Pressure transducer

• US 3,942,382 A
• Filed: 10/16/1974
• Issued: 03/09/1976
• Est. Priority Date: 10/17/1973
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Hok, Bertil
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/515,682
• Time in Patent Office: 510 Days
• Field of Search: 73/398 AR, 73/398 C, 73/398 R, 128/2.05 D, 128/2.07, 338/36, 338/38, 338/86
• US Class Current: 73/753
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: G01L 9/0092 using variations in ohmic resistance
• CPC Class Codes: G01L 9/025 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

A pressure transducer including a measuring cell which is partly filled with a liquid and with the remainder being filled with a gas; a conduit filled with the liquid extending from the measuring cell, and which is open at an end thereof remote from the measuring cell; and means in the pressure transducer for generating an electrical value which corresponds to the particular gas volume.

Claims

1. A pressure transducer for generating an electrical signal in conformance with a liquid pressure, said transducer comprising a measuring cell including a chamber partly filled with a liquid and the remaining part thereof with a gas entrapped in said chamber;

a conduit filled with said liquid having one end thereof communicating with the liquid-filled part of the chamber of said measuring cell, said conduit having an open end remote from said measuring cell communicating with a fluid-filled vessel for measurement of the fluid pressure in the latter;

tube means extending into said chamber connected to a source for supplying quantities of said liquid to said chamber;

valve means for selectively restricting flow of liquid from said liquid supply source and for sealing said tube means, said gas volume in said chamber being varied responsive to the fluid pressure in said fluid vessel acting on the liquid in said conduit; and

means in said transducer for generating an electrical value of a magnitude in conformance with the particular gas volume.

2. A pressure transducer as claimed in claim 1, comprising a thermally dependent resistance adapted to influence the electrical signal in conformance with the particular temperature in said measuring cell.

3. A pressure transducer as claimed in claim 1, said liquid in said measuring cell comprising an electrolyte.

4. A pressure transducer as claimed in claim 3, said liquid comprising physiological saline solution.

5. A pressure transducer as claimed in claim 3, comprising two electrodes extending into said liquid;

and a circuit arrangement connected to said electrodes for measuring the particular ohmic resistance between said two electrodes.

6. A pressure transducer as claimed in claim 5, said electrodes being constituted of platinum.

7. A pressure transducer as claimed in claim 1, comprising two condensor layers being located interiorly of said transducer;

and means insulating said condensor layers from said liquid, said condensor layers being positioned so that the quantity of liquid therebetween varies in conformance with the pressure being measured.

8. A pressure transducer as claimed in claim 5, said liquid in said measuring cell having the thermal coefficient for the specific resistance thereof selected so as to eliminate temperature influences on said gas volume.

9. A pressure transducer as claimed in claim 7, said liquid in said measuring cell having the specific dielectric value thereof selected so as to eliminate temperature influences on said gas volume in said measuring cell.