Abstract:
Tube roller pumps for blood treatment devices are disclosed. The pumps include a curved surface with a rotor rotatable therein. The rotor attaches via a reception means to a drive shaft of the pump. The rotor has a first locking element for axially locking the rotor on the shaft and a second locking element for rotationally coupling the shaft and the rotor. The reception means and the drive shaft guide the rotor to a position on the shaft, when pushed onto the shaft, and, at this position, the first element may be moved by the shaft from locked to released. The rotor, when pushed further onto the shaft, is moved to another position at which the first element is automatically moved back to locked and the second element may be brought into manual engagement with the shaft to transmit torque from the shaft to the rotor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Patent Application No. DE 10 2012 105 913.6 filed Jul. 3, 2012, the contents of such application being incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a tube roller pump (peristaltic pump) for a medical device for extracorporeal blood treatment, comprising a pump housing including a curved running surface (bearing surface) and a rotor that is rotatable within the running surface, a tube segment being adapted to be placed between the running surface and the rotor. The rotor is adapted to be attached via a shaft reception means to a drive shaft of the tube roller pump, and at least one locking element is provided for axially locking and/or rotationally coupling the rotor to the drive shaft. 
         [0003]    The invention additionally relates to a medical device for extracorporeal blood treatment, which comprises such a tube roller pump. 
       BACKGROUND INFORMATION 
       [0004]    In medical devices for extracorporeal blood treatment (dialysis) tube roller pumps are frequently used, which convey the blood drawn from the patient to a dialyzer and return it to the patient. Such tube roller pumps operate peristaltically, with a loop-shaped tube segment abutting on an appropriately curved running surface of the pump housing. A pump rotor, which is located within the running surface, then moves with its outer edges, or rather with rollers attached thereto, along the tube segment. In so doing, it locally squeezes the tube thus allowing, on the basis of the elastic properties of the material of the tube segment, blood to be conveyed through the tube segment. To this end, the blood is supplied to the tube segment via a first connection and removed therefrom via a further connection at the other end of the tube segment. The tube segment thus forms, e.g. together with the supply and discharge lines and a plurality of air traps, a so-called transfer system with which the patient&#39;s blood is conveyed to a dialyzer and back to the patient. 
       DESCRIPTION OF THE RELATED ART 
       [0005]    German patent application DE 10 2007 020 573 A1, by way of example, discloses such a tube roller pump with a stator, a rotor and a rotor drive, in the case of which a tube is placed between the rotor and the tube roller path of the stator. By rotation of the rotor and the resultant revolving movement of tube rollers, the tube is pressed against the tube roller path of the stator so that liquid is pumped through the tube. 
         [0006]    Also U.S. Pat. No. 7,547,200 B2 discloses such a peristaltic pump with a rotor and rollers, which press an inserted tube against a semicircular tube roller track. The roller track has at one end thereof a beveled edge for receiving the tube, which is attached to a cartridge. 
       SUMMARY OF THE INVENTION 
       [0007]    The transfer systems used for such pumps in the field of medical technology are normally exchanged after each treatment and not reused for other patients. Therefore, a used tube segment must be removed from the pump prior to installing a new transfer system in the device. 
         [0008]    In addition, also the rotor of such a system is normally removed after each treatment for the purpose of cleaning, and reinstalled after cleaning. In order to simplify the handling of the rotor during this operation, systems have already been developed which make use of radial and axial positive locking for transmitting torque from the drive shaft to the rotor. Rotors having this kind of structural design may especially be provided with bayonet locking devices in combination with an additional locking element. The additional locking element may e.g. be a lever that must be turned for locking the rotor. However, such systems necessitate at least four handling steps during the installation operation, since the second locking element must first be turned for rotational coupling, before the rotor can be attached to the drive shaft and rotated by approx. 90° so as to lock the bayonet locking device. Subsequently, the locking element must be turned again to finally lock the rotor. 
         [0009]    It is therefore an object of the present invention to provide a tube roller pump for a medical device for extracorporeal blood treatment, which comprises a rotor and allows said rotor to be installed with the least possible number of easily executable handling steps. 
         [0010]    It is also an object of the present invention to provide a medical device for extracorporeal blood treatment, which includes a tube roller pump suitable for having installed therein such a rotor. 
