Abstract: In an in-cylinder injection internal combustion engine which is placed in a selected one of a compression stroke injection mode in which fuel injection is conducted during a compression stroke, and a suction stroke injection mode in which fuel injection is conducted during a suction stroke, depending upon operating conditions of the engine, a fuel control device cut a fuel to be supplied to a combustion chamber of the engine when a certain fuel cut condition set depending upon the operating conditions of the engine is established, and resumes fuel injection in a compression stroke injection mode when a predetermined fuel cut return condition is established. In this fuel control device, when the fully closed state of a throttle valve is detected by an idle switch, or the engine speed is reduced by a large degree, the fuel injection is resumed in an intake stroke injection mode upon return from the fuel cut, so as to prevent undershoot of the engine speed.

Abstract: A fuel control device for cylinder injection type internal combustion engines which is capable of cutting off fuel supplying to a combustion chamber depending upon an operating state of the engine and suitable for use in cylinder injection type engines, in which a compression stroke mode can be selected for the purpose of enabling shifting to fuel cutoff and shifting to fuel injection from cutoff without incurring shock of switching in the engine.

Abstract: In order to securely prevent knocks from occurring upon starting and the like, while enhancing the compression ratio in a spark ignition type in-cylinder injection internal combustion engine which includes a fuel injection valve for directly injecting fuel into a combustion chamber, fuel is injected during a compression stroke in a specific operation region under an intermediate to high load to perform stratified combustion. Further provided is a control unit for driving and controlling the fuel injection valve such that, in the stratified combustion, prior to the fuel injection during the compression stroke, fuel is injected from the fuel injection valve during an intake stroke by such an amount that fuel fails to self-ignite.

Abstract: In an in-cylinder injection internal combustion engine which is placed in a selected one of a compression stroke injection mode in which fuel injection is conducted during a compression stroke, and a suction stroke injection mode in which fuel injection is conducted during a suction stroke, depending upon operating conditions of the engine, a fuel control device cut a fuel to be supplied to a combustion chamber of the engine when a certain fuel cut condition set depending upon the operating conditions of the engine is established, and resumes fuel injection in a compression stroke injection mode when a predetermined fuel cut return condition is established. In this fuel control device, when the fully closed state of a throttle valve is detected by an idle switch, or the engine speed is reduced by a large degree, the fuel injection is resumed in an intake stroke injection mode upon return from the fuel cut, so as to prevent undershoot of the engine speed.

Abstract: A control apparatus for a cylinder fuel injection internal combustion engine in which a compression stroke injection mode for carrying out fuel injection mainly in a compression stroke and a suction stroke injection mode for carrying out fuel injection mainly in a suction stroke can be selected in accordance with the operational condition of the engine. The apparatus aiming at enabling a suitable suction correcting amount to be set for each operational mode of the engine and the improvement of drivability thereby being improved.

Abstract: When the rotation speed of an in-cylinder injection engine 1 reduces to a rotation speed for increasing the amount of air which has been set on a higher rotation speed side than a fuel supply-return rotation speed, the amount of air is increased. Thereafter, when the rotation speed of the in-cylinder injection engine 1 reduces to the fuel supply-return rotation speed, the supply of fuel is resumed in the fuel cut mode to securely prevent the rotation speed from lowering and to reduce a torque down during resumption of fuel-supply and deteriorated fuel consumption.

Abstract: A control apparatus for a cylinder-injection spark-ignition internal combustion engine, having a fuel injection valve for directly injecting fuel to a combustion chamber and controlling the fuel injection valve on the basis of either an intake stroke injection mode for effecting fuel injection mainly in the intake stroke and a compression stroke injection mode for effecting fuel injection mainly in the compression stroke. A fuel injection quantity correction device corrects at least the fuel injection quantity supplied to the combustion chamber and an intake air quantity correction device corrects the intake air quantity supplied to the combustion chamber so that the preset target idle speed is reached when an idle operation state is detected.

Abstract: An ignition timing control system is provided for an in-cylinder injection internal combustion engine to reduce a torque shock upon switching a fuel injection mode between a compression-stroke injection mode, in which an injection of fuel is performed primarily in a compression stroke, and an intake-stroke injection mode, in which an injection of fuel is performed primarily in an intake stroke, in accordance with an operation state of said internal combustion engine. The ignition timing control system is provided with an injection timing correction unit for correcting ignition timing of a spark plug, which is arranged in a combustion chamber, upon switching said fuel injection mode.

