Method and device for storing a traction chain

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 is occupies very little space are provided by having the traction chain (10) would into a plurality of side-by-side turns (14) about a winding apparatus (12) carried so as to be rotatable about its longitudinal axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims Priority from German Application No. DE 20 2004 006 624.6 filed on 26 Apr. 2004

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of storing a self-bracing traction chain.

2. Description of the Prior Art

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

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.

As a technical solution to this object, the present invention proposes a method of storing a self-bracing traction chain.

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.

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.

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.

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.

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.

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.

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.

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.

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.

DETAILED DESCRIPTION OF THE INVENTION

In the systems for transporting persons or goods from A to B, traction chains10are often utilized to drive the transport platform (which has not been illustrated in closer detail herein). The traction chain10is thereby stored in a device for storing said traction chain10. Said device includes a drum12about which the traction chain10is wound in a plurality of turns14. The traction chain10, which is composed of a plurality of links16, is solidly fixed at its last link to the drum so that the traction chain10is prevented from becoming displaced on the drum12.

The device for storing the traction chain10further includes a drive wheel that has not been illustrated in closer detail herein and that is rotatably carried on a shaft18, as well as two retaining rods20,22, a screw drive24and a restraint26that has been configured of two parts here.

The drum12is carried on the screw drive24in such a manner that the drum12is movable pursuant to arrow28across the direction of movement of the traction chain10. The drum12further comprises a number of recesses30allowing for easy cleaning of the drum12.

TheFIGS. 3 and 4show two adjacent links16′ and16″. Said adjacent links16′ and16″ are articulated together by a bolt32. In the first link16′ there is formed a right ridge34and a left ridge36in which the bolt32is retained, whereas a centrally disposed pin38through which the bolt32extends is integrally formed in the second link16″. The left ridge36is thereby configured to be much wider than the right ridge34so that the pin38rests exactly against the left ridge36provided the adjacent links16′ and16″ are aligned as shown inFIG. 4. By contrast, the pin38rests against the narrower right ridge34provided the adjacent links16′,16″ are offset relative to each other as shown inFIG. 3.

Reviewing nowFIG. 2, imagine that the traction chain10is being wound about the drum12; it is evident that the discrete links16of the traction chain10become offset with respect to their respective adjacent link16while resting against a first guiding edge40. The links16become 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 chain10so that a plurality of turns14can be wound next to each other about the drum12. When the traction chain10is unwound from the drum12, the links16are guided along a second guiding edge42and offset in such a manner that, when they leave the restraint26, they are again aligned in a manner analogous to winding. It has thereby been found advantageous to manufacture the restraint26, more specifically the guiding edges40,42, from PE in order to keep the frictional resistance low.

FIG. 5illustrates an alternative restraint44that also comprises a first and a second guiding edge46,48and that is also disposed at such an incline that the discrete links16of the traction chain10become offset by exactly one width of the traction chain10as they are passed once through the restraint44. Since a number of links16are wound into one turn14about the drum12, an offset of between 1 mm and 5 mm, preferably of 3 mm, is sufficient when the adjacent links16′,16″ have a width of about 30 mm. The restraint44is thereby designed in such a manner that the distance between the first guiding edge46and the second guiding edge48is chosen to allow a driver member50mounted to the link16to be positively guided. It has been found advantageous to manufacture both the driver member50and the restraint26,44from PE in order to achieve as little friction as possible there.

It is understood that the exact dimensions of the discrete component parts are matched together. The offset between adjacent links16and, associated therewith, the restraint26,44, are for example designed in such a manner that in one turn14a complete offset by slightly more than the width of the traction chain occurs. Also, the pitch of the screw drive24is chosen to allow correct winding and unwinding of the traction chain10onto and from the drum12to be achieved.

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.

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