Gm Global Technolgoy Operations, Inc.

Guojun Shi

Sharanjit Singh

Minghui Kao

David W Dempsey

James R Yurgil

Randall L Gallagher

David N Benton

An on-board catalyst diagnostic for monitoring the conversion efficiencies of a catalytic converter by measuring the oxygen storage capacity (OSC) of the converter. The measurement of the OSC indicates the degree of health of the converter. Under the same engine running conditions, the greater the OSC measurement, the healthier the converter. A modeled OSC is compared to the real OSC to determine a normalized OSC. The normalized OSC is compared to a predetermined threshold value in order to determine the health of the converter. The modeled OSC takes into consideration variables which will affect the value of the OSC.

Method and apparatus for determining oxygen storage capacity time of a catalytic converter

A method of initializing the catalyst converter for monitoring the conversion efficiencies of a catalytic converter by measuring the oxygen storage capacity (OSC) of the converter. The measurement of the OSC indicates the degree of health of the converter. Under the same engine running conditions, the greater the OSC measurement, the healthier the converter. The catalyst needs to be set to either a rich state or a lean state prior to the measurement of its OSC time. This process is called catalyst state initialization. The catalyst has to be fully saturated from test to test in order to make consistent OSC measurements. This is through open loop fuel control by commanding a lean air to fuel ratio and then monitoring thepost-O2 sensor voltage until it falls below a calibrated value (e.g. 80 mV) indicating a lean state. The system continues to command a lean air to fuel ratio (e.g. 6%) for a calibrated duration of time (e.g. 3 seconds) to saturate the catalytic converter and drive it to a fixed saturation state. This ensures consistent OSC measurement in the second stage of the test.

Methodology of robust initialization of catalyst for consistent oxygen storage capacity measurement

A method for monitoring engine coolant warm-up behavior utilizing a model-based algorithm which provides a moving threshold for accumulated air or accumulated fuel entering into the engine. The algorithm allows for coolant temperature monitoring under a wide range of transient and steady state driving conditions while maintaining safeguards that prevent a false detection. The accumulated air (or fuel) delivered to the engine during the warm-up interval is used to represent the total heat generated by the engine during the warm-up interval. A time-varying moving calculated accumulated air threshold is therefore defined which can deliver accurate pass-fail decisions in conjunction with a predetermined target temperature.

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Wixom, MI, United States of America

Guojun Shi