Patent attributes
Surface abrasion in an eccentric part of a crank pin or breakdown of the crank pin of an eccentric oscillation speed reducer is effectively prevented. A value N obtained by dividing reduction ratio M in an eccentric oscillation speed reducer by a diameter D passing a center of pin teeth is set to be smaller than 0.20. As the results, temperature of lubricant in the eccentric oscillation speed reducer can be depressed below 60° C., even though an output rotation speed at a rated torque of the eccentric oscillation speed reducer has become 28 rpm or more as required from a tact time or so in a factory, whereby a region between the eccentric part of the crank pin and a needle-shaped roller bearing is always lubricated with the lubricant which exerts required lubricating function.
