An apparatus that controls a swirl ratio in a diesel engine for a motor vehicle includes a first intake port that directs a first airflow into a combustion chamber, and a second intake port that directs a second airflow into the combustion chamber. The first and second intake ports are arranged to direct the first airflow and the second airflow such that a desired swirl ratio is achieved in the combustion chamber.

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.

An engine provided with a combustion chamber includes a cylinder head in which a bulkhead is provided so as to extend toward the combustion chamber and an intake port is formed so as to bifurcate at the bulkhead, a bulkhead member that is provided with a partition plate intersecting the bulkhead and that divides the intake port into a first flow passage and a second flow passage with the partition plate provided between the first and second flow passages. The bulkhead of the cylinder head has a cutout formed and the partition plate of the bulkhead plate has an auxiliary wall that fills the cutout.

An intake device of an internal combustion engine includes a partition, a control valve, and a third passage. The partition divides an interior of an intake pipe that couples with a combustion chamber into a first passage and a second passage. The control valve is capable of opening and closing the first passage. The third passage opens at or near a coupling site between the partition and the intake pipe on an inner face of the second passage. The third passage is configured to be capable of sucking in at least a part of a boundary layer produced at or near the coupling site by a vapor flowing through the second passage in a state in which the control valve is working in a direction of closing the first passage.

An intake port structure has a sleeve disposed along an inner peripheral surface of an intake port of a cylinder head and made of a material having a thermal conductivity lower than a material of the cylinder head. When a cross-sectional area of an intake passage on an upstream side in an vicinity of a mating surface between the cylinder head and the intake passage toward the cylinder head is defined as a mating surface upstream area, and an intake port cross-sectional area of the intake port, which excludes the sleeve, on a downstream side in the vicinity is defined as a mating surface downstream area, the mating surface downstream area is greater than the mating surface upstream area, and the intake port cross-sectional area at a place where the sleeve is disposed in the intake port is gradually reduced from the mating surface toward a combustion chamber side.

An engine provided with a combustion chamber includes a cylinder head in which a bulkhead is provided so as to extend toward the combustion chamber and an intake port is formed so as to bifurcate at the bulkhead, a bulkhead member that is provided with a partition plate intersecting the bulkhead and that divides the intake port into a first flow passage and a second flow passage with the partition plate provided between the first and second flow passages. The bulkhead of the cylinder head has a cutout formed and the partition plate of the bulkhead plate has an auxiliary wall that fills the cutout.

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.

An intake apparatus for an engine is provided. The intake apparatus includes an intake manifold configured to draw intake air thereinto, a cylinder head having an intake port through which intake air drawn from the intake manifold is supplied into a cylinder of the engine and a flow control valve disposed in the intake manifold and configured to control a flow direction of intake air to be drawn from the intake manifold into the cylinder head to generate a circular flow in the intake air. A port plate is configured to reinforce the circular flow of intake air that is generated in the flow control valve and a plate support is coupled with the port plate and coupled between the intake manifold and the cylinder head to enable the port plate to be inserted into the intake port.

An air intake structure for a vehicle engine includes: a variable flap rotatably provided in an intake air passage so as to control a cross-sectional area of intake air flow; a port plate provided to a downstream of the variable flap, and generating displacement in cooperation with the variable flap; a driving unit supplying a driving force for generating displacement of both the variable flap and the port plate; and a controller determining a rotation angle of the variable flap in accordance with an operating range of an engine, and controlling the rotation angle of the variable flap by driving the driving unit.

A low-temperature cooling water channel formed in the internal combustion engine includes a water jacket that covers at least one portion of a wall surface of an intake port. The intake port has a cooled wall surface that is covered by the water jacket, and a non-cooled wall surface that is not covered by the water jacket. An airflow control valve is provided on an intake-air upstream side of the cooled wall surface. The airflow control valve is configured to be capable of changing a ratio between a flow rate of intake air that flows along the side of the cooled wall surface and a flow rate of intake air that flows along the side of the non-cooled wall surface. The airflow control valve is preferably configured as a tumble control valve (TCV).