Abstract:
The subject matter of the invention is a device and a method for storing a traction chain, more specifically a self-bracing traction chain. Such a device and such a method for storing the traction chain so that it occupies very little space are provided by having the traction chain ( 10 ) wound into a plurality of side-by-side turns ( 14 ) about a winding apparatus ( 12 ) carried so as to be rotatable about its longitudinal axis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims Priority from German Application No. DE 20 2004 006 624.6 filed on 26 Apr. 2004  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method as set forth in the preamble of claim  1  and to a device as set forth in the preamble of claim  4 .  
         [0004]     2. Description of the Prior Art  
         [0005]     In systems for transporting persons or items, traction chains are often utilized to exactly and reliably move the actual transport platform from A to B. They may for example be lifts for persons or loads or feeding machines for feeding objects to processing plants or evacuating them therefrom, said processing plants being for example freeze drying facilities or coating furnaces. It is thereby known from the document DE 44 24 287 C2 or from EP 0 403 576 B1 to store the traction chains before, behind or beneath the actual drive wheel. Because, as a rule, such a traction chain can only be deviated in one direction, it is often stored beneath the drive wheel to form a half loop as can be seen from  FIG. 7  of DE 44 24 287 C2. However, storing the traction chain in this manner requires a large amount of space so that the entire system will be very large as a result thereof.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     In view thereof, it is the object of the present invention to provide a method and a device for storing a traction chain so that said traction chain occupies little space.  
         [0007]     As a technical solution to this object, the present invention proposes a method according to the features of claim  1  and a device according to the features of claim  4 . Advantageous developed implementations of this device and of this method are recited in the respective subordinate claims.  
         [0008]     A method implemented according to this technical teaching and a device configured according to this technical teaching have the advantage that the traction chain can be stored in the region located next to the actual drive wheel by winding it about a winding apparatus. Usually, in the transport systems of concern, there is space beside the drive wheel as the discrete transport platforms have a corresponding width. By winding the traction chain, space is made available before, beneath or below the actual drive wheel so that the transport system can be of an accordingly smaller construction, which affords significant savings in space. This permits to save much space in charging devices for freeze drying facilities for example so that the overall need for additional space to accommodate the charging device together with the freeze drying facility in the factory hall is reduced.  
         [0009]     It has been found out that it is advantageous to configure the traction chain so that it is slidable across the direction of movement. This makes it possible to displace adjacent chain links so that discrete chain links are offset by slightly more than the width of the traction chain after one whole turn about the winding apparatus so that the traction chain can be wound into a plurality of turns about the winding apparatus.  
         [0010]     In a preferred embodiment, the links of the traction chain are forced and guided by means of a restraint so as to become continuously offset. While the traction chain is wound about the winding apparatus, the links are caused to leave their aligned position and are offset by 1 mm to 5 mm, preferably by 3 mm, so that, after one turn, discrete chain links are offset by the width of the traction chain. When the traction chain is unwound from the winding apparatus, the discrete links are forced and guided by the restraint to be offset in the opposite direction so that the links, which had been offset by preferably 3 mm, are again aligned as soon as they leave the device for storing a traction chain. It is thus made certain that the traction chain forms one straight line while it engages the transport platform and that in the wound state the traction chain is oriented obliquely in order to achieve a plurality of turns about a winding apparatus.  
         [0011]     In a preferred embodiment, the winding drum is configured to be a cylindrical hollow drum on the surface of which the traction chain comes to rest. The advantage thereof is that a large surface is provided for the traction chain to rest against. Another advantage is that the traction chain can be wound uniformly about the cylindrical surface of the drum, thus avoiding wedging.  
         [0012]     In another preferred embodiment, the drum is mounted so as to be slidable across the direction of movement of the traction chain. The advantage thereof is that the drum can be caused to follow the movement while the traction chain is being wound and/or unwound in such a manner that the drum offers its free surface at every turn that is to be performed so that optimal winding of the traction chain may be achieved. It has thereby been found out that it is advantageous to guide the drum on a screw drive in order to achieve precise movement, thereby causing as little wear as possible to occur.  
         [0013]     In still another preferred embodiment, there are provided recesses on the drum surface. These recesses mainly serve to clean the entire device, more specifically in order to meet the hygiene standards required in the food and/or pharmaceutical industry.  
         [0014]     In another preferred embodiment, the links of the traction chain are slidable against each other on one side only. The advantage thereof is that the discrete links of the traction chain will not be inadvertently displaced in the wrong direction, which would result in incorrect winding. It has thereby been found advantageous to movably connect together adjacent links by means of a bolt, said bolt being guided by a pin provided on the first link and by a left and a right ridge provided on the second link. The left ridge is thereby configured to be thicker than the right ridge so that displacement is possible in one direction only.  
         [0015]     In still another preferred embodiment, an outwardly protruding driver member that is preferably made from a plastic material (PE or PVDF) is mounted to each link of the traction chain. Said driver member engages corresponding mating parts provided on the transport platform to cause the latter to be driven forward. Concurrently, said driver member engages a restraint that forces and guides the adjacent links of the traction chain so that they become offset across the direction of movement. It has thereby been found advantageous to manufacture the driver member from PE or from PVDF so as to produce as little friction as possible in the restraint which is also made from PE or PVDF.  
