Patent ID: 6098477
Filing Date: 2000-08-08
Classification: F01B,F02B,F16H,Y10T

Abstract:
A crank device comprising a planetary gear mechanism interposed between and connected to a rotating crank member which is rotatably supported by a housing and a connecting rod which is movable in a reciprocating direction perpendicular to a rotational axis of the crank member, wherein the planetary gear mechanism includes an internally toothed sun gear fixedly mounted on the housing coaxial with the rotational axis of the crank member, and a planetary gear capable of rolling along an inner periphery of the internally toothed sun gear, a pitch circle diameter of the planetary gear being selected to be one half of a pitch circle diameter of the sun gear, a pitch circle diameter of the sun gear, a rotation center of the planetary gear being supported at a position offset from the rotational axis of the crank member, the connecting rod is pivotably connected at a position on the pitch circle of the planetary gear, whereby the connecting rod, as a whole, is adapted to be linearly reciprocated along the direction perpendicular to the rotational axis of the crank member, which converts reciprocal movement to rotational movement;the internally toothed sun gear being spaced a predetermined distance from the connecting rod,a portion of the crank member extends through the pitch circle of the internally toothed sun gear,the planetary gear and a planetary gear shaft connected at one end of the planetary gear are rotatably received within the crank member,the teeth of the planetary gear being meshed with the teeth of the internally toothed sun gear through a notch formed in an outer periphery of the crank member,the planetary gear shaft is disposed within a bore of the crank member with the other end of the planetary gear shaft protruding from an end of the bore of the crank member facing the connecting rod and is formed with an arm portion extending radially outwardly a distance corresponding to a radius of the pitch circle of the planetary gear, the one end of the connecting rod being pivotably connected to a forward end of the arm portion, anda pair of spaced bearings rotatably support opposite ends of the planetary gear shaft disposed within the crank member, one of the bearings being disposed adjacent to the connecting rod.