FR2840066A1 - Equipment for measuring the amount of grain in a silo, comprises rigid rod which supports a lower casing with pressure pin able to act on a pressure sensitive resistive sheet and signal pressure - Google Patents

Abstract

The equipment consists of a rigid hollow rod (2) which has a larger section (2a) and a smaller section (2b) supporting a case (3). A pressure pin (5) is inset on an upper flat face of the case such that under pressure from the grain above it presses through a covering material (4) against a sheet of pressure sensitive resistance sheet (6) supported by the end of the rigid rod (21). The signal is nearly a linear function of the grain height.

Description

2s

  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, ultrasound systems, mechanical scales or strain gauge systems 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 ensured. s An object of the invention has therefore been to provide a device for measuring the filling level of a chamber for granular or powdered 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 to operate only an extremely falble 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 on the one hand: a rigid body in which is placed on a support a force sensor with resistance sensitive to compression; and on the other hand an element presenting an external bearing surface, and [opposite to this an internal bearing surface intended to come into contact with said resistance force sensor to compress it against said support; said element being mounted on said body in such a way that a force exerted against said external bearing surface results in a compressive force on said resistance force sensor; said body with said element being intended to be placed in the lower part of said enclosure with said bearing surface external to said element oriented upwards facing the gravity vector; so that said resistance force sensor transforms into electrical signals the differences in force on said bearing surface generated by the

  variations in the filling level of said enclosure.

  said external support surface to said element, which is preferably substantially planar, is thus exposed to the weight of the column of product above it, which results in a compressive force

  acting on said resistance pressure sensor.

  In practice, the variation of this compressive force is a substantially linear function of the height of the product above said external bearing surface, as well as of the surface of this behind. And according to a preferential characteristic of the invention, provision may be made to vary the size of said external bearing surface as a function of the storage height of the enclosure to which the device is intended, in order to obtain a differential of said compression force between the teas level and the high filling level which is roughly the same for storage enclosures of different heights, in order to simplify the processing of the signal obtained at output from said pressure sensor. Of course, the differential of the compressive force between the teas level and the high level can also be determined with a view to choosing a force sensor with adequate resistance 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 general cylindrical shape of circular section enabling it to be mounted 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 body of the device comprises, beyond a basic part, a front part having a connection end from which it extends below by an advance forming the support plane for the sensor. by force, said element being a portion of tube coming to play with play on said connection end and having a wall above it constituting said external bearing surface, in which a finger is fixedly fixed, the lower end of which constitutes said bearing surface interior above

of the sensor.

  Said element is advantageously engaged on the connection end of said front part with the interposition of a seal ensuring a double function of sealing and compensation of the clearance provided in the connection. The resistance force sensor is preferably a model which only requires an extremely low current to operate, of the order of a few milliamps. These and other features and advantages of the invention will become more apparent in

  the following description and the accompanying drawings, in

  which: a Fig. l is a schematic view in horizontal axial section of an embodiment of a device according to the invention; Fig. 2 is a schematic view in vertical axial section of the same device as in FIG. l Fig. 3 is a cross-sectional view along line IIIIII of FIG. 2; Fig. 4 is the same view in axial section as FIG. 2, but partial, representing the same device fitted with an accessory; and Fig. 5 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 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, like the illustrates Fig. 5, and a distal portion intended to project substantially horizontally

inside said enclosure.

  The device consists essentially of a one-piece body 2 extended by a front element 3. The body 2, made of rigid material, has a part

  rear 2a correspond to the base part above

  mentioned, and bounded forwards by a shoulder 2c from which it is extended by a front part 2b. The section of the front part 2b, instead of being circular like that of the rear part 2a, forms a horizontal upper flat, as can be seen in FIG. 3. Beyond a connection end 20, the front part, 2b is cut out above, in the form of an advance 21 presenting a horizontal upper surface intended to constitute a support plane 22

  substantially at the level of the longitudinal axis X-X.

  On the other hand, an axial conduit 23 for the passage of an electrical connection cable crosses the body 2. It extends at the front in the form of a groove stroke 24 in the rear part of the support plane 22; and at its rear end, it conforms to receive a

cable gland 8.

  At its end before connection 20, the front part 2b has its section uniformly decreased externally over a certain length, up to a shoulder 25, so that a male end piece is thus formed to receive the element 3 without discontinuity outer surfaces of it and the part

before 2b.

  Element 3 essentially consists of a portion of tube closed at its front end and having

  externally the same section as the front part 2b.

  It presents, in the continuity of the upper horizontal flat thereof, a wall 30 thus defining horizontally a flat surface of external support S. As shown in the drawings, Fig. 2, the wall 30 is thickened in its front part or it has a hole in which is mounted integrally a finger 5 projecting inwardly and whose end

  lower defines an interior bearing surface s.

  Advantageously, and as can be seen in FIG. 2, the finger 5 is shoulder higher to form a head received in a corresponding counterbore from its receiving hole in the wall 30, with interposition of a joint 50, and it can be fixed

  secured to the wall 30 by screwing.