Abstract: In a combustion control device for an internal combustion engine provided with a plurality of fuel injection modes having different target air-fuel ratios, threshold values for detecting deterioration of combustion in the internal combustion engine are determined separately for each fuel injection mode depending on features of variation of combustion in the internal combustion engine in each fuel injection mode. Quantity of variation of combustion in the internal combustion engine is, for example, detected in the form of revolution angular acceleration or revolution angular acceleration deviation of the engine. The detected quantity of revolution fluctuation is compared with a threshold value in the currently chosen fuel injection mode. Thus, deterioration of combustion is surely judged according to each fuel injection mode. In particular, threshold values in a compression stroke injection mode are determined to be larger than threshold values in an intake stroke injection mode.

Abstract: A lean-burn internal combustion engine capable of stably securing a satisfactory vacuum for a vacuum actuator which uses a vacuum in an intake manifold disposed on the side downstream of an intake air amount control mechanism, while preventing a deterioration of a specific fuel consumption and a drivability of the engine. A filling state of gases in the intake manifold is controlled based on pieces of information in respect of an engine operating state and a reduction in vacuum, whereby a vacuum such as to ensure the operation of the vacuum actuator is secured. A control for inhibiting a lean-burn operation of the engine and for suppressing an EGR amount or inhibiting the EGR is made in accordance with an braking manipulation, the ON/OFF state of a vacuum switch, or an output from a vacuum sensor at the time of lean-burn operation.

Abstract: When starting of an in-cylinder injection engine 1 is detected, a cylinder discrimination, which discriminates each cylinder, is effected. After each cylinder is discriminated, it is determined whether or not a water temperature detected by a water temperature sensor 16 exceeds a predetermined value. When the water temperature is below the predetermined value, fuel injection is started from the fuel injection valve 4 of a cylinder subjected to at least one compression stroke. Thereby, the cylinder discrimination is effected quickly, and it is made possible to raise the temperature within the combustion chamber 5, by means lapse of at least one compression stroke, at low water temperatures at which the starting ability tends to be deteriorated, and the starting ability of the in-cylinder injection engine 1 at low water temperatures is improved while shortening the starting time.

Abstract: An engine control unit of a control apparatus for an in-cylinder injection internal combustion engine sets a fuel injection timing for a compression-stroke injection mode in accordance with a fuel injection quantity, and corrects the fuel injection timing according to an engine cooling water temperature. When the cooling water temperature is lower than a temperature observed when a warm-up operation is completed, the fuel injection timing for the compression-stroke injection mode is corrected for advance or retard on the basis of the engine characteristic proper, and fuel is injected at an appropriate time such that the fuel evaporation rate and the fuel stratification degree which permit the stabilized combustion of the fuel injected into the combustion chamber are attained, whereby the fuel is evaporated satisfactorily. Thus, the occurrence of misfire and the emission of harmful gas components can be restrained effectively during the warm-up operation in the compression-stroke injection mode.

Abstract: An alr-fuel ratio controller for-an internal-combustion engine is provided with front and rear O.sub.2 sensors respectively installed in the exhaust system on the upstream and downstream sides of an exhaust gas purifier. The controller corrects the air-fuel ratio in accordance with the result of the comparison between a detected value of the front O.sub.2 sensor and a first reference value, to thereby control the alr-fuel ratio to a desired value, and also corrects a value of a parameter related preferably to at least one of a correction amount or a correcting timing for the air-fuel ratio correction, e.g., the first reference value, in accordance with the deviation between a detected value of the rear O.sub.2 sensor and a second reference value.

Abstract: A control apparatus for a cylinder fuel injection internal combustion engine in which a compression stroke injection mode for carrying out fuel injection mainly in a compression stroke and a suction stroke injection mode for carrying out fuel injection mainly in a suction stroke can be selected in accordance with the operational condition of the engine. The apparatus aiming at enabling a suitable suction correcting amount to be set for each operational mode of the engine and the improvement of drivability thereby being improved.