FR2949200A1 - DEVICE FOR REALIZING AGITATION OF A LIQUID MEDIUM - Google Patents

Abstract

The invention relates to a movable magnetic element (2) intended to be positioned in the vicinity of the bottom of a container (1) receiving a liquid medium to be agitated, and whose two ends of this mobile magnetic element are each provided with a magnet (13, 14), whose polarity directed towards the bottom of said container is identical. It also relates to a device for stirring a liquid medium using such an element.

Description

The invention relates to the field of agitation of a liquid medium, more particularly in the context of containers of large size, typically greater than 100 liters. BACKGROUND OF THE INVENTION It relates in particular to the agitation of such a liquid medium by rotating an element provided with magnetic properties.

The invention is more particularly applicable in the field of pharmacy, agri-food, chemistry and the nuclear industry.

STATE OF THE ART.

The use of magnetic stirrers is widely known. For example, document FR 2 336 052 describes such a magnetic stirrer. This is basically constituted by a magnetic body of cylindrical general shape, provided with at least one permanent magnet oriented so as to have at least two opposite magnetic poles on either side of its axis of geometric rotation. This magnetic body is subjected to the action of a rotating magnetic field applied from outside the non-magnetic container receiving the liquid medium to be agitated, inducing the rotation of said magnetic body.

Experience shows that the use of such magnetic stirrers is satisfactory for containers of low capacity, typically less than 100 liters depending on the viscosity of the liquid medium to be mixed. On the other hand, when one wishes to proceed with the agitation of large volumes, one encounters several difficulties.

The first difficulty lies in the lack of certainty as to the actual implementation of the agitation. In fact, the tanks in question are generally non-transparent, so that firstly it is not certain that the agitation occurs, notwithstanding the activation of an outer plate generating the rotating magnetic field intended to ensure the rotation of the magnetic bar contained in the tank. In addition, assuming that this agitation has started, it is not certain that it will continue under the expected operational conditions, since it is not uncommon, either because of the large mass of liquid to be agitated or because of its relatively high viscosity 2949200 -2- that the bar or magnetic stirrer picks up the rotary torque to which it is subjected by the plate placed outside the tank and in particular under its bottom and intended to ensure its rotation.

In addition, these tanks of large capacity, generally cylindrical, have a relatively large diameter bottom so that, despite all the care taken in positioning the plate generating the rotating magnetic field, substantially in the center of said tank, the operator is never assured that said platen will actually cooperate with the magnetic bar located in the tank, so that in the negative hypothesis, no agitation occurs.

Finally, there is a need to transport and / or store such tanks. However, with the stirring devices of the prior art, it is not possible to immobilize the mobile element within the vessel, so that its repositioning in operational positioning during the stabilization of the the tank is more random.

The object of the present invention is to provide a device for stirring a liquid medium for high capacity tanks overcoming these various disadvantages.

SUMMARY OF THE INVENTION

For this purpose, the invention firstly aims at a movable magnetic element intended to be positioned near the bottom of a receptacle receiving a liquid medium to be agitated.

According to the invention, the two ends of this movable magnetic element are each provided with a magnet whose polarity directed towards the bottom of the tank is identical.

According to an advantageous characteristic of the invention, the mobile magnetic element intended to be immersed in the container receiving the liquid to be agitated is mounted on a substantially vertical axis mounted free to rotate on a base secured to the bottom of the container, and in particular to the center of said container. In doing so, it eliminates any risk of displacement of said magnetic element relative to the bottom of the container outside the zone where it is deemed to cooperate with the member generating a rotating magnetic field ensuring the effective rotation by magnetic interaction. said movable element, and, as a corollary, the risk of absence of agitation is avoided.

According to this characteristic, the fastening of the base to the bottom of the container is advantageously reversible, this reversibility being obtained in particular by magnetic interaction, said base being provided for this purpose with a permanent magnet 10 cooperating with a permanent magnet of opposite polarity, secured to the bottom of the container and outside thereof substantially in a central position. The permanent magnet reported under the bottom of the container can be either by construction or by gluing.

