Abstract:
A combine including a frame, power unit and a crop gathering and processing device. A grain tank is mounted on the frame. An elongated closed end tube is vertically oriented within the grain tank and has a plurality of uniformly spaced openings along its length. A pneumatic pump pressurizes the interior of the tube. A pressure sensor senses the interior pressure of the elongated tube, so that grain building up therein selectively covers the plurality of openings to cause a proportionate increase in air pressure.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/245,733, entitled “Pneumatic Grain Level Sensor and Method Therefore” and filed Oct. 23, 2015, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to agricultural machinery, and, more particularly, for apparatus and methods for determining the level of grain within a grain tank. 
         [0004]    2. Description of the Related Art 
         [0005]    As the agricultural technology is evolving there is an ever increasing drive towards efficiency. This drive for efficiency is apparent in the use of agricultural combines to harvest even greater quantities of grain or crop material for a given pass through the field. The combine harvests, collects and processes the crop to extract the grain which is placed in a grain tank for accumulation until it is full at which point it is discharged into another vehicle for transport from the field. It becomes important to have 1) a reliable means of determining the level of grain within a tank so that delivery to a transport vehicle only takes place when the grain tank is full and 2) means to determine the exact level, and, by association, the rate the grain tank is filling so that the time to fill can be predicted. 
         [0006]    This has prompted a number of approaches to determine fullness within the tank. An early approach was a window giving a visual indication to the operator when the tank is nearly full. However, this posed a distraction to the operator who is called on to operate a large and increasingly complex piece of machinery. Other approaches have been to have pressure level switches at various locations within the tank to provide an indication when the tank is, for example, ¾ full and then full. Other devices using ultrasonic or radar detectors have been proposed. While these do provide a means of determining the fullness within the grain tank, they do so at increased cost and complexity. 
         [0007]    Accordingly, what is needed in the art is a simplified and effective way to continuously measure the increase in quantity of grain within a grain tank. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention seeks to continuously determine the level of grain within a combine grain tank, expandable to mobile gain carts, semi-trailers, grain storage silos, grain storage elevators, using a minimum of sensors. 
         [0009]    In one form, the invention is a grain level sensor for a grain tank. The sensor includes an elongated closed end tube positioned within the tank and having a plurality of spaced openings along its length. A pneumatic pump pressurizes the interior of the tube and a pressure sensor is provided for sensing the interior pressure. The elongated tube is oriented relative to the grain tank so that grain building up therein selectively covers the plurality of openings to cause an increase in sensed pressure. 
         [0010]    In another form, the invention is a combine including a frame, power unit and a crop gathering and processing device. A grain tank is mounted on the frame and a conveyor delivers grain to the grain tank from the crop gathering and processing device. An elongated closed end tube is positioned within the grain tank and has a plurality of spaced openings along its length. A pneumatic pump pressurizes the interior of the tube. A pressure sensor senses the interior pressure of the elongated tube, the elongated tube being oriented relative to the grain tank so that grain building up therein selectively covers the plurality of openings to cause an increase in air pressure. 
         [0011]    In yet another form, the invention is a method for determining the level of a grain in a tank. The method includes the steps of placing into the tank a closed end elongated tube having a plurality of spaced openings along its length and pressurizing the interior of the tube to a given level. The interior pressure of the tube is sensed without grain in the tank. Subsequently the interior pressure of the tube is sensed as the grain accumulates within the tank. The subsequent pressure is compared to the empty pressure as a measure of the grain within the tank. 
         [0012]    One benefit of the invention is the provision of a continuous measurement of the quantity of grain within a tank using essentially a single sensor. 
         [0013]    Another benefit is adding a minimum of hardware to an agricultural combine while having a continuous quantity measurement. 
         [0014]    Another benefit is that the sensing hardware is contained entirely within the grain tank, minimizing the chance of damage from physical contact with trees or structures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0016]      FIG. 1  is a side view of an embodiment of a combine with which the present invention may be utilized; 
           [0017]      FIG. 2  is a partial cross section view of the combine of  FIG. 1  showing one embodiment of the present invention; and, 
           [0018]      FIG. 3  is a plan view of the combine of  FIG. 1  showing another embodiment of the present invention. 
       
    
    
       [0019]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The terms “grain”, “straw” and “tailings” are used principally throughout this specification for convenience but it is to be understood that these terms are not intended to be limiting. Thus “grain” refers to that part of the crop material which is threshed and separated from the discardable part of the crop material, which is referred to as non-grain crop material, MOG or straw. Incompletely threshed crop material is referred to as “tailings”. Also the terms “forward”, “rearward”, “left” and “right”, when used in connection with the agricultural harvester and/or components thereof are usually determined with reference to the direction of forward operative travel of the harvester, but again, they should not be construed as limiting. The terms “longitudinal” and “transverse” are determined with reference to the fore-and-aft direction of the agricultural harvester and are equally not to be construed as limiting. 
