Abstract:
To increase the capacity of an extension attachment for a bulk material container comprising a frame ( 32 ) and a plurality of flaps ( 33, 34 ) linked to the frame ( 32 ), which are capable of swivelling and, in a swivelled-out position, surround an internal space ( 31 ) of the extension attachment, the internal surface ( 28 ) facing the internal space ( 31 ) of at least of one of the flaps ( 33 ) has a concave shape in the swivelled-out position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of priority to earlier filed German Patent Application 10 2007 003 653.3 filed in the German Patent Office on Jan. 18, 2007. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to an extension attachment for increasing the capacity of a bulk material container. In particular, it relates to a grain tank attachment for a combine harvester. 
       BACKGROUND OF THE INVENTION 
       [0003]    A grain tank of a combine harvester is frequently provided with an extension attachment that comprises several flaps pivotally linked to a frame to allow swiveling. Such a grain tank attachment is, for example, known from DE 10 2004 007 673 A1. When a combine harvester is travelling on the road, the flaps are swivelled inwards and lie flat on the opening of the grain tank so that the overall height of the combine harvester that is permissible on road traffic is not exceeded. During operation in the field, the flaps are in the swivelled-out position, in which they extend obliquely outwards and upwards from the frame. In this manner, they increase the volume of the grain tank, so that said tank can be emptied at longer intervals. 
         [0004]    In order to make the intervals between two emptying sequences as large as possible, it seems desirable at first sight to provide an attachment with flaps which are as large and as widely spread as possible. By doing so, however, the problem arises that the width of the flaps, i.e., their dimension transversely to the swivel axis, is limited by the width of the grain-tank opening, above which they must be laid one on top of the other in the closed position. Moreover, the centre of gravity of the combine harvester is increasingly shifted upwards when the extension attachment is filled with grain in the course of a harvesting process, so that the combine harvester&#39;s stability on sloped ground decreases. An extension attachment that extends too far up beyond the grain tank therefore impairs the operational safety of the combine harvester. 
       SUMMARY OF THE INVENTION 
       [0005]    Indeed, it would be possible to reduce the design height of an extension attachment, in a swivelled out state, by reducing the inclination of the flaps in the swivelled-out position, however, this would apparently occur at the expense of the carrying capacity. 
         [0006]    The object of the present invention is therefore to provide a collapsible extension attachment for a bulk material container, which combines a low design height with a large carrying capacity. 
         [0007]    This object is met according to the invention, in that an extension attachment for a bulk material container has a frame and a plurality of swivel-capable flaps, hinged on said frame, limiting a container extension volume, and in a swivelled-out position, the internal surface facing the container extension volume of at least one of the flaps has a concave shape. The concavity provides volumetric enlargement in comparison with a conventional extension attachment with straight and flat flaps in cross-section, without the dimensions of the extension attachment in the horizontal and vertical directions in the swivelled out condition having to be increased. 
         [0008]    The inclination of the internal surface of the flap in the swivelled-out position can be locally smaller than the angle of repose of the bulk material for which the container is provided. A particularly large volumetric increase is achievable when the internal surface of the flap is aligned locally horizontally in the swivelled-out position. 
         [0009]    In order to implement the concave shape on the one hand, in the swivelled-out state, and to be able to swivel in the flaps in a space-saving manner, it is appropriate for the flap to comprise segments that can be connected in a swivel-capable manner with one another. 
         [0010]    In particular, when the internal surface inclination of the flap is locally smaller than the angle of repose, then it is appropriate to provide auxiliary means that allow elimination of the bulk material from the flap of the bulk material container when the bulk material container is emptied. In the simplest case, it can involve conventional rotary actuators for the flap, which are powerful enough to swivel the flap inwards even if it is loaded with bulk material, so that said bulk material can slide inwards into the bulk material container. 
         [0011]    Another suitable auxiliary means can be a flexible membrane that is movable between a position that is adjacent to the internal surface of the flap and a raised position. By moving the membrane, if necessary repeatedly, the bulk material on it can be set in motion so that it slides into the bulk material container. 
