Abstract:
The invention relates to a rotary evaporator having an apparatus for the securing of a ground joint including a ground sleeve and a ground core between an evaporator flask and a steam leadthrough, wherein the securing device has a fastening section at the ground core side and a snap connector at the ground sleeve side and pivotably supported at the fastening section at the ground sleeve side between a release position and a holding position in order selectively to release or firmly hold the piece of laboratory equipment at the ground sleeve side.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of German Patent Application DE 102009006816.3 filed Jan. 30, 2009. 
       FIELD OF THE INVENTION 
       [0002]    The present application relates to a rotary evaporator having an apparatus for the securing of a ground joint, in particular a ground glass joint, including a ground core between an evaporator flask and a steam leadthrough. 
       BACKGROUND OF THE INVENTION 
       [0003]    A rotary evaporator is a piece of laboratory equipment which includes a heating bath and an evaporator flask which can dip into the heating bath. In operation, a liquid medium present in the heating bath, for example water or—for higher temperatures—oil, is heated in order thus to heat the evaporator flask dipped into the heating bath. A liquid mixture contained in the evaporator flask can hereby be heated so that the respective distillate, in particular solvent, is evaporated. The evaporated distillate then flows into a cooler of the rotary evaporator to condense there. The condensate is subsequently collected in a collection flask. The distillation residue remaining in the evaporator flask can be further processed or analyzed. A vacuum pump is frequently additionally provided for the generation of a vacuum in the evaporator flask and in the cooler to lower the boiling point, whereby the distillation can be accelerated and the distillation rate can be increased. 
         [0004]    A rotary evaporator furthermore includes a rotary drive for the rotation of the evaporator flask in the heating bath. The evaporator flask is uniformly heated due to the rotation and a thin liquid film, which has a large surface and from which the distillate can be evaporated fast, efficiently and gently, is produced at the heated inner wall of the evaporator flask. 
         [0005]    In order to set the rotary damper into rotation which is, for example, rotationally fixedly connected to the initially named steam leadthrough via a ground joint, the steam leadthrough, which is usually formed as a hollow glass shaft and which serves to conduct the evaporated distillate from the evaporator flask to the cooler, is rotatingly driven by the rotary drive. Such a ground joint is usually secured using a Keck clamp. 
         [0006]    With a Keck clamp, two respective snap connectors of part ring shape which extend in two planes parallel to one another are connected via a plurality of webs. To secure the ground joint, the Keck clamp is placed on such that the one of the two snap connectors engagingly surrounds the ground sleeve of the evaporator flask behind a flanged rim of the ground sleeve and the other of the two snap connectors engagingly surrounds the ground core of the steam lead through behind a collar adjoining the ground core. 
         [0007]    A widening of the one snap connector also directly results in a widening of the other snap connector due to the web coupling. This is a disadvantage when the section of the ground joint engaged around either at the ground sleeve side or at the ground core side has a larger outer diameter than expected, as is frequently the case due to deviations in the production of glass devices. It can, for example, occur that the ground sleeve of the evaporator flask has too large an outer diameter at the engaged around section, whereby the snap connector at the ground sleeve side is widened accordingly and then also the snap connector at the ground core side via the web coupling. In the extreme case, the widening can be so wide that with a loose ground joint the snap connector at the ground core side can slip over the collar and thus the evaporator flask can slip from the steam leadthrough. 
       SUMMARY OF THE INVENTION 
       [0008]    It is the underlying object of the invention to provide a rotary evaporator of the initially named kind which can ensure a reliable securing of a ground joint. 
         [0009]    This object is satisfied by a rotary evaporator having the features of claim  1  and in particular in that the securing apparatus has a fastening section at the ground core side and a snap connector at the ground sleeve side and pivotably supported at the fastening section between a release position and a holding position in order selectively to release or firmly hold the piece of laboratory equipment, in particular the evaporator flask, at the ground sleeve side. 