         [0021]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an agricultural harvester in the form of a combine  10 , which generally includes a chassis  12 , ground engaging wheels  14  and  16 , a header  18 , a feeder housing  20 , an operator cab  22 , a threshing and separating system  24 , a grain cleaning system  26 , a grain tank  28 , and an unloading auger  30 . It should be appreciated that while the agricultural harvester is shown as combine  10 , the agricultural harvester according to the present invention can be any type of construction that allows for crop material to be harvested such as a conventional combine (which does not have a rotor), rotary combine, hybrid combine, chopper harvester, etc. 
         [0022]    Front wheels  14  are larger flotation type wheels, and rear wheels  16  are smaller steerable wheels. Motive force is selectively applied to front wheels  14  through a power plant in the form of a diesel engine  32  and a transmission (not shown). Although combine  10  is shown as including wheels, is also to be understood that combine  10  may include tracks, such as full tracks or halftracks. 
         [0023]    Header  18  is mounted to the front of combine  10  and includes a cutter bar  34  for severing crops from a field during forward motion of combine  10 . A rotatable reel  36  feeds the crop into header  18 , and a double auger  38  feeds the severed crop laterally inwardly from each side toward feeder housing  20 . Feeder housing  20  conveys the cut crop to threshing and separating system  24 , and is selectively vertically movable using appropriate actuators, such as hydraulic cylinders (not shown). 
         [0024]    Threshing and separating system  24  is of the axial-flow type, and generally includes a rotor  40  at least partially enclosed by and rotatable within a corresponding perforated concave  42 . The cut crops are threshed and separated by the rotation of rotor  40  within concave  42 , and larger elements, such as stalks, leaves and the like are discharged from the rear of combine  10 . Smaller elements of crop material including grain and non-grain crop material, including particles lighter than grain, such as chaff, dust and straw, are discharged through perforations of concave  42 . 
         [0025]    Grain which has been separated by the rotor  40  and perforated concaves  42  falls onto a main grain pan  44  and is conveyed toward grain cleaning system  26 . Grain cleaning system  26  may include an optional pre-cleaning sieve  46 , an upper sieve  48  (also known as a chaffer sieve), a lower sieve  50  (also known as a shoe sieve), and a cleaning fan  52 . Grain on sieves  46 ,  48  and  50  is subjected to a cleaning action by fan  52  which provides an airflow through the sieves to remove chaff and other impurities such as dust from the grain by making this material airborne for discharge from straw hood  54  of combine  10 . Main grain pan  44  and pre-cleaning sieve  46  oscillate or reciprocate in a fore-to-aft manner to transport the grain and finer non-grain crop material to the upper surface of upper sieve  48 . Upper sieve  48  and lower sieve  50  are vertically arranged relative to each other, and likewise oscillate in a fore-to-aft manner to spread the grain across sieves  48 ,  50 , while permitting the passage of cleaned grain by gravity through the openings of sieves  48 ,  50 . 
         [0026]    Clean grain falls to a clean grain auger  56  positioned crosswise below and in front of lower sieve  50 . Clean grain auger  56  receives clean grain from each sieve  48 ,  50  and from bottom pan  58  of grain cleaning system  26 . Clean grain auger  56  conveys the clean grain laterally to a generally vertically arranged elevator  60 , which can also be referred to as a grain elevator, for transport to grain tank  28 . Tailings from grain cleaning system  26  fall to a tailings auger on  62 . The tailings are transported via tailings auger  64  and return auger  66  to the upstream end of grain cleaning system  26  for repeated cleaning action. A pair of grain tank augers  68  at the bottom of grain tank  28  conveys the clean grain laterally within grain tank  28  to unloading auger  30  for discharge from combine  10 . The non-grain crop material proceeds through a residue handling system  70 . Residue handling system  70  may include a chopper, counter knives, a windrow door and a residue spreader. 
         [0027]    In the course of harvesting grain, it becomes important for the operator to ascertain the quantity of grain accumulating within grain tank  28 . The embodiments of the present invention illustrated in  FIGS. 1 and 2  achieve this with a simplified arrangement of components. 
