This liquid injection nozzle atomizes and sprays liquid, while reducing loss of kinetic energy, thereby promoting mixing between the liquid and a gas and thus promoting the reaction between the liquid and the gas. In the liquid injection nozzle, a plurality of distal end tips each having an injection hole are provided on a distal end portion of a nozzle body. Each distal end tip has a conical swirling flow chamber. A communication thin hole is formed in the distal end portion. The communication thin hole extends from a hollow chamber to the conical swirling flow chamber of the distal end tip. When the valve needle is lifted, liquid flows through the communication thin hole into the swirling flow chamber in a tangential direction and generates a vortex flow, and the vortex flow is sprayed from the injection hole.

An object of the invention is to provide an internal combustion engine that suppresses a blow-by phenomenon in an overlap period, while allowing for formation of a favorable swirl flow in a combustion chamber. In the internal combustion engine, a housing space is formed in an opening of an exhaust port to the combustion chamber to be more recessed in a cylinder head than an exhaust port-side ceiling surface. A bevel portion of an exhaust valve is placed in the housing space in a valve closed state of the exhaust valve. A valve contact surface is formed on an inner wall surface of the housing space. With regard to an effective passage width of an effective passage that is defined as a linear virtual passage extended from the combustion chamber through the housing space to inside of the exhaust port in a section extended from an intake port side to a bore wall surface side of an exhaust port side, the housing space is formed such that the effective passage width in any location in an intake side space is made smaller than the effective passage width in a corresponding location in an exhaust side space in a slight lifting state of the exhaust valve.

An internal-combustion engine includes a cylinder, a piston, a spark plug, and a fuel injection valve. The piston includes a top surface and a cavity provided in the top surface. The cavity includes a bottom surface, a vertical wall, a first sidewall, and a second sidewall. The fuel injection valve includes a plurality of injection ports from which a plurality of fuel mists are to be obliquely injected toward the top surface of the piston in respectively different directions at a predetermined crank angle in a compression stroke. The cavity extends from a position close to a center of the piston toward the fuel injection valve when viewed from above the top surface of the piston. The first and second sidewalls extend toward the fuel injection valve when viewed from above the top surface of the piston.

An intake device of an engine having cylinders is provided. The intake device includes a cylinder head formed with two intake ports per cylinder, and a forced induction system. One of the two intake ports is designed to have a smaller passage cross-sectional area at a throat portion thereof than that of the other intake port, and to cause a strength of a tumble flow strength of intake air formed within a combustion chamber to be stronger when a flow of the intake air into the combustion chamber is assumed to be caused only from the one of the two intake ports, than only from the other intake port. A tumble ratio of the intake air flow within the combustion chamber is a predetermined value or greater when the intake air is forcibly induced and flows into the combustion chamber from the two intake ports.

With regard to an internal combustion engine having a tumble flow formed in a cylinder, an object of the invention is to intensify the tumble flow. There is provided an internal combustion engine having a pent-roof type combustion chamber. In a predetermined area in the vicinity of an opening of an intake port to a combustion chamber, an upper wall surface of the intake port is extended approximately linearly while being inclined to an intake port-side ceiling surface more downward than a normal direction of the intake port-side ceiling surface in a side view. In a partial area in the predetermined area of the intake port, a distance between lateral wall surfaces on a left side and on a right side of the intake port is gradually increased toward downstream in a top view.

With regard to an internal combustion engine having a tumble flow formed in a cylinder, an object of the invention is to intensify the tumble flow. There is provided an internal combustion engine having a pent-roof type combustion chamber. In a predetermined area in the vicinity of an opening of an intake port to a combustion chamber, an upper wall surface of the intake port is extended approximately linearly while being inclined to an intake port-side ceiling surface more downward than a normal direction of the intake port-side ceiling surface in a side view. In a partial area in the predetermined area of the intake port, a distance between lateral wall surfaces on a left side and on a right side of the intake port is gradually increased toward downstream in a top view.

A thermal insulation film is formed on a bottom surface of a cylinder head facing a top surface of a piston. The thermal insulation film in a region (a circumferential region) of a bottom surface of the cylinder head configuring a squish area in a circumferential edge of a cavity region is formed to be thinner than the thermal insulation film in a region (a cavity region) of the bottom surface of the cylinder head facing a cavity. The thermal insulation film in the circumferential region is polished, and surface roughness thereof is equal to or lower than 3 μm. The thermal insulation film in the cavity region is not polished, and surface roughness thereof is 3 to 8 μm on average.

An object is to enable stable diesel combustion in an internal combustion engine using a fuel having a relatively high self-ignition temperature. In the internal combustion engine, pre-injection and ignition of pre-spray fuel are performed, and thereafter main injection is performed to cause a portion of main-injected fuel to be burned by diffusion combustion. Injection ports of a fuel injection valve are provided in such a way that the quantity of the main injected fuel injected to a predetermined region defined by a predetermined angle equal to or smaller than 90 degrees about the fuel injection valve from the location of an ignition device in the direction of rotation of the swirl is relatively small.

An object of the invention is to reduce the amount of smoke generated and to improve the stability of diesel combustion in cases where an EGR apparatus is used in an internal combustion engine that performs diesel combustion using fuel having a relatively high self-ignition temperature. A control apparatus performs first injection at a first injection time during the compression stroke, causes spray guide combustion to occur, and starts to perform second injection at such a second injection time that causes combustion of injected fuel to be started by flame generated by the spray guide combustion, thereby causing self-ignition and diffusion combustion of fuel to occur. The apparatus changes the ratio of the first injected fuel quantity to the total fuel injection quantity and the ratio of the second injected fuel quantity to the total fuel injection quantity for the same total fuel injection quantity in one combustion cycle, based on the EGR rate in the intake air.

In an upstream portion from a valve connecting surface that is formed in an opening of an intake port to a combustion chamber, an upper wall surface of the intake port continues from an upstream side end of the valve connecting surface and extends substantially straight and diagonally with respect to a ceiling surface on the intake port side. In addition, a cross-sectional shape of the portion in the intake port in a direction perpendicular to an axial direction of the intake port is a flat shape with an axis in a transverse direction being a long axis.