EP1023936A1 - Magnetic drive agitator and method for adjusting the torque for force transmission of a such agitator - Google Patents

Abstract

The rotor can be moved in translation parallel to the X-X' axis inside the sleeve between a first position where the two means of coupling are matching to drive the helix in rotation and a second position where they do not interact or interact little, so the helix can be displaced relative to the sleeve without the two couplings interacting The agitator comprises a union (5) which can be mounted in a sealed fashion in a wall (2a) of a receiver with a blind sleeve (10) inside which is fitted a rotor (20) supporting a first magnetic coupling (21). A helix (8) placed around the sleeve is equipped with a second magnetic coupling (17) to drive the helix around an axis (X-X') of rotation. The rotor can be moved in rotation around and parallel to the axis X-X' by a drive shaft (22) which is itself movable in rotation around and parallel to the X-X' axis between two positions corresponding to those of the rotor. The rotor has a central hollow to receive a screw for mounting the rotor on the shaft, with the screw placed along the X-X' axis. The rotor and/or shaft can be immobilized during their parallel movement in an intermediate position. The drive shaft is mounted to slide inside a hollow shaft which is the output from a reduction gear, with the two shafts fixed together in rotation. The hollow shaft has a screw which acts with a fillet fixed to the drive shaft. The parallel movement is controlled by a hydraulic or pneumatic jack. Process of controlling couple transmitted to a magnetic agitator as described above by controlling the position of the rotor along the X-X' axis.

Description

The invention relates to a stirrer with magnetic drive and a method for adjusting the transmission limit torque effort of such an agitator.

Agitators are conventionally used for brewing a mixture located inside a container to avoid decantation or any other alteration of the mixture during time. The advantage of a stirrer with magnetic drive that the setting in motion of the propeller which it comprises is realized by a magnetic coupling which takes place without contact physics between two rotating parts, one of which is driven by the output shaft of an electric motor while the other consists of a propeller. This allows the part associated with the electric motor shaft outside the container while the propeller is installed inside the container. Any danger of leakage from the agitator can thus be dismissed. This is particularly useful when the mixture is toxic or when pollution of it by external agents should be avoided as, for example, in the case of a drug composition.

The magnetic coupling used for an industrial stirrer must be intense in order to train the agitator propeller with sufficient force. However, it is sometimes necessary method of disassembling the propeller, in particular for reasons maintenance or inspection of the container in which is formed the mixture. It is thus common to plan to clean the propeller of an agitator and / or sterilize it outside the container at the end of each manufacturing batch. He's sometimes necessary to dismantle the propeller to proceed with the exchange standard of wearing parts such as bearings. When a propeller has been dismantled, it must be replaced with the greater precautions on its support, avoiding the most possible impacts that could damage the blades, bearings and / or the surface of the container.

The magnetic forces necessary for the drive of the propeller of an industrial agitator are such that the effort that must exercise an operator to remove the propeller is very important, because this effort must overcome both the weight of the helix and the magnetic coupling force required to training. This is even more critical when handing over in place of the propeller, insofar as, during the presentation of it, it happens that the magnetic force is so intense that the propeller escapes the operator and comes to tackle violently against its support, which has the consequence damage the bearings, or even injure the operator.

In addition, it is particularly delicate for an operator to present the propeller perfectly aligned with the axis of rotation of its rotor, so that if it escapes the operator because of the magnetic force which it undergoes, it tends to be biased on its support, which can lead to the destruction of one of its blades, to the marking of the internal surface of the tank and / or damage to one of the bearings. To overcome this drawback, we can consider systematically disassemble the propeller drive assembly located outside the container, i.e. its motor drive and possibly the reduction gear which is its associated, in order to remove the magnetic forces exerted on the propeller during assembly or disassembly. Such a approach requires manipulation by a parts operator heavy and bulky, these parts being generally located under tanks or containers that are difficult to manufacture and access. In addition, such disassembly of these drive systems must be followed by a reassembly during which the axes of the rotating parts must be very precisely aligned, which is not always possible given the difficulties of access to the reassembly areas of the engine and its possible reduction gear. In addition, the disassembly of the external part of the agitator is to expose the drive rotor to the air magnetic, this rotor being provided with permanent magnets whose external surfaces may be covered with magnetic impurities. Given the small clearance present around the rotor, these impurities can lead to magnet processing and blockage of the agitator.