         [0010]    The fastening section can be fastened or mounted—in particular without forming a snap connection—to a component through which the piece of laboratory equipment, in particular the steam leadthrough, at the ground core side can be guided, in particular to a clamping member for the clamping of a clamping insert for the clamping of the steam leadthrough in a hub of a rotary drive of the rotary evaporator, or directly to the piece of laboratory equipment at the ground core side. The fastening section is preferably made in ring shape, in particular in closed ring shape. 
         [0011]    At the ground sleeve side, in contrast, a snap connector supported at the fastening section is provided. The in particular hoop-like snap connector is pivotable between a release position and a holding position. In the release position, the piece of laboratory equipment, in particular the evaporator flask, at the ground sleeve side is released from the snap connector. In the holding position, the snap connector is snapped onto the ground sleeve of the piece of laboratory equipment at the ground sleeve side, i.e. the piece of laboratory equipment at the ground sleeve side is held by the snap connector, in particular by form fitting. 
         [0012]    The apparatus in accordance with the invention satisfies its securing function independently of a diameter variation of the neck of the piece of laboratory equipment, in particular of the evaporator flask, at the ground sleeve side. The piece of laboratory equipment at the ground sleeve side can—in particular independently of the position of the fastening section at the aforesaid component—be firmly held by the securing apparatus for as long as the snap connector is in the holding position. 
         [0013]    In contrast to a Keck clamp, the securing apparatus in accordance with the invention only has one snap connector. A deformation of the snap connector at the ground sleeve side in particular has no return effect on the fastening and/or on the shape of the fastening section at the ground core side. 
         [0014]    In accordance with an embodiment of the invention, the fastening section is formed as a ring nut, in particular having an internal thread. The ring nut can in particular be able to be screwed onto an external thread of the aforesaid component or of the piece of laboratory equipment at the ground core side. A ring nut ensures a fastening of the securing apparatus which can be established fast and simply. The ring nut can furthermore also be held in a manner secure against losing in the release position of the snap container, for example at the aforesaid component. 
         [0015]    The snap connector can have only one pivot arm to which the snap connector is pivotally connected at the fastening section. The snap connector, however, preferably has two pivot arms for a particularly stable and robust connection, said two pivot arms each being pivotally connected to the fastening section from two sides of the fastening section which are mutually opposite, in particular mutually diametrically opposite. 
         [0016]    The snap connector in particular includes a holding section which is adapted to engage behind a flanged rim of a piece of laboratory equipment at the ground sleeve side in the holding position of the snap connector. To enable a snap connection between the snap connector and a piece of laboratory equipment at the ground sleeve side, it is preferred if the holding section of the snap connector is formed in part ring shape with a circle arc extending over more than 180°. The holding section is preferably designed spring elastically deformably. 
         [0017]    The holding section can define a plane which extends at least substantially perpendicular to a longitudinal axis and/or to an axis of rotation of the fastener section in the holding position of the snap connector. In the holding position, the aforesaid pivot arms can extend parallel to the aforesaid longitudinal axis and/or axis of rotation of the fastening section. 
         [0018]    In accordance with another embodiment of the invention, the fastening section is centrally passed through by the pivot axis of the snap connector. A securing apparatus can be provided by the central pivotal connection of the snap connector to the fastening section which has a particularly compact form both in the release position of the snap connector and in the holding position. 
         [0019]    The pivot range of the snap connector preferably has a value between 60° and 120°. The aforesaid value is particularly preferably at least substantially 90°. The pivot range limits are preferably each preset by an abutment. 
         [0020]    In accordance with a further embodiment of the invention, the fastening section has a press-off section and/or a press-off mechanism by which the piece of laboratory equipment at the ground sleeve side can be pressed off the piece of laboratory equipment at the ground core side. This is in particular of advantage when the ground joint is jammed and can no longer be released in a different manner. 
         [0021]    To be able to easily actuate the fastening section, in particular to facilitate a screwing onto an external thread, a gripping corrugation is provided at the outer surface of the fastening section. 
         [0022]    The fastening section and the snap connector are preferably each formed in one piece and/or from plastic. 
         [0023]    A clamping member for the clamping of a clamping insert for the clamping of the steam leadthrough in a hub of the rotary drive of the rotary evaporator can be provided, with the securing apparatus being fastenable to the clamping member and the clamping member being fastenable to a rotary drive of the rotary evaporator. 
