Abstract:
The invention pertains to a sieve for a harvester thresher which consists of a frame and adjustable louvers that are mounted therein and can be adjusted by means of a motor-driven adjusting drive, wherein the sieve consists of at least two sieve elements that are arranged in the same plane and are respectively provided with a frame. In order to prevent the play of the adjusting drive and to adjust the louvers of the sieve elements independently of one another, the invention proposes to assign separate adjusting drives to the sieve elements.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
         [0001]    The invention pertains to a sieve for a harvester thresher which consists of a frame and adjustable louvers that are mounted therein and can be adjusted by means of a motor-driven adjusting drive. The sieve comprises at least two sieve elements that are arranged in a common plane and are respectively provided with a frame.  
           [0002]    Typically, in a harvester thresher, also known as a combine, after threshing and separation, some chaff and straw are still mixed with the grain. The cleaning unit removes this trash from the grain. In most combines, the cleaning unit comprises three major components: a cleaning fan, an upper sieve and a lower sieve. Sometimes the upper sieve is referred to as a chaffer. The upper and lower sieves are generally similar in construction, although the components may differ in size. The cleaning fan has its own housing, whereas the sieves are mounted to the cleaning shoe.  
           [0003]    The sieves are suspended on hangers attached to the sides of the cleaning shoe. The sieves are either adjustable or non-adjustable. The adjustable sieve is made up of a series of transversely extending louvers with rows of teeth. Each of these louvers is mounted on a crankshaft having a crank arm that engages an axially extending adjusting bar. By axially moving the adjusting bar, all of the louvers are moved simultaneously.  
           [0004]    It is known from DE 71 45 564 U, EP 1 068 792 A and EP 1 068 793 A to provide the frame of a sieve that forms part of the cleaning device of a harvester thresher with an electromotive adjusting drive in order to adjust the width of the sieve openings. In order to prevent the play created between the adjusting drive and the louvers of the sieve by intermediate transmission mechanisms in the form of Bowden cables or the like, the adjusting drive is arranged on the sieve frame.  
           [0005]    When adjusting the sieve in accordance with EP 1 068 792 A, two sieve elements of the upper sieve, which are arranged laterally and adjacent to one another, are adjusted by a common adjusting drive. A connecting rod or a threaded spindle is arranged for this purpose between the sieve elements and transmits the driving motion of the adjusting drive from one sieve element to the other sieve element.  
           [0006]    In this case, it is disadvantageous for the connecting rod or the threaded spindle to have a certain amount of play resulting from inaccurate adjustments of the louvers in at least one sieve element. In addition, the connecting rod must be detached and subsequently reattached when one of the sieve elements is removed for maintenance or repair purposes.  
           [0007]    The invention is based on the objective of additionally developing a sieve for a harvester thresher which is composed of several sieve elements in such a way that a more precise adjustment of the louvers can be achieved.  
           [0008]    In a sieve for a harvester thresher which is composed of two sieve elements that lie in the same plane, the invention proposes to assign a separate adjusting drive to each sieve element. If more than two sieve elements are provided, each of the sieve elements can be provided with a separate adjusting drive. However, it would also be conceivable to provide a first sieve element with a first adjusting drive, and to provide two or more additional sieve elements with a second, common adjusting drive.  
           [0009]    In this way, the sieve elements can be adjusted with less play (free travel and hysteresis) and even independently of each another. When removing the sieve elements from the cleaning shoe for reasons of maintenance, cleaning or repair, it is no longer necessary to separate and reconnect the drive connection between the adjusting device and the adjacent sieve element, which is time-consuming.  
           [0010]    The reduced surface of the louvers that is assigned to an adjusting drive makes it possible to use smaller and therefore less expensive adjusting drives. Due to their low weight, they can be directly mounted on or in the frame of the sieve element.  
           [0011]    The sieve elements are arranged in one plane and are usually situated laterally adjacent to one another relative to the forward driving direction of the harvester thresher. However, it would also be conceivable to arrange the sieve elements one behind the other. Sieves that are composed of multiple sieve elements may be considered for lower sieves as well as upper sieves.  
           [0012]    The adjusting drives may contain electric, hydraulic or pneumatic motors for generating a linear or rotational movement. The motors are provided with connecting elements for coupling to the power supply. The connecting elements are preferably automatically disconnected from connections that are arranged in and remain in the cleaning shoe when the sieve elements are removed, and automatically connected thereto when the sieve elements are installed. This significantly simplifies and accelerates the removal and installation of the sieve elements.  
           [0013]    A sieve according to the invention for a harvester thresher makes it possible to adjust the louvers of the sieve elements separately, as well as to realize different adjustments of the louvers of the sieve elements, by means of a corresponding manual or automatic control. Different adjustments make sense when the harvester thresher is used on hills, where it is advantageous to close the uphill sieve element further than the downhill sieve element. In this way, the air current generated by the cleaning blower is forced to flow more intensely through the downhill sieve in order better to penetrate the layer that is naturally thicker on the downhill side. A separation of undesirable non-grain constituents is simultaneously prevented in the thinner layer on the uphill sieve. This results in an improved efficiency of the harvester thresher on hills.  
