Abstract:
The present invention relates to a lid for closing a centrifuge rotor, characterized by a form-fitting, rotation-actuated closure mechanism which, pre-positioned on the centrifuge rotor, moves automatically into a closed position by virtue of the intrinsic weight of the lid.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a lid for closing a centrifuge rotor. 
     BACKGROUND OF THE INVENTION 
     Centrifuges are devices with which containers can be subjected to centrifugal force. In the laboratory, for example, suspensions in test tubes can be treated in this way in order to precipitate the floating solid material at the bottom of the test tube. As a rule, centrifuges have a rotary drive with a vertical drive shaft, on which a rotor can be placed. Normally provided in the rotor are compartments, into which containers which are to be centrifuged can be inserted. The rotors of the centrifuge are often interchangeable, in order to centrifuge vessel contents in one of the rotors while other rotors are only just being loaded with containers, or can be ready for further processing together with containers already centrifuged. 
     Since, for example, test tubes are pushed into the rotors so as to be open at the top, operational reliability is served, inter alia, by keeping the containers in a liquid-tight chamber during the centrifuging in the rotor. On the other hand, this chamber should be accessible as well as possible for the purpose of simple loading. Since, in particular in the laboratory, a number of actions are often carried out at the same time and the centrifuges nevertheless have to be closed carefully, it is particularly advantageous to be able to use devices having as few actions as possible, having as little actuating movement as possible and, if at all possible, operationally reliably with only one hand. In this regard, known centrifuges need improvement. 
     SUMMARY OF THE INVENTION 
     The present invention is based on the object of devising a lid for closing a centrifuge rotor in which the handling is simplified. 
     According to the invention, this object is achieved by a lid having the features of claim  1  or  11 . Preferred refinements of the invention are specified in the subclaims. 
     According to the invention, a lid for closing a centrifuge rotor is characterized by a form-fitting rotation-actuated closure mechanism which, pre-positioned on the centrifuge rotor, moves automatically into a closed position by virtue of the intrinsic weight of the lid. As a preferred refinement of the same or alternatively, a closure mechanism of the lid according to the invention indicates the closed end position of the lid on the centrifuge rotor acoustically, in particular by means of a snapping or clicking noise. 
     For instance, a lid according to the invention can be rotationally symmetrical about a substantially vertical axis—preferably the axis of rotation of the rotor—and (similarly to a cooking pot lid having a central knob) can have a central grip knob, with which the lid can be placed on the rotor from above. Then, if the closure mechanism is for example a movement thread having a sufficiently large slope angle then, after being pre-positioned at the start of the thread, the lid can rotate automatically into a closed position by virtue of the intrinsic weight of the lid, guided in the thread. The closure mechanism preferably comprises a locking means at the completely closed position of the lid—for example at the end of the thread. In this way, therefore, given this configuration according to the invention, it is sufficient to pre-position the lid on the rotor from above with one hand on the grip knob, then to release it, so that it itself rotates downward into a virtually closed position and, finally, to turn it further by a few degrees on the same grip knob, so that the lid locks in a closed position in a then liquid-tight manner. 
     The locking means can be form-fitting, for example by the lid being seated on its seals, which effect the tightness, before being locked and, for example, counter to its resilient deformability, then coming to lie with a form fit over a locking ledge with a pin in a locking undercut. 
     The locking mechanism provided can—to a certain extent in a way similar in function to a thread—also be a bayonet, for example of the type as is known and widespread for interchangeable objectives on reflex cameras. In addition, the spring-prestressed locking means known from there, also having an actuating lever for releasing the locking means, can in principle be taken over directly for the lid according to the invention. 
     These and other features of the invention and their possible refinements will be described below with reference to the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a sectioned side view of a centrifuge rotor and a lid therefor, 
         FIG. 2  shows a sectioned side view of the centrifuge rotor according to  FIG. 1  with the lid in the (virtually) closed position, 
         FIG. 3  shows a three-dimensional sectioned view of the centrifuge rotor with lid according to  FIG. 1 , and 
         FIG. 4  shows a three-dimensional view of the closure mechanism of the centrifuge rotor according to  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  reveals a centrifuge rotor  2 , above which a lid  4  is depicted, as is placed on the centrifuge rotor  2  by a hand (not illustrated) of a user. The centrifuge rotor  2  has a row of holes or compartments  6  distributed uniformly on the rotor periphery, into which test tubes (not illustrated) can be plugged, oriented obliquely outward at the bottom. Overall, the rotor is rotationally symmetrical about a vertical axis  8  and, at the center, has a vertical central hole  9 , by means of which the rotor  2  can be plugged on to a centrifuge drive shaft (not illustrated) for the centrifuging. 
     The compartments  6  for test tubes are accessible through a large circular opening  10  in the top of the rotor  2 . They are located on the radial outer wall of a bowl-like chamber  11 , which extends annularly around a central hub  12 . 
     Arranged in the bottom side of the hub  12  is the hole  9  for a centrifuge rotor drive shaft. Toward the top, the hub  12  projects to a certain extent circularly cylindrically out of the opening  10  and there forms a substantial element of a closure mechanism  14  of the lid  4 . To be specific, the lid  4 , which is circularly cylindrical in plan view, has in the top side of its centre a grip knob  16  projecting circularly cylindrically upward, which is hollow on the underside, therefore so to speak has the form of a cup or hat. Gripped from above, for example, the knob  16  with the lid  4  as a whole can be placed on the upper end  18  of the hub  12  and thus pre-positioned. Without further rotational movement, first of all the lid  4  falls vertically downward with the cup-like knob  16  along the vertical axis  8  on account of its intrinsic weight over the upper end  18  of the hub  12 , until three thread pins  20  which project radially inward in the cup-like knob and which are distributed uniformly on the periphery of the internal space  22  of the cup-like knob  16  come to lie on the upper edge of the upper end  18  of the hub  12 . 
     Pre-positioned in this way, because of its intrinsic weight, the lid  4  slips further downward along the vertical axis  8  and, in the process, is set rotating in the clockwise direction by a three-start thread  24 . The three-start thread  24  in the hub  12  can be seen particularly well in the three-dimensional view of  FIG. 4 . Looking at  FIG. 4 , the three-start thread  24  extends spirally downward on the periphery of the hub  12  in the form of three spiral grooves  24 . The grooves  24  have such a width that the thread pins  20  can run in them, guided in the interior of the cup-like knob  16  but without jamming. Thus the lid  4  moves downward automatically by virtue of its intrinsic weight, rotating about the vertical axis  8 , until its O-ring seal  26  (on the underside on the outermost rim of the lid) comes to lie on the upper edge of the rotor opening  10 . This position of the lid  4  on the rotor  2  can be seen in  FIG. 2 . 
     Only in this position is it necessary for the user to grip the knob  16  once more (on the top of the lid) for the final liquid-tight closure of the lid  4  on the rotor  2  and to rotate it by a few degrees in order to lock the lid  4  on the rotor  2 . Then, again looking at  FIG. 4 , it can be seen that, as the closure mechanism, the grooves  24  of the three-start thread have at their lower end a locking position  27  for the thread pin  20  behind a ledge  28 . By means of active further rotation of the lid  4 , guided by its thread pins  20  in the thread turns  24 , the thread pins  20  then overcome the ledges or “humps”  20  counter to the prestress of the resilient seal  26 , which is pressed in a liquid-tight manner into a sealing groove  30  on the outer rim of the rotor opening  10 . Behind the humps  28 , the thread pins  20  are then located and locked with a form fit in the locking positions  27  at the end of the thread turns  24 .