An engine assembly includes a small air-cooled engine and a dry sump lubrication system including an external oil reservoir, wherein the dry sump lubrication system has an overall oil capacity that provides at least five hundred hours of engine oil life.

An engine assembly includes a small air-cooled engine and a dry sump lubrication system including an external oil reservoir, wherein the dry sump lubrication system has an overall oil capacity that provides at least five hundred hours of engine oil life.

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.

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 engine includes a crankshaft and a timing gear to be attached to the crankshaft so as to rotate integrally with the crankshaft. A fitting projection is provided on either one of the crankshaft and the timing gear, and a fitting recess to be fitted with the fitting projection, and erroneous-assembling prevention ribs to sandwich the fitting recess in a circumferential direction are provided on the other one of the crankshaft and the timing gear.

A crankcase for a reciprocating piston engine, in particular of a motor vehicle, includes at least first one wall region that has a greater wall thickness than at least one second wall region of the crankcase that adjoins the first wall region. The crankcase is produced from an aluminum alloy and by at least mainly laminar die casting and is heat-treated completely or heat-treated completely and additionally locally or heat-treated only locally.

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.

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.

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 includes a crankshaft and a timing gear to be attached to the crankshaft so as to rotate integrally with the crankshaft. A fitting projection is provided on either one of the crankshaft and the timing gear, and a fitting recess to be fitted with the fitting projection, and erroneous-assembling prevention ribs to sandwich the fitting recess in a circumferential direction are provided on the other one of the crankshaft and the timing gear.