| 摘要 |
966,542. Piezoelectric gauges. H. LIST. Sept. 30, 1960 [Oct. 2, 1959], No. 33622/60. Heading G1N. [Also in Division H1] In a piezoelectric gauge of the type used for measuring the pressure in the cylinders of internal-combustion engines comprising a casing and a sleeve attached thereto enclosing the piezo elements, the annular gap between the elements and the sleeve is filled with a highly insulating solid or liquid polymer. In Fig. 1 two quartz crystals 4 and 5 sense pressure communicated through a transfer head 6 and develop charges at electrodes 7 and 8 which are taken off via lead 12 and the casing, a layer 10 of soft metal such as aluminium providing a low-resistance contact. Coolant flows through channels 18 into an annular chamber 13 around the crystals, which are fitted in a sleeve 3 but insulated therefrom by an annular gap 19 filled with an insulating polymer. The latter may be solid, such as poly-tetrafluorethylene, but is preferably liquid so that it can also be used as the coolant. In the latter case the sleeve is perforated at 20 with axially extending slots staggered in a circumferential direction of the sleeve (Fig. 2, not shown). A silicone oil is suitable as coolant and insulant. If a solid polymer is used, this may be formed in situ by pouring in a liquid precursor, with or without a catalyst, and allowing to stand or heating to 100‹C. until converted into solid form.
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