Abstract:
An implement with a ground working tool mounted on an arm pivotably movable between raised and lowered positions includes a pneumatic down pressure control system. The down pressure control system includes upper and lower mounts with an air spring located between them and having compressed and extended configurations with said arm raised and lowered respectively. A parallel plate mechanism maintains the upper and lower mounts in parallel relation and maintains a relatively consistent down pressure of the air spring. Multiple air springs can be provided on an implement and pneumatically interconnected by an air line for simultaneously charging to a constant air pressure.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosed technology relates generally to suspension systems, and in particular an air spring down-pressure system for an agricultural implement. 
         [0003]    2. Description of the Related Art 
         [0004]    Agricultural implements that work the soil require mechanical force to penetrate down into the soil and move forward through the soil. Typically, penetrating force, also referred to as down pressure, is generated by the weight of the implement and mechanical force created by a suspension system using helical or leaf springs. 
         [0005]    Grain drills, also referred to as openers, are agricultural tilling implements that allow farmers to quickly and efficiently plant row crops using agricultural machinery. Openers are independent units attached to a structure, such as a tool bar, which is pulled behind a tractor. Multiple openers are usually attached to a tool bar and spaced apart at specific intervals. As the opener moves forward, it plants seeds in the soil by penetrating and separating the soil with a pair of overlapping discs to create a trench in which a seed is deposited. Additional furrow-closing components flank the discs and trail behind them for returning the soil to the open furrow or trench and for covering the deposited seeds. 
         [0006]    The depth of the trench created by the discs depends upon the condition of the soil, the amount of residue present, the opener and the amount of down pressure exerted by the opener against the ground. Down pressure is created using a suspension system that generates mechanical force to bias the opener discs down. Conventional openers typically have suspension systems with springs for exerting down pressure. However, due to the spring constant factors associated with mechanical springs, down pressure from spring action varies over the range-of-travel, with greater forces being exerted at full compression/extension conditions. Moreover, the mechanical linkages and pivot points associated with springs tend to increase problems associated with operating and maintaining such spring-based conventional implement suspension systems, still further, because of the mechanical geometries of spring-based suspension systems, they are vulnerable to contamination from soil and residue displaced during the planting process. Other disadvantages include lack of adjustability and frequency of repairs and maintenance. 
         [0007]    What is needed is a suspension system with fewer moving parts and pivot points than conventional systems, which has fewer wear points, which provides more consistent down pressure throughout its vertical travel, and which permits infinite down pressure adjustment from a single control point. Heretofore there has not been available a suspension system with the advantages and features of the disclosed subject matter. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In a suspension system embodying the principles of the disclosed subject matter, an air spring assembly disposed between upper and lower mounts provides consistent and adjustable down pressure on the arm of an agricultural implement by keeping the mounts parallel to each other using a guide rod. An upper mount is pivotally connected to a pivot point at one end of the implement arm, and a lower mount is pivotally connected to a pivot point on the arm located rearward of the end pivot point. The upper and lower mounts each contain an elongated aperture and an adjacent hole. A sleeve type air spring is secured within the apertures permitting repositioning between front and rear aperture locations. A guide rod secured within the lower mount hole extends up and through a wear bushing located within the upper mount hole. 
         [0009]    In operation, as the upper and lower mounts move toward or away from each other, the guide rod slides within the wear bushing, keeping the upper and lower mounts in a parallel relationship as the air spring provides consistent down pressure upon the implement arm. 
