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Capacitive pressure transducer

  • US 4,227,418 A
  • Filed: 09/24/1979
  • Issued: 10/14/1980
  • Est. Priority Date: 09/24/1979
  • Status: Expired due to Term
First Claim
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1. A capacitive pressure transducer for measuring fluid pressure comprising:

  • A. a pressure sensor formed by a cylinder having one end enclosed by a deformable metal diaphragm that serves as one plate of a capacitor whose second plate is spaced from the diaphragm by an air gap constituting the dielectric of the capacitor, deformation of the sensor diaphragm in response to pressure acting to vary the air gap to produce a corresponding change in the value of the capacitance; and

    B. a coupling assembly adapted to hydraulically convey the pressure of the fluid to be measured to the pressure sensor while isolating the structure of the sensor from the fluid, said assembly including a body component having a column section and a base section, the column section being received within the cylinder with its head spaced from the sensor diaphragm to define therewith a sensor chamber which communicates through a passage in the column section with an isolation chamber formed at the bottom of the base section and sealed by a barrier diaphragm, the chambers and the passage being filled with hydraulic fluid whereby the pressure of fluid imposed on the barrier diaphragm is transferred to the sensor diaphragm.

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