Abstract:
The invention concerns a grain tank for a combine harvester with a grain tank cover which can move between a closed and an opened position, closing off the grain tank at the top in the closed position, and in the open position expanding the useful volume of the grain tank upward. A rangefinder is proposed for detecting the fill level in the grain tank, which is arranged such that it is in a position above the maximum fill level of the fill material suitable for detecting the fill level of the fill material when the grain tank cover is opened, while when the grain tank cover is closed it is covered by the latter.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention concerns a grain tank for a combine harvester with a grain tank cover which can move between a closed and an opened position, closing off the grain tank at the top in the closed position, and in the open position expanding the useful volume of the grain tank upward.  
       BACKGROUND OF THE INVENTION  
       [0002]     Combine harvesters are machines which move across a field to harvest and thresh the grains planted there and to separate the kernel from the rest of the harvested material. The cleaned grain is kept for the time being in a grain tank, and when the tank is full enough the grain is transferred to a transport vehicle. The operator or the controls provided for this purpose require information as to the fill level of the grain tank, so that when the tank is full they can send the proper signals to have the transport vehicle come up to the combine harvester and take on the grain. Furthermore, the fill level of the grain tank can be used to measure or chart the yield.  
         [0003]     U.S. Pat. No. 5,282,389 A and WO 00/35265 A each propose detecting the fill level of the grain tank of a combine harvester by means of an ultrasound sensor. Details as to the mounting of the ultrasound sensor have not been disclosed.  
         [0004]     U.S. Pat. No. 5,957,773 A describes an experimental combine harvester in which the cleaned grain is taken to a test container. The fill level of the grain is detected by an ultrasound sensor rigidly arranged at the top end, approximately in the middle of the test container.  
         [0005]     DE 100 51 096 A describes a combine harvester with a closable grain tank cover for enlarging the volume of the grain tank.  
       SUMMARY OF THE INVENTION  
       [0006]     The underlying problem of the invention is considered to be the provision of a suitable mounting for an ultrasound sensor in a grain tank in order to detect the fill level.  
         [0007]     This problem is solved by the invention through the teaching of claim  1 , while the additional patent claims present features which further develop the solution in an advantageous manner.  
         [0008]     A grain tank for a self-propelled combine harvester has a grain tank cover which can move between a closed position and an opened position. A noncontact-type distance-measuring device serves to detect the fill level of the grain tank. It is coupled to the grain tank cover in such a way that it is covered on top by the grain tank cover and protected against the environment when the grain tank cover is in the closed position. If the grain tank cover is in the opened position, in which it enlarges the grain tank in the upward direction, the rangefinder finds itself in a position above the maximum fill level, so that it can even detect the fill level of the grain tank when not only the grain tank, but also the volume enlarged by the grain tank cover, is being used for filling purposes.  
         [0009]     The rangefinder preferably works with electromagnetic waves, such as radio waves (radar) or light (laser), and it is possible to use interferometer techniques. As an alternative or in addition to this, acoustic waves such as ultrasound are beamed out by the rangefinder and waves reflected from the surface of the fill are received. The rangefinder uses the travel time and/or the intensity of the waves reflected by the fill to determine the distance between it and the surface of the fill. In the case of using acoustic waves for the distance measurement, the current ambient temperature can be detected and taken into account to improve the measurement accuracy. From the distance thus determined, a suitable computer device can deduce and display and/or save in memory the fill level (height of fill and/or volume of fill). Already known techniques (see DE 38 12 2893 C, whose disclosure is incorporated in the present documents by reference) can be used to diminish measurement errors due to moving fill material that is dumped from a filling device into the grain tank and reflects waves toward the rangefinder. It would also be conceivable to compensate for reflections by the geometry of the grain tank by using a suitable evaluation, possibly one dependent on the fill level.  
         [0010]     Various possibilities exist for the arrangement of the rangefinder. In a first embodiment, a filling device (generally a filling screw) protruding into the grain tank can move between an extended position and a retracted position, and it supports the rangefinder. The filling device generally moves in synchronization with the grain tank cover, so that the filling device is in the retracted (extended) position when the grain tank cover is in the closed (opened) position. Preferably, the actuator used to move the filling device is also used to move the grain tank cover. But it is also conceivable to have separate actuators for the filling device and for the grain tank cover.  
