DE3336069A1 - FORCE MEASURING LOAD CELL FOR ELECTRONIC SCALES AND THE LIKE - Google Patents

Description

T ¹ Ο · » If * · · f * · * -" * - '* Patent Attorneys and Ji

IEDTKE - DUHLING "l \ ll * NE" IaRUPE · „·. · Representative at the EPO fi

Φ »***> <> * ** paa a <s

ή / "* *. ** O.:. * .. * ■"»->"%." Dipl.-Ing. H. Tiedtke ι

ΊΡΈΙΛ-ΜΑΝΝ - CIRAMS - OTRUIF Dipl.-Chem. G. Bühling

Dipl.-Ing. R. Kinne Dipl.-Ing R Grupe

-3 Dipl.-Ing. B. Pellmann

* - Dipl.-Ing. K. Grams

Dipl.-Chem. Dr. B. Struif

Bavariaring 4, Postfach 8000 Munich 2

Tel .: 089-539653 Telex: 5-24 845 tipnt Telecopier: 0 89-537377 cable: Germaniapatent M

October 4th 19Π

DE 3340
case 1615 CG

Kaj. EH Blomster
Helsinki / Finland

Force measuring load cell for electronic scales and the like.

The invention relates to a force-measuring load cell for electronic scales and the like that are based on the measurement the expansion and compression in the surface layer of a loaded MeGkörper based, as determined by the Application of resistance strain measurement is known at the resistance of the extensometer by means of a resistance meter will measure.

Dresdner Bank (Munich) loo. 3939844 G / 4

Bayer. Vercinsbnnk tMurichcn) loo ϋΠΠ! Ϊ4Ι

Postal check (MiI (IChCIi) Kto R? 0 - i-3-804

- 4 - DE 5-54Ü

There are a large number of measured bodies or load cells of various shapes that can be used as this type of force-measuring Load cells are known. But besides that they are too much are expensive, they have certain disadvantages. E.g. with longitudinal loading of cylindrical measuring bodies, the surface tension is formed in different directions, so it is necessary that the resistance strain gauge in different directions are arranged, their arrangement

ig is not always possible. There are also diagonally loaded ones square strain gauges as described in US Pat 2,986,931 (73-141). In addition to being relatively expensive, the latter has its disadvantage square shape which, in addition to bending, is also subject to tensile and compressive stress. The inventive The measuring body differs from it, among other things, in the thin sides, i.e. the measuring sides of the oblique parallelogram form a 90 ° angle with the diagonal measuring direction and are almost only subject to pure bending.

The object of the invention is to provide a particularly cheap and precise, i.e. a competitive load cell create. A Cheaper Way of Manufacture i-. '’Is achieved by the cells or measuring body by cutting off pieces adapted to the desired measuring range from a drawn one profiled metal rod manufactured, whereby the different measuring ranges no extra profile drawing tool require. Characteristic feature of the invention is it that it includes a force-measuring load cell that consists of consists of a diagonally loaded, leaning parallel-shaped body, which at its two opposite Sides is thick and relatively inelastic, while on the other sides, the so-called measuring sides, to which the measuring strips are attached, is thin and forms a 90 ° angle with the load line. Of the

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Measuring body can be designed if necessary ho that two trained Surfaces serve as overload protection, in which the surfaces, when they touch »I, the deformation

restrict.
5

The invention is described below with reference to schematic drawings of various exemplary embodiments, the reference symbols relating to the accompanying drawings.
10

Rig. 1 shows schematically the deformation of an inventive Cell in the unloaded, in the loaded with compressive stress and in the tensile

, c ■ ■ voltage loaded condition.

Fig. 2 shows an axonometric example of application of the cell.

3, 4 and 5 show three different application examples of the cell.

Figures 6, 7 and 8 show the upper part of a cell in which none, one and two constrictions are arranged on the thin side.

Figures 9, 10 and 11 show the upper part of a cell with the thin sides at different angles with the egg load line.

Figures 12, 13 and 14 show different arrangements

for overload protection.

The load cell according to the invention can be used both under pressure as well as with tensile load. Fig. 1 shows very exaggerated how the unloaded load cell on the left by pressure

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and tensile load is deformed. For overload protection at Pressure load is the center of the load cell with parallel, flat surfaces perpendicular to the direction of the load p- 1 formed, which mutually in the event of overload touch to prevent thin sides 2 from bending or breaking. The overload limit can and must of course be set so that no permanent deformation occurs in the thin sides 2. For the Zugiq load, this single overload protection cannot be used and the overload must be caused by other devices be prevented.

The inventive construction of a weighing body or The cell is further shown in FIG. Except for the already mentioned central surfaces 1 and the thin sides 2 of the inclined parallelogram, there are still thick, practically non-deformable sides 3 of the parallelogram. Between A spacer 4 can be used as overload protection for surfaces 1 will. At both ends of the load cell (i.e. top and bottom) there are surfaces 5 perpendicular to the direction of the load and thereby formed parallel to the surfaces 1 having in the center threaded mounting holes which are arranged in the direction of the load line are. As already mentioned, the cells consist of rectangular cut pieces of a drawn profiled Metal rod of suitable thickness, which depends on the desired measuring range. The thickness of the cell can also be increased by cutting it off can be changed along dashed lines 7 according to FIG. Resistance strain gauges 8 can be inexpensive at the locations shown in Figure 2; but they can also be anywhere on the thin side or attached to both sides.

