Abstract: When it is detected in a fuel supply device for a flexible-fuel internal combustion engine that a refueling operation has been performed for a fuel tank, a return suppression process in which fuel in a delivery pipe is prohibited from returning to the fuel tank through a high-pressure return passage is executed until a concentration learning process is started. After the concentration learning process is started, a compulsory return process in which fuel in the delivery pipe is compulsorily returned to the fuel tank through the high-pressure return passage is executed.

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: When it is detected in a fuel supply device for a flexible-fuel internal combustion engine that a refueling operation has been performed for a fuel tank, a return suppression process in which fuel in a delivery pipe is prohibited from returning to the fuel tank through a high-pressure return passage is executed until a concentration learning process is started. After the concentration learning process is started, a compulsory return process in which fuel in the delivery pipe is compulsorily returned to the fuel tank through the high-pressure return passage is executed.

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: A requested injection amount of fuel necessary during ignition cut-off at the time of start at an extremely low temperature is calculated (step ST2), injection start timing and injection end timing between which wetting of a spark plug by fuel is less likely are set (step ST3), and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount (step ST4). The injection start timing and the injection end timing are thus restricted to timings between which plug wetting is less likely, and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount, so that wetting of the spark plug by fuel at the extremely low temperature can be avoided even in an in-cylinder direct-injection engine.

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 requested injection amount of fuel necessary during ignition cut-off at the time of start at an extremely low temperature is calculated (step ST2), injection start timing and injection end timing between which wetting of a spark plug by fuel is less likely are set (step ST3), and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount (step ST4). The injection start timing and the injection end timing are thus restricted to timings between which plug wetting is less likely, and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount, so that wetting of the spark plug by fuel at the extremely low temperature can be avoided even in an in-cylinder direct-injection engine.

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: 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 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: In an internal combustion engine to which an air pressure actuation mechanism such as a variable vibration isolating support device is installed side by side, the engine speed at the time of idling is made to suitably converge on the target idling speed.

Abstract: Disclosed is an air-fuel ratio control apparatus, which controls the air-fuel ratio of a flammable air-fuel mixture to be supplied to an engine. This control apparatus controls the air-fuel ratio taking into account that fuel vapor produced in a fuel tank is added to the air-fuel mixture. The fuel vapor produced in the fuel tank is purged into the intake passage of the engine through a canister. An electronic control unit (ECU) controls the amount of fuel to be injected from each injector such that the air-fuel ratio of the air-fuel mixture matches a target air-fuel ratio. At the time the fuel vapor is purged, the ECU learns the density of fuel to be purged based on the detected value of an oxygen sensor. Based on this learned value, the ECU compensates the amount of fuel to be injected from each injector.