초록 ▼

An electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit has an open loop calibration for regulating air/fuel ratio that is corrected with a closed loop signal developed by an integral controller. The integral controller

An electronic control unit for regulating the air/fuel ratio of an internal combustion engine is disclosed. The electronic control unit has an open loop calibration for regulating air/fuel ratio that is corrected with a closed loop signal developed by an integral controller. The integral controller bases the closed loop correction signal on a signal from an exhaust gas composition sensor located in the engine exhaust manifold. Various conditions of the system are sensed by a closed loop sensor condition detector to provide information on whether the sensor is up to operating temperature and is operative. If the exhaust gas sensor is functioning and the operating system parameters indicate the system operation should move to closed loop control, the loop is closed by the condition detector. Included in the condition detector circuit is a timer whose cycle is RPM dependent. The timer will time out if the sensor has not indicated an operational capability in one timing cycle or a set number of RPM counts and will generate a signal indicating a sensor failure. After closing the loop, the detector circuit will check for a sensor transition on a periodic basis related to the authority of the integral controller and provide a signal to open the closed loop if the transition does not occur. A rich burst generator is provided to perturbate the loop periodically to produce a rich transition of the sensor if it is operable. A latching failure indicator circuit is additionally included in the system to energize a visual indicator and alert an operator if the failure condition occurs.

대표청구항 ▼

An electronic control unit for the management of the air/fuel ratio of an internal combustion engine; said electronic control unit comprising: open loop calibration means for regulating the air/fuel ratio of the engine in response to sensed engine operating parameters, said open loop calibaration me

An electronic control unit for the management of the air/fuel ratio of an internal combustion engine; said electronic control unit comprising: open loop calibration means for regulating the air/fuel ratio of the engine in response to sensed engine operating parameters, said open loop calibaration means regulating the air/fuel ratio by applying the sensed parameters to a schedule representative of the desired air/fuel ratio and generating an air/fuel ratio control signal therefrom; closed loop calibration means for correcting said open loop calibration with a correction signal in response to the constituent composition of the exhaust gas of said internal combustion engine, said closed loop calibration means including an exhaust gas sensor for providing a bilevel voltage output where one voltage level indicates a rich air/fuel ratio and the other voltage level indicates a lean air/fuel ratio; and a failure indication means for sensing the failure of operation of the exhaust gas sensor and for providing a failure condition signal; said operational failure of the exhaust gas sensor being sensed by the lack of a transition between the output levels of the sensor during a delay time wherein said delay time is varied with at least one operating parameter of the internal combustion engine related to sensor operation.