Pressure transmitter with high pressure isolator mounting assembly

• US 6,050,145 A
• Filed: 07/10/1997
• Issued: 04/18/2000
• Est. Priority Date: 04/28/1995
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Bischoff, Brian J., Olson, Mark H., Moser, Thomas M., Jost, Michael B.
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US08/891,244
• Time in Patent Office: 1,013 Days
• Field of Search: 73/706, 73/721, 73/727, 73/756
• US Class Current: 73/706
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 19/0636 using particle filters
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/0663 Flame protection; Flame barriers
• CPC Class Codes: G01L 19/143 Two part housings
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation

Abstract

A pressure transmitter includes an isolator mounting assembly for isolating process fluid from an interior cavity of the pressure transmitter. The isolator mounting assembly includes an isolator plug for receiving the process fluid line pressure and coupling the line pressure to a sensor cavity formed by a header joined to a distal end of the plug. A ring member is attached to the header and the distal end of the plug to reinforce the joint formed between the isolator plug and the head. In another embodiment, the isolator mounting assembly includes a base and a support having first and second opposed ends. The first end is rigidly bonded to the pressure sensor while an epoxy joint joins the second end of the support to the base.

Claims

1. A transmitter connectable to a process line and providing an output responsive to a pressure in the process line, the transmitter comprising:

a housing forming a wall around a hole extending into an interior cavity formed in the housing;

a sensor for sensing the pressure;

a circuit coupled to the sensor and providing the output; and

an isolating assembly mounted in the hole isolating fluid in the process line from the interior cavity, the isolating assembly comprising;

an isolator plug insertable into a process fluid passage and joined to the housing, the isolator plug having first and second spaced end surfaces, the first end surface forming a process fluid pressure surface and, having a diaphragm coupling the pressure via a passageway to a distal end of the plug;

a header assembly joined to the second end surface of the plug to form a sensor cavity holding the sensor and receiving the pressure from the passageway;

a first connection between the header assembly and the second end surface of the plug to secure the header assembly to the plug;

a second connection between the header assembly and the second end surface of the plug to secure the header assembly to the plug;

the header assembly including a header and a ring member joined to the header, the first connection being formed on the header and the second connection being formed on the ring member to secure the header assembly to the plug.

2. The transmitter of claim 1 wherein the first connection is an annular weld that joins the header to the second end surface of the plug, and the second connection is a second annular weld that joins the ring member to the header and a third annular weld joins the ring member to the isolator plug.

3. The transmitter of claim 1 and a connector having a bore extending from a first end to a second end, and the isolator includes first and second plug portions, the first plug portion including an outer surface having a first outer dimension sized for insertion into the hole formed in the housing and the second plug portion including a second outer surface having a second outer dimension for insertion into the bore of the connector and the isolator plug including a stepped surface between the first and second portions, the connector being connectable to the process line at the first end and joined to the stepped surface of the isolator plug at the second end.

4. The transmitter of claim 3 and an annular weld joining the second end of the connector to the plug.

5. The transmitter of claim 1 and a second passageway extending through the header, the second passageway coupling a second pressure to the sensor.

6. The transmitter of claim 5 and a recess formed between opposed surfaces of the header and the ring member, the recess opening to the second passageway and coupling the second pressure.

7. The transmitter of claim 5 and a third passageway formed in the plug and fluidically communicating with the second passageway.

8. The transmitter of claim 7 wherein the wall threadably engages the plug along a threaded portion, and wherein the third passageway has an opening remote from the threaded portion.

9. The transmitter of claim 8 and a filter material located in the third passageway.

10. The transmitter of claim 5 and a tube joined at a first end to the header about an opening of the second passageway with an epoxy, the tube supporting the sensor in the sensor cavity and coupling the second pressure to the sensor.

11. A transmitter connectable to a process line and providing an output responsive to a process pressure in the process line with respect to atmospheric pressure, the transmitter comprising:

a housing forming an inner wall around a hole extending into an interior cavity formed in the housing;

a sensor for sensing the pressure;

a circuit coupled to the sensor and providing the output;

an isolator plug disposed in the hole having;

a diaphragm therein coupling the process pressure via a first passageway to a distal end of the plug; and

a second passageway extending from a first surface to a second surface for carrying atmospheric pressure to the sensor.

13. The transmitter of claim 11 and further comprising:

a header joined to the distal end of the plug to form a sensor cavity holding the sensor and receiving the process pressure from the first passageway, the header including a third passageway for carrying atmospheric pressure to the sensor; and

a ring member joined to the isolator plug and the header and forming a recess opening to the second passageway and the third passageway for carrying the atmospheric pressure.

