Nissan Motor Company Limited

Mituhiko Ezoe

Akio Hosaka

Masaharu Asano

Takeshi Fujishiro

Shigeo Aono

Nobuzi Manaka

A circuit is provided in an electronic closed loop air-fuel ratio control system for starting and terminating the operation of the system at different voltages from an exhaust gas sensor.

Electronic closed loop air-fuel ratio control system for use with

Emission control apparatus for internal combustion engines is provided with a sensor for detecting the concentration of a particular exhaust composition in the emissions from the engine. A signal indicating the deviation of the mixture ratio from a controlled point is generated by comparing the output from the sensor with a reference level, the signal being modified in amplitude according to a predetermined control characteristic and used to regulate the air-fuel mixture ratio at the desired control point. The varying magnitude of the sensed concentration is smoothed into a signal of slowly varying magnitude which is used to control the reference level so that error introduced into the deviation indicating signal due to the change with time in the output performance of the exhaust composition sensor is self-compensated. A level sensor is provided to detect when the reference level reaches an end of the control range to change the operating mode of the engine from closed-loop to open-loop mode.

Feedback emission control for internal combustion engines with variable

A reference voltage, which is compared with an output voltage of an exhaust gas sensor in a differential signal generator of an electronic closed loop air-fuel ratio control system, changes depending upon a mean value of an output of the exhaust gas sensor provided in an exhaust pipe extending from an internal combustion engine. Furthermore, the magnitude of the reference voltage is limited in such a manner as to be within a predetermined range, or in other words, the magnitude of the reference voltage is limited at at least one of an upper and a lower values thereof.

Growing community of inventors

Yokosuka, Japan

Mituhiko Ezoe