A balance device for an internal combustion engine includes a crankshaft and a balance shaft. The crankshaft includes a CS eccentric weight. The balance shaft includes a BS eccentric weight. A CS connected point deviated from the CS main shaft, and a BS connected point deviated from the BS axial shaft are connected with a connection rod. A CS connection mechanism that enables relative rotation of the crankshaft and the connection rod is provided at the CS connected point. A BS connection mechanism that enables relative rotation of the balance shaft and the connection rod is provided at the BS connected point. A guide section guides a motion of the connection rod so that the balance shaft rotates in an opposite direction to the crankshaft.

A reciprocating-piston internal combustion engine includes first, second, and third cylinders, and a crank drive having a crankshaft rotatably mounted in a crank housing. The crankshaft has first and second crank pins, wherein a first and a second connecting rod for a first and a second piston are assigned to the first crank pin, and a third connecting rod for a third piston is assigned to the second crank pin. The first and the second cylinder together with the first and the second piston are arranged in a V-shape, wherein the third cylinder together with the third piston is arranged in the V.

An apparatus for vibration reduction in a linear actuator includes one or more sets of counterweights, one or more enclosures configured to receive one set of counterweights for each enclosure, and a driving shaft configured to mount the one or more sets of counterweights. The one or more sets of counterweights are disposed symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator. The driving shaft extends perpendicularly and transversely through the longitudinal axis and the plane. A portion counterweight of a given set of counterweights may rotate clockwise and another portion counterweight of the given set of counterweights may rotate counterclockwise.

An apparatus for vibration reduction in a linear actuator includes one or more sets of counterweights, one or more enclosures configured to receive one set of counterweights for each enclosure, and a driving shaft configured to mount the one or more sets of counterweights. The one or more sets of counterweights are disposed symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator. The driving shaft extends perpendicularly and transversely through the longitudinal axis and the plane. A portion counterweight of a given set of counterweights may rotate clockwise and another portion counterweight of the given set of counterweights may rotate counterclockwise.

An engine includes a cylinder system, a driving system including a piston and a crankshaft, a power generating system and a cooling system. The power generating system is disposed on a side of the driving system and includes a generator and a counterweight. The generator includes a main body and a rotor pivotally disposed within the main body. The cooling system is disposed on an opposite side of the driving system and includes a first water pump in fluid communication with the cylinder system. An outline of the rotor is projected along the crankshaft to form a first projecting zone. Projections of the first water pump and the driving system along the crankshaft overlap the first projecting zone.

An offset in-line four cylinder engine has reduced vibration generated by a secondary inertia couple based on lateral pressures from pistons. A reference line passes through a shaft center of a crankshaft and is parallel or substantially parallel to cylinder axes of four cylinders as viewed in the axial direction of the crankshaft. As viewed in the axial direction of the crankshaft, the direction in which the reference line extends is referred to as first direction, and the direction perpendicular to the first direction is referred to as second direction. A distance between the shaft center of a first balancer shaft and the reference line as measured in the second direction is different from the distance between the shaft center of a second balancer shaft and the reference line as measured in the second direction, or a magnitude of a first unbalancing portion is different from a magnitude of the second unbalancing portion.

A motorcycle has a crankcase containing a crank shaft and a balancer shaft, and a cylinder and a cylinder head positioned above the crankcase, and an exhaust pipe extends from the cylinder head. The balancer shaft is positioned in front of the crank shaft, and the crankcase has a balancer shaft housing supporting the balancer shaft thereinside, and has a recessed part depressed rearward in a front end center part of the balancer shaft housing. The balancer shaft has balancer shaft weights apart from each other in one side and in the other side in an axis direction.

An idle gear assembly comprises an outer ring having gear teeth formed on an external surface thereof and engaged with a crank gear and any one of the left and right balance gears. A bearing includes an inner member and an outer member in a radial direction of the bearing and a plurality of rolling bodies disposed between the inner member and the outer member. A ring has elasticity in a radial direction thereof. A hub has a flange, which is in contact with the bearing, and a penetration hole. The flange and the penetration hole are formed at one side of the hub in an axial direction. A nut is inserted through another side and mounted at a hollow portion of the ring. A bolt is inserted through the insertion hole of the bearing, the penetration hole, and the nut and fixes the bearing and the hub.

A rolling vibration reduction device for an internal combustion engine includes: a main inertial system configured to rotate with a crankshaft of the internal combustion engine; a driving force transmission mechanism configured to transmit a rotational driving force of the crankshaft, a direction of the rotational driving force being reversed by the driving force transmission mechanism; and a sub-inertial system configured to rotate by the rotational driving force transmitted from the driving force transmission mechanism and to reduce rolling vibration of the internal combustion engine associated with rotation of the crankshaft by rotating in an opposite direction to the crankshaft. A torsional resonance frequency in the rolling vibration reduction device is set to a value higher than an explosion primary frequency at a maximum engine speed in a preset operating region of the internal combustion engine.

A balance weight includes a main weight portion extending over a range defined by a circular-arc circumferential edge centered at a rotational shaft hole side and a pair of virtual end surfaces located on the circular-arc circumferential edge on both sides of the rotational shaft hole, a pair of extension weight portions extending from the pair of virtual end surfaces to an opposite circular-arc side of the rotational shaft hole from the circular-arc circumferential edge, the rotational shaft hole provided at the main weight portion so as to be located on a central side of the circular-arc circumferential edge, a crank shaft attachment protrusion, a crank shaft hole provided at the crank shaft attachment protrusion radially eccentrically with respect to the rotational shaft hole, and a pair of spaces formed between positions on both sides of the crank shaft attachment protrusion and the pair of extension weight portions, respectively.