Abstract:
The present invention relates to an apparatus for mixing and controlling the temperature of laboratory vessel contents with an accommodating device in detachable connection with an exchangeable block for accommodating and controlling the temperature of laboratory vessels and with a drive by which the accommodating device can be set in a mixing motion, and with a temperature control device with a heat source or sink in heat-conducting connection with the exchangeable block at least through in each case at least one adjoining contact face firstly on the accommodating device and secondly on the exchangeable block, which is characterized in that the detachable connection is maintained by a spring element which, by virtue of its spring force, horizontally clamps together a first undercut between the accommodating device and the exchangeable block in at least one first direction.

Description:
The present invention relates to an apparatus for mixing and controlling the temperature of laboratory vessel contents with an accommodating device in detachable connection with an exchangeable block for accommodating and controlling the temperature of laboratory vessels and with a drive by which the accommodating device can be set in a mixing motion, and with a temperature control device for controlling the temperature of the exchangeable block. 
     BACKGROUND OF THE INVENTION 
     Mixing devices in which vessel contents are admixed are sufficiently well known. In particular for laboratories, there are mixers which can also mix small quantities of liquids by small containers also being put together in suitable holders, so-called “exchangeable blocks” (devices for holding vessels which can also be used for controlling the temperature), in very large groups, being of a two, three or even four-figure number. Such vessels and the associated holders can be standardised in the exchangeable blocks. Thus, there are, for example, vessels with 0.2 ml, 0.5 ml, 1.5 ml and 2.0 mm content—as well as respective exchangeable blocks with suitable holders standardised for that purpose. Further, there are, for example, exchangeable blocks for Cryo vessels, for Falcon tubes (e.g. 1.5 ml and 50 ml), for glass vials and beakers, for containers, for microtitre plates with, for example, 96 and 384 vessels (MTP), for deep well plates (DWP), for slides and for PCR plates with 96 vessels (wells). This list is not inclusive; it does, however, indicate what a large variety of laboratory vessels exist, for which the mixers should be suitable. 
     Because these exchangeable blocks are mostly constructed in such a way that the single vessels are inserted into them from above, a circular translational oscillating mixing motion has become established, by way of preference, for the well-known mixers, which largely proceeds on a horizontal plane. For this purpose, with the well-known mixers an imbalance drive, which is preferably driven by an electric motor, is usually responsible for putting a “table” (an accomodating device, onto which an exchangeable block is fixed) into this circular motion. Usually such mixers are driven with a rotational frequency of 200 rpm to 3,000 rpm, however rotational frequencies of 100 rpm to 10,000 rpm are also possible. The frequency can usually be adjusted. 
     If the mixing device now also has a temperature control device, so that the laboratory vessel contents cannot only be mixed, but also have the temperature controlled, there is an accommodating device in the case of which a source of heat or sink on the temperature control device heats at least one contact surface on the top, and this contact surface has a thermally conductive link to the exchangeable block mounted on it, and in fact by being located directly on its underside. 
     As a rule, the contact surface of the accommodating device and the underside of the exchangeable block, which comes into contact with the contact side, are shaped flat, or virtually flat. In that respect, the gradient of the surface usually deviates from the horizontal plane by a maximum of 10°. The contact surface of the accommodating device can make up the complete surface of the accommodating device, but also only a certain proportion of it, usually at least 70%. 
     In addition, multiple exchangeable blocks can also be attached to an accommodating device, for example 2, 4, 6, 8 or 9. In that regard, the exchangeable blocks preferably have an underside of the same size. In order to produce the thermally conductive contact with the temperature-regulated contact surface of the accommodating device, such exchangeable blocks which usually consist of materials with good thermal conductivity, such as metals, in particular aluminium or silver, wherein the block can be of a solid construction or may have an eroded structure, which, for the purposes of weight reduction, only still has structures for accommodating the sample and good heat transmission from the underside of the exchangeable block to the vessels, are known to be firmly attached to the accommodating device. The screws can be loosened relatively easily with the aid of a tool, such as a screwdriver, so that the exchangeable block can be exchanged, for example, for an exchangeable block for laboratory vessels of a different size. 
