FR2505490A1 - Volumetric doser for measuring sugar beet sugar content - has single platform for beaker and calculator to determine weights or volumes of liquid mixture constituents to calculate sugar content - Google Patents

Abstract

A beaker (17) on the platform (12) of a balance (22) is located in a glass cabinet with a door. The balance provides weight signals for a calculator (30) to which a series of indicators (10) are connected to signal operational conditions. Two tubes (42,43) are positioned above the beaker to feed a lead sub-acetate from a reservoir (41) or to feed sugar beet puree from a second reservoir. The puree is fed into a burette (20) where an upper electrode (23) which is adjustable in height signals liquid quantity to the calculator. A second electrode (25) below the first provides a signal for the calculator to shut off a solenoid valve (50) providing a high flow. The top electrode is used to control a low flow rate valve (51). The calculator controls a third solenoid valve (52) to release the burette contents into the beaker. The calculator determines weights of the beaker and liquids from which it determines the sugar content in sugar beet.

Description

 The present invention relates to a volumetric proportional dosing machine for laboratory use and to a weighing-dosing method.

 Such a metering device is used to make a mixture of two products, including at least one liquid, while respecting between them a determined weight-to-weight or weight-to-volume proportion.

 This is for example the case, in the sugar industry, during the process of receiving a load of beets, and more particularly during the laboratory analysis of the sugar content of a representative sample of loading. This sample is usually in the form of a beet puree, called grating.

 To allow the precise determination of the sugar content of the grating, the latter is mixed with lead subacetate, of determined density, the volume of lead sub-acetate added having to be proportional to the weight of the grating.

 A proportioning metering device has already been proposed allowing this mixture to be produced.

 This metering device, placed in an enclosure closed by a door, comprises a beam balance, one of the ends of which carries a tray on which the grating is placed. The second end carries an electrode which is inserted into a burette.

 A set of solenoid valves controls the admission of liquid into the burette, the electrode carried by the flail being adapted to stop the flow of liquid in the burette.

 The burette has a shape specially designed to ensure a determined relationship between the height of the electrode, that is to say the weight of the grater, and the volume of liquid admitted into the burette.

 The burette is then emptied into a beaker into which the grating is also poured. There is then in the beaker a mixture of beetroot-lead sub-acetate in a proportion of weight of mash-volume of sub-acetate determined.

 Although this type of dispenser can still be satisfactory, it nevertheless has several shortcomings.

 In particular, the complex structure of this metering device imposes both the density of the lead sub-acetate used as well as the average admissible grating weight and the range around this average weight. Indeed, the shape of the burette determines these three elements and more particularly the range, around the average admissible weight of grating, is made very low (of the order of 1 g for 40 g of average weight) by the special shape given with the burette to allow dosing as precise as possible.

 The person responsible for dosing must therefore have 40 + 1 g very precisely on the scale pan, in this example.

 In addition, a dosing operation gives rise to various manipulations: grating placed on the tray and then transposed into the beaker, sub-acetate automatically passing through the burette to feed the beaker. This results in a significant loss of time if one takes into account the fact that a large number of assays must be carried out, during a limited time. This also results in risks of handling errors which are far from negligible, having regard to the precision of the dosage generally required.

 The present invention firstly relates to a proportioning metering device which overcomes the aforementioned drawbacks.

 To this end, the present invention provides a volumetric proportioning proportioner of the kind comprising, in an enclosure closed by a door, a balance, a burette of predetermined volume, a liquid inlet and a set of solenoid valves controlling the flow of liquid, doser characterized in that the balance is of the single-pan type and is suitable for receiving a beaker into which the liquid is poured directly, in that a locking-unlocking device is adapted to block said door, and in that the dosing device comprises a digital computer coupled to said balance, to said set of solenoid valves and to said locking-unlocking device.

 The dispenser according to the invention is therefore more convenient to use and has a much improved flexibility of use compared to the dispenser of the prior art. Indeed, grating and lead sub-acetate are immediately found mixed in the beaker and the aforementioned manipulations are therefore eliminated.

On the other hand, the structure of the metering device according to the present invention absolutely does not impose a proportion of grating weight-volume of sub-acetate, nor of density for the latter. Finally, the presence of a locking-unlocking device makes it possible to avoid handling errors that may be committed during the various weighings.
The present invention also relates to a weighing-dosing process making it possible to add to a first component which is placed in a first container, a second liquid component while respecting, between said components, a determined proportion.

