An engine cooling device includes a heater circulation passage including an exhaust-side channel and a heater channel, the exhaust-side channel extending through an exhaust port-side portion of a cylinder head, the heater channel extending through a heater core; an auxiliary device circulation passage including a main channel and an auxiliary device channel, the main channel extending through a portion of the cylinder head other than the exhaust port-side portion, the auxiliary device channel extending through an auxiliary device; a temperature detecting portion configured to detect a temperature of an engine; and a channel switching valve configured to perform connection between the main channel and the auxiliary device channel and connection between the heater circulation passage and the auxiliary device circulation passage depending on the detected temperature falling within one of three temperature ranges.

A split cooling system of an internal combustion engine may include a water pump configured to circulate cooling water; a cylinder head and a cylinder block configured to be supplied with the cooling water from the water pump; an integrated flow control valve configured to include an inlet provided to be supplied with the cooling water of the cylinder head and a plurality of valves that are configured to be opened or closed to distribute the cooling water introduced through the inlet to an oil heat exchanger, a heater core, and a radiator; and a split cooler configured to be mounted at the cylinder block to provide a split cooling channel in the cylinder block and the cylinder header.

A split cooling system of an internal combustion engine may include a water pump configured to circulate cooling water; a cylinder head and a cylinder block configured to be supplied with the cooling water from the water pump; an integrated flow control valve configured to include an inlet provided to be supplied with the cooling water of the cylinder head and a plurality of valves that are configured to be opened or closed to distribute the cooling water introduced through the inlet to an oil heat exchanger, a heater core, and a radiator; and a split cooler configured to be mounted at the cylinder block to provide a split cooling channel in the cylinder block and the cylinder header.

A cylinder block assembly may include a cylinder block, a cylinder body disposed in the cylinder block, with a plurality of cylinder bores formed in the cylinder body, a fluid jacket, which is formed between an inner circumferential surface of the cylinder block and an outer circumferential surface of the cylinder body, and through which coolant flows, and a block insert disposed in the water jacket and configured to guide a flow of coolant, wherein the cylinder block may include a second block coolant outlet, which is formed at a second side in a surface of an exhaust side of the cylinder block, and through which the coolant in the water jacket is discharged, and wherein the exhaust side may include a side at which combustion gas is exhausted out of the cylinder body.

A cylinder block assembly may include a cylinder block, a cylinder body disposed in the cylinder block, with a plurality of cylinder bores formed in the cylinder body, a fluid jacket, which is formed between an inner circumferential surface of the cylinder block and an outer circumferential surface of the cylinder body, and through which coolant flows, and a block insert disposed in the water jacket and configured to guide a flow of coolant, wherein the cylinder block may include a second block coolant outlet, which is formed at a second side in a surface of an exhaust side of the cylinder block, and through which the coolant in the water jacket is discharged, and wherein the exhaust side may include a side at which combustion gas is exhausted out of the cylinder body.

A first coolant flow passage is provided to extend in a longitudinal direction of a cylinder head. In at least one of cross sections perpendicular to the longitudinal direction, the first coolant flow passage is located between a flat plane including central axes of a plurality of combustion chambers and parallel to the longitudinal direction and a central line plane including central lines of a plurality of intake ports. In at least one of cross sections perpendicular to the longitudinal direction, at least a portion of a second coolant flow passage is located between the combustion chamber and the first coolant flow passage. A coolant at a temperature lower than that of a coolant flowing in the second coolant flow passage flows in the first coolant flow passage.

A first coolant flow passage is provided to extend in a longitudinal direction of a cylinder head. In at least one of cross sections perpendicular to the longitudinal direction, the first coolant flow passage is located between a flat plane including central axes of a plurality of combustion chambers and parallel to the longitudinal direction and a central line plane including central lines of a plurality of intake ports. In at least one of cross sections perpendicular to the longitudinal direction, at least a portion of a second coolant flow passage is located between the combustion chamber and the first coolant flow passage. A coolant at a temperature lower than that of a coolant flowing in the second coolant flow passage flows in the first coolant flow passage.

Provided is an engine with a starter valve arranged in a compact space and with a cylinder head having a cooling water passage and a starter valve feeding compressed air to a combustion chamber. The starter valve is arranged parallel in the axial direction to a cylinder while fitted into a sleeve, and a portion of the cooling water passage is formed by the outer surface of the sleeve fitted into a starter valve insertion hole formed in the cylinder head. A starting air passage orthogonal to the axial direction of the starter valve insertion hole is formed in the cylinder head, and a portion of the wall surface of the starting air passage is formed by the end surface on one side of the sleeve.

Provided is an engine with a starter valve arranged in a compact space and with a cylinder head having a cooling water passage and a starter valve feeding compressed air to a combustion chamber. The starter valve is arranged parallel in the axial direction to a cylinder while fitted into a sleeve, and a portion of the cooling water passage is formed by the outer surface of the sleeve fitted into a starter valve insertion hole formed in the cylinder head. A starting air passage orthogonal to the axial direction of the starter valve insertion hole is formed in the cylinder head, and a portion of the wall surface of the starting air passage is formed by the end surface on one side of the sleeve.

Oil distribution blocks and oil distribution systems equipped therewith. Such an oil distribution block includes a rigid block body configured to be secured to a cylinder head of an engine, an oil inlet, and an oil outlet. The oil inlet is configured to be releasably coupled to a first oil distribution line or a fitting therebetween, receive a flow of oil therefrom, and route the oil to an inlet of a cooling passage of the cylinder head. The oil outlet is configured to be releasably coupled to a second oil distribution line or a fitting therebetween, receive a flow of oil from an outlet of the cooling passage of the cylinder head, and route the oil to the second oil distribution line. The oil inlet and the oil outlet are configured to threadably couple with the first and second oil distribution lines, respectively, or the fittings therebetween.