Patent ID: 7849680

Claim:
A small form factor active/passive diesel particulate filter system for a diesel auxiliary power unit installed on a body having a main diesel engine, comprising: an exhaust pipe connected to an exhaust port of the diesel auxiliary power unit for carrying an exhaust gas including a particulate matter output by the diesel auxiliary power unit, the exhaust pipe having a first internal cross-sectional surface area; a sensor connected to the exhaust pipe for monitoring an exhaust backpressure within the exhaust pipe; a coil assembly connected to the exhaust pipe and having a second internal cross-sectional surface area of less than 150% of the size of the first internal cross-sectional surface area for heating the exhaust gas carried by the exhaust pipe to the coil assembly and actively igniting the particulate matter; a relay switch connected to an AC power generator of the diesel auxiliary power unit and the coil assembly for providing power to the coil assembly; an oxidation catalyst connected to the coil assembly having a third internal cross-sectional surface area approximately equal to the second internal cross-sectional surface area for injecting NO 2 into the exhaust gas passing through the oxidation catalyst to passively ignite the particulate matter after the coil assembly stops actively igniting the particulate matter; a filter assembly connected to the oxidation catalyst having a fourth internal cross-section surface area approximately equal to the third internal cross-sectional surface area for trapping a large percentage of the particulate matter; and an electronic control unit connected to the sensor for receiving a first signal from the sensor representative of the exhaust backpressure within the exhaust pipe and sending a second signal to the relay switch when the first signal represents a regeneration threshold for exhaust backpressure, the second signal causing the relay switch to provide power to the coil assembly from the AC power generator.