In doing so, the positioning of the base receiving the axis provided with the rotating magnetic element is substantially centered, thus enabling, as previously said, effective and efficient cooperation of the rotary member with the magnetic element.

The invention also relates to a device capable of agitating a liquid medium contained in a container. This device comprises a magnetic element of the type previously described, in addition to a plate provided with a magnetic rotating member intended to be positioned under said container, and whose rotation ensures that of the magnetic element under the effect of the magnetic field. rotary that it generates.

According to the invention, the rotating magnetic member of the plate comprises two diametrically opposed magnets, whose space separating them corresponds substantially to the space separating the two magnets of the magnetic mobile element, and whose polarity directed towards the container is identical and opposite to that of the magnets of the magnetic element directed towards the bottom of the container. In other words, the invention consists first and foremost in providing two magnetic members intended to interact with each other, respectively a movable magnetic element, immersed in the container receiving the liquid to be agitated, and a rotary member outside said container, and second, to arrange the polarities opposite two to two, contrary to all that was known from the prior art where conventionally, the polarities of each of the magnetic members, respectively of the magnetic element -4- immersed in the tank and of the outer rotating magnetic member of the tank had opposite polarities.

According to an advantageous characteristic of the invention, the rotation of the magnetic rotary member of the plate is provided by an electric motor, provided with sensors able to measure the torque exerted on the rotary member. In doing so, depending on the nature of the liquid medium to be agitated and the speed of rotation, it becomes possible to adjust, and in particular to reduce the speed limit beyond which we must not go to avoid the risk of stalling the magnetic interaction between the rotary member and the magnetic element, and thus ensure a permanent stirring. Moreover, the motor is regulated by means of a variator, able to ensure a progression of the speed of rotation according to any desired type, and consequently a deceleration of said speed.

Finally, the invention also relates to a device for blocking the mobile magnetic element at the bottom of the container which receives the liquid to be agitated, and able to maintain said magnetic element in its operative position during the transport and / or storage phases of said container.

This device consists of two magnets or two sets of magnets, mounted on a support, the distance separating said magnets or said sets of magnets substantially corresponding to the distance separating the two magnets of the magnetic mobile element, the polarity of said magnets. magnets towards the container being opposite to that of the magnets of the movable magnetic element directed toward the bottom of the container.

This support is advantageously mounted on a frame adjustable in height, so as to allow its positioning under and in contact with the outer face of the bottom of the container. BRIEF DESCRIPTION OF THE FIGURES

The way in which the invention can be realized and the advantages which result therefrom will emerge more clearly from the exemplary embodiment which follows, given by way of indication and not by way of limitation, in support of the appended figures. Figure 1 is a schematic representation illustrating the stirring device according to the invention in position relative to a tank receiving a liquid medium to be agitated. Figure 2 is a detail view of the magnetic movable member to be immersed in said vessel. Figure 3 is a view similar to Figure 2 illustrating said element provided with a stirring blade. FIG. 4 is a view from above of the element illustrated in FIG. 3. FIG. 5 is a diagrammatic representation in section, illustrating the locking device of the magnetic mobile element during storage and / or transfer operations. of the receptacle receiving the liquid to be agitated.

DETAILED DESCRIPTION OF THE INVENTION

The magnetic stirring device according to the invention set up in connection with a tank (1) containing a liquid to be agitated is thus schematized in FIG. As can be seen, this vessel has a bottom (3) of relatively large diameter, and partly flat.

According to the invention, the stirring device basically consists of two parts, respectively a magnetic movable element (2) intended to be immersed in the tank (1), and a plate (4) intended for its part to be positioned under said tank as can be seen in Figure 1.

Said magnetic element (2) has been shown in more detail in FIGS. 2, 3 and 4. It basically consists of a rotary shaft (9) rotating about a vertical axis and resting on an axial base (5). ) secured to the inner face of the bottom (3) of said vessel. This solidarity is in this case reversible. It is ensured by the magnetic cooperation between a permanent magnet (6) forming an integral part of the bottom of the base (5) and by another permanent magnet (20), reported under the bottom of the tank for example by gluing. The respective polarities of the magnets (6, 20) are opposed to ensure this magnetic interaction.

