Abstract: In a system for producing a pulse signal for controlling an internal combustion engine, an engine control pulse signal is calculated by a digital computer during normal operation. If a failure or a malfunction of the digital computer is detected, the engine control pulse signal is replaced with a dummy signal produced by an auxiliary pulse generator.

Abstract: A malfunction preventing system for a microcomputer system is disclosed which detects an abnormal condition in the program execution to produce an alarm or reset signal to automatically restart the computer. The malfunction preventing system is applicable to automotive engine control wherein the computer is capable of returning to normal operation upon detecting a malfunction in program operation for fuel parameter calculation, thereby to keep the automotive engine control in order.

Abstract: An automatic control system for an automotive vehicle in use with a microcomputer has a checking system for checking an input unit, a ROM, a RAM and an output unit of the microcomputer. The checking system comprises a means which stores various checking programs to be executed for checking above-mentioned elements of the microcomputer. The checking system effectively operates to check the elements without causing expanding of duration of execution of the checking programs.

Abstract: A fuel injection rate control system for a fuel-injection internal combustion engine, wherein basic fuel injection rate signals are produced upon detection of the load on the engine and the engine output speed and are modified by the correction values read out from a collection of data indicating various correction values in terms of the engine output speed and the engine load. When the correction values selected are zeros or smaller than a predetermined value, the fuel injection rate may be controlled to achieve a predetermined air/fuel ratio in the engine through detection of the air/fuel ratio of the mixture produced in the engine.

Abstract: A fuel supply control system is disclosed which uses a stored program type digital computer for calculating a basic amount of fuel and modifying the basic amount in accordance with various correction factors dependent upon engine operating conditions so as to determine an actual amount of fuel supplied to an engine. The actual fuel amount is determined by adding all correction factors dependent upon engine temperature and multiplying the sum by the basic fuel amount.

Abstract: An air fuel ratio controlling device able to exhaust gas purification efficiently by shortening the time for judgement of starting of the closed loop control by adjusting the current supply in a small extent to be fed to an exhaust gas sensor.

Abstract: A rotatable disk having a plurality of calibration segments and at least one marker along the peripheral portion thereof is provided while a stationary pick-up provided adjacent the disk for generating a first signal indicative of calibration segments and a second signal indicative of a reference position of the rotation of the disk. The frequency of the first signal is increased in order to accurately measure the rotational angle from the reference position.

Abstract: A fuel injection system for an automotive internal combustion engine equipped with a fuel cut off control signal generator comprises a smoothing circuit which smoothes a fuel cut off control signal produced in response to engine parameters. The flow rate of fuel injected via injection valves is controlled in accordance with the pulse width of a valve energization signal where the pulse width thereof is further controlled by the voltage of the fuel cut off control signal so that the fuel flow rate decreases and increases exponentially in the same manner as the voltage of the fuel cut off control signal when the fuel flow is cut off and is reestablished. Two monostable multivibrators and two transistors are provided for selectively transmitting and blocking the fuel cut off control signal so as to prevent misfires of the engine when the fuel flow rate is below a predetermined value.

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: A fuel control system for an internal combustion engine includes an exhaust gas sensor from which feedback control signal is derived, a limiter for limiting the maximum and minimum voltages of the control signal and a triangular wave generator. The triangular wave has a constant amplitude peak of which the maximum value is slightly greater than the maximum voltage of the control signal and the minimum value is slightly below the minimum voltage of the control signal. A comparator is provided to produce an output at one of two binary levels depending upon whether the control signal is above or below the instantaneous value of the triangular wave. The output from the comparator is a train of pulses whose duty cycle ranges from predetermined minimum to maximum values which correspond respectively to the minimum open and closure times of air-fuel mixing control valves.

Abstract: A mixture control system for an internal combustion engine comprising an exhaust gas sensor and a source of time-varying current connected to the gas sensor to inject thereto a current which varies periodically between two constant values to develop a corresponding periodically varying voltage signal which superimposes a voltage signal developed in response to the ratio of mixture supplied to the engine. An amplitude detector is provided to detect the periodically varying voltage signal to develop a signal representative of the temperature of the gas sensor. The detected voltage signal is compared in a comparator with a reference level corresponding to the operating temperature of the gas sensor to operate the mixture control system in open-loop mode, when the gas sensor is operating below the operating temperature.