         [0011]    According to aspects of the invention, this object is achieved by a tube roller pump (peristaltic pump) according to the independent claim  1 . Advantageous further developments of the tube roller pump can be seen from subclaims  2 - 12 . An object is also achieved by a medical device for extracorporeal blood treatment according to claim  13 . 
         [0012]    The tube roller pump according to aspects of the present invention, which is used for a medical device for extracorporeal blood treatment, comprises a pump housing including a curved running surface (bearing surface) and a rotor that is rotatable within the running surface, a tube segment being adapted to be placed between the running surface and the rotor. The rotor is adapted to be attached via a shaft reception means to a drive shaft of the tube roller pump, and at least one locking element is provided for axially locking and/or rotationally coupling the rotor to the drive shaft. 
         [0013]    According to aspects of the invention, the rotor has provided thereon a first locking element for selective axial locking of the rotor on the drive shaft and a second locking element for selective rotational coupling of drive shaft and rotor. The geometry of the shaft reception means of the rotor and that of the drive shaft are configured such that the rotor is adapted to be guided to a first predetermined rotary position relative to the drive shaft, when it is axially pushed onto the drive shaft. At this first position, the first locking element is adapted to be moved by the drive shaft from a locking position to a release position. The rotor, when pushed further onto the drive shaft, is thus adapted to be moved to a second, axially defined position at which the first locking element is adapted to be moved back to the locking position, in particular automatically, and the second locking element is adapted to be brought, in particular manually, into engagement with the drive shaft such that a torque can be transmitted from the drive shaft to the rotor. 
         [0014]    Due to this structural design of the rotor and of the drive shaft of the pump, the rotor is, on the one hand, auto-orientable, since it will automatically be guided to the correct, radially defined position, when the operator pushes the rotor axially onto the drive shaft. At this position, the rotor can be radially locked by the second locking element, so that a torque can be transmitted from the drive shaft to the rotor. The rotor is here automatically rotated to the correct position by the user, and the geometry supports the user in finding this position. This makes the installation process much easier for the operator. 
         [0015]    On the other hand, the rotor is also auto-lockable, since it is automatically locked by the first locking element during the attachment process, without any extra activity being necessary on the part of the operator during the process of installation. Prior to installation, the locking element already occupies the locking position from which it is only temporarily moved to the release position by the drive shaft before it is automatically returned. Hence, the temporary unlocking does not necessitate any additional activity either, but the drive shaft unlocks the locking element automatically during the installation process, and the first locking element is configured such that it will automatically be relocked, when the rotor has arrived at a second, axially defined position. At this position, the rotor also occupies an axially defined position in which the second locking element can be brought into engagement with the drive shaft so as to prevent relative rotation between the rotor and the drive shaft or establish a rotational coupling therebetween. 
         [0016]    Hence, the rotor is ready for use at this position, and the first locking element can axially lock the rotor preferably only at this position. The previously radially defined position allows axial locking of the rotor and the positioning of the drive shaft relative to the second locking or force transmitting element. 
         [0017]    Taking all this into account, it is therefore possible to establish, with only one handling step, axial locking and anti-rotation locking of a releasable shaft-to-collar connection. In particular, the system allows single hand operation, since the rotor can be grasped with one hand by the user, and pushed onto the drive shaft. In the demounted condition of the rotor, it is also easily possible to clean the drive shaft. 
         [0018]    One embodiment of the invention is so conceived that, at the first, radially defined position, the first locking element is adapted to be moved by means of the drive shaft from a locking position to a release position against the force of a spring, whereas, at the second, axially defined position, it is adapted to be moved back to the locking position by the force of said spring. Automatic unlocking and renewed locking, caused by the axial movement of the rotor on the drive shaft, can thus be realized easily. 
         [0019]    The drive shaft and the shaft reception means may both have slide geometries sliding along one another, whereby the rotor, while being axially pushed onto the drive shaft, is guided to the first, radially defined position relative to the drive shaft. A preferred embodiment is so conceived that, at the first, radially defined position, the first locking element is then adapted to be moved from the locking position to the release position through the slide geometry of the drive shaft. This has the advantage that the slide geometry of the drive shaft can be used for rotationally orientating the rotor relative to the drive shaft as well as for unlocking the first locking element. 
