Abstract: Disclosed is an azimuth determination apparatus attached to a motor vehicle for determinating the forward direction of the vehicle. The azimuth determination apparatus includes an azimuth sensor for generating orthogonal first and second signals indicative of the forward direction of the vehicle. Two azimuth vectors are obtained on the basis of the orthogonal first and second component signals, first components of the two azimuth vectors being maximum and minimum. The determination is made in terms of the fact that the difference between second components of the two azimuth vectors is below a predetermined value. In accordance with the determination, the orthogonal first and second component signals are corrected on the basis of said two azimuth vectors so that the accurate moving direction of the motor vehicle can be obtained irrespective of the remanence of the vehicle.

Abstract: A system for controlling the operating condition of an engine in which a temperature sensing element constitutes an airflow measuring device disposed in an intake air passage of the engine. The temperature sensing element is supplied with a heating current in response to a start pulse signal produced with every one-half period of each combustion cycle of the engine. A comparator delivers an output signal when a reference temperature set on the basis of the air temperature measured by an auxiliary temperature sensing element is reached by the temperature of the temperature sensing element. A pulse signal indicative of the time interval between the generation of the start pulse signal and a rise in the output signal of the comparator is delivered as an airflow measurement signal.

Abstract: An engine control apparatus for controlling the quantity of fuel injected into the engine is equipped with an intake air flow rate measuring device for detecting the operating state of the engine. This measuring device has a heat sensitive element, which is located in the intake pipe, and outputs a pulse signal having a pulse width T corresponding to the intake fuel amount. Engine control apparatus has a plurality of map memory means in which a plurality of functions f.sub.1 (N), f.sub.2 (N), f.sub.3 (N), which express the polynomial approximation ##EQU1## for expressing the air flow rate G/N per engine revolution, are stored as the parameters of the number of engine rotations N. These functions are read out from the maps and, based on the number of engine rotations N, the fuel injection amount corresponding to the pulse width T of the air flow rate is calculated.

Abstract: A control system for an engine has a temperature sensitive element as part of a device for measuring the air flow in an air intake manifold to the engine. Further, a first pulse signal is generated, corresponding to the rotation of the engine, for controlling the setting of a flip-flop. A transistor is conducted in the set state of the flip-flop to supply a heating electric current to the element. The element supplied with the current is raised to the temperature that corresponds to the air flow in the manifold. When the temperature of the element is raised until the specified temperature difference to the air temperature (measured by a sub temperature sensitive element) is set, the temperature difference is detected by a comparator, and the flip-flop is reset by the detection signal.

Abstract: In an apparatus for controlling an engine, as an air flow sensor for measuring intake air flow quantity, a heater resistor having temperature-resistance characteristic and a temperature sensitive resistor for sensing air temperature are provided in an intake passage, and heating electric power is supplied to the heater resistor in response to a start signal generated periodically. The heating electric power is cut off when the temperature of the heater resistor is raised to a specified reference temperature predetermined in accordance with the air temperature, so that an output signal indicative of the time width in which the heating electric power is supplied is applied to an electronic control unit to measure air flow quantity therefrom.

Abstract: A heater, which comprises an element whose resistance varies with changes in temperature, and a temperature element are provided in the air intake pipe of an engine. This heater and temperature element together with resistors form a bridge circuit to which heating power is supplied via a transistor. An engine control unit generates start signals Tin simultaneously with the rotation of the engine. A flip-flop circuit is set by these start signals and, when set, the transistor is turned on and the heating power rises. The output signal from the bridge circuit is supplied to a comparator and the output signal of the comparator resets the flip-flop circuit, which outputs a pulse-shaped signal representing the airflow quantity as a length of time. This pulse-shaped time signal is sent via a constant current circuit to another comparator, where it is compared with a reference voltage and the output signal from the comparator is supplied together with the above time signal to an exclusive OR circuit.

