Differential pressure measuring cell

Patent metadata

Field	Value
Publication number	US-10247631-B2
Application number	US-201515323481-A
Country	US
Kind code	B2
Filing date	Jun 8, 2015
Priority date	Jul 8, 2014
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

A differential pressure measuring cell comprises a measuring membrane; two opposing bodies; and one converter. The measuring membrane is arranged between the opposing bodies and is connected in a pressure-tight manner to the two opposing bodies, forming in each case one measuring chamber. The opposing bodies each have a pressure duct through which a pressure can be made to act upon the respective measuring chamber. The converter is provided in order to convert a deformation of the measuring membrane, which deformation is dependent upon a difference between the pressures, into an electrical signal; wherein the opposing bodies each have a chamber section oriented toward the measuring membrane and a rear wall section oriented away from the measuring membrane with, between these, a decoupling chamber. The chamber sections each have an equalizing duct between the measuring chamber and the decoupling chamber, wherein the decoupling chamber has a diameter that is at least as large as the diameter of the measuring chamber.

First claim

The invention claimed is:

1. A differential pressure measuring cell, comprising:
a measuring membrane;
a first opposing body;
a second opposing body; and
a converter, said converter converting a deformation of said measuring membrane, which deformation is dependent upon a difference between said first pressure and said second pressure, into an electrical signal;
wherein:
said measuring membrane is arranged between said first opposing body and said second opposing body and is connected in a pressure-tight manner to said two opposing bodies;
a first measuring chamber is formed between said measuring membrane and said first opposing body; and
a second measuring chamber is formed between said measuring membrane and said second opposing body, and
wherein:
said first opposing body and said second opposing body each have a pressure duct through which the first pressure or the second pressure can be applied to said respective measuring chamber;
at least one of the opposing bodies has a chamber section oriented toward said measuring membrane and a rear wall section oriented away from said measuring membrane; a decoupling chamber is provided between said chamber section and rear wall section; said chamber section has at least one equalizing duct by means of which said measuring chamber communicates with said decoupling chamber; and said decoupling chamber has, in a plane parallel to said measuring membrane, a diameter that is at least as large as the diameter of said measuring chamber, and
the differential pressure measuring cell further comprises: at least one additional electric converter for determining a static pressure, which is applied to the differential pressure measuring cell, at least based upon a pressure-dependent deformation of said rear wall section.

2. The differential pressure measuring cell according to claim 1 , wherein:
a surface of said chamber section has an annular circumferential relief groove, said surface being oriented toward said decoupling chamber.

3. The differential pressure measuring cell according to claim 1 , wherein:
a surface of said rear wall section has an annular circumferential relief groove, said surface being oriented toward said decoupling chamber.

4. The differential pressure measuring cell according to claim 1 , wherein:
the volume stroke of said decoupling chamber ΔV E =V E (p stat )−V E (p 0 ), in case of a loading of said first measuring chamber and said second measuring chamber with the same static pressure p stat , is at least as large as the volume stroke of said measuring chamber communicating with said decoupling chamber via the equalizing duct ΔV M =V M (p stat )−V M (p 0 ), where p 0 is an equilibrium pressure, in case of which the same pressure prevails inside and outside the differential pressure measuring cell.

5. The differential pressure measuring cell according to claim 1 , wherein:
the volume stroke of said decoupling chamber ΔV E is at least double, and especially not less than four times, the volume stroke of said measuring chamber communicating with said decoupling chamber via the equalizing duct ΔV M .

6. The differential pressure measuring cell according to claim 1 , wherein:
at least one of said chamber sections has a membrane bed oriented toward said measuring membrane, which membrane bed supports said measuring membrane in case of a unilateral overload pressure.

7. The differential pressure measuring cell according to claim 6 , wherein:
said membrane bed has a contour that approximates a bending line of said measuring membrane at a unilateral limit pressure, so that said measuring membrane is supported by said membrane bed when this limit pressure is reached.

8. The differential pressure measuring cell according to claim 3 , wherein:
said chamber section and said rear wall section are connected to one another in a pressure-tight manner by means of a circumferential opposing body joint; and
a maximum stress in the opposing body joint is less than a maximum stress in said rear wall section when pressure is applied to the differential pressure measuring cell.

9. The differential pressure measuring cell according to claim 8 , wherein:
the maximum stress in said rear wall section is adjacent to the relief groove;
said relief groove has a depth of not less than 0.1 mm; and
the location of the maximum stress in said rear wall section is spaced apart from the joint by at least half the depth of said relief groove, and preferably by at least the depth of said relief groove.

10. The differential pressure measuring cell according to claim 8 , wherein:
said measuring membrane is respectively connected to the opposing bodies along a circumferential membrane joint; and
a maximum stress in said membrane joint is smaller than the maximum stress in said opposing body joint when the same static pressure p stat is applied to said first measuring chamber and said second measuring chamber.

11. The differential pressure measuring cell according to claim 1 , wherein:
said measuring membrane and/or said chamber section and/or said rear wall section feature a ceramic material, especially corundum.

12. The differential pressure measuring cell according to claim 10 , wherein:
the joints have an active hard solder, especially a Zr—Ni—Ti-containing active hard solder.

13. The differential pressure measuring cell according to claim 1 , wherein:
said additional electric converter comprises a capacitive converter that has a first electrode on one of the end surfaces of said rear wall section, which end surface is oriented toward said decoupling chamber, and a second electrode on one of the end surfaces of said chamber section, which end surface is oriented toward said decoupling chamber.

Assignees

• Endress Hauser Gmbh Co Kg
• Endress Hauser Se Co Kg

Inventors

• Drewes Ulfert
• Hugel Michael
• Ponath Nils
• Rossberg Andreas
• Schmidt Elke
• Uehlin Thomas

Classifications

• G01L19/0618 Primary

  Overload protection · CPC title

• G01L13/025

  using diaphragms · CPC title

• G01L15/00

  Devices or apparatus for measuring two or more fluid pressure values simultaneously · CPC title