FR2504650A1 - METHOD AND INSTALLATION FOR CONTINUOUSLY MONITORING AND ADJUSTING A SET OF GAS BOTTLE FILLING STATIONS - Google Patents

Abstract

Method and system for continuous monitoring and control of a group of filling stations for gas cylinders, for compressed or liquefied gas, having a carousel (200) for accommodating a multiplicity of individual filling stations (210), a cylinder feed and data recording station (100), a weighing station, a removal station (500) and control, computing and display devices (600). Subsequent comparison of the actual weight of a filled cylinder with its desired weight enables, on the one hand, subsequent control of each filling station and, on the other hand, the removal of empty or inadequately filled cylinders. Furthermore, the measured values transmitted by the weighing station are stored for the purpose of establishing the filling quantity of each filling station and the filling quantity of a group of filling stations, and subsequently re-recorded and evaluated for the purpose of determining systematic deviations of specific filling stations.

Description

 The present invention relates to a process for continuously monitoring and adjusting a set of filling stations for gas cylinders and an installation intended for the implementation of this process.

 Various installations are known for filling bottles with compressed or liquefied gas. More and more automation is sought there more often. But, despite the high rates allowed by this automation, it remains necessary to individually control the charge of each bottle after filling, so as to eliminate the insufficiently filled bottles. On the other hand, this control allows to realize a systematic excess or insufficiency of the gas charge. It must be possible to correct such deviations by adjusting the filling. However, such verification becomes very difficult with the use of a manege with a plurality of filling stations for a single chain of bottles. A control downstream of filling, where it is not possible to recognize the station who has filled the bottle being inspected, only determines the overall defect or excess of all stations. To adjust each station individually, it is necessary to carry out a check immediately after filling, before the bottle is ejected from its filling station.

Such a check cannot be carried out systematically for each bottle, otherwise the speed of the ride will be thoughtlessly slow. The precision of the adjustment is reduced accordingly, as well as the speed with which the correction correction is made.

 To overcome this drawback, the present invention provides a process for continuously monitoring and adjusting each filling station, using measurements carried out after the fact, downstream of the filling device, as well as an installation for work of this process.

 I1 consists in bringing the bottle close to a data taking station located upstream of a filling device, and ensuring the recording of the tare information of said bottle, admitting the bottle on a filling, the number of which has been previously registered, filling, transferring the filled bottle to a previously released weighing device located downstream of the filling device, measuring the weight of the bottle, restoring the tare information and number of stations recorded upstream of the filling station, compare the actual value of the weight of the bottle with the desired value so as to determine a default deviation or an excess of filling, determine1 from a series of measurements relating to bottles filled by the same station, the average deviation for each station considered, and finally adjusting each filling station so as to correct the systematic error thus revealed.

 On the other hand, the measurements provided by the weighing station can be memorized and subsequently restored, so as to know the total production of each station and the production of all the stations making up the carousel.

 A characteristic of the invention consists in determining the weight of the bottle, in advance1 from a succession of instantaneous measurements, before the weighing device has reached its equilibrium, by determining the average of said values. In this way, it is possible to evaluate the weight of the bottle in a very short time, compatible with the high rate of scrolling of the bottles on the chain.

 A characteristic of the method according to the invention also consists in periodically measuring the error provided by the weighing device, and in correcting the measurement of the weight so as to cancel the effect of said error.

 To implement this method, the invention provides an installation comprising a data taking station located near an intake device on the carousel, means for reading and memorizing the number of the filling station on which the bottle is admitted, means for weighing the bottle, calculation means, display means, and means for adjusting the filling stations.

Preferably, the weighing means consist of a load cell with a strain gauge from which is suspended a swing receiving the bottle to be weighed, and comprising a prestressing weight made integral with the swing in the absence of a bottle
Finally, the installation can also include means for ejecting empty or insufficiently filled bottles, so as to set apart the bottles whose gas load is less than a predetermined value.

Other characteristics and advantages of the invention will appear on reading the detailed description below, made with reference to the accompanying drawings, where
FIG. 1 is an overall diagram of the installation showing the sequence of different phases of the process and the arrangement of the means of implementation,
FIG. 2 is a view of the weighing device,
FIG. 3 is a graph showing the instantaneous value of the weight of the bottle as it can result from the measurement by the weighing device.

In Figure 1, are shown the intake and data taking station 100, the carousel 200 carrying all the filling stations, one of which has been shown at 210, the ejection station 300 outside the carousel , the weighing station 400, the station for ejecting empty or insufficiently filled bottles 500, as well as the calculation, control and display unit 600, which can for example be a microcomputer of the "micral" type
S.