           [0014]    According to another embodiment, the sieve elements may also be controlled as a function of the signals from sensors that are assigned to the sieve elements. Sensors of this type are able to sense the separation of grain or non-grain constituents underneath the sieve elements. Their signals are fed to a suitable control or regulating device that controls the adjusting drives of the sieve elements in such a way that separation and purity are optimized for each sieve element. This can be further simplified by utilizing more adjusting drives or separately adjustable sieve elements.  
           [0015]    Two embodiments of the invention are illustrated in the figures and described in greater detail below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a side view of an agricultural harvester thresher in which the threshing, separating and cleaning devices are shown;  
         [0017]    [0017]FIG. 2 is a top view of a first embodiment of the adjusting drives on the cleaning device;  
         [0018]    [0018]FIG. 3 is a top view of a second embodiment of the adjusting drives on the cleaning device, and  
         [0019]    [0019]FIG. 4 is a side view of the adjustment mechanism of the louvers. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    [0020]FIG. 1 shows a side view of a self-propelled agricultural harvester thresher  10 . The harvester thresher  10  contains a support structure  12  with wheels  14 . The support structure  12  consists of two axially extending side plates, between which the various processing devices for the material being harvested are arranged. A cutting mechanism  16  that conveys the material being harvested to a feederhouse  18  extends forward from the harvester thresher  10 . The feederhouse  18  contains a conveyor for conveying the harvested material to the threshing, separating and cleaning devices arranged between the side plates of the harvester thresher  10 . Although the present invention is described with reference to an axial flow harvester thresher, it may also be used on conventional harvester thresher configurations and other harvester thresher configurations with a cleaning shoe.  
         [0021]    In the harvester thresher  10  shown, the inclined conveyor  18  conveys the harvested material to a transversely extending guide drum  20  that feeds the material to an axial threshing and separating device  24  through an inlet transition region  22 . Grain and chaff are conveyed from the axial threshing and separating device  24  to a cleaning shoe  26 . The cleaning shoe  26  conveys the clean grain to a grain tank  28 , with the chaff being ejected on the rear side of the harvester thresher by the cleaning blower  30 . Harvested material which consists of neither grain nor chaff is conveyed by the axial threshing and separating device  24  to a transversely arranged guide drum  32  that ejects the material on the rear side of the harvester thresher  10 .  
         [0022]    Harvested material that is stored in the grain tank  28  can be unloaded by the operator by actuating an unloading conveyor screw  36  in the operator&#39;s cabin  34 . The threshing and separating device and the cleaning shoe are arranged between the side plates of the support structure  12 .  
         [0023]    In the harvester thresher  110  shown, an upper sieve  40  and a lower sieve  42  are arranged one above the another, where each sieve is composed of two sieve elements that lie adjacent to one another in the same plane. The sieves  40 ,  42  oscillate during the operation of the cleaning shoe  26  in such a way that the harvested material separated by the threshing and separating device  24  is received on the side of the sieves  40 ,  42  which faces the threshing and separating device  24  and is additionally conveyed opposite the driving direction of the harvester thresher  10 . In order to achieve an optimal cleaning effect of the cleaning shoe  26 , the rotational speed of the blower and the width of the openings in the sieves  40 ,  42  can be varied. According to the invention, two adjusting drives  74  and  76  are respectively assigned to each of the sieves  40  and  42  in order to adjust the width of the sieve openings.  
         [0024]    The upper sieve  40  and the lower sieve  42  are provided with transversely extending adjustable louvers  44 , which, as shown in FIGS. 2 and 3, are mounted in a rectangular frame  45  which is carried by the side walls of the cleaning shoe  38 . FIG. 4 indicates that each of the louvers  44  is equipped with a crankshaft  53  that contains a crank arm  51 . The crank arm  51  is arranged in a slot of an adjusting rail  49  that extends in the driving direction of the harvester thresher  10 . The adjusting rail  49  is arranged underneath a central crosspiece  47  of the frame  45  which is adjacent to an adjusting rod  52  and connected to and driven by said adjusting rod  52 . In this way, an axial movement of the adjusting rod  52  makes possible the angular adjustment of all louvers  44  of a sieve element  43 ,  43 ′ (see below) of the lower sieve  42  via the adjusting drive  76  as well as the angular adjustment of all louvers  44  of a sieve element of the upper sieve  40  via the adjusting drive  74 . The adjusting rod  52  extends through the frame  45  on the rear side of the cleaning shoe  38  and is supported so that it can be displaced in its longitudinal direction.  