 This method is particularly characterized in that it comprises the operations consisting in: weighing the first component; have the result of this weighing taken into account by a computer so that this computer can calculate the final weight of the mixture to be obtained; flow, using a set of solenoid valves, the second component into the container; stop this flow when the weight of the mixture in the container reaches said final calculated weight.

 Thanks to these provisions, the method according to the present invention makes it possible to carry out the dosage automatically and without intervention from the outside. The risk of handling errors is therefore practically eliminated.

In addition, and preferably, the method according to the present invention also comprises a series of preliminary operations intended to determine the density of said second component, this series of preliminary operations comprising the operations consisting in weighing a second container of predetermined volume; have the result of this weighing taken into account by a computer; pouring a predetermined amount of the second component into the container; weigh this amount of the second component; have the density of the second component calculated by the computer; save the said density in the computer
Thanks to this arrangement, the density of the second component is thus cyclically controlled, thus making it possible to avoid errors due to a variation in the concentration of the second component.

 Advantageously, the method according to the present invention is supplemented by the operations consisting in locking a door of an enclosure in which said first container is located to prevent access to the latter before said weighing operation of the first component; unlock-said door after said stopping the flow of liquid when the weight of the mixture in the container reaches said final calculated weight.

 Handling errors during weighing operations are thus avoided.

The characteristics and advantages of the present invention will become apparent from the description which follows, with reference to the accompanying drawings in which
Figure 1 is a schematic perspective view of an embodiment of the dispenser according to the present invention;
FIG. 2 is a block diagram showing the functional relationships of the elements of an embodiment of the present invention.

 According to the embodiment chosen and shown in FIG. 1, the metering device comprises a glazed enclosure 10 inside which is placed a box II and the plate 12 of a single plate electronic balance 22 (FIG. 2). The metering unit also includes an enclosure 13. On the front face 14 of the enclosure 13, various action members and indicators are arranged, which will be described in detail below. The glazed enclosure 10 comprises a sliding door 15 which can be locked by means of an electromagnet 16.

A beaker 17 is placed on the pan 12 of the balance 22.

 We will now describe, with reference to FIG. 2, the elements of the metering device which are housed in the box 11 and the enclosure 13.

 Generally, the metering device according to the present invention comprises a burette 20 of determined but adjustable volume, a computer 30, the single-pan balance 22, a set of conduits 40 controlled by solenoid valves 50, 51, 52, 53 and 54, a series of indicators 60, a set of push buttons 70 and a set of coding wheels 80.

 An electrode 21 coupled to the computer 30 is placed in the burette 20 near its lower end 26. An electrode 23, adjustable in height, is coupled to the computer 30 and placed in said burette 20 and below its upper end 24. A electrode 25, coupled to the computer 30 is arranged in said burette 20 and below said electrode 23 adjustable in height.

 We will now describe the set of conduits 40 and the solenoid valves controlling the circuit and the flow of lead subacetate in the latter.

 A tank (not shown), containing lead subacetate is placed under load with respect to the metering device and a pipe (not shown) connects the tank to the metering device. The connection point, that is to say the entry of liquid into the metering device, is shown in FIG. 2 at 41.

 A duct 45, called the first duct, is disposed between the liquid inlet 41 and the lower end of the burette 20 and a first high-flow solenoid valve 50 is disposed there in series. A first low-flow solenoid valve 51 is disposed as a bypass of the high-flow solenoid valve 50.

 A conduit 44, called the second conduit, is connected to the lower end of the burette 20 and opens out above the plate 12 of the balance 22, and a solenoid valve 52 is arranged there in series.

 A conduit 46, called the third conduit, is disposed between the liquid inlet 41 and the end of the second conduit 44, opening above the platform 12 of the balance and a second solenoid valve 53 at high flow rate is arranged there in series .

 A conduit 43, called the fourth conduit, is connected to the liquid inlet 41 and opens out above the plate 12 of the balance 22 and a second low-flow solenoid valve 54 is arranged there in series.

 The solenoid valves 50 to 54 are controlled by the computer 30, this being represented, in FIG. 2, by the arrows in accented lines. The electromagnet 16, allowing the blocking of the door 15 of the glazed enclosure 10, is also controlled by the computer 30. In addition, an electrical contact 18 disposed near the door 15 and coupled to the computer 30, allows to the latter to know at any time, whether the door 15 is open or closed.

