Abstract: An electronic control unit for an internal combustion engine that includes an engine-driven alternator diagnoses on the bases of an air-fuel ratio correction amount in air-fuel ratio feedback control whether a rich abnormality that the air-fuel ratio of air-fuel mixture is excessively rich is occurring in a fuel injection system. When the state of charge of a battery charged with electric power generated by the alternator is higher than or equal to a predetermined value, charging control for setting a voltage generated by the alternator at a voltage lower than a normal generated voltage is executed. When the state of charge of the battery is higher than or equal to the predetermined value, charging control for charging the battery at the voltage is prohibited when a degree of mixing of fuel in lubricating oil of the internal combustion engine is higher than or equal to a predetermined degree.

Abstract: In a vehicle having mounted therein an engine including an injector that directly injects fuel into a cylinder, in the case in which a warm-up control required condition is established, catalyst warm-up control is executed if an amount of fuel diluted in oil is low, or even if the amount of fuel diluted in oil is high, when the temperature of the engine oil is less than the fuel volatilization temperature. In contrast, even in the case in which the warm-up control required condition is established, if the amount of fuel diluted in oil is greater than or equal to a determination value, and furthermore the temperature of the engine oil is greater than or equal to the fuel volatilization temperature, there is the possibility of negative influence on exhaust emissions, and therefore the catalyst warm-up control is prohibited.

Abstract: The engine ECU executes a program including the step of setting an upper limit guard value of a fuel pressure by executing low fuel pressure control in the case where a low fuel pressure control execution condition is satisfied with fulfillment of conditions that execution of the low fuel pressure control is permitted, that engine speed NE is lower than a threshold value, and that the atmospheric pressure is higher than a threshold value, and the step of controlling the fuel pressure to be a target fuel pressure within a range not exceeding the upper limit guard value.

Abstract: If two-split injection logic has been adopted, an engine ECU executes a program including the steps of calculating first injection start timing of the two-split injection logic, calculating second injection start timing of the two-split injection logic, calculating a first injection permitted time period A of the two-split injection logic, calculating a first injection required time period B of the two-split injection logic, and adopting single injection logic instead of the two-split injection logic if the first injection start timing A of the two-split injection logic is shorter than the first injection required time period B of the two-split injection logic.

Abstract: The engine ECU executes a program including the step (S320) of setting an upper limit guard value of a fuel pressure by executing low fuel pressure control in the case where a low fuel pressure control execution condition is satisfied with fulfillment of conditions that execution of the low fuel pressure control is permitted, that engine speed NE is lower than a threshold value, and that the atmospheric pressure is higher than a threshold value (S310), and the step (S330) of controlling the fuel pressure to be a target fuel pressure within a range not exceeding the upper limit guard value.

Abstract: A controller for a direct-injection internal combustion engine in which fuel is directly injected into a combustion chamber via a fuel injection valve, and a mixture formed thereby is burned by igniting the mixture via an ignition plug, which the controller, when the internal combustion engine is started under very low temperature conditions, controls an ignition cut operation that inhibits ignition and performs fuel injection only, the controller including an engine-start control unit that, when the internal combustion engine is started under very low temperature conditions after the ignition cut operation was performed, determines whether there is fuel that can contribute to combustion in a cylinder and if there is, inhibits the ignition cut operation, or limits a number of times of the cutting off of ignition.

Abstract: An engine ECU executes a program including: the step of outputting a fuel-cut instruction when conditions that an accelerator position PA is not higher than a threshold value and a rate of increase DNE of engine speed NE is not lower than a determination value DNE(0) are satisfied; the step of fully closing throttle opening; and the step of suspending ignition of air-fuel mixture by a spark plug.

Abstract: An internal combustion engine has a fuel injection valve. To cause an actual air-fuel ratio of air-fuel mixture burned in the engine to be equal to a target value, an electronic control device corrects a fuel injection amount from the fuel injection valve using a feedback correction value. The feedback correction value is changed based on the actual air-fuel ratio. The electronic control device computes, as a safeguard value, a value of the feedback correction value that causes a fuel injection time, which is an instruction sent to the fuel injection valve, to be a permissible minimum time. When the fuel injection time is less than the permissible minimum time, the electronic control device limits the lowest value of the feedback correction value to the safeguard value. As a result, the actual air-fuel ratio is prevented from being rich.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine according to the invention includes a control unit that makes a correction to the fuel injection amount using the air-fuel ratio learned value when calculating the fuel injection amount, and that changes the guard value that places a limitation on the degree of correction to the fuel injection amount made by using the air-fuel ratio learned value, based on the degree to which lubricating oil has been diluted with fuel.

Abstract: A fuel injection control apparatus for a direct injection type internal combustion engine according to the invention includes a control unit. The control unit estimates the degree to which lubricating oil, which is used in the internal combustion engine, has been diluted with fuel based on the length of time the internal combustion engine has been running, and an accumulated value that indicates an amount of air that has been taken in by the internal combustion engine while the internal combustion engine has been running or an accumulated value that indicates an amount of fuel that has been injected while the internal combustion engine has been running. The control unit determines the amount of fuel to be injected based on the degree of dilution.