Meanwhile, the base (5) rests on the bottom of the tank not only via the magnet (6), but also by pads (8) formed on either side of the magnet (6) pads typically made of polytetrafluoroethylene (TEFLON) to prevent scratching of the bottom of the tank. As a corollary, the rotary shaft (9) is received on the axial base (5) at two separate bearings, upper (10) and lower (11) respectively, advantageously made of PEEK (polyetheretherketone). other terms in a plastic material of low coefficient of friction and resistant to wear. In doing so, the bearings (10, 11) promote free rotation of the shaft (9) about the axis (5).

The shaft (9) extends in the lower part by two arms or radial extensions (12) extending substantially perpendicular to the direction of the shaft (9), and at the end of which, permanent magnets (13) , 14) are mounted. According to a first characteristic of the invention, the permanent magnets (13, 14) have their polarity oriented in the same direction. In this case, their north face is directed towards the bottom of the tank and corollarily their south face is directed in the opposite direction. According to an advantageous characteristic of the invention, the axis (5) receives in the upper part a ring (16), screwable (17), allowing by any suitable means such as a rod, particularly retractable, to go down the element (2) at the bottom of the tank although it is already filled, the precise positioning of the element (2) 20 on the bottom being provided by the cooperation of the magnets (6, 20).

In doing so, the base (5) and the shaft (9) are immersed simultaneously in the tank (1).

The element (2) can receive in addition to the rotary bar constituted by the extensions (12) and the magnets (13, 14), one or more fins (15) having different orientations depending on the stirring effect and the intensity of agitation sought. These fins are better represented in FIGS. 3 and 4.

As a corollary, the underlying plate (4) basically comprises a rotatable member (21), whose rotation is provided by a conventional electric motor and possibly by means of a gearbox.

On this rotary member (21) are mounted two magnets (22, 23), diametrically opposite one another, intended to be positioned substantially perpendicular to the permanent magnets (13, 14) of the magnetic element (2). According to an essential characteristic of the invention, the polarity of the magnets (22, 23) is oriented identically for these two magnets, and exactly opposite that of the permanent magnets (13, 14). In other words and in the example of writing, the south face of the magnets (22, 23) is directed towards the tank, while the north face is directed downwards in FIG.

This particular configuration makes it possible to promote the centering of the magnetic element within the vessel.

According to an advantageous characteristic of the invention, the drive shaft of the plate (4) is provided with sensors adapted to measure the torque exerted on the rotary member (21). By doing so, with appropriate electronics and software, it is possible to determine when the resistive torque becomes too great, and as a corollary the stall limit of the magnetic engagement between the rotary member (21) and the magnetic element. (2) to precisely avoid this risk of stalling and keep agitation in the tank (1).

FIG. 5 shows the locking device, also referred to as the locking hand of the invention. As already indicated, this device is intended to be implemented during the transport and / or storage phases of the container or tank (1). The objective is to impart immobility to the magnetic mobile element (2) immersed in the tank. Moreover, it is also intended to block the magnetic element (2) at the bottom of the tank, in case of fall of the latter.

For this purpose, this device comprises two magnets or two sets of magnets (24, 25), mounted on a support (28). The distance separating these two magnets or these two sets of magnets corresponds substantially to the distance separating the two magnets (13, 14) from the magnetic mobile element (2). This device comes into contact with the outer face of the bottom (3) of the tank (1).

The magnetic intensity is modulated by the implementation of one or more magnets, hence the use of the term series of magnets. This is also true for the magnetic element (2) and the plate (4). The polarity of the magnets (24, 25) in the direction of the tank (1) is opposite to that of the magnets (13, 14) of the movable magnetic element directed toward the bottom of the vessel. In doing so, irrespective of the position of the magnets (13, 14), they are always capable of interacting magnetically with this blocking device thus defined, so that said magnetic mobile element finds itself somehow stuck once. the support (28) mounted near the bottom (3) of the tank (1), preventing any risk of retraction of the shaft (9) from the base (5).

