Abstract: An air-fuel ratio control system for a carburetor of an internal combustion engine comprises an O.sub.2 -sensor for detecting the concentration of the oxygen constituent of exhaust gases passing through an exhaust passage, an on-off electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the carburetor, an electronic control circuit comprising a comparator for comparing an output signal of the O.sub.2 -sensor, an integration circuit, and a driving circuit for producing driving pulses for driving the electromagnetic valve in dependency on an output signal of the integration circuit for controlling the air-fuel ratio. A detector, such as an ignition pulse generating device, is provided for detecting conditions of operation of the internal combustion engine and for producing an engine operation signal, and a current control circuit responds to the engine operation signal for producing an output current.

Abstract: An infinitely variable transmission has a primary pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, a secondary pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, and a belt engaged with both pulleys. A hydraulic circuit having a transmission ratio control valve is provided for shifting the disc of the primary pulley in the downshift direction and upshift direction. The transmission ratio control valve is operated to shift the disc of the primary pulley in the downshift direction when the throttle valve of the engine is rapidly opened for accelerating the engine.

Abstract: A system for controlling the transmission ratio of an infinitely variable transmission has a primary pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, a secondary pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc and a belt engaged with both pulleys, and a hydraulic circuit. The system further comprises a transmission ratio control valve for controlling the fluid applied to the hydraulic cylinder of the primary pulley and for shifting the disc of the primary pulley, and devices for detecting conditions of engine operation and for producing electrical signals.An electric control unit responds to the electrical signals to produce control signals. A solenoid operated valve is provided to respond to the control signals to control the transmission ratio control valve so as to control the transmission ratio by the pulleys.

Abstract: A system for controlling power transmission of a four-wheel drive vehicle having main driving wheels of the vehicle powered by an engine. A clutch transmits the power of the engine to auxiliary driving wheels of the vehicle so as to provide forward drive. A transmitter transmits a high frequency wave to a surface of a road in front of the vehicle and a receiver receives the reflected wave. A comparator is provided for comparing the received wave with the transmitted wave. When the difference between the amplitudes of both waves exceeds a reference value, a control circuit engages the clutch for the four-wheel drive.

Abstract: An engine speed control system for an internal combustion engine mounted on a vehicle comprises an actuator for actuating a throttle valve for increasing and decreasing the idling speed, an ignition switch for producing a signal during the operation of the engine, an engine speed signal generating circuit, an engine speed increasing signal generating circuit and an engine speed decreasing signal generating circuit, an actuator control circuit for operating the actuator in opposite directions in accordance with engine speed increasing and decreasing signals, a vehicle speed signal generating circuit, and an idling signal generating circuit for generating an idling signal in the idling operation of the engine. A stop switch is provided for producing a signal when the throttle valve reaches the closed position.

Abstract: Speed detectors are provided for detecting speeds of each of the four wheels of a vehicle. An electric circuit is provided to compare the speeds of all wheels and to turn on at least one lamp when a difference between individual wheel speeds is detected, whereby slipping of wheels is indicated.

Abstract: A feedback control system in which the error signal is oscillated by a dither signal having a periodical pattern for oscillating the controlled output. The dither signal comprises a plurality of positive excursions and negative excursions, and at least one of the positive excursions is lower than the others and at least one of the negative excursions is shallower than the others. The dither signal is applied to an actuator to produce a controlled output. A detector senses the value of the controlled output caused by the operation of the actuator. The detector is adapted to produce an output signal in which portions corresponding to at least the low positive excursion or negative excursion of the dither signal are removed when the controlled output deviates from a desired value in different directions.A comparing circuit compares the output signal of the detector with a standard signal value.

Abstract: An air-fuel ratio control system for an internal combustion engine having an emission control system with a three-way catalytic converter for controlling the air-fuel ratio in accordance with the operation of the engine. A throttle sensor for detecting acceleration of the engine and a predetermined voltage supply device are provided. A feedback control circuit is provided for controlling the air-fuel ratio to the stoichiometric air-fuel ratio in a normal operating condition and for stopping the control operation when the acceleration of the engine is detected by the throttle sensor. A first switch is provided to be actuated by the output of the throttle sensor to connect the output of the predetermined voltage supply with the input of the feedback control circuit when acceleration is detected.

Abstract: An engine idling speed control system for an internal combustion engine comprising an actuator for actuating a throttle valve for increasing and decreasing the idling speed, an engine speed signal generating circuit, an engine speed increasing signal generating circuit and an engine speed decreasing signal generating circuit, a vehicle speed detecting circuit for generating a signal when the vehicle speed is lower than a predetermined value, an idling signal generating circuit for generating an idling signal in the idling operation of the engine, an engine speed detecting circuit for producing a signal when the engine speed is higher than a predetermined value, and an actuator control circuit for operating the actuator in opposite directions in accordance with engine speed increasing and decreasing signals.

Abstract: An air-fuel ratio control system for an internal combustion engine having an emission control system with a three-way catalytic converter for controlling the air-fuel ratio in accordance with the operation of the engine. A throttle sensor for detecting a wide-open throttle operation of the engine and a predetermined voltage supply circuit are provided. A feedback control circuit is provided for controlling the air-fuel ratio to the stoichiometric air-fuel ratio in a normal operating condition. A memorizer circuit memorizes a value corresponding to the control output of the feedback control circuit. A first switch means is actuated by the output of the throttle senor to connect the output of the predetermined voltage supply circuit with the input of the feedback control circuit when acceleration is detected, and to cut off the input of the memorizer circuit for maintaining the stored content thereof.

