Abstract:
A harvesting machine includes a measuring device for capturing the throughput of collected and/or processed crops. The measuring device having a measuring surface which acts together with the crop material and is supported movably at a support point in such a manner that its position depends on the throughput of the crop material, and an optical position capturing device for capturing the position of the measuring surface. Preferably the support is a solid body articulation (42) and the position capturing device is a laser interferometer.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention concerns a harvesting machine with a measuring device for capturing the throughput of collected and/or processed crops, with the measuring device including a measuring surface which acts together with the crop material and is supported movably at a support point in such a manner that its position depends on the throughput of the crop material, and an optical position capturing device for capturing the position of the measuring surface.  
       BACKGROUND OF THE INVENTION  
       [0002]     Various different types of sensors are known for use in determining the yield in harvesters. Examples are baffles or rotating star feeders at the outlet of the grain elevator of a combine as disclosed in EP 0 208 025 A and U.S. Pat. No. 6,584,424B or baffles inside the delivery channel of a field chopper as disclosed in EP 0 887 008 A, weight sensors for capturing the weight acting on crop material carrying surfaces as disclosed in U.S. Pat. No. 4,407,380A, U.S. Pat. No. 5,318,475A, U.S. Pat. No. 5,959,257A, U.S. Pat. No. 6,066,809, and U.S. Pat. No. 6,313,414B, sensors for capturing the distance of prepress rollers as disclosed in DE 195 24 752 A, light barriers inside the combine elevator as disclosed in EP 0856 723 A, or radiometric absorption measurements at the elevator outlet as disclosed in WO 85/00087 A. In the case of mechanical sensors the crop material moves along a surface or strikes it, which generates forces, pulses or torque which can be transduced into electrical signals by potentiometers or according to EP 0 856 723 A by extensometers or optical displacement sensors. In DD 267 650 A a piezoelectric crystal is used for transforming the weight of the crop material acting upon it into an electrical signal.  
         [0003]     By means of a speed measurement of the material the material throughput per time unit can then be determined. If the density of the crop material is known, the volumetric throughput can then be deducted.  
         [0004]     The sensors mentioned have the disadvantage that additional elements need to be integrated into the harvester. Also, their accuracy and reliability is not always adequate in the highly dust and vibration impacted environment of a harvester.  
       SUMMARY OF THE INVENTION  
       [0005]     The objective on which the invention is based is considered to be: to demonstrate a measuring device for capturing the throughput in a harvester which can be added without major constructive modifications and which features a high resolution.  
         [0006]     It is proposed to make available a measuring surface which is supported by a solid body articulation. This articulation makes available a pre-stress force which pre-stresses the measuring surface into its home position and which permits at the same time small movements of the measuring surface. Crop material picked up or processed by the harvester exerts either, through its weight or a strike, a force and/or some torque on the measuring surface which is thereby directed against the pre-stress force. The movements of the measuring surface are in the range of nm, μm or single digit mm and are being captured by a sufficiently accurate position capturing device, preferably in the form of a laser interferometer or another optical absolute or incremental distance measuring system. In the event that for calculating the throughput, which may be the mass or volume throughput per time unit, any information is needed about the material speed, this may be determined directly, e.g. by radar or by applying the applicable conveyor speed in each case.  
         [0007]     An advantage of the invention is that a mass flow rate can be captured with high resolution.  
         [0008]     The measuring surface can be integrated into the wall of a conveyor channel through which the crop material is transported, which is to say that it may be formed by a wall section of the conveyor channel so that no additional elements need to be inserted into the conveyor channel.  
         [0009]     The invention is particularly suitable for capturing the throughput on harvesters such as combines, mowers, field choppers, bale presses or self loading forage boxes or associated harvesting attachments, e.g. in the form of pick-ups, corn pickers or corn husking rolls or slitters. The measured throughput values can be charted with the geo-reference system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     In the drawings are shown two versions of the invention which are described in more detail below.  