The support (28) is mounted near the bottom (3) of the tank by means of a frame (26) adjustable in height (27).

Due to the blockage thus made, and as already said, there is no longer risk of separation or retraction of the shaft (9) carrying the magnets (13, 14) out of the axis (5). As a corollary, one gets rid of shocks likely to intervene between these two parts. In fact, the bearings (10, 11) of PEEK, or even another equivalent material, carbide or ceramic type are no longer likely to be damaged.

The whole of the interest of the device of the invention is conceived which makes it possible, by means of simple means to realize and to implement, to ensure the stirring of tanks of large capacities, which we did not know. effectively to date, in addition to their transport and storage, without risking inadvertent movement of the magnetic mobile element. 15 25

Claims (9)

REVENDICATIONS1. Mobile magnetic element (2) intended to be positioned in the vicinity of the bottom of a container (1) receiving a liquid medium to be agitated, characterized in that the two ends of this movable magnetic element are each provided with a magnet (13, 14), whose polarity directed towards the bottom of said container is identical. 2. movable magnetic element according to claim 1, characterized in that it comprises a substantially vertical shaft (9) mounted free to rotate on a base (5) secured to the bottom of the container, and in particular in the center of said container, the magnets ( 13, 14) being mounted adjacent the end of radial extensions (12) emanating from said shaft (9). 3. movable magnetic element according to claim 2, characterized in that the fastening is reversible. 4. movable magnetic element according to claim 3, characterized in that the connection of the base (5) to the bottom (3) of the container is obtained by magnetic interaction, said base being provided for this purpose with a permanent magnet (6). cooperating with a permanent magnet (20) of opposite polarity, secured to the bottom of the container and outside thereof. 5. Device for agitating a liquid medium contained in a container (1) comprising a magnetic element according to one of claims 1 to 4, and a plate (4) provided with a magnetic rotating member (21 22 , 23), intended to be positioned under said container, and whose rotation ensures that of the magnetic element (2) under the effect of the rotating magnetic field that it generates, characterized in that the rotating magnetic member (21) , 22, 23) of the plate (4) comprises two diametrically opposed magnets (22, 23), the space between them substantially corresponds to the space between the two magnets (13, 14) of the magnetic element (2 ), and whose polarity directed towards the container is identical and opposite to that of the magnets of the magnetic element directed towards the bottom of the container. 2949200 -10- 6. Device for agitating a liquid medium contained in a container (1) according to claim 5, characterized in that the rotation of the magnetic rotating member (21) of the plate (4) is provided by a electric motor, provided with sensors able to measure the torque exerted on the rotary member (21). 7. Device for agitating a liquid medium contained in a container (1) according to claim 6, characterized in that the plate (4) is provided with a suitable electronic and software, adapted according to measuring the sensors, reducing the rotation speed of the rotary member (21), and thus avoiding the risk of stalling the magnetic interaction between the rotary member and the magnetic element (2). 8. A device for blocking a magnetic stirring element (2) capable of being immersed in a liquid medium which it is desired to carry out stirring, said liquid medium being received within a container (1), in which said magnetic stirring element is according to one of claims 2 to 4, characterized in that it consists of two magnets or two sets of magnets (24, 25), mounted on a support (28), the distance separating the two magnets or series of magnets (24, 25) substantially corresponding to the distance separating the two magnets (13, 14) of the magnetic mobile element (2), the polarity of the magnets (24, 25) towards the container (1) being opposed to that of the magnets (13, 14) of the movable magnetic element directed toward the bottom of the container. 25 9. Device for blocking a magnetic stirring element of a liquid medium in a container (1) according to claim 8, characterized in that the support (28) is mounted on an adjustable frame (26). in height (27), so as to allow its positioning under and in contact with the outer face of the bottom of the container.