 The first station 100 consists of an input conveyor 101, a data taking station 102 and an intake cylinder 103. The filling station 210 comprises a filling head 211 supplied with compressed gas or liquefied by an adjustment device 212 making it possible to admit a greater or lesser amount of gas into the bottle 213. A probe 214 makes it possible to recognize the filling station and to transmit the information on the station number. The ejection station 300 comprises a jack 301 pushing the bottle 302 on a transfer conveyor 303 intended to bring the bottle to the weighing station 400. Downstream of this weighing station, the ejection station for empty bottles 500 comprises an ejection cylinder 501, a lateral ejection conveyor 502 located opposite the cylinder 501, and an outlet conveyor 503. Finally, the control and calculation unit 600 is connected on the one hand to the data taking station 102, to the probe 214 and to the weighing device 400 from which it receives the information, and on the other hand to the filling adjustment device 212 and to the ejection cylinder 501, which it coordinates one and the other. A display panel 601 makes it possible to view a certain number of parameters relating to the operation of the chain, and a printing device 602 makes it possible to keep a record of the information supplied by the control and calculation unit 600.

 The bottle arriving from the inlet conveyor 101 is immobilized in position 104. There, a reading of the tare of the bottle is carried out, either automatically by any method of coding the information on the body of the bottle, or by an operator. reading the information on a tablet 105 set at the top of the bottle.

This information is transmitted to the data-taking station 102 and then to the control and calculation unit 600 where it is stored. The jack 103 is then actuated to push the bottle back onto the manege 200 where it is immobilized, for example in position 213 on one of the filling stations 210. It is charged there with a quantity of gas predetermined by the setting 212 according to the information provided by the control and calculation unit 600. During the filling period, the roundabout 200 rotates in the direction indicated by the arrows 20-1 or 202. At the end of filling , the bottle is in position 302 where it is ejected from the merry-go-round by the actuation of the jack 301. It is then conveyed to the weighing device 400. At the end of weighing the bottle arrives in position 504. If its weight, such as it has been determined at the weighing station 400, is insufficient, the control and calculation unit 600 activates the jack 501 which pushes the bottle back on the empty bottle ejection conveyor 502 for further processing to determine the causes of insufficient filling wise. If the weight is correct, the bottle continues on its way to the exit conveyor 503.

 FIG. 2 represents the weighing device 400. A swing 401, which receives on its plate 402 the weighing bottle 403, is suspended from a load cell 404 secured to a frame 405. The device used can be of the "ISe2" type. strain gauge, manufactured by the company "LA TELEMECANIQUE". Such a device automatically ensures the conversion of the measured weight into digital electrical information, directly usable by the command and calculation unit 600.

The lower part of the plate 402 can be made integral with a weight 405 resting on a fixed support 406 by means of a connecting device 407.

 In the absence of a bottle, the plate 402 occupies a high position such that the device 407 ensures the connection with the weight 405 and lifts the latter from the support 406. A prestressing of the load cell is thus carried out and in the absence of the bottle, by the weight 405.

When a bottle is loaded on the swing, the tray 402 lowers, the weight 405 rests on the support 406, and the device 407 separates the weight of the tray. The prestressing, thus eliminated in the presence of a bottle, made it possible to avoid vertical oscillations of the swing of too great an amplitude
Preferably, the prestressing weight also serves to determine the error provided by the weighing device, by periodic comparison between the actual value of the prestressing weight and the measurement provided by the load cell in the absence of a bottle on the swing. The difference, in more or less, thus estimated will be transmitted to the calculation and control unit 600 which, respectively, will subtract it or add it to the values of the weight of the bottle indicated by the device for all subsequent measurements, so to cancel the incidence of this systematic error.

 FIG. 3 represents the measurement of the weight supplied by the weighing scale 404. On the abscissa is plotted the time, on the ordinate, the measurement of the weight in kg. This measurement, which is the apparent weight of the bottle, varies according to the curve 700 shown in dotted lines. This measurement is not constant due to parasitic oscillations of the swing following the loading of the bottle. The apparent weight tends to stabilize around the value 701 after a very long time at the inertia of the balance mechanical balance. This time is too long in consideration of the high rate of scrolling of the bottles.

