An internal combustion engine for a motor vehicle has at least one cylinder for accommodating a piston and at least one pre-chamber spark plug allocated to the combustion chamber of the cylinder. The engine also has a pre-chamber, fluidically connected with the combustion chamber via several openings, in which at least one ignition spark is generable by the pre-chamber spark plug. At the induction stroke of the internal combustion engine, a rinsing of the pre-chamber with inlet gas including at least fuel and air occurs, so that, at the ignition point, an ignitable mixture of fuel and air is accommodated in the pre-chamber.

An internal combustion engine includes a plurality of cylinders, and these cylinders are divided into a first group where the air-fuel mixture is burned in the entire operating region and a second group where the air-fuel mixture is not burned in part of the operating region. The engine comprising: an intake opening opened and closed by an intake valve; an exhaust opening opened and closed by an exhaust valve; and a mask part having a wall surface extending along an outer edge of the intake opening toward the inside of the combustion chamber at an opposite side from the exhaust opening side. The mask part is configured so that a clearance from a passage surface of an edge part of the intake valve to the wall surface of the mask part is smaller at each cylinder of the first group than each cylinder of the second group.

An internal combustion engine includes an ignition plug and an electronic control unit. The electronic control unit is configured to: (i) execute a lean-burn operation in a first operation region, (ii) execute an operation in a second operation region at an air-fuel ratio lower than an air-fuel ratio during the lean-burn operation, and (iii) control a gas flow in a cylinder so that a ratio of a change in a gas flow speed around the ignition plug during ignition to a change in an engine rotation speed in a first engine rotation speed region within the first operation region is smaller than the ratio in a second engine rotation speed region within the second operation region.

A structure of a combustion chamber for an engine includes a crown surface of a piston, a combustion chamber ceiling surface, an injector and an ignition plug provided on the combustion chamber ceiling surface, and an intake opening and an exhaust opening opened in the combustion chamber ceiling surface. A side where the intake opening is opened is defined as an intake port side, and a side where the exhaust opening is opened is defined as an exhaust port side. An ignition portion of the ignition plug is disposed on the intake port side. The ignition plug is ignited at a timing after the piston passes a compression top dead center. The injector is disposed on the center portion, and is configured to inject fuel toward the exhaust port side. A cavity is provided on the crown surface. A reverse squish flow generation portion is provided in the combustion chamber.

A gasoline direct injection (GDI) engine may include: a cylinder block having a cylinder; a cylinder head having an intake port, an intake valve opening and closing the intake port, an exhaust port, and an exhaust valve opening and closing the exhaust port; a piston reciprocating in the cylinder; a combustion chamber defined by the cylinder head, the piston, and an inner wall surface of the cylinder; and a fuel injector injecting a fuel into the combustion chamber. In particular, the combustion chamber is divided into an intake side where the intake port and the intake valve are located, and an exhaust side where the exhaust port and the exhaust valve are located, and a nozzle of the fuel injector is mounted in the cylinder head toward the exhaust side.

A combustion chamber structure for an engine includes a combustion chamber where SI combustion by spark ignition and CI combustion by self-ignition are conducted. A crown surface includes a cavity recessed to have a bowl-shape, and a pair of raised portions. The cavity includes a bottom portion which is a lower region of the recessed part, the bottom portion having an outer circumferential edge which is circular in a top view. With a height of the raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a diameter of an outer circumferential edge of the bottom portion of the cavity being represented as D, H1/D as a ratio of the height H1 of the raised portion to the diameter D of the cavity is set to be in a range of 0.05 or more and 0.36 or less.

A combustion chamber structure for an engine includes a combustion chamber where SI combustion by spark ignition and CI combustion by self-ignition are conducted. A crown surface includes a cavity recessed to have a bowl-shape; a pair of first raised portions having a mound-shape along a pent roof shape; and a second raised portion provided to protrude at a position orthogonal to a ridge extending direction of the pair of first raised portions. With a height of the first raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a height of the second raised portion being represented as H2, H1/H2 as a ratio of the height H1 of the first raised portion to the height H2 of the second raised portion is set to be in a range of 1.92 or more and 2.75 or less.

A cylinder head of an engine is provided, which includes first and second intake ports that open to a common cylinder. The first intake port opens to the cylinder to generate a swirl flow. The second intake port has a tumble flow generating part configured to cause intake air to become a tumble flow in the same direction as the swirl flow. The tumble flow generating part includes a helical part having an inner wall surface curving on a centerline perpendicular to an opening surface of the second port and continuing from a first port side to the opening of the second intake port toward at an opposite side from the first port. The opening of the second intake port has an edge part having an opening angle with respect to the centerline of the second port, the opening angle being smaller at an upstream side of the swirl flow.

A hydrogen intake assembly for a hydrogen internal combustion engine characterized in that the hydrogen intake assembly includes at least one air intake manifold comprising an air intake pipe comprising at least one air inlet and air outlets, air intake runners comprising air inlets and air outlets, a spacer having a wall defining an inner chamber receiving a mixture of air, water and hydrogen and comprising air inlets and mixture outlets delivering said mixture, a water rail comprising at least one water inlet and water outlets, said water outlets being embedded in the wall of the spacer and a hydrogen rail comprising at least a hydrogen inlet and hydrogen outlets.

In an intake structure of an internal combustion engine, on an intake upstream side from a valve seat of an intake port, a convex portion is provided which protrudes to an inside of the intake port in a place near an outer circumferential portion of a cylinder chamber when viewed from an upper side of the cylinder chamber. The convex portion includes an upstream guide surface extending from an apex of the convex portion to the intake upstream side, and a downstream guide surface extending from the apex to an intake downstream side and including a curved surface recessed inside the convex portion at a middle portion thereof.