         [0020]    The slide geometry of the drive shaft may e.g. be defined by a gable-shaped end portion, whereby two oblique surfaces are formed. These oblique surfaces then slide along the complementary slide geometry of the shaft reception means, whereby the rotor will rotate to the desired rotary position. Furthermore, the oblique surfaces push the first locking element to the side, which has the effect that also the locking element slides along an oblique surface. 
         [0021]    According to one embodiment of the invention, the slide geometry of the shaft reception means is defined by two triangular plates, which are formed on the inner wall of the shaft reception means and extend in parallel opposed relationship with one another, a tip of each of these triangular plates pointing in the direction of the rotor bottom. The gable-shaped end portion of the drive shaft can thus slide along the triangular plates, and the rotor is rotated to a defined, radial position in this way. Preferably, the drive shaft then has, below the gable-shaped end portion, two opposed parallel side faces and the parallel surfaces of the triangular plates in the interior of the shaft reception means abut on the parallel side faces of the drive shaft at the first, radially defined position of the rotor. 
         [0022]    The second locking element preferably includes a groove and is adapted to be manually moved to a position at which opposed inner surfaces of this groove abut on the side faces of the drive shaft. To this end, the second locking element is e.g. adapted to be pivoted about a pivot shaft within a reception means in the rotor. At a first open position of the radial locking element, the groove will then not act on the side faces of the drive shaft, but when the locking element is turned in the direction of the drive shaft, the groove will engage the drive shaft from above and then abut on the side faces of the drive shaft. 
         [0023]    The first locking element may have different structural designs and may be adapted to the geometry of the drive shaft in different ways, so that the latter can be axially locked. The locking element may e.g. engage a locking geometry in the drive shaft, when occupying the locking position. According to one embodiment of the invention, the first locking element is a metal sheet or safety metal sheet, which extends transversely to the drive shaft and engages a radial groove of the drive shaft, when occupying the locking position. The groove is preferably configured as a radial, circumferentially extending groove, so that the rotor, after having reached the second, axially defined position, can still be rotated about the drive shaft, when the second locking element is not locked. For locking the second locking element, it would only be necessary to manually return the rotor to a radial position, at which a positive locking engagement can be established between the groove of the radial locking element and the flat side faces of the drive shaft. 
         [0024]    The first locking element may, however, also have a different structural design and comprise e.g. one or a plurality of pins. Also friction-based locking elements may be used, provided that they comprise components that can be contacted and moved when the rotor is pushed onto the drive shaft. It would, however, also be possible to use systems in which the movement of the rotor on the drive shaft causes automatic unlocking and locking in some other way. Magnetic or electronic systems would here be imaginable. 
         [0025]    In order to be able to manually release the axial locking of the rotor, prior to pulling the rotor off the drive shaft e.g. after a therapy, the rotor may additionally include an operating element by means of which the first locking element can be moved manually from the locking position to the release position. According to one embodiment of the invention, the manual operating element is a lever that can be turned manually so as to release the locking. Also a push-button switch may be used, alternatively or additionally, as a manual operating element. 
         [0026]    The invention additionally comprises a medical device for extracorporeal blood treatment, comprising a tube roller pump including a pump housing having a curved running surface and a rotor that is rotatable within the running surface, a tube segment of an extracorporeal blood circuit being adapted to be placed between the running surface and the rotor. The tube roller pump is here configured according to an embodiment of the tube roller pump according to aspects of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The invention is best understood from the following detailed description when read in connection with the accompanying drawings. Included in the drawings are the following figures: 
           [0028]      FIG. 1  shows a schematic representation of a medical device for extracorporeal blood treatment with a blood pump; 
           [0029]      FIG. 2  shows a schematic top view of a tube roller pump having a tube segment and a rotor inserted therein; 
           [0030]      FIG. 3   a  shows a schematic side view of a rotor at the beginning of the operation of pushing the rotor onto the drive shaft of a tube roller pump; 
           [0031]      FIG. 3   b  shows a schematic top view of a rotor according to  FIG. 3   a;    
           [0032]      FIG. 4   a  shows a schematic side view of a rotor according to  FIG. 3   a  during unlocking of a first locking element; 
           [0033]      FIG. 4   b  shows a schematic top view of a rotor according to  FIG. 4   a;    
           [0034]      FIG. 5   a  shows a schematic side view of a rotor according to  FIG. 3   a  during locking of the first locking element; 
           [0035]      FIG. 5   b  shows a schematic side view of a rotor according to  FIG. 5   a;    
           [0036]      FIG. 6   a  shows a schematic side view of a rotor according to  FIG. 3   a  with a locked second locking element; and 
           [0037]      FIG. 6   b  shows a schematic top view of a rotor according to  FIG. 6   a.    
