Patent Number: 6,167,698

Title: Exhaust gas purification system for a lean burn engine

Abstract: An exhaust gas purification system for an engine equipped with a turbocharger and an exhaust pipe having a NO.sub.x conversion catalyst therein. The system comprises a reservoir for storing pressurized air received from the turbocharger, a reductant injector in fluid communication with a reductant supply, and a mixing chamber in fluid communication with the reservoir and connected to the reductant injector. The reductant injector is responsive to an injection signal for atomizing and injecting a quantity of reductant into the mixing chamber. The mixing chamber is in fluid communication with the exhaust pipe for introducing a quantity of air and reductant mixture into the exhaust gas flow upstream of the NO.sub.x conversion catalyst. In one aspect of the invention, the system includes an engine control unit, a valve connected between the reservoir and the mixing chamber, and a differential pressure transducer positioned between the mixing chamber and the exhaust pipe for measuring the pressure differential across the mixing chamber and exhaust pipe upstream of the NO.sub.x conversion catalyst. The engine control unit controls the valve to introduce a quantity of pressurized air from the reservoir into the mixing chamber to maintain the pressure differential between the mixing chamber and exhaust pipe substantially constant.

Inventors: King; Edward Thomas (Dearborn, MI), Vanderslice; John (Berkley, MI)

Assignee: Ford Motor Company

International Classification: B01D 53/94 (20060101); F01N 3/20 (20060101); F02B 37/12 (20060101); F02B 37/16 (20060101); F01N 003/00 ()

Expiration Date: 01/02/2018