         [0011]      FIG. 1  is a harvesting machine in the form of a field chopper;  
         [0012]      FIG. 2  is a schematic side view of a measuring device for the harvesting machine in  FIG. 1 ;  
         [0013]      FIG. 3  is a harvesting machine in the form of a combine; and,  
         [0014]      FIG. 4  is a schematic side view of a measuring device for the harvesting machine of  FIG. 3 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     A harvesting machine is shown in  FIG. 1  in the form of a self-propelled field chopper built on a frame  12  which is supported by the front and rear wheels  14  and  16 . Operation of the harvester  10  is controlled from a driver&#39;s cabin  18  from which the crop picking device  20  is visible. Crop material, such as corn, grass or similar material that has been picked up from the ground by the crop material pick-up device  20  is directed to a chopping drum  22  which chops it into small pieces and sends it to a conveyor  24 . The material exits the harvester  10  into an adjacent trailer or wagon by means of a rotatable discharge device  26 . Between the chopping drum  22  and the conveyor device  24  is located a regrinding device  28  through which the material to be conveyed is brought tangentially to the conveyor device  24 . In the following text indications of direction such as front and back refer to the forward movement of the harvester  10 .  
         [0016]     On the top of the driver&#39;s cab  18  an antenna  30  is mounted for receiving signals from satellites of the global positioning system (GPS), but any other positioning system may also be used. A computing device  32  is connected to the antenna  30  and a measuring device  34  which serves for capturing the throughput of the crop material through the harvester  10 . Crop throughputs are stored in georeference as yield cards by the computing device  32  and are displayed to the operator on a display device  36 .  
         [0017]     The measuring device  34  forms the bottom and back wall of a conveyor channel formed by the housing  44  of the conveyor device  24  and is shown in detail in  FIG. 2 . It includes a measuring surface  38  made of rigid material (steel sheet) which is fastened at its front and rear ends (in reference to the flow direction of the material as shown by the arrow  40 ) by so-called solid body articulations  42  on the bottom and back wall of the housing  44 . The solid body articulations  42  extend each over the entire width of the housing  44  or a portion thereof and are formed by sections of the wall of the housing  44  with a significantly reduced material thickness as compared to the rest of the housing. The manufacture of the solid body articulations  42  may be done through material removal or material deformation. The lateral edges of the measuring surface  38  may also be connected by solid body articulations to the adjacent wall of the housing  44  or a separating cut is provided there.  
         [0018]     The solid body articulations  42  pre-stress the measuring surface  38  into a home position, but they allow, when crop material strikes the measuring surface  38 , a microscopic movement of the measuring surface  38  with respect to the housing  44 .  
         [0019]     Depending on the material throughput, the rear section of the measuring surface  38  moves backwards, while the front section (running more or less horizontal) then moves downward. The movement of the measuring surface  38  is being captured by a laser inferometer  46  belonging to the measuring device  34  and which is connected to the computing device  32 . The latter calculates the current throughput, based on the signal from the laser inferometer  46  and if applicable based on the speed signal relating to the revolution of the conveyor device  24 . The laser inferometer is advantageously calibrated on a throughput of zero when no crop material is present; additional calibration points may be accepted with other crop throughputs known through other measurements (e.g. weighing of a trailer loaded with crop material). The zero calibration may be repeated by an operator input or automatically when no crop material is present which can be captured on the basis of the operating condition of the harvester or by suitable sensors. Suitable laser inferometers are known as such and are manufactured and marketed for instance by Carl Zeiss AG, Oberkochen, DE under the name Surfcom 3000.  
         [0020]     Measuring devices  34  as shown in  FIG. 2  may be located at any position on harvesters where material changes direction, so that the measuring surface  38  experiences a force, a pulse or a torque caused by the striking crop material. On a harvester  10  in the form of a field chopper such a measuring device  34  could also be positioned on the top of the delivery device  26 , preferably in its area that is nearest to the conveyor device  24 . In the case of combine it could be a wall against which the clean grain is thrown by the grain elevator.  
         [0021]      FIG. 3  shows another agricultural harvesting machine  50  in the form of a combine featuring a supporting structure  52  with wheels  54  engaged with the ground. A harvesting attachment  56  is used to pick up crop material and to direct it towards a slope conveyor. The harvested material is transported by the slope conveyor to a guide drum  60 . The guide drum  60  transports the material upward through an intake transition section  62  of a rotatable material processing unit  64 .  