         [0024]    The clamping member is in particular formed as a clamping ring nut having an internal thread, with the clamping ring nut being able to be screwed onto the hub of the rotary drive. 
         [0025]    The invention furthermore relates to an apparatus for the securing of a ground joint including a ground sleeve and a ground core between two piece of laboratory equipment, in particular between an evaporator flask and a steam leadthrough of a rotary evaporator, with the securing apparatus having a fastening section at the ground core side and a snap connector at the ground sleeve side pivotally supported at the fastening section between a release position and a holding position in order selectively to release or firmly hold the piece of laboratory equipment at the ground sleeve side. 
         [0026]    Advantageous further developments of the securing apparatus in accordance with the invention result in an analog manner from the further developments described above with respect to the rotary evaporator in accordance with the invention. 
         [0027]    Advantageous embodiments of the invention are also set forth in the dependent claims, in the description of the Figures and in the drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will be described in the following by way of example with reference to the drawing. There are shown, schematically in each case: 
           [0029]      FIG. 1  a perspective view of a rotary evaporator; 
           [0030]      FIG. 2   a  a part cross-section along a longitudinal axis of a hub of a rotary drive of a rotary evaporator having an inserted clamping sleeve and an inserted steam leadthrough as well as a ground joint and an evaporator flask; 
           [0031]      FIG. 2   b  an enlarged detail of the region A from  FIG. 2   a;    
           [0032]      FIG. 3  a perspective view of the clamping sleeve of  FIG. 2   a;    
           [0033]      FIG. 4  the hub of  FIG. 2   a  in an enlarged individual representation; 
           [0034]      FIG. 5  a perspective view of the ground clamp of  FIG. 2   a  in a holding position; and 
           [0035]      FIG. 6  a perspective view of the ground clamp of  FIG. 2   a  in a release position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    The rotary evaporator  9  shown in  FIG. 1  includes a rotary drive  11  for an evaporator flask  13 , in particular of glass, which is shown only in  FIG. 2  and is designed as a round bottomed flask or a V-shaped flask or the like and which can be heated in a heating bath, not shown, to evaporate distillate from a liquid mixture present therein. The evaporated distillate then moves via a steam leadthrough  15 , in particular formed as a hollow glass shaft, which is guided through the rotary drive  11  and of which only a ground core projecting obliquely downwardly from the rotary drive  11  can be recognized in  FIG. 1  into a cooler  17  to condensate there. The condensed distillate is then collected in a collection flask  19 . 
         [0037]    A vacuum connection  21  is provided at the cooler  17  to apply a vacuum generated by a vacuum pump at the cooler  17  and at the evaporator flask  13 , whereby the boiling point for the distillate can be lowered. The rotary evaporator  9  additionally includes a lift  23  which carries the rotary drive  11  and can move it in the vertical direction to lower the evaporator flask  13  into the heating bath or to lift it out of it. The rotary evaporate  9  furthermore includes an operating unit  25  for the control of the heating bath, of the rotary drive  11 , of the vacuum pump and of the lift  23 . 
         [0038]    The steam leadthrough  15  is pushed through a hub  27  of the rotary drive  11  ( FIG. 2 ) and is clamped in the hub  27  via a clamping sleeve  29  which is located between the hub  27  and the steam leadthrough  15  so that a rotation of the hub  27  of the rotary drive  11  about a longitudinal axis  31  of the hub  27  results in a corresponding rotation of the clamping sleeve  29 , of the steam leadthrough  15  and of the evaporator flask  13  rotationally fixedly connected to the stream leadthrough  15 . The longitudinal axis  31  is in this respect—in the assembled state of the rotary evaporator  9 —a common longitudinal axis  31  of the hub  27 , of the clamping sleeve  29 , of the steam leadthrough  15  and of the evaporator flask  13 . The hub  27 , the clamping sleeve  29  and the steam leadthrough  15  are arranged concentrically to one another. 
