Fuji Jukogyo Kabushiki Kaisha

Nissan Motor Company Limited

Makoto Shikata

Masaaki Ohgami

Hiroyuki Nakamura

Kazuo Hara

Fujio Matsui

Takuro Morozumi

Hisashi Osano

Yoshiaki Ohara

A system for controlling air-fuel ratio for a carburetor for an internal combustion engine having an induction passage, a throttle valve, an exhaust passage, an exhaust gas detector such as oxygen sensor for detecting the concentration of oxygen in the exhaust gases, air-fuel mixture supply means, an on-off electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply means and an electronic controller. The electronic controller comprises a comparing circuit for comparing the output signal of the detector with a stoichiometric reference, an integration circuit connected to the comparing circuit, a triangular wave pulse generator, and a driving circuit for producing square wave pulses for driving the on-off electromagnetic valve means from the output signal of the integration circuit and of the triangular wave pulse generator for controlling the air-fuel ratio to a value approximately equal to the stoichiometric air-fuel ratio. A constant signal generating circuit is selectively connected operatively to the electronic controller. An idling operation detector produces a signal during idling operation. A switching unit operatively connects the contant signal generating circuit to the electronic controller and renders the electronic control means non-responsive to the output of the exhaust gas detector. The switching unit is adapted to be operated only after a predetermined time delay when the duty ratio of the square wave pulses reaches the maximum or minimum value during the idling operation.

Air-fuel ratio control system

A system for regulating the engine speed so as to maintain the voltage between terminals of a battery at a constant value. A constant-voltage circuit is connected at a terminal of the battery for supplying a constant voltage. A comparator is provided for comparing the voltage between the terminals of the battery with the constant voltage and for producing an output signal in dependency on the difference between the input voltages thereto. The output signal is fed to an actuator through a driving circuit. The actuator operates in response to the driving signal from the driving circuit for opening or closing the throttle valve for regulating the engine speed, so that the voltage between the terminals of the battery may be maintained at a constant level.

System for regulating the engine speed

A system for controlling cooling water temperature for a water-cooled engine has an intake passage, a radiator, a water jacket provided in the engine for cooling the engine, a water passage for communicating the water jacket with the radiator, a thermostat provided in the water passage, the thermostat being so arranged as to open the water passage when the water temperature exceeds a predetermined value, and a pump causing the cooling water in the water jacket to flow. There is provided a bypass connected between the outlet of the water jacket and the inlet of the pump, and a circulation pipe connected between the outlet and inlet of the pump. A solenoid valve is provided for selectively connecting the water passage and circulation pipe with the inlet of the pump and a flow control valve is provided in the water passage for controlling flow rate of water. The solenoid valve operates, when water temperature is higher than a predetermined value, so that the bypass is communicated with the inlet of the pump thereby to cause the water in the water jacket to flow passing through the bypass. The flow control valve is operated in dependency on the engine speed and the load on the engine for the controlling the water temperature at a water temperature higher than the above mentioned predetermined value.

System for controlling cooling water temperature for a water-cooled

A system for regulating the engine speed of an internal combustion engine having a carburetor and a throttle valve in the carburetor. The system comprises an electro-mechanical actuator having an electric motor and a push rod engaged with a throttle lever for maintaining the throttle valve to an open state, a speed sensor for detecting the speed of the engine, and an electronic control circuit. A detecting means is provided for producing a pulse train according to the number of the rotations of the electric motor. The electronic control circuit comprises a comparing circuit connected to the speed sensor, a level setting circuit for applying a standard level to the comparing circuit for comparing the output of the speed sensor with the standard level, a counter for counting the output of the detecting means, and a control circuit for producing a pair of output signals in dependency on the outputs of the comparing circuit and of the counter. Output signals of the control circuit are applied to a driving circuit for driving the electric motor for projecting or retracting the push rod, so that the throttle valve is opened or closed in dependency on the output signals of the speed sensor for controlling the engine speed to the standard level.