 Three push-buttons 71, 72, 73 are arranged on the front face 14 of the enclosure 13. The push-button 71 controls a calibration operation, the push-button 72, a taring operation and the push-button 73 controls the admission of the liquid. The set of coding wheels 80 comprises a first series 81 of coding wheels making it possible to introduce into the calculataur 11-weight of the beaker 17. A second series of coding wheels 82 makes it possible to adjust the threshold for closing the solenoid valve 53 and of the opening of the solenoid valve 54. Finally, a coding wheel 83 makes it possible to introduce the range of admissible weight around the average weight which is, in this example, 40 g.

 The balance 22 is coupled with the computer 30, this being represented by the arrow 31.

 At the output of the computer, a series 60 of indicators makes it possible to know either the stage of the operating cycle or the possible fault which has appeared during operation.

According to the embodiment shown, the following stages of the operating cycle are displayed by the indicators 61 to 66
- indicator 61: ready
- indicator 62: taring
- indicator 63: liquid intake
- indicator 64: end of operation
- indicator 65: calibration
- indicator 66: sample
Any faults that may appear during operation are displayed by indicators 91 to 96
- indicator 91: door
- indicator 92: stability
- indicator 93: beaker outside the norm
- indicator 94: not enough samples
- indicator 95: too many samples
- indicator 96> theoretical weight too different from
practical weight.

 In the embodiment shown, by way of example, the metering device according to the present invention operates on two distinct cycles or series of operations: a so-called calibration cycle and a so-called normal running cycle.

The calibration cycle is actually a series of operations designed to determine the density of the liquid, so
on the one hand to check, at regular intervals, that the concentration of the lead sub-acetate solution does not deviate too much from a determined average value, in this embodiment: 2.5%,
- on the other hand to take into account, as precisely as possible, the variations of said concentration.

The calibration cycle includes the following operations:
- weigh a container of predetermined volume.

In the context of the embodiment shown, this amounts to placing a beaker 17 on the pan 12 of the balance 22, the beaker 17 having a volume greater than 100 cc
- have the result of this weighing taken into account by the computer.

In the context of the embodiment shown, this operation is carried out by storing in the computer 30 the weight of the beaker 17, thanks to the electronic coupling (arrow 31) between the single-pan balance 22 and the computer 30
- pour a predetermined amount of liquid into the container.

In the context of the embodiment shown, this operation is carried out by means of the solenoid valve 50, at high flow rate, which controls the admission of the liquid into the burette 20. When the level of the liquid in this burette reaches the electrode 25, the latter, which is coupled with the computer 30, controls through it, the closing of the solenoid valve 50, at high flow, and the opening of the solenoid valve 51, at low flow. The burette 20 continues to fill until the liquid level reaches the electrode 23, which controls, by means of the computer 30, the closing of the solenoid valve 51. There is then, in the burette 20, exactly 100 cc of liquid. The computer 30 then controls the opening of the solenoid valve 52. The liquid contained in the burette 20 pours into the beaker 17 until the level of the liquid in the burette 20 reaches the electrode 21. The latter causes the solenoid valve 52 to close, by means of the computer 30. There is then 100 cc of liquid in the beaker 17;
- weighing said predetermined quantity of liquid.

 In the context of the embodiment shown, this operation is carried out automatically, as soon as the liquid has been transferred 'from the burette 20 into the beaker 17, since the latter rests on the pan 12 of the balance 22.

The computer can determine the weight of the liquid since it has in memory the weight of the beaker 17;
- have the density of the liquid calculated by the computer.

The computer can carry out this operation since it has in memory the weight of the liquid and the quantity of this liquid in the beaker (100cc);
- store this density in the computer. This operation is done automatically by the computer 30.

 In the context of the embodiment shown, the calibration cycle is made compulsory each time the device is switched on and after a predetermined number of dosing operations (for example fifty). To this end, the computer is adapted to prevent the carrying out of any dosing operation if it appears that a calibration cycle must be carried out.

 The normal walking cycle, during which a metering is carried out, will now be described.

 Before the start of the normal running cycle, the average weight of the beakers to be used during the dosing operations must be displayed on the one hand, by means of the coding wheels 81, and, on the other hand, by means of the wheel. 83, the range of permissible weight around the value of the average grating weight used (in the context of this example, 40 g).

This normal walking cycle includes the following operations consisting of
- weigh the container (the beaker which will be used for dosing).

In the context of the embodiment shown, this operation is carried out by placing a beaker 17 on the pan 12 of the scale 22 and pressing the push button 72 to initiate the taring operations;
have the computer 30 take into account the result of this weighing so that the computer 30 can take it into account during the following operations.

 This operation is carried out by storing in the calculator 30 the weight of the beaker 17. If this weight deviates too much from the average value displayed by means of the coding wheels 81, the indicator 93: "beaker outside the norm" comes into action and the flow of the following operations is stopped.