         [0039]    The rotationally fixed connection between the steam leadthrough  15  and the evaporator flask  13  is ensured by a ground joint, in particular a conical ground joint, in which the steam leadthrough  15  engages with its side which faces the evaporator flask  13  and at which a ground core is formed into a ground sleeve formed at a flask neck of the evaporator flask  13 . A ground clamp  33  is provided to secure the ground joint, in particular formed as a ground glass joint, between the steam leadthrough  15  and the evaporator flask  13 . 
         [0040]    The clamping sleeve  29  having rotational symmetry, in particular three-fold rotational symmetry, and comprising plastic includes in accordance with  FIG. 3  a front axial end  35  and a rear axial end  37 . The clamping sleeve  29  is inserted front end  35  first into the hub  27  of the rotary drive  11  of the rotary evaporator  9 . Directly adjoining the front end  35 , the clamping sleeve  29  has a front clamping section  39  whose outer diameter expands conically to the rear. A further such rear clamping section  41  is provided in the rear region of the clamping sleeve  29  and its maximum outer diameter is larger than the maximum outer diameter of the front clamping section  39 . Since the inner diameter of the clamping sleeve  29  is constant in each case in the region of the clamping sections  39 ,  41 , the wall thickness of the clamping sleeve  29  increases accordingly in the region of the clamping sections  39 ,  41 . 
         [0041]    The clamping sleeve  29  has in each case at its two ends  35 ,  37  three elongate incisions or openings  43  open toward the respective end  35 ,  37 , with the respective openings  43  being provided distributed equally in the peripheral direction of the clamping sleeve  29  at each of the two sides  35 ,  37 . An opening  43  of the first end  35  and an opening of the second end  37  are in each case arranged along a straight line parallel to the longitudinal axis  31 ′ of the clamping sleeve  29 . 
         [0042]    The respective opening  43  extends in the longitudinal direction  31 ′ of the clamping sleeve  29  and, coming from the respective end  35 ,  37 , beyond the first or second clamping sections  39 ,  41  respectively. Each of the two clamping sections  39 ,  41  is hereby divided into three clamping segments  45  of part ring shape which are arranged along a circular line extending concentrically to the longitudinal axis  31 ′ of the clamping sleeve  29 . 
         [0043]    Expressed differently, the clamping sleeve  29  is divided into three longitudinal sections of part sleeve shape which together form the sleeve-like basic shape of the clamping sleeve  29  and are held fixedly to one another via connection webs  95  extending in the peripheral direction. A respective one of the connection webs  95  is arranged between a respective two of the longitudinal sections of part sleeve shape, with the connection webs  95  being arranged at the same level viewed in the longitudinal direction of the clamping sleeve  29 . 
         [0044]    A middle section  47  of the clamping sleeve  29  is arranged between the two clamping sections  39 ,  41 . The middle section  47  includes a cylindrical recess  49  and two ring webs  51  which bound the recess  49  in the longitudinal direction  31 ′ of the clamping sleeve  29 , extend in the peripheral direction, project radially outwardly and are, however, interrupted by the openings  43 . The two ring webs  51  each have a constant outer diameter which is the same. 
         [0045]    A further such rear ring web  53  is furthermore provided between the rear clamping section  41  and the rear end  37  of the clamping sleeve  29 . The outer diameter of the rear ring web  53  is constant in this respect and corresponds to the maximum outer diameter of the rear clamping section  41 . In addition, the clamping sleeve  29  includes at its inner surface, which is otherwise formed at least substantially cylindrically, two ring webs  75  which each extend in the peripheral direction and project radially inwardly. 
         [0046]    As can be seen from  FIG. 4 , the hub  27  has a front axial end  55 , a rear axial end  57  and two contact sections  59 ,  61  which are arranged spaced apart from one another in the longitudinal direction  31  of the hub  27 , with the mutual spacing of the two contact sections  59 ,  61  corresponding to the mutual spacing of the two clamping sections  39 ,  41  of the clamping sleeve  29 . The contact sections  59 ,  61  each have an inner cross-section expanding conically toward the rear end  57  of the hub  27 . The maximum inner cross-section of the rear contact section  61  is in this respect larger than the maximum inner cross-section of the front contact section  59 . 