It is to these disadvantages that we hear more particularly remedy the invention by proposing a drive agitator magnetic whose propeller can be easily disassembled and put back in place, without risk that the magnetic forces it undergoes do not interfere with these operations and without requiring the complete disassembly of the agitator part outside the container on which it is mounted.

In this spirit, the invention relates to a stirrer with magnetic drive which includes a flange adapted to be tightly mounted in a wall of a container and provided with a blind sleeve inside which is housed a rotor supporting a first magnetic coupling means, then that a propeller arranged around this sleeve is equipped with a second magnetic coupling means for driving this helix around an axis of rotation. This agitator is characterized in that the rotor is movable in translation, parallel to this axis inside the sleeve, between a first position where the first and second coupling means are next to each other, so that they cooperate for training in rotation of this propeller, and a second position where they interact little or no, so that this propeller can be moved relative to the sleeve without interaction notable first and second coupling means.

Thanks to the movable nature of the rotor in translation, it can be retracted during assembly and disassembly of the propeller, so that the coupling means magnetic that it supports, such as permanent magnets, is removed from the coupling means which equip the propeller with a sufficient distance to prevent the magnetic force between these coupling means does not disturb the mounting or the disassembly of the propeller. The displacement of the rotor inside the sleeve takes place in a direction corresponding to shear the air gap between the magnetic coupling means, that is to say in practice between the permanent magnets respectively associated with the rotor and the propeller. This shear perpendicular to the magnetic force created between these magnets does not require significant effort as far where this magnetic force does not oppose this shearing. In in other words, the magnetic coupling between the magnets of the rotor and propeller is annihilated without this magnetic coupling strongly opposes the translation of the rotor. When mounting or reassembling the propeller, simply place it on the sleeve, then move the rotor in translation inside the sleeve until the magnets he wears are at or near the magnets worn by the propeller. The invention therefore makes it possible to set up the propeller without interference with the magnets of the rotor, then move it until it can drive the propeller, this displacement being carried out in a direction such that it it is not necessary to overcome an intense magnetic effort.

According to a first advantageous aspect of the invention, the rotor is moved in rotation around its axis and in translation parallel to this axis, by a drive shaft itself mobile in rotation around this axis and in translation parallel to this axis, between two positions corresponding to first and second rotor positions. We can predict that the rotor is provided with a central recess for receiving a screw for mounting the rotor on the shaft, this screw being arranged substantially along the aforementioned axis.

According to another advantageous aspect of the invention, the rotor and / or the drive shaft are able to be immobilized, in their translational movement parallel to the axis above, in an intermediate position between the first and second positions. This aspect of the invention makes it possible to envisage to use the agitator while the magnetic coupling effort between the rotor and the propeller is decreased compared to the position where the respective coupling means are opposite, so that the drive torque of the propeller is limited. This is advantageous when you want to use the agitator with a mixture whose viscosity is variable, for example made of a chemical reaction. In this case, the agitator is blocked when the viscosity of the mixture is such that the torque that can be transmitted to the propeller is less than that which would be necessary to set it in motion in this mixture.

According to another advantageous aspect of the invention, the tree drive is slidably mounted inside a shaft output hollow of a reducer, these drive shafts and hollow shaft being integral in rotation. By reducer, we hears any device for transmitting a movement of rotation, whatever its reduction ratio. He can particular be a 1/1 ratio angle gear. We can provide that the hollow shaft carries a nut whose internal thread is able to cooperate with an external thread of a threaded rod integral with the drive shaft. This creates a system, with nut and worm, for adjusting the position in translation of the drive shaft and the rotor. The rod threaded is advantageously provided, at one of its ends protruding outside the hollow shaft, means control of its rotation around its axis. In this case, a protective cover for this end of the threaded rod and these control means can be provided, this cover being mounted removable on the reducer.

According to an alternative embodiment of the invention, the rotor can be controlled in translation along the above axis by a pneumatic or hydraulic cylinder.

The invention also relates to a method for adjusting the force transmission torque limit of an agitator such as previously described, which consists in adjusting the position of the rotor along this axis, so that the first and second magnetic coupling means are more or less opposite. Thanks to the process of the invention, the transmissible torque between the rotor and the propeller is more or less important, as indicated above.