         [0012]    The motion can be driven by a pulling means acting on the membrane, e.g. for tensioning the membrane. Alternatively, an interstice between the membrane and the internal surface of the flap can be exposed to pressurised gas in order for to raise the membrane off the flap. 
         [0013]    Furthermore, means for fluidizing the bulk material can be provided on the flap. As means for fluidization, for example, vibrators or knockers can be used; particularly, they can be driven pneumatically or electrically. 
         [0014]    According to a preferred embodiment, outlet openings for a pressurised gas are distributed on the internal surface of the flap. These outlet openings can entail a means of fluidization, or they can serve to pressurise the interstice between the flap and the membrane with gas. When a membrane is used, outlet openings for pressurised gas can be provided also in the membrane itself. 
         [0015]    As a further auxiliary means for eliminating the bulk material from the flap, at least one plate can be provided on the internal surface, which can be swivelled separately from the flap. 
     
    
     
       DRAWING FIGURES 
         [0016]    Further features and advantages of the invention ensue from the following description of exemplary embodiments with reference to the figures, as follows: 
           [0017]      FIG. 1  shows a combine harvester with an attachment for enlarging the volume of its grain tank according to the invention; 
           [0018]      FIG. 2  shows a perspective view of the extension attachment according to a first embodiment of the invention, in a swivelled-out position; 
           [0019]      FIG. 3  shows a perspective view of an extension attachment according to a second embodiment, in a swivelled-out position; 
           [0020]      FIG. 4  shows a perspective view of the extension attachment from  FIG. 3 , in a partially swivelled-in position; 
           [0021]      FIG. 5  shows a schematic half-section through the extension attachment that illustrates the principle of operation of the attachment; 
           [0022]      FIG. 6  shows a half-section analogous to  FIG. 5 , which shows a first variant of the means for removing bulk material from an extension attachment flap; 
           [0023]      FIG. 7  shows a schematic half-section that shows a second variant of the means for removing bulk material from the flap; 
           [0024]      FIG. 8  shows a half-section that shows a third variant of this means; 
           [0025]      FIG. 9  shows a half-section that shows a fourth variant of this means; 
           [0026]      FIG. 10  shows a half-section that shows a fifth variant of this means. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In  FIG. 1 , a schematic longitudinal section through a combine harvester  1  is depicted with an attachment  2  for enlarging the volume of a grain tank  3  according to the invention. The combine harvester is equipped with a cutting system  4  at the front, which is located near an inclined conveyor  5 . With the cutting system  4 , the combine harvester  1  takes the harvested plant  6  and feeds it to the inclined conveyor  5 . The inclined conveyor  5  transfers the harvested plant  6  to an upstream threshing system  7 . The threshing system  7  pre-pares the harvested plant  6 , wherein it is divided into a grain-chaff-mixture  8  and a product flow  9  comprising threshed stem. The grain-chaff mixture  8  is conveyed via a preparation rack  11  directly to a cleaning device  13 , which separates the grains  15  from non-grain components  16 , i.e. from stem and chaff parts. 
         [0028]    Behind the threshing system  7 , a turning drum  17  rotating in anti-clockwise direction is located, which conveys the product flow  9  comprising threshed stems onto a straw rack  18 . The straw rack  18  separates the grains  15  still inside the product flow  9 , short straw  21  and chaff  22 , which also reach the cleaning device  13  via a return-motion rack. The grains  15  separated by the cleaning device  13  are fed by a grain elevator  25  into a container  24  on the combine harvester, the so-called grain tank  3 . When necessary, the grains  15  are reloaded with a grain-tank emptying conveyor  29  from the grain tank  3  to a transport vehicle (not depicted). 
         [0029]    To minimise the frequency with which such reloading processes become necessary, the extension attachment  2  according to the invention is located on the upper side of the grain tank  3  in the form of a grain tank top attachment  27 . The grain tank top attachment  27  is depicted in a swivelled-out position in which it enlarges the volume of the grain tank  3 . 
