DE2011867A1 - - Google Patents

Description

3083-70

PRECISION MECAIIQUE LABINAL
Dynamometric scales

The invention relates to the dynamometric scales with a pivotable balance arm, on which Λ two opposing forces, one of which thereof to a balance of the balance beam, in particular the horizontal position, may vary a corresponding average.

The invention relates to such scales especially, if not exclusively, those in which the changeable force partially bears the weight of one Push button 1 immersed in a liquid 2 (Pig * 1 and 2) is to which a device for measuring the level of this liquid 'belongs, as in particular in the am Filed July 30, 1965 and issued October 30, 1967 French Patent No. 1.504.410 and its first amendment, filed on June 14, 1966 and granted on March 25, 1968

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Patent No. 91.213 is described.

In such a device is the

Button 1 suspended from a cable 3, which loads a roller 4 carried by the balance beam 5 of a dynamometer 6, before it winds up on a drum 7, and an electrical voltage constantly formed by the dynamometer is used for Excitation of a motor 8 to drive the drum in the sense that in the event of a disturbance of the balance of the balance beam seeks to restore this.

The angular position of the drum is then

an image of the mirror height to be measured. It is determined by a counter 9, whose information is preferably immediate are expressed in level heights of the liquid.

To any connection between the electrical parts and the internal volume 10 of the liquid 2 containing Container 11 - which is essential if this liquid is a flammable product, e.g. a hydrocarbon - these parts are isolated by separating them from the volume by a tight wall 12 which through it magnetically on the one hand the transmission of the controls generated by the dynamometer 6 and on the other hand the coupling of the drum 7 with that by the motor 8 and the Order formed by payer 9 is made »

The invention aims in particular to make such dynamometers more sensitive and cheaper.

For this, according to a first feature

the invention of the balance beam of such a dynamometer is suspended from a thin metal lamella, which is bent into a V-shape along a horizontal edge, in particular at an angle of 90 °, the two free ends of this lamella, in particular by screws, on two fixed, higher or o contact surfaces lying deeper than this edge are attached, the attachment of the balance beam to this lamella in the immediate vicinity of this edge, preferably by clamping the bent part of the lamella between a V-shaped groove formed in a section of the balance beam and a cylindrical contact surface of another section of the balance beam, the radius of which is greater than the

009841/1171

is the inner radius of curvature of the bend of the lamella, this radius is preferably very small and on the order of a millimeter or a fraction of a Millimeters, the lamella preferably being covered by a thin foil made of a stainless alloy with a high elastic limit consists and preferably contains rectangular windows, which on each side of the bend of the lamella only one Let the framework exist.

In applications in which the angular positions of the balance beam are magnetically transmitted to an evaluation system, the dynamometer being preferred a mirror level indicator of the type mentioned above with mag- J netic transmission of its control commands through a dense * Heard through the wall, the following feature is also preferably used - which of course, if necessary, is also independent of the preceding can be used - used according to which the balance beam carries at least one permanent magnet, while a fixed holder carries a bridge made of resistors that are sensitive to the magnetic field generated by this magnet, whose fixed positions are determined so that the output voltage the bridge is zero when the balance beam is in equilibrium while it is positive or negative, when the balance beam is inclined in one sense or the other in relation to its position of equilibrium.

The invention is hereinafter referred to (f would take on the drawing explained by way of example.

Fig. 1 and 2, on which already above

reference was made to explain the state of the art, show very schematically a storage container for liquid hydrocarbon, which with a by the invention to improving mirror level indicator is equipped, or the main parts of the same.

Fig. 3 is a side view of a

inventive dynamometer for such a Spiegelst and display it.

Fig. 4 shows a detail of Fig. 3 on a larger scale.

Fig. 5 shows in a horizontal section,

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also on a larger scale, the suspension system of the balance beam this! dynamometer.

Pig. 6 is a perspective view of the lamella of this system.

Fig. 7 shows in a horizontal section

on an even larger scale than Fig. 3 that which the cable reel bearing end opposite end of the balance beam.

Figs. 8 and 9 show in a perpendicular

Section along the line VIII-VIII of FIG. 9 or in plan view of a housing firmly connected to the sealed wall, on which this end of the balance beam passes.

Fig. 10 shows the circuit of a resistor bridge accommodated in this housing.

Fig. 11 is a diagram of the changes

the output voltage of this bridge as a function of the inclination of the balance beam.

In the preferred embodiment shown, the balance beam 5 of the dynamometer is V-shaped around a horizontal edge 14 bent metal lamella attached.