         [0010]    The amount of down pressure exerted by the suspension system upon the arm can be adjusted by varying the air pressure within the air spring, by moving the air spring assembly forward or backward within the apertures, or both. The air springs are connected to a source of air pressure such as an air compressor. Moving the air spring assembly in a rearward position within the apertures creates a longer distance between the pivot point at the end of the arm and the pivot point of the bottom plate, thereby decreasing the mechanical advantage of the arm and increasing the relative down pressure of the suspension system. Conversely, moving the air spring assembly forward in the apertures increases the mechanical advantage of the arm and decreases the relative down pressure of the suspension system upon the arm. For example, field conditions may necessitate greater down pressure in opener assemblies to accommodate hard ground conditions, field debris and similar conditions associated with greater opener resistance. Moreover, selective opener assemblies, such as those following the tractor wheels and encountering compacted soil conditions, may require greater down pressure for constant-depth furrows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The drawings constitute a part of this specification and include exemplary embodiments of the disclosed subject matter illustrating various objects and features thereof, wherein like references are generally numbered alike in the several views. 
           [0012]      FIG. 1  is an upper, right, rear perspective view of an air spring suspension system embodying the principles of the disclosed subject matter. 
           [0013]      FIG. 2  is a right side elevational view of the air spring suspension system. 
           [0014]      FIG. 3A  is an enlarged, fragmentary elevational view of the air spring suspension system taken generally within circle  3 A in  FIG. 2  and shows the air spring in a neutral condition. 
           [0015]      FIG. 3B  is an enlarged, fragmentary elevational view of the air spring suspension system taken generally within circle  3 A in  FIG. 2  and shows the air spring in a compressed condition. 
           [0016]      FIG. 3C  is an enlarged, fragmentary elevational view of the air spring suspension system taken generally within circle  3 A in  FIG. 2  and shows the air spring in an extended condition. 
           [0017]      FIG. 4A  is a partial, fragmentary left-front perspective view of the air spring suspension system taken generally within circle  4 A-B in  FIG. 1  and shows the air spring in a rearward position. 
           [0018]      FIG. 4B  is a partial, fragmentary left-front perspective view of the air spring suspension system taken generally within circle  4 A-B in  FIG. 1  and shows the air spring in a forward position. 
           [0019]      FIG. 5  is an enlarged, fragmentary view showing a pneumatic system connected to the air spring assemblies. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     I. Introduction and Environment 
       [0020]    As required, detailed aspects of the disclosed subject matter are disclosed herein; however, it is to be understood that the disclosed aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art how to variously employ the present invention in virtually any appropriately detailed structure. 
         [0021]    Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, up, down, front, back, right and left refer to the invention as orientated in the view being referred to. The words, “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the aspect being described and designated parts thereof. Forwardly and rearwardly are generally in reference to the direction of travel, if appropriate. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning. 
       II. Embodiment of the Suspension System  2   
       [0022]    Referring to the drawings in more detail, the reference numeral  2  generally designates a suspension system embodying the principles of the disclosed subject matter. Referring to  FIGS. 1-2 , an embodiment of the suspension system  2  is shown in use with an agricultural implement, specifically an opener assembly  80  for depositing seeds in the soil. The opener assembly  80  generally consists of a rearwardly extending arm  82  having a box-like construction, mounting a press wheel  86  on a trailing arm  84 , and mounting a pair of opener discs  88  flanked laterally by a soil compactor subassembly  90  including a pair of compactor blades  91  straddling the discs  88 . The opener assembly  80  is designed to be secured at the front end to a tool bar  78  by the suspension system  2 . The tool bar  78  extends laterally behind a tractor or other suitable farm machinery. The suspension system  2  generally operates by biasing the opener assembly  80  against the tool bar  78  forcing the pair of slightly overlapping opener discs  88  down into the soil causing lateral displacement of the soil, and creating a furrow or trench in which the seeds are deposited. As the opener assembly  80  moves forward, the seeds are deposited and the displaced soil is returned to the furrow by the soil compactor  90  and the trailing press wheel  86 . 
