Abstract:
A conveyor device with an elastic load-bearing means guided between a drive and a return roller which are spaced apart parallel to and opposite one another, wherein the load-bearing means circulates endlessly in a carrying run and a lower run, is flexible in all directions and is configured to receive articles to be conveyed, and which can be driven in a conveying direction by drive trains disposed on longitudinal edges of the load-bearing means, characterised in that a support means for the carrying run is located between the carrying run and the lower run, wherein the drive trains are stretched to a greater extent than a region of the load-bearing means located between them.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. 119 to German Application No. 102013000372.5, filed 11 Jan. 2013, the entirety of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The invention relates to a conveyor means with a load-bearing means guided between two drive and return rollers which are spaced apart parallel to and opposite one another, wherein the load-bearing means circulates endlessly in a carrying run and a lower run, is flexible in all directions and is configured to receive articles to be conveyed, especially load items, and which can be driven in a conveying direction by means of drive trains disposed on longitudinal edges of the load-bearing means. 
     BACKGROUND 
     A conveyor means of this kind is known from EP 1 897 824 B1, for example, the load-bearing means there consisting of a chain conveyor which is flexible in its circulating direction and is rigid transversely thereto, in the manner of a plate conveyor. Since the load-bearing means formed by the chain conveyor is only flexible in one direction, however, but is rigid in the direction orthogonal thereto, in operation it is only possible for a one-dimensional curvature to form, so that in situations in which acceleration forces act on an item lying on the load-bearing means in a direction in which the load-bearing means is not curved, there is a risk that the item might slide off the load-bearing means. 
     SUMMARY 
     The invention sets out to solve the problem of advancing a conveyor means of the generic kind such that, while keeping the construction as simple as possible, a two-dimensional curvature and support for the flexible load-bearing means from below can be achieved, wherein the curvature corresponds to a trough-like deformation of the load-bearing means, so that there is no longer any risk that an item might unintentionally slide or roll laterally off the load-bearing means. 
     This problem is solved in accordance with the invention in a conveyor means of the generic kind by the step of locating a support means for the carrying run between the carrying run and the lower run. The support means can be given a concave shape when seen in the direction of the carrying run. 
     It may be contemplated that the support means is curved one-dimensionally and has a linear deepest region between and parallel to the drive and return rollers, especially centrally between them. A one-dimensional curvature of this kind means a curvature in a direction transverse to the axes of rotation of the drive and return rollers, or running in the conveying direction, whereas the support means runs in a straight line when seen transversely to the conveying direction. 
     Alternatively, it may be contemplated that the support means is curved two-dimensionally and in particular has a trough shape and a deepest region over a certain area or at a point between the drive and return rollers, especially centrally between them, and between the longitudinal edges of the load-bearing means, especially centrally between them. 
     It may be contemplated that the support means has one or two supporting region(s) adjacent to one or both drive and return roller(s) of the load-bearing means. 
     It is also possible that the support means has one or two supporting edge region(s) adjacent to one or both longitudinal edges of the load-bearing means. 
     It is possible that in the unloaded state, when not holding any articles to be conveyed, the load-bearing means does not touch the support means, or that in the unloaded state, some regions of the load-bearing means rest on the support means, wherein, apart from the biasing of the load-bearing means, the weight of the load-bearing means itself and the position of the support means relative to the drive and return rollers determined by the design and its distance from the unloaded load-bearing means (carrying run)—i.e. when it is only weighed down by its own weight—plays a role. 
     The drive trains may be formed solely by longitudinal edge portions of the load-bearing means—which may, for example, be belt-shaped—, each of which may have a width of, for example, 2%, 5%, 10%, 20% or 25% of a width of the load-bearing means, or alternatively by longitudinal edge portions in combination with members additionally fixed on longitudinal edges of the load-bearing means, such as V-belts or toothed belts. Members of this kind preferably possess greater elasticity than the load-bearing means, so that the elasticity of the longitudinal edge portions of the load-bearing means is only slightly reduced. The drive trains may have an elasticity that is the same as or less than the elasticity of the load-bearing means. The drive trains may be guided between the drive and return rollers with a predetermined or adjustable biasing force when the load-bearing means is in a state in which the only load to which it is subject is its own weight. 
     As explained, it is possible for the drive trains to be slightly less expandable than the load-bearing means, so that even in a loaded state, when an item is resting on the load-bearing means, they do not sag very much, whereas the load-bearing means, depending on the weight of the item, exhibits a distinct sag and may rest partially, largely or completely on the support means. It is convenient for a greatest sag of the load-bearing means (distance from an ideally load-free flat run between the return and drive rollers) at a lowest point of the load-bearing means between the drive trains to be greater than a greatest sag of the drive trains themselves, both in both the unloaded and loaded states. 
