There is provided an assembling structure of an engine. An oil control valve unit is configured to control oil pressure in a variable valve timing device of the engine. The oil control valve unit is installed on a cylinder head. The cylinder head is assembled to a crankcase. An outer wall of the cylinder head is formed with an opening into which the oil control valve unit is partially inserted. A mating surface of the cylinder head and the crankcase is fastened by at least a pair of bolts spaced apart across the opening.

A crankcase includes: a main body portion aligned with a drive motor in a direction perpendicular to a motor drive shaft; and an extended portion continuous with the main body portion and located lateral to a motor housing, the extended portion receiving insertion of one end of the motor drive shaft. A power transmission mechanism that transmits power from the motor drive shaft to an input shaft is located partly in a first region defined by the main body portion and partly in a second region defined by the extended portion and communicating with the first region.

A hybrid vehicle includes: a crankcase extending from a lower portion of a cylinder of an engine, the crankcase including a main body portion defining a crank chamber in which a crankshaft of the engine is accommodated, the crankcase further including a breather portion projecting upwardly from the main body portion and defining a breather chamber into which blowby gas is introduced from the crank chamber; a breather tube that introduces the blowby gas from the breather chamber into the intake passage; and a drive motor disposed rearwardly of the cylinder and mounted on a top surface of the crankcase. The breather portion has a facing surface facing an outer peripheral surface of the drive motor. The facing surface of the breather portion is shaped to conform to the outer peripheral surface of the drive motor.

Provided is an engine device that can enlarge a space inside a case without lowering support stiffness. An engine (2) is attached to a case (11) via support parts (81, 82). A rear lower portion support part (82), which is one of the support parts, includes an attachment rib (11b) as a mounting part provided in the case (11) and an attachment bracket (91) fastened to a bottom of a crankcase (46) by a fastening bolt (90) and attached to the attachment rib (11b). The fastening bolt (90) penetrates through a through hole (92a) provided in the attachment bracket (91) and is screwed into a screw hole (46e) formed obliquely inward at a corner of the bottom of the crankcase (46).

An internal combustion engine includes: a crankshaft supported via a bearing; a balancer drive gear ; a balancer shaft; and a one-way clutch mechanism that transmits to the crankshaft a drive force to start the internal combustion engine. In the internal combustion engine, the bearing includes an oil seal built therein, the oil seal sealing a crank chamber of the crankcase. The one-way clutch mechanism includes a case fixed to the crankshaft and a starter driven gear provided relatively rotatably with respect to the case and driven by the drive force. The starter driven gear includes a thrust bearing portion that abuts on the balancer drive gear in an axial direction of the crankshaft.

An engine assembly includes an air-cooled engine and an external oil reservoir. The engine includes a vertically-oriented crankshaft a crankcase cover having a front portion and a rear portion, wherein the front portion of the crankcase cover and the cylinder head are located forward of a vertical plane that includes the crankshaft axis, a return pump housing formed in the exterior of the crankcase cover, a return pump positioned in the return pump housing, and a return pump inlet formed through the crankcase cover, wherein the return pump inlet is located in the front portion of the crankcase cover and the return pump inlet is located closer to the camshaft than to the crankshaft. The external oil reservoir includes an oil tank and an oil filter assembly.

There is provided an assembling structure of an engine. An oil control valve unit is configured to control oil pressure in a variable valve timing device of the engine. The oil control valve unit is installed on a cylinder head. The cylinder head is assembled to a crankcase. An outer wall of the cylinder head is formed with an opening into which the oil control valve unit is partially inserted. A mating surface of the cylinder head and the crankcase is fastened by at least a pair of bolts spaced apart across the opening.

There is provided an installation structure of an oil control valve unit configured to control a hydraulic pressure in a variable valve timing device of an engine by a control valve supported by a valve housing. The engine is formed with an installation surface on which the valve housing is installed. The valve housing is installed on the installation surface by a plurality of bolts. Two bolts of the plurality of bolts are attached at facing positions across a center of the valve housing in a direction along a cylinder axial direction of the engine.

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.