Abstract: In an estimation apparatus of an air intake flow for an internal combustion engine, an air intake flow rate fed into a portion just upstream of an intake valve at a predetermined timing before starting of fuel injection is calculated based on an output of an air flow meter. A variance in the air intake flow rate caused by the change in the intake pressure at the portion just upstream of the intake vale at the predetermined timing is calculated based on an output of a pressure sensor. The calculated air intake flow rate is added to the variance to obtain an air intake flow rate fed into a cylinder at the predetermined timing. The air intake flow rate fed into the cylinder is corrected to an air intake flow rate required for estimating an actual air intake flow based on an amount of change in the air intake flow rate fed into the cylinder at the predetermined timing.

Abstract: A plurality of intake air amount control devices for controlling an amount of air drawn into a combustion chamber in association with a depression stroke of an accelerator pedal are provided. Each of the intake air amount control devices responds to a change in depression stroke of the accelerator pedal after the lapse of a predetermined delay period.

Abstract: If during a specific steady operation state of an engine, the actual intake pipe pressure is different from a target intake pipe pressure set during the specific steady operation state, a first correction amount for the throttle valve control value is calculated by causing the actual intake pipe pressure to become equal to the target intake pipe pressure. If at this time the actual amount of intake air is still different from a target amount of intake air set during the specific steady operation state, a second correction amount for the variable valve control value is calculated by causing the actual amount of a intake air to become equal to the target amount of intake air. The second correction amount is used to further correct the throttle valve control value corrected by the first correction amount.

Abstract: A control apparatus is provided for a valve actuating system which is operable to lift an intake valve or an exhaust valve of an internal combustion engine and includes a lift characteristic changing mechanism for changing a lift characteristic of the intake valve or the exhaust valve. The control apparatus calculates a target operation value of the lift characteristic changing mechanism, and calculates a realizable range of the operation value which can be realized by the lift characteristic changing mechanism, based on a controlled variable that can be given to the lift characteristic changing mechanism and at least one parameter related to an environment surrounding the lift characteristic changing mechanism. If the target operation value is not within the realizable range of the operation value, the control apparatus calculates a new target operation value to be within the realizable range.

Abstract: A control system of an internal combustion engine includes a timing changing unit that changes opening and closing timing of an intake valve relative to rotation of an output shaft of the engine, a working angle changing unit that changes a working angle of the intake valve, a throttle mechanism including a throttle valve provided in an intake passage of the engine and an actuator that is operable to open and close the throttle valve, and an intake air quantity control unit that controls the timing changing unit, the working angle changing unit and the throttle mechanism so as to control an intake air quantity of the engine to a target intake air quantity. The control system detects a failure of at least one of the timing changing unit, the working angle changing unit and the throttle mechanism, and, upon detection of a failure, executes a selected one of difference fail-safe control processes corresponding to different forms of failures, depending upon the form of the detected failure.

Abstract: A device for controlling an internal combustion engine, comprising a variable valve mechanism for varying opening areas (valve lift) or the working angles (valve-opening periods) of at least either the intake valves or the exhaust valves, wherein a pressure in the cylinder is calculated based on the opening area or the working angle of at least either the intake valve or the exhaust valve varied by the variable valve mechanism, and the internal combustion engine is controlled based on the pressure in the cylinder. Upon calculating the pressure in the cylinder based on the opening areas or the working angles of the intake and exhaust valves, it is possible to more suitably control the internal combustion engine based not only upon the peak combustion pressure in the cylinder like when a combustion pressure sensor is used but also upon a pressure in the cylinder at a moment other than the peak combustion pressure.

Abstract: An engine is operated in a homogeneous charge combustion mode or a stratified charge combustion mode. An intensive target throttle angle is computed based on the running state of the engine, regardless of a combustion mode which is underway. The intensive target throttle angle reflects an engine torque which is demanded at the time of executing the homogeneous charge combustion mode. At the time of executing the homogeneous charge combustion mode, the degree of opening of a throttle valve is adjusted based on the intensive target throttle angle to adjust the engine torque. At the time of executing the stratified charge combustion mode, a fuel injection amount is adjusted based on the intensive target throttle angle to adjust the engine torque. In other words, even in case where either of the two combustion modes is executed, the engine torque is adjusted based on the intensive target throttle angle.

Abstract: An engine can switch a combustion mode between homogeneous charge combustion and stratified charge combustion. The engine is controlled in accordance with a load acting on the engine. When homogeneous charge combustion is executed, an intake pressure, or a parameter representing the amount of intake air, is used as a value representing an engine load. When stratified charge combustion is executed, a value equivalent to the intake pressure presuming homogeneous charge combustion is executed with the amount of manipulation of an acceleration pedal at that time is computed as a virtual intake pressure, and the virtual intake pressure is used as a value representing the engine load. In either combustion mode, therefore, the intake pressure, or a common parameter, is used as a value representing the engine load to control the engine. This simplifies matching of engine power torques between both combustion modes.

