FR2797046A1 - Differential volumetric feeder for precision dosing of small quantities of liquids has secondary chamber forming extension to dosing chamber - Google Patents

Abstract

Feeder consists of a hollow body (1) with a dosing chamber (2), inlet (4) and outlet (5) channels, and a cylindrical piston (3) with a lengthwise distribution groove (6). Feeder consists of a hollow body (1) with a dosing chamber (2), inlet (4) and outlet (5) channels, and a cylindrical piston (3) with a lengthwise distribution groove (6). The dosing chamber is extended at one end to form a coaxial secondary chamber (7) of smaller diameter which receives a small diameter projection (10) on the end of the piston. The piston is able to rotate as it moves up and down in the dosing chamber, and its distribution groove is located in its large diameter section. Above the dosing chamber the feeder has a washing chamber (12) of slightly greater diameter than the large diameter section of the piston and has an inner perforated partition (14) forming a cavity linked to a washing fluid channel (16) with a shut-off valve (17).

Description

 The invention relates to a differential volumetric dosing device, in particular intended to deliver a determined and dosed amount of liquid, especially for volumes typically between the microliter and the milliliter.

Many industrial sectors require the implementation of precise dosing and low amounts of liquid, especially in the fields of pharmaceutical, cosmetic, chemical and also agro-food industry.

In order to perform the dosing of small amounts of liquid, a device has been proposed that uses the principle of a metering using an alternating stroke piston within a cylindrical chamber, the piston stroke being of course depending on the volume to be dosed. In fact, the determination of the volume to be assayed is a function of either the length of the piston stroke within the cylindrical chamber or the diameter of said metering chamber.

However, it is observed that if the stroke of the piston is decreased too much, it imposes a kinematic piston or the quasi-perfect cylindrical chamber, and which has no derivation in time. In fact, experience shows that one encounters problems of reproducibility and hence of precision in terms of the quantities dosed and delivered.

If instead we choose to reduce the diameter of the chamber and therefore the piston, it is observed that below a diameter of a value typically close to 6 millimeters, the manufacturing cost of the corresponding material increases drastically, and moreover , the device proves to be very fragile, incompatible with a good number of applications.

Among these various devices, one of them uses a piston provided on its periphery with a longitudinal distribution groove, said piston sliding in a hollow cylinder defining the metering chamber. The implementation of this type of device, given the degree of precision of realization of the elements, makes it possible to overcome any seal. The rise of the piston in the cylinder causes the aspiration of the liquid to be dosed from a pipe opening into the body of the cylinder. At the end of the ascending stroke, the piston is rotated by a determined angle, for example 180 degrees, in order to match said groove with another pipe, also opening into the body of the cylinder, and located in a position diametrically opposite to the The downward stroke of the piston induces the ejection of the liquid out of the peripheral groove in this delivery pipe or ejection. At the end of the stroke, the piston is rotated again by 180 degrees, and the cycle is repeated.

If this particular architecture makes it possible to satisfy the requirements in terms of dosage, it nevertheless has the following drawbacks. First, an impurity in the groove can induce the alteration or blockage of the suction or ejection of the liquid contained therein. In addition, such an impurity can cause premature wear of the piston or cylinder. Finally, for certain applications, pharmaceutical or agro-food in particular, this type of device is subject to severe hygiene and sterility, thus requiring the implementation of easily decontaminable organs. The presence of a groove as well as the intake and exhaust pipes induces a relatively rapid contamination of the piston, and corollary a decontamination made more difficult, because of the existence of angles, nooks, intersections.

When it comes to dosing very small quantities of liquids, typically micron or submicron, the phenomenon of inertia and the implementation of piezoelectric quartz is used. This principle of dosing is particularly implemented at the level of inkjet printers. However, such a principle can not be used for dosages of greater quantity between the micro and the milliliter. Indeed, the nano or the pico assay, implements sub-multiples of the micro-assay. To obtain a microdose, it will be necessary to add nano or pico-doses, which consequently causes an addition of errors.