A system for controlling air-fuel ratio for an internal combustion engine having a two-barrel carburetor. An electronic controller compares the output signal of an O.sub.2 sensor with a reference corresponding to stoichiometry and for operating on-off electromagnetic valve(s) for controlling the air-fuel ratio to a value approximately equal to the stoichiometric air-fuel ratio. A constant signal generating circuit is selectively connected to the electronic controller. An engine operation detector is provided for detecting the transition from a heavy load condition to light load condition for producing a signal. A switching circuit operatively connects the constant signal generating circuit to the electronic controller for providing a fixed duty ratio of the valve, and renders the electronic controller non-responsive to the output of the O.sub.2 sensor. A switch actuating circuit is provided to actuate the switch by the output signal of the engine operation detector for a predetermined period. Thus, the on-off electromagnetic valve is operated at a small duty ratio after the heavy load condition for a predetermined period.

A system for regulating the engine speed of an internal combustion engine having a carburetor and a throttle valve in the carburetor. The system comprises an electro-mechanical actuator having a push rod engaged with a throttle lever for maintaining the throttle valve to an open state, a speed sensor for detecting the speed of engine, and an electronic control circuit. The electronic control circuit comprises a comparing circuit connected to the speed sensor, a level setting circuit for applying a standard level to the comparing circuit for comparing the output of the speed sensor with the standard level, and a control circuit for producing a pair of output signals for a time period in dependency on the output of the comparing circuit. Output signals of the control circuit are applied to a driving circuit for driving the electro-mechanical actuator for projecting or retracting the push rod, so that throttle valve is opened or closed in dependency on the output signals of the speed sensor for controlling the engine speed to the standard level.

A system for controlling air-fuel ratio for a carburetor for an internal combustion engine having an intake passage, on air-fuel mixture supply device, a throttle valve, an exhaust passage, a detector such as an oxygen sensor for detecting the concentration of oxygen in the exhaust gases, an on-off type electromagnetic valve for correcting the air-fuel mixture and an electronic controller. The electronic controller comprises a comparing circuit for comparing the output signal of the detector with a reference, a proportional and integration circuit for producing a control signal connected to the comparing circuit, a triangular wave pulse generator, and a driving circuit for producing square wave pulses for driving the on-off type electromagnetic valve from the control signals of the proportional and integration circuit and of the triangular wave pulse, generator for controlling the air-fuel ratio to a valve approximately equal to the stoichiometric air-fuel ratio. A holding circuit for memorizing a voltage corresponding to the control signal during an idling operation connectable to the electronic controller. The holding circuit comprises a capacitor for, being charged with the voltage corresponding to control signal and an operational amplifier operated by the voltage charged in the capacitor. A first switch for connecting the capacitor to the electric controller, for charging the capacitor, a second switch for operative connection and disconnection, respectively, of the detector from the electronic controller circuit, and a third switch for connecting during a rapid deceleration that could cause misfiring the output of the amplifier to the electronic controller are provided.

System for controlling air-fuel ratio

A system for controlling the air-fuel ratio for an internal combustion engine having a detector for detecting the concentration of a constituent of exhaust gases passing through the exhaust passage, air-fuel mixture supply device for supplying an air fuel mixture to the induction passage, electromagnetic valves for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply device, a comparator for comparing the output signal of the detector with respect to a predetermined value, an integrating circuit having a proportional circuit for integrating the output of the comparator, a driving circuit for driving the electromagnetic valves in dependency upon the output signal of the integrating circuit. The system has a throttle valve switch actuated by the operation of the throttle valve in an idling condition, steady state and full load condition of the engine and a vacuum switch actuated by vacuum pressure in the induction passage of the engine when the throttle valve is opened to a predetermined degree. A switching circuit is provided to change the proportional constant and integrating constant of the integrating circuit and a decision circuit is provided to actuate the switching circuit in dependency on signals from the throttle valve switch and the vacuum switch, whereby the proportional constant and integrating constant may be changed according to the engine operation.

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Musashimurayama, Japan

Makoto Shikata