Patent ID: 7434388

Claim:
A method for regenerating a particulate filter by controlling fuel delivery to a oxidation catalyst, the oxidation catalyst and particulate filter being in gaseous communication with a four-stroke internal combustion engine having a number of cylinders for internal combustion which emit exhaust gases, the method comprising: determining an amount of fuel to be included within the exhaust gases such that a desired temperature of said exhaust gases may be achieved out of the oxidation catalyst to facilitate regeneration; emitting fuel from the engine as a function of the determined amount of fuel so as to facilitate regeneration of the particulate filter without requiring use of a fuel injection device downstream of the engine; controlling valve timing in order to control an amount of fuel emitted from the engine to the particulate filter, wherein controlling the valve timing includes controlling opening or closing of at least one of an intake valve or exhaust valve such that a positioning of the at least one controlled valve is not fixed during all four strokes of the four-stroke engine; determining a desired exhaust gas temperature for gases emitted from the engine to facilitate regeneration, and emitting exhaust gases from the engine at the desired exhaust gas temperature by operating the engine with at least one unfueled cylinder; and wherein regeneration of the particulate filter is required when the engine is operating at idle speed, and wherein emitting exhaust gases from the engine at the desired exhaust gas temperature includes operating the engine at an increased idle speed and with at least one unfueled cylinder and one or more cylinders having fuel injected below the auto ignition temperature and pressure.