A plural port intake manifold with outlets aligned along a common cylinder head plane and each intake port containing, a valve unit including a valve plate that is rotatable by a shaft along an axis of rotation recessed within an inner wall as well as a welded connection encircling each intake port upstream of the axis. The system may allow the use of a plate CMCV that can fully retract into the intake runner when not in use.

There is provided an internal combustion engine in which respective combustion states of cylinders can be uniformized with a simple configuration. A central axis (CL1) of a connecting part (7) of one of air supply ports (5) inclines with a predetermined inclination angle in a direction away from an air supply inlet (3) with respect to a y direction orthogonal to an x direction in which an air supply manifold 1 extends, and an inclination angle of the connecting part (7) of the one of the air supply ports (5) is larger than an inclination angle of the connecting part (7) of other air supply ports (5) located on a side closer to the air supply inlet (3) than the one of the air supply ports (5).

There is provided an internal combustion engine in which respective combustion states of cylinders can be uniformized with a simple configuration. A central axis (CL1) of a connecting part (7) of one of air supply ports (5) inclines with a predetermined inclination angle in a direction away from an air supply inlet (3) with respect to a y direction orthogonal to an x direction in which an air supply manifold 1 extends, and an inclination angle of the connecting part (7) of the one of the air supply ports (5) is larger than an inclination angle of the connecting part (7) of other air supply ports (5) located on a side closer to the air supply inlet (3) than the one of the air supply ports (5).

A uniflow scavenging two-cycle engine includes an scavenging port having a swirling guide portion that guides scavenging gas into a cylinder in a direction inclined with respect to a radial direction of the cylinder, and a center guide portion that is provided to be closer to a crank side of the cylinder than the swirling guide portion and guides the scavenging gas further toward the center side of the cylinder than the swirling guide portion. At least a part of the center guide portion faces a piston when the piston is positioned at bottom dead center during the high compression ratio mode, and the center guide portion and the piston do not face each other or an area of facing the piston is smaller than that during the high compression ratio mode when the piston is positioned at bottom dead center during the low compression ratio mode.

A uniflow scavenging two-cycle engine includes an scavenging port having a swirling guide portion that guides scavenging gas into a cylinder in a direction inclined with respect to a radial direction of the cylinder, and a center guide portion that is provided to be closer to a crank side of the cylinder than the swirling guide portion and guides the scavenging gas further toward the center side of the cylinder than the swirling guide portion. At least a part of the center guide portion faces a piston when the piston is positioned at bottom dead center during the high compression ratio mode, and the center guide portion and the piston do not face each other or an area of facing the piston is smaller than that during the high compression ratio mode when the piston is positioned at bottom dead center during the low compression ratio mode.

An engine has a cylinder head defining an intake port with a roof defining first and second valve guide bores upstream of first and second siamesed intake valve seats for a cylinder. The head has first and second asymmetric fairings extending outwardly from the roof and positioned directly upstream of respective bores. Each fairing has an inner wall intersecting an outer wall along an upstream edge and an inclined planar roof wall extending between the inner and outer walls. A method of forming the cylinder head and engine is also provided by milling the fairings from a roof preform formed with the intake port of the head.

When an amount of a backward tumble flow is smaller than an amount of a forward tumble flow, the intake-side valve recess is used as a first valve recess and the exhaust-side valve recess is used as a second valve recess. When the amount of the backward tumble flow is larger than the amount of the forward tumble flow, the exhaust-side valve recess is used as a first valve recess and the intake-side valve recess is used as a second valve recess. An inclination angle of the first valve recess is larger than an inclination angle of the second valve recess when comparing the inclination angle such that a height of the recess decreases gradually toward an inner side of a cross-section.

A combustion chamber for an opposed-piston engine has a rotationally skewed shape in a longitudinal section that is orthogonal to a chamber centerline, between diametrically-opposed openings of the combustion chamber through which fuel is injected. The rotationally skewed shape interacts with swirl to generate a tumble bulk charge air motion structure that increases turbulence.

Provided is an in-combustion chamber flow control device used in an engine having an intake passage connected to an intake opening formed in a ceiling surface of a combustion chamber, at an angle inclined with respect to a direction of an axis of a cylinder. This in-combustion chamber flow control device comprises a plasma actuator (28) disposed inside the combustion chamber (16). The plasma actuator comprises: a dielectric body (38) disposed along the ceiling surface (16a) of the combustion chamber, at a position closer to a center of the ceiling surface than the intake opening (18a); an exposed electrode (40) disposed on one side of the dielectric body facing the combustion chamber; and an embedded electrode (42) disposed on a side opposite to the exposed electrode across the dielectric body. The embedded electrode is disposed at a position closer to the intake opening than the exposed electrode.

An air intake duct includes an air intake duct body (11) which includes an air intake part (111) and a connecting part (112) connected with the air intake part (111). A first channel is formed inside the air intake part (111), a second channel intercommunicating with the first channel is formed inside the connecting part (112), one side of the connecting part (112) is provided with a connecting surface (112a) which inclines towards an axis of the air intake duct body (11), the connecting surface (112a) is inclined and extended from a connection joint of the connecting part (112) and the air intake part (111) to an end portion of the connecting part (112), and the first channel has a larger cross section area than the second channel.