Abstract: An intake-air temperature controlling device for an engine is provided, which includes an engine body, an intake passage, an air intake part, an intake air temperature adjuster configured to adjust air temperature taken in through the air intake part to the passage, and a controller. An operating range in which the CI combustion is performed has a lean operating range in which A/F of mixture gas formed inside the cylinder, or G/F that is a relationship between the total weight G of gas inside the cylinder and a weight F of fuel fed to the cylinder is relatively low, and a rich operating range in which the A/F or G/F is relatively high. When the engine is in the lean operating range, the controller outputs a control signal to the intake air temperature adjuster so that the air temperature is increased, as compared in the rich operating range.

Abstract: A method for controlling an internal combustion engine is provided, which includes defining a first area in which the engine operates in a stoichiometric combustion mode and a second area in which the engine operates in a lean combustion mode, on an operation map defined by the engine load and speed, and causing a controller to determine that an operation point on the operation map shifts from the first area to the second area based on signals from an accelerator opening sensor and a crank angle sensor, predict a length of time that the operation point stays in the second area, switch a combustion mode to the lean combustion mode when the predicted time is longer than a given period of time, and maintain the stoichiometric combustion mode when the predicted time is shorter than the given period of time.

Abstract: A method for controlling an internal combustion engine is provided, which includes defining a first area in which the engine operates in a stoichiometric combustion mode and a second area in which the engine operates in a lean combustion mode, on an operation map defined by the engine load and speed, and causing a controller to determine that an operation point on the operation map shifts from the first area to the second area based on signals from an accelerator opening sensor and a crank angle sensor, predict a length of time that the operation point stays in the second area, switch a combustion mode to the lean combustion mode when the predicted time is longer than a given period of time, and maintain the stoichiometric combustion mode when the predicted time is shorter than the given period of time.

Abstract: An intake-air temperature controlling device for an engine is provided, which includes an engine body, an intake passage, an air intake part, an intake air temperature adjuster configured to adjust air temperature taken in through the air intake part to the passage, and a controller. An operating range in which the CI combustion is performed has a lean operating range in which A/F of mixture gas formed inside the cylinder, or G/F that is a relationship between the total weight G of gas inside the cylinder and a weight F of fuel fed to the cylinder is relatively low, and a rich operating range in which the A/F or G/F is relatively high. When the engine is in the lean operating range, the controller outputs a control signal to the intake air temperature adjuster so that the air temperature is increased, as compared in the rich operating range.