Patent Number: 6,253,541

Title: Triple oxygen sensor arrangement

Abstract: An exhaust system is provided including two catalysts and three oxygen sensors. The second catalyst is disposed downstream of the first catalyst. The first oxygen sensor is disposed upstream of the first catalyst, the second oxygen sensor is disposed downstream of the first catalyst and upstream of the second catalyst, and the third oxygen sensor is disposed downstream of the second catalyst. A goal voltage corresponding to a desired level of nitrous oxide and hydrocarbon within the exhaust is provided for the third oxygen sensor. This goal voltage is based on engine RPM and MAP. The engine controller compares the goal voltage to an actual voltage generated by sensing the level of oxygen downstream of the second catalyst. Based on this comparison, an error value between the goal voltage and the actual voltage is obtained. This error value is converted into a goal voltage for the first oxygen sensor. An actual voltage generated by the first oxygen sensor sensing the amount of oxygen upstream of the first catalyst is compared to the goal voltage derived from the third oxygen sensor. The difference between the goal voltage and actual voltage is used to modulate the pulse width of a signal sent to the fuel injectors of an engine such that the amount of fuel delivered by the fuel injectors is modified. The second oxygen sensor generates an actual voltage corresponding to the amount of oxygen the second oxygen sensor senses downstream of the first catalyst and upstream of the second catalyst. Changes in the actual voltage generated by the second oxygen sensor are compared to changes in the actual voltage generated by the first oxygen sensor. By monitoring the nature of theses changes as they relate to one another, the performance of the first catalyst can be determined.

Inventors: Sullivan; Raymond J. (Royal Oak, MI), Teague; Bruce H. (Grosse Pointe Park, MI), DeGroot; Kenneth P. (Macomb Twp., MI), Reale; Michael J. (Royal Oak, MI)

Assignee: DaimlerChrysler Corporation

International Classification: F01N 11/00 (20060101); F02D 41/14 (20060101); F01N 7/00 (20060101); F01N 7/02 (20060101); F01N 003/00 ()

Expiration Date: 07/03/2018