Figure 3 shows schematically a cell with in central areas 1 without spacer 4. Figure 4 shows a cell without

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the central area 1, which is not used for pressure loading can be. Figure 5 shows a cell in which the thick sides of the oblique parallelogram are curved and the

is designed with the surfaces 1 for a spacer 4. 5

Figure 6 shows the upper part of a cell, the thin side of which has no constrictions. In Figure 7, the thin side has one and in Figure 8 it has two constrictions. These constrictions are mostly used when the load is less, when _ a greater sensitivity of the weighing body is required. Figure 9 shows a cell in which the thin sides at 90 ° Stand at an angle to the load line. In Figure 10, the corresponding angle 120 ° and in Figure 11 60 °. However, the last two cases should be avoided because the

, c inaccuracy of the cell, the greater the greater the Deviation of 90 °. Figure 12 shows how the spacer 4 of the overload protection maybe preferably in a cell according to Figure 3 can be arranged. It can be glued to the lower end and replaced if necessary will. In the case according to FIG. 13, no spacer 4 is required, since the middle surfaces 1 of the cell already do are so close together that they are already used as overload protection function. FIG. 14 shows how the spacer 4 can be arranged in a cell according to FIG.

When the cell is loaded, exactly the same deformations occur in both thin sides 2. While the Both ends of the thin sides 2 with the thick sides firmly: are connected (see Figure 1), the thin sides 2 of the cell bent under load in S-shape, as shown in Figure 1, where the deformations can easily be measured. Figures 1, 2, 6, 7 and 8 give examples of the ν arrangement the resistance strain gauge 8 on.

Compared to the previous solution, the invention offers

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the following advantages:

- The oblique parallelogram shape with the thin sides

2 are arranged at right angles to the load line, b

provides very precise values.

- In the case of the cell designed according to the invention, it is easy to to arrange an overload protection.

- The manufacture of the cell is through into fitting pieces

Cutting a qezoqenen profiled metal rod particularly economical.

A force-measuring load cell for electronic scales and the like is based on the measurement of elongation and the Compression in the surface layer of a loaded measuring body in a way that is caused by the application of resistance strain measurement is known, in which the resistance of the strain gauge (8) by means of a resistance bridge is measured. Included in the embodiment according to the invention

the measuring body has a diagonally loaded, essentially oblique 20

parallelogram-shaped body with two opposite, thick and relatively stiff places (3), whereas the other side so-called MeGssiten (2) thin and vertical or are almost perpendicular to the load line. In addition, the

Measuring body be designed if necessary so that it has an over-25

load protection (1) or be equipped with one (4) can.

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Claims (1)

Τ · r * .. Ι / ' ... f \ · ♦ " Patent attorneys and * ■ * IEDTKE * DUHLING-lYfNNjE. - VSRJJRE; ..; .; Representative at the EPO ψ r \ / * \. ^: "" ^\: * .L \ ^'\, Dipl.-Ing H.Tiedtke I HELLMANN - Uram... "OTRUIF Dipl.-Chem. G. Bühling Dipl.-Ing. R. Kinne Dipl.-Ing. R Group Dipl.-Ing. B. Pellmann Dipl.-Ing. K. Grams 3-3-3 6 UP9 Dipl.-Chem. Dr. B. Struif Bavariaring 4, Postfach 2C 8000 Munich 2 Tel .: 89-5396 Telex: 5-24 845 tipat Telecopier: 0 89-537377 cable: Germaniapatent MC October 4th 1983 DE 3340 case 1615 CG Claims [Ij Force- measuring load cell for electronic scales and the like, which are based on the measurement of elongation and compression in the surface layer of a loaded measuring body in a manner known from the application of resistance strain measuring technology, in which the resistance of the extensometer is measured by means of a resistance bridge is characterized by a diagonally loaded, essentially oblique parallelogram-shaped body, the ztr; egg opposite sides, thick and relatively stiff, whereas the other sides, so-called measuring sides (2), on which the measuring strips (8) are arranged, are thin and form a right angle with the load line, and if necessary the measuring body can be designed so that two of its surfaces (1) serve as overload protection, din in cm η they touch each other, restrict the deformation. 2, weighing cell according to claim 1, characterized in that the direction of the measuring sides (2) deviates somewhat from the 90 ° position in relation to the load line,; ibr »r Dresdner Bank (Munich) Account 3939844 Bayct Vqroinsbank (Munich! Klo SOB941 Piretsctwk iMuiichi-n) Account 6 * 0 4: i ni). ^1st - 2 - DE 3340 no more than 30 ° in either direction. 3. Weighing cell according to claim 1, characterized in that that the thick sides (3) of the oblique parallelogram are curved. 4. Load cell according to claim 1, characterized in that the measuring sides (2) with one or two constrictions - ^ q genes are formed. 3. Load cell according to claim 1, characterized in that the measuring body is formed in the middle with two flat surfaces (1) which are at right angles to the load line, which are pressed against each other when overloaded in order to act as overload protection serve, or between which separate spacers (4) can be arranged. 6. A method for producing a load cell according to one of the preceding claims, characterized in that the measuring body is designed so that it can be made from a drawn, profiled metal rod simply by cutting off pieces that match the desired measuring range.
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