Abstract: An engine control apparatus has an air flow rate measuring device for measuring an intake air flow rate. A temperature sensing element having a temperature characteristic and constituting the device is arranged in an intake pipe. The device generates an output pulse signal having a pulse width T corresponding to the intake air flow rate. An engine control unit has the one-dimensional map for storing the relationship between the engine speed N and the pulse width to of the signal corresponding to the air flow rate. This data to is read out from the one-dimensional map in accordance with the engine speed N. Subsequently, the data to is subtracted from the data T to calculate a time duration t. The unit also has a two-dimensional map for storing the relationship between each time duration t and the corresponding rate G/N in correspondence with each of the present engine speeds. A corresponding rate G/N is read out from the two-dimensional map in response to the calculated time duration t.

Abstract: A heat generating element having a thermal characteristic such that its resistance varies in response to changes in temperature is provided in the intake pipe of an engine. A heating power, the voltage of which is set by a reference voltage source, is supplied to the heat generating element via a transistor. The supply of this heating power is controlled by a start pulse signal periodically generated by a set flip-flop circuit when the ignition switch is on. When the heat generating element reaches a predetermined temperature, the supply is cut off by the flip-flop circuit. A measurement signal having a pulse width corresponding to the time period of heating power supply is generated from the flip-flop circuit. The opening of the ignition switch is detected and a one-shot multivibrator is driven to produce a burn-off signal having a pulse width to which the burn-off period corresponds.

Abstract: An air flowrate measuring apparatus with a heat wire measures the flow rate of the air flowing through the intake pipe of an engine. The apparatus has a temperature sensitive element which has a specific temperature-resistance characteristic and is disposed in the intake pipe. Constant heating voltage is applied to this element in response to a start signal, thus heating the element. When the temperature of the element rises to a specified value, the application of the voltage is stopped. At the same time, a pulse signal whose width corresponds to the period of applying the voltage is generated. The signal is supplied to an interface circuit through a drive circuit driven by a reference voltage which has been also used to control the heating voltage. The interface circuit comprises two wave-shaping circuits. The first wave-shaping circuit has a filter means of a small integration time constant.

Abstract: The intake airflow rate supplied to an internal combustion engine is measured and an obtained airflow rate measurement signal is used for detecting the operating state of the internal combustion engine. The internal combustion engine is electronically controlled, and an airflow rate measuring unit includes a heat-generating element having a temperature-resistance characteristic. A heating current which rises in correspondence with a signal synchronous with rotation of the engine is supplied to the heat-generating element. The heating current is controlled to rise when the heat-generating element is heated to a predetermined temperature, and the heating current duration indicates the airflow rate measurement signal. A burn-off command signal is generated so as to burn off dust attached to the heat-generating element. The command signal is used to generate a periodic signal having a preset effective duration.

Abstract: Disposed in an intake pipe of an engine is a temperature-sensitive element formed of a resistance element whose resistance value varies with temperature. A heating current is supplied to the temperature-sensitive element through a transistor. The voltage of the heating current is set by a constant-voltage circuit. The temperature of the temperature-sensitive element is compared with a reference temperature of an auxiliary temperature-sensitive element. When the temperature of the temperature-sensitive element is increased to a predetermined level, an output signal is delivered from a comparator. A flip-flop circuit is reset by the output signal from the comparator, and is set by a start pulse signal. When the flip-flop circuit is set, the transistor is turned on, allowing the heating current to be supplied to the temperature-sensitive element.

Abstract: An engine control method and apparatus generally applicable to those control systems of the engine such as an ignition system, fuel injection system, etc., which are controlled to optimum operation in accordance with the engine operating conditions. A plurality of angular pulses are generated during each rotation of the engine and these pulses are counted. In response to each pulse, an angular interrupt request is generated and the interrupt is performed in response thereto. The angular interrupt routines are of the highest priority and are executed irrespective of the execution status of the central processing unit to control an electric device associated with the engine in accordance with control data calculated by the central processing unit. Program interrupt requests are generated during selected angular interrupt routines when the counted number of angular pulses reaches a predetermined value.

