Static pressure sensor with glass bonded strain gauge transducers

• US 4,445,385 A
• Filed: 04/30/1982
• Issued: 05/01/1984
• Est. Priority Date: 04/30/1982
• Status: Expired due to Fees

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: International Telephone & Telegraph Corp. (ITT, Inc.)
• Inventors: Endo, Teruyuki
• Primary Examiner(s): Goldberg, Gerald
• Assistant Examiner(s): Noland, Tom
• Application Number:
  US06/373,405
• Time in Patent Office: 732 Days
• Field of Search: 73/726, 73/727, 73/DIG. 4, 73/706, 338/4, 338/2, 338/3, 338/5
• US Class Current: 73/726
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: G01L 9/06 of piezo-resistive devices

Abstract

The disclosure is drawn to a statc pressure unit having a circular dividing fitting with two silicon strain gauges glass bonded thereto. The strain gauges are located to place one strain gauge in tension and one in compression when the fitting is pressurized. One of two embodiments may be employed. In either case, one strain gauge is positioned in tension symmetrically across the center of the fitting. The other strain gauge is placed so that it is in compression.

Claims

1. A transmitter comprising:

a fluid housing having a wall;

a fitting including an externally threaded hollow shank forming a cylindrical passageway about a central axis therein, said shank having a circular disc centered perpendicularly about said passageway axis, said disc being welded to said shank covering one end of said passageway, said fitting being threaded into and sealed in a fixed position in said wall, a central portion of said disc expanding outwardly of said housing when a fluid is held therein at a pressure inside said passageway higher than that on the outside of said disc;

first and second strain gauges glass bonded to the same outside surface of said disc in positions to increase and to decrease in resistance as said disc expands outwardly, said first strain gauge being transversely and longitudinally centered symmetrically on a diametral line through the center of said central portion, said second strain gauge being transversely centered on the same said diametral line but longitudinally spaced from said first strain gauge; and

means connected from said first and second strain gauges to produce an electrical output signal which is a first function of the resistances of said first and second strain gauges, said first function being a second function of the pressure within said passageway, each of said first and second strain gauges being approximately the same size, rectangular in top and bottom plan, substantially uniform in thickness, and glass bonded to the external circular surface of said disc, the center of said first strain gauge lying on the axis of said passageway, the longitudinal axis of said first strain gauge being the same as that of said second strain gauge, a line normal to said circular disc surface through the center of said second strain gauge being tangent to the cylindrical surface of said passageway.