         [0011]     In another embodiment, the rangefinder is fastened on the grain tank cover and moves along with it between the closed and the opened positions, generally performing a pivoting motion in this process. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The drawings show three sample embodiments, described more closely hereinafter. They show:  
         [0013]      FIG. 1 , a schematic view of a combine harvester with a grain tank and a grain tank cover,  
         [0014]      FIG. 2 , an oblique view of the grain tank cover in its opened position,  
         [0015]      FIG. 3 , an oblique view of the grain tank cover in its closed position,  
         [0016]      FIG. 4 , a partial section of the grain tank and the opened grain tank cover with a first embodiment of a measuring device for detecting the fill level,  
         [0017]      FIG. 5 , the view from  FIG. 4  with closed grain tank cover,  
         [0018]      FIG. 6 , a partial section of the grain tank and the opened grain tank cover with a second embodiment of a measuring device for detecting the fill level,  
         [0019]      FIG. 7 , the view from  FIG. 6  with closed grain tank cover,  
         [0020]      FIG. 8 , a partial section of the grain tank and the opened grain tank cover with a third embodiment of a measuring device for detecting the fill level. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]      FIG. 1  shows a farming combine  10  with a chassis  12  and running wheels  14  extending from it. A crop-retrieval device  16  is used to scoop up the crops and feed them to an inclined conveyor  18 . The crops are fed from the inclined conveyor  18  to a guide drum  20 . The guide drum  20  takes the crops upward through an intake transition zone  22  to an axial separating device  24 . Although the invention is described in connection with an axial-type combine harvester, it can also be used on other types of harvesters, such as conventional straw shaker combines or hybrid combines with a threshing drum connected to a rotor separating device. The directions indicated below, such as forward, backward, upward and downward, relative to the direction of forward movement of the combine  10 .  
         [0022]     The crops are threshed and separated in the axial separating device  24 . In this process, grain is removed from the harvested crop mat and drops down, along with unthreshed ears of grain, chaff, and other harvest material, through the threshing basket and the grill arranged underneath the axial separating device  24 , into a cleaning system  34 . Larger harvesting residues are ejected through an exit drum  30  at the back of the axial separating device  24 .  
         [0023]     The cleaning system  34  is outfitted with a blower, which blows out chaff to the rear of the combine  10 . The heavier clean grain is taken by a screw conveyor for clean grain, mounted transversely, to paddle elevator  36  for clean grain. The paddle elevator  36  takes the grain upward to a transitional housing  38 , in which the grain is fed to a conveyor screw  40  for loading a grain tank  42  with clean grain. When a sufficient fill level is attained, the grain is removed from the grain tank  42  by an unloading screw conveyor  44 . The operation of the combine  10  is controlled from an operator&#39;s cabin  48 .  
         [0024]     A grain tank cover  50  is arranged on top of the grain tank  42 , which is open at the top. In  FIGS. 1, 2 ,  4 ,  6  and  8  the grain tank cover  50  is shown in its opened position, i.e., its operating position, while in  FIGS. 3, 5  and  7  it is in its closed position.  
         [0025]     The grain tank cover  50  comprises a front wall  52  in the direction of forward travel of the combine  10 , which is made from rigid material, from sheet metal with reinforced lengthwise and transverse ribs  54  in the embodiment depicted. The grain tank cover  50 , furthermore, has a rear wall  56 , which is identical to the front wall  52 . On either side of the combine  10 , the grain tank cover  50  is provided with side walls  58  and  60  of flexible material, e.g., rubberized fabric. The side walls  58 ,  60  are joined at their side edges to the front wall  52  and the rear wall  56  and at their lower edge to the wall of the grain tank  42 . The front wall  52  and rear wall  56  are fastened to the walls of the grain tank  42  and can pivot at their lower ends about horizontal axes running transverse to the direction of travel of the combine  10 . The front wall  52 , rear wall  56  and side walls  58 ,  60  thus form a funnel-shaped, ring-like and upwardly open container in the operating position.  
         [0026]     On the outer surfaces of the side walls  58 ,  60  of flexible material is arranged a support element  62  in the form of a downwardly open arch with a central, vertical strut (the support element associated with the left side wall  60  is not visible in  FIG. 2 ). The support elements  62  are joined by cable  64  lying against the outer surfaces of the side walls  58 ,  60  to the upper corners of the front wall  52  and the rear wall  56 . The support elements  62  are hinged at their lower ends to the wall of the grain tank  42  so they can pivot about horizontal axes running parallel to the direction of travel of the combine  10 . They can swivel upward in order to buttress the side walls  58 ,  60 , but only through a maximum of 90 degrees, and no further.  