In addition to this dosing function, the industry also requires a simultaneous washing and sterilization function of this type of device, without involving any disassembly of the constituent organs.

Among the washing and decontamination devices of a known metering system, one of them uses a pump provided with a cleaning chamber contiguous to the cylinder of the piston, and inducing the injection of cleaning solvents. hot and / or cold and vapors under pressure. However, insofar as there is no stirring, experience shows that this cleaning system is relatively ineffective, especially when this washing phase occurs after dosing of relatively high viscosity fluid. Moreover, if these two functions, respectively dosing and washing are today provided independently of each other, no device does not collect them simultaneously, in any case, with the desired efficiency.

The object of the invention is therefore to propose a device capable of offering the two functions simultaneously, respectively dosing quantities of liquids substantially between the microliter and milliliter, and cleaning and sterilization on site, called by the profession according to the expression <I> </ I> CIP / SIP <I> </ I> for <I> </ I> cleaning <I> in place / </ I> sterilization <I> in place. </ I >

This differential volumetric dosing device comprises: a hollow body, defining a cylindrical metering chamber, at the level of which respectively open a pipe for supplying and delivering or ejecting the liquid to be dosed; a cylindrical piston, whose external diameter corresponds to the clearance close to the internal diameter of the metering chamber, and slidable within said chamber, the piston being provided at its periphery with a longitudinal distribution groove, likely to come opposite the opening opening, respectively of the supply line and delivery or ejection.

This device is characterized in that the metering chamber is extended at one of its ends by a secondary chamber, coaxial with the latter, but of internal diameter less than the internal diameter of said metering chamber; # and in that the piston has an extension, coaxial with the latter, also of external diameter less than the outer diameter of the piston and corresponding to the clearance, to that of said secondary chamber; said piston being capable of being driven by an upward and downward translation movement within the hollow body, simultaneously or not with a rotational movement. In other words, the metering device according to the invention performs differential dosing, this notion of differentiality being inherent in the implementation of a double diameter piston at the level of the metering chamber.

According to the invention, the longitudinal distribution groove is located at the periphery of the zone of the piston having the largest diameter. According to another characteristic of the invention, the metering chamber is surmounted at its other end by a chamber. washing, also coaxial, inner diameter slightly greater than the outer diameter of the piston, and provided with a perforated peripheral wall, at which is conveyed by a pipe a washing fluid, said pipe being closable, especially during the phases of dosing, by means of a valve.

Advantageously, the perforations are distributed over all or part of the height of the washing chamber.

According to another characteristic of the invention, the secondary chamber extending the metering chamber is provided at its lower end with a pipe, closable by valve, and capable of communicating said chamber with the outside, and to allow the evacuation of the washing fluid.

The manner in which the invention can be realized and the advantages which result from it will emerge more clearly from the exemplary embodiment which follows given by way of indication and not limitation in support of the appended figures.

Figure 1 is a schematic representation in longitudinal section of the metering device according to the invention, shown in intermediate dosage position.

Figure 2 is an analogous representation of Figure 1, but showing the metering device in the washing position or sterilization.

Figures 3 to 7 are also diagrammatic representations in cross section showing the various stages of positioning of the piston relative to the hollow body during a dosage phase.

FIG. 1 therefore shows a schematic view in longitudinal section of the volumetric dosing device according to the invention. Basically, this metering device is based on the principle of actuating a piston within a cylinder, said cylinder defining the metering chamber. More specifically, the cylinder is defined by a hollow body (1), defining a metering chamber (2).

Within this hollow body (1), a piston (3) is able to translate, in the example described, in an upward or downward movement. In order not to unnecessarily overload the figures, the member ensuring the translation or rotation of the piston has not been shown. As can be clearly seen, open at the hollow body, two pipes respectively supply (4) and discharge or ejection (5) of the liquid to be dosed. These two pipes open at the same height, but in the example described, form between them an angle of 180 degrees.

