| 摘要 |
A pressure sensing device ( 10, 40 ) is shown having a ceramic capacitive sensing element ( 12 ) received in a chamber formed in a hexport housing ( 16 ). The hexport housing has a fluid passageway ( 16 c) communicating with a recessed chamber ( 16 d) formed in a bottom wall circumscribed by an annular platform shoulder ( 16 e). A thin flexible metal diaphragm ( 18 ) is hermetically attached to the bottom wall along the platform shoulder. A curable adhesive resin having a thermal coefficient of expansion and modulus of elasticity appropriately matching that of sensing element ( 12 ), such as polyurethane, is cast between the sensing element ( 12 ) and the metal diaphragm ( 18 ) forming, when cured, a layer bonded to both members resulting in a sensor that is effective in monitoring negative as well as positive fluid pressures. In one embodiment a ring is used to define layer 20 laterally and in a second embodiment an insulator sleeve ( 44 ) and shield sleeve ( 42 ) which receives pressure sensing element ( 12 ) each have an open end with an inwardly extending lip ( 44 b, 42 b) that define layer 20 laterally.
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