GB1599339A - Device for the measurment of forces or pressures - Google Patents
Device for the measurment of forces or pressures Download PDFInfo
- Publication number
- GB1599339A GB1599339A GB9779/78A GB977978A GB1599339A GB 1599339 A GB1599339 A GB 1599339A GB 9779/78 A GB9779/78 A GB 9779/78A GB 977978 A GB977978 A GB 977978A GB 1599339 A GB1599339 A GB 1599339A
- Authority
- GB
- United Kingdom
- Prior art keywords
- load cell
- resistive element
- low shear
- shear force
- strain gauge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000463 material Substances 0.000 claims description 27
- 239000004020 conductor Substances 0.000 claims description 18
- 238000005259 measurement Methods 0.000 claims description 7
- 239000011810 insulating material Substances 0.000 claims description 6
- 229920001971 elastomer Polymers 0.000 claims description 5
- 229910000896 Manganin Inorganic materials 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 230000001419 dependent effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 238000009530 blood pressure measurement Methods 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims description 2
- 238000006073 displacement reaction Methods 0.000 claims description 2
- 229920002379 silicone rubber Polymers 0.000 claims description 2
- 238000012360 testing method Methods 0.000 claims description 2
- 238000012546 transfer Methods 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
- G01L9/0002—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using variations in ohmic resistance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0089—Transmitting or indicating the displacement of pistons by electrical, electromechanical, magnetic or electromagnetic means
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Measurement Of Force In General (AREA)
Description
(54) DEVICE FOR THE MEASUREMENT OF FORCES OR PRESSURES
(71) We, BETRIEBSFORSCHUNG
SINSTITUT VDEH INSTITUT FUR
ANGEWANDTE FORSCHUNG GMBH.
a Germany company of 4000 Dusseldorf,
Sohnstrasse 65, West Germany. do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement:
This invention relates to a device for measuring forces and pressures, and more particularly to such a device which includes a metal wire whose specific resistance is highly pressure sensitive and which is embedded in a low shear force material (such as flexible rubber) which can be compressed within a load cell by means of a movable piston.
A device of this type is disclosed in
German Offenlegungsschrift 23 33 503.7, in which the metal wire (preferably constructed from manganin) is extensively arranged equally on the bearing surfaces, more particularly in a meander-shaped disposition. The load cell is drilled transversely to the loading direction at two points for the passage of the ends of the wire therethrough, the holes thus drilled being of such a diameter that the connecting ends of the wire can be passed laterally therethrough in an insulated condition in order to allow further connections to be made to the wire outside the load cell. Such a device, however, requires that part of the measuring wire remains pressure-free during measurement.
It is an object of the present invention to provide a device for measuring forces and pressures in which this requirement can be avoided.
According to one aspect of the invention, there is provided a device for measuring forces and pressures, comprising a load cell including a low shear force material, a piston movable so as to apply the force or pressure to be measured to the low shear force material, a resistive element whose specific resistance is pressure-dependent embedded in the low shear force material so that all of the resistive element is subjected to the force or pressure applied to the low shear force material by the piston, and a sheathed thermocouple element including a pair of conductors which are mutually insulated and connected to the ends of the resistive element respectively, the sheathed thermocouple element being led out of the load cell.
In this way, the whole of the resistive element can be exposed to the force of pressure to be measured, and the execution of the measurement can be simplified.
Sheathed thermocouple elements are already basically known as for instance from "The Handbook of Technical Temperature
Measurement", 1976, page 80 by Fritz
Lieneweg. In the present invention, one conductor of the thermocouple is constituted by the sheath, the other conductor being disposed within the sheath and insulated therefrom by highly compressed powder-form oxide insulation material, such as magnesium or aluminium oxide. Designs are also admissable in which both conductors are suitably insulated within a sheath.