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]      FIG. 1  shows a schematic representation of the essential basic components of a medical device  19  for extracorporeal blood treatment including a blood pump, the blood pump being a tube roller pump, or a peristaltic pump. The tube roller pump includes a pump housing  10 , which is typically arranged on the front of the dialysis machine  19 . 
         [0039]    This tube roller pump has supplied thereto arterial blood  21  of a patient, which is then conveyed through the extracorporeal blood circuit. Subsequently, the blood is returned to the patient as venous blood  22 . In so doing, the blood is conveyed by means of the pump through a transfer system connected to a plurality of components of the dialysis machine, a tube segment  20  of the transfer system being inserted in the blood pump and a rotor  30  conveying the blood peristaltically through this tube segment  20 , as can be seen from an enlarged view according to  FIG. 2 . 
         [0040]    After having passed through the blood pump, the blood arrives at the dialyzer  15  after having preferably passed through an arterial air trap  13 . In the dialyzer  15  the blood is purified through an exchange of substances with a dialysate  16 , which is supplied to and discharged from the dialyzer  15 . After having passed through the dialyzer  15 , the blood arrives at a venous air trap  14  and is then returned to the patient. This circuit of the patient&#39;s blood is identified by arrows in  FIG. 1 . 
         [0041]    The setting of dialysis parameters and therapy monitoring can be executed via a display/input unit  17 , which is preferably configured as a touch screen. Furthermore, the dialysis machine  19  includes a control unit  18 . 
         [0042]      FIG. 2  shows a schematic representation of a top view of a tube roller pump having the tube segment  20  and the rotor  30  inserted therein. The tube roller pump is easily accessible for the operator of the machine, and the pump housing  10  is adapted to be covered by a lid, which is not shown and which is adapted to be pivoted e.g. upwards or to the side via a hinge so as to gain access to the tube segment  20 . 
         [0043]    The pump housing  10  has formed therein a curved running surface (bearing surface)  11 , which is defined by a recess in the housing and into which the tube segment  20  can be inserted in a loop shape such that the two tube ends project beyond the housing  10  at the bottom. The recess may be formed in the pump housing  10  with a lateral surface, which extends perpendicular to the front of the machine in a substantially uniform manner, or the running surface  11  is formed in a non-uniform manner by a lateral surface of the recess, which is concave in shape or even twisted in itself. 
         [0044]    The running surface  11  has arranged therein a rotor  30  having e.g. an approximately elliptical circumference so that, when rotating, it will be able to slightly compress the tube segment  20  at the main crowns  31 ,  32  by means of rollers, which are not shown. The clockwise rotation of the rotor  30  has the effect that also the area of a compressed tube segment moves clockwise until the associated main crown  31 , or rather the roller attached thereto, detaches itself from the tube segment. Meanwhile, the opposite main crown  32  has, however, moved into contact with the tube segment  20  once more, so that blood is conveyed peristaltically from the pump inlet to the pump outlet in the respective tube segment area ahead of the area in which the tube compressed by the rotor  30 . 
         [0045]      FIG. 3   a  shows a schematic representation of a rotor  30  at the beginning of mounting the rotor on a drive shaft  40  of a tube roller pump. The drive shaft  40  is located within the pump housing  10  in which the running surface  11  for accommodating the tube segment is formed. The drive shaft  40  of the pump is simultaneously the output shaft or transmission output shaft of a drive  12 , which is only indicated by a broken line in  FIG. 3   a.    
