Abstract: An air-fuel ratio control system for an internal combustion engine is comprised of an engine condition detecting unit and a control unit. The control unit is arranged to calculate a target engine torque on the basis of an engine operating condition, to calculate a target EGR ratio, a target excess air ratio and a target intake air quantity on the basis of the engine operating condition and the target engine torque, to calculate a target equivalence ratio on the basis of the target EGR ratio and the target excess air ratio, to calculate a target injection quantity on the basis of the engine operating condition and the target equivalence ratio, and to control an air-fuel ratio by bringing a real intake air quantity to the target intake air quantity and by bringing a real fuel injection quantity to the target fuel injection quantity.

Abstract: A control unit (41) controls an opening of an exhaust recirculation valve (6) according to a running condition of a diesel engine (1). The control unit (41) calculates an equivalence ratio of the gas mixture supplied to the engine (1) and a target intake fresh air amount taking account of the air amount in the exhaust gas recirculated by the exhaust gas circulation valve (6), based on the opening of the valve (6) and a target excess air factor of the engine (1) set according to the running condition. By controlling a turbocharger (50) according to the target intake fresh air amount, and by controlling the fuel supply mechanism according to a fuel injection amount calculated from the equivalence ratio, the excess air factor of the engine (1) and an exhaust gas recirculation rate of the exhaust gas recirculation valve (6) are respectively controlled to optimum values.

Abstract: In air-fuel ratio control apparatus and method for an internal combustion engine having an EGR valve interposed in an EGR passage between an intake manifold and an exhaust manifold, a target EGR quantity is calculated, a determination is made which of air-fuel ratio feedback controls through an EGR control and through an intake-air quantity is to be executed according to the target EGR quantity, and one of the air-fuel ratio feedback controls is selectively made according to a result of a determination of which of the air-fuel feedback controls is to be executed. During an execution of a rich spike control, the feedback control through the intake-air quantity control is unconditionally executed.

Abstract: A method for controlling an engine comprises establishing a torque correction coefficient (KA) to compensate for reducing effect of available engine torque in operating range of different excess air ratios (&lgr;) that are lower than a predetermined value (unity=1). An initial base desired in-cylinder air mass (tQacb) is determined based on a requested engine torque (tTe). A desired excess air ratio (t&lgr;) is determined. The initial base desired in-cylinder air mass (tQacb) is adjusted with at least the desired excess air ratio (t&lgr;) and the correction coefficient (KA) to generate a desired in-cylinder air mass (tQac). A desired injected fuel mass (tQf) is controlled based on the desired in-cylinder air mass (tQac) to deliver the requested engine torque (tTe) with the desired excess air ratio (t&lgr;) held accomplished.

Abstract: A basic target excess air factor tLAMBDA0 and a target fresh air intake amount tQac are set base upon the operation condition of an engine (30). A target excess air factor tLAMBDA is calculated by multiplying the ratio of a real fresh air intake amount rQac as detected by a sensor (16) and the target fresh air intake amount tQac by the basic target excess air factor tLAMBDA0. A fuel injector (9) is controlled so that the amount of fuel injected thereby converges to a target fuel injection amount tQf which corresponds to the target excess air factor tLAMBDA. It is possible to prevent variation of the output torque of the engine (30) accompanying a rich spike by this control, even if the basic target excess air factor tLAMBDA0 varies abruptly, since the fuel injection amount varies in correspondence to the variation of the real fresh air intake amount rQac.

Abstract: An air-fuel ratio control system for an internal combustion engine is comprised of an engine condition detecting unit and a control unit. The control unit is arranged to calculate a target engine torque on the basis of an engine operating condition, to calculate a target EGR ratio, a target excess air ratio and a target intake air quantity on the basis of the engine operating condition and the target engine torque, to calculate a target equivalence ratio on the basis of the target EGR ratio and the target excess air ratio, to calculate a target injection quantity on the basis of the engine operating condition and the target equivalence ratio, and to control an air-fuel ratio by bringing a real intake air quantity to the target intake air quantity and by bringing a real fuel injection quantity to the target fuel injection quantity.