         [0030]      FIG. 2  shows a perspective view of a first embodiment of the extension attachment  2  according to the invention. A rectangular frame  32  comprising four vertical walls of the extension attachment can be an integral component of the grain tank  3  or can be attached on a top edge of the grain tank  3  and be fixed on it, i.e., an internal space  31  surrounded by the extension attachment  2  in lateral direction is open upwards and joins the grain tank  3  at the bottom—not depicted in  FIG. 2 . At the top edge of each of the four walls of the frame  32  a flap  33 ,  33 ,  34 ,  34  is pivotally mounted. The flaps  34  are single-pieced, plane, rectangular or trapezoidal plates. The flaps  33  respectively consist of two segments connected pivotally with one another along a line  35 , namely an inner segment  36  which is approximately horizontal in the swivelled-out position, and an outer segment  37 . Since the two segments  36 ,  37  form an obtuse angle in cross-section on the line  35 , a concave internal surface  28  (see also  FIG. 5 ) of the flap  33  is achieved, through which the carrying capacity of the extension attachment  2  is made greater than the one of a conventional extension attachment with single-part, plane flaps. 
         [0031]    Four triangular plates  38  are respectively connected pivotally with one of the inner segments  36  and one of the flaps  34  by means of hinges. Further triangular plates  39  are respectively connected through a hinge with one of the outer segments  37  and have an edge that touches the adjacent plate  38 . To make the contact area between the plates  38 ,  39  grain tight, the plates  39  on their edge touching the plate  38  can be provided with a flexible lip, for example made of rubber that lies on the plate  38 . 
         [0032]    The flaps  34  have an inclination that is greater than the grain angle of repose, so that when the grain tank is emptied and the grain thereby drops from the extension attachment  2  through the opening of the frame  32  into the grain tank  3 , practically no grain remains on the flaps  34 . However, a substantial amount of grain remains on the essentially horizontal inner segments  36  of the flaps  33 . In order to move this rest grain into the grain tank  3 , too, the flaps  33 , as outlined by a dashed line in the schematic section of  FIG. 5 , are swivelled upwards and inwards about their inner edge  43  that joins them with the frame  32 . As soon as the slope of the flap segments  36 ,  37  is greater than the angle of repose a of the grain  15  still remaining on the flap  33 , the grain  15  slides completely into the grain tank. 
         [0033]    To prevent grain leaking sideways, the swivel motion of its two segments  36 ,  37  relative to one another and of the plates  39  against the outer segment  37  should be coordinated with the upwards swivel motion of the entire flap  33 , so that the lower edge of the plate  39  remains in contact with the plate  38 . This motion can make it necessary that the flaps  34  are swivelled beyond the position shown in  FIG. 2 , so that when their slope is smaller than the angle of repose, the grain that drops from the flaps  33  or from the triangular plates  38 ,  39  remain on them. To get rid of this grain completely, it can become necessary for the flaps  33 ,  34  to be swung back and forth several times. 
         [0034]    When the flaps  33 ,  34  are again free of grain and the combine harvester should again be made ready for road traffic, the plates  39  are swung against the outer segments  37 , as depicted by the dashed lines in  FIG. 2 . From the configuration resulting there from, the extension attachment  2  can be folded with the motion sequence disclosed in DE 10 2004 007 673 A1 (wherein the four plate-shaped attachment parts correspond to the flaps  34  described in this specification and the inner segments  36 ), so that the flaps  33 ,  34  come to rest spread flat and overlapping the frame  32  opening. 
         [0035]    A second embodiment of the extension attachment according to the invention with four concave flaps  33  in a swivelled-out state is shown in  FIG. 3 . The triangular plates  38  located at the corners of frame  32  are connected by means of hinges on two of their edges with inner segments  36  of the two respective neighbouring flaps  33 . Trapezoidal plates  40  respectively have an edge hinged with an outer segment  37 , and two edges that touch in a grain-tight manner one of the triangular plates  38  and an adjoining outer segment  37 , respectively. 
