Abstract: Different types of automotive vehicles having differing age and mileage parameters are automatically inspected. The different types of vehicles are variables such as vehicle maker, model, and engine type. A programmed digital computer responds to outputs of measuring instruments for inspected engine, steering and braking responses of the vehicles. For each vehicle, the computer is supplied with data indicative of the vehicle type, the parameters and with signals indicative of the vehicle engine, steering, and braking responses. The computer responds to the program, signals and data to (a) derive extreme values for a range of acceptable values for each of the inspected engine, steering and braking responses, (b) compare the outputs of the measuring instruments indicative of the vehicle engine, steering, and braking responses, and (c) derive a malfunction signal for each engine, steering and braking response outside of the range of values therefor.

Abstract: A combustion knock detection signal for retarding the ignition timing of the internal combustion engine is disabled upon detection of an unstable condition of the storage battery voltage level. Switching means is provided which is operative in response to the unstable condition of the voltage level of the storage battery to disable the knock detection signal, thereby eliminating the production of a false knock detection signal during the engine cranking operation or a certain period after the starting of the engine in which the engine speed is lower than a predetermined level.

Abstract: A plasma jet ignition system for an internal combustion engine has a plasma jet spark plug which receives ignition energy from two energy sources, one for a spark ignition and the other for a plasma jet ignition, and performs a plasma jet ignition as well as a spark ignition. There are further provided various control circuits to control the ignition energy to reduce energy consumption and to promote the functions of the plasma jet ignition. One of these circuits is arranged to stop the plasma jet ignition during a cranking period while cranking is continued after duration of a plasma jet ignition for a predetermined time period. Another control circuit is arranged to control the plasma jet ignition energy corresponding to the engine temperature.

Abstract: A knocking sensor output signal of an ignition advance angle controlling device is subdivided in synchronism with the engine rotation into a knocking portion and a background portion. Both signal portions are rectified and averaged and the averaged portions are compared to derive a difference signal. The ignition advance angle is controlled to advance or to retard in response to said difference signal so as to obtain an optimum control of the advance angle in response to the amount of knocking.

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 fuel injection system equipped with a fuel increase command signal generator for an automotive internal combustion engine, comprising an airflow meter for measuring the airflow rate of the intake air for determining the pulse width of a pulse signal with which fuel injection valves are energized; and a fuel increase command signal generator for producing a command signal with which the fuel flow rate is momentarily increased. The fuel increase command signal generator includes a differentiator and a comparator for detecting the rate of decrease of the airflow, another comparator for detecting the opening degree of the throttle valve of the engine, and an AND gate for producing the fuel increase command signal so that the fuel flow rate is increased only when the rate of decrease of the airflow is over a predetermined value while the throttle valve is closed or nearly closed.

Abstract: A control means is provided in an electronic closed loop air-fuel ratio control system for use with an internal combustion engine, which means controls a time constant of an integrator or a proportional constant of a proportional element of the system so as to optimally control the air-fuel ratio.

Abstract: At least one engine parameter is used to estimate the state of the gas sensor while the frequency of the feedback control signal produced in the closed loop control system is measured to see if it is normal or not. A logic circuit produces a pair of signals respectively indicative of normal or abnormal functioning of the closed loop control system in response to the estimated state of the gas sensor and the frequency of the feedback control signal, to illuminate visual indicators. An additional gas sensor tester is additionally provided for detecting the internal resistance of the sensor.

Abstract: A flow rate detector of the type comprising a corona discharge circuit to cause partial ionization of a fluid at a section of a fluid passage and a probe positioned downstream for detecting the amount of ions carried by the fluid as an indication of the fluid flow velocity. To achieve direct detection of mass flow rate even when the fluid exhibits fluctuation in its density, the detector includes a control circuit which serves the function of maintaining the intensity of a discharge current flowing through the corona discharge circuit constant.

Abstract: A closed-loop emission control apparatus for a multi-cylinder internal combustion engine having a plurality of exhaust systems includes an exhaust composition sensor for each exhaust system and a failure detector responsive to the output from each exhaust composition sensor. The air-fuel ratios of the exhaust systems are controlled by a signal whose amplitude is representative of a mean value of the concentration values of the exhaust composition sensed by both working sensors, and in response to the output from the failure detector the ratios are controlled by a valid signal from a working sensor should the other fail.

Abstract: A control circuit for power steering units of automotive vehicles comprises a wheel speed sensor generating an electrical signal representative of the wheel speed and an RC timing circuit for charging the signal and discharging the stored electrical signal in response to rapid changes in wheel speed. The voltage developed in the RC circuit is coupled to an amplifier through a field-effect transistor to generate an energization current that drives a control valve which in turn regulates the pressure of the working fluid to the power steering unit.

Abstract: Circuit testing apparatus includes a pulse oscillator providing clock pulses, a binary counter for counting the clock pulses to successively generate binary numbers, and a translator which translates the successive binary numbers into a series of test patterns. The test patterns include a series of input bit patterns used to energize the input leads of an electronic logic circuit under test and a series of output binary digits, each of which corresponds to the respective one of the input patterns. Each of the binary digits is compared with an output from the logic circuit under test. When the circuit tested is not functioning as prescribed for a particular set of input pattern, a noncoincidence signal will be produced to disable the binary counter in order to permit the test operator to register the test mode in which the trouble occurred. The binary counter may be enabled manually after registration to complete the prescribed number of tests.

Abstract: An unbraked condition sensor is incorporated in an automatic anti-skid braking system for use with a wheeled vehicle. The unbraked condition sensor comprising a timer, a comparator and an AND gate senses an unbraked condition and functions in such a manner that the AND gate produces a brake re-application output signal for reapplying braking force to the vehicle wheels in response to both a time-delayed output signal which is produced from the timer after a given time delay and a wheel deceleration output signal which is produced from the comparator when the wheel acceleration does not exceed a predetermined threshold value after releasing of the braking force. The predetermined time delay is adjustable.