Abstract:
A device for metering of powdery filling material is proposed, with a filling material container, on the bottom of which at least one metering opening is arranged, with at least one transfer plunger which can be introduced by a movement system into the metering opening in order to transfer the filling material located in the metering opening into a receptacle. In addition to the movement system, a drive unit is provided for applying a force to the transfer plunger in order to assist the transfer of the filling material into the receptacle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/058458 filed on Jul. 1, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is based on a device for metering a powdered product. 
     2. Description of the Prior Art 
     From German Patent Disclosure DE 102 11 118 A1, one such device is already known, which has a product container with bores embodied in its bottom. The bores cooperate with stuffing plungers and transfer plungers. A stuffing ring that serves as a counterholder to the stuffing plungers is disposed below the bottom. To avoid powder losses, it is provided that the product container is embodied axially movably, in such a way that during the downward motion of the stuffing plungers, the product container can be pressed against the stuffing ring. This is accomplished by means of holding-down elements that are movable synchronously with the stuffing plungers. 
     Particularly in transferring powder from sticky products, the powder compact can stick to the transfer plunger and thus not drop on its own into the bottom part of a capsule that is standing ready. In a known solution to this problem, the transfer plunger is kept in position, just above the segment of the bottom part, until such time as the capsule transporter carrying the circularly arranged bottom-part segments has moved onward by a certain angle. Since the upper edge of the bottom parts of the capsules is located at a lower level than the upper edge of the segment of the bottom part, the powder compacts become sheared off by the transfer plungers at the upper edge of the segments of the bottom part and then either drop into the bottom parts of the capsules or remain sticking to the edge of the bore in the segment of the bottom part. However, because the powder compacts break off unevenly, the result is imprecisions in dosage and dragging or soiling of the product as well as problems in closing the capsules. It is the object of the invention to overcome the aforementioned disadvantages. 
     ADVANTAGES AND SUMMARY OF THE INVENTION 
     The device according to the invention for metering a powdered product has the advantage over the prior art that the powder compacts can be knocked clean securely during the transfer operation. By means of the additional drive unit, such a strong force can be exerted on the transfer plungers that are in contact with the product that because of the spontaneous acceleration of the heavy transfer plungers on the one hand and the mass inertia of the very lightweight powder compacts (or product) on the other, a tearing force is exerted that is greater than the forces of adhesion operative until then between the transfer plunger and the powder compact. The powder compacts thus detached then travel in free fall, unhindered, along their further course downward back into the bottom part of the capsule. 
     In an expedient refinement, it is provided that the drive unit speeds up the transfer plunger counter to the transfer direction. A vehement impetus or impact can shoot the plunger suddenly upward during the fading downward motion, so that especially strong forces act on the plunger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One exemplary embodiment of the device according to the invention for metering a powdered product will be described in further detail below in conjunction with the drawings, in which: 
         FIG. 1  shows a perspective view of the metering device; 
         FIG. 2  is a sectional view through the additional drive unit; 
         FIG. 3  shows a further sectional view, rotated by 90° relative to  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The device  10  described thus far serves to meter the product into bottom parts  22  of the capsules that stand ready. To that end, the product container  12  is rotated in increments to beneath stuffing plungers  19 , or in the transfer position to beneath the transfer plungers  16 . During the stopped phase of the product container  12 , a product, such as powder or pellets, located in the region of the metering openings  14  is forced into the metering openings  14  by a downward motion of the stuffing plunger  19 . In the region of the transfer plungers  16  in which the metering openings  14  communicate with the bottom parts  22  of the capsules located beneath them, the powder compact is thrust by the transfer plunger  16  into the respective bottom part  22  of the capsule by a downward motion of the movement system  24 . Particularly with sticky products or from a static charge, powder compacts may still stick to the transfer plungers  16 . This is now prevented by the drive unit  27 , which is provided in addition to the movement system  24  and which by a knocking-off motion reinforces the dropping of the powder compacts from the transfer plungers  16 . At the end of the transfer stroke described, the transfer plungers  16  are slowed down by the braked downward motion. The drive unit  27 , for instance comprising the pneumatic cylinder  36  and the lifting tappet  38 , now comes into action. By means of the pneumatic cylinder  36 , the lifting tappet  38  is accelerated upward, counter to the transfer direction, and with full force strikes the underside of the yoke  34 . The yoke  34  is mechanically coupled via the shafts  32  to the connecting pins  44  to the transfer plunger holder  30 , so that the transfer plungers  16  jerk forcefully counter to the transfer direction. The transfer plunger holder  30  is connected rigidly to the tops of the transfer plungers  16  via the comb  18 . This vehement impetus accelerates the transfer plungers  16  suddenly upward during the fading downward motion. The spontaneous acceleration of the heavy transfer plungers  16  on the one hand and the mass inertia of the very lightweight powder compacts on the other bring about a tearing force that is greater than the forces of adhesion, operative until then, between the transfer plunger  16  and the powder compact. The thus-detached powder blank now traverses the further course downward unhindered, in free fall, into the bottom part  22  of the capsule that is standing ready. The transfer plunger holder  30  moved upward relative to the guide  28  is returned to the original outset position downward in the transfer direction. 