         [0047]    The front contact section  59  of the hub  27  forms a counter-shape to the front clamping section  39  of the clamping sleeve  29 ; the rear contact section  61  of the hub  27  forms a counter-shape to the rear clamping section  41  of the clamping sleeve  29 . The hub  27  is in each case formed cylindrically at the inner side between the two contact sections  59 ,  61 , i.e. at a middle hub section  63 , and from the respective contact section  59 ,  61  toward the respective end  55 ,  57 . 
         [0048]    The clamping sleeve  29  already pushed into the hub  27  and contacting the contact sections  59 ,  61  of the hub  27  with its clamping sections  39 ,  41  is axially loaded with force for the clamping of the steam leadthrough  15  in the hub  27  of the rotary drive  11  of the rotary evaporator  9 . The front or rear clamping section  39 ,  41  of the clamping sleeve  29  in this respect runs onto the front or rear conical contact section  59 ,  61  of the hub  27 , whereby the two clamping sections  39 ,  41  are urged radially inwardly and thus toward the steam leadthrough  15 . 
         [0049]    The axial force loading is provided by a clamping ring nut  65  ( FIG. 2 ) which presses onto a ring shaped end face  69  formed at the rear end  37  of the clamping sleeve  29  and extending radially to the longitudinal axis  31 . For this purpose, the clamping ring nut  65  includes an internal thread with which the clamping ring nut  65  is screwed onto the hub  27  whose rear end  57 , at which an external thread  67  corresponding to the internal thread of the clamping ring nut  67  is formed, projects from the rotary drive  11 . Clamping sleeve  29  is hereby axially clamped. 
         [0050]    In the assembled state, the steam leadthrough  15  is clamped in the hub  27  by the clamping sleeve  29 . It can in this respect be achieved by the openings  43  formed in the clamping sleeve  29  that the clamping sections  39 ,  41  can be compressed radially inwardly more easily. To define a relative axial alignment of the steam leadthrough  15  to the clamping sleeve  29 , a peripheral web  97  is formed at the inner surface of the clamping sleeve  29  and engages into a groove  107  formed at the outer surface of the steam leadthrough  15  as a counter-shape ( FIG. 5 ). A peripheral centering section  101  projects axially from the second rear end  37  of the clamping insert formed as a clamping sleeve  29 ; it is in particular formed in wedge shape, is in particular interrupted and is arranged in the assembled state of the clamping sleeve  29 , viewed in the radial direction, between the steam leadthrough  15  and an outer wall section of the clamping ring nut  65 . 
         [0051]    A peripheral free space  71  is formed between the hub  27  and the clamping sleeve  29  in the middle region  47  of the clamping sleeve  29  due to the recess  49  which runs around there ( FIG. 2   b ). A clamping sleeve  29  which swells up as a consequence of contact with distillate can expand into the free space  71  without a fixing of the steam leadthrough  15  in the hub  27  necessarily occurring here. This also applies in another respect to a free space  73  which is formed in the axial direction between the two ring webs  75  and in the radial direction between the clamping sleeve  29  and the steam leadthrough  15 . 
         [0052]    A good centration of the steam leadthrough  15  in the hub  27  of the rotary drive  11  of the rotary evaporator  9  and thus a good true running of the steam leadthrough  15  can be achieved by the clamping sleeve  29  with its two clamping sections  39 ,  41  and the hub  27  formed in counter-shape thereto and having the two contact sections  59 ,  61 . This is in particular of advantage since a sealing ring  77  which is provided close to the front clamping section  39  and which is arranged between the steam leadthrough  15  rotating in operation and a cooler connection  79  of the stationary cooler  17  is hardly loaded in this respect. The sealing ring  77  consequently has a high operating life. Furthermore, the contact surfaces between the steam leadthrough  15  and the clamping sleeve  29  and between the clamping sleeve  29  and the hub  27  can be minimized by the clamping sleeve  29 . 
