| 摘要 |
PCT No. PCT/FR90/00790 Sec. 371 Date Jul. 19, 1991 Sec. 102(e) Date Jul. 19, 1991 PCT Filed Oct. 31, 1990 PCT Pub. No. WO91/06357 PCT Pub. Date May 16, 1991.A fluid filter clogging display comprising a case of non-magnetic material divided into an upper housing, at atmospheric pressure, and a lower housing by an impermeable membrane, a piston movable in the lower housing and dividing the lower housing into a high chamber and a low chamber, the high chamber communicating with an upstream side of a filter and the lower chamber communicating with a downstream side of the filter, a magnet mounted on the piston and disposed in the high chamber, a magnetizable detector in the upper housing for sensing a position of the magnet, a return spring located in said low chamber biasing the piston towards the impermeable membrane and a helical spring made of a shape memory alloy (SMA) which is stiff above a specific temperature and compliant below such a temperature and mounted such that the SMA spring joins the magnet to the piston depending upon the temperature thereof.
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