Abstract: An electronic engine control system of an internal combustion engine with a supercharging device operable to produce a desired boost pressure, includes an electronically-controlled throttle valve and a pressure sensor located in an induction system to detect an actual boost pressure. The system computes a target air quantity used in a stratified combustion mode or in a homogeneous lean combustion mode, based on at least an operated amount of an accelerator, and computes the desired boost pressure based on engine speed and engine load, and computes a boost-pressure correction factor as the ratio of the desired boost pressure to the actual boost pressure, during the stratified combustion mode or during the homogeneous lean combustion mode. An arithmetic-calculation section is also provided to compensate for the target air quantity by the boost-pressure correction factor during the stratified combustion mode or during the homogeneous lean combustion mode.

Abstract: A throttle actuator varies an actual throttle valve opening degree for an engine in response to a control signal independently of driver's accelerator operation. An engine control unit determines a target torque (or a variable quantity representing the target torque) in accordance with an accelerator opening degree, and normally controls the actual throttle opening degree in a normal mode based on the target torque. In a predetermined operating region where the throttle opening responds too sensitively to a change in the target torque, the control unit controls the throttle opening degree in a constraint mode in accordance with a parameter, such as the accelerator opening degree, independent of the target torque.

Abstract: The disclosed control apparatus and method of an engine of the present invention calculates a target engine torque using an operation amount of an accelerator, converting the target engine torque into a first opening area of a throttle valve, calculates a required air amount at the time of idling, converting the required air amount into a second opening area of the throttle valve, calculates a target total opening area of the throttle valve by adding the first opening area and the second opening area of the throttle valve, calculates a target opening degree of the throttle valve in correspondence to the target total opening area, and outputs the target opening degree to the throttle valve controller which controls an opening degree of the throttle valve.

Abstract: An engine comprising a throttle controller operable in response to an intake air control command, a fuel controller operable in response to a fuel control command, and an engine controller for generating the intake air control command and the fuel control command. The engine controller determines a target equivalence ratio for detected operating state of the engine, controls a change between stratified charge combustion and homogeneous charge combustion, delays the target equivalent ratio, determines the intake air control command and the fuel control command in response to the delayed target equivalence ratio.

Abstract: In a control apparatus and method for a vehicular internal combustion engine, an accelerator operating variable detector is provided for detecting an operating variable of an accelerator operated by a driver, a revolution speed detector is provided for detecting a revolution speed of the engine, a driver demand torque calculator is provided for calculating an engine torque demanded by the vehicle driver on the basis of the detected operating variable of the accelerator and the detected revolution speed as a driver's demand torque.

Abstract: A torque controller for a direct-injection type internal combustion engine achieves the target engine torque accurately, without being affected by the combustion mode. The combustion efficiency is different depending on whether an engine combustion mode is in a homogeneous combustion mode or a stratified combustion mode. The torque controller calculates an eventual target intake air flow rate TTP2 based on the target intake air flow rate TTPO, the target air/fuel ratio tDML, and the combustion efficiency correction rate ITAF, which is calculated based on the combustion mode.

Abstract: A fuel injection control system for a cylinder direct injection spark-ignition internal combustion engine judges a homogeneous charge combustion condition which requires homogeneous charge combustion and a stratified charge combustion condition which requires stratified charge combustion, in accordance with an engine operating condition. Fuel is supplied on an intake stroke so as to form a rich equivalent ratio in the homogeneous charge combustion, and fuel is supplied on a compression stroke so as to form a lean equivalent ratio in the stratified charge combustion, with the rich equivalent ratio being richer in fuel than the lean equivalent ratio. The system then gradually changes over an equivalent ratio within a range between the rich and lean equivalent ratios when engine operation is changed over between the homogeneous charge combustion condition and the stratified charge combustion condition.

