Abstract: An engine speed control apparatus including an air control valve which controls the cross-sectional area of a bypass passage provided so as to bypass the throttle valve of the engine. The apparatus also includes a control unit which controls a degree of opening of the air control valve on the basis of a synthesized quantity which is obtained by synthesizing a basic air quantity for maintaining a target engine speed and an engine speed feed-back correction quantity which effects to eliminate an error between the target speed and an actual engine speed. An atmosphere pressure sensor is used to detect an atmospheric pressure, and a correction circuit is used to ensure that the synthesized quantity corresponds with the detected atmospheric pressure the engine is started.

Abstract: An engine speed control apparatus capable of controlling the idling speed of an engine without entailing abnormal rise or fall of engine speed while the engine is in operation in an idling mode.

Abstract: An idle revolution speed control apparatus for an internal combustion engine comprises a detecting means to detect an electric quantity produced at an electricity generating unit consisting of a generator and a generator control device, an electricity variation quantity calculating means to calculate a variation quantity with respect to the electric quantity obtained by the detecting means, a correction quantity calculating means to calculate an idle revolution speed correction quantity on the basis of data obtained by the detecting means and the electricity variation quantity calculating means, and an adding means for adding the correction quantity obtained by the correction quantity calculating means.

Abstract: An engine revolution control apparatus for a vehicle, in which revolutions of an engine when the engine is in the idling state, e.g., when the vehicle is being stopped and a throttle valve is totally closed, is controlled by controlling the opening of an air control valve which is provided in a by-pass conduit for by-passing the throttle valve according to a revolution feedback correction volume. The revolution feedback correction volume is calculated according to the deviation between the actual revolutions of the engine and its target revolutions which was set according to the load of the engine, increasing, in the non-idling state of the engine, the revolution feedback correction volume, which is calculated when the engine has shifted from the idling state to the non-idling state as well as when the deviation between the actual revolutions and the target revolutions is small.

Abstract: An improved idle speed control apparatus for an internal combustion engine capable of effectively preventing instantaneous fluctuations in the number of revolutions per minute of the engine when the engine load is instantaneously changed during engine idling, thereby improving the driver's driving sensation. A bypass passage is connected with an intake manifold of the engine for supplying intake air to the engine while bypassing a throttle valve in the intake manifold. A bypass air controller is disposed on the bypass passage for controlling the amount of bypass air flowing therethrough. In one embodiment, the bypass air controller operates such that when the engine load is altered instantaneously during the engine idling, the amount of intake air is gradually changed from a first level suited to a first operating condition of the engine load to a second level suited to a second opeating condition of the engine load.

Abstract: An idle speed adjusting system for effecting feedback control of the idle speed of an internal combustion engine comprises a reference control amount output circuit for producing and delivering a reference control signal necessary for maintaining a command engine speed; a speed controller for generating a speed correction signal representing the offset of the running speed of the engine from the command engine speed; a flow rate controller for controlling the flow rate of intake air supplied to the engine, in accordance with the reference control signal and the speed correction signal; and an auxiliary flow rate controller for controlling the flow rate of the intake air in accordance with the speed correction signal and independently of the flow rate controller, so as to adjust the speed correction signal to a predetermined value.

Abstract: A backup apparatus for ignition and fuel system provided with an ignition system backup circuit and a fuel system backup circuit to be used in case of a breakdown of a main circuit. The fuel system backup circuit outputs a drive signal to a fuel injection valve by using either an ignition signal for an ignition device from the ignition system backup circuit, or an ignition diagnosis signal from the ignition device as a trigger timing. When the ignition system backup circuit breaks down, neither the ignition signal from the ignition system backup circuit nor the ignition diagnosis signal from the ignition, device is generated, so that the supply of fuel to the engine is stopped.