     The drive trains and the load-bearing means can preferably be stretched to different degrees. The drive trains are stretched to a greater extent than a region of the load-bearing means located between them in order to achieve a sufficient biasing force to transfer the drive forces required. In this case, the load-bearing means is driven with or without less stretch than the drive trains. Since the load-bearing means is stretched less than the drive trains, while having the same or greater elasticity compared to the elasticity of the drive trains, a trough in the load-bearing means in a central region between the drive trains is enabled to form simply under its own weight. Even in this unloaded state, the load-bearing means can still rest on the support means. Because of the additional load imposed by goods being conveyed, the sag of the load-bearing means is further increased, and the load-bearing means rests on the support means with at least a minimum weight of a load item when subjected to a load. 
     Support members may be disposed vertically adjacent to the longitudinal edges of the load-bearing means to support the drive trains, which may be spaced apart vertically from the drive trains in the unloaded state of the load-bearing means. These support members may be disposed at a slight distance from a position of the drive trains in the unloaded state in order to limit a sag of the drive trains to low amounts, such as to 1%, 2%, 3%, 4% or 5% of the distance of the axes of rotation of the drive and return rollers from one another. 
     A lower support means may be disposed beneath the lower run in order to limit the sag of the lower run or to eliminate it altogether, thus facilitating the formation of a sag or a concave or trough-like shape of the carrying run. 
     It is preferably contemplated that the drive trains are formed by V-belts or toothed belts fixed on the inside to the longitudinal edges of the load-bearing means. In particular, the invention also contemplates that the load-bearing means has a greater deflection radius on at least one of the drive and return rollers in the region of the drive trains than in a region located between them. 
     The invention further relates to a vehicle with a conveyor means in accordance with the invention, wherein a conveying direction of the conveyor means is transverse to a direction of travel of the vehicle. The vehicle may be configured, for example, as a car of a load item conveyor which is connected mechanically or by means of a suitable control to further vehicles of the same kind, such as in the form of a train-like arrangement in a conveyor for load items or a sorting conveyor. The vehicle or a car of this kind can be steered or rail-mounted. A vehicle of this kind can also be used in the context of a driverless transport system, especially with automatic control. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be explained by describing worked embodiments, reference being made to a drawing, in which 
         FIG. 1  shows a first embodiment, wherein  FIG. 1   a  shows a plan view,  FIG. 1   b  shows a side view,  FIG. 1   c  shows a section view K-K in  FIG. 1   a ,  FIG. 1   d  shows a section view A-A in  FIG. 1   b ,  FIG. 1   e  shows details from  FIG. 1   b ,  FIG. 1   f  shows details from  FIG. 1   d , and  FIGS. 1   g, h  show two perspective views, 
         FIG. 1   i  shows an enlarged excerpt from  FIG. 1   a , in which an edge and return region of the load-bearing means is illustrated in cross-section; 
         FIG. 2  shows a second embodiment, with  FIGS. 2   a - h  showing corresponding views to those in  FIG. 1 , 
         FIG. 3  shows a third embodiment, with  FIGS. 3   a - h  showing corresponding views to those in  FIG. 1 , 
         FIG. 4  shows a fourth embodiment, with  FIGS. 4   a - h  showing corresponding views to those in  FIGS. 1   a - h,    
         FIG. 5  shows the embodiment according to  FIG. 1  in an unloaded state, with  FIGS. 5   a - h  showing corresponding views to those in  FIGS. 1   a - h,    
         FIG. 6   a  shows a fifth embodiment, 
         FIGS. 6   b - d  show a sixth embodiment, and 
         FIG. 7  shows a seventh embodiment, with  FIGS. 7   a - h  showing corresponding views to those in  FIGS. 1   a - h.    
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a first embodiment of a conveyor means according to the invention in a plan view, various side and section views, and in two perspective views. The conveyor means consists substantially of two drive and return rollers  2 ,  4 , which are parallel to and face one another and are spaced apart, and which are rotatable about axes of rotation  2   a ,  4   a , and at least one of which (in this case the drive roller  4 ) is driven and is guided so as to circulate endlessly about the one load-bearing means in the form of a flexible conveyor belt  6 . 