Abstract: An air-fuel ratio control system for an internal combustion engine comprises an induction passage, a carburetor, an on-off type electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied to the carburetor, an O.sub.2 -sensor for detecting oxygen concentration of exhaust gases, and a feedback control circuit responsive to the output of the O.sub.2 -sensor for producing pulses for driving said electromagnetic valve for correcting the air-fuel ratio.An engine speed detecting circuit is provided for producing an output signal which varies with the engine speed; and a frequency changing circuit is provided to be responsive to the output signal of the engine speed detecting for changing the frequency of the pulses whereby the electromagnetic valve may be prevented from resonating with the vibration of the engine and with the pulsations of induced air.

Abstract: A feedback control system in which the error signal is oscillated by a dither signal having a periodical pattern for oscillating the controlled output. The dither signal comprises a plurality of positive excursions and negative excursions, and at least one of the positive excursions is lower than the others and at least one of the negative excursions is shallower than the others. The dither signal is applied to an actuator to produce a controlled output. A detector senses the value of the controlled output caused by the operation of the actuator. The detector is adapted to produce an output signal in which portions corresponding to at least the low positive excursion or negative excursion of the dither signal are removed when the controlled output deviates from a desired value in different directions.A comparing circuit compares the output signal of the detector with a standard signal value. The output signal of the comparing circuit is signal for detecting the removed portions.

Abstract: A system for electronically detecting the transient state of engine operation of an internal combustion engine having a spark ignition system. A measuring circuit counts pulses having the pulse separation of the ignition timing of the spark ignition system and produces data output. A plurality of memorizing circuits are provided for memorizing old data output from the measuring circuit and a subtractor compares the old data output and the memorizing circuit with the new data output from the measuring circuit and produces the difference between the data and the amount of the difference. The output of the subtractor is used for correcting the air-fuel ratio of the air-fuel mixture of an emission control system using a three-way catalytic converter.

Abstract: An instructing system for a four-wheel drive vehicle powered by an internal combustion engine comprises a transmission for transmitting power from the engine to two main driving wheels, a clutch for selectively transmitting the power to auxiliary two-wheels, and a select lever for engaging the clutch. Speed detectors are provided for detecting both the speed of the two main driving wheels and the two auxiliary wheels. An electric circuit compares both speeds and turns on a lamp when the difference between both speeds exceeds a predetermined level, whereby slipping of the two main driving wheels is indicated.

Abstract: An air-fuel ratio control system for an internal combustion engine having an emission control system with a three-way catalytic converter for controlling the air-fuel ratio in accordance with the temperature of the engine and operation of the engine. A temperature sensor for detecting the engine temperature and a negative pressure sensor for detecting the engine manifold vacuum in the induction passage are provided. A feedback control circuit is provided for controlling the air-fuel ratio to the stoichiometric air-fuel ratio in a normal operating condition and for stopping the control operation when the acceleration in the cold engine is detected by the temperature sensor and the negative pressure sensor. A first switch is provided to be actuated by the output of the negative pressure sensor to connect the output of the temperature sensor with the input of the feedback control circuit when the negative pressure is lower than a predetermined value.

Abstract: An air-fuel ratio control system for an internal combustion engine having an intake passage, an exhaust passage, an air-fuel mixture supply, on-off type electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by said air-fuel mixture supply, a dither signal generating circuit for producing a periodical dither signal having a constant wave pattern, a shift control circuit for shifting the level of the center of the dither signal, a driving circuit for producing a driving output according to the dither signal, and an O.sub.2 sensor for detecting the concentration of oxygen in exhaust gases passing through the exhaust passage. The system is provided with a device for detecting a transient state of the engine operation, and a control circuit including an integrating circuit connected to the O.sub.2 sensor and a square wave generating circuit for generating square pulses according to the integration output of the integrating circuit for driving the electromagnetic valve.

Abstract: 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.

Abstract: An air-fuel ratio control system for an internal combustion engine having an intake passage, an exhaust passage, an air-fuel mixture supply device, an on-off type electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply device, a dither signal generating circuit for producing a periodical dither signal, a shift control circuit for shifting the level of the center of the dither signal, a driving circuit for producing a driving output for the on-off type electromagnetic valve, and an O.sub.2 sensor for detecting the concentration of oxygen in exhaust gases passing through the exhaust passage. A timing circuit is provided for detecting the period of the time when the output of the O.sub.2 sensor is higher than a predetermined level and the period of the time when the output is lower than the predetermined level for producing an output signal in dependency on the difference between the periods.

Abstract: An air-fuel ratio control system for an internal combustion engine having an intake passage, an exhaust passage, air-fuel mixture supply unit, on-off type electro-magnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply unit, a dither signal generating circuit for producing a periodical dither signal having a waveform, a shift control circuit for shifting the level of the center of the dither signal, a driving circuit for producing a driving output according to the dither signal, and detecting means for detecting the concentration of oxygen in exhaust gases passing through the exhaust passage. The system is provided with a memory circuit unit for memorizing a peak level of output of the detecting circuit and for producing an output according to the memorized peak level, first circuit being applied with outputs of the detector and of the memory circuit for detecting deviation of the dither signal detected by the detector.

Abstract: A system for controlling the air-fuel ratio for an internal combustion engine having an intake passage, an exhaust passage, a detector such as an oxygen sensor for detecting the concentration of oxygen in the exhaust gases, an air-fuel mixture supply unit, an on-off type electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply unit, and an electronic control circuit for producing square wave pulses in dependency on the output signal from the detector for driving the on-off type electromagnetic valve.