Abstract:
The electrically operated cartridge dispensing appliance includes dispensing rams and an electric motor actuating the thrust rods. Through a lever, the electric motor acts upon clamping members which actuate and move the thrust rods. The motor preferably acts upon a disk cam that actuates the lever. The construction of such a driving mechanism is both simple and cost-efficient and space-saving.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an electrically operated cartridge dispensing appliance including dispensing rams and an electric motor for actuating the thrust rods.  
       PRIOR ART  
       [0002]     Electrically operated dispensing appliances, particularly for dispensing two-component materials for dental impressions, are e.g. known from EP-A2-1 101 538, where an electric motor actuates lead screws to drive the thrust plates connected thereto and to dispense the two components. Another appliance is disclosed in EP-B-492 413, where a magnet clutch is used for uncoupling the feeding mechanism from a thrust slide that is pulled by chains. Both of the described driving mechanisms have in common that their construction is complicated and therefore expensive or relatively bulky.  
         [0003]     Furthermore, EP-B1-0 586 342 or DE-A-3 128 611 disclose an appliance for manual operation where the dispensing rams are actuated by a canted clamping lever. One aim of these embodiments is a most rational force transmission from an actuating lever turning around a fulcrum to linearly advanced rams.  
       SUMMARY OF THE INVENTION  
       [0004]     On the background of this prior art, the object of the present invention is to provide an electrically operated cartridge dispensing appliance whose mechanism for driving the dispensing rams is simple in construction and space-saving. This is accomplished by an appliance wherein the electric motor acts via a lever upon a clamping lever that actuates and moves the thrust rods. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     The invention will be explained in more detail hereinafter with reference to drawings of an exemplary embodiment.  
         [0006]      FIG. 1  shows a partly sectioned perspective view of the part of the dispensing appliance that is essential to the invention;  
         [0007]      FIG. 2  shows the appliance of  FIG. 1  in a longitudinal section;  
         [0008]      FIG. 3  shows a sectional view of an enlarged detail of the appliance of  FIG. 2  in the starting position;  
         [0009]      FIG. 4  shows a section according to line IV-IV in  FIG. 3 ;  
         [0010]      FIG. 5  shows a sectional view of an enlarged detail of the appliance in the clamping position;  
         [0011]      FIG. 6  shows a section according to line VI-VI in  FIG. 5 ;  
         [0012]      FIG. 7  shows a sectional view of an enlarged detail of the appliance at the end of the dispensing operation; and  
         [0013]      FIG. 8  shows a section according to line VIII-VIII in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]      FIG. 1  shows a part of the enclosure  1  of a bench-type appliance as mentioned in the introduction, the enclosure and the cartridge holder being known from the prior art.  FIG. 1  further shows one storage container of double cartridge  2  and a dynamic mixer  3  as described in EP-A2-1 106 243, for example. Through a driving mechanism that will be described below, an electric motor  4  actuates a double ram  5  having two thrust rods  6  and  7  and thrust plates  8 , thereby supplying the two components contained in the storage containers of the cartridge to the dynamic mixer where they are mixed. The two thrust rods  6  and  7  are connected to each other by a handle  9 .  
         [0015]     Electric motor  4  actuates a disk cam  10  turning about an axle  11  in the enclosure and essentially comprising two driving surfaces, i.e. a steep clamping ramp  12  and a dispensing surface  13 . The disk cam actuates a disk cam roller follower  14  that is fastened to a lever  15  hinged on a pivot  16  supported in the enclosure. Above the pivot, lever  15  is hinged via an axle  17  on a fork  18  of a cuboid driving block  20 , axle  17  running in an elongated hole  18 L. Driving block  20  is located in a U-shaped portion  19  of the enclosure, and thrust rods  6  and  7  are guided in respective bores in the U-shaped enclosure portion and in driving block  20 .  
         [0016]     As appears in  FIGS. 4, 6 , or  8 , each thrust rod is surrounded inside cuboid driving block  20  by the clamping portion  21 ,  22  of an inwardly extending clamping lever  23 ,  24 . A respective aligning pin  25 ,  26  for each clamping portion passes through driving block rear wall  31 , one end of which rests on rear wall  27 , with respect to the cartridges, of U-shaped enclosure portion  19 , and the other end of which rests on the clamping portion in the starting position in order to restore the non-clamping starting position of the latter after the return stroke. At the front end of the clamping portion, respective compression springs  28 ,  29  are recessed in front wall  30  of the driving block, which push the clamping portions towards the aligning pins. Opposite each clamping lever, respective canting pins  32 ,  33  are recessed in rear wall  31  of the driving block.  
         [0017]     The two clamping portions  21  and  22  do not fit the thrust rods exactly positively but their bores  34  are slightly larger than the diameter of the thrust rods, thereby allowing the clamping portions to be canted, as appears when comparing  FIGS. 4 and 6 .  
         [0018]     In the starting position according to  FIGS. 3 and 4 , a symbolically illustrated return spring  35  fastened to front wall  36  of U-shaped enclosure portion  19  pushes driving block  20  in the direction of wall  27 , thereby compressing compression springs  28 ,  29  through aligning pins  25 ,  26 . Clamping portion bores  34  are thus aligned parallel to the thrust rods, thereby allowing a manual actuation of the thrust rods. This arrangement ensures that the clamping levers are engaged as soon as driving block  20  moves in the dispensing direction. Instead of a compression spring between the enclosure and the driving block, a suitable spring arrangement may be provided on lever  15  for pushing the latter forward and thus the driving block backward.  
         [0019]     In the position of  FIGS. 7 and 8 , the disk cam has almost reached the end of the dispensing surface while the clamping portions are still in the clamping position. The driving block and thus the thrust rods have thus attained their full working stroke C″, see  FIG. 2 .  
         [0020]     By actuating a non-represented switch, the motor is started and the disk cam is set into rotation in the direction of the arrow. Starting from the position shown in  FIG. 3 , the steep clamping ramp  12  of the disk cam actuates disk cam follower roll  13  so that driving block  20  is moved forward in the direction of the cartridge by lever  15 . The clamping portions are thereby released and pushed toward the rear wall  31  of the driving block by the compression springs. Through the action of canting pins  32 ,  33  upon clamping levers  23 ,  24 , the clamping portions are canted and provide a fixed connection between driving block  20  and the thrust rods.  
         [0021]     In the position of  FIGS. 5 and 6 , the clamping portions are maximally canted, and the working stroke begins due to the action of the dispensing surface of the disk cam.  
         [0022]     In the position of  FIGS. 7 and 8  at the end of the dispensing surface, working stroke C″ is completed and the disk cam has reached the starting and rest position of  FIG. 3  after a rotation of 360°. Between the end of the dispensing surface and the beginning of the steep clamping ramp, return spring  35  pushes the driving block back to the starting position. Aligning pins  25 ,  26  align the clamping portions parallel to the thrust rods, thereby releasing them and allowing their manual retraction.  
         [0023]     In  FIG. 2  it is shown that during a rotation of 360°, the disk cam first imparts the thrust rods a clamping stroke C′ and then a maximum working stroke C″. However, the dispensing may also be stopped earlier, i.e. after a smaller working stroke. After each partial working stroke, the disk cam is turned back to the starting position where the thrust rods are released by aligning the clamping levers by means of the aligning pins. It is thus possible to retract the thrust rods manually and to remove the cartridge. The entire system stroke D, i.e. the complete dispensing of the cartridge content is achieved by repeated successive working strokes C″ or parts thereof.