FR3054033A1 - BALANCE INCLUDING OVERLOAD PROTECTION - Google Patents

Abstract

The invention relates to a balance comprising an apron for receiving (2) a load supported on a false apron (3) for receiving force supported by a base (4). The apron (2) is supported on the false apron (3) via systems (14) of energy absorption and limitation of an overload, mounted on the false apron (3) and comprising each a mechanism (15) of energy absorption interposed in abutment between the deck (2) and the false apron (3), being movable between a rest position and an overload position, each absorption mechanism d energy (15) being provided with a stop (19) coming into contact with the base (4) only when this mechanism reaches its overload position.

Description

Holder (s): PRECIA Société anonyme.

Extension request (s)

Agent (s): CABINET BEAU DE LOMENIE Civil society.

1241 SCALE WITH INTEGRATED OVERLOAD PROTECTION.

FR 3 054 033 - A1 \ 57) The invention relates to a balance comprising an apron for receiving (2) a load resting on a false plate (3) for receiving force supported by a base (4). The apron (2) is supported on the false apron (3) by means of systems (14) of energy absorption and of limitation of an overload, mounted on the false apron (3) and comprising each an energy absorption mechanism (15) interposed in support between the deck (2) and the false deck (3), being movable between a rest position and an overload position, each absorption mechanism d energy (15) being equipped with a stop (19) coming into contact with the base (4) only when this mechanism reaches its overload position.

The present invention relates to the technical field of measuring devices or scales for determining the mass of a body using the action of gravity on this body.

The invention relates more precisely to medium-range and fine-precision scales such as, for example, scales which can, at the metrological level, be certified up to 30 kg with an accuracy per gram in class II or up to 150 kg in class III.

The object of the invention finds a particularly advantageous application for a balance placed and used on the floor.

Conventionally, a balance comprises an apron for receiving a load resting on a false apron for receiving force supported by a base. The balance includes a system for weighing the load deposited on the apron. This weighing system comprises at least a force sensor, a measurement chain, digital processing of the measurement signal and a man-machine interface.

In the preferred application of the invention, the force sensor is a strain gauge sensor using the principle of extensometry. Extensometry is the technique that transforms mechanical deformation into a measurable electrical signal through a strain gauge sensor. The strain gauges consist of a fi! very thin bonded to an insulating support whose resistance is almost invariable depending on the temperature.

Of course, the balance according to the invention can be equipped with a force sensor implementing different technologies. For example, this force sensor can for example use optical fiber or a vibrating cord. The principle is to obtain an electrical signal representative of the mechanical deformation generated by the application of a force.

This sensor must be protected from shocks when depositing the masses on the bulkhead to avoid breakage or permanent deformation of the sensor, permanently immobilizing the sensor. The scales are thus equipped with stops which block the false apron when the weight of the load exceeds the weighing capacity of the scale or when the load is suddenly released from a certain height. In general, these stops are adjusted in the factory for each of the scales, by a screwing operation by depositing a standard weight at different places on the scale.

The difficulty lies in the adjustment of this stop, linked to the tolerances of the pitch of the screw used, the flatness and the deformation of the false apron and the deformation of the sensor of the order of a maximum of mm. An incorrect adjustment results in either the inability to weigh up to the maximum range or the ineffectiveness of the protection. In the first case, the balance is non-compliant while in the second case, the sensitivity to the destruction of this balance increases. The adjustment during the manufacture of this stop is important but in practice constitutes a delicate operation to carry out.

The object of the invention is to remedy the drawbacks of the prior art by proposing a balance protected from shocks and overloads when depositing the masses on the apron, using a protection protection mechanism. simple work, not requiring a delicate operation of adjustment.

To achieve such objectives, the scale according to the invention comprises an apron for receiving a load supported by a false apron for receiving force supported by a base, the scale comprising a system for weighing the load deposited on apron.

According to the invention, the apron is supported on the false reception apron by means of energy absorption and overload limitation systems, mounted on the false apron and each comprising a mechanism for energy absorption interposed in support between the deck and the false deck, being movable between a rest position and an overload position corresponding to load values on the deck, respectively zero and maximum, each absorption mechanism d energy being equipped with a stop coming into contact with the base only when this mechanism reaches its overload position.

In addition, the balance according to the invention may also comprise in combination at least one and / or the other of the following additional characteristics:

each energy absorption mechanism includes a spring dimensioned to absorb energy as long as the overload value is not exceeded;

- the energy absorption spring is a compression spring with turns or a wave spring;

each energy absorption mechanism has a rod which is constantly stressed at its first end by the apron, this rod freely passing through the false apron while being equipped at its second end by the stop coming into contact with the base only when this mechanism reaches its overload position;

- Each rod is constantly stressed at its first end by the deck, being fixed to the latter by an assembly;

- Each rod is constantly stressed at its first end by the apron, being fixed to the latter by a thread type assembly cooperating with a threaded housing;

- Each rod is constantly stressed at its first end by the apron, while being supported on the underside of the load receiving apron;

- Each rod is supported on the underside of the deck, using a support pad to which the first end of the rod is fixed by a thread type assembly cooperating with a threaded housing;

- Each energy absorption mechanism includes a spring through which the rod provided with the stop;

- a damping block is interposed between the false deck and the stop;

- at least three energy absorption and overload limitation systems, arranged on the false deck;

- the weighing system includes a force sensor which is bypassed when an overload occurs.

Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

Figure 1 is a perspective view showing an embodiment of a balance according to the invention.

Figure 2 is a perspective view showing the scale according to the invention illustrated in FIG. 1 without the apron.

Figure 3 is a sectional elevation view of part of a balance, showing an energy absorption system and limitation of an overload according to the invention.

Figure 4 is an elevational sectional view of part of a balance, showing an energy absorption system and limiting an overload according to the invention, in the overload position.

Figure 5 is an exploded perspective view showing an embodiment of an energy absorption system and limitation of an overload according to the invention.

As can be seen from the Figures, the object of the invention relates to a balance 1 comprising an upper plate 2 for receiving a load, also called an apron. Conventionally, this deck 2 has the shape of a parallelogram and is based on a false plate 3 for receiving force, also called false deck. This false apron 3 which is for example made by an X-shaped plate, is supported by a base 4 made in any suitable manner. In the example illustrated, this base 4 is produced by an X-shaped plate fitted with support legs 5. Of course, the false apron 3 and the base 4 may have shapes different from those illustrated by way of example only.

The balance 1 comprises a system 7 for weighing the load deposited on the deck 2. The weighing system 7 is not described in detail because it is well known to those skilled in the art and is not precisely part of the subject of the invention. This weighing system 7 comprises at least one force sensor 9, a measurement chain not shown, digital processing of the measurement signal and a man-machine interface 11 such as a control and display screen.

In a preferred application of the invention, the force sensor 9 is a strain gauge sensor using the principle of extensometry. The force sensor 9 comprises strain gauges mounted on a bar 12 fixed between the false apron 3 and the base 4. Of course, the scale according to the invention can be equipped with a force sensor implementing different technologies, for example using optical fiber or vibrating wire.

According to the invention, the deck 2 rests on the false deck 3 by means of energy absorption and overload limitation systems 14. These systems 14 are mounted on the false deck 3 The balance 1 comprises at least three and in the example illustrated in the drawings, four systems 14 for absorbing energy and limiting an overload, arranged on the false apron 3 at each of its corners.

Each system 14 includes an energy absorption mechanism 15 interposed in support between the deck 2 and the false deck 3, being movable between a rest position corresponding to a zero value of the load on the deck 2 (Fig. 3) and an overload position corresponding to a maximum value of the load on the deck 2 (Fig. 4).

Each energy absorption mechanism 15 is dimensioned to absorb energy as long as the overload value is not exceeded. In the example illustrated, each energy absorption mechanism 15 includes a spring 16 dimensioned to absorb energy as long as the overload value is not exceeded. For example, the energy absorption spring 16 is a coil compression spring or a wave spring. Of course, each energy absorption mechanism 15 can be made differently. Thus, each energy absorption mechanism 15 includes any other component comparable to a spring, for example a rubber pad, dimensioned to absorb energy as long as the value of the overload is not exceeded.

Each spring 16 which is interposed between the deck 2 and the false deck 3 is subject to the load of the deck 2 so that it has an initial length corresponding to its rest position and a compressed length less than its initial length and corresponding to its overload position. Each spring 16 and consequently the apron 2 is able to occupy any position between its two extreme positions.

Each energy absorption mechanism 15 comprises a rod 17 constantly urged at its first end 17a by the deck 2. This rod 17 freely crosses the false deck 3 through a through hole 18 while being equipped at its second end 17b by a stop 19 coming into contact with the base 4 only when this mechanism 15 reaches its overload position. According to a preferred embodiment, each rod 17 passes through a spring, that is to say extends inside the turns of the spring. Between the rest and overload positions, the rod 17 moves following the movements of the deck 2 and being guided in translation by any suitable means.

Each rod 17 is constantly stressed at its first end 17a by the apron 2, being either supported on the underside of the apron 2 or fixed to this apron 2. In the example illustrated in the drawings, each rod 17 is supported on the underside of the deck 2, using a support pad 21. Each pad 21 is in the form of a cap having a flat bearing face 21a with the underside of the deck 2. By example, the pads 21 are made of plastic.

Each rod 17 is fixed to the support pad 21 in any suitable manner. In the preferred example illustrated in the drawings, each rod 17 is fixed to the support pad 21 by a thread type assembly. The first end 17a of each rod 17 is threaded and cooperates with a threaded housing 23 presented by the support pad 21. Preferably, this threaded housing 23 is produced by a threaded socket 24 attached which is fixed inside d 'a well 25 presented by the support pad 21.