         [0027]     A grain tank filling device in the form of a filling pipe  66 , containing the conveying screw  40 , is arranged inside the grain tank  42  and transports the threshed material from the cleaning system  34  to the grain tank  42 . The filling pipe  66  can swivel by a drive mechanism  68 , comprising a hydraulic or electric motor, between an extended position as shown in  FIG. 2 , in which the filling pipe  66  extends upward at an angle of around 45 degrees, and a retracted position, in which the filling pipe  66  is dropped down into the interior of the grain tank  42  and only extends upward by about  20  degrees. In the extended position, the outlet opening at the upper end of the filling pipe  66  is arranged inside the ring formed by the side walls  52 ,  56 ,  58 , and  60  of the grain tank cover  50 . Thus, the grain tank cover  50  can be filled up to the top edge with grain.  
         [0028]     The filling pipe  66  is joined to each of the front wall  52  and rear wall  56  by a connecting rod element  70 , which transmits pushing and pulling forces. The connection element  70  is linked by suitable hinges to the filling pipe  66  and to each wall  52 ,  56 . When the filling pipe  66  is moved by the drive mechanism  68  from the extended position as shown in  FIG. 2  to the retracted position, the connection elements  70  make sure that the front wall  52  and the rear wall  56  pivot toward the inside of the grain tank  42 . Due to the cables  64  joined to the front wall  52  and rear wall  56  now being slack, the support elements  62  are folded inward, assisted by cables  72  stretched between each side wall  58 ,  60  and the filling pipe  66 . In this way, the side walls  58 ,  60  are folded inward. The cables  72  are joined to the support elements  62  and brace them and the side walls  58 ,  60  in the operating position, which is of special benefit when the grain tank cover  50  is full.  
         [0029]     As shown by  FIG. 3 , the front wall  52  and the rear wall  56  in the closed position form a closed lid for the grain tank  42 , protecting it and the side walls  58 ,  60  from environmental influences.  
         [0030]     The grain tank cover  50  is placed in the extended position in similar manner. The filling pipe  66  is lifted by the drive mechanism  68 , so that the connection elements  70  swing the front wall  52  and the rear wall  56  up by about 120 degrees, until the cables  64  are taut. Thanks to the stretched cables  64 , the support elements  62  are pivoted outward by about 90 degrees into the operating position. The cables  64  also restrict the pivot travel of the support elements  62 . The side walls  58 ,  60  are joined by suitable fastening means to the support elements  62 , so that they also go into the operating position.  
         [0031]     It should be noted that the grain tank cover  50  could also be rotated 90 degrees relative to the embodiment depicted, i.e., with the flexible side walls  58 ,  60  extending across the direction of travel. Nor do the side walls  58 ,  60  need to be made of flexible material, but instead could be made of rigid material, such as sheet metal (see DE 40 16 319 C, DE 44 45 933 A).  
         [0032]      FIG. 4  shows the grain tank  42  and the opened grain tank cover  50  in a partial cross section, viewed from behind. At the top end of the filling pipe  66  is fastened a rigid support  74  which rigidly supports a rangefinder  76 . When in operation, the rangefinder  76  beams ultrasonic waves onto the surface of the material (grain) contained in the grain tank  42  and in the grain tank cover  50  and receives the waves reflected from the surface. By using the travel time and/or intensity of the reflected waves, a computer device (not shown) determines the fill level of the grain tank  42  and indicates this optically or acoustically to the operator in the cabin  48  via an output device. To transmit the data concerning the fill level to a display device in the cabin  48 , one can use a data transmission bus (CAN). In addition, or as an alternative, it would also be conceivable to send a signal to the operator when reaching a predetermined fill level, to be used to actuate a signal light  80  and/or transmit wirelessly to a transport vehicle. The fill level or a quantity derived from it, such as the fill volume or (if the density of the harvested crop is known) the mass of the harvest material can also be georeferenced and saved in memory for purposes of precision agriculture, for which a satellite antenna  82  should be provided to receive signals from a global positioning system.  
         [0033]     When the filling pipe  66  is placed in the retracted position, as shown in  FIG. 5 , the support  74  with the rangefinder  76  also goes inside the grain tank  42 , where it is protected by the walls  52 ,  56 ,  68  and  60  of the grain tank lid  50 , which are brought into the closed position along with the filling pipe  66 .  
         [0034]     A second embodiment of the mounting of the rangefinder  76  is depicted in  FIGS. 6 and 7 , where the support  74  is joined rigidly to the wall  58 , preferably to the top of the support element  62 . The support  74  could also be joined to one of the rigid walls  52  or  56 . The rangefinder  76  interacts with the forward region of the pile of grain  78 , and when the grain tank cover  50  is in the closed position it lies in front of or behind the filling pipe  66  in the direction of travel.  
         [0035]     The embodiment of  FIG. 8  differs from that shown in  FIGS. 6 and 7  merely in that the rangefinder  76  interacts with the center of the pile of grain  78 . In this embodiment, the actual height of fill can be found by triangulation.  
         [0036]     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.