To provide a coil spring capable of improving durability against the contact of mutual wires by reducing a hysteresis loss caused by frictional resistance with a mating member.
An arc spring 41 is arranged in a clutch unit 1. For reducing the hysteresis loss, an abrasion resistant layer having a friction coefficient μ smaller than 0.15 and a hardness of Hv1000 or larer is formed on a surface of the arc spring 41. The abrasion resistant layer is an MoS2 layer (a molybdenum disulfide layer), an electroless NiP layer (an electroless nickel phosphorus layer), a DLC layer (a diamond-like carbon layer) or a TiN layer (a titanium nitride layer). Except the case using the MoS2 layer, abrasion resistance can also be improved. Particularly in the DLC layer, since the hardness is about HV3000, the DLC layer is suitably formed on a coil spring surface indicated in Fig.2 of requiring high abrasion resistance.
AMANO TANEHIRA
KATO SHINJI
KOBAYASHI TAKAO
YAMADA HIROTAKA
| JP2008248905A | 2008-10-16 | |||
| JP2004169859A | 2004-06-17 | |||
| JP2004278588A | 2004-10-07 |