 It is therefore necessary to be able to evaluate this final value in advance, without waiting for the final stabilization of the whole. For this, the ISP2 load cell provides a series of measurement points 710, 711, 712 ... at regular intervals of 100 milliseconds. This series of instantaneous values is transmitted to the calculation and control unit 600 which evaluates their average, represented in the figure by the value 720, which is thus an approximation of the exact value 701. The number of measurement points is always the same ; it is chosen so that the total: loading time of the bottle on the tray + measurement time (number of measurement points X per interval between two points) + release time of the tray, remains, on average, less than the cadence of the bottles on the chain. In order to improve the accuracy of the measurement, the measurement points are only started to be recorded when the difference between the highest measurement and the lowest measurement remains less than a predetermined quantity. In the example of FIG. 3, if, for example, this maximum admissible deviation is fixed at 80 g, as represented by the arrow 730, it can be seen that the points 710 and 711 will not be taken into account, their deviation (120 g) being too large, while points 712, 713, 714 ... will be taken into account, because they remain within the tolerated limits.

 As a variant, it is possible to envisage calculating the average by a process, not digital as in the example described, but analog, where the smoothing of the curve 700 would be carried out, for example, by integrating electrical circuits.

 The value 720, estimate of the weight 701 of the bottle, is then compared by the calculation and control unit 600 to the desired value, equal to the tare of the bottle + the standard gas charge. The difference thus determined is memorized at the same time as the item number information previously transmitted by the sensor 214 at the time of filling. When a sufficient number of such differences are known for the same station, their average is determined, which will provide an indication of the drift provided by the filling station 212. In return, the latter can thus be readjusted immediately, and continuously , so as to cancel the difference noted.

 It is understood that the foregoing description refers only to a particular embodiment of the invention, and that many variants can be envisaged without thereby departing from the scope of the present invention.

Claims (9)

 1. continuous monitoring and adjustment process for a set of filling stations for compressed or liquefied gas cylinders, characterized in that it consists of  bring the bottle near a data taking station (100) located upstream of a filling device (210) and ensuring the recording of the tare information of said bottle,  admit the bottle to a filling station (210) whose number has been previously registered,  . proceed with filling,  . Transfer the filled bottle to a weighing device (400) previously released, located downstream of the filling device,  measure the weight of the bottle,  . restore the tare and item number information recorded upstream of the filling station,  compare the actual value of the weight of the bottle with the desired value, so as to determine a default deviation or overfilling,  determine from a series of measurements relating to bottles filled by the same station the average deviation for each post considered,  finally adjust each filling station so as to correct the systematic error thus revealed.  2. Method according to claim 1, characterized in that the determination of the weight of the bottle after filling is carried out in advance from a succession of instantaneous measurements carried out as soon as the bottle is admitted to the weighing device, and before that the latter has not reached its equilibrium, by determining the average of the values of said measurements, and provided that the difference between the maximum value and the minimum value of the series of values is less than a predetermined quantity.  3. Method according to one of claims 1 or 2, characterized in that it also comprises a periodic measurement of the error brought by the weighing device, measurement whose value is used to correct the measurement of the weight of the bottle, so as to cancel the incidence of the said error.  4. Method according to one of claims 1 to 3, characterized in that the measurements provided by the weighing station are stored and subsequently restored so as to know the total production of each station and the production of all stations.  5. Installation intended for the implementation of the method according to one of claims 1 to 4, of the type comprising  a carousel (200) having a plurality of individual filling stations (210),  a single device for admitting (100) the bottles to the carousel,  a single device for ejecting (300) the bottles leaving the carousel,  a weighing station (400) located downstream of the ejection device, characterized in that it comprises  - a data taking station (102) located upstream of the filling stations (210) allowing this to record the value of. the tare of the bottle,  - means (214) for reading and memorizing the number of the filling station on which the bottle is admitted,  calculation means (600),  display means (601),  and adjustment means (212) for filling stations.  6. Installation according to claim 5, characterized in that the weighing means (400) consist of a load cell (404jà strain gauge to which is suspended a swing (401) receiving the bottle to be weighed (403).  7. Installation according to claim 6, characterized in that the weighing means comprise a weight (405) of prestressing secured to the swing in the absence of bottle, and removed upon admission of the bottle.  8. Installation according to claim 7, characterized in that the prestressing weight also serves to determine the terror provided by the weighing device, by periodic comparison between the actual value of the prestressing weight and the measurement provided by the weighing scale in the absence bottle on the swing.  9. Installation according to one of claims 5 to 8, characterized in that it also comprises means for ejecting (500) empty or insufficiently filled bottles, cooperating with the weighing means, so as to isolate the bottles whose load gas is less than a predetermined limit value.