The apex angle of this V is preferably of the order of magnitude of 90 °, and the inner radius of curvature of the bend is as small as is compatible with the material used. If the lamella, as is preferably the case, is formed by a thin foil with a thickness of 0.2 mm made of a stainless alloy, which is sold by the Soci ^ te Metallurgique d ¹ IMPHY under the name PHYNOX (with 40 < For cobalt, 20 % chromium, 16% nickel, 71 ° molybdenum and 17 ° iron), this radius is expediently no more than 1 mm.

The two ends of the lamella 13 are through.

Screwing in screws 15 attached to two flat contact surfaces belonging to a fixed holder 16 and having a corresponding inclination.

This holder 16 has the shape of a here

cylindrical bushing, the middle portion of which is reinforced by a thickening with a press fit in one of the wall 12 belonging Collar 17 is pressed in.

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That lying on the side of the volume 10 The end of this socket is open, while its other end is closed by a sealed base 18.

The ends of the lamella 13 are attached to the beveled edges of the open end.

The attachment of the balance beam 5 to this

lamella can be made in any desired manner, in particular by welding, but preferably a mechanical one Restraint used. · "

The balance beam preferably has for this purpose

two independent sections (Ej ₁ , 5 ₂ »Fig. 4 and 5), which in particular each have one of the two. Form arms of the balance beam, these sections being united with one another by screwing in screws 19, the bent zone of the lamella being clamped between them.

This zone is preferably between a

V-shaped groove cut out in one of the two sections 20 and a roller 21 clamped, the radius of which is greater than is the inner radius of curvature of the kink of the lamella, where the depth of the hat is e.g. the order of magnitude of the radius of the Has roller.

If r_ is the radius of the roller 21 and R

the distance between one of the clamped on the socket 16 The feet of the lamella 13 and its geometric center C (point of intersection of the two halves of the lamella), the ratio r / R must be as small as possible in order to maximize the rigidity of the lamella largely, this ratio being suitably less than 1/10 for the above example.

Step in the execution shown

the screws 19 not through the lamella. One of the two sections 5 ₂ »nat the shape of the blade cross-strap, and each screw 19 secured to one arm of this bracket to the other section 5 ^.

To improve vertical flexibility the lamella 13 without impairing the definition of the position of the balance beam produced by it is two-dimensional in each a rectangular window 23 (Fig. 6) cut out of their surfaces, so that then the lamella from two along the edge 14

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superimposed framework.

The suspension of the balance beam obtained in this way has numerous advantages over the previous ones known designs, in particular a greater sensitivity due to their lower rigidity, as well as a more economical, simpler and stronger structure.

In order to further improve the properties of this dynamometer, it is expedient according to the invention deriving the desired electrical control from the Vibrations of the balance beam by means of a permanent magnet attached to the balance beam and a bridge made of resistors, which are sensitive to the magnetic field generated by this magnet and are housed in a solid, sealed housing

In the embodiment shown, the

carried by the end of the balance beam 5 adjacent to the bottom 18 Magnet split into two U-shaped magnets 24, which are united with one another by two pole shoes 25 so that that in the air gap between these shoes A strong magnetic field H (e.g. of the order of 5,000 Gauss) is generated.

In this air gap there is a

Versehmälerter portion of a sealed housing 26, which has a printed circuit 27 with four magnetically influenceable Contains resistors 28 (Fig. 7 »8 and 10), which are combined to form a bridge so that the opposite Parts change in the same direction.

These magnetically influenceable resistances are semiconductors, the resistance of which is in puncture the strength of the magnetic field acting on it changes. Such Semiconductors are, for example, those sold by SIEMENS under the designation PP 28-D470.

The position of the circuit 27 is adjustable, in such a way that it can be pushed more or less into the housing 26 so that the magnetically influenceable Resistors 28 take up an exact position with respect to PeId H, when the balance beam is in the balance.

After the adjustment, aie is screwed through a Sohraube 29 set, and the arrangement is

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made indismountable in that the housing 26 with a electrically insulating but good heat conducting material is filled, e.g. the silicone elastomer sold by Societe * SISS under the name S> ILASTEN RTV 860, whose Thermal conductivity can be improved by adding a suitable substance, e.g. beryllium oxide. Such a one Filling reduces the temperature sensitivity of the resistors. Furthermore, their thermal drift is due to the automatic Compensation greatly reduced by holding the feet.

The housing 26 is on a shoulder 30

(Fig. 3 and 8) of the socket 16 with the help of screws 31 (Fig. 9) attached.

