In a vehicle power unit having an internal combustion engine, a pair of power transmission gears for transmitting rotation of a crank shaft to a balancer shaft is arranged between a crankcase and a crankcase cover, and a fluid pump is provided on a power transmission gear shaft supporting a power transmission gear, by which the backlash between the crank shaft and the balancer shaft is reduced and the friction and the noise of the gears are restrained while achieving downsizing of the gears of the crank shaft and the balancer, weight reduction and downsizing of the power unit.

There is provided an engine water-cooling device that can increase warming-up efficiency of an engine. The engine water-cooling device includes a thermostat housing that houses a thermostat. The thermostat housing is mounted to a front wall of a cylinder head in one side portion in a width direction of the cylinder head. A cooling water pump is mounted to a front wall of a cylinder block in a central portion in a width direction of the cylinder block. A bypass passage includes an intra-head bypass passage in the cylinder head, and the intra-head bypass passage includes a width-direction passage portion extending from a position behind the thermostat housing to a position behind and above the cooling water pump.

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.

An engine cooling system may include a main intake line for supplying external air to an intake manifold attached to an engine including a cylinder block and a cylinder head, a supplementary intake line branched from one side of the main intake line and joined to the other side of the main intake line, an intake route control valve in the main intake line, a main exhaust line for flowing exhaust gas from an exhaust manifold, an exhaust route control valve in the main exhaust line, a turbocharger, an intercooler mounted to the supplementary intake line on a downstream side of the turbocharger, an EGR cooler branched from the exhaust manifold for recirculating the exhaust gas and provided in an EGR line connected to the main intake line; and a cooling line for flowing a coolant supplied from a water pump to cool the EGR cooler, the exhaust route control valve and/or the turbine housing of the turbocharger.

The present invention relates to a liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each cylinder is surrounded by a respective cooling liner and each cylinder head has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, wherein the transition channels of at least two cylinders are interconnected via a pressure compensation chamber.

An engine having a water jacket may include a cylinder block in which cylinder liners forming a combustion chamber may be disposed from a first end to a second end of the cylinder block, and a block water jacket may be formed around the cylinder liners, a cylinder head having a head water jacket coupled to a top of the cylinder block, receiving cooling water from an exhaust side of the block water jacket and discharging cooling water to an intake side of the block water jacket, and inserts that may be inserted into the block water jacket and that may have horizontal dividing blades dividing the block water jacket into upper and lower parts, legs extending downward from the horizontal dividing blades, and flow preventing protrusions protruding upward from the horizontal dividing blades to divide the upper part of the block water jacket.

A water jacket for a cylinder head provided inside a cylinder head including a protruded part formed with an exhaust outlet exhausting an exhaust gas includes an upper water jacket for moving a coolant on an exhaust passage connected with the exhaust outlet inside the protruded part, a lower water jacket for moving a coolant under an exhaust passage connected with the exhaust outlet inside the protruded part, and at least one connection part mutually connecting the upper water jacket and the lower water jacket to enable the flow of coolant to a side of the exhaust outlet from the inside of the protruded part.

A water-jacket structure of a cylinder head may include a plurality of intake side inlet passages installed at intake sides of the cylinder head, respectively, along a length direction of the cylinder head to introduce cooling water supplied from the water-jacket of a cylinder block into the water-jacket of the cylinder head, a combustion chamber cooling passage cooling a combustion chamber using the cooling water supplied from the intake side inlet passage, a plurality of exhaust side outlet passage disposed at exhaust sides of the cylinder head, respectively, along a the length direction of the cylinder head to discharge the cooling water passing through the combustion chamber cooling passage, and an exhaust side gallery communicating with the exhaust side outlet passage to gather the cooling water discharged from the exhaust side outlet passage.

A cylinder head assembly for an internal combustion engine includes a cast cylinder head defining a combustion chamber and fabricated from a first material, and an internal support structure at least partially encapsulated within the cast cylinder head. The internal support structure is fabricated from a thermal strain and fatigue resistant second material, different from the first material, such that during engine operation, thermal and mechanical loads are transferred to the internal support structure to reduce combustion chamber displacement. The internal support structure and the cylinder head are bonded via a hot isostatic pressing (HIP) process to eliminate internal porosity and gaps therebetween.

A spark ignition engine includes: a pre-chamber (PC); a main chamber (MC); and a cylinder head coupled with a water jacket. The PC includes: a spark plug; and a PC body. The spark plug is surrounded by a jacket with thermal-conductive substance. The thermal-conductive substance is solid at room temperature and liquid at working temperature of the PC. At working temperature of the PC, the liquid thermal-conductive substance conducts heat from the spark plug to the water jacket. The PC body is coated with a layer of non-thermal-conductive substance.