Abstract: A fuel injection control system for internal combustion engine comprises a fuel injection pump including a plunger slidably reciprocating in synchronism with rotation of the engine and a spill port establishing communication between a low pressure chamber and a pump chamber. An electronic control unit is responsive to engine operating conditions for the determination of fuel injection time period and controls the solenoid-operated valve to close the spill port in response to the requirement of fuel injection into the cylinder and open the same to terminate the fuel injection. The fuel injection control system further comprises a circuit including two fixed resistors and two adjusting resistors so that first and second voltage signals are developed at its terminals. The two adjusting resistors respectively determine the value of the voltage signals.

Abstract: In controlling a fuel injection quantity by spilling a part of fuel fed from a high pressure chamber of a fuel injection pump using a high pressure electromagnetic valve which is on-off controlled by a driving circuit in accordance with engine operating conditions, switch means is provided between the high pressure electromagnetic valve and a power source, an output signal from the driving circuit is monitored, and the switch means is opened when the output signal from the driving circuit continues more than a predetermined period.

Abstract: A combustion process sensor for detecting combustion processes occurring in a combustion chamber of an engine has a generally tubular mounting casing to be screwed into a threaded hole in the combustion chamber wall and a quartz-glass rod axially extending in the mounting casing and held in position therein. The casing includes two axially aligned generally tubular members rigidly secured together at their own ends. The quartz-glass rod has a first portion remote from a sensing end thereof adapted to be exposed to combustion flame in the combustion chamber, and a second portion between the first portion and the sensing end. The first portion is secured to one of the two tubular members of the casing, while the second portion is supported from the casing only by a vibration damping material disposed in engagement with the outer peripheral surface of the quartz-glass rod and the inner peripheral surface of the casing.

Abstract: A crank angle sensor generates a reference position signal and a crank angle signal as an internal combustion engine rotates. A counter counts the crank angle signals and, when its count value has reached a first set value, it goes to a second set value. Where the count value of the counter changed from the first to the second set value before the generation of the reference position signal, a control circuit sets the counter to the second set value when the reference position signal is generated. Where the count value of the counter did not change from the first to the second set value before the generation of the reference position signal, the control circuit sets the counter to the second set value when the counter is at the first set value and the reference position signal is produced.

Abstract: A stepping motor is driven such that a rotational speed of an engine falls within a range of a target rotational speed determined in accordance with at least an engine coolant temperature when a throttle valve is substantially fully closed, in order to control an opening area of an air flow rate control valve. In the control operation, a lower limit of the opening area of the control valve is set to prevent the opening area from being reduced beyond a predetermined area in order to prevent engine stall. A predetermined setting is stored in a predetermined area each time when a vehicle speed signal from a vehicle speed sensor is received and the predetermined setting is decremented under a predetermined condition. When the decremented setting reaches zero, a current lower limit is maintained.

Abstract: An idling speed control device of an internal combustion engine comprising a bypass passage which interconnects the intake passage located upstream of the throttle valve to the intake passage located downstream of the throttle valve. A flow control valve is arranged in the bypass passage and actuated by a step motor for controlling the amount of air flowing within the bypass passage to maintain the idling speed of an engine at a predetermined speed. The step motor comprises a screw threaded valve shaft and a rotor rotatably mounted on the valve shaft and having a screw threaded center hole which is in engagement with the screw threads of the valve shaft. A pair of stop pins, each being engageable with the corresponding end face of the rotor, is fixed onto the valve shaft.

Abstract: The idle air flow to an engine is increased or decreased in response to a control signal which is produced by comparing actual engine speed with a desired idle speed. Whether the above increase or decrease operation is continuously repeated more than a certain times is discriminated. If it is repeated more than the certain times, whether the variation of the engine speed during the above continuous increase or decrease operation is less than a predetermined value is discriminated. When the engine-speed variation during the above increase or decrease operation is less than the predetermined value, the idle speed control operation is inhibited from being executed.

Abstract: An engine comprising a main intake passage having a throttle valve therein. A bypass passage is branched off from the main intake passage located upstream of the throttle valve and is connected to the main intake passage located downstream of the throttle valve. A flow control valve, actuated by a step motor, is arranged in the bypass passage. The step motor comprises a rotor and a stator having exciting coils. When the engine is operating in an idling state, the exciting coils are excited for rotating the step motor in a rotating direction wherein the engine speed approaches a desired idling speed. When the engine speed becomes equal to the desired engine speed and is higher than a predetermined speed, the exciting coil, which was finally excited immediately before the engine speed becomes equal to the desired idling speed, is intermittently excited in order to maintain the step motor stationary.

Abstract: An engine comprising a main intake passage having a throttle valve therein. A bypass passage is branched off from the main intake passage located upstream of the throttle valve and is connected to the main intake passage located downstream of the throttle valve. A flow control valve, actuated by a step motor, is arranged in the bypass passage. The step motor comprises a rotor and a stator having exciting coils. When the engine is operating in an idling state, the exciting coils are excited for rotating the step motor in a rotating direction wherein the engine speed approaches a desired idling speed. When the engine speed becomes equal to the desired engine speed, the exciting operation of the exciting coils is stopped.