  The support plane 22 is intended to receive a resistance force sensor 6, which is in the form of a very thin pad constituting the sensitive part, extended by a connection tail, which is here oriented towards the groove 24 and the conduit 23. Such sensors essentially consist of a portion of relatively thick film whose electrical resistance decreases as a function of a compressive force applied to it. As an indication, the sensor used here can be a model called "FSR" for "Force Sensor Resistance" sold by the US company Interlink Electronic under the reference Part # 400. Note moreover that these components have the advantage of not requiring for their operation that an extremely low current

(some milliamps).

  The resistance force sensor 6 is held in place without constraint on the support plane 22 by a covering piece 4 which is fixed at the end of

  the connection end 20 of the front part 2b.

  The part 4 has a through hole through which the finger 5 comes through its bearing surface s in contact with the

resistance force sensor 6.

  According to the invention, a certain clearance is provided in the connection of the element 3 around the connection end 20, absorbed by the flexibility of a seal 26 which therefore has a double function. And in ['assembly of the device, it is the finger 5 engaged in the part 4 itself fixed to the front part 2b, which ensures the maintenance of the connection between this

behind and [element 3.

  In operation, the external support surface S of the element 3 is subjected to the weight of the column of product carried on it, which weight due to the loose aspect of the connection between the element 3 and the front part 2b results in a substantially proportional compressive force exerted by the interior bearing surface s of finger 5 on the sensor 6. 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 remains a function which is appreciably linear with respect to its height. The forces detected by the resistance force sensor between the pressure corresponding 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, variable parameters such as the ambient temperature, the evolution of the humidity level of the stored product, etc., can advantageously be taken into account in the treatment.

  data signals from sensor 6.

  With the example of embodiment shown, the weight of the column of product in abutment on the external bearing surface S. and consequently the compression force which results therefrom on the force sensor at resistance 6, wind substantially proportional to l 'area of said surface S. This is used, according to another. characteristic of the invention, so that in a whole set of storage silos or enclosures, the pressure differential between the full state and the vice state is substantially the same everywhere, regardless of the storage height of each unit. It follows from this as advantages that the data processing can be facilitated, that a single model of resistance force sensor can be chosen for all the units, and that this can be used within its range.

maximum resolution.

  A simple means for modifying the area of the external bearing surface S is shown in FIG. 4. I1 is one of a set of more or less long rings threading on the front part 2b, and advantageously locking in place by means of a quick fixing mechanism such as snap-fastening , to cover the surface S over a determined part of its length. As shown, the ring 7 is provided at its front end with a lip seal 70 to prevent the entry of susceptible material.

  to operate the device.

  Fig. 5 illustrates by an example the 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 2a in a mounting of

  support M of bulkhead type, and to arrange this

  ci across the wall (P) of the enclosure

storage to equip.

s 1

Claims (1)

REVENDIGATIONS   l) Device for measuring the filling level of a storage enclosure for grain or powder products, characterized in that it comprises on the one hand: a rigid body (2) in which is arranged on a plane. support (22) a resistance force sensor (6) sensitive to compression; and on the other hand an element (3) having an external bearing surface (S), and [opposite to this an internal bearing surface (s) intended to come into contact with said resistance force sensor (6) to compress it against said support plane (22); said element (3) being mounted on said body (2) in such a way that a force exerted against said external bearing surface (S) results in a compressive force (s) on said resistance force sensor (6 ); said body (2) with said element (3) being intended to be placed in the lower part of said enclosure with said external bearing surface (S) to said element (3) oriented upwards facing the gravity vector; so that said resistance force sensor (6) transforms into electrical signals the differences in force on said external bearing surface (S) generated by variations in the filling level of said enclosure.   2) Device according to claim l, characterized in that said external bearing surface   (S) said element (3) is substantially planar.   3) Device according to claim 1 or 2, characterized in that the resistance force sensor   (6) is a model supplied with very low current.   4) Device according to one of claims 1 a   3, characterized in that it further comprises means making it possible to modify the area of said external bearing surface (S) to said element (3) as a function of parameters such as the storage height of   the enclosure for which it is intended.   5) Device according to one of claims 1 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 the body (2) comprises beyond a base part (2a), a front part (2b) having a connection end (20) from which the el extends below by an advance (21) forming the support plane (22) for the sensor (6), ['element (3) being a portion of tube coming to engage with play on the connection end ( 20) and having a wall (30) above it constitute the external support surface (S), in which a finger (5) is fixedly fixed, the lower end of which constitutes said support surface   interior (s) above the sensor (5).   7) Device according to claim 6, characterized in that the resistance force sensor (6) is held in place without stress on the support plane (22) by a cover piece (4) coming to be fixed at the end of the 'end of connection (20) of the front part (2b) and having a passage for the finger (5).   8) Device according to claim 6 or 7, s Icaracterise in that said element (3) is engaged on the connection end (20) of said front part (2b) with interposition of a seal (26) ensuring a double sealing and play compensation function provided in the connection.   9) Device according to one of the   claims 6 to 8 and claim 4, characterized   in that it further comprises a set of rings (7) of different lengths, intended to be threaded on the front part (2b) of the body (2) to come into overlap with said external bearing surface (S) in said audit element (3) over part of its length so