Patent Number: 6,167,696

Title: Exhaust gas purification system for low emission vehicle

Abstract: An exhaust gas purification system for a lean burn internal combustion engine including a three-way catalyst, a hydrocarbon trap downstream of the three-way catalyst, a NO.sub.x trap downstream of the hydrocarbon trap, and an electrically heated catalyst located between the hydrocarbon trap and NO.sub.x trap. In one embodiment, the NO.sub.x trap includes an integral particulate filter having alternating blocked channels extending longitudinally. The inlet channels filter particulate matter and the outlet channels have a NO.sub.x absorbent wash coat for absorbing exhaust gas NO.sub.x. A method of controlling the exhaust system during cold start engine operation is provided to reduce cold start emissions. The method further includes a control procedure for activating the electrically heated catalyst for desulfation and particulate matter burn-off.

Inventors: Maaseidvaag; Frode (Ann Arbor, MI), Hepburn; Jeffrey Scott (Dearborn, MI)

Assignee: Ford Motor Company

International Classification: F01N 3/08 (20060101); F01N 3/20 (20060101); F01N 7/00 (20060101); F01N 7/02 (20060101); F01N 003/00 ()

Expiration Date: 01/02/2018