         [0022]     The material processing unit  64  threshes and separates the crop material. Grain and chaff fall through the grates at the bottom of the material processing unit  64  into a cleaning system  66 . The cleaning system  66  eliminates the chaff and directs the clean grain to an elevator  68  for clean grain. The elevator  68  for clean grain deposits the clean grain in a grain container  70 . The clean grain in the grain container  70  can be discharged through a discharge worm conveyor  72  to a grain wagon, trailer or truck. Operation of the harvester  50  is controlled from an operator cab  74 .  
         [0023]     The harvesting machine  50  is also equipped with a measuring device  34  which is shown in detail in  FIG. 4 , to capture the material throughput. An antenna  30 , a computing device  32  and a display device  36  are also provided which in their construction and function correspond to the executed version of  FIG. 1 .  
         [0024]     The components of the measuring device  34  shown in  FIG. 4  correspond to those of the measuring device shown in  FIG. 2 . The measuring surface  38  is formed by the part of the bottom plate  86  of the screen box  66  which surrounds in a semicircular shape the cross-direction conveyor  84  and is connected to the bottom plate  86  by the solid body articulations  42 . This area forms a conveying channel where the throughput is captured. Here, too, the measuring surface  38  may extend over the entire length (seen in a sideways direction) of the cross-direction conveyor  84  or a partial area thereof and be connected, at the left and right ends in the forward direction, by solid body articulations  42  to the bottom plate  86  or may be separated therefrom by separating cuts. The material (cleaned grain) transported by the cross-direction conveyor  84  exerts, due to gravity, a force on the measuring surface  38  which will yield correspondingly in a downward direction, against the pre-stress force made available by the solid body articulations  42 . The vertical position of the measuring surface  38  is being captured by the laser inferometer  45  that is connected to the computing device  32 . To determine the throughput, the computing device  32  is connected to a sensor for measuring the revolutions of the cross-direction conveyor  84 . To avoid measuring errors, in case the harvesting machine  50  is working on a slope, appropriate sensors for the incline in the forward and sideways direction may be present and on the basis of whose signals the computing device  32  performs appropriate corrections. The measuring device  34  could also be used on a cross-direction conveyor for cross-over (not shown) or at the bottom of the grain container  70 .  
         [0025]     The measuring device  34  as per  FIG. 4  may be used in any location where crop material is transported over a surface. Examples would be intake channels of bale presses, self loading forage boxes, or other harvesting machines or bottom plates of harvesting attachments.  
         [0026]     The harvesting machines  10  and  50  are not stationary but are moved during operation across a field usually featuring some uneven spots. These relief variations, as do also any vibrations produced by working elements of harvesting machines  10 ,  50  (e.g. the engine or other rotating elements) lead also to accelerations of the measuring surface  38 . Because of the relatively rigid suspension at the solid body articulation  42  the measuring surface  38  is subject to less pronounced natural vibrations than conventional measuring surfaces pre-stressed by a spring, whereby measuring accuracy is improved.  
         [0027]     Should the vibrations of the measuring surface  38  be interfering in spite of this, the measuring surface can be mounted and dimensioned in such a manner that each interfering acceleration will be followed by an equally strong acceleration in reciprocal proportions. Over a longer period the measuring errors cancel each other out. Alternatively or additionally, a mechanical damper of the measuring surface  38  may be provided, for instance by a liquid bath or an additional mass, or the vibrations are compensated during the evaluation of the signals of the measuring device  34 , in particular by filtering and/or averaging.  
         [0028]     If a higher measuring accuracy is required, one could also use, instead of the measuring device  34  described so far which works in a single dimension, a version with as many as  6  measuring axes in order to determine all interfering accelerations and to be able to compensate for them through software during the computer-assisted evaluation. For a further increase of the measuring accuracy the principle of a measuring bridge could also be used. In addition to the position measuring device at the measuring surface  38  in this case an identical position measuring device is mounted to a reference system that is not integrated into the mass flow. This reference system should be located as close as possible to the actual measuring system. With this arrangement mechanical as well as thermal compensation of ambient influences is achieved. A part of the time-dependent changes in the mass flow system is also compensated.  
         [0029]     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.