         [0025]    [0025]FIG. 2 shows a lower sieve  42  that is equipped with a first embodiment of an adjusting drive  74  according to the invention. The lower sieve  42  is divided into two sieve elements  43 ,  43 ′ that are arranged adjacent to one another, where each is respectively provided with an assigned frame  45 , such that the sieve elements can be separately removed from the cleaning shoe  38  together with the respective adjusting drive  74 ,  74 ′ for maintenance and cleaning purposes. Each sieve element  43 ,  43 ′ is provided with a separate adjusting drive  74 ,  74 ′ for adjusting the width of the sieve openings. The components of the sieve element  43 ′ shown on the right are designated by the addition of an apostrophe after the reference numeral, whereas no apostrophe has been added to the reference numerals designating the components of the sieve element  43 ′ shown on the left. The sieve elements of the upper sieve  40  are also provided with respectively assigned drives  76 , although it would be conceivable to adjust both of these sieve elements with only one adjusting drive  76  if a corresponding lateral connection is provided.  
         [0026]    The width of the openings between the schematically illustrated louvers  44  can be adjusted by means of the adjusting rod  52  and a bell crank  80  that can be pivoted about a vertical axis. Electrically driven linear motors  84 ,  84 ′ that are coupled to the bell crank  80  are respectively mounted on consoles  88 ,  88 ′ connected to the frame  45 . The adjusting drive  74  shown in FIG. 2 is arranged on the frame  45  in such a way that the actuating direction extends approximately perpendicular to the oscillating direction S of the sieves. This provides the advantage that the sieve movement does not influence the rod  52  in the direction of the rod movement. The linear motor  84  is controlled via a flexible, multiwire electric line  86 . The width of the sieve openings which is sensed by a sensor arranged within the housing of the linear motor  84  is also fed back to the controller  100  and displayed to the operator in the driver&#39;s cabin, respectively, over this electric line. It is particularly preferred to connect the adjusting device directly to a data bus system arranged in the harvester thresher  10 . This makes it possible to reduce the number of wires in the line  86  and consequently the mass of the line oscillating therewith. The line  86  is coupled to the linear motor  84 ,  84 ′ by means of a plug connection  87  that is separated when the frame  45  is removed from the cleaning shoe  38 , leaving the electric line  86  in the cleaning shoe.  
         [0027]    [0027]FIG. 3 shows a lower sieve  42  that is equipped with a second embodiment of an adjusting drive  74 . The lower sieve  42  is composed of two sieve elements  43 ,  43 ′ that are also arranged laterally adjacent to one another. Components of the sieve element  43 ′ shown on the right are designated by the addition of an apostrophe to the reference numeral as in FIG. 2.  
         [0028]    Each of the sieve elements  43 ,  43 ′ contains an adjusting drive  74  in the form of an electric motor  90  that is mounted to the rear side of the frame  45  by means of a console-like holder  88 . The electric motor  90  contains a rotatable shaft  92  that drives a first gear  94 . The shaft  92  extends in the driving direction of the harvester thresher  10  which coincides with the oscillating direction S of the sieve. The first gear  94  cooperates with a second gear  98 , the rotational axis of which extends parallel to the shaft  92 . Internal threads that mesh with external threads arranged on the rear end of the adjusting rod  52  are formed at the center of the second gear  98 . Since the adjusting rod  52  is supported such that it is unable to turn and can only be displaced in its longitudinal direction, a rotation of the second gear  98  is converted into a displacement of the adjusting rod  52  by the internal threads and the external threads. The electric motor  90  may be conventionally provided with a sensor that senses the rotational speed of its shaft  92 . Alternatively, a stepper motor may be used. In both instances, the controller  100  that is electrically connected to the sensor and to the electric motor  90  is able to turn the electric motor  90  in such a way that the louvers  44  are moved into the desired position. The shaft  92  of the electric motor  90  extends in the oscillating direction S of the sieves. This provides the advantage that the sieve movement does not influence the rotor of the electric motor  90 .  
         [0029]    The controller  100  that is arranged in the operator&#39;s cabin  34  of the harvester thresher  10  and controls the adjusting drives  74 ,  74 ′ is not only connected to the sensors that sense the position of the louvers  44 , but also to various other sensors. An inclination sensor  102  senses the lateral inclination of the harvester thresher  10 , for example, with a plumb weight that drives a potentiometer. A separation sensor  104  that measures the quantity of grain passing through the sieve elements  43 ,  43 ′ is arranged underneath both sieve elements  43 ,  43 ′ of the lower sieve. Although only one sensor is shown in FIG. 1, FIGS. 2 and 3 show both of the sensors  104 .  
         [0030]    Based on the signal of the inclination sensor  102 , the controller  100  controls the adjusting drives  74 ,  74 ′ differently, such that, when using the harvester thresher  10  on a hill that is laterally inclined relative to the vertical, the uphill sieve element  43  or  43 ′ is closed further than the downhill sieve element.  
         [0031]    The sensors  104  and  104 ′ make it possible to sense the grain separation of the sieve elements  43 ,  43 ′. The controller  100  controls the adjusting drives  74 ,  74 ′ separately and, if so required, differently, in order to achieve an optimal separation with the sieve elements  43 ,  43 ′.