Abstract: A closed-loop mixture control system for an internal combustion engine comprises a throttle position sensor and a compensator connected thereto to provide an error compensating signal in response to a throttle change. The signal is feedforwarded to adjust the air-fuel ratio to the varying engine parameters prior to the generation of control signals.

Abstract: In a closed loop electronic fuel injection control unit having a basic fuel schedule in response to engine operating conditions, the amount of oxygen in the exhaust gases is detected and compared with a desired value to provide an error signal. The error signal is shaped to form a series of binary pulses of alternating voltages of constant amplitude in correspondence with the plus and minus deviation from the reference voltage which represents the desired oxygen quantity. The binary pulses are amplified by a variable gain amplifier to provide a signal which is used to adjust the basic fuel schedule. The time duration of each binary pulse is measured by a counter to provide an output when a pulse width reaches a predetermined interval. The counter output is coupled to the amplifier to increase the amplifier gain to change the rate of fuel supply.

Abstract: The oxygen component of exhaust gases from internal combustion engine is sensed and compared with a reference value which represents the stoichiometric air-fuel ratio of the engine to provide an error signal at one of two discrete values depending on whether the amount of oxygen component is above or below stoichiometry. The error signal is connected to integrating and/or proportional controllers. Operating parameters of the engine are sensed to control the integrating and/or proportional gains of the controllers upon the sensed parameters reaching a predetermined value. The output from the controllers is used to control the air-fuel ratio of the engine.

Abstract: In an electronic closed loop control system for optimally controlling the air-fuel mixture fed to an internal combustion engine, two electrical circuits are provided: one for removing cumbersome manual adjustment of a standard signal level for ensuring the system a proper air-fuel ratio control, and the other for ensuring the system a proper control during a certain period after initially energizing the system.