Described is an internal combustion engine, in particular including a dual-circuit water cooling system, including a crankcase and at least one inlet and/or outlet rail which is/are situated upstream from the crankcase and receives a coolant communicating with this crankcase, at least one coolant-conducting cylinder head, and at least one outlet and/or inlet rail downstream from the cylinder head receiving a coolant communicating with the cylinder head.

A water jacket structure includes: a lower water jacket that is provided inside a cylinder head installed at the top of a cylinder block; and an upper water jacket that communicates with the lower water jacket, and is provided on a side away from the cylinder block than the lower water jacket; wherein the lower water jacket includes, for each space between cylinders: a communication flow passage that communicates with the upper water jacket; and a reinforcing post formation part on which a reinforcing post is installed; wherein the reinforcing post formation part is located on a downstream side in a flowing direction of cooling water along a cylinder arrangement direction than the communication flow passage.

In a cylinder head according to an example of the present disclosure, a pair of intake ports communicating with the common combustion chamber are formed so that the wall thickness of the port walls on opposing sides is relatively small and the wall thickness of the port walls on reversing sides is relatively large. Herein, the opposing side is the side on which the port walls of the pair of the intake ports face each other. The reversing side is the side opposite to the opposing side. That is, the reversing side is the side on which the port walls of the pair of the intake ports face away from each other. An inter-ports flow path for flowing the cooling water is formed between the port walls on the opposing sides of the pair of the intake ports.

Methods and systems are provided for a water jacket diverter. In one example, the water jacket diverter may be formed by injection molding and includes features such as cut-outs, an inlet ledge, a continuous upper rail, and one or more fins. The water jacket diverter may increase coolant flow in an upper portion of the water jacket, thereby increasing a cooling efficiency at an upper region of a cylinder block.

Methods and systems are provided for a water jacket diverter. In one example, the water jacket diverter may be formed by injection molding and includes features such as cut-outs, an inlet ledge, a continuous upper rail, and one or more fins. The water jacket diverter may increase coolant flow in an upper portion of the water jacket, thereby increasing a cooling efficiency at an upper region of a cylinder block.

A head cover structured and arranged to cover at least part of a face of a cylinder head of an internal combustion engine is described. The head cover includes a chamber formation part structured and arranged to provide a chamber to restrain sound propagating through air from the cylinder head. The chamber formation part includes a partition part for partitioning the chamber from a space on a cylinder head side. The partition part has a convex part projecting into the chamber, and a through hole may be provided in the convex part that penetrates from the space on the cylinder head side to the chamber.

A head cover structured and arranged to cover at least part of a face of a cylinder head of an internal combustion engine is described. The head cover includes a chamber formation part structured and arranged to provide a chamber to restrain sound propagating through air from the cylinder head. The chamber formation part includes a partition part for partitioning the chamber from a space on a cylinder head side. The partition part has a convex part projecting into the chamber, and a through hole may be provided in the convex part that penetrates from the space on the cylinder head side to the chamber.

Components for reducing oil sticking on surfaces of an internal combustion engine are disclosed. The engine may include an engine block with a piston cylinder, a piston moveable in reciprocal motion within the piston cylinder, and a cylinder head mounted on the engine block. The engine block, the cylinder head, and the piston may define a combustion chamber. The engine may include an intake conduit mounted to the cylinder head, an intake valve port defined by the cylinder head, and an intake valve mounted in reciprocally movable fashion to the cylinder head for placing the intake valve port in fluid communication with the combustion chamber. The engine may include a first oleophobic coating provided on portions of the intake valve, and a valve seat insert secured to the cylinder head. The valve seat insert may define an oil passage in fluid communication with the intake valve port.

Components for reducing oil sticking on surfaces of an internal combustion engine are disclosed. The engine may include an engine block with a piston cylinder, a piston moveable in reciprocal motion within the piston cylinder, and a cylinder head mounted on the engine block. The engine block, the cylinder head, and the piston may define a combustion chamber. The engine may include an intake conduit mounted to the cylinder head, an intake valve port defined by the cylinder head, and an intake valve mounted in reciprocally movable fashion to the cylinder head for placing the intake valve port in fluid communication with the combustion chamber. The engine may include a first oleophobic coating provided on portions of the intake valve, and a valve seat insert secured to the cylinder head. The valve seat insert may define an oil passage in fluid communication with the intake valve port.

An internal combustion engine comprising at least a crank case, which houses a cylinder, and a cylinder head, which is adapted to be coupled to the crank case, and a liquid cooling circuit, wherein the liquid cooling circuit comprises at least one inlet aperture and at least one outlet aperture, a lower cooling chamber housed in said cylinder head in a position adjacent to a flame deck of said cylinder head; an upper cooling chamber housed in said cylinder head above said lower chamber, so that said lower chamber is sandwiched between said upper chamber and said flame deck; wherein said inlet aperture is provided in said upper or lower chamber and said outlet aperture is provided in said lower or upper chamber, on a same side of the internal combustion engine, so that the cooling liquid runs in a substantially U-shaped path moving between said upper chamber and said lower chamber, transversely relative to a crankshaft of said engine.