Pressure sensing vessel adapted to be preloaded against a sensor

• US 5,563,347 A
• Filed: 09/12/1994
• Issued: 10/08/1996
• Est. Priority Date: 09/12/1994
• Status: Expired due to Term

• Current Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Original Assignee: IVAC Holdings, Inc. (River Acquisition Corp.)
• Inventors: Clemens, Charles E., Martin, Stephen A., Butterfield, Robert D.
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/305,465
• Time in Patent Office: 757 Days
• Field of Search: 73/756, 73/715, 73/716, 73/706, 73/708, 73/721, 73/727
• US Class Current: 73/756
• CPC Class Codes: G01L 19/14 Housings G01L19/0007, G01L19/0084, G01L19/0092, G01L19/04, G01L19/06 take precedence

Abstract

A pumping segment for incorporation into a fluid delivery system, the segment having a dome-shaped pressure vessel with an optimal shape for interfacing with a pressure sensing element, and which is capable of uniformly distributing pressure across its interfacing structure and being optimally pre-loaded against the pressure sensing element. The pumping segment including a lateral restraint to inhibit rupture of the unloaded pressure vessel when experiencing high internal pressures.

Claims

1. In a segment for fluid flow, a pressure vessel for interfacing with a sensor having a sensor surface for pressing against the pressure vessel and establishing a pre-load with the pressure vessel and for transferring fluid pressure of the segment to the sensor, the pressure vessel comprising:

a hollow crown for engaging the sensor, having a cylindrical side wall, a closed upper end for pressing against the sensor surface and an open lower end formed of a flexible material, within which the fluid pressure is received, the crown portion adapted to be pre-loaded against the sensor surface so that both positive and negative pressures of the fluid pressure within the segment will be communicated to the sensor; and

a membrane peripheral region connected to and extending away from the open lower end of said hollow crown, the peripheral portion suspending the crown so that the crown moves in response to fluid pressure and biasing the crown into contact with the sensor surface to establish the pre-load.

2. The segment of claim 1, wherein said membrane peripheral portion is adapted to be retained by stationary structure, thereby allowing said membrane peripheral portion to perform as a flat washer spring for said crown portion of the pressure vessel.

3. The segment of claim 2 wherein:

said stationary structure comprises a lateral restraint configured to limit the lateral movement of the side wall in response to fluid pressure.

4. The segment of claim 3 wherein the lateral restrain is disposed completely around the cylindrical side wall of the hollow crown portion and is configured to limit the amount of lateral movement of the side wall in response to internal fluid pressure.

5. The segment of claim 1, wherein said closed upper end includes:

a rim region defined by the top of said cylindrical sidewall, said rim region being substantially perpendicular to said sidewall; and

a center dome region connected to said rim region, said rim region and said center dome region defining a top of said crown portion.

6. The segment of claim 5, wherein said top of said center dome region has a pre-determined contour adapted to uniformly distribute stresses across its face when applied to the pressure sensor.

7. The segment of claim 1 further comprising:

a lateral restraint configured to limit the lateral movement of the side wall in response to fluid pressure.

8. The segment of claim 7 wherein the lateral restrain is disposed completely around the cylindrical side wall of the hollow crown portion and is configured to limit the amount of lateral movement of the side wall in response to internal fluid pressure.

9. A pressure vessel, in fluid communication with a conduit, for transferring pressure of a fluid contained within the conduit to a sensor having a sensor surface that presses against the pressure vessel to establish a predetermined pre-load so that both reduced and increased pressures of the fluid in the conduit can be detected by the sensor, the pressure vessel comprising:

a hollow crown shaped for direct contact with the sensor surface and disposed so that the hollow portion receives fluid pressure of the fluid contained within the conduit, the hollow crown having a closed top for direct contact with the sensor surface and a side wall; and

a resiliently deformable peripheral region extending from a bottom portion of the side wall of the hollow crown that suspends the crown such that the crown is movable toward and away from the sensor surface in response to the fluid pressure.

12. The pressure vessel of claim 9 wherein the peripheral region extends radially outwardly from the bottom of the side wall.

13. The pressure vessel of claim 9 wherein the side wall is cylindrical and is disposed perpendicular to the closed top of the crown.

14. The pressure vessel of claim 13 wherein the cylindrical side wall is sufficiently stiff to prevent it from buckling while undergoing the predetermined pre-load with the sensor surface and while undergoing a predetermined range of increased and reduced pressures of the fluid.

