Abstract: An engine controlling method is provided, which includes, during motoring of the engine, outputting, by an in-cylinder pressure sensor, to a controller a signal indicative of a reference pressure corresponding to a pressure change after an intake valve of a cylinder of the engine is closed when not performing fuel injection, and then injecting, by an injector, fuel for analysis into the cylinder at a specific timing after the intake valve is closed. The method includes, by the controller, acquiring a crank angle period from the intake valve close timing, through the fuel injection, to a timing of the in-cylinder pressure reaching the reference pressure based on signals from the in-cylinder pressure sensor and a crank angle sensor, and determining a property of the injected fuel by comparing the acquired crank angle period with that of a standard fuel based on stored information on a property of the standard fuel.

Abstract: A method of controlling an engine is provided, which includes, during motoring of the engine, injecting, by an injector, fuel for analysis into a cylinder of the engine at a specific timing after an intake valve of the cylinder is closed. The method includes acquiring, by a controller, a crank angle period from a start timing of the fuel injection to a timing of a pressure inside the cylinder reaching a reference pressure, in response to signals of a crank angle sensor and an in-cylinder pressure sensor. The method includes determining, by the controller, a property of the fuel injected by the injector by comparing the acquired crank angle period with a reference crank angle period, the reference crank angle period being from an injection start timing when a standard fuel is injected into the cylinder to a timing of the pressure inside the cylinder reaching the reference pressure.

Abstract: An engine controlling method is provided, which includes, during motoring of the engine, outputting, by an in-cylinder pressure sensor, to a controller a signal indicative of a reference pressure corresponding to a pressure change after an intake valve of a cylinder of the engine is closed when not performing fuel injection, and then injecting, by an injector, fuel for analysis into the cylinder at a specific timing after the intake valve is closed. The method includes, by the controller, acquiring a crank angle period from the intake valve close timing, through the fuel injection, to a timing of the in-cylinder pressure reaching the reference pressure based on signals from the in-cylinder pressure sensor and a crank angle sensor, and determining a property of the injected fuel by comparing the acquired crank angle period with that of a standard fuel based on stored information on a property of the standard fuel.

Abstract: A method of controlling an engine is provided, which includes the steps of, during motoring of the engine, injecting, by an injector, fuel for analysis into a cylinder at a specific timing after an intake valve of the cylinder of the engine is closed, outputting to a controller, by an in-cylinder pressure sensor, a signal corresponding to a pressure inside the cylinder at least at a timing when a specific crank angle period has passed from the fuel injection timing, and determining, by the controller, a property of the fuel injected by the injector, by comparing a pressure value measured by the in-cylinder pressure sensor with a reference pressure value inside the cylinder measured at a timing when the specific crank angle period has passed after a standard fuel is injected into the cylinder at the specific timing.

Abstract: A method of controlling an engine is provided, the method including the steps of injecting main fuel by a fuel injector during an intake stroke or a compression stroke, providing a mixture gas containing fuel and air inside a cylinder, applying by an ignition device a high voltage between electrodes of a spark plug at a timing when the mixture gas is not ignited, detecting a parameter related to a current value of an electric-discharge channel generated between the electrodes, determining whether the detected parameter is within a range between a first threshold and a second threshold to determine a flowing state of a vortex inside the cylinder, injecting supplemental fuel by the fuel injector after the main fuel injection when the parameter is determined to be outside the range, and igniting the mixture gas by the ignition device using the spark plug after the supplemental fuel injection.

Abstract: A method of controlling an engine is provided, which includes the steps of injecting main fuel by a fuel injector during an intake stroke or a compression stroke, providing a mixture gas containing fuel and air inside a cylinder, applying by an ignition device a high voltage between electrodes of a spark plug at a timing when the mixture gas is not ignited, detecting a parameter related to a current value of an electric-discharge channel generated between the electrodes, determining by a controller whether the detected parameter is within a range between a first threshold and a second threshold to determine a flowing state of a vortex inside the cylinder, operating the spark plug to carry out a supplemental ignition when the parameter is determined to be outside the range, and igniting the mixture gas by operation of the spark plug after the supplemental ignition.

