Engelhard Corporation

Kenneth R Burns

Ronald Marshall Heck

Jack J Early

John T Rubbo

John J Early

A method for controlling the air-to-fuel ratio fed to an engine or other combustion device provides for periodically adjusting the air-to-fuel ratio to stoichiometric or near stoichiometric, within the response range of the conventional exhaust gas sensor employed. This establishes a reference point from which the setting of an air-to-fuel ratio proportioning device (e.g., carburetor) is established by moving its adjustment means a selected distance from its setting at the reference point. The selected value may be outside the normal response range of the sensor, either rich or lean of stoichiometric. The apparatus may include a sensor which generates an output signal which is compared against a reference signal by a comparator. When the output signal exceeds (or falls below) the reference signal, a timer to operate the proportioning device adjustment means in the desired direction for a stated interval of time is actuated. A separate timer operates the adjustment means towards stoichiometric at selected intervals to periodically establish the reference point.

Method and means for controlling air-to-fuel ratio

A system for the control of the air-fuel ratio in an internal combustion engine incorporates an electronic control unit, a sensor of exhaust emissions and a valve for metering fuel with air to control the air-fuel ratio. The electronic control unit provides for the comparison of successive measurements of the sensor output voltage under conditions wherein the fuel valve is being operated for ever increasing richness or leaness until such time as the differential measurement drops below a predetermined amount. An offset voltage is then subtracted from or added to this voltage to calculate an operating set point voltage. Thereby, the system's accuracy is maintained through the compensation for changed sensor characteristics with aging.

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Westfield, NJ, United States of America

Kenneth R Burns