         [0023]    Referring to  FIG. 3A , the suspension system  2  consists of an air spring assembly  50  and a guide rod  42  disposed between a base bracket or lower mounting  30  and a tool bar bracket or upper mount  4 . The upper mount  4  is fabricated from steel and has opposite sidewalls  6  with arms  8  extending rearwardly from an upper portion, and legs  10  depending from the bottom. An upper plate  12  extends rearwardly from the upper portion of the sidewalls  6  beyond the back end of the arms  8 . The upper plate  12  has a slotted aperture  14  for receiving the threaded neck  58  of the air spring  52 , and a hole (not shown) for attachment of a tubular wear bushing  46 . The forward portions of the side walls  6  partially circumscribe the tool bar  78  by contacting the rear, upper and lower surface of the tool bar  78 . Generally L-shaped fasteners  18  demountably secure the upper mount  4  to the tool bar  78  by nuts  20 . The legs  10  straddle the forward portion of the opener assembly arm  82 , which is pivotally mounted thereto at a first pivot  21  by a fastener  22 , such as a bolt. At the rear of each leg  10  a rectangular tab  92  that protrudes perpendicular from each sidewall of the arm  82  permitting rotation of the arm  82  about the bolts  22  between upper and lower stops  26 ,  28  located within a recess  24 . 
         [0024]    A metal base bracket or lower mount  30  disposed above the arm  82  consists of a lower plate  32  and sidewalls  38  depending therefrom that astride the arm  82 . The lower mount  30  is pivotally affixed to the arm  82  at a second pivot  39  by fasteners  40 , such as bolts, that extend through the sidewalls  38  and into the arm  82 . The lower plate  32  has an aperture  34  at its rear portion receiving a bolt  64  for securing the air spring assembly  50  thereto, and a hole (not shown) at a forward end for receiving the threaded end of the guide rod  42 . 
         [0025]    The air spring assembly  50  consists of a sleeve type air spring  52  with an upper or first end  53  and a lower or second end  55  composed of a flexible reinforced rubber sleeve disposed between a bead plate  54  at the top, and a lower end dome  56  at the bottom. The upper portion of the air spring assembly  50  is secured to the upper plate  12  by positioning the threaded neck  58  of the valve  60  protruding from the top of the bead plate  54  in the aperture  14  of the upper plate  12  and securing a nut  62  on the threaded neck  58 . The lower portion of the air spring assembly  50  is secured against the lower plate  32  by a bolt  64  threadably received within a blind nut (not shown) disposed within the lower end of the dome  56 . A threaded guide rod  42  is secured within the passage (not shown) of the lower mount  30  with nuts  44  and extends upwardly through a tubular wear bushing  46  disposed within a hole (not shown) in the upper plate  12 . The wear bushing  46  is manufactured from a Nylatron® material and is threadably secured within the hole (not shown) by a ring nut  48 . 
       III. Operation 
       [0026]    The suspension system  2  provides consistent down pressure upon the opener assembly  80  because the air spring assembly  50  is mounted to two parallel surfaces. Furthermore, the amount of down pressure created by the suspension system  2  can be increased or decreased by adjusting the air pressure within the air spring  52 , moving the position of the air spring assembly  50  forward or rearward within the apertures  14 ,  34 , or both. 
         [0027]    Referring to  FIG. 3A , the suspension system  2  is shown in a neutral position with the air spring assembly  50  located at a forward-most position within the apertures  14 ,  34  ( FIG. 4A-4B ). The use of the air spring assembly  50  in conjunction with the guide rod  42  provides two points of alignment for the suspension system  2 , thereby positioning the upper plate  12  and the lower plate  32  in a parallel orientation. Referring to  FIG. 3B , the suspension system  2  is shown in a maximum compressed position. As the suspension system  2  transitions from a neutral position to a compressed position, the arm  82  of the opener assembly  80  moves up, pivoting about the fastener  22 . The guide rod  42  slides up within the wear bushing  46  causing the lower mount  30  to pivot about the fastener  40 , in turn maintaining the parallel relationship between the upper and lower plates  12 ,  32 . Constraining the upper and lower plates  12 ,  32  to a parallel relationship allows the compressing air spring  52  to exert a consistent down pressure throughout compression. The