15. The pressure vessel of claim 9 further comprising a lateral restraint that is disposed about the crown to limit lateral deflection of the crown.

16. The pressure vessel of claim 15 wherein the lateral restraint is spaced outwardly from the crown by a distance selected to prevent engagement between the crown and the lateral restraint during exposure of the crown to a predetermined range of pressures of the fluid but to engage and support the crown when the pressure of the fluid exceeds the predetermined range.

17. The pressure vessel of claim 16 wherein the lateral restrain comprises a rigid member having an opening within which the crown is disposed, the side of the opening limiting the lateral movement of the side wall.

18. The pressure vessel of claim 17 wherein the side of the opening comprises a chamfer facing the side wall of the crown, the size and location of the chamfer selected so that the peripheral region may move freely during a predetermined range of fluid pressure while the side of the opening restrains the side wall of the crown.

19. The pressure vessel of claim 9 wherein the dosed top of the hollow crown has a domed contour with the contour selected such that the top flattens against the sensor surface under conditions of the pre-load and exposure to a predetermined range of fluid pressures so that uniform stress distribution across the top of the crown is generated by the fluid pressure whereby substantially the same pressure is transmitted to the sensor surface at all portions of the closed top of the crown.

20. The pressure vessel of claim 19 wherein the closed top of the crown has a diameter that is at least twice as large as the sensor surface whereby lateral displacement of the crown during mounting of the crown to the sensor surface is tolerated.

10. The pressure vessel of claim herein the peripheral region biases the crown towards the sensor surface to establish the predetermined pre-load.

11. The pressure vessel of claim 10 wherein the size of the side wall and the amount of bias provided by the peripheral region are selected to establish a pre-load with the sensor surface that exceeds a predetermined maximum lift-off force that may be generated by reduced pressure of the fluid within the conduit.

21. A pressure vessel, in fluid communication with a conduit, for transferring pressure of a fluid contained within the conduit to a sensor having a sensor surface that presses against the pressure vessel to establish a predetermined pre-load so that both reduced and increased pressures of the fluid in the conduit can be detected by the sensor, the pressure vessel comprising:

a hollow crown shaped for direct contact with the sensor surface and disposed so that the hollow portion receives fluid pressure of the fluid contained within the conduit, the hollow crown having a closed top for direct contact with the sensor surface and a cylindrical side wall perpendicular to the closed top;

a resiliently deformable peripheral region extending radially outwardly from a bottom portion of the side wall of the hollow crown that suspends the crown such that the crown is movable toward and away from the sensor surface in response to the fluid pressure, and that biases the crown toward the sensor surface;

a lateral restraint disposed outwardly from the crown by a distance selected to prevent engagement between the crown and the lateral restraint during exposure of the crown to a predetermined range of pressures of the fluid but to engage and support the crown when the pressure of the fluid exceeds the predetermined range;

wherein the size of the side wall and the amount of bias provided by the peripheral region are selected to establish a pre-load with the sensor surface that exceeds a predetermined maximum lift-off force that may be generated by reduced pressure existing within the conduit and wherein the cylindrical side wall is sufficiently stiff to prevent it from buckling while undergoing the predetermined pre-load with the sensor surface and while undergoing the predetermined range of increased and reduced pressures of the fluid.

22. The pressure vessel of claim 21 wherein the closed top of the hollow crown has a domed contour with the contour selected such that the top flattens against the sensor surface under conditions of the pre-load and exposure to the predetermined range of fluid pressures so that uniform stress distribution across the top of the crown is generated by the fluid pressure whereby substantially the same pressure is transmitted to the sensor surface at all portions of the closed top of the crown.

23. The pressure vessel of claim 22 wherein the closed top of the crown has a diameter that is at least twice as large as the sensor surface whereby lateral displacement of the crown during mounting of the crown to the sensor surface is tolerated.

24. The pressure vessel of claim 22 wherein the lateral restrain comprises a rigid member having an opening within which the crown is disposed, the side of the opening limiting the lateral movement of the side wall.

25. The pressure vessel of claim 24 wherein the side of the opening comprises a chamfer facing the side wall of the crown, the size and location of the chamfer selected so that the peripheral region may move freely during a predetermined range of fluid pressure while the side of the opening restrains the side wall of the crown.