According to one characteristic of the invention, the piston (3), whose diameter D1 corresponds to the clearance to the internal diameter of the hollow body (1), has at its periphery a groove or longitudinal channel (6), whose width is a function of the operating mode of said piston in pumping mode, and as described below in more detail. According to one characteristic of the invention, the hollow body (1) extends at its lower end by a cylindrical zone, coaxial with the metering chamber (2), but of lower internal diameter, defining a secondary chamber (7). . As a corollary, the piston (3) has at its lower end a cylindrical extension (10), coaxial with said piston (3), and whose outside diameter D-2 corresponds to the clearance, to the inside diameter of said secondary chamber ( 7).

In this way, since the diameters D1 and D2 are clearly defined and reproduced at these different members, the volume generated at the metering chamber (2) becomes in the same way perfectly defined and reproducible. Indeed, since the diameter j2 of the extension (10) is known accurately, the volume occupied by said extension (10) within the metering chamber (2) also becomes perfectly definable according to the height of the race of the piston (3) within the hollow body, since, by hypothesis, D-1 is itself also perfectly known.

In fact, it will be described in connection with Figures 3 to 7, the operating mode of the metering device according to the invention.

It is thus shown in Figure 3, the piston (3) at its maximum downstroke. In this configuration, the groove (6) is positioned opposite the supply pipe (4) of the liquid to be dosed and, as a corollary, the metering chamber (2) is completely filled by the piston. The ejection pipe (5) is closed by the piston: During its upward stroke, there is suction of the liquid within the metering chamber for a volume, which is a function of the diameters D1 and D2 mentioned above, and the height of the upward stroke of said piston. FIG. 4 shows the piston at its maximum stroke in the dosing mode. It then undergoes a rotation of a given angle, for example 180, as shown in the figure, at the end of the upward translation. However, this rotation can be performed in synchronism with the translation of said piston, in the event that the groove has a width sufficient to not lead to the obstruction of the outlet area of the supply line (4) of the liquid to be dosed in the dosing chamber (2).

At the end of rotation (Figure 5), the groove (6) is then facing the ejection pipe or distribution (5) of the liquid thus metered. As a corollary, the pipe (4) is closed by the piston.

The piston is then subjected to a downward translation, so as to drive the liquid contained in the metering chamber (2), up through the groove (6) at the level of said discharge or ejection pipe (5) until the downward translation of the piston reaches maximum travel, as shown in FIG. 6.

A new rotation of the piston 180 in the example described makes it possible to restart the cycle by repositioning the groove (6) with respect to the inlet orifice of the supply line (4).

It will be noted that during this metering mode, the secondary chamber (7) is systematically closed by the extension (10) emanating from the piston (3).

According to another characteristic of the invention, the hollow body (1) is surmounted by a zone that is also cylindrical (13), defining a washing and sterilization chamber, the diameter of which, as can be clearly seen, notably in FIG. 2, is greater than the maximum outside diameter p1 of the piston (3).

This washing and sterilizing chamber (12) is also defined by means of a cylindrical partition (14) coaxial with the metering chamber. This partition (14) is perforated with through openings (15), to allow the injection of the washing fluid and sterilization therein, said fluid being conveyed through a pipe (16) closable by means of a valve, for example a solenoid valve (17).

Meanwhile, the lower end of the secondary chamber (7) mentioned above is extended by a pipe (8) for discharging said washing fluid and sterilization, this pipe being closable by means of a valve (9). The implementation of these various members will thus make it possible to optimize the washing and the sterilization of the piston (3), the metering chamber (2) as well as the supply (4) and evacuation (5) lines. liquid to be dosed.

Thus, in washing mode, the piston (3) is first removed manually or automatically at the maximum of its upward stroke, as shown in FIG.

In this configuration, it is observed that the periphery of both the piston (3) and its extension (10) is no longer in contact with any of the guide walls of the hollow body (1).

The cleaning fluid, in particular steam, hot water, alcohol, solvent, etc., is introduced in particular through the pipe (16) and the feed pipe (4), within the total volume thus defined by the washing chamber. and the metering chamber, then collected by the pipes (8) and (5).

