An engine includes: a crankcase; a cover that is connected to the crankcase at a mating surface of the cover inclined toward an inner side in a vehicle width direction in going downward when the engine is mounted to a vehicle body, the cover covering a protruding end of a rotary shaft; and attachment bosses that are formed to be integral with the cover, have a predetermined height from the mating surface, and accept fastening members for fastening the cover to the crankcase. Accordingly, when mounted on a two-wheeled motor vehicle, the engine can restrain protrusion in the vehicle width direction and can be disposed at a position as low as possible with reference to the vehicle.

Aspects of the present disclosure are directed to a cylinder housing of an internal combustion engine. In one embodiment of the present disclosure, the cylinder housing includes at least two adjacently arranged cylinders, each of which includes a wet cylinder liner, a support structure, and a coolant jacket arranged between the support structure and the cylinder liner. The cylinder housing further including at least one screw receptacle for a cylinder head screw, and is positioned between at least two adjacently arranged cylinders in a region of at least one engine transverse plane.

An engine cylinder block includes a cylinder block housing and a double-crankshaft mechanism installation case located at a downside of the cylinder block housing. The cylinder block housing is integrally connected with the double-crankshaft mechanism installation case. The cylinder block housing is provided with a cylinder block cavity. The double-crankshaft mechanism installation case is enclosed and formed by an end cover and a side cover. A piston rod guiding groove is installed in the double-crankshaft mechanism installation case. A connecting rod sliding groove is configured through the piston rod guiding groove. A crank operation cavity is configured on both sides of the piston rod guiding groove. A main spindle installation hole is configured on the shell at both ends of each crank operation cavity. A main spindle supporting portion is configured below the main spindle installation hole.

A cylinder block of an internal combustion engine includes a cylinder bore wall that holds a piston so as to allow the piston to reciprocate. In at least one part of the cylinder bore wall in a cylinder axial direction, the density of a layer located farther from a cylinder head is lower than the density of a layer located closer to the cylinder head in the cylinder axial direction.

A structural frame is provided. The structural frame includes a bottom surface, first and second cylinder block sidewall engaging surfaces, the first and second cylinder block sidewall engaging surfaces positioned above the bottom surface at a height that is above a centerline of a crankshaft support included in a cylinder block when the structural frame is coupled to the cylinder block.

The invention relates to a power unit, in particular for a hybrid vehicle, comprising a two-cylinder reciprocating piston engine comprising two pistons guided in two cylinders in tandem arrangement, and two counter-rotating crankshafts connected to the pistons by connecting rods, a generator which is rotatable in the same direction as the first crankshaft and in the opposite direction to the second crankshaft, and a balancer shaft which is rotatable in the same direction as the second crankshaft and in the opposite direction to the first crankshaft. The generator is operatively connected directly to the first crankshaft by a first traction mechanism and the balancer shaft is operatively connected directly to the second crankshaft by a second traction mechanism. The balancer shaft and/or the second crankshaft support(s) a flywheel mass element. The invention further relates to a vehicle, in particular a hybrid vehicle, having such a power unit.

An internal combustion engine includes: a cylinder block including a bulkhead formed so as to separate adjacent cylinders; a crankshaft including a counterweight; and a gas-vent hole which is formed in the bulkhead within a radius of rotation of the counterweight when seen from below a piston bottom-dead-center position and an axial direction of the crankshaft, and which communicates between the adjacent cylinders. The counterweight includes at least one of a concave portion and a through-hole formed at at least a part of a region of the counterweight opposed to the gas-vent hole during rotation of the crankshaft. The concave portion hollows in a direction away from the gas-vent hole, the through-hole penetrating through the counterweight in a direction away from the gas-vent hole.

A first die segment for forming an internal combustion engine block has cylindrical projections, and die core pieces disposed about the cylindrical projections. A second die segment has die core stubs positioned so as to extend between adjacent die core pieces when the segments are brought together. An engine block formed by the die segments has cylindrical bores formed by the cylindrical projections extending from the deck of the block and voids formed by the die core pieces also extending from the deck and disposed about the cylindrical bores. Pockets formed by the die core stubs extend into sides of the engine block between adjacent voids. The engine block is worked below the level of the deck to undercut each of the pockets, removing material between them and the voids to result in an interconnected water jacket extending about the cylindrical bores, while leaving the deck closed.

A novel cylinder head arrangement for an in-line four cylinder or eight cylinder engine. A modified arrangement allows additional space for installation of wider rocker arm assemblies used for variable valve lift (VVL), cylinder deactivation (CDA) and other types of variable valve actuation (VVA). In one embodiment, cam towers adjacent the end two cylinders are not used. At least one end support is used, which may be an outboard bearing on a camshaft for each end. The wider rocker assemblies may then be installed. In another embodiment, cam towers adjacent the inner two cylinders are eliminated and a single camshaft support piece with a support bearing is installed between the inner cylinders to provide support for the camshafts. The wider rocker assemblies may then be installed on at least one of the middle cylinders. A novel oil control valve operates latches in switching rocker arm assemblies.

A cylinder block of an engine is provided. The cylinder block includes a cast body defining one or more cylindrical bores. The cylinder block also includes a crankshaft bearing wall formed within the cast body. The crankshaft bearing wall is configured to be removably coupled with a bearing cap to define an opening for rotatably supporting a crankshaft of the engine. The cylinder block further includes a chamfered shoulder portion casted on the crankshaft bearing wall.