         [0028]    Referring now to the drawings, and more particularly to  FIG. 2 , the grain tank  28  has an extension wall  71  at least along a portion of its periphery and is hinged to grain tank  28  by a hinge  72 . An upper open periphery  73  defines the top of the grain tank  28  and extension  71 . A perforated tube  74  extends vertically from the bottom of grain tank  28  to its upper most reaches. Tube  74  has a plurality of openings  76  uniformly spaced along its length. The size of the openings  76  is sufficiently small to be smaller than the minimum expected size of the grain anticipated to be housed within grain tank  28 . Another embodiment could be where the size of the openings  76  is larger than the minimum expected size of the grain anticipated to be housed within grain tank  28  and guarded by fabric or screen having appropriate porosity. The tube  74  has a first section  78  in grain tank  78  and a second section  80  secured to grain tank extension  71 . The first and second section  78  and  80  are connected fluidly through a flexible joint  82  such as a flexible tube. 
         [0029]    A pressure sensor  84  is positioned at the upper end of perforated tube  74 , thus closing off one end of the tube. A pneumatic pressure supply  86  closes off the opposite end of perforated tube  74 . The pneumatic pressure supply  86  may be a tap into the pneumatic pressure supply of the combine  10  or it may be a separately dedicated pneumatic pump and motor. The output of pneumatic pressure supply  86  is coupled to perforated tube  74  by an outlet tube  88 . A pressure sensor  90  generates a signal reflecting the supply pressure from pneumatic pressure supply  86 . A switch level  92 , near the upper open periphery  73 , generates a signal reflecting a full grain tank  28  including the extension  71 . Switch  92  may be of the contact type which changes state when contacted or covered by grain. The signals from the various sensors are sent to an electronic control unit  94  ECU by a line  96  leading from pressure sensor  84 , line  98  leading from switch level  92  and line  100  leading from supply pressure sensor  90 . 
         [0030]    The pressure with the closed end perforated tube  74 , when the tank is empty, reflects a pressure level that is at its lowest and is set by the supply pressure from the pneumatic pressure supply  86 , the size and number of holes  76 . As the grain tank  28  and extension  71  are filled, more of the openings  76  are closed off thus restricting the outflow of air from the perforated tube  74  and in turn increasing the pressure sensed by pressure sensor  84 . The pressure continues to increase in generally a proportional manner until the switch level  92  signals that the grain tank  28  is full. At this point, the pressure indicated by sensor  84  is that for a full tank and substantially closed off perforated tube  74 . This signal is computed by the ECU  94  to be the full pressure signal and any signal below that is in proportion to the quantity of grain within the tank  28  and extensions  20 . The pressure sensor  90  provides an input to ECU  94  that is useful when the pneumatic pressure supply  86  varies. The overall proportion and absolute pressure increases are adjusted according to the variation in pressure of the pneumatic pressure supply  86 . The signal reflecting the changes in pressure is indicated on component  95  connected to ECU by line  93 . Component  95  may be calibrated in terms of percentage of grain in the tank or in any other convenient parameter such as time to fill, distance to full, area (acres) to full. 
         [0031]    The arrangement set forth above offers a precise and continuous measurement of the quantity of grain within the grain tank  28  and the extension  71  with a minimum of sensors. Unlike the prior art devices having multiple contact sensors or non-contact electronic sensors, it provides continuous measurement with straight forward and inexpensive components. In addition, the elements making up the system are robust and relatively unaffected by the otherwise contaminated environment of the combine  10 . 
         [0032]    The arrangement shown in  FIG. 2  senses the continuous change in level of the grain within tank  28  and extension  71 . The principle used in  FIG. 1  may be used also in the arrangement shown in  FIG. 3  which shows a full grain pneumatic sensor. As such, this arrangement may be used in parallel with the components shown in  FIG. 2 . Specifically referring to  FIG. 3 , the upper open periphery  73  of grain tank  28 , including extensions  71 , has a plurality of perforated tubes  100 ,  102 ,  104  and  106  interconnected by flexible connecting tubes  108 . A pressure sensor  110  is provided to sense the pressure within the closed end tube made up by the individual tubes  100  to  106 . A pneumatic pressure supply  112  supplies pneumatic pressure to the interior of the tube as is the case with the arrangement of  FIG. 1 . 
         [0033]    As illustrated, the tubes may be interconnected to form a continuous closed end perforated tube or they may be individual tubes. In either case, as the grain fills the tank, the pressure sensed by sensor  110  remains at its&#39; lowest until one of the legs of tubes is covered with grain at which point the pressure is increased from the earlier lowest pressure. As a result, the tubes sense when grain tank  28  is full, even when the combine  10  is on a slope and one side of the perforated tubes is covered before the others. This enables the operator to determine that the tank is full and needs emptying before it spills out over the low side. The arrangement of  FIG. 3  shows a simplified way of determining a full grain tank even when the combine is operating on a slope. 
         [0034]    In both configurations, the quantity of grain or the fullness of the tank are determined with readily obtainable inexpensive and durable sensors that operate reliably within the agricultural combine environment. 
         [0035]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.