     BRIEF SUMMARY OF THE INVENTION 
     The object forming the basis for the present invention is to create a mixing device for mixing and heating contents of vessels that are arranged in an exchangeable block, the handling of which is improved. In particular, it should be possible for the user to attach the exchangeable blocks to the mixing device just using the hand, and also detach them again in the same way. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cropped lateral view through an accommodating device detachably connected to an exchangeable block as a section from a mixing device according to the invention. 
         FIG. 2  shows a partially cropped spatial view of an alternative accommodating device according to the invention, detachably connected to an exchangeable block. 
         FIG. 3  shows a partially cropped spatial view of the configuration from  FIG. 2  from a different perspective. 
         FIG. 4  shows a spatial view of another alternative embodiment of an accommodating device detachably connected to an exchangeable block. 
         FIG. 5  shows a spatial view of a section from  FIG. 4  from a different perspective. 
         FIG. 6  shows a spatial view of an exchangeable block according to the state of the prior art, and 
         FIG. 7  shows a mixing device according to the state of the prior art, without the exchangeable block from  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The mixing device for mixing and controlling the temperature of laboratory vessel contents, according to the invention has an accommodating device with an exchangeable block, a mixing motion drive and a temperature control device. The accommodating device is loosely connected to the exchangeable block, which is set up for accommodating and controlling the temperature of laboratory vessels. The drive is set up to set the accommodating device together with the exchangeable block in a mixing motion. The temperature control device has a source of heat or sink which has a thermally conductive connection to the exchangeable block through contact surfaces, firstly on the accommodating device and, secondly, on the exchangeable block. The contact surfaces are adjacent to one another. 
     The contact surface of the accommodating device and the exchangeable block are preferably shaped flat, or virtually flat. In that respect, the gradient of the surface deviates from the horizontal plane by a maximum of 10°, preferably by 3° at the most, and particularly preferably by 1° at the most. The contact surface of the accommodating device can make up the complete surface of the accommodating device, but also only a certain proportion of it, &gt;70%, preferably &gt;80% or, particularly preferably, &gt;90%. In addition, multiple exchangeable blocks can also be attached to an accommodating device, preferably 2, 4, 6, 8 or 9. In that regard, the exchangeable blocks preferably have an underside of the same size. 
     According to the invention, the detachable connection of the accommodating device to the exchangeable block is held by a spring element, which, through its spring tension, tightens a first undercut into one another horizontally in at least one direction. In this respect, the undercut exists between the accommodating device and the exchangeable block. The undercut is preferably located on the side of the exchangeable block which is opposite the side where the spring element grips. The invention advantageously enables a secure, form-fit connection between the exchangeable block and the accommodating device, even if the latter is exposed to the stresses of the previously mentioned mixing motions. The connection can, firstly, be produced and detached again in a way that is easily manageable, and, secondly, is free of clearance due to the spring pre-load. In particular, the exchangeable block can be connected and detached by the user, just using the hand. 
     The spring tension applied by the used spring element usually amounts to 30 to 150 N, preferably 50 to 100 N, and, by way of especial preference, 65 to 85 N. As a result, firstly a secure connection between the accommodating device and the exchangeable block is ensured, and, secondly, the tension is only so great that it can also be applied by a user. 
     To fasten the exchangeable block to the accommodating device securely, it needs to be fixed in both horizontal dimensions (the X and Y directions) and also in the vertical direction (the Z direction). The connection according to the invention ensures a form-fit connection in the Z direction, at least through the first undercut. In at least one first direction (for example X or Y), through its spring tension the spring element tightens the one of the two mould parts undercutting one another into the other, and in this way establishes the connection in this horizontal direction. In this respect, the one mould part is located on the accommodating device, and the other mould part, belonging to it, on the exchangeable block. Preferably, the undercutting mould part undercutting the other one is placed underneath the exchangeable block. The spring tension of the spring element likewise preferably grips underneath the exchangeable block. 