Abstract: An air-fuel ratio control apparatus of an internal combustion engine according to the present invention is provided with oxygen storage amount estimating means, downstream exhaust air-fuel ratio detecting means, maximum oxygen storage amount estimating means, and air-fuel ratio target setting means. The oxygen storage amount estimating means estimates an oxygen storage amount of an exhaust purifying catalyst, based on a history of an oxygen adsorption/desorption amount of the exhaust purifying catalyst located on an exhaust path. The downstream exhaust air-fuel ratio detecting means is located downstream of the exhaust purifying catalyst and detects an exhaust air-fuel ratio downstream of the exhaust purifying catalyst. The maximum oxygen storage amount estimating means estimates a maximum oxygen storage amount, based on an oxygen storage amount estimate when the exhaust air-fuel ratio detected is a predetermined air-fuel ratio.

Abstract: An air-fuel ratio control apparatus of an internal combustion engine according to the present invention is provided with oxygen storage amount estimating means, downstream exhaust air-fuel ratio detecting means, maximum oxygen storage amount estimating means, and air-fuel ratio target setting means. The oxygen storage amount estimating means estimates an oxygen storage amount of an exhaust purifying catalyst, based on a history of an oxygen adsorption/desorption amount of the exhaust purifying catalyst located on an exhaust path. The downstream exhaust air-fuel ratio detecting means is located downstream of the exhaust purifying catalyst and detects an exhaust air-fuel ratio downstream of the exhaust purifying catalyst. The maximum oxygen storage amount estimating means estimates a maximum oxygen storage amount, based on an oxygen storage amount estimate when the exhaust air-fuel ratio detected is a predetermined air-fuel ratio.

Abstract: An apparatus for accurately detecting the amount of engine intake air based on the amount of air flowing past an air flow meter in an internal combustion engine equipped with a variable intake air control mechanism capable of varying the operating condition of an intake air control valve that controls the flow of intake air into a combustion engine. A smoothing factor is computed in such a manner that the smoothing factor is reduced to increase the degree of smoothing when volumetric efficiency decreases depending on the operating condition of the intake air control valve. The amount of engine intake air is computed by smoothing the flow rate of air measured by the air flow meter, based on the smoothing factor. Further, volumetric efficiency is computed based on engine load and engine speed as well as on the operating condition of the intake air control valve, and the smoothing factor is calculated based on the thus computed volumetric efficiency.

Abstract: A control apparatus calculates a exhaust gas air-fuel ratio of a plurality of cylinders, in which the operation angle of an intake valve is set to a predetermined operation angle, e.g., a maximum operation angle, based on a value output from an air-fuel ratio sensor so as to minimize a variation in an fuel injection quantity between the plurality of cylinders by that exhaust gas air-fuel ratio. That is, the exhaust gas air-fuel ratio of the plurality of cylinders, in which the valve opening characteristics of the intake valve and an exhaust valve are set such that the intake air amount to be introduced into the plurality of cylinders is limited by the opening amount of a throttle valve, for example, and not limited by the valve opening characteristics of the intake valve or the exhaust valve is calculated, and the variation in the fuel injection quantity among the plurality of cylinders is then reduced by that exhaust gas air-fuel ratio.

Abstract: An exhaust manifold (7) of an engine (1) is connected to a three way (TW) catalyst (8a), and the TW catalyst (8a) is connected to an NH3 adsorbing and oxidizing (NH3-AO) catalyst (10a). The engine (1) performs the lean and the rich engine operations alternately and repeatedly. When the engine (1) performs the rich operation and thereby the exhaust gas air-fuel ratio of the exhaust gas flowing into the TW catalyst (8a) is made rich, NOx in the inflowing exhaust gas is converted to NH3 in the TW catalyst (8a). The NH3 is then adsorbed in the NH3-AO catalyst (10a). Next, when the engine (1) performs the lean operation and thereby the exhaust gas air-fuel ratio of the exhaust gas flowing into the TW catalyst (8a) is made lean, NOx in the exhausted gas passes through the TW catalyst (8a), and flows into the NH3-AO catalyst (10a). At this time, NH3 adsorbed in the catalyst (10a) is desorbed therefrom, and reduces the inflowing NOx.