         [0046]    In the middle of the rotor  30  a shaft reception means  33  is provided, so that the rotor  30  can be pushed onto the drive shaft  40 . The shaft reception means  33  is substantially hollow-cylindrical in shape, but has a different geometry in certain areas thereof, e.g. triangular plate surfaces  35 ,  35 ′ on the inner surface of the shaft reception means  33 . For transmitting the torque from the drive shaft  40  to the rotor  30 , a (second) locking element or anti-rotation element or force transmitting element  60  is provided in the upper area of the rotor  30 , i.e. on the rotor side facing away from the drive  12 . This anti-rotation element  60  is supported within a reception means  34  in the rotor  30  such that it is pivotable about a shaft  61  so that it can be pivoted between a release and a locking position. The anti-rotation element  60  additionally includes a groove  62 , an end portion of the drive shaft  40  being in positive locking engagement with this groove  62  at the locking position. In addition, the anti-rotation element  60  may have provided thereon a crank handle  63  for manual emergency operation. In the situation shown in  FIG. 3   a , i.e. prior to the mounting of the rotor  30  on the drive shaft, the anti-rotation element  60  is pivoted to the left, i.e. outwards, and unlocked. However, the radial anti-rotation element  60  need not be open so as to allow the rotor  30  to be installed in the therapy or operating position, since, due to the geometries of the drive shaft  40  and the shaft reception means  33 , the rotor  30  is automatically guided to a specific relative rotary position, at which the upper end of the drive shaft  40  is in positive locking engagement with the groove  62  of the anti-rotation element  60 . 
         [0047]    In the area of the shaft reception means  33 , a (first) locking element  50  for axially fixing the rotor  30  on the drive shaft  40  is additionally arranged, said locking element  50  projecting radially inwards into the shaft reception means  33  in the locking position. This locking element  50  is mounted in a radially movable manner within a recess  36  in the rotor  30 , and is preferably spring-loaded and biased radially inwards by the force of a spring (which is not shown) and forced towards the shaft reception means  33 . In the interior of the drive shaft  40  e.g. a circumferentially extending groove  42  is provided, the locking element  50  engaging said groove  42  at the locking position so that the rotor  30  is axially locked in position on the drive shaft  40 . Locking may, however, also be accomplished by any other geometries of the drive shaft  40 , which are adapted to be brought into locking engagement with the locking element  50 . 
         [0048]    For inserting the rotor  30  into the pump, it can be grasped by an operator and pushed onto the drive shaft  40 , the anti-rotation element  60  being unlocked or pivoted out of the way in this condition. The geometries of the drive shaft  40  and of the shaft reception means  33  are configured and adapted to one another such that the rotor  30  is automatically guided to a first, defined rotary position relative to the drive shaft  40 . To this end, the end portion  41  of the drive shaft  40  facing the rotor  30  is wedge-shaped so that two oblique wedge surfaces are formed, which slope to the left and to the right in  FIG. 3   a . These oblique surfaces merge with two opposed, planar side faces or flat portions  43  and  43 ′ on the drive shaft  40 , which extend parallel to the axis of rotation of the drive shaft  40 . 
         [0049]    Additionally, two triangular plates  35  and  35 ′, tube inner surfaces extend parallel to the axis of rotation of the rotor  30 , are formed within the shaft reception means  33  on the inner wall thereof. In the representation according to  FIG. 3   a  only the rear plate  35  is shown. A second triangular plate  35 ′ extends parallel to the first plate  35  on the opposite side of the shaft reception means  33 , which is cut off in the view according to  FIG. 3   a . The plates  35  and  35 ′ define an isosceles triangle and are oriented such that the tip of the respective triangle points in the direction of the rotor bottom  37 . 
         [0050]    In the situation shown in  FIG. 3   a , the rotor  30  has been positioned by a user on the drive shaft  40  such that the tip of the wedge shaped end portion of the drive shaft  40  approximately meets the two tips of the triangular plates  35  and  35 ′. This can also be seen from the top view according to  FIG. 3   b , which shows the two opposed triangular plates  35  and  35 ′ within the shaft reception means  33 . The locking element  50  is (still) located above the plates  35 ,  35 ′, and the upper edge of the wedge-shaped front of the drive shaft  40  is oriented transversely to the inner surfaces of the plates  35 ,  35 ′. Furthermore, this view shows the planar side faces  43  and  43 ′ of the drive shaft  40 , which are also oriented transversely to the plates  35 ,  35 ′. 