Abstract: An engine control method generally applicable to those control systems of the engine such as an ignition system, fuel injection system, etc., which are controlled to optimum operation in accordance with engine operating conditions. Angular pulses are generated each time the output shaft of the engine rotates a predetermined angular amount. These angular pulses are counted from the occurrence of a position pulse which is generated at a predetermined angular position of the output shaft of the engine. A central processor is employed to calculate a first angular position at which an electric device for the engine is to be controlled. The central processor also calculates a time interval between the first angular position and a second angular position at which one of the angular pulses is to be provided just before the first angular position. When the angular pulse counting reaches a value corresponding to the second angular position, fixed frequency clock pulses are then counted.

Abstract: An ignition timing control method and an apparatus for internal combustion engines in which the ignition timing of the engine is calculated from a base value obtained by detecting a first operation state of the engine and from a learned correction value obtained in accordance with the record content of a nonvolatile memory, the ignition timing being corrected by rewriting the nonvolatile memory in accordance with the detection result of second and third driving states of the engine, as desired.

Abstract: In an electronic ignition control apparatus having RAM to initially store first and second signals indicative of the starting and terminating points for calculation of a time necessary for rotation of a predetermined angle defined by integer times as large as a predetermined angular interval of an output shaft of an engine, a rotation time of the output shaft is calculated during rotation of an angle of the output shaft defined by the first and second signals from RAM to calculate an optimum spark advance angle in relation to the operating condition of the engine such that an angular position defined by integer times as large as the predetermined angular interval at the advance angle side of the calculated advance angle is determined to be stored in RAM as a third signal.

Abstract: An engine control method generally applicable to those control systems of the engine such as an ignition system, fuel injection system, etc., which are controlled to optimum operation in accordance with the engine operating conditions. In this method, an operation starting timing and an operation ending timing of the control system, e.g., in the case of the ignition system, an ignition coil energization starting timing and an ignition timing (an energization ending timing) are computed at each of predetermined computing cycles, and the latest computed ignition timing, for example, which is computed after the coil energization has been started further taking into consideration of the actual coil energization timing and a minimum required energization period is compared with an ignition timing computed in the preceding computing cycle, and a corrective computation of the latest computed ignition timing is carried out depending on the result of the comparison to obtain an optimum ignition timing.

Abstract: Spark ignition timing of an internal combustion engine is oscillated on each side of a variable reference setting during successive ignition phases and the resultant engine speed is detected during at least three successive phases. The detected engine speed values are compared one against each other to determine whether they satisfy one of two specified conditions. The variable reference is adjusted in a direction toward an optimum position depending on which one of the conditions is satisfied. At least one of controlled parameters including the magnitude of the oscillated setting with respect to the variable reference, the length of the ignition phase and the amount of the adjusted reference setting, is varied as a function of an engine operating parameter.

Abstract: Spark ignition timing of an internal combustion engine is oscillated on each side of a variable reference setting by varying it at stepwisely variable amounts during positive and negative swings and the resultant engine speed is detected in at least three successive phases. The detected engine speed values are compared one against each other to determine whether they satisfy one of two specified conditions. The variable reference is adjusted in a direction toward an optimum position depending on which one of the conditions is satisfied.

Abstract: In an electronic ignition control apparatus having RAM to initially store first and second signals indicative of the starting and terminating points for calculation of a time necessary for rotation of a predetermined angle defined by integer times as large as a predetermined angular interval of an output shaft of an engine, a rotation time of the output shaft is calculated during rotation of an angle of the output shaft defined by the first and second signals from RAM to calculate an optimum spark advance angle in relation to the operating condition of the engine such that an angular position defined by integer times as large as the predetermined angular interval at the advance angle side of the calculated advance angle is determined to be stored in RAM as a third signal.

Abstract: An engine control method and apparatus generally applicable to those control systems of the engine such as an ignition system, fuel injection system, etc., which are controlled to optimum operation in accordance with the engine operating conditions. In this method, an operation starting timing and an operation ending timing of the control system, e.g., in the case of the ignition system, an ignition coil energization starting timing and an ignition timing (an energization ending timing) are computed at each of predetermined computing cycles, and the latest computed ignition timing, for example, which is computed after the coil energization has been started, further taking into consideration the actual coil energization timing and a minimum required energization period is compared with an ignition timing computed in the preceding computing cycle, and a corrective computation of the latest computed ignition timing is carried out depending on the result of the comparison to obtain an optimum ignition timing.