     In addition to the movement system  24 , the transfer plungers  16  can now be moved in the transfer direction relative to the transverse arm  26  by a drive unit  27 . One component of the drive unit  27  is a pneumatic cylinder  36 , with which via a countersunk screw  40  a lifting tappet  38  is connected. Upon activation of the pneumatic cylinder  36 , the lifting tappet  38  presses against the underside of a yoke  34  that completely covers the lifting tappet  38 . The yoke  34  is in turn, secured via respective screws  33  laterally to shafts  32  oriented in the transfer direction. The shafts  32  are in turn connected on their respective ends to a transfer plunger holder  30  via connecting pins  44 . A comb  18  is disposed in the transfer plunger holder  30  for securing the ends of the transfer plungers  16  to the transfer plunger holder  30 . The transfer plunger holder  30 , comb  18 , shafts  32 , yoke  34  and screws  33  form a unit whose parts are fixed relative to one another and which can move in a guide  28  relative to the transverse arm  26 , in or counter to the transfer direction. The guide  28  is solidly connected to the transverse arm  26  and its plunger guide  17  via a respective screw means  29 . 
     The shaft  32  penetrates the guide  28  via a suitable opening and protrudes past a recess  46  into the interior of the transfer plunger holder  30  so as to be solidly connected to it via the connecting pin  44 . In the region of the recess  46 , a spring  42  is disposed around each shaft  32  and is braced on its upper side relative to the guide  28  and on its underside relative to the upper side of the transfer plunger holder  30 . The spring  42  serves to return the unit, comprising the transfer plunger holder  30 , shafts  32 , screws  33 , and yoke  34 , to the original outset position, counter to the transfer direction, once a stroke has taken place. It can also be seen from  FIG. 1  that the transfer plunger holder  30  is guided substantially in cuplike fashion relative to the guide  28 . This prevents contamination of the transfer plunger holder  30  by the product. 
     The device  10  described thus far serves to meter the product into bottom parts  22  of the capsules that stand ready. To that end, the product container  12  is rotated in increments to beneath stuffing plungers, not shown, or in the transfer position to beneath the transfer plungers  16 . During the stopped phase of the product container  12 , a product, such as powder or pellets, located in the region of the metering openings  14  is forced into the metering openings  14  by a downward motion of the stuffing plunger, not shown. In the region of the transfer plungers  16  in which the metering openings  14  communicate with the bottom parts  22  of the capsules located beneath them, the powder compact is thrust by the transfer plunger  16  into the respective bottom part  22  of the capsule by a downward motion of the movement system  24 . Particularly with sticky products or from a static charge, powder compacts may still stick to the transfer plungers  16 . This is now prevented by the drive unit  27 , which is provided in addition to the movement system  24  and which by a knocking-off motion reinforces the dropping of the powder compacts from the transfer plungers  16 . At the end of the transfer stroke described, the transfer plungers  16  are slowed down by the braked downward motion. The drive unit  27 , for instance comprising the pneumatic cylinder  36  and the lifting tappet  38 , now comes into action. By means of the pneumatic cylinder  36 , the lifting tappet  38  is accelerated upward, counter to the transfer direction, and with full force strikes the underside of the yoke  34 . The yoke  34  is mechanically coupled via the shafts  32  to the connecting pins  44  to the transfer plunger holder  30 , so that the transfer plungers  16  jerk forcefully counter to the transfer direction. The transfer plunger holder  30  is connected rigidly to the tops of the transfer plungers  16  via the comb  18 . This vehement impetus accelerates the transfer plungers  16  suddenly upward during the fading downward motion. The spontaneous acceleration of the heavy transfer plungers  16  on the one hand and the mass inertia of the very lightweight powder compacts on the other bring about a tearing force that is greater than the forces of adhesion, operative until then, between the transfer plunger  16  and the powder compact. The thus-detached powder blank now traverses the further course downward unhindered, in free fall, into the bottom part  22  of the capsule that is standing ready. The transfer plunger holder  30  moved upward relative to the guide  28  is returned to the original outset position downward in the transfer direction. 
     The described device for metering a powdered product is suitable particularly for powder metering devices in the pharmaceutical field. However, it is not limited to that. Modifications with regard to the drive unit  27  are also possible without departing from the concept of the invention. What is essential is that a sufficiently strong force is exerted on the transfer plunger  16  that any product still adhering is acted upon by such a great force that it drops away from the underside of the transfer plunger  16 . This can be effected hydraulically, pneumatically or electrically, for instance by means of an electric drive mechanism, or by other suitable drive units. 
     The foregoing relates to the preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.