Abstract: A method of controlling an engine is provided, the method including the steps of injecting main fuel by a fuel injector during an intake stroke or a compression stroke, providing a mixture gas containing fuel and air inside a cylinder, applying by an ignition device a high voltage between electrodes of a spark plug at a timing when the mixture gas is not ignited, detecting a parameter related to a current value of an electric-discharge channel generated between the electrodes, determining whether the detected parameter is within a range between a first threshold and a second threshold to determine a flowing state of a vortex inside the cylinder, injecting supplemental fuel by the fuel injector after the main fuel injection when the parameter is determined to be outside the range, and igniting the mixture gas by the ignition device using the spark plug after the supplemental fuel injection.

Abstract: A combustion chamber structure for an engine includes a combustion chamber that is defined by a cylinder block, a cylinder head, and a piston. The cylinder head includes: a head body that has a lower surface opposing the combustion chamber; and a coat layer that covers the lower surface. The coat layer includes: a heat-insulating layer that is arranged in a region, which opposes a cavity, in the lower surface and has a lower thermal conductivity than the head body; a heat-shielding layer that is arranged to cover the lower surface and has a lower thermal conductivity than the head body and the heat-insulating layer; and a heat diffusion layer that is arranged between the heat-insulating layer and the heat-shielding layer and has a higher thermal conductivity. The heat diffusion layer includes a side end edge and an extending portion, each of which abuts the head body.

Abstract: An engine includes an output shaft, a cylinder block, a cylinder head, a cap portion, and head bolts. The cylinder block, the cylinder head, and the cap portion are fastened together with the head bolts. The cylinder block includes a cylinder portion and a plurality of output shaft supporting portions. When an outer wall face of at least one of the plurality of output shaft supporting portions is viewed along an output shaft axial direction, the outer wall face includes a first rib diagonally extending from a supporting portion of the output shaft toward one of two head bolt holes.

Abstract: A combustion chamber structure for an engine includes a combustion chamber that is defined by a cylinder block, a cylinder head, and a piston. The cylinder head includes: a head body that has a lower surface opposing the combustion chamber; and a coat layer that covers the lower surface. The coat layer includes: a heat-insulating layer that is arranged in a region, which opposes a cavity, in the lower surface and has a lower thermal conductivity than the head body; a heat-shielding layer that is arranged to cover the lower surface and has a lower thermal conductivity than the head body and the heat-insulating layer; and a heat diffusion layer that is arranged between the heat-insulating layer and the heat-shielding layer and has a higher thermal conductivity. The heat diffusion layer includes a side end edge and an extending portion, each of which abuts the head body.

Abstract: A combustion chamber is defined by a cylinder block, a cylinder head, and a piston. The cylinder block includes a block body that has a cylinder inner wall covered by a coat layer. The coat layer includes: a heat-shielding layer that covers an upper end of the cylinder inner wall, a piston ring not slidingly contacting the upper end; a heat-insulating layer arranged on a back side of the heat-shielding layer; and a heat diffusion layer arranged between the heat-insulating layer and the heat-shielding layer. Regarding thermal conductivity, the heat-insulating layer is lower than the block body, the heat-shielding layer is lower than the block body and the heat-insulating layer, and the heat diffusion layer is higher than the heat-insulating layer and the heat-shielding layer. The heat diffusion layer includes a side end edge and an extending portion, each of which abuts the block body.

Abstract: A combustion-chamber structure of an engine comprises a combustion chamber which is partitioned by a cylinder block, a cylinder head, a piston, an intake valve, and an exhaust valve. The intake valve (exhaust valve) comprises an intake valve body including an umbrella part having a valve head and a valve face, a heat-insulation layer provided at the valve head and having smaller heat conductivity than the valve body, a heat-barrier layer provided to cover the valve head with the heat-insulation layer and having smaller heat conductivity than the valve body and the heat-insulation layer, and a heat-diffusion layer provided between the heat-insulation layer and the heat-barrier layer and having larger heat conductivity than the heat-insulation layer and the heat-barrier layer. The heat-diffusion layer comprises a contact portion which contacts with the cylinder head when the intake valve is closed.