         [0051]    Since in this position the outer sections of the wedge-shaped end portion  41  of the drive shaft  40  meet the tip of plate  35  and plate  35 ′, respectively, the rotor  30  cannot be attached to the drive shaft  40 . In response to slight rotation and pressure, the wedge surfaces of the wedge-shaped end portion  41  of the drive shaft  40  will, however, slide along the flanks or sides of the triangular plates  35 ,  35 ′, thus forcing the rotor  30  into a rotation, which will be discerned by the user, who can then follow this rotation with his hand. When, starting from the orientation shown in  FIG. 3   a  and  FIG. 3   b , the rotor  30  and the drive shaft  40  have been rotated relative to one another by 90°, they occupy the rotary position or orientation shown in  FIGS. 4   a  and  4   b , where the planar side faces  43  and  43 ′ of the drive shaft  40  now point to the front. Hence, they are oriented such that they extend parallel to the inner surfaces of the triangular plates  35  and  35 ′ (in  FIG. 4   a  behind the drive shaft). Furthermore, the wedge surfaces of the end portion  41  of the drive shaft  40  now slope to the front and to the back. 
         [0052]    This can also be seen from the top view according to  FIG. 4   b , where the side faces  43  and  43 ′ now abut on the inner surfaces of the plates  35  and  35 ′. The plates  35 ,  35 ′ and consequently also the side faces  43 ,  43 ′ of the drive shaft  40  are here preferably oriented parallel to the longitudinal axis of the rotor  30 . At the position shown in  FIGS. 4   a  and  4   b , the rotor  30  and the drive shaft occupy a first, defined rotary position relative to one another, but the rotor  30  is, in principle, prevented from being pushed further onto the drive shaft  40  because it is blocked by the locking element  50 . However, the rotor  30  and the oblique wedge surfaces in the end portion of the drive shaft  40  now have a defined orientation, in which the locking element  50  contacts one of the wedge surfaces and is able to radially displace this wedge surface outwards into the recess  36  against a spring force of the radially inwards biased locking element  50 , when the rotor  30  is advanced in the radial direction. This movement of the locking element  50  is illustrated in  FIGS. 4   a  and  4   b  by an arrow pointing to the left and to the lower left, respectively. In the course of this movement, the locking element  50  slides along the wedge-shaped end portion  41  of the drive shaft  40 , whereby the rotor  30  can be pushed further onto the drive shaft  40  until it finally arrives at a second, axially defined position, which is shown in  FIG. 5   a . Attention should in this respect, be paid to the fact that the recess  36 , in which the locking element  50  is radially guided, as can especially be seen in  FIG. 4   a , should be arranged in the defined, first relative rotary position of the drive shaft  40  such that it is located laterally of the edge of the wedge-shaped end portion  41 , that the locking element  50  should only come into contact with one of the wedge surfaces, but not with the wedge edge, and that it should be possible to guarantee that the locking element  50  can slide along the wedge surfaces. This can be accomplished in that, as shown in  FIG. 4   a , the recess  36  and the locking element  50  are located more on the side of one of the triangular plates  35 ,  35 ′ defining the orientation of the drive shaft  40  and consequently of the wedge surfaces. Furthermore, also the inward radial movement of the locking element  50  should be limited, e.g. by a stop (not shown), so as to prevent the locking element  50  from moving to a position in which it overlaps the wedge edge. 
         [0053]    At the axially defined position shown in  FIG. 5   a , the groove  42  of the drive shaft  40  is located in the area of the locking element  50 , so that the latter, acted upon by the force of the spring, will move into, and consequently engage the groove  42 . This movement of the locking element  50  is illustrated in  FIG. 5   a  by an arrow pointing to the right. The locking element  50  then abuts inside, i.e. from below on a side wall of the groove  42  and is no longer visible in the top view of  FIG. 5   b . The width of the groove  42  and the axial height of the triangular plates  35  and  35 ′ are chosen such that the tips of the plates  35  and  35 ′ come, at this position, into contact with the other (lower) side wall of the groove  42 , so that the rotor  30  can, on the one hand, no longer be pulled off the drive shaft and, on the other hand, no longer be pushed further onto the drive shaft  40 . The rotor  30  is thus secured against axial movements on the drive shaft  40 . Alternatively, the width of the groove  42  and the thickness of the locking element  50  can be adapted to one another such that the locking element  50 , in cooperation with the groove  42 , alone prevents an axial relative movement of the rotor  30  and of the drive shaft  40 . 