At this stage, the entire metering unit is tared
- weigh the first component (grating).

In the context of the embodiment shown, this amounts to introducing the grating into the beaker 17
- have the result of this weighing taken into account by the computer.

This operation is carried out by storing the grating weight that the computer 30 can determine since it has, in this example, the weight of the beaker used. The computer 30 then verifies that the intro duction rasping weight is within the determined range, around 40 g in this example, and displayed by the coding wheel 83
- have the computer 30 determine the volume of liquid to be added.

 The computer 30 performs this operation taking into account a proportionality factor volume of liquid grating weight.

 In the context of this example, the proportion to be observed is 165 cc for 40 g of grating.

 - have the computer 30 calculate, from said calculated volume and density, the final weight of the mixture to be obtained.

In the context of this example, the computer 30 performs this operation using the formula
P = (165 v + 40) P
40 where "P" e8t the final theoretical weight to be obtained, v is the density of the liquid determined during the calibration cycle and "p" is the grating weight read previously. The expression "165 v + 40" represents the total weight of solution to be obtained if exactly 40 g of grating is introduced into beaker 17.

 - run, thanks to the set of solenoid valves 53, 54 the liquid in the container (namely the beaker 17).

 This operation is carried out by pressing the push button 73 which controls the admission of the liquid. The computer 30 then controls the opening of the solenoid valve 53.

When the weight of the mixture contained in the beaker 17 reaches the weight P 'such that
P '= P - x where "x" is a threshold value in grams, displayed by the encoder wheels 82, the computer controls the closing of the solenoid valve 53 and the opening of the solenoid valve 54 at low flow rate.

 - stop this flow when the weight of the mixture in the container reaches the final calculated weight.

As soon as the computer reads on the scale 22 the weight
P, it closes the solenoid valve 54.

 In the context of the embodiment shown, if there is an excess of the weight as calculated beyond a determined range, the indicator 96 lights up and the operator knows that this is so. The dosage is therefore canceled. Otherwise, there is in the beaker a mixture of grating-sub-acetate of lead in the proportion of 165cc of sub-acetate of lead for 40 g of grating.

 The various status indicators 61 to 66 light up during the operations, so that the operator always knows the operation in progress. Likewise, indicators 91 to 96 make it possible to know the faults in the operating cycle.

 Advantageously, the computer 30 can be programmed to lock the door 15 of the enclosure 10 before the start of the calibration operations and before the start of the dosing operations, so that the measurements cannot be falsified following a false maneuver on the plate 12, during the weighing operations which mark out, both the calibration cycle and the normal running cycle. Of course, the door 15 is unlocked to allow the introduction, both of the beaker, and of the grating in the latter, at the appropriate time of the cycles in question.

 Of course, the present invention is not limited to the embodiment described and shown, but encompasses any variant.

 In particular, the dispenser described is capable, by its structure comprising a computer, of performing all types of dosages. Indeed, it is possible to provide for several arrivals 41 of liquids and the number of conduits and solenoid valves can be increased, thus allowing more complex dosages to be carried out, provided that the computer software 30 is modified accordingly.

 Likewise, the devices making it possible to enter and exit data from the computer can be modified and adapted to other uses than those described above. To this end, the addition of a programming console to the computer 30, making it possible to dialogue with the latter, does not depart from the scope of the present invention.

 It will be appreciated that the present invention is not limited to the dosing of a mixture of lead sub-acetate and grating, but encompasses all laboratory dosing applications in all fields where such a proportioning dosing machine can prove to be useful, as well as it appears from the appended claims.

Claims (17)