         [0016]     Further advantages of the method of the invention and of the device of the invention will become apparent in the appended drawings and in the following description of embodiments thereof. Likewise, the invention lies in each and every novel feature or combination of features mentioned above or described herein after. The embodiments discussed herein are merely exemplary in nature and are not intended to limit the scope of the invention in any manner. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0017]      FIG. 1  is a view of the device of the invention with the traction chain being almost completely wound up;  
         [0018]      FIG. 2  is a view of the device of  FIG. 1  with the traction chain being partially wound;  
         [0019]      FIG. 3  shows two links of the traction chain of  FIG. 1  in the offset position;  
         [0020]      FIG. 4  shows two links of the traction chain of  FIG. 1  in a rectilinear position;  
         [0021]      FIG. 5  is a perspective view of a restraint of the device of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     In the systems for transporting persons or goods from A to B, traction chains  10  are often utilized to drive the transport platform (which has not been illustrated in closer detail herein). The traction chain  10  is thereby stored in a device for storing said traction chain  10 . Said device includes a drum  12  about which the traction chain  10  is wound in a plurality of turns  14 . The traction chain  10 , which is composed of a plurality of links  16 , is solidly fixed at its last link to the drum so that the traction chain  10  is prevented from becoming displaced on the drum  12 .  
         [0023]     The device for storing the traction chain  10  further includes a drive wheel that has not been illustrated in closer detail herein and that is rotatably carried on a shaft  18 , as well as two retaining rods  20 ,  22 , a screw drive  24  and a restraint  26  that has been configured of two parts here.  
         [0024]     The drum  12  is carried on the screw drive  24  in such a manner that the drum  12  is movable pursuant to arrow  28  across the direction of movement of the traction chain  10 . The drum  12  further comprises a number of recesses  30  allowing for easy cleaning of the drum  12 .  
         [0025]     The  FIGS. 3 and 4  show two adjacent links  16 ′ and  16 ″. Said adjacent links  16 ′ and  16 ″ are articulated together by a bolt  32 . In the first link  16 ′ there is formed a right ridge  34  and a left ridge  36  in which the bolt  32  is retained, whereas a centrally disposed pin  38  through which the bolt  32  extends is integrally formed in the second link  16 ″. The left ridge  36  is thereby configured to be much wider than the right ridge  34  so that the pin  38  rests exactly against the left ridge  36  provided the adjacent links  16 ′ and  16 ″ are aligned as shown in  FIG. 4 . By contrast, the pin  38  rests against the narrower right ridge  34  provided the adjacent links  16 ′,  16 ″ are offset relative to each other as shown in  FIG. 3 .  
         [0026]     Reviewing now  FIG. 2 , imagine that the traction chain  10  is being wound about the drum  12 ; it is evident that the discrete links  16  of the traction chain  10  become offset with respect to their respective adjacent link  16  while resting against a first guiding edge  40 . The links  16  become offset relative to each other in such a manner that when the chain is wound one complete turn, they become offset by slightly more than the width of the traction chain  10  so that a plurality of turns  14  can be wound next to each other about the drum  12 . When the traction chain  10  is unwound from the drum  12 , the links  16  are guided along a second guiding edge  42  and offset in such a manner that, when they leave the restraint  26 , they are again aligned in a manner analogous to winding. It has thereby been found advantageous to manufacture the restraint  26 , more specifically the guiding edges  40 ,  42 , from PE in order to keep the frictional resistance low.  
         [0027]      FIG. 5  illustrates an alternative restraint  44  that also comprises a first and a second guiding edge  46 ,  48  and that is also disposed at such an incline that the discrete links  16  of the traction chain  10  become offset by exactly one width of the traction chain  10  as they are passed once through the restraint  44 . Since a number of links  16  are wound into one turn  14  about the drum  12 , an offset of between 1 mm and 5 mm, preferably of 3 mm, is sufficient when the adjacent links  16 ′,  16 ″ have a width of about 30 mm. The restraint  44  is thereby designed in such a manner that the distance between the first guiding edge  46  and the second guiding edge  48  is chosen to allow a driver member  50  mounted to the link  16  to be positively guided. It has been found advantageous to manufacture both the driver member  50  and the restraint  26 ,  44  from PE in order to achieve as little friction as possible there.  
         [0028]     It is understood that the exact dimensions of the discrete component parts are matched together. The offset between adjacent links  16  and, associated therewith, the restraint  26 ,  44 , are for example designed in such a manner that in one turn  14  a complete offset by slightly more than the width of the traction chain occurs. Also, the pitch of the screw drive  24  is chosen to allow correct winding and unwinding of the traction chain  10  onto and from the drum  12  to be achieved.  
         [0029]     In another embodiment that has not been illustrated herein, two devices for storing a traction chain of the type mentioned herein above are provided in one charging system, with the two drums being guided on the same screw drive.  
       Listing of Numerals  
       [0030]      10  traction chain  
         [0031]      12  drum  
         [0032]      14  turn  
         [0033]      16  link  
         [0034]      18  shaft  
         [0035]      20  retaining rod  
         [0036]      22  retaining rod  
         [0037]      24  screw drive  
         [0038]      26  restraint  
         [0039]      28  arrow  
         [0040]      30  recess  
         [0041]      32  bolt  
         [0042]      34  right ridge  
         [0043]      36  left ridge  
         [0044]      38  pin  
         [0045]      40  guiding edge  
         [0046]      42  guiding edge  
         [0047]      44  restraint  
         [0048]      46  guiding edge  
         [0049]      48  guiding edge  
         [0050]      50  driver member