Abstract: An engine system includes a combustion chamber including a cylinder formed in an engine and a piston configured to reciprocate inside the cylinder, a spark plug disposed in a ceiling part of the combustion chamber, and a water injection device configured to inject water into the combustion chamber through a plurality of nozzle holes facing the inside of the combustion chamber. The piston has a cavity in an upper surface thereof. The water injection device injects water into the cavity in a compression stroke at a timing when an extension of axes of at least some of the nozzle holes intersects the cavity. The cavity has a bottom part where the water injected by the water injection device collides, and a raising part configured to raise the water spreading along the bottom part toward the water injection device.

Abstract: An engine system is provided, which includes an engine configured to generate a motive force for a vehicle by combusting a mixture gas of fuel and intake air, a water injector configured to inject heated water into a combustion chamber of the engine, and a controller configured to control the water injector to inject the water into the combustion chamber during an expansion stroke of the engine. The controller acquires a demanded engine load of the engine, and controls the water injector to increase an amount of water injection when the demanded engine load is within a first-load range, compared to when the demanded engine load is within a second-load range where the engine load is higher than in the first-load range.

Abstract: An engine system is provided, which includes an engine configured to generate a motive force for a vehicle by combusting a mixture gas of fuel and intake air, a water injector configured to inject heated water into a combustion chamber of the engine, and a controller configured to control the water injector to inject the water into the combustion chamber during an expansion stroke of the engine. The controller acquires a demanded engine load of the engine, and controls the water injector to retard a start timing of the water injection when the demanded engine load is within a first-load range, compared to when the demanded engine load is within a second-load range where the engine load is lower than in the first-load range.

Abstract: An engine system includes an engine, a water injection device that injects heated water into a combustion chamber, an accelerator position sensor that detects the accelerator position, and a controller that controls the water injection device so as to inject water into the combustion chamber during a compression stroke. The controller obtains a requested torque to be applied to the vehicle based on the accelerator position, obtains the requested engine load that is the load of the engine corresponding to the requested torque, and controls the water injection device so as to make the water injection amount when the requested engine load is in a first load region smaller than the water injection amount when the requested engine load is in a second load region in which the requested engine load is smaller than in the first load region.

Abstract: A structure of a combustion chamber applied to an engine provided with a piston that reciprocates inside a cylinder, and a fuel supply system that supplies fuel to the combustion chamber defined by the cylinder and the piston, mixture gas of fuel from the fuel supply system and air combusting inside the combustion chamber, is provided. The structure includes a first heat insulating layer covering at least a part of a combustion chamber wall surface defining the combustion chamber and made of a material with a lower thermal conductivity than the combustion chamber wall surface, and a second heat insulating layer covering the first heat insulating layer and facing toward the combustion chamber, a thermal diffusivity of the second heat insulating layer being larger than the thermal diffusivity of the first heat insulating layer. The second heat insulating layer has a thickness less than the first heat insulating layer.

Abstract: An engine system includes a combustion chamber including a cylinder formed in an engine and a piston configured to reciprocate inside the cylinder, a spark plug disposed in a ceiling part of the combustion chamber, and a water injection device configured to inject water into the combustion chamber through a plurality of nozzle holes facing the inside of the combustion chamber. The piston has a cavity in an upper surface thereof. The water injection device injects water into the cavity in a compression stroke at a timing when an extension of axes of at least some of the nozzle holes intersects the cavity. The cavity has a bottom part where the water injected by the water injection device collides, and a raising part configured to raise the water spreading along the bottom part toward the water injection device.