The present invention suppresses leakage of combustion gas from a contact surface. A cylinder head (20) is attached to a cylinder block. The surface (26) of the side of the cylinder head (20) that is attached to the cylinder block includes a first region (AH1) and a second region (AH2) that has higher hardness than the first region (AH1).

An internal combustion engine and a head gasket are provided. The internal combustion engine includes a block having at least one cylinder, a head joined to the block at a head interface, a cooling fluid circulation passage extending at least partially through the head and the block and having a first portion disposed in the head and a second portion disposed in the block, a head gasket having a plate extending across the head interface and separating the first portion of the cooling fluid circulation passage from the second portion of the cooling fluid circulation passage, and a plurality of orifices extending through the plate. The plurality of orifices is aligned with the cooling fluid circulation passage and is configured to control a flow of cooling fluid circulating between the first portion of the cooling fluid circulation passage and the second portion of the cooling fluid circulation passage.

A leak-proof sealing system is provided for sealing combustion chambers of an automotive engine. The system comprises a head gasket compressed between an engine block and a cylinder head, the head gasket comprising a gasket plate, a plurality of circular combustion apertures positioned on the gasket plate, the plurality of circular combustion apertures configured to register with a plurality of cylinder bore openings of the engine block, a plurality of bolt apertures distributed on the gasket plate, the plurality of bolt apertures alternating with the plurality of circular combustion apertures, and a plurality of wire rings, each wire ring extending circumferentially around a corresponding circular combustion aperture of the plurality of circular combustion apertures, where a surface of each wire ring includes a selective metal coating on sections of the wire ring spanning between two consecutive bolt apertures of the plurality of bolt apertures, and wherein sections of the wire ring located closer to the plurality of bolt apertures are devoid of metal coating. In one example, the system helps increase stress locally and reduces fatigue lift motion, thereby improving sealing and engine durability.

Systems are provided for cooling a cylinder block via bore bridge cooling passages. In one example, a cylinder block with a bore bridge positioned between a first cylinder and a second cylinder, the cylinder block also including a coolant jacket at least partially surrounding the first cylinder and the second cylinder, has at least one cooling passage positioned within the bore bridge. An inlet of the at least one cooling passage has a larger area than an outlet of the at least one cooling passage and at least a portion of the at least one cooling passage has a non-cylindrical geometry formed by a lost core.

A cylinder head cover for covering a cylinder head of an internal combustion engine having at least one first sealing surface via which the cylinder head cover can be tightly connected to an associated second sealing surface on the cylinder head, the cylinder head cover may include at least one first reference surface configured for unambiguous position-fixing on an associated second reference surface of the cylinder head. The at least one first reference surface and the at least one first sealing surface may be formed separately from one another.

A cylinder head (1) disclosed herein includes a cylinder head main body (10) having an intake port (3) communicating with a combustion chamber (2) of an engine; and an insulation member (20) being arranged at an inner side of the intake port (3), made of resin, and formed into an annular shape. A step part (14) is formed at a downstream side of the insulation member (20) in a flow direction of intake air in the intake port (3) such that the intake port (3) has a cross section perpendicular to the flow direction at the downstream side smaller than a cross section perpendicular to the flow direction at an upstream side of the flow direction; and an annular seal member (21) that seals a space between the insulation member (20) and the step part (14) is arranged between the insulation member (20) and the step part (14).

Systems are provided for cooling a cylinder block via bore bridge cooling passages. In one example, a cylinder block with a bore bridge positioned between a first cylinder and a second cylinder, the cylinder block also including a coolant jacket at least partially surrounding the first cylinder and the second cylinder, has at least one cooling passage positioned within the bore bridge. An inlet of the at least one cooling passage has a larger area than an outlet of the at least one cooling passage and at least a portion of the at least one cooling passage has a non-cylindrical geometry formed by a lost core.

A cylindrical part capable of supporting an ignition-coil-integrated plug cap is formed on a head cover so as to correspond to a plug hole of a cylinder head. The cylindrical part is formed by fitting and fixing a pipe material to a mounting hole part formed in the head cover, the mounting hole part facing the plug hole.

An internal combustion engine and a head gasket are provided. The internal combustion engine includes a block having at least one cylinder, a head joined to the block at a head interface, a cooling fluid circulation passage extending at least partially through the head and the block and having a first portion disposed in the head and a second portion disposed in the block, a head gasket having a plate extending across the head interface and separating the first portion of the cooling fluid circulation passage from the second portion of the cooling fluid circulation passage, and a plurality of orifices extending through the plate. The plurality of orifices is aligned with the cooling fluid circulation passage and is configured to control a flow of cooling fluid circulating between the first portion of the cooling fluid circulation passage and the second portion of the cooling fluid circulation passage.

A gasket has a gasket member including a metal sheet and rubber layers put over both faces of the metal sheet. The gasket member includes a seal bead, at least one insertion hole, and at least one dummy bead. The seal bead is a part protruding from a lower face of the gasket member side toward an upper face of the gasket member side. The insertion hole is a through hole into which a fastener is inserted. The dummy bead is a part protruding from the lower face of the gasket member side toward the upper face of the gasket member side. The dummy bead extends around the insertion hole. A resonance frequency of the gasket member is adjusted by a length of the dummy bead in a direction of extension.