         [0054]    When the groove is a groove  42  that extends circumferentially in the radial direction, the rotor  30  can no longer be pulled off the drive shaft  40 , but it can be rotated on the drive shaft  40  until the radial anti-rotation element  60  is operated. This means that, at the position at which the anti-rotation element  60  is pivoted out of the way, i.e. to the side, axial locking is given, but the rotor  30  may be rotated making use of the crank handle  63 , e.g. for manual emergency operation. The patient&#39;s blood can thus be returned manually from the line system to the patient in an emergency operation, without any risk of the rotor  30  slipping off the drive shaft  40  while the crank handle is being operated. 
         [0055]    In order to accomplish also radial locking of the rotor  30  for a therapy, i.e. for the operating position of the rotor, the anti-rotation element  60  is pivoted about the shaft  61 , which extends perpendicular to and in spaced relationship with the axis of rotation of the rotor, onto the drive shaft  40 , as shown in the situation according to  FIG. 6   a . The inner surfaces of the groove  62  within the anti-rotation element  60  will then abut on the side faces  43  and  43 ′ of the drive shaft  40  in large area contact therewith, so that, due to the positive locking engagement, a relative rotation between the drive shaft  40  and the rotor  30  will no longer be possible and a torque can be transmitted from the drive shaft  40  to the rotor  30 . From  FIG. 6   a  it can additionally be seen that the crank handle  63  may simultaneously serve as a stop so as to limit the pivotal movement of the anti-rotation element  60  at the locking position. 
         [0056]    For demounting the rotor  30  after a therapy, the anti-rotation element  60  may again be pivoted away (in  FIG. 6   a  to the left) and thus be unlocked. This is, however, not absolutely necessary, but the anti-rotation means may also be released by simply pulling the rotor  30  off the drive shaft  40 . To this end, the axial locking element  50  must be released so that the rotor  30  can be pulled off the drive shaft  40 . The rotor  30  may have provided thereon a manual operating element for this purpose. This operating element may e.g. be a lever, which is turned for moving the locking element  50  against the force of the spring from the locking position radially outwards to the release position. After the removal of the rotor  30 , this lever may be turned once more, so that, before the rotor  30  is reattached to the drive shaft  40 , the locking element  50  will again occupy the locking position so as to allow the above described connection to be realized by executing only one handling step. The lever may, however, also be so conceived that, due to the force of the spring, it will automatically return to the position in which the locking element  50  occupies the locking position, as has already been described hereinbefore. 
         [0057]    However, the manual operating element may also be e.g. a push-button switch on the rotor  30 , which has to be pressed by an operator for pulling off the rotor  30 . Preferably, the switch is positioned such that it can be pressed while grasping the rotor  30 . When the switch is pressed, the locking element  50  is caused to move to the release position, but the locking element  50  will return automatically to the locking position, when the push-button switch is released. This can again be accomplished by the force of a spring. Alternatively, an additional push-button switch may be provided so as to cause the locking element  50  to move from the release position to the locking position. 
         [0058]    Furthermore, the radial anti-rotation element  60  may also have a structural design other than that of a pivotable component. It may, for example, be an insert, e.g. a slide, with a handle element, which is adapted to be moved to and fro within the recess  34  in the rotor  30  by the user. In this case, the insert has formed therein a groove, which, when the insert is correctly oriented with respect to the rotor and consequently the drive shaft, establishes the positive locking engagement with the drive shaft  40 , when the insert is forced into the rotor  30  or pushed onto the rotor  30 . For the purpose of unlocking, the insert has to be slightly pulled out or away from the rotor  30 . 
         [0059]    In comparison with this embodiment of an anti-rotation element, the above described variant is, however, advantageous insofar as a crank handle  63  for manual emergency operation can be integrated more easily in the anti-rotation element  60 , since in the case of a pivotable anti-rotation element  60  the crank handle  63  is moved away from the axis of rotation of the rotor  30  in the direction of the edge of the rotor  30 .