14. The transmitter of claim 13 and further comprising:

a tube having a first end bonded to the pressure sensor and a second end opening to the third passageway for carrying the atmospheric pressure; and

an elastic joint between the second end of the support and the header, the elastic joint including a material selected from the group consisting of an epoxy, a polyimide and a polyurethane.

15. The transmitter of claim 14 wherein the tube comprises glass and the second end has a bonding surface consisting essentially of a glass.

16. The transmitter of claim 15 wherein an anodic bond joins the first end to the pressure sensor.

17. The transmitter of claim 11 wherein the isolator plug includes a portion joined to the inner wall, the portion being disposed between the first surface and the second surface.

18. The transmitter of claim 17 wherein the second passageway opens to the hole.

19. The transmitter of claim 13 wherein the recess opening comprises an annular recess formed about the header.

20. The transmitter of claim 19 wherein the recess comprises an inner annular groove formed in the ring member.

21. The transmitter of claim 11 wherein the second passageway comprises a flame arresting path.

22. The transmitter of claim 13 wherein the third passageway comprises a flame arresting path.

12. A transmitter connectable to a process line and providing an output responsive to a pressure in the process line, the transmitter comprising:

a housing forming a wall around a hole extending into an interior cavity formed in the housing;

an isolating assembly mounted in the hole isolating fluid in the process line from the interior cavity, the isolating assembly comprising;

an isolator plug, the isolator plug having a diaphragm for receiving the pressure;

a connector having a bore extending between first and second spaced ends of the connector;

the isolator plug including first and second plug portions,

the first plug portion including a first outer surface having a first outer dimension sized for insertion into the hole formed in the housing and engagement with the wall surrounding the hole; and

the second plug portion including a second outer surface having a second outer dimension sized smaller than the first outer dimension for insertion into the bore of the connector; and

the isolator plug including a stepped surface between the first and second plug portions, the stepped surface having a first mating surface surrounding a first groove, the connector having a second mating surface surrounding a second groove, the connector being disposed such that the first and second grooves open to each other; and

an annular weld joining the first mating surface to the second mating surface.

23. A transmitter connectable to a process line and providing an output responsive to a pressure in the process line, the transmitter comprising:

a housing forming an inner wall around a hole extending into an interior cavity formed in the housing;

an isolator plug, the isolator plug having a diaphragm therein coupling the pressure via a passageway from a diaphragm end to a sensor end thereof;

a connector having a bore extending from a first end to a second end;

the isolator plug including;

first and second plug portions, the first plug portion including a first outer surface having a first outer dimension sized for insertion into the hole formed in the housing and engagement with the wall surrounding the hole, and the second plug portion including a second outer surface having a second outer dimension sized smaller than the first outer dimension for insertion into the bore of the connector; and

a stepped surface between the first and second portions;

the connector connectable to the process line at the first end and secured to the stepped surface of the isolator plug at the second end;

an annular weld securing the isolator plug to the connector;

a sensor for sensing the pressure; and

a circuit coupled to the sensor and providing the output.

24. The transmitter of claim 23 wherein the isolator plug includes a mating portion mating with the inner wall, the mating portion disposed between the diaphragm end and the sensor end.

25. The transmitter of claim 24 wherein the annular weld is disposed between mating portion and the diaphragm end.

26. The transmitter of claim 23 wherein the connector is spaced-apart from the inner wall.

27. The transmitter of claim 23 wherein annular weld joins a first mating surface of the isolator plug with a second mating surface of the connector, and wherein the first mating surface includes a first groove disposed inwardly from the annular weld and the second mating surface includes a second groove disposed inwardly from the annular weld, and wherein the first and second grooves open to each other.

28. The transmitter of claim 23 wherein the isolator plug includes an extending portion disposed between the annular weld and the diaphragm end.

29. The transmitter of claim 28 wherein the extending portion includes a first set of threads, and wherein the connector includes a second set of threads that mate with the first set of threads on the extending portion.

30. The transmitter of claim 23 and further comprising:

a ring member joined to the isolator plug and the header.

31. The transmitter of claim 30 wherein a second annular weld joins the header to the sensor end of the plug, a third annular weld joins the ring member to the header and a fourth annular weld joins the ring member to the isolator plug, and wherein the first-mentioned annular weld is larger than the second annular weld.