Pressure measuring device with free-standing carrier

Patent metadata

Field	Value
Publication number	US-11754455-B2
Application number	US-201917277864-A
Country	US
Kind code	B2
Filing date	Sep 5, 2019
Priority date	Sep 19, 2018
Publication date	Sep 12, 2023
Grant date	Sep 12, 2023

Abstract

A pressure measuring device includes a ceramic pressure sensor and a process connection, the pressure sensor including a measuring membrane. The pressure measuring device further includes a carrier made of titanium and having a free-standing tubular carrier region running parallel to the surface normal onto the measuring membrane and having an end region adjacent the process connection connected to the process connection and an end region opposite the process connection to which the pressure sensor is fastened by a jointing that connects an outer edge of a front face of the pressure sensor to the end region of the carrier opposite the process connection and carries the pressure sensor.

First claim

The invention claimed is:

1. A pressure measuring device, comprising:
a ceramic pressure sensor including a measuring membrane having a surface normal, wherein the ceramic pressure sensor is structured to enable the measuring membrane to be subjected to a pressure to be measured;
a process connection configured to enable the pressure measuring device to be mounted on a connection complementary thereto and/or to be connected to a connection of a differential pressure line complementary thereto; and
a carrier including a free-standing, tubular support region running parallel to the surface normal of the measuring membrane, a first end region adjacent and connected to the process connection, and a second end region opposite the process connection to which the ceramic pressure sensor is attached via a first joint, which connects an outer edge of an end face of the ceramic pressure sensor to the second end region of the carrier and which supports the ceramic pressure sensor,
wherein the carrier is made of titanium.

2. The pressure measuring device of claim 1 , wherein the carrier is configured as a tube disposed in a free-standing manner on the process connection, which comprises the support region, an end region of which is the second end region of the carrier opposite the process connection and connected via the first joint to an outer edge of a front end face of the ceramic pressure sensor defined by the measuring membrane.

3. The pressure measuring device of claim 1 , wherein:
the measuring membrane is connected to a main body of the ceramic pressure sensor, thereby enclosing a pressure chamber;
the second end region of the carrier includes a radially inwardly extending shoulder that, at its proximal end, adjoins the support region; and
an outer edge of a rear end face of the ceramic pressure sensor defined by the main body is connected via the first joint to an inner edge region of an inner side of the shoulder, which faces the process connection, the inner edge region being spaced apart from the support region.

4. The pressure measuring device of claim 3 , wherein in a direction parallel to the surface normal of the measuring membrane, the support region has a length that is greater than or equal to a structural height of the ceramic pressure sensor in the direction parallel to the surface normal of the measuring membrane.

5. The pressure measuring device of claim 3 , wherein the process connection is made of a stainless steel, and/or
wherein the measuring membrane and/or the main body of the ceramic pressure sensor are both made of aluminum oxide (Al 2 O 3 ) or of another oxide ceramic.

6. The pressure measuring device of claim 1 , wherein the process connection includes a pressure transmission path extending through the process connection and opening into a pressure receiving chamber upstream of the measuring membrane and sealed in a diffusion-tight manner and by which the pressure to be measured is applied to the measuring membrane.

7. The pressure measuring device of claim 1 , wherein the support region of the carrier, in a direction parallel to a longitudinal axis to the measuring membrane, has a length greater than its wall thickness, and/or the wall thickness of the support region of the carrier is 1 mm to 2 mm.

8. The pressure measuring device of claim 1 , wherein the ceramic pressure sensor is configured as a free-standing pressure sensor, which is attached only via the first joint connecting the edge of the end face of the ceramic pressure sensor to the carrier.

9. The pressure measuring device of claim 1 , further comprising a housing mounted on the process connection, which surrounds the carrier, the ceramic pressure sensor and measuring electronics connected to the ceramic pressure sensor, the housing is spaced apart from the carrier and from the ceramic pressure sensor.

10. The pressure measuring device of claim 1 , wherein an end face of the first end region of the carrier is connected directly to the process connection via a second joint, or
wherein the first end region of the carrier is connected to the process connection in a diffusion-tight manner via at least one interposed further component arranged between the carrier and the process connection in a direction parallel to the surface normal to the measuring membrane.

11. The pressure measuring device of claim 1 , wherein the first joint connecting the ceramic pressure sensor to the carrier is formed by a hard solder, wherein the hard solder is free of active components usable for active brazing, and wherein the first joint is formed by a joining method in which:
joining surfaces of the carrier and the ceramic pressure sensor seat against each other via the interposed hard solder; and
the hard solder is selected such that, when heated to a joining temperature at which the hard solder is melted, a portion of the titanium in the carrier diffuses through the melted hard solder, which is in contact with the carrier, to the ceramic of the ceramic pressure sensor and reacts with the ceramic such that a chemical compound comprising titanium is formed.

12. The pressure measuring device of claim 11 , wherein the hard solder comprises:
silver and copper;
silver, copper and further, non-active component;
silver copper indium; or
tin silver copper, or
wherein the hard solder consists of silver and copper.

13. The pressure measuring device of claim 11 , wherein the carrier is connected to the process connection, or a component made of stainless steel disposed between the carrier and the process connection, by a second joint configured as either a welded joint or as a hard solder joint, wherein the hard solder either:
is identical to the hard solder of the first joint connecting the ceramic pressure sensor to the carrier, or has a melting temperature substantially the same as a melting temperature of the hard solder of the first joint; or
has a melting temperature lower than a melting temperature of the hard solder of the first joint and/or is a copper silver hard solder having a relatively higher copper content and a relatively lower silver content than the hard solder of the first joint.

14. A method for producing a pressure measuring device according to claim 1 , the method comprising:
providing the ceramic pressure sensor, the carrier and the process connection as prefabricated, individual parts;
connecting the ceramic pressure sensor to the carrier by performing a joining method by which the first joint connecting the ceramic pressure sensor to the carrier is formed; and
mounting the carrier on the process connection.

15. The method of claim 14 , wherein the first joint is formed of a hard solder that is free of active components usable for active brazing, and
wherein the joining method includes:
providing an arrangement in which the joining surfaces of the carrier and the ceramic pressure sensor rest against each other via the hard solder therebetween; and
heating the arrangement to a joining temperature at which the hard solder is melted such that a portion of the titanium contained in the carrier diffuses through the melted hard solder to the ceramic of the ceramic pressure sensor and reacts there with the ceramic such that a chemical compound comprising titanium is formed.

Assignees

• Endress Hauser Se Co Kg

Inventors

• Ponath Nils
• Rossberg Andreas
• Schmidt Elke

Classifications

• G01L19/147 Primary

  Details about the mounting of the sensor to support or covering means · CPC title

• G01L19/04 Primary

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• G01L9/0075

  using a ceramic diaphragm, e.g. alumina, fused quartz, glass · CPC title