The points at which the insulated conductor(s) project from the ends of the sheath are preferably separately sealed in a conventional manner, for instance by means of synthetic resin. The outer ends of the conductors can be connected in a known manner to connector heads or plugs. On the other hand, the inner ends thereof are preferably connected to the resistive element by cold-compacting or brazing.
The sheathed thermocouple element preferably extends sideways out of the load cell transversely to the direction of application of the force or pressure to be measured in use. This has the advantage of allowing the complete load cell to be made unusually flat.
The sheathed thermocouple element preferably has an external diameter of between 0.15 and 3 mm. The cross-section which the opening (provided in particular laterally inside the load cell) must have for passage of the sheathed thermocouple element is thus unusually limited, so that even the greatest forces produced within the load cell result only in very limited displacement forces.
The result is that the transfer of internal forces from the load cell is extensively free from loading.
The forces and pressures to be measured by means of the device frequently have a strong dynamic pattern. Minimal movements of the thermocouple conductors where these extend inside the load cell cannot be avoided, with the result that the insulating compound is subject to additional shifting in relation to the sheath. Expulsion of the insulating material from the free end of the thermocouple element can be avoided in a simple manner by ensuring that the thermocouple element is curved at its exit from, as well as inside, the load cell. The curvature greatly increases the frictional forces generated between the insulating material and the sheath, thus exposing movement of the insulating material within the sheath.
According to a second aspect of the present invention there is provided a device for measuring forces and pressures, comprising a load cell having in its interior a low shear force material. a piston movable so as to compress the low shear force material in use, and a resistive element distributed over the whole of the internal cross-sectional area of the load cell so that all of the resistive element is subjected to the force or pressure applied to the low shear force material by the piston, the resistive element having a specific resistance which is highly pressure sensitive and constituting a pressure sensitive resistance strain gauge.
It is surprising that the strain gauge which basically serves for pressure measurement and which follows the distortions of the objects under test. also produces excellent measurement results as a force transmitter within the framework of the present invention. The resistive element of the strain gauge is preferably made of manganin wire.
The arrangement of a strain gauge on an object to be tested normally calls for careful bonding so that the strain gauge follows any longitudinal changes in the object in use. In the present invention, only the securing of the strain gauge position is required, and this can be achieved by correspondingly simple bonding. The resistive element of the strain gauge can be insulated and can be provided between the low shear force material and a base of the load cell or the piston.
The strain gauge can be used in combination with a sheathed thermocouple element, in which case it has its ends connected to conductors of the latter. In this way, the whole of the metal resistive element providing measurement is subjected to the effects of the forces or pressures to be measured, and at the same time a space-saving and particularly reliable method of leading out of the load cell is ensured. Naturally, the resistive element of the strain gauge does not have to be in the form of a wire, but can instead be in the form of an etched resistance pattern in a known manner.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a sectional side view of a device according to the present invention and
Figure 2 is a plan view of the device shown in Figure 1 with a piston thereof removed.
The illustrated device for measuring forces and pressures comprises a load cell which includes a cylindrical body 1 having a central recess therein in which a vulcanised silicon rubber layer 2 is bedded. This layer can be stressed in use by a punch-like piston 3, considerable movement being allowed between the internal wall of the body 1 and the outer face of the piston 3. In order that the clearance may be maintained as large as possible, a seal ring 4 (which is otherwise unnecessary) is provided.
A strain gauge formed by a resistance wire 5 is arranged within the rubber layer 2, the undulations in the wire 5 being somewhat exaggerated in Figure 1 to facilitate visibility, the wire 5 normallv being arranged so as to run with a much flatter stroke. The ends of the resistance wire 5 are connected to a conductor formed by a sheath 6 of a sheathed thermocouple element and a conductor formed by a thermocouple wire 7, respectively. Both conductors are led sideways out of the body 1, a connection 8 being provided at the outer end of the sheath 6 and a further connection 9 being provided at the outer end of the thermocouple wire 7.
Figure 2 shows more particularly the manner in which the strain gauge (which is suitably controlled) is distributed over the internal cross-section of the load cell in meander-form.
