| 摘要 |
PROBLEM TO BE SOLVED: To set a damping force on extension side/retraction side to soft/soft in a fail state in a damping force variable hydraulic damper capable of adjusting the damping force on the extension side/retraction side to hard/soft, soft/soft, or soft/hard. SOLUTION: Spring forces of bias springs 38 and 41 and a shape memory alloy spring 43 are applied to a spool 27 for adjusting damping force, and the damping force is adjusted by moving the spool 27 against these spring forces by a proportional solenoid 35. The shape memory alloy spring 43 is electrically connected in series to the coil 44 of the proportional solenoid 35. The shape memory alloy spring 43 is heated by the energization of the coil 44 in a normally operating state to extend so as to act as the return spring of the spool 27. In the fail state, the energization of the coil 44 is stopped to lower the temperature of the shape memory alloy spring 43, and the shape memory alloy spring tends to be easily deformed. Accordingly, the shape memory alloy spring is compressed by the bias springs 38 and 41 to move the spool 27 so as to set a damping force to a proper damping force. COPYRIGHT: (C)2007,JPO&INPIT
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