The rotary body according to the present invention is made of resin and attached to a crankshaft. The rotary body has an outside plate element and an inside plate element which are attached to an outside surface and an inside surface of an arm portion of the crankshaft, respectively, and a pair of filler elements disposed between the outside plate element and the inside plate element and on both sides of the arm portion. The outside plate element and the pair of the filler elements are coupled to each other, and the pair of the filler elements and the inside plate element are coupled to each other.

The rotary body according to the present invention is made of resin and attached to a crankshaft. The rotary body has an outside plate element and an inside plate element which are attached to an outside surface and an inside surface of an arm portion of the crankshaft, respectively, and a pair of filler elements disposed between the outside plate element and the inside plate element and on both sides of the arm portion. The outside plate element and the pair of the filler elements are coupled to each other, and the pair of the filler elements and the inside plate element are coupled to each other.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

A multi-link piston crank mechanism includes a crank pin bearing portion including a crank pin bearing central portion that is disposed at a center thereof in an axial direction of a crank shaft. The crank pin bearing central portion at a portion positioned on the first end side of the lower link is thicker in a radial direction of the crank pin than a portion positioned on the second end side of the lower link. The second control link end portion is thicker along a radial direction of the second through hole than the second upper link end portion along a radial direction of the first through hole.

A multi-link piston crank mechanism includes a crank pin bearing portion including a crank pin bearing central portion that is disposed at a center thereof in an axial direction of a crank shaft. The crank pin bearing central portion at a portion positioned on the first end side of the lower link is thicker in a radial direction of the crank pin than a portion positioned on the second end side of the lower link. The second control link end portion is thicker along a radial direction of the second through hole than the second upper link end portion along a radial direction of the first through hole.

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.

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.