The piston is lowered so that the lower end of the extension (10) comes to close the secondary chamber (7). The valve (9) closing the evacuation pipe (8) is then closed and the piston (3) is raised, causing a depression within the total internal volume defined above. This depression thus causes a rapid entry of solvent, and generally of the washing liquid into the secondary chamber (7), this rapid and sudden entry occurring precisely at the moment when the end (10) of the piston leaves said secondary chamber ( 7). The valve (9) must remain closed during this implosion phase. In fact an energetic agitation of the liquid and the washing fluid present inside the volume defined by the dosing and washing chamber is carried out, thus allowing by its mechanical effect, to clean the impurities in situ, optimizing the so the washing function. At the end of the phenomenon, as short as it is, the valve (9) is open to allow the evacuation of the cleaning effluent.

The repetition of this cycle a certain number of times thus makes it possible to completely wash both the piston (3) and its extension (10), but also the metering chamber and the supply (4) and discharge (5) pipes. liquid to be dosed. The sterilization phase itself is then carried out, consisting mainly in subjecting the piston and the various chambers, the piston being in maximum upward translation position, to a flow of pressurized vapor at 130 ° C. for a definite period of time, defined by the standards in force to achieve sterilization. It is therefore conceivable the whole of the interest of the dosing device according to the invention.

Firstly, the high precision of the metering is noted thanks to the differential function inherent in the double diameters, M and D2 respectively of the piston and its extension. In this way, it thus becomes easy to play on larger piston displacement races, thereby facilitating the accuracy of the measurements without increasing the cost of manufacturing the various elements involved in the constitution of this device, nor increasing its fragility. mechanical.

At the same time, the simultaneous function within the same device of the dosing function and the washing and sterilization function will be noted in a very efficient manner.

Claims (1)

 Claims <B> 1. </ B> Differential volumetric dosing device comprising # a hollow body (1), defining a cylindrical metering chamber (2), at which respectively open a supply line (4) and delivery or ejection (5) of the liquid to be assayed <B>; </ B> # a cylindrical piston (3), whose external diameter D1 corresponds to the clearance, to the internal diameter of the metering chamber (2), and capable of sliding within said chamber, the piston being provided at its periphery with a longitudinal distribution groove (6) capable of coming opposite the opening opening or the supply pipe (4). ) and delivery or ejection (5), characterized in that the dosing chamber (2) is extended at one of its ends by a secondary chamber (7), coaxial with the latter, but internal diameter less than the internal diameter of said metering chamber <B>; < And in that the piston (3) has an extension (10), coaxial with the latter, of external diameter D2 smaller than the external diameter DI of the piston, and corresponding to the clearance, to that of said secondary chamber ( 7); said piston (3) being capable of being driven by an upward and downward translation movement within the hollow body (1), simultaneously or not with a rotational movement. 2. Differential volumetric dosing device according to claim 1, characterized in that the longitudinal distribution groove (6) is located at the periphery of the zone of the piston having the largest diameter D1. . 3. Differential volumetric dosing device according to one of claims 1 and 2, characterized in that the metering chamber (2) is surmounted at its other end by a washing chamber (12), also coaxial with the metering chamber (2), of internal diameter slightly greater than the outer diameter DI of the piston (3), and provided with a perforated inner peripheral wall (14), at which is conveyed by a pipe (16). ) a washing fluid, said pipe (14) being closable, in particular during the metering phases, by means of a valve (17). <B> 4. </ B> Differential volumetric dosing device according to claim 3, characterized in that the perforations (15) formed in the internal partition (14) are distributed over all or part of the height of the washing chamber (12). 5. Differential volumetric dosing device according to one of claims 1 to 4, characterized in that the secondary chamber (7) extending the metering chamber (2) is provided at its lower end with a draining pipe of the washing and sterilizing fluid (8), closable by valve (9), and capable of communicating said chamber with the outside.