FR2840065A1 - Equipment for measuring grain in a silo, comprises rigid rod which supports an outer flexible tube to enclose incompressible liquid which is also in contact with an electrical pressure sensor - Google Patents

Abstract

Two rigid rod elements (2,3) are connected together to form an inner chamber (10) which contains an electrical pressure sensitive sensor (5). One rod element partly supports a flexible tube (4) which contains within it's envelope (11) an incompressible liquid. The liquid is exposed to outer grain pressure through the unsupported portion (40) of the tube and the liquid is also in contact with the sensor through a drilling (21)

Description

[Activation.

  DEVICE FOR MEASURING THE FILLING STATE OF A SILO

  The present invention relates to the measurement of the filling level of chambers used for the storage of, grain or powder products. Wile was especially designed for the

  remote management of stocks of agro-products

  food such as cattle feed.

  It should be recalled that in the agricultural field, each holding generally has a silo screen of varying sizes which is filled on demand by a supplier of products seen in powder or granules. And in practice, it is not uncommon for a breeder to realize at the last moment that he is out of stock of an essential product and then requests to be delivered urgently, which induces additional costs.

important logistics.

  The invention proceeds from a reflection in order to solve this problem, starting from the basic idea of establishing a remote control, preferably at the supplier itself, of the filling state of

  ['all the silos of his clientele.

  At the present time, there are many devices for measuring the filling level of silos, such as radar systems, ultrasonic systems, mechanical systems with load cells or strain gauges placed at the base, etc. But all have the disadvantage of being expensive in themselves and / or by their implementation. However, cost is an important parameter in this application, due in particular to the multiplicity of devices to be installed in the same operation. On the other hand, there will be no need for these devices to be of great precision provided that their reliability is assured. An object of the invention has therefore been to provide a device for measuring the filling level of an enclosure for grain or powder products which is of simple and gable design, of low cost, and

easy and quick installation.

  Another object of the invention has been to provide such a measuring device requiring, in order to operate, only an extremely low electric current, for security purposes. According to the invention, such a device for measuring the filling level of a storage enclosure for grain or powder products is characterized in that it comprises a substantially non-expandable envelope filled with an incompressible liquid, which envelope has a window closed by a flexible wall and is intended to be placed in the lower part of said enclosure with said window facing upwards, facing the gravity vector; as well as a pressure sensor intended to transform into electrical signals the pressure differences generated in the liquid inside said envelope by the variations in the level of

filling said enclosure.

  Said window, the wall of which preferably has an externally convex profile, is thus exposed to the weight of the column of product above it, which results in an increase in the pressure within the liquid contained in said envelope. In practice, the pressure variation is a substantially linear function of the height of product above said window, as well as the surface of the window. And according to a preferential characteristic of the invention, it can be provided to vary the size of said window as a function of the storage height of the enclosure for which the device is intended, in order to obtain a pressure differential between lo the teas level and the high filling level which is substantially the same for storage enclosures of different heights, in order to simplify the processing

  of the signal obtained at the output of said pressure sensor.

  Of course, the pressure differential between the teas level and the high level can also be determined with a view to choosing an adequate pressure sensor and the characteristics thereof, such as its optimum resolution range. Naturally, other parameters such as the density of the product to be stored can also contribute to determining the

size of the window.

  According to another advantageous characteristic of the invention, said device has a generally cylindrical shape of circular section making it possible to mount it in a storage enclosure crossing a wall thereof; which makes it very easy to install on all types of new storage enclosures or already in service, and very easy to dismantle and reassemble for replacement purposes and / or

of maintenance.

  And in a preferred embodiment, the device comprises a front part and a rear part connecting end to end internally constituting a chamber in which the pressure sensor is mounted, and the front part presents a recess on a part of its length, in communication with a conduit opening into said chamber, a tubular element of flexible and substantially non-extensible material being threaded onto said front piece so as to hermetically seal said recess by forming above it the window with a flexible wall facing towards top, said casing being constituted by said recess, said tubular element and said conduit closed at the outlet by the head

  said pressure sensor and an associated seal.

  The pressure sensor is preferably a model supplied with very low current, for example of the order

  of 5 volts in direct current and lOmA.

  These and other features and advantages of the invention will become more apparent in

  the following description and the accompanying drawings, in

  which: Fig. l is a schematic view in vertical axial section of an embodiment of a device according to the invention; Fig. 2 is a cross-sectional view along line II-II of FIG. l; Fig. 3 is the same view in axial section as FIG. l, but partial, representing the same device fitted with an accessory; and Fig. 4 is a schematic sectional view illustrating the mounting of the device in the wall of a silo. As it appears in the drawings, the device s 1 according to the invention has a generally cylindrical shape of circular section, with a base part intended to be mounted through the wall P of a storage enclosure, as illustrated in FIG. 4, and a distal portion 1b intended to project substantially at

  the horizontal inside said enclosure.

  The body of the device is essentially formed of two front and rear pieces of rigid material, respectively 2 and 3, which are screwed tightly one at the end of the other, internally forming a

room 10.

