| 摘要 |
PROBLEM TO BE SOLVED: To provide a damper for sufficiently absorbing torsional vibration of a crank shaft, even when used under extremely low temperature circumstances. SOLUTION: To a crank shaft of an engine, a hub is fixed for integral rotation, and an inertia mass arranged outside the hub is joined to the hub with a rubber elastic body. The ratio (F<SB>-30</SB>/F<SB>60</SB>) of the natural frequency (F<SB>-30</SB>) of the damper in the torsional direction at -30°C to the natural frequency (F<SB>60</SB>) in the torsional direction at 60°C is 1.5 or less. The ratio (E'<SB>-30</SB>/E'<SB>60</SB>) of the storage elastic modulus (E'<SB>-30</SB>) of the rubber elastic body at -30°C to the storage elastic modulus (E'<SB>60</SB>) at 60°C is 3.0 or less. The rubber elastic body mainly contains an ethylene-propylene copolymer rubber consisting of ethylene having a weight percentage of 51% or less. Aliphatic dibasic acid ester plasticizer of 5-30 pts.wt. is incorporated in the ethylene-propylene copolymer rubber of 100 pts.wt. COPYRIGHT: (C)2005,JPO&NCIPI
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