• la figure 1 est une représentation schématique de principe d'un récipient pour mélange équipé d'un agitateur conforme à l'invention ;
• la figure 2 est une vue à plus grande échelle du détail II à la figure 1, l'agitateur étant représenté en coupe, dans une première position ;
• la figure 3 est une vue analogue à la figure 2, alors que l'agitateur est dans une seconde position et
• la figure 4 est une vue partielle de la partie inférieure d'un agitateur conforme à un second mode de réalisation de l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of two embodiments of a stirrer with magnetic drive conforming to its principle and of their adjustment method, given only by way of example and made with reference to the appended drawings in which:

• Figure 1 is a schematic representation of the principle of a mixing container equipped with an agitator according to the invention;
• Figure 2 is an enlarged view of detail II in Figure 1, the agitator being shown in section, in a first position;
• FIG. 3 is a view similar to FIG. 2, while the agitator is in a second position and
• Figure 4 is a partial view of the lower part of an agitator according to a second embodiment of the invention.

In FIG. 1, a container 1 is formed from a tank 2 in which is arranged a mixture 3, while a cover 4 is designed to close an upper opening of the tank.

In the bottom wall 2 a of the tank 2 is disposed a flange 5 of non-magnetic material supporting a reduction gear 6 and an electric motor 7, located outside the tank 2. A propeller 8 is disposed inside the tank 2, in the mixture 3. The rotation of the propeller 8 by the motor 7 results in a displacement of its blades 8 a , two of which are visible in the figures, around an axis of rotation XX ' , which has the effect of mixing the mixture 3.

The flange 5 forms a blind sleeve 10 which extends inside the tank 2. A bearing 11 is mounted on the end 10 a of the sleeve 10 by means of an axis 12 whose threaded end 12 a is received in a tapping 10 b of the end 10 a of the sleeve 10. The bearing 11 supports a bush 13 whose outer surface 13 a constitutes a bearing surface. The propeller 8 comprises a head 14 formed of a ring 15 whose internal circular surface 15 a is intended to fit around the surface 13 a of the sleeve 13. A smooth bearing is thus produced by contact, for example metal -metal, between surfaces 13 a and 15 a .

Three branches, two of which are visible in the figures with the reference 15b , and which are regularly distributed around the periphery of the ring 15, extend outwards from the latter and support a sheath 16 disposed around the blind sleeve 10. the blades 8a of the impeller 8 are welded to the outside of the sheath 16. This sheath 16 carries on its inner surface 16a facing the sleeve 10, two rows of permanent magnets 17 whose polarity north-south is directed in directions AA 'and BB' generally perpendicular to the axis X-X '.

A rotor 20 is disposed inside the sleeve 10 and comprises a first sleeve-shaped part 20 a on the external surface 20 b of which are mounted permanent magnets 21 aligned with the magnets 17, in the configuration of FIG. 2 In this configuration, the directions CC ′ and DD ′ of polarity of the magnets 21 are substantially aligned with the directions AA ′ and B-B ′. The rotor 20 is provided to rotate around the axis XX 'and cause, thanks to the magnetic coupling produced between the magnets 21 and 17, the propeller 8 in rotation about this axis.

The rotor 20 is made integral with a drive shaft 22 by means of a screw 23 disposed in the central recess 20 c of the sleeve 20 a along the axis XX 'and penetrating into an end thread 22 a of l 'shaft 22. The rotor 20 is provided with an axial bore 20 d for receiving the end 22 b of the shaft 22 in which is formed the thread 22 a . A screw 24 is disposed in a radial bore in the part of the rotor 20 in which the bore 20 d is formed, so as to come into abutment against the external radial surface of the end 22b of the shaft 22, so as to immobilize elements 20 and 22 in rotation.

The flange 5 is integral with a spacer 25 on which is mounted the reducer 6. The spacer 25 defines a housing cylindrical 26 for receiving the shaft 22.

An output shaft 27 of the reduction gear 6 is driven by pinions 28 and 29, the pinion 29 being engaged, thanks to a shaft 30, with the output shaft 31 of the motor 7. The shaft 27 is hollow and defines a internal volume in which the shaft 22 can slide, the shafts 22 and 27 being integral in rotation by means of a key 32. Thus, the shaft 22 can slide inside the shaft 27 and be driven in rotation by that -this, thanks to the key 32. Note 27 has a longitudinal groove in the shaft 27 in which the key 32 can slide.

