Abstract: An air flow rate compensation circuit is provided to compensate for an erroneous air flow rate signal produced in response to the movement of the flap of an air flow meter disposed in the intake air passage of an internal combustion engine where the erroneous nature of the signal occurs because of an overshoot characteristic of the flap. The compensation circuit produces an output signal with which either an air/fuel ratio control signal produced in response to the air flow rate signal or the air flow rate signal per se is modified where the output signal is produced in response to the movement of the throttle valve or the variation of the air flow rate signal.

Abstract: 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.

Abstract: 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.

Abstract: In a closed-loop mixture control system for internal combustion engines, the concentration of an exhaust composition contained in the emissions from the engine is compared with a predetermined value in a comparator to determine whether the fuel quantity is to be corrected in a direction to increase it or decrease it. The rate of change of the correction is controlled in response to a sensed acceleration or deceleration of the engine for a small duration of time to compensate for the error arising from the transport delay time of the engine at the instant of the acceleration or deceleration.

Abstract: 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.

Abstract: Apparatus for controlling air-fuel mixture applied to internal combustion engines comprises an exhaust composition sensor providing an electrical signal representative of the concentration of a composition of the exhaust gases, an integral controller receptive of the electrical signal to generate a correction signal for the air-fuel mixing and proportioning device to control the air-fuel ratio at a desired value. An engine condition sensor is provided to detect transient engine operating conditions to generate a control signal which is used to maintain the output voltage of the integral controller at a predetermined constant value so that the voltage swing during vehicle acceleration or deceleration is held within a minimum range.