Patent ID: 6684735
Filing Date: 2004-02-03
Classification: F16F,F16H,Y10T

Abstract:
A torsionsal damper mounted to a crank shaft of an internal combustion engine, comprising:a cylindrical metal boss fitted to said crank shaft and having an outer circumferential surface with which an oil seal provided in an engine assembly makes contact: a hub which has a fixing portion welded to an end surface of said boss and a cylindrical rim portion integrally and concentrically formed in an outer circumerential side of the fixing portion, and which is formed by one of a sheet metal and a cold forging operation; a cylindrical mass body concentrically arranged in an outer side of said rim portion; and a cylindrical elastic body provided between said rim portion and said mass body, wherein a metal material of said hub is set to have a carbon equivalent of 0.5% or less and a metal material of said boss is set to have a carbon equivalent of 0.5% or less and a carbon content of 0.2% or more so that no heat treatment need be applied to the weld portion between said fixing portion and said boss after welding, and a portion making contact with the oil seal is quenched-hardened.