     By preferably clamping together the two mould parts undercutting one another, also of a second undercut in a second horizontal direction (which is linearly independent of the first horizontal direction), the connection is set against any horizontal movement completely, and in fact, advantageously, free of play. The clamping together also in the second horizontal direction can either be effected through the spring tension of a second spring element or also through the spring tension of the first spring element. In the latter case, the spring element may be designed in such a way that its spring tension has such an impact upon the mould parts that it is broken down, vectorially, into one component acting in the first horizontal direction and one component acting in the second horizontal direction. 
     Preferably, for one horizontal direction or for both directions in which the spring tensions work horizontally, two spring tensions are provided, so that the forces clamping the exchangeable block are distributed over these spring elements. This makes it considerably easier for the user to operate and detach the spring elements. Accordingly, still further spring elements can also naturally be provided, for one or both horizontal directions. Too great a number of spring elements that need to be operated do, however, in turn, make it troublesome to attach and detach the exchangeable block. 
     It may also be advantageous not to provide for an undercut in the second horizontal direction, but rather a horizontal stopper, such as a centering pin. Then the connection from the first undercut and said at least one spring element, that works in a horizontal direction, can be made by a bent hook into the undercut, and subsequently folding down the block. 
     Further advantages and features of the device according to the invention are described with reference to the attached figures, which represent the embodiments of the mixing device in accordance with the invention. 
     In  FIG. 1 , an accommodating device  2 , which can be put into a horizontal mixing motion by a drive, not shown, is illustrated. Further, the mixing device (not completely shown in its entirety) has a temperature control device (only partially shown) with a heat source (not shown), which can heat the accommodating device  2 . The accommodating device has a thermally conductive connection with an exchangeable block  4 , which is mounted on the accommodating device  2 . The thermally conductive connection is made through largely horizontal contact surfaces  6 ,  8  lying on top of one another, and in fact, firstly  6 , on the top of the accommodating device  2 , and, secondly,  8 , on the underside of the exchangeable block  4 . 
     The accommodating device and the exchangeable block are detachably connected with one another through a spring element  10 , namely a lateral pressure component  10 . Lateral pressure components are known construction elements, which have a head  12 , which can be moved laterally, on a spring, around a pivotal point  14 , in any desired direction. Through its spring tension, the lateral pressure component  10  tautens a first undercut  16 —namely an inclined plane  16 , as a form-fit active surface of the one  18  of the mould parts  18 ,  20  undercutting into one another on the exchangeable block  4 —into the other  20  of the mould parts undercutting one another, in a first horizontal direction (in the figure towards the left), namely an inclined plane  16 , as a form-fit active surface on the accommodating device  2 . 
     The inclined planes  16  on the two mould parts  18  and  20  are orientated in such a way that the tensioning in of the exchangeable block by means of the lateral pressure component  10 ,  12  (in the figure towards the left) transforms the pre-stress force working towards the left on the inclined plane  16  of the form-fit active surface of the mould part  20  of the accommodating device  18  into a reaction force, which has a vertical force. This vertical force has the effect of a clamping force on the horizontally adjacent contact surfaces  6 ,  8 , and thus advantageously brings about a secure thermally conductive connection between the contact surfaces  6 ,  8 . 
     Not separately illustrated is a vertical section through the accommodating device and the exchangeable block (in top view) to the section in the figure. The fixing in this second horizontal device is simply formed by lateral vertical delimitation cheeks formed on the accommodating device, between which the exchangeable block is guided in a form-fit manner. 
     In a vertical direction (the Z direction), the detachable connection is, on the one hand, secured by the undercut  16  described and, on the other hand, by the lateral pressure component. 
     To release the detachable connection between the exchangeable block and the accommodating device, the contact surfaces  6 ,  8  lying horizontally adjacent to one another can be pressed apart from one another using a lever device  22 . As a result the head  12  of the lateral pressure component  10  is pressed to the side along initial conductive surfaces  24  on the exchangeable block  4  (in the figure towards the right) and finally snaps out from the furcation  26  in the exchangeable block, into which, when the connection was closed (horizontally adjacent contact surfaces  6 ,  8 ), it had been inserted. 
     Alternatively, the connection between the exchangeable block and the accommodating device could be released by a lever (not shown) directly gripping the head  12  of the lateral pressure component  10 , and its pivoting in such a way (in the figure towards the right) that the clamping together of the mould parts  16 ,  18  is released. 