     The conveyor belt  6  is provided on the inside, at each of its outer longitudinal edges  6   a ,  6   b  with a toothed belt  8   a ,  8   b , which is firmly joined to the conveyor belt, for example by bonding or vulcanising, and, together with the longitudinal edge portion to which it is joined, forms a drive train  8   a, b . The purpose of the drive trains is to transmit a driving force from the drive roller  4  to the conveyor belt  6 . 
     In the embodiment illustrated, there are disposed on the ends of the drive roller  4  sprockets  4   b  which engage with the toothed belt  8   a, b  in a positive fit ( FIG. 1   e ). The return roller  2  is smooth on the outside. The diameter of the return roller  2  at its lateral end portions in the region of the drive trains or the toothed belt can differ from the diameter of the middle portion of the return roller  2  and in particular can be greater. The same applies to the diameter of the sprockets, which can be greater than the middle portion of the drive roller  4  located between the sprockets. 
       FIG. 1   i  explains this with reference to an enlarged illustration of an end portion of the drive roller  4  with the sprocket  4   b . The drive roller  4  has a central shaft  5 , on the ends of which the sprockets  4   b  are non-rotatably mounted. Between the sprockets  4   b , a core  7  with an outer diameter d is rotatably mounted on the shaft  5 . The sprockets  4   b  and the circulating toothed belt  8   a, b  engaging with them are configured such that an outer reversing drum diameter D of the toothed belt  8   a, b  on the sprockets  4   b  is greater than  d . As a result, the longitudinal edges  6   a ,  6   b  of the conveyor belt are stretched more than the middle portion of the conveyor belt  6  located between them, which turns on the core  7 . The result of this in turn is that even when there is no load, a trough shape forms in the conveyor belt. 
     As explained, the middle portion of the conveyor belt, which is located between the toothed belt  8   a, b , is guided around the drive and return rollers  2 ,  4  with or without less bias than the longitudinal edges  8   a ,  6   b , which applies equally to a carrying run  10  and a lower run  12  of the conveyor belt  6 , as is illustrated in  FIGS. 1   c  and  1   f . In particular, it can clearly be seen that there is no or comparatively little sag in the toothed belt  8   a, b  and the longitudinal edges  6   a, b  associated with it, and that there is a comparatively great, trough-like sag in the portion of the conveyor belt  6  located between them, seen both in the conveying direction  13  to the adjacent return and drive rollers  2 ,  4  and looking towards the toothed belt  8   a, b.    
     In order to provide the conveyor belt  6  with defined support under load and to prevent excessive sag, a support means is disposed beneath the carrying run  10 , between the upper and lower runs  10 ,  12 , in the form of a sliding plate  14 , which is configured to be concave towards the carrying run  10 . The sliding plate  14  is curved one-dimensionally in the embodiment illustrated. It is flat when seen transversely to the conveying direction  13 , or in a direction parallel to the axes of rotation  2   a ,  4   a  of the return and drive rollers  2 ,  4 , and curved when seen in the conveying direction  13 .  FIG. 1   f  shows the straight shape of the sliding plate  14  in a direction transverse to the conveying direction  13 . 
     In  FIG. 5 , the shape of the conveyor belt  6  under the load imposed by a load item  16  resting on the conveyor belt is illustrated for the embodiment according to  FIG. 1 . As  FIG. 5   b  shows, even in this case of a load imposed, the longitudinal edges  6   a, b  with the toothed belt  8   a, b  of the conveyor belt  6  exhibit virtually no sag, whereas the conveyor belt  6  is pressed down in a middle portion, where the load item  16  is resting, as far as the sliding plate  14 , as  FIG. 5   d  also shows, in which a section in the region of an end face of the load item  16  is illustrated in a plane perpendicular to the conveying direction  13 . 
       FIG. 5   f  differs from  FIG. 1   f  in that it shows that the sag of the lower run  12  has been reduced because of the load weighing on the carrying run  10 , which can also be seen from  FIGS. 5   b, c  and  d.    
     Since a sag of the carrying run  10  can be lightened or increased by reducing or eliminating a sag of the lower run  12 , it can be advantageous to provide a lower support means to support the lower run in order in this way to limit or completely to eliminate a sag of the lower run.  FIG. 2  shows an embodiment similar to  FIG. 1 , in which a lower support means  20  is provided in the form of a sliding plate. Unlike the support means for the carrying run in the form of the sliding plate  14 , the lower support means  20  is not concave in shape, but flat. The resulting shape of the lower run  12 , portions of which rest on the lower support means  20 , is illustrated in  FIGS. 2   b, c  and  d  and, enlarged, in  FIG. 2   f.    
