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 internal combustion engine includes a crankshaft having a first end and a second end opposite the first end. The crankshaft defines a crank axis and is rotatable about the crank axis. The internal combustion engine also includes a camshaft that defines a camshaft axis and is rotatable about the camshaft axis. The internal combustion engine further includes a cam drive assembly that is operable to transfer rotation from the crankshaft to the camshaft, a balance mass rotatable about the crankshaft, and a balancer drive assembly operable to drive the balance mass through the cam drive assembly.

An engine system has a crankshaft gear coupled to an engine crankshaft and a balance gear coupled to a balance shaft. The balance gear is formed by a disc having first and second opposite sides and a series of teeth. A first sector of the disc has at least one aperture therethrough, and a second opposite sector of the disc defines a recess intersecting the first side. The balance gear has a damper formed by a cover plate connected to the first side to enclose the recess and contain a plurality of particles therein. A gear and a method of forming a gear is also provided, with the gear having a first sector defining at least one aperture therethrough and a second sector defining a recess intersecting the first side. A plurality of particles are positioned in the recess, and a cover plate encloses the recess to form a damper.

An engine system has a crankshaft gear coupled to an engine crankshaft and a balance gear coupled to a balance shaft. The balance gear is formed by a disc having first and second opposite sides and a series of teeth. A first sector of the disc has at least one aperture therethrough, and a second opposite sector of the disc defines a recess intersecting the first side. The balance gear has a damper formed by a cover plate connected to the first side to enclose the recess and contain a plurality of particles therein. A gear and a method of forming a gear is also provided, with the gear having a first sector defining at least one aperture therethrough and a second sector defining a recess intersecting the first side. A plurality of particles are positioned in the recess, and a cover plate encloses the recess to form a damper.

A torsional vibration damper mounted at a crankshaft of an engine is provided. The torsional vibration damper comprises a hub having a first mounting surface and a second mounting surface opposite to the first mounting surface, an inertia ring and an elastomer element disposed between the hub and the inertia ring. The hub includes a first mounting hole configured to receive the crankshaft, and at least one slot spaced apart from the first mounting hole. The slot is configured such that a center-of-gravity of the torsional vibration damper is offset from a central axis of the crankshaft.

An air compressor includes a rotating device pivotally connected to a piston body. The rotating device includes a gear body and a counterweight. The gear body is formed together with a counterweight, wherein the counterweight is provided with a crankshaft corresponding to the center of the gear body and a crankpin placed at a distance from the crankshaft. The counterweight is horizontally divided into two integrally formed halves, including a left half and a right half, with a common line connected between the center of the crankshaft and the center of the crankpin, wherein the left half has a weight different from the right half, so that the piston body gathers more rotational momentum from the counterweight at BDC to facilitate upstrokes, so that the piston body can conduct reciprocating motion more smoothly, and thus the service life of the air compressor can be increased.

A torsional vibration damper mounted at a crankshaft of an engine is provided. The torsional vibration damper comprises a hub having a first mounting surface and a second mounting surface opposite to the first mounting surface, an inertia ring and an elastomer element disposed between the hub and the inertia ring. The hub includes a first mounting hole configured to receive the crankshaft, and at least one slot spaced apart from the first mounting hole. The slot is configured such that a center-of-gravity of the torsional vibration damper is offset from a central axis of the crankshaft.

A power unit for a hybrid vehicle is provided with a twin-cylinder reciprocating piston engine, which has two pistons which are guided in two cylinders in tandem arrangement. Two counter-directional crankshafts are connected with the pistons by connecting rods. At least one generator is rotatable co-directionally to the first crankshaft and counter-directionally to the second crankshaft. A camshaft with valve cams are operatively connected with control valves. A flywheel mass element is arranged on the second crankshaft or on a flywheel mass compensating shaft, and a compensating camshaft are provided. The compensating camshaft includes at least one compensating cam element which is operatively connected with a linearly guided compensating mass.