitting forced combustion of trapped soot, the control system operates the exhaust back-pressure control device, provided that exhaust gas temperature exceeds a defined temperature threshold, to increase exhaust back-pressure on the engine sufficiently to cause elevation of the temperature of exhaust gas entering and passing through the diesel particulate filter to a temperature sufficient to initiate combustion of trapped soot, in which after the processing has disclosed a condition permitting forced combustion of trapped soot and that exhaust gas temperature exceeds the threshold, the processor processes data that correlates various combinations of engine speed data and engine load data with various degrees of operation of the exhaust back-pressure control device to yield data defining a certain degree to which the device should be operated, and then the control system operates the device to that certain degree.