Fig. 11 shows a curve 32 which the

Changes in the output voltage Us of the resistance bridge 28 (for a supply voltage Ua of the bridge) as a function of the angle θ represents the imbalance of the balance beam, where the voltages are expressed in volts and the angles in degrees.

The vibrations of the balance beam 5 experience a significant viscous damping, as the corresponding Movements of the magnetic field H generated by the magnets 24-25 carried by the balance beam, electric currents in the housing 26 induce, which for this purpose consists of a non-magnetic, electrically conductive material »(e.g. an aluminum alloy) and forms a short circuit. These currents in turn generate on the balance beam moments which oppose the movements * which they have produced.

The value of this damping becomes useful

adjusted so that these movements are made practically aperiodic, but without the normal operation of the device disturb.

By means of such an arrangement

Control achieved with magnetically influenceable resistors offers numerous advantages over the previously known arrangements, in particular a greater sensitivity, a lower cost price and better damping of the Vibrations of the balance beam.

Fig. 3 shows two stops 33 of the balance beam 5 to limit the vertical deflections of the

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same by their contact with the opposite sides of the socket 6 and one also carried by the balance beam Counterweight 34 for setting the equilibrium position of the same.

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Claims (10)

■ - 9 - 3083-70 Claims / 1 *) Dynamometric balance with a pivotable balance beam, on which two opposing forces act, one of which is on either side of the balance of the balance beam, in particular the horizontal position of the. same, corresponding mean value, characterized in that the balance beam (5) is suspended from a thin V-shaped metal lamella (13) bent over along a horizontal edge (14), the two free ends of which are at two above and below fixed contact surfaces arranged on this edge (14), the balance beam (5) being fastened to this lamella (13) in the immediate vicinity of this edge (14). -m 2.) Dynamometric balance according to claim 1,> characterized in that the attachment of the balance beam (5) to the lamella (13) by tensioning the bent section of the lamella between a V-shaped groove formed in a section (5a) of the balance beam (20)) and a cylindrical contact surface (21) of another section (5 ″) of the balance beam, the radius of curvature (r) of this latter contact surface being slightly larger than the smallest possible inner radius of curvature of the bend of the lamella. ' 3) Dynamometric balance according to claim 2, characterized in that the balance beam. (5) from two together screwed sections (5-, 5g) consists of which one (5 ″) has a bracket that extends over the lamella (13). j 4.) Dynamometrisohe balance according to claim 3, characterized in that the cylindrical contact surface belongs to a roller (21) clamped _{between the two balance beam sections (5 «t 5«).} 5 ») Dynaraometric scales according to one of the Claims 1 to 4, characterized in that in each of the Both surfaces of the lamella (13) a rectangular window (23) is cut out, around which there is only a frame remain. 6 p.) Dynamometric scales with a swiveling balance beam on which two opposing forces act, one of which is about one of the balance 00986 1/117 1 - 10 - 3083-70 bar may fluctuate according to the mean value one of claims 1 to 5, as well as with means for magnetic transmission of the angular positions of the balance beam to an evaluation system, characterized in that the balance beam (5) carries at least one permanent magnet (24), and that a the fixed holder (16) carries a bridge made of resistors (28) which are sensitive to the magnetic field generated by the magnet (24), the fixed positions of these resistors (28) being determined so that the output voltage of the bridge is zero when the balance beam is in equilibrium while it is positive or negative, depending on whether the balance beam is in the one or the other sense in relation to its equilibrium position is inclined. 7 ·) Dynamometric balance according to claim 6, characterized in that the resistors (28) which are sensitive to the magnetic field are located in a small air gap of the Magnets (24) arranged narrowed part of a housing (26) are housed. 8 ·) Dynamometric balance according to claim 6 or 7, characterized in that the resistors (28) sensitive to the magnetic field are connected in such a way that the in of the bridge opposing resistances change in the same direction in puncture of the magnetic field, with all resistances are embedded in an electrically insulating but highly thermally conductive mass, which the housing containing them (26) fill in 9 ·) Dynamometric balance according to claim 7 or 8, characterized in that the condensed part of the housing (26) made of a non-magnetic, highly electrically conductive Material. 10.) Dynamometric balance after a of claims 1 to 9, characterized in that they a known device for measuring the mirror height of a Fluid belongs to which one is partially in the fluid (2) immersed button (1), which on a cable (3) is suspended which, before being wound onto a drum (7), is a roll carried by the balance beam of the balance (4) loaded, whereby an electrical 009841/1171 - 11 - , 3083-70 tric voltage is used to excite a motor, which drives the drum in the sense that in the event of a fault in the This seeks to restore the balance of the balance beam. 009841/117 1