WHAT WE CLAIM IS:
1. A device for measuring forces and pressures, comprising a load cell including a low shear force material. a piston movable so as to apply the force or pressure to be measured to the low shear force material, a resistive element whose specific resistance is pressure-dependent embedded in.the low shear force material so that all of the
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (12)
1. A device for measuring forces and pressures, comprising a load cell including a low shear force material. a piston movable so as to apply the force or pressure to be measured to the low shear force material, a resistive element whose specific resistance is pressure-dependent embedded in.the low shear force material so that all of the
resistive element is subjected to the force or pressure applied to the low shear force material by the piston, and a sheathed thermocouple element including a pair of conductors which are mutually insulated and connected to the ends of the resistive element respectively, the sheathed thermocouple element being led out of the load cell.
2. A device as claimed in Claim 1 wherein the low shear force material is flexible rubber.
3. A device as claimed in Claim 1 or 2.
wherein the thermocouple element extends out of the cell transversely to the direction of the effect of the force or pressure being measured.
4. A device as claimed in any preceding claim, wherein an outer jacket of the thermocouple element has an external diameter of between 0.15 and 3.0 mm.
5. A device as claimed in any preceding claim, wherein the thermocouple element is curved both inside the load cell and at its exit from the load cell.
6. A device for measuring forces and pressures, comprising a load cell having in its interior a low shear force material, a piston movable so as to compress the low shear force material in use, and a resistive element distributed over the whole of the internal cross-sectional area of the load cell so that all of the resistive element is subjected to the force or pressure applied to the low shear force material by the piston, the resistive element having a specific resistance which is highly pressure sensitive and constituting a pressure sensitive resistance strain gauge.
7. A device as claimed in Claim 6, wherein the low shear force material is flexible rubber.
8. A device as claimed in Claim 6 or 7, wherein the resistive element is made of manganin wire.
9. A device as claimed in Claim 6, 7 or 8, wherein the resistive element is insulated and is provided between the low shear force material and the base of the load cell or the piston.
10. A device as claimed in Claim 6. 7 or 8 wherein the resistive element is embedded in the low shear force material.
11. A device as claimed in any one of
Claims 6 to 10, wherein ends of the resistive element are connected to respective conductors of a sheathed thermocouple element.
12. A device for measuring forces and pressures, substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2710741A DE2710741C2 (en) | 1977-03-11 | 1977-03-11 | Device for measuring forces and pressures |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1599339A true GB1599339A (en) | 1981-09-30 |
Family
ID=6003417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9779/78A Expired GB1599339A (en) | 1977-03-11 | 1978-03-13 | Device for the measurment of forces or pressures |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE2710741C2 (en) |
| FR (1) | FR2383589A7 (en) |
| GB (1) | GB1599339A (en) |
| IT (1) | IT1094270B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106353183A (en) * | 2016-11-14 | 2017-01-25 | 安徽工程大学 | Internal force measuring and calibration device and calibration method thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4111149A1 (en) * | 1991-04-06 | 1992-10-08 | Bosch Gmbh Robert | PRESSURE SENSOR |
-
1977
- 1977-03-11 DE DE2710741A patent/DE2710741C2/en not_active Expired
-
1978
- 1978-03-10 IT IT7821077A patent/IT1094270B/en active
- 1978-03-10 FR FR7807060A patent/FR2383589A7/en not_active Expired
- 1978-03-13 GB GB9779/78A patent/GB1599339A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106353183A (en) * | 2016-11-14 | 2017-01-25 | 安徽工程大学 | Internal force measuring and calibration device and calibration method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2710741C2 (en) | 1986-11-13 |
| FR2383589A7 (en) | 1978-10-06 |
| IT7821077A0 (en) | 1978-03-10 |
| IT1094270B (en) | 1985-07-26 |
| DE2710741A1 (en) | 1978-09-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |