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: 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: After initial combustion at the time of engine startup under very low temperature conditions, a fuel-injection start time point and a fuel-injection end time point are restricted to a period of time during which smoldering of an ignition plug is less prone to occur, to warm up the inside of a cylinder and increase engine speed. Thereafter, a fuel injection period is adjusted by gradually elongating it by reducing the restriction on the injection start time point and the injection end time point each time the engine speed exceeds a predetermined value in the course of the increase in the engine speed. In this way, the engines are made to reach a state where the engine can operate in a self-sustaining manner, before smoldering of the ignition plugs progresses after the initial combustion at the time of the engine startup under very low temperature conditions.

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: After initial combustion at the time if engine startup under very low temperature conditions, a fuel-injection start time point and a fuel-injection end time point are restricted to a period of time during which smoldering of an ignition plug is less prone to occur, to warm up the inside of a cylinder and increase engine speed. Thereafter, a fuel injection period is adjusted by gradually elongating it by reducing the restriction on the injection start time point and the injection end time point each time the engine speed exceeds a predetermined value in the course of the increase in the engine speed. In this way, the engines are made to reach a state where the engine can operate in a self-sustaining manner, before smoldering of the ignition plugs progresses after the initial combustion at the time of the engine startup under very low temperature conditions.

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.