Weighing scales – Self-positioning – Electrical current generating or modifying
Patent
1991-09-19
1993-02-02
Miller, Jr., George H.
Weighing scales
Self-positioning
Electrical current generating or modifying
177DIG9, 428120, G01G 314, B32B 700
Patent
active
051831260
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to means for the transfer of forces to a beam in load measurement devices of the single bending beam type. In a single bending beam load measurement device, load and reaction forces are applied to a beam in equilibrium by means of force transmission means spaced from one another in the longitudinal direction of the beam. At a selected region of the beam the strain therein is measured, which arises from the bending of the beam by said forces, this strain being proportional to the distances between the location of the strain measurement region and the force transmission means and between the force transmission means themselves.
In such devices the beam is in use subjected to bending out of its rest plane, such that the alignment of the beam with the original line of application of the forces changes, as does the distance between fixed points on the beam. Such behaviour is to be contrasted with that of the beams which are employed in other devices such as, for example, shear beam load cells and parallelogram beam devices where distortion of the beam does not involve bending along the length thereof. Examples of parallelogram beam devices are described in Laimins U.S. Pat. No. 3,512,595 and Yamato Scale Company Australian Patent Specification No. 535,837.
Single bending beam devices are also subject to other modes of deformation as a result of imperfect loading conditions, and undergo, for example, twisting due to uneven load application and/or uneven support.
BACKGROUND ART
The problem of transferring forces to such single bending beam structure is addressed in Australian Patent Specification 44956/85, and in that specification elastomeric elements are used in two different ways to achieve force transfer to the beam. In one embodiment described in 44956/85, forces are applied to pins which are mounted in elastomeric sleeves within the beam, while in another embodiment, forces are applied to cylindrical elastomeric elements mounted above and below the beam.
SUMMARY OF THE INVENTION
The present invention seeks to provide arrangements which yield improved performance in such bending beam weighing devices, at lower cost. In particular, an object of the invention is to provide means for force transfer which will enable the bending beam to be of simple construction and of cheap material such as spring steel, which will require a minimum of preparation and machining of the beam itself and which will be tolerant of misalignment and the sort of abuse to which weighing devices are often subject in the field, without intolerable loss of performance.
This invention also relates to a weighing system which is particularly although not exclusively, suitable for use in the weighing of small animals, and a further object of the present invention is to provide a weighing system in which a load placed on a load receiving platform or otherwise over an extended area may be weighed with the use of a single strain gauge only, instead of requiring at least two strain gauges as in the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically in side elevation, a single bending beam weighing device;
FIG. 2 illustrates a load transfer element incorporating the present invention;
FIG. 3 illustrates the results of a creep test;
FIG. 4 illustrates the results of a dynamic test;
FIG. 5 shows in plan view a bending beam weighing device incorporating load transfer elements of the present invention;
FIG. 6 shows an end elevation of the device of FIG. 5;
FIG. 7 is a sectional elevation taken on the line 7--7 of FIG. 5;
FIG. 8 is a fragmentary sectional elevation taken on the line 8--8 of FIG. 5;
FIG. 9 shows a plan view of weighing apparatus according to an embodiment of a second aspect of the invention, with the load receiving platform removed;
FIG. 10 shows the weighing apparatus of FIG. 9 in side elevation;
FIG. 11 shows in plan view a further embodiment of the invention; and
FIG. 12 is a side elevation of the embodiment illustrated in FIG. 11.
A single bending beam weigh
REFERENCES:
patent: 3309922 (1967-03-01), Green
patent: 3661220 (1972-05-01), Harris
patent: 3938603 (1976-02-01), Shoberg et al.
patent: 4411326 (1983-10-01), Siegel
Abstract of Japan, M-149, p. 116, Jp, A, 56-155739 (Toukai Gomu Kogyo K.K.) Dec. 2, 1981 (02.12.81) "Manufacturer of Vibration-Proof Rubber With Plate Made of Epoxy Resin Planted With Bolt".
Abstract of Japan, M-92, p. 508, Jp, A, 61-70235 (Hino Motors, Ltd.) Apr. 11, 1986 (11.04.86), "Vibration Isolating Supporter of Engine".
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