Abstract: An engine ECU executes a program including: the step of outputting a fuel-cut instruction when conditions that an accelerator position PA is not higher than a threshold value and a rate of increase DNE of engine speed NE is not lower than a determination value DNE(0) are satisfied; the step of fully closing throttle opening; and the step of suspending ignition of air-fuel mixture by a spark plug.

Abstract: It is determined whether there is a fuel-injection history when the engine is started under very low temperature conditions. If there is the fuel-injection history, a current number of times cutting off ignition is to be performed is calculated, using a requested number of times of cutting off of ignition, and a recorded number of times of fuel injection in the fuel-injection history during cutting off ignition that was performed when it was attempted to start the engine last time. Cutting off ignition is performed based on the calculated value.

Abstract: A controller for controlling valve timing imbalance between cylinder groups of an engine. For each cylinder group, the controller has a variable mechanism for varying the valve timing. A lock mechanism locks the variable mechanism so as to maintain the valve timing of the cylinder group at a lock value. An ECU sets a valve timing target value based on the operating condition of the engine. The ECU and an oil control valve drive the variable mechanism. The ECU restricts the valve timing target value of at least one of the variable mechanisms of which operation is unlocked when the operation of at least one of the variable mechanisms is locked so that difference between the target value and the lock value decreases.

Abstract: An air-fuel ration control apparatus for an internal combustion engine according to the invention includes a control unit that makes a correction to the fuel injection amount using the air-fuel ration learned value when calculating the fuel injection amount, and that changes the guard value that places a limitation on the degree of correction to the fuel injection amount made by using the air-fuel ration learned value, based on the degree to which lubricating oil has been diluted with fuel.

Abstract: A fuel injection control apparatus for a direct injection type internal combustion engine according to the invention includes a control unit. The control unit estimates the degree to which lubricating oil, which is used in the internal combustion engine, has been diluted with fuel based on the length of time the internal combustion engine has been running, and an accumulated value that indicates an amount of air that has been taken in by the internal combustion engine while the internal combustion engine has been running or an accumulated value that indicates an amount of fuel that has been injected while the internal combustion engine has been running. The control unit determines the amount of fuel to be injected based on the degree of dilution.

Abstract: An internal combustion engine has a fuel injection valve. To cause an actual air-fuel ratio of air-fuel mixture burned in the engine to be equal to a target value, an electronic control device corrects a fuel injection amount from the fuel injection valve using a feedback correction value. The feedback correction value is changed based on the actual air-fuel ratio. The electronic control device computes, as a safeguard value, a value of the feedback correction value that causes a fuel injection time, which is an instruction sent to the fuel injection valve, to be a permissible minimum time. When the fuel injection time is less than the permissible minimum time, the electronic control device limits the lowest value of the feedback correction value to the safeguard value. As a result, the actual air-fuel ratio is prevented from being rich.

Abstract: Either associated process control or discrete process control is selected for valve timing control according to the engine operation state. Under the associated process control, the target displacement angle INP of an intake camshaft (22) is computed according to the engine operation state, and the actual displacement angle INR of the camshaft (22) is brought closer to it. Further, based on the target valve overlap amount OVP computed according to the engine operation state and the actual displacement angle INR, the target displacement angle EXP of an exhaust camshaft (23) is computed, and the actual displacement angle EXR of the camshaft (23) is brought closer to it. Under the discrete process control, the target displacement angles INP, EXP are computed according to the engine operation state, and the actual displacement angles INR, EXR are brought closer to them.

Abstract: Either associated process control or discrete process control is selected for valve timing control according to the engine operation state. Under the associated process control, the target displacement angle INP of an intake camshaft (22) is computed according to the engine operation state, and the actual displacement angle INR of the camshaft (22) is brought closer to it. Further, based on the target valve overlap amount OVP computed according to the engine operation state and the actual displacement angle INR, the target displacement angle EXP of an exhaust camshaft (23) is computed, and the actual displacement angle EXR of the camshaft (23) is brought closer to it. Under the discrete process control, the target displacement angles INP, EXP are computed according to the engine operation state, and the actual displacement angles INR, EXR are brought closer to them.

Abstract: A controller for a lock mechanism of an engine valve that readily performs unlocking. A VVT changes the rotational phase of a camshaft relative to a pulley in accordance with the difference between the hydraulic pressure of an advance pressure chamber and the hydraulic pressure of a delay pressure chamber to vary the valve timing. The hydraulic pressure difference is set by a variable command value. A lock mechanism engages a lock pin with a lock hole when the rotational phase of the camshaft matches a lock phase. The VVT enters the most easily unlocking hydraulic pressure state when the command value is set at an unlocking command value. An ECU gradually increases the command value from a lower limit value to the unlocking command value and then to the upper limit value to unlock relative rotation of the camshaft.

Abstract: A controller for controlling a valve timing of an engine that calculates a duty correction value using an arithmetic expression reflecting a physical model, which is associated with torque applied to an exhaust valve camshaft, a spring force exerted by an advancing spring for varying a rotational phase of the exhaust valve camshaft, and hydraulic pressure of operating oil. When the coolant temperature is lower than 80° C., the controller sets the duty correction value to zero. The duty correction value reflecting all the fluctuation factors of the engine is easily obtained without using a map requiring a large amount of data.