The end 22 c of the shaft 22 opposite the rotor 20 is integral with a threaded rod 33, a first end 33 a is provided for entering a housing 22 d of the end 22 c . Two screws 34 serve to axially immobilize the end 33 a of the rod 33 inside the housing 22 d .

The second end 33 b of the rod 33 cooperates with a nut 35 fixed to the end of the shaft 27 opposite the spacer 25. A nut 36 is immobilized on the end 32 b of the rod 33 by means of a pin 37. It is thus possible to rotate the threaded rod 33 inside the nut 35 thanks to the nut 36. A screw-nut system has thus been formed which, due to the fixed position in translation of the nut 35 relative to the axis XX ′, makes it possible to control the displacement in translation of the rod 33, of the shaft 22 and of the rotor 20 between the two positions respectively shown in FIGS. 2 and 3. L 'nut 36 therefore constitutes a means of controlling the movement of these elements along the axis X-X'.

A cover 38 is mounted on the reduction gear 6 around the end 33 b of the threaded rod 33 in order to protect the elements 35 to 37. The cover 38, made of metal or plastic, can be screwed or clipped onto the reduction gear 6.

The operation is as follows:

From the position of FIG. 2, and when it is necessary to disassemble the propeller 8, the cover 38 is removed and the nut 36 is operated with a wrench in a direction of unscrewing of the rod 33 relative to the nut 35, so that this rod is gradually extracted outside the tube 27, which has the consequence of driving the shaft 22 in the direction of the nut 35 to the position shown in the figure 3. in this position, the magnets 17 and 21 are no longer opposite each other, since the socket 20 a of the rotor 20 is received in a portion of the inner volume of the sleeve 10 located outside of the tank 2. in this position, the directions of polarity CC 'and DD' of the magnets 21 are offset with respect to the directions of polarity AA and BB 'of the magnets 17 by a distance d such that the magnetic coupling force between these magnets is practically zero. In other words, there is then no significant magnetic interaction between the magnets 17 and 21. The propeller 8 can therefore be removed, without the magnetic forces exerted between the magnets 17 and 21 being opposed to it. in a sensitive way.

At the end of cleaning and / or maintenance operations, propeller 8 can be replaced without exerting on the magnets 17 too great an attraction force due to the magnets 21.

It is then possible to operate the nut 36 in the opposite direction to that mentioned above, so that the threaded rod 33 again penetrates inside the tube 27 and that the rotor 20 is pushed by the shaft 22 to the position of FIG. 2 in which the magnets 17 and 21 are again next.

The displacement of the magnets 21 relative to the magnets 17 takes place perpendicular to the magnetic attraction forces which are exerted between these magnetic coupling elements, so these efforts should not be defeated while they can be particularly important if the air gap between the magnets is reduced. We are working here in shearing of these forces and maneuvering of the rotor 20 between the positions of the Figures 2 and 3 is relatively easy. In addition, a reduction important can be obtained according to the pitch of the thread of rod 33 and nut 35.

When the rotor 20 is raised inside the sleeve 10, it is possible to interrupt the rotation of the rod threaded 33 in an intermediate position between those of Figures 2 and 3, only a fraction of the magnets 21 reaching at the magnets 17 closest to the bottom of the tank 2. Under these conditions, the maximum torque that can be transmitted between the rotor 20 and the sheath 16 of the propeller 8 is less important that in the position of figure 2, which turns out useful when you want to limit the torque that can be transmitted to the propeller 8, in particular in the case of a mixture 3, the viscosity changes over time, for example due to of a chemical reaction modifying this viscosity. It is so possible to avoid agitation of the mixture at the end of a chemical reaction, i.e. when this viscosity has reaches a predetermined value. The maximum torque value transmissible depends on the proportion of magnets 17 and 21 which are facing each other and create a magnetic coupling effort partial. It is possible to calibrate the agitator of the invention to determine the maximum transmissible torque as a function of the position of rotor 20. After this calibration, you can scale the rod 33, which allows a user to move it towards inside the tube 27 as a function of the limit or maximum torque wish.

A device (not shown) for detecting movement propeller size 8 can be combined with the agitator the invention so that the operator is notified when the propeller 8 no longer turns while the motor 6 is running, such situation corresponding to a predetermined viscosity value for mixing 3. The engine 7 can be stopped in These conditions.