Abstract: A closed-loop emission control apparatus for internal combustion engines includes an exhaust composition sensor disposed at the upstream side of a catalytic converter which converts the noxious exhaust components into harmless products at the highest efficiency when the air-fuel ratio is controlled at a value in the vicinity of stoichiometry in accordance with a control signal derived from the sensed concentration of the exhaust composition. The output from the exhaust composition sensor is utilized to generate an offset voltage by averaging the instantaneous values of the sensed concentration, the offset voltage being combined with the control signal to cancel an error introduced thereinto during use of the apparatus.

Abstract: A closed loop fuel control system for an internal combustion engine having in its exhaust system an exhaust composition sensor generating a signal indicative of air-fuel ratio in gases in the exhaust system and an integral controller providing integration on the generated signal for adjusting the ratio of air and fuel supplied to the engine, and a storage device which stores the output from the controller in response to a sensed particular engine operating parameter. The stored signal is later extracted in response to the sensing of the same engine operating parameter to rapidly vary the controller output.

Abstract: In a fuel mixture control system including an exhaust gas sensor located within an exhaust system of an internal combustion engine, maximum and minimum peak values of the gas sensor output are detected. A direct-current pedestal is added to the detected minimum peak value. A comparator detects when the added minimum peak exceeds the detected maximum peak value to provide a disabling signal to the mixture control system to switch its operational mode from closed loop control to open loop control when the temperature of the gas sensor falls below its operating temperature typically during prolonged idle condition.

Abstract: A closed loop mixture control system for an internal combustion engine of a motor vehicle is provided with a voltage divider connected across the terminals of a single source of DC potential mounted on the vehicle to develop an offset voltage which is combined with the output of an exhaust gas sensor having a bipolar output characteristic. One of the polarities of the exhaust gas sensor output is compensated for by the offset voltage.

Abstract: A differentiator is provided in an electronic closed loop air-fuel ratio control system to speed up a response of the system and also to precisely control an air-fuel ratio of the air-fuel mixture fed to the engine.

Abstract: A closed-loop emission control system for an internal combustion engine having an exhaust composition sensor includes an averaging circuit for generating a signal representative of the average value of the sensed exhaust composition, and a balanced differential amplifier receptive of the average and instantaneous values of the sensed composition to generate an output indicating the difference therebetween. A DC bias is applied to the differential amplifier to fluctuate the difference signal above and below the DC bias level.

Abstract: A reference signal with which the output of a gas sensor is compared is produced by detecting the maximum and minimum values of the output of the gas sensor and adding via a voltage divider these values to each other. The variation of the reference signal may be limited with predicted maximum and minimum values of the output of the gas sensor. The reference signal produced in such a manner may be utilized for disabling and reactivating the feedback control.

Abstract: The variation range defined between the maximum and the minimum output voltages of a gas sensor in the exhaust passage is detected and compared with a reference signal which can have hysterisis characteristics. Engine operational parameters are utilized to disable and/or reactivate the system as well as the sensed sensor response, while the air-fuel ratio can be arbitrarily varied to test if the sensor is below an effective working temperature and reactivate the system.

Abstract: In a mixture control system having an exhaust gas sensor located in an exhaust system of an internal combustion engine for controlling the air-fuel ratio of the mixture supplied to the engine, a detection system for detecting when the temperature of the exhaust gas sensor is within its normal operating range. A deviation signal is derived from the exhaust gas sensor to represent the deviation of the air-fuel ratio within the exhaust system from a desired air-fuel ratio. The peak value of the deviation signal is detected and stored in a storage circuit and compared with a threshold which represents the normal operating temperature of the exhaust gas sensor to provide a disabling signal for the mixture control system to suspend feedback control operation when the temperature of the sensor falls below its normal operating temperature.