Pressure measuring device

• US 5,886,268 A
• Filed: 10/08/1997
• Issued: 03/23/1999
• Est. Priority Date: 04/11/1995
• Status: Expired due to Term

• Current Assignee: Malvern Instruments, Ltd. (Spectris PLC)
• Original Assignee: Reologica Instruments AB (Spectris PLC)
• Inventors: Larsson, Sven-Erik
• Primary Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/930,807
• Time in Patent Office: 531 Days
• Field of Search: 73/862.581-862.584, 73/862.49
• US Class Current: 73/862.583
• CPC Class Codes: G01L 1/083 using hydraulic or pneumatic counterbalancing forces
• CPC Class Codes: G01L 5/12 for measuring axial thrust in a rotary shaft, e.g. of propulsion plants
• CPC Class Codes: G01N 11/10 by moving a body within the material
• CPC Class Codes: G01N 2203/0226 High temperature; Heating means
• CPC Class Codes: G01N 3/06 Special adaptations of indicating or recording means

Abstract

A method for measurement of axial forces acting on a shaft, being supplied with gas under overpressure such that gas pressure is built up between two opposing faces of said portion projecting radially from the shaft and at least one gas-permeable body provided external to said faces. A gas differential between the gas pressure on said opposing faces is established, and the axial force acting on said shaft is determined as a product of a constant and the pressure differential between the gas pressures on the two faces. Means are provided for supply of gas under overpressure to said body and pressure measuring means are provided for measurement of the pressure differential between the pressures on the two faces of the radially projecting portion. The protruding portion may also constitute a measuring plate which, provided in various manners, is subjected to forces.

Claims

1. A method for measurement of forces acting axially on a shaft, said shaft having a portion protruding from said shaft, said portion having a first and second opposing side, comprising the steps of:

supplying gas under overpressure; and

providing at least one gas-permeable body outside of at least one of said opposing sides,

wherein a gas pressure is built up between at least one of said opposing sides of said portion protruding from the shaft and a gas pressure on at least one of said opposing sides is measured and that the force acting axially on the shaft is determined as a function of the measured gas pressure.

2. The method according to claim 1, wherein a pressure differential is measured between the gas pressures on said opposing sides and that the force acting axially on said shaft is determined as k*Δ

P, with k being a constant and Δ

P being the pressure differential between the gas pressures on said opposing sides.

3. A measuring device comprising:

a rotative shaft for measurement of axial forces acting on a shaft,

at least one gas-permeable body positioned on the outside of said shaft with a column standing under pressure between the outer envelope surface of the shaft and said body;

a protruding portion protruding from said shaft extending through said body with play, said protruding portion having two axially opposing sides;

means for supplying gas under overpressure to said body; and

pressure measuring means for measurement of pressure on at least one of said two sides of said protruding portion,

wherein the force acting on said shaft is a function of the measured pressure.

4. The measuring device according to claim 3 further comprising:

a plurality of second channels extending axially in said body, each of said channels having an outlet directed axially toward said two opposing sides of said protruding portion and said second channels are connected to said pressure measuring means.

5. The measuring device according to claim 4, wherein said body is surrounded by a sealed casing.

6. The measuring device according to claim 5, wherein said body comprises at least one porous, gas-permeable sleeve.

7. The measuring device according to claim 5, wherein said shaft has a first end connected to a first measuring body with a test medium for measurement of the viscoelastic properties of said test medium.

8. The measuring device according to claim 7, wherein said test medium is enclosed in a test chamber, which is defined by said second measuring body and said column, the over pressure of said column causing the test medium to be put under pressure.

9. The measuring device according to claim 5, wherein said body is connected to a first mounting plate, said shaft is connected to a second mounting plate and said first mounting plate and said second mounting plate are movable relative to each other in the axial direction of said shaft.

10. A method for measurement of radial forces acting on a shaft comprising the steps of:

supplying the outer envelope surface of said shaft with gas under overpressure, gas pressure is built up in a space between the envelope surface and at least one gas-permeable body adjacent to the envelope surface;

measuring a first pressure differential between said gas pressure on two radially opposing first portions of said space; and

measuring a second pressure differential between gas pressure on two radially opposing second portions of said space, said first and second portions being provided perpendicularly to each other,

wherein the resulting pressure differential is determined as the difference between said first and second pressure differentials, and the radial force acting on said shaft is determined as k*Δ

P, with k being a constant and Δ

P being the resulting pressure differential.

11. A method for measurement of forces comprising the steps of:

supplying at least one of two opposing faces of a measuring plate with gas under overpressure such that gas pressure is built up between at least one of said two opposing faces and at least one gas-permeable body provided external to said opposing faces; and

measuring gas pressure on at least one of said opposing faces,

wherein the force acting on one of said faces is determined as a function of the measured gas pressure.

12. The method for measurement of forces according to claim 11, wherein said two opposing faces of a measuring plate are supplied with gas under overpressure in such a way that gas pressure is built up between said two opposing faces and at least one gas-permeable body external to said opposing faces, gas pressure between the gas pressures on said opposing faces is established and the force acting on one of said faces is determined as k*Δ

P, with k being a constant and Δ

P being the pressure differential between the gas pressures on said two opposing faces.

13. The method according to claim 12, wherein said gas is supplied through the gas-permeable body.

14. The method according to claim 12, wherein said gas is supplied to the gas-permeable body through open chambers.

15. A measuring device for measurement of forces on a measuring plate comprising;

said measuring plate provided with at least one body having at least one of two opposing faces of said measuring plate turned toward gas-permeable surfaces of the body;

means for supplying gas under overpressure to said body; and

pressure measuring means for measurement of gas pressure on at least one of the two faces of the measuring plate,

wherein the force acting on the measuring plate is a function of the measured gas pressure.

16. The measuring device according to claim 15, wherein said measuring plate is provided in said turned toward gas-permeable surfaces of the body, said pressure measuring means are provided for measurement of the pressure differential between the pressures on said two faces of the measuring plate, the pressure differential constituting a measure for the force acting on the measuring plate.

17. The measuring device according to claim 16, wherein said measuring plate is rigidly connected to and protruding from a shaft, said shaft being subjected to a torque.

18. The measuring device according to claim 16, wherein said measuring plate protrudes in the radial direction of said shaft.

19. The measuring device according to claim 16, wherein a portion of said measuring plate protruding from said body is articulated connected with a support device fixed relative to said body.