A cylinder head assembly includes a cylinder head casting, and an injector sleeve within an injector bore in the cylinder head casting. The injector sleeve includes a first sleeve end, and an injector clamping surface formed by an inner sleeve surface adjacent to a cylindrical second sleeve end. The injector sleeve further includes a sleeve clamping surface in contact with an upward facing middle deck surface of the cylinder head casting, and a reaction wall extending between the injector clamping surface and the sleeve clamping surface to transfer an injector clamping load to the upward facing middle deck surface.

A guiding portion of an intake valve head includes a specific tangent line, which, when the intake valve is in a fully open state, intersects with at least one selected from an ignition plug and a closed exhaust valve. A line segment that agrees with a tangent line contacting the guiding portion and extends from a contact point of the tangent line with the guiding portion to an intersection point of the tangent line with a central axis of the head is defined as a first line segment, a line segment that agrees with the central axis and extends from the intersection point toward the intake passage is defined as a second line segment, and an angle formed by the first second line segments is defined as a specific angle. The tangent line that minimizes the specific angle is the specific tangent line.

An internal combustion engine includes a cylinder head including a first valve lifter hole, a first camshaft rotatably supported on the cylinder head, a first valve lifter inserted in the first valve lifter hole, a first valve spring that biases the first valve lifter toward the first cam of the first camshaft, and an oil supply passage having a first oil supply port formed on the inner circumferential surface of the first valve lifter hole and a first passage connected to the first oil supply port. An upper end of the first oil supply port is located upward relative to the upper surface of the first valve lifter when the first valve lifter is in the lower position. A lower end of the first oil supply port is located downward relative to the upper surface of the first valve lifter when the first valve lifter is in the upper position.

In an engine (1), an ignition plug (22) is arranged between a first intake port (6) and a second intake port (7). In a case where a downstream end portion (71) of the second intake port (7) is divided into a first intake port (6) side and an opposite first intake port (6) side, an inner wall surface (71a) of an opposite first intake port (6) side portion extends in a direction toward the first intake port (6) as extending from an upstream side to a downstream side of the second intake port (7).

An internal combustion engine includes a cylinder head including a first valve lifter hole, a first camshaft rotatably supported on the cylinder head, a first valve lifter inserted in the first valve lifter hole, a first valve spring that biases the first valve lifter toward the first cam of the first camshaft, and an oil supply passage having a first oil supply port formed on the inner circumferential surface of the first valve lifter hole and a first passage connected to the first oil supply port. An upper end of the first oil supply port is located upward relative to the upper surface of the first valve lifter when the first valve lifter is in the lower position. A lower end of the first oil supply port is located downward relative to the upper surface of the first valve lifter when the first valve lifter is in the upper position.

In an engine (1), when an intake valve (16) opens, a downstream end portion (61) of a first intake port (6) extends to direct to between a shade back (162a) positioned on a cylinder axis (C) side with respect to a valve stem (161) and a ceiling surface (51) facing the shade back (162a). As viewed in a section perpendicular to a direction perpendicular to an intake air flow direction, a second intake port side inner wall surface (61a) at the downstream end portion (61) of the first intake port (6) curves apart from a second intake port (7) in a direction from an exhaust side to an intake side as compared to the shape of an opposite second intake port side inner wall surface (61b) mirror-reversed to a second intake port (7) side.

A rotational combustion engine that generates force from the reciprocal motion and centripetal motion of one or more pistons that is then converted into rotational motion of a first cam and second cam wherein the cams are separated by a 2-3 degree horizontal offset and an angle of 60 degrees as well as camshaft assembly and driving shaft to provide power to an entity such as an automobile.

There is provided a water cooled engine including a cylinder head with minimized thermal strain.

A head water jacket includes an inter-exhaust-port-wall water channel between a first exhaust entrance port wall and a second exhaust entrance port wall. A cylinder head includes a cooling water injection passage provided at a bottom wall of the cylinder head. The cooling water injection passage is positioned on the exhaust end side, and includes a passage entrance provided on the exhaust end side, and a passage exit directed toward the inter-exhaust-port-wall water channel. An exhaust port wall includes a heat dissipation fin extending from a first exhaust entrance port wall toward an exhaust end. The space between the heat dissipation fin and a second exhaust entrance port wall forms a water channel entrance of the inter-exhaust-port-wall water channel.

A cylinder head for an internal combustion engine, includes: first and second valves being intake valves or exhaust valves; a first circumferential wall portion defining a first port, the first port being opened and closed by the first valve and communicating with a combustion chamber; and a first overlay welded portion formed on the first circumferential wall portion and serving as a first valve seat on which the first valve is seated.

A water cooled engine is provided, including a cylinder head with minimized thermal strain. A head water jacket includes an inter-exhaust-port-wall water channel between a first exhaust entrance port wall and a second exhaust entrance port wall. The cylinder head includes a cooling water injection passage provided at a bottom wall thereof. The cooling water injection passage is positioned on the exhaust end side, and includes a passage entrance provided on the exhaust end side, and a passage exit directed toward the inter-exhaust-port-wall water channel. An exhaust port wall includes a heat dissipation fin extending from a first exhaust entrance port wall toward an exhaust end. The space between the heat dissipation fin and a second exhaust entrance port wall forms a water channel entrance of the inter-exhaust-port-wall water channel.