         [0053]    The ground clamp  33  releasably connectable to the apparatus is shown in more detail in  FIGS. 5 and 6  and includes at the ground core side, i.e. at its side facing the steam leadthrough  15 , a ring nut  81  and at the ground sleeve side, i.e. at its side facing the evaporator flask  13 , a clamp connector  83 . The ground clamp  33  is shown together with the steam leadthrough  15  and the evaporator flask  13  in  FIG. 5 . For reasons of clarity, the clamping ring nut  65  is omitted in  FIG. 5 . The ground clamp  33  is shown in an individual representation in  FIG. 6 . 
         [0054]    The ring nut  81  has an internal thread with which the ring nut  81  can be screwed onto an external thread of the aforesaid clamping ring nut  65 . The ground clamp  33  can be attached or fastened secure against losing at the hub  27  of the rotary drive  11  of the rotary evaporator  9  via the ring nut  81 —in particular under the agency of the aforesaid clamping ring nut  65 . To facilitate a screw rotation of the ring nut  81 , it—just like the clamping ring nut  65 —is provided with a gripping corrugation at its outer surface. 
         [0055]    The at least substantially hoop-shaped snap connector  83  is pivotably and centrally supported at the ring nut  81 . The snap connector  83  includes two pivot arms  85  which are each pivotally connected to one of two sides of the ring nut  81  disposed diametrically opposite one another with respect to the longitudinal axis and/or the axis of rotation of the ring nut  81 . The snap connector  83  furthermore includes a holding section  87  of partly ring shape. The snap connector  83  is pivotable between a holding position shown in  FIGS. 1 ,  2  and  5  and securing the ground joint and a release position shown in  FIG. 6 . 
         [0056]    The ring nut  81  and the snap connector  83  are each formed in one piece and from plastic. To form the ground clamp  33  and the pivotable support of the snap connector  83  at the ring nut  81 , the snap connector  83  is latched via openings formed in the pivot arms  85  to pivot spigots  91  formed at the two diametrically opposed sides of the at the ring nut  81 . The pivot range of the snap connector  83  amounts to approximately 90° and is bounded by the opening angle of a pivot recess  99  associated with the respective pivot arm  83 . 
         [0057]    The holding section  87  of part circle shape  87  is formed open at that side which runs ahead on a pivoting of the snap connector  83  from the release position into the holding position. As can be recognized from  FIG. 2   a , a plane is defined by the holding section  87  which extends at least substantially perpendicular to the longitudinal axis and/or the axis of rotation of the ring nut  81  in the holding position of the snap connector  83 . 
         [0058]    In the holding position, the holding section  87  of the snap connector  83  engages behind a flanged rim  89  formed at the ground sleeve of the evaporator flask  13  and snaps into the ground sleeve of the evaporator flask  13 . To ensure a snapping in, the holding section  87  of part circle shape extends over a circle arc of more than 180° and is formed sufficiently spring elastically deformably at least the two ends of the part circle. The evaporator flask  13  is held by form fitting by the snap connector  83  in the holding position. The evaporator flask  13  can in particular also be held by the snap connector  83  when the snap connector  83  is no longer completely screwed onto the clamping ring nut  65 . 
         [0059]    In the release position in accordance with  FIG. 6 , the snap connector  83  is pivoted away from the longitudinal axis and/or the axis of rotation of the ring nut  81  by approximately 90° with respect to the holding position shown in  FIGS. 1 ,  2  and  5  to release the flask neck and thus the evaporator flask  13 . 
         [0060]    The ring nut  81  furthermore has a prolongation which extends in the direction of the evaporator flask  13  and which is formed as a press-off section  93 . If the ground joint which is not (no longer) secured can no longer be released, i.e. if the evaporator flask  13  can no longer be pulled off the steam leadthrough  15 , a pressing off of the evaporator flask  13  can be achieved by unscrewing the ground clamp  33  or the ring nut  81  from the clamping ring nut  65 . 
         [0061]    A reliable and simple securing of the ground joint between the steam leadthrough  15  and the evaporator flask  13  can be achieved by the ground clamp  33 . Deviations in the diameter of the ground sleeve and/or of the flask neck of the evaporator flask  13  from a standard diameter or from an expected diameter can be tolerated and have no return effect on the fastening of the ring nut  81  at the clamping ring nut  65  or at the rotary drive  11 .