Abstract: An air-fuel ratio control apparatus of an internal combustion engine according to the present invention is provided with oxygen storage amount estimating means, downstream exhaust air-fuel ratio detecting means, maximum oxygen storage amount estimating means, and air-fuel ratio target setting means. The oxygen storage amount estimating means estimates an oxygen storage amount of an exhaust purifying catalyst, based on a history of an oxygen adsorption/desorption amount of the exhaust purifying catalyst located on an exhaust path. The downstream exhaust air-fuel ratio detecting means is located downstream of the exhaust purifying catalyst and detects an exhaust air-fuel ratio downstream of the exhaust purifying catalyst. The maximum oxygen storage amount estimating means estimates a maximum oxygen storage amount, based on an oxygen storage amount estimate when the exhaust air-fuel ratio detected is a predetermined air-fuel ratio.

Abstract: A direct-injection internal combustion engine can smoothly switch and transition between a first operation mode and a second operation mode according to an operating condition of the engine. An engine control amount in the first operation mode is calculated differently from an engine control amount in the second operation mode. However, even if the engine control amount requires correction only in the second operation mode, calculation of a correction amount is made during the first operation mode as well. During a transition from the first operation mode to the second operation mode, the correction amount calculated during the first operation mode is taken into account in calculating an engine control amount. As the correction amount is already available at the time of transition, a suitable engine control amount can be immediately obtained.

Abstract: A controller for an internal combustion engine that switches combustion modes in accordance with the running conditions of the engine. When there is a need to reduce the engine torque, the controller decreases the torque by a predetermined torque reduction method. The controller decreases the engine torque by a first torque reduction method when the engine is in a first combustion mode. When the engine is in a second combustion mode, the controller reduces the torque by a second torque reduction method. The controller sets a first control amount, which corresponds to the torque reduction requirement, according to one of the first and second torque reduction methods. The controller converts the first control amount into a second control amount, which corresponds to the other torque reduction method.

Abstract: An air-amount-first fuel-amount-second control apparatus for an internal combustion engine having an electronically-controlled throttle valve. The response characteristic of the throttle valve is stored, a target value of the throttle valve opening degree corresponding to the operating position of the accelerator pedal is calculated, the intake air valve closing time of the fuel injection cylinder is calculated in accordance with the engine operating condition, the time required for reaching a target throttle valve opening degree is calculated from the target throttle valve opening degree and the stored value of the response characteristic of the throttle valve, the throttle valve opening degree as of the intake air valve closing time is calculated from the calculated time required for reaching the target throttle valve opening degree and the intake air valve closing time of the fuel injection cylinder.

Abstract: In an exhaust gas purification device, a No. 1 cylinder of the engine is operated at a rich air-fuel ratio and other cylinders (No. 2 to No. 4) are operated at a lean air-fuel ratio. The exhaust gases from the No. 1 and No. 2 cylinders are mixed with each other to form a rich air-fuel ratio exhaust gas mixture. Further, since the air-fuel ratio of the No. 2 cylinder is lean, the exhaust gas from the No. 2 cylinder contains a relatively large amount of NO.sub.x. This rich air-fuel ratio exhaust gas mixture which contains a relatively large amount of NO.sub.X is supplied to a three-way catalyst. At the three-way catalyst, part of the NO.sub.X in the exhaust gas mixture is converted to NH.sub.3. The exhaust gas mixture flowing out from the three-way catalyst and the lean exhaust gas from the No. 3 and No. 4 flow into a common exhaust gas passage where they mix with each other to form a lean exhaust gas containing NH.sub.3 from the three-way catalyst and NO.sub.X from the No. 3 and No. 4 cylinders.

Abstract: A apparatus and method for adjusting the amount of air introduced into a cylinder of an internal combustion engine. An intake passage is connected to the cylinder for introducing air. An intake valve is provided in the intake passage for cyclically opening and closing the cylinder. An injector is provided in the intake passage for injecting fuel. A throttle valve is positioned in the intake passage for adjusting an amount of air flow into the cylinder. An electronic control unit (ECU) controls the position of the throttle valve. The ECU closes the intake passage to decrease the pressure in the intake passage when cranking is started. The ECU moves the throttle valve to a first open position .theta.2 to increase the amount of air introduced into the cylinder after a predetermined time period elapses from the start of engine cranking. The ECU moves the throttle valve to an open position .theta.1 when the engine starts.

Abstract: A fuel supplying apparatus and method for supplying a cylinder of an internal combustion engine with fuel. An intake passage is connected to the cylinder for introducing air to the cylinder. An intake valve and an injector are provided in the intake passage. A throttle valve is positioned in the intake passage for adjusting the amount of air flow into the cylinder. An electronic control unit (ECU) controls the position of the throttle valve. The ECU controls the throttle valve to decrease the pressure in the intake passage when cranking is started. The ECU estimates the pressure adjacent to the intake port based on the engine speed and a time period measured from the start of cranking. The ECU also estimates what the intake port pressure will be when the intake valve is subsequently closed. The ECU computes an amount of fuel to be injected based on the pressure that was estimated based on a closed intake valve, and controls the injector to inject the computed amount of fuel.