When the rotor is positioned in its drive position propeller 8, whether it's the position of the Figure 2 or an intermediate position, the cover 38 is reassembled on the reducer 6.

In the embodiment of the invention shown in Figure 4, elements similar to those of the embodiment Figures 1 to 3 bear identical references. The agitator of this second embodiment differs from the previous one essentially in that the end 33b of a rod 33 ', which is not threaded, is integral with a piston 50 movable in translation along the axis XX ′ inside a cylinder 51, the elements 50 and 51 belonging to a pneumatic cylinder 52 supplied with air through two conduits 53 and 54. Depending on the pressures prevailing in the rooms defined at inside the cylinder 51 on either side of the piston 50, the rod 33 is moved along the axis XX ′, which makes it possible to move the magnets 21 of the rotor 20 relative to the magnets 17 sheath 16, as in the first embodiment.

Of course, the cylinder 52 could also be a cylinder hydraulic.

The use of a jack allows rapid maneuvering of the rotor 20 inside the sleeve 10, such an operation can be automated.

Other systems for controlling the movement of the rotor 20 inside the sleeve 10 can be envisaged, in particular a spring or cam system.

In all cases, the process for adjusting the limit torque transmission of force described above remains applicable.

Claims (10)

Agitator with magnetic drive, said agitator comprising a flange (5) capable of being mounted in a sealed manner in a wall (2 a ) of a container (1) and provided with a blind sleeve (10) inside which is housed a rotor (20) supporting a first magnetic coupling means (21), while a propeller (8) disposed around said sleeve is equipped with a second magnetic coupling means (17) for driving said propeller around an axis (X-X ') of rotation, characterized in that said rotor (20) is movable in translation, parallel to said axis (X-X'), inside said sleeve (10), between a first position where said first and second coupling means (17, 21) are substantially opposite (A-A ', B-B', C-C ', D-D'), so that they cooperate for the rotational drive of said propeller (8), and a second position where they do not interact or little, so that said propeller (8) can be moved relative to the said sleeve (10) without significant interaction of said first and second coupling means (17, 21). Agitator according to claim 1, characterized in that said rotor (20) is moved, in rotation about said axis (X-X ') and in translation parallel to said axis, by a shaft drive (22) itself mobile, rotating around said axis and in translation parallel to said axis, between two positions corresponding to said first and second positions of said rotor. Agitator according to claim 1, characterized in that said rotor (20) is provided with a central recess (20 c ) for receiving a screw (23) for mounting said rotor on said shaft (22), said screw being disposed substantially along said axis (X-X '). Agitator according to one of claims 1 to 3, characterized in that said rotor (20) and / or said shaft (22) are able to be immobilized, in their translational movement parallel to said axis (X-X '), in an intermediate position between said first and second positions. Agitator according to one of claims 2 to 4, characterized in that said drive shaft (22) is mounted sliding inside a hollow output shaft (27) of a reducer (6), said drive shafts and the hollow shaft being integral in rotation (32). Agitator according to claim 5, characterized in that that said hollow shaft (27) carries a nut (35) able to cooperate with a threaded rod (33) integral with said drive shaft (22). Agitator according to claim 6, characterized in that said threaded rod (33) is provided, at one (33 b ) of its ends projecting outside of said hollow shaft (27), with control means (36, 37) of its rotation about said axis (X-X '). Agitator according to claim 7, characterized in that it comprises a cover (38) for protecting said end (33 b ) of said threaded rod (33) and said control means (36, 37), said cover being mounted removably on said reducer (6). Agitator according to one of claims 1 to 5, characterized in that said rotor (20) is controlled in translation along said axis by a pneumatic or hydraulic cylinder (52). Method for adjusting the force transmission limit torque of a stirrer with magnetic drive supported by a flange (5), sealingly mounted in a wall (2 a ) of a container (1) and provided with a sleeve blind (10) inside which is housed a rotor (20) supporting a first magnetic coupling means (21), while a propeller (8) disposed around said sleeve is equipped with a second magnetic coupling means ( 17) for driving said propeller around an axis of rotation (X-X '), characterized in that it consists in adjusting the position of said rotor along said axis (X-X') so that said first and second magnetic coupling means (17, 21) are more or less opposite.

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