Isolation diaphragm assembly for pressure transducers and method of manufacture

• US 4,199,991 A
• Filed: 05/08/1978
• Issued: 04/29/1980
• Est. Priority Date: 05/08/1978
• Status: Expired due to Term

• Current Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Original Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Inventors: Kodama, Roy K.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/903,853
• Time in Patent Office: 722 Days
• Field of Search: 73/706, 73/715, 29/454, 228/135
• US Class Current: 73/706
• CPC Class Codes: G01L 19/0046 using isolation membranes G01L13/026 and G01L19/0645 take precedence
• CPC Class Codes: Y10T 29/49877 of flexible wall, expansible chamber devices [e.g., bellows]

Abstract

An improved isolation diaphragm assembly for use in pressure transducers includes an open plenum containing an inert transmission fluid such as silicone oil. The plenum opening is bridged by a corrugated, circular diaphragm which has been tack welded at spaced locations on its periphery and then deformed into an underlying circular groove in the transducer housing, thereby providing a smooth sealing surface between the tack welds and the deformed portion. A domed cover having an O-ring seal contacting the smooth sealing surface is attached to the transducer housing so that a fluid whose pressure is to be measured may be introduced on the other side of the diaphragm from the inert transmission fluid. A method of manufacture is also disclosed.

Claims

1. In a pressure transducer of the type comprising:

a hollow transducer housing, a pressure transmitting liquid within said housing, a flexible isolation element secured to said housing with one side thereof in pressure transmitting relation to said pressure transmitting liquid and a cover secured to said housing for admitting a test fluid to the other side of said flexible isolation element, the improvement comprising;

a peripheral flange on said flexible isolation element;

a first annular sealing surface on said housing, said sealing surface having at least one annular groove formed therein and being sized to accommodate at least said peripheral flange;

a plurality of spaced tack welds securing said peripheral flange to said annular sealing surface;

means formed in said peripheral flange subsequent to said plurality of spaced tack welds for extending into said annular groove to provide a second annular sealing surface on said peripheral flange between said spaced tack welds and said annular groove, thereby to prevent radial movement of said flexible isolation diaphragm and to minimize leakage of said pressure transmitting fluid; and

seal means located in said cover for contacting said peripheral flange on said second annular sealing surface.

2. The improvement of claim 1, wherein said flexible isolation element is a thin, resilient diaphragm.

3. The improvement of claim 1, wherein said seal means is an O-ring compressed between said cover and said peripheral flange.

5. The improvement of claim 1, wherein said tack welds are at the peripheral edge of said flange.

4. A method of assembling a flexible isolation element having a peripheral flange to a transducer housing having an annular sealing surface with at least one annular groove formed therein;

comprising the steps of;

placing said peripheral flange in contact with said annular sealing surface;

tack welding said peripheral flange to said annular surface at spaced locations around said flange; and

deforming said peripheral flange into said at least one annular groove, whereby said peripheral flange is stretched between said tack weld locations and said annular groove, to provide an effective sealing surface on the side of said peripheral flange opposite said annular groove.

6. The method of claim 4, wherein said tack welding is done at the peripheral edge of said flange.