Abstract: A cylinder direct injection spark-ignition internal combustion engine comprising an EGR system is provided to control an amount of EGR gas recirculated from an exhaust gas passage to an intake air passage in which a throttle valve is disposed. The EGR system includes an EGR passage connecting the exhaust gas passage and the intake air passage, and an EGR valve disposed in the EGR passage. A control system is provided to control the EGR valve and the throttle valve. The control system includes a section for calculating a fresh air amount conversion value of an amount of the EGR gas, the fresh air amount conversion value being an amount of fresh air to be introduced to the intake system through the EGR system in place of the amount of the EGR gas. The control system further includes a section for controlling respective opening degrees of the throttle valve and the EGR valve in accordance with the fresh air amount conversion value.

Abstract: A predetermined firing delay time B.sub.1 is added to a value obtained by dividing a total gas weight Gcyl in a cylinder by an unburnt gas density basic value DENS and a laminar flow flame velocity basic value FLML. The value obtained by this calculation is unit converted and then set as a basic ignition timing for which a minimum ignition advance value or MBT is obtained. In this way, ignition timing control is optimized for various engine running conditions without preparing a plurality of maps.

Abstract: Fuel amounts injected by a fuel injection valve are summed from when an engine is started to when startup is complete. The temperature of a fuel-deposited part during engine startup is estimated, and an intake rate of a fuel injection amount to a combustion chamber is found from this temperature. A fuel deposition amount at completion of startup is estimated from the sum of fuel injection amounts and this intake rate. By increasing or decreasing the fuel injection amount after startup based on this fuel deposition amount, a post startup air-fuel ratio is rapidly stabilized unaffected by scatter of startup time.

Abstract: A warmup fuel amount corresponding to a predetermined heavy fuel is set to control an air-fuel ratio of an air-fuel mixture supplied to an engine during warmup. A correction amount based on a difference between a post-warmup engine speed variation and a first reference value is stored, and a warmup fuel amount decreased by this correction is supplied to the engine on the next startup occasion. In this way the sensitivity of air-fuel ratio control during startup when fuels of different nature are used, is enhanced.

Abstract: An engine provided with a purge valve introducing fuel vapor from the fuel tank into the intake passage, a purge valve for opening and closing the passage, a device for setting a basic flowrate of the purge valve according to the engine running conditions, and a device for detecting the fuel concentration of the purge gas. Further, a device is provided for correcting the basic flowrate based on the fuel concentration of the purge gas so as to decrease the purge valve flowrate when the fuel concentration is high, and increase the purge valve flowrate when it is low. The purge valve opening is controlled according to this corrected flowrate, and purging can therefore be performed rapidly without adversely affecting the air-fuel ratio.

Abstract: Fuel injection controller is provided for an engine having a purge passage for purging fuel vapor from the fuel tank into the intake passage, a purge valve which opens and closes the purge passage and a mechanism for feedback correcting a fuel injection amount based on a detected air-fuel ratio, The controller learns a feedback correction amount when the purge valve opens or closes, stores and updates a learning value according to the variation of the correction amount. When the variation of the learning value has converged to within certain region, the controller clamps the learning value, and corrects the fuel injection amount during purge based on this clamped value. Air-fuel ratio errors due to purging can therefore be rapidly reduced.

Abstract: A fuel supply amount is feedback controlled by a controller according to a feedback correction amount computed based on the output of an oxygen sensor installed in an exhaust pipe. An air-fuel ratio detected by this sensor is used to update a basic injection feedback correction amount which is a step fraction when there is a change-over of the air-fuel ratio, and an integral fraction when there is no change-over of the air-fuel ratio. This controller is further provided with a mechanism for detecting engine start-up, a mechanism for setting an initial value of a warm-up correction amount according to the engine temperature during start-up, a mechanism for computing a warm-up correction amount reduced according to the time elapsed after start-up, and a mechanism for adding this warm-up correction amount to said step fraction.