Importance

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Abstract

An electronic engine controller limits the maximum temperature of a midbed point within a catalytic converter by determining an instantaneous temperature of the midbed point as a function of a temperature of exhaust gas at an exhaust flange, of a temperature variation of exhaust gas from the exhaust flange and exhaust gas inlet to the catalytic converter, of exhaust gas at an exhaust gas inlet to the catalytic converter, and as a function of a predetermined value indicative of a temperature rise of exhaust gas in the catalytic converter. The temperature is compared to a maximum midbed temperature range and a first air/fuel modulation variable is altered by a predetermined amount if the temperature of the midbed point is within the maximum midbed temperature range and the first air/fuel modulation variable is set to a predetermined value if the midbed temperature is below the maximum midbed temperature range. The first air/fuel modulation variable is compared to a second air/fuel modulation variable which corresponds to an air/fuel ratio required to produce a predetermined engine response and the rate of fuel delivery to the engine is altered to generate an air/fuel ratio corresponding to the air/fuel modulation variable which represents the richer air/fuel mixture.

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First Claim