  The front part 2 is a cylindrical block having first and second shoulders 22 and 23 in its rear part. It has a recess 20 above which is limited to a certain distance from its front end and to a certain distance from its first shoulder 22. As shown in FIG. 2, the recess 20 is defined transversely along a sector, here of the order of 120, preferably symmetrical with respect to the axial vertical plane Y-Y. The recess 20 communicates

  with the chamber 10 by an axial duct 21.

  A tubular element 4 made of flexible but substantially inextensible material (being for example a portion of polyvinyl chloride tube of Shore hardness of the order of 50-60 and a thickness of the order of 2.5 mm) is threaded tightly overlapping on the block 2, from the front end thereof and up to the first shoulder 22. It is shown here fixed in a sealed manner on the block 2 by means of two crimping ferrules 24. The tubular element 4 therefore closes hermetically the recess 20 constitutes above it a window 40 oriented upwards. The recess 20, the tubular element 4 and the conduit 21 define a completely closed casing 11 which is filled with an incompressible liquid, for example glycol water, in direct contact with the head of a pressure sensor 5 sealing

  sealingly with a seal 25 said conduit 21.

  The body of the pressure sensor 5 is housed in the chamber 10 which communicates towards the rear with a conduit 30 for passage of electric cable, provided with

outlet of a cable gland 31.

  The pressure sensor 5 is preferably a miniature model supplied with very low current, of the order of 5 volts for example and 10 mA, for example a model from the 40PC series in the company's catalog.

"Honeywell".

  In operation, the window 40 is subjected to the weight of the column of product resting on it, which results in a substantially proportional increase in pressure in the liquid inside the envelope 11. And even if in the case of pulverulent or granular products, it is not a strictly cylindrical column, but rather slightly flared upwards, its weight and consequently the increase in pressure which result from it remain functions substantially linear with respect to its height. The pressures detected by the pressure sensor 5 between the pressure correspond to the vice state and to the full state of the considered storage enclosure can therefore easily be converted into intermediate filling levels. Of course, if variable parameters such as the ambient temperature, the evolution of the humidity rate of the stored product, etc., can advantageously be taken into account in the processing of data signals from

pressure sensor 5.

  With the exemplary embodiment shown, the weight of the column of product resting on the window 40, and consequently the increase in pressure which results therefrom in the envelope 11, is substantially proportional to the longitudinal dimension of the said window. This is taken advantage of, according to another characteristic of the invention, so that in a whole set of silos or storage enclosures, the pressure differential between the full state and the vice state is substantially the same everywhere, independently the storage height of each unit. This has the advantages that data processing can be facilitated, that a single model of pressure sensor can be chosen for all the units, and that this can be used within its range of

maximum resolution.

  A simple way to modify the length of window 40 is shown in FIG. 3. This is one of a set of more or less long rings screwed onto the block 2 provided for this purpose with a thread between its first and second shoulders 22 and 23, to come over the window 40 on a specific part

of its length.

  Fig. 4 illustrates by an example ['extreme simplicity of implantation of a device according to the invention as described above, attempted in new installations than already existing. I1 indeed suffices to fix the base part la in a mounting of

  support S of the bulkhead type, and to arrange this

  ci crossing the wall (P) of the enclosure

storage to equip.

Claims (1)

  l) device for measuring the filling level of a storage enclosure for grain or powder products, characterized in that it comprises a casing (ll) which is substantially non-expandable and filled with an incompressible liquid, which casing (ll) has a window (40) closed by a flexible wall and is intended to be placed in the lower part of said enclosure with said window (40) oriented upwards, facing the gravity vector i as well as a pressure sensor (5) intended for transform into pressure signal the pressure differences generated in the liquid in said envelope (ll) by the   variations in the filling level of said enclosure.   2) Device according to claim l, characterized in that the wall of the window (40) has a externally convex profile.   3) Device according to claim l or 2, characterized in that the pressure sensor (5) is a   model supplied with very low current.   4) Device according to one of claims l a   3, characterized in that it further comprises means making it possible to modify the size of said window (40) as a function of parameters such as the height of   storage of the enclosure for which it is intended.   ) Device according to one of claims l a   4, characterized in that it has a general cylindrical shape of circular section allowing it to be mounted in a storage enclosure crossing a - wall (P) thereof.   6) Device according to claim 5, characterized in that it comprises a front piece (2) and a rear piece (3) connecting end to end internally constitute a chamber (10) in which is mounted the pressure sensor ( 5), and in that the front piece (2) has a recess (20) over a portion of its length, in communication with a conduit (21) opening into the chamber (10), a tubular element (4) in flexible and substantially non-extensible material being threaded onto said front piece (2) so as to hermetically seal said recess (20) by forming above it the window with a flexible wall facing upwards (40), said envelope (11) being constituted by said 1S recess (20), said tubular element (4) and said conduit (21) is closed at the outlet by the head to said pressure sensor (5) and an associated seal (25).   7) Device according to claim 6 and claim 4, characterized in that it further comprises a set of rings (6) of different lengths, intended to be passed and screwed on the piece (2) to come over said window (40) over part of its length in order to modify its size.