Abstract: An engine includes an output shaft, a cylinder head, a cylinder block, and a plurality of head bolts. The cylinder block includes three or more cylinder parts, a plurality of connecting portions, a plurality of output shaft supporting parts, and a plurality of head bolt holes. A side wall face of at least one cylinder part includes a first rib. The first rib diagonally extends from the connecting portion toward a head bolt hole base.

Abstract: A combustion-chamber structure of an engine comprises a combustion chamber which is partitioned by a cylinder block, a cylinder head, and a piston. The piston includes a piston body having an upper surface facing the combustion chamber, a heat-insulation layer provided at least in a central area, in a radial direction, of the upper surface and having smaller heat conductivity than the piston body, a heat-barrier layer provided to cover the upper surface and having smaller heat conductivity than the piston body and the heat-insulation layer, and a heat-diffusion layer provided between the heat-insulation layer and the heat-barrier layer and having larger heat conductivity than the heat-insulation layer and the heat-barrier layer. The heat-diffusion layer comprises a side end edge and an extension portion which contact with the piston body.

Abstract: An engine includes an output shaft, a cylinder block, a cylinder head, a cap portion, and head bolts. The cylinder block, the cylinder head, and the cap portion are fastened together with the head bolts. The cylinder block includes a cylinder portion and a plurality of output shaft supporting portions. When an outer wall face of at least one of the plurality of output shaft supporting portions is viewed along an output shaft axial direction, the outer wall face includes a first rib diagonally extending from a supporting portion of the output shaft toward one of two head bolt holes.

Abstract: A cylinder block includes a body part where a cylinder is formed, an outer wall part made of fiber reinforced resin and surrounding an outer circumference of the body part, and a metal member attached to the outer wall part. The outer wall part is comprised of an inner layer surrounding the outer circumference of the body part, and an outer layer surrounding an outer circumference of the inner layer. A density of reinforcing fiber contained in the outer layer is higher than a density of reinforcing fiber contained in the inner layer. The metal member is attached to the outer wall part so as to contact the outer layer. The reinforcing fiber contained in the outer layer has an electric insulating property.

Abstract: A cylinder block includes a body part where a cylinder is formed, an outer wall part made of fiber reinforced resin and surrounding an outer circumference of the body part, and a metal member attached to the outer wall part. The outer wall part is comprised of an inner layer surrounding the outer circumference of the body part, and an outer layer surrounding an outer circumference of the inner layer. A density of reinforcing fiber contained in the outer layer is higher than a density of reinforcing fiber contained in the inner layer. The metal member is attached to the outer wall part so as to contact the outer layer. The reinforcing fiber contained in the outer layer has an electric insulating property.

Abstract: A cylinder block includes a metal body part having a cylinder, and an outer wall part made of fiber reinforced resin, surrounding an outer circumference of the body part. A part of the outer wall part at BDC side in a cylinder axis direction contacts a bottom wall forming part. The outer wall part is comprised of an inner layer surrounding the outer circumference of the body part, and an outer layer surrounding an outer circumference of the inner layer. A density of reinforcing fiber contained in the outer layer is higher than that in the inner layer. A thickness of a part of the inner layer at BDC side in the cylinder axis direction is greater than that of the TDC-side inner layer. A thickness of a part of the outer layer at TDC side in the cylinder axis direction is greater than that of the BDC-side outer layer.

Abstract: An engine includes an output shaft, a cylinder head, a cylinder block, and a plurality of head bolts. The cylinder block includes three or more cylinder parts, a plurality of connecting portions, a plurality of output shaft supporting parts, and a plurality of head bolt holes. A side wall face of at least one cylinder part includes a first rib. The first rib diagonally extends from the connecting portion toward a head bolt hole base.

Abstract: A direct injection engine includes a fuel injection valve configured to inject fuel into a cylinder, a water injection valve configured to inject water into the cylinder, and a valve variable mechanism configured to change an operation timing of each of an intake valve and an exhaust valve. During an operation in a low load range, a negative overlap period when both of the intake valve and the exhaust valve are closed across an exhaust top dead center is formed by the valve variable mechanism, and fuel is injected from the fuel injection valve and water is injected from the water injection valve respectively during the negative overlap period. This causes a steam reforming reaction such that at least a part of injected fuel and injected water turns to hydrogen and carbon monoxide within the cylinder during the negative overlap period.