Abstract: An exhaust gas flow concentration system for a catalyst includes an inlet that receives a flow of exhaust gas from an exhaust pipe of an exhaust system, a stationary tube in communication with the inlet and disposed upstream from the catalyst, and an extension tube in communication with the stationary tube and disposed upstream from the catalyst, where the extension tube includes a cross-sectional area less than a cross-sectional area of the catalyst. A displacement device is coupled to the extension tube and is configured to (i) displace the extension tube relative to the stationary tube downstream towards the catalyst as a temperature in the exhaust system decreases away from a light-off temperature of the catalyst and (ii) retract the extension tube relative to the stationary tube upstream away from the catalyst when the temperature in the exhaust system reaches the light-off temperature of the catalyst.

Abstract: An exhaust gas flow concentration system for a catalyst includes an inlet that receives a flow of exhaust gas from an exhaust pipe of an exhaust system, a stationary tube in communication with the inlet and disposed upstream from the catalyst, and an extension tube in communication with the stationary tube and disposed upstream from the catalyst, where the extension tube includes a cross-sectional area less than a cross-sectional area of the catalyst. A displacement device is coupled to the extension tube and is configured to (i) displace the extension tube relative to the stationary tube downstream towards the catalyst as a temperature in the exhaust system decreases away from a light-off temperature of the catalyst and (ii) retract the extension tube relative to the stationary tube upstream away from the catalyst when the temperature in the exhaust system reaches the light-off temperature of the catalyst.

Abstract: A catalyst degradation detection method for use with a zero ceria catalyst. The method uses techniques to measure transient responses to engine control events of upstream and downstream sensors to determine catalyst degradation and performance. By measuring transient behavior, the method can determine catalyst degradation and performance based on the limited oxygen storage of precious metal catalysts that do not include added ceria or other materials with high oxygen capture rates.

Abstract: A catalyst degradation detection method for use with a zero ceria catalyst. The method uses techniques to measure transient responses to engine control events of upstream and downstream sensors to determine catalyst degradation and performance. By measuring transient behavior, the method can determine catalyst degradation and performance based on the limited oxygen storage of precious metal catalysts that do not include added ceria or other materials with high oxygen capture rates.

Abstract: An air/fuel control system (10) and method for an engine (28) coupled to a catalytic converter (50) includes monitoring of the converter (50). Engine air/fuel ratio is controlled (104-178) in response to a pair of two-state signals generated by comparing the outputs of respective upstream (44, 55) and downstream (52) exhaust gas oxygen sensors to a reference voltage. The transitions in the downstream sensor are indicated when a difference in its output amplitude changes signs and a difference between stored peak values occurring during two successive changes in the sign exceeds a predetermined value (200-350). Converter efficiency is indicated from a ratio of transitions in the downstream sensor transitions to transitions in the upstream sensor output which are generated in a similar manner (690-770).