CLAIMS 1 - Volumetric proportioning proportioner of the kind comprising in a chamber closed by a door, a balance, a burette of predetermined volume, a liquid inlet and a set of solenoid valves controlling the flow of liquid, doser characterized in that the balance ( 22) is of the mono-tray type (12) and is adapted to receive a beaker (17) into which the liquid is poured directly, in that a locking-unlocking device (16) is adapted to block said door (15 ), and in that the metering device comprises a digital computer (30) coupled to said balance (22), to said set of solenoid valves (50,51,52,53,54) and to said locking-unlocking device (16).  2 - Proportioning proportioner according to claim 1, characterized in that a conduit (45), said first conduit, is disposed between said inlet (41) of liquid and the lower end of said burette (20).  3 - proportioning metering device according to claim 2, characterized in that a first high-flow solenoid valve (50) is arranged in series in said first conduit (45).  4 - Proportioning metering device according to claim 3, characterized in that a first low flow solenoid valve (51) is arranged in derivation of said first high flow solenoid valve (50).  5 - proportioning metering device according to any one of claims 1 to 4, characterized -in that a conduit (44), said second conduit, is connected to the lower end of the burette (20) and opens out above the weighing pan (12) of the scale (22).  6 - proportioning metering device according to claim 5, characterized in that a solenoid valve (52) is arranged in series in said second conduit (44).  7 - proportioning metering device according to any one of claims I to 6, characterized in that a conduit (46), said third conduit, is disposed between said inlet (41) of liquid and the end of said second conduit (44) opening above the weighing pan (12) of the scale (22).  8 - proportioning metering device according to claim 7, characterized in that a second high-flow solenoid valve (53) is arranged in series in said third conduit (46).  9 - proportioning metering device according to any one of claims 1 to 8, characterized in that a conduit (43), said fourth conduit, is connected to said inlet (41) of liquid and opens out above the plate (12) of the balance (22).  10 - proportioning metering device according to claim 9, characterized in that a second low-flow solenoid valve (54) is arranged in series in said fourth conduit (43).  II - Proportioning dosing machine according to any one of claims 1 to 10, characterized in that an electrode (21), coupled to said computer (30), is arranged in the burette (20) and in the vicinity of its lower end (26 ).  12 - proportioning metering device according to any one of claims 1 to 11, characterized in that an electrode (23), adjustable in height, and coupled to said computer (30), is arranged in said burette (20) and below its upper end (24).  13 - proportioning metering device according to claim 12, characterized in that an electrode (25), coupled to said computer (30), is arranged in said burette (20) and below said electrode (23) adjustable in height.  14-proportioning metering device according to any one of claims 1 to 13, characterized in that it comprises a first series of indicators (61,62,63,64,65,66) adapted to signal a series of states d '' a dosing cycle.  15r proportional dosing machine according to any one of claims 1 to 14, characterized in that it comprises a second series of indicators (91,92,93,94,95,96) adapted to signal a defect in a working cycle of the dosing machine.  16 - proportioning metering device according to any one of claims 1 to 15, characterized in that it comprises a set of devices (80) adapted to enter the computer -data specific to each dosing operation.  17 - Weighing-dosing process for adding a second liquid component to a first component that is put in a first container, respecting a predetermined proportion between said components, a process characterized in that it comprises the operations consisting to: weigh the first component; have the result of this weighing taken into account by a computer so that this computer can calculate the final weight of the mixture to be obtained; flow, using a set of solenoid valves, the second component into the container; stop this flow when the weight of the mixture in the container reaches said final calculated weight.  18 - Weighing-dosing process for adding to a first component that is put in a first container, a second liquid component, so that a proportion between the volume of the second component and the weight of the first component is respected , method characterized in that it comprises a first series of operations intended to determine the density of said second component and a second series of operations intended to achieve the aforementioned volume-weight proportion, said first series comprising the operations consisting in: weigh a second container of predetermined volume; have the result of this weighing taken into account by a computer; pouring into the container a predetermined amount of the second component; weigh this amount of the second component; have the density of the second component calculated by the computer; store said mass density in the computer; said second series comprising the operations consisting in: weighing said first component making the computer take into account the result of this weighing; have the computer determine the volume of the second component to be added; having the calculator calculate, from said calculated volume and said density, the final weight of the mixture to be obtained; causing the second component to flow through a set of solenoid valves into said first container; stop this flow when the weight of the mixture in the container reaches said final calculated weight.  19 - A method of weighing-dosing according to claim 17 or claim 18, characterized in that before placing said first component in said first container, it comprises the operations consisting in: weighing the first container; have the computer take into account the result of this weighing so that this computer can take it into account during the following operations.  20 - Weighing-dosing method according to claim 19, characterized in that it comprises the operations consisting in locking a door of an enclosure in which said first container is located, to prevent access to the container before and during said operation weighing the latter; unlock said door after the weighing operation of the latter.  21 - Weighing-dosing method according to claim 17 or claim 16, characterized in that it comprises the operations of locking a door of an enclosure in which is said first container to prevent access to the latter before said weighing operation of the first component; unlocking said door after said stopping of the flow of liquid when the weight of the mixture in the container reaches said final calculated weight.  22 - Weighing-dosing method according to claim 18, characterized in that it comprises operations consisting in locking a door of an enclosure in which is located said second container to prevent access to the latter, before said first series operations for determining the density of said second component; unlock said door. at the end of said first series of operations.