Agitating – By movement of support for removable mixing chamber
Reexamination Certificate
1999-12-10
2001-12-25
Drodge, Joseph W. (Department: 1723)
Agitating
By movement of support for removable mixing chamber
C366S213000, C366S214000, C366S232000, C366S220000, C366S144000
Reexamination Certificate
active
06332705
ABSTRACT:
RELATED APPLICATIONS
This application is the U.S. National Phase of International Application No. PCT/EP98/01303 filed on Mar. 6, 1998, which claims priority to German Application Nos. 197 09 237.3 filed Mar. 6, 1997, 197 09 236.5 filed Mar. 6, 1997, and to 197 24 046.1 filed Jun. 7, 1997, the entire teachings of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
Devices for stirring liquids are generally known, in which the surface of an appliance base containing a magnetic-field generating system has placed on it a stirring vessel, in which the liquid to be treated is introduced and a magnetic stirring rod is inserted, which interacts with a rotating magnetic driving field generated by the magnetic-field generating system of the appliance base and which stirs the liquid.
In specific instances of use, it may be expedient to avoid the difficulties arising as a result of the separate handling of the stirring rod and the wetting of the latter by the liquid to be treated.
German Utility Model G9406540.4 discloses a magnetic stirring device which, in a plate-shaped base, contains a number of magnetic-field generating systems which generate rotating magnetic fields near the top side of the base. Located on the top side of the base are rotatably mounted vessels, for example in the form of test tubes, which have, near their lower end, a holder containing a magnetic member, the said holder being supported in each case with a bearing pivot point against a step bearing on the top side of the base. The vessels are rotatably mounted near their upper end on a carrier, in such a way that the vessels can be set in rotation by means of the magnetic members which interact with the magnetic rotary fields. If the vessels are driven at a changing rotational speed or in the direction of rotation which, for example, changes periodically, liquid introduced into the vessels undergoes intimate intermixing due to the shearing forces acting in it, since liquid located in the treatment vessel is entrained in the layers adhering to the vessel inner wall, whereas the parts of the liquid volume which are near the axis lag behind during rotation.
It is apparent that the pivot point mounting of the lower vessel end of the holder attached onto the lower vessel end in a bearing depression ensures that a vessel runs centrically in its lower part within a wide rotational speed range, but that the rotary mounting near the upper vessel end tends to run unevenly because of the comparatively large diameter of the vessel, and that undesirable rattling phenomena occur which may ultimately cause the vessel to stop if the driving torque of the magnetic-field generating system is no longer sufficient. A reduction in the bearing play of the upper rotary mounting presents difficulties on account of the tolerances in the diameter of the vessels and may put at risk the smooth movement of the rotary mounting of the vessel as a whole. Undesirable rattling phenomena of the upper rotary mounting are triggered by small unbalances [lacuna] is pressed against a point region of the bearing bore by the centrifugal forces against the vessel outer wall, and the vessel begins to roll on the bearing-bore inner wall under the driving force.
OBJECT OF THE INVENTION
Accordingly, the object of the invention is to design a stirring device in such a way that the vessel experiences smooth vibration-free running within a wide rotational speed range and maintains this property also within a wide range of height of the centre of gravity relative to the vessel. In a further development, the vessel rotational speed range is to be extended beyond 8,000 l/min.
SUMMARY OF THE INVENTION
In a particular refinement of the stirring device, the coupling between the rotating magnetic driving fields generated by the magnetic-field generating system of the drive means and the driving-part arrangement provided in the holding extension of the treatment vessels is improved, and, consequently, not only is the efficiency of the drive increased, but, at the same time, a reliable and low-vibration rotary mounting for operation within a wide rotational speed range also becomes possible.
It may be pointed out, here, that individual features of the embodiments described may, within the scope of the invention, even though not expressly mentioned here, be combined with one another according to the knowledge of the person skilled in the art, and therefore the invention also embraces such combinations.
It should be mentioned, further, that the drawings sometimes show only a single vessel for receiving the liquid to be treated, the said vessel being elongated along an essentially vertical axis of symmetry and having an upper filling orifice, but that, as is known per se, all the embodiments contain a plurality of such vessels capable of being operated parallel to one another and of associated magnetic-field generating systems.
In stirring devices specified here, the rotary mounting means provided near the upper end of the vessel have considerable clearance relative to the vessel outer wall, in such a way that the vessels can easily be inserted into the stirring device or extracted from it again, and this may be carried out automatically by means of a manipulator or robot. Despite this large bearing play, the centring and stabilizing means bring about reliable damping of vibrations and rattling phenomena during the running of the vessels within a wide rotational speed range and also in cases where the centre of gravity of the vessel and filling is relatively high.
REFERENCES:
patent: 3627276 (1971-12-01), Gilford
patent: 4345843 (1982-08-01), Berglund et al.
patent: 4390283 (1983-06-01), Meyer
patent: 5195825 (1993-03-01), Ringrose
patent: 5399013 (1995-03-01), Sawyer
patent: 94 06 450.4 (1994-09-01), None
patent: 297 09 966 (1997-08-01), None
patent: 0 035 762 (1981-09-01), None
Herz Helmut
Kaufmann Klaus
Cecil Terry K.
Drodge Joseph W.
Hamilton Brook Smith & Reynolds P.C.
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