In practice, each rod 17 is a screw whose head forms the stop 19. The assembly and adjustment of each energy absorption mechanism 15 is relatively simple since it is sufficient, after having threaded the spring 16 on the rod, screw this rod fully into the threaded socket 24 to obtain the correct adjustment.

In the embodiment described above, the deck 2 is independent from the rods 17.1! it should be noted that the rods 17 can be provided for being fixed to the deck 2 by an assembly of all types known per se. For example, each rod 17 can be fixed to the deck 2 by a thread type assembly cooperating with a threaded housing arranged from the underside of the deck 2.

Each rod 17 has at its second end 17b, the stop 19 which is positioned between the false apron 3 and the base 4. In the absence of a load on the apron 2, the stop 19 is free from any movement . The stop 19 can be supported or not on the underside of the false apron 3. According to an advantageous embodiment, a damping block 26 is interposed between the false apron 4 and the stop 19, Thus, in the position of rest, the stop 19 is supported on the false apron 3 by means of this damping block 26. For example, this damping block 26 is mounted freely around the rod 17 while being retained at its lower part by the stop 19.

It should be noted that this damping block 26 also ensures the translational guidance of the rod 17. Of course, it can be envisaged to eliminate the use of a te! damping block 26. According to this alternative embodiment, the rod 17 which simply passes through the false apron 3 can be guided in translation by a sleeve of suitable length.

In the overload position, the stop 19 comes into contact with the base 4. Preferably, the base 4 is provided with support pads 4a on each of which a stop 19 comes into contact in the event of an overload.

It follows from the above description that the balance according to the invention is effectively protected against a load exceeding the weighing capacity of the balance or when the load is suddenly dropped from a certain height. In fact, in the event of an overload on the bulkhead 2, the stop 19 comes to bear on the base 4 so that the force sensor 9 does not perceive this overload taking into account the derivation of this overload towards the base 4. The force sensor 9 is thus bypassed when an overload occurs.

The energy absorption mechanisms 15 make it possible to absorb the energy as long as the overload value is not exceeded. These mechanisms ensure the damping of the movements of the deck 2. It should be noted that the damping blocks 26 make it possible to damp the return movement of the rods 17, that is to say the movements of relative spacing of the deck 2 by report to the false deck 3.

The invention is not limited to the examples described and shown since various modifications can be made without departing from its scope.

Claims (11)

1 - Balance comprising an apron for receiving (2) a load resting on a false apron (3) for receiving force supported by a base (4), the balance comprising a system (7) for weighing the load deposited on the bulkhead, characterized in that the bulkhead (2) rests on the false bulkhead (3) for receiving by means of energy absorption and overload limitation systems (14) , mounted on the false apron (3) and each comprising a mechanism (15) of energy absorption interposed in support between the apron (2) and the false apron (3), being mobilized between a rest position and a overload position corresponding to load values on the bulkhead, respectively zero and maximum, each energy absorption mechanism (15) being equipped with a stop (19) coming into contact with the base (4) only when this mechanism reaches its overload position. 2 - Balance according to claim 1, characterized in that each energy absorption mechanism (15) comprises a spring (16) dimensioned to absorb energy as long as the overload value is not exceeded. 3 - Balance according to claim 2, characterized in that the energy absorption spring (16) is a compression spring with turns or a wave spring. 4 - Balance according to one of claims 1 to 3, characterized in that each energy absorption mechanism (15) comprises a rod (17) urged constantly at its first end by the apron (2), this rod ( 17) freely passing through the false apron (3) being equipped at its second end by the stop (19) coming into contact with the base (4) only when this mechanism reaches its overload position. 5 - Balance according to claim 4, characterized in that each rod (17) is constantly stressed at its first end by the apron (2), being fixed to the latter by an assembly. 6 - Balance according to claim 5, characterized in that each rod (17) is constantly stressed at its first end by the apron, being fixed to the latter by a thread type assembly cooperating with a threaded housing. 7 - Balance according to claim 4 characterized in that each rod (17) is stressed constantly at its first end by the apron (2), 5 being supported on its underside of the load receiving deck. 8 - Balance according to claim 7 characterized in that each rod (17) is supported on the underside of the deck, using a support pad (21) to which the first end of the rod (17) is fixed by a thread type assembly cooperating with a threaded housing (23). 10 9 - Balance according to one of claims 4 to 8, characterized in that each energy absorption mechanism (15) comprises a spring (16) traversed by the rod (17) provided with the stop (19). 10 - Balance according to one of claims 1 to 9, characterized in that a damping block (26) is interposed between the false apron (3) and the 15 stop (19). 11 - Balance according to one of claims 1 to 10, characterized in that it comprises at least three systems (14) of energy absorption and limitation of an overload, arranged on the false apron (3) . 12 - Balance according to one of claims 1 to 11, characterized in that the weighing system (7) comprises a force sensor (9) which is shunted when the appearance of an overload. 1/3