Abstract: An idling speed control device of an internal combustion engine comprising a bypass passage which interconnects the intake passage located upstream of the throttle valve to the intake passage located downstream of the throttle valve. A flow control valve is arranged in the bypass passage and actuated by a step motor for controlling the amount of air flowing within the bypass passage to maintain the idling speed of an engine at a predetermined speed. The step motor comprises a screw threaded valve shaft and a rotor rotatably mounted on the valve shaft and having a screw threaded center hole which is in engagement with the screw threads of the valve shaft. The valve shaft is supported by bearings so that the valve shaft cannot be rotated, but is able to move in the axial direction.

Abstract: An idling speed control device of an internal combustion engine comprising a bypass passage which interconnects the intake passage located upstream of the throttle valve to the intake passage located downstream of the throttle valve. A flow control valve is arranged in the bypass passage and actuated by a step motor for controlling the amount of air flowing within the bypass passage to maintain the idling speed of an engine at a predetermined speed. A cooling water passage is formed in the valve housing of the flow control valve.

Abstract: An engine has a main intake passage in which a throttle valve is disposed. A bypass passage is branched off from the main intake passage upstream of the throttle valve and is connected to the main intake passage located downstream of the throttle valve. A flow control valve, actuated by a stepper motor, is arranged in the bypass passage. In an electronic control unit, the mean value of the step position is stored, and a lower limit of the step position is calculated from the mean value of the step position. When the engine is idling after it has been and the stepper motor is rotated in a direction wherein the flow control valve closes the rotating operation of the stepper motor is stopped when the step position of the stepper motor reaches thelower limit of the step position. This allows for precise control of the flow control valve, while preventing the sudden rapid closing of the valve, thus improving engine performance.

Abstract: An engine comprising a main intake passage having a throttle valve therein. A bypass passage is branched off from the main intake passage located upstream of the throttle valve and is connected to the main intake passage located downstream of the throttle valve. A flow control valve, actuated by a step motor, is arranged in the bypass passage. When the engine is operating in an idling state, the step motor is rotated at a first speed in a rotating direction wherein the engine speed approaches a desired engine speed. When the ignition switch is turned to the OFF position for stopping the engine, the step motor is rotated at a second speed which is lower than the first speed a little while after the flow control valve fully opens the bypass passage.

Abstract: An idling rotational speed control device wherein, when an engine ignition switch is turned off, an air flow rate control device is driven to a fully closed position or a fully opened position, and the air flow rate control valve is controlled referenced from the fully closed position or the fully opened position as the new reference position. During idling, the flow rate of air taken into an intake manifold is controlled by the intentional opening degree from the reference position of the air flow rate control valve so as to correctly perform control.

Abstract: Ignition timing is controlled in accordance with the engine's operating condition during the time the engine is in a normal operating condition. However, during the starting condition, the ignition timing is fixed to the top dead center in the compression stroke of each cylinder to be ignited.

Abstract: A spark advance angle corresponding to an optimum ignition timing is calculated in accordance with the operating condition of an internal combustion engine. Then, a reference crank angle position utilized for controlling the ignition timing is selectively determined in accordance with the value of the calculated spark advance angle so as to reduce any error in the ignition timing resulting from a change of the rotational speed of the engine.

Abstract: An idling speed control device of an internal combustion engine comprising a bypass passage which interconnects the intake passage located upstream of the throttle valve to the intake passage located downstream of the throttle valve. A flow control valve is arranged in the bypass passage and actuated by a step motor for controlling the amount of air flowing within the bypass passage to maintain the idling speed of an engine at a predetermined speed.

Abstract: An engine includes a main intake passage having a throttle valve therein. A bypass passage branches off from the main intake passage upstream of the throttle valve and connects again to the main intake passage downstream of the throttle valve. A flow control valve, actuated by a step motor, is arranged in the bypass passage. When the speed difference between the desired idling speed and the actual idling speed is higher than 20 r.p.m., the step motor is rotated in a direction wherein the actual idling speed approaches the desired speed. Contrary to this, when the above-mentioned speed difference is lower than 20 r.p.m., the step motor remains stationary.

Abstract: A time period during which current is conducted through a primary winding of an ignition coil of an internal combustion engine is calculated in response to signals corresponding to an actual rotational speed of the engine and the magnitude of a power supply voltage which is applied to the primary winding, respectively. A time for initiating the primary winding current is controlled in accordance with the calculated time period. Such current is conducted for a maximum period of time, which is determined in response to the magnitude of the power supply voltage, so as to avoid excessive heat build-up in the ignition coil. The rotational speed of the engine is determined by counting clock signals during time intervals which correspond to predetermined angular segments of rotation.

Abstract: An electronic ignition control device for determining and maintaining a vehicle at the optimum spark advance for different ranges of crankshaft rotation speeds and ratios of air intake to crankshaft rotation speed. Signals indicating a range in which the instantaneous rotation speed falls and a range in which air intake/speed ratio falls define a ROM address at which is stored an optimum spark advance angle for that combination of ranges. The signal indicating the stored angle is applied to a discriminator which also receives inputs from a crank switch monitor, a throttle switch monitor and a coolant temperature sensor. When cranking or idling is detected, the discriminator substitutes a cranking advance or idling advance angle for the stored optimum advance angle signal.