       FIG. 3  shows a variant in which the lower support means  20  is not formed by a sliding plate, but rather by one or more supporting rollers  22 , whose axes of rotation are parallel to those of the return and drive rollers  2 ,  4 . 
       FIG. 4  shows a variant in which the support means is formed in the shape of a troughed sliding plate  24  forming a two-dimensional concavity, having a middle portion  24   a  with a shape corresponding to the sliding plate  14  according to  FIG. 1 , which is curved one-dimensionally, with lateral portions  24   b  adjoining the middle portion  24   a  rising in a trough-like shape to the longitudinal edges  6   a, b  of the conveyor belt  6 , which may run to immediately beneath the toothed belt  8   a, b , as is illustrated in  FIGS. 4   d  and  4   f . In this embodiment too, a lower support means in accordance with  FIG. 2  or  3  may be provided. 
     The support means  14  may alternatively be formed by concave strips of rollers or concavely configured roller tracks. The same applies to the troughed sliding plate  24 , in which the middle portion and/or the lateral portions may be formed by strips of rollers or roller tracks. 
       FIG. 6   a  shows an embodiment in which a support means in the form of an intermediate plate  40 , regions of which are flat, prevents contact between the carrying run and the lower run and at the same time prevents excessive sag of the carrying run. The intermediate plate  40  forming the support means consists of a flat middle portion  40   a  and two portions  40   b ,  40   c  folded back away from it, which are likewise flat and extend as far as the return and drive rollers  2 ,  4 . The folded-back portions  40   b, c  extend from just below the carrying run to just above the lower run, where they pass over into the middle portion  40   a . Seen in the conveying direction  13 , the middle portion  40   a  is greater in length than the folded-back portions  40   b, c  and can occupy 50%, 60%, 70% or 80% of the distance between the axes of the return and drive rollers  2 ,  4 . 
       FIGS. 6   b, c  and  d  show a further embodiment, in which the support means is merely located in the vicinity of the drive and return rollers  2 ,  4  and corresponds in the example illustrated to the folded-back portions  40   b, c  of the embodiment according to  FIG. 6   a , without the middle portion  40   a . In this embodiment, the support means thus consists of two mutually opposing support parts  42 , which extend from the drive and return rollers  2 , 4  and are relatively short in length, seen in the conveying direction, for example 10%, 20% or 30% of a mutual distance between the axes of rotation of the drive and return rollers  2 ,  4  in each case. The support parts  42  extend from the drive or return roller from the carrying run to the lower run of the conveyor belt  6  in a downwardly inclining direction. 
       FIG. 7  shows an embodiment in which the load imposed on the load-bearing means, or the conveyor belt, is only supposed to be reduced in the region of the drive trains when a heavy load item is placed on the conveyor belt. For this purpose, the support means is not formed continuously transversely to the conveying direction  13 , but instead has supporting edge portions  32 ,  34  which are disposed beneath and spaced apart from the drive trains and are inclined transversely to the conveying direction, dropping towards the middle. When the conveyor belt is subjected to the load of a load item placed on it centrally, since the conveyor belt in its longitudinal edge portions and hence also the drive trains take on a transverse inclination, so that they slope towards each other, a large area of the drive trains tends to rest on the supporting edge portions  32 ,  34 , which have a similar transverse inclination, thus achieving a good supporting effect. 
     In the embodiment illustrated, the supporting edge portions  32 ,  34  are flat and are provided with lateral folds  32   a ,  34   a  as reinforcements. In other embodiments, the supporting edge portions could have a curvature when seen in the conveying direction, rather like the case with the sliding plate illustrated in  FIG. 1 , and/or a curvature seen transversely to the conveying direction. 
     LIST OF REFERENCE NUMERALS 
       2  return roller 
       2   a  axis of rotation 
       4  drive roller 
       4   a  axis of rotation 
       4   b  sprocket 
       5  shaft 
       6  conveyor belt (load-bearing means) 
       6   a, b  longitudinal edge 
       7  core 
       8   a, b  toothed belt (drive train) 
       10  carrying run 
       12  lower run 
       13  conveying direction 
       14  sliding plate (support means) 
       16  load item 
       20  lower support means 
       22  supporting roller 
       24  troughed sliding plate 
       24   a  middle portion 
       24   b  lateral portion 
       28 ,  30  supporting region 
       32 ,  34  supporting edge region 
       32   a ,  34   a  lateral fold 
       40  intermediate plate 
       40   a  middle portion 
       40   b ,  40   c  folded back portion 
       42  support part 
     d diameter (of  7 ) 
     D diameter (of  8   a, b  on  4   b ) 
     L axial length (of  2 ,  4 )