         [0036]    This extension attachment  2  is foldable via an intermediate stage depicted in  FIG. 4 . Two inner segments  36  opposite one another are swivelled upwards about their edge that is linked to the frame  32  and inwards to a position which is coplanar to the outer segment  37  of the same flap  33 . In this position, the trapezoidal plates  40  linked to the outer segments  37  are swivelled into a position outlined with dashed lines, in which they lie flat on the flaps  33  carrying them. When these flaps  33  are swivelled flat above the opening of the frame  32 , also the two other flaps  33  can be folded above the frame opening and be laid flat on top. 
         [0037]    To be able to free the flaps  33  of the extension attachment  2  quickly from the grain when emptying the grain tank  3 , diverse types of auxiliary means can be provided, of which some are explained in the following passage based on  FIGS. 6 to 10 . Like  FIG. 5 , each of these figures shows a half-section through the extension attachment  2  along a vertical cutting plane. According to the embodiment of  FIG. 6 , auxiliary plates  41 ,  42  are provided which lie flat on the segments  36 ,  37  of the flaps  33 , and of which the plate  41  can be swivelled about the inner edge  43  of the flap and the other plate  42  about its outer edge  44 . The auxiliary plates  41 ,  42  overlap slightly along the line  35 . When the lower auxiliary plate  41  is swivelled upwards, as shown in the figure, by means of dashed lines, it takes the outer plate  42  with it, and an amount of grain  15  remaining on the flap  33  when emptying the tank  3  starts to slide towards the tank  3 . Since the swivel motion of the auxiliary plates  41 ,  42 , is repeated several times if necessary, the grain  15  can be eliminated from the flap  33 . 
         [0038]    An effect that is similar to that of the auxiliary plates  41  may be attained with the help of a flexible membrane  45 , which, as shown in  FIG. 7 , is fixed along the edges  43 ,  44  on the flap  33  and lies loosely between the edges, so that a normally closed interstice  46  between it and the flap  35  may be exposed to pressurised air. If through compressed air supply to the interstice  46  the membrane  45  is lifted from the flap  33 , the grain  15  resting on the membrane  45  starts to slide and drops into the grain tank  3 . 
         [0039]    The membrane can be implemented in the form of a hose, of which one side is fastened, e.g., by adhesion, on the internal surface of the flap and another side can be lifted off the internal surface by supplying compressed air to it. 
         [0040]    In the embodiment of  FIG. 8 , compressed air lines  47  are routed through the flaps  33 , which discharge to outlet openings  48  on the inner side of the flaps  33 . Since compressed air is blown into the grain  15  resting on the flaps  33  through these openings  48 , the grain  15  is fluidised and flows reliably into the grain tank, even with minimum slope of the segment  36 . The concepts of  FIGS. 7 and 8  can be combined in that compressed air outlet openings are formed in the membrane  45 , to fluidize the grain that remains stuck on the membrane. 
         [0041]    In the variant of  FIG. 9 , also the internal surface of the flap  33  is covered with a flexible membrane  45  fixed at the edges  43 ,  44 . Instead of using compressed air, this membrane  45  can be lifted by means of pulling ropes  49  acting at different points of the internal surface of the flap  33 . When the pulling ropes  49  are successively tightened progressively from outside or from the top inwards or downwards, it is possible to free the flap  33  completely from grain, in one single passage. 
         [0042]    In addition, the embodiment of  FIG. 10  uses a membrane  45  lying on the internal surface of the flap  33  and fixed on the inner edge  43  of the flap. A pulling device  50  acts on an outer top edge of the membrane  45 . When the pulling device  50  tightens the membrane  45 , it assumes the shape depicted as dashes in  FIG. 10 , so that the grain  15  lying on the flap  33  slides into the tank  3 .