     A further alternative (likewise not shown) for detaching the connection can be formed by the accommodating device mould part  20  being able to be moved laterally (in the figure towards the left) out of the undercut  20  using a suitable lever (not shown). 
     The detachable connection illustrated can be detached and, once detached easily produced again by the exchangeable block  4  with its undercut mould part  10  (as well as any second undercut mould part not illustrated, already mentioned above) being inserted into the complementary undercut mould part  20  of the accommodating device  2 , wherein which the lateral pressure component  12  (as well as any second lateral pressure component mentioned above) rests on the edges of the respectively associated furcation  26  in the exchangeable block allocated. Second conductive surfaces  28  on the heads  12  of the lateral pressure components are orientated in such a way that they allow the detachable connection from this previous position (not shown) to be snapped into place by pressing vertically on the contact surfaces that are horizontally adjacent to one another, by the heads  12  of the lateral pressure components  10  then sliding through the furcation  26  and snapping into place. 
     In  FIGS. 2 and 3 , a device is shown in a spatial view (partially cut off) which is very similar to  FIG. 1  (functionally comparable elements have the same reference numbers as in  FIG. 1 ): also in  FIGS. 2 and 3 , the detachable connection between the exchangeable block  4  and the accommodating device  2  is formed by a lateral pressure component  10  as a spring element, which, with its lateral (horizontal) spring tension, locks the components of a first undercut in the form of an inclined plane  16  into one another, In contrast to  FIG. 1 , the lateral pressure component  10  in  FIGS. 2 and 3  is, however, attached to the exchangeable block  4  and the furcation  26  (as an active surface complementary to the head  12  of the lateral pressure component  10 ) on the accommodating device  2  (and not vice versa, as in  FIG. 1 ). The remainder of the description of  FIG. 1  can also be read identically to that of  FIGS. 2 and 3 . 
     The detachable connection according to  FIGS. 4 and 5  differs to a greater extent from the two embodiments described so far (also in this case, functionally comparable elements are, however, designated with the same reference number as in  FIGS. 1 to 3 , even if they have a different shape): more schematically, the accommodating device  2  is indicated by a base plate which has two cones  23  sticking out in a perpendicular manner along its one edge  3 , which have a circumferential groove  26  just underneath their upper end. Once the exchangeable block  4  has been placed on the accommodating device  2  from above in such a manner that the horizontal contact surfaces  6 ,  8  of the accommodating device  2  and the exchangeable block  4  are adjacent to one another ( FIG. 5 ), a form fit is achieved by a spring wire  10  being pressed laterally into the latter. In this position, the two cones  23  extend through borings  25  on the exchangeable block  4 , stick out on top of the borings  25 , so that the grooves  26  are exactly flush with the lower edge of the borings  25 —and, pressed into there through its elastic force, the spring wire  10  grasps the grooves  26  laterally. 
     Through this lateral pre-stressing, the undercut, which is formed, firstly, by the upper edge  16  of the grooves  26 , and, secondly, by the top of the spring wire  10 , is interlocked horizontally. 
     Along the edge  30 , which is located opposite the edge  3 , the accommodating device  2  and the exchangeable block  4  have pre-positionable connecting elements  32  which are a form fit, which likewise ensure, through an undercut, as well as lateral stops, that the exchangeable block  4  and the accommodating device  2 , do not move away from one another vertically (due to the undercut in the elements  32 ) or shift horizontally (in the direction of the edges  3 ,  30 ) (due to the lateral stops in the elements  32 ). The remaining degrees of freedom are laid down based on the form-fit connection between the cones  23  and the borings  25 , as well as based on the undercut between the spring wire  10  and the grooves  26 . 
     This detachable connection between the accommodating device  2  and the exchangeable block  4  can be detached by a push button  22 , which presses the spring wire  10  out from the grooves. 
     In regard to  FIGS. 6 and 7 , merely by way of illustration, an exchangeable block  40  ( FIG. 6 ) designed according to the state of the prior art is shown, which can be detachably attached, by means of two screws  42  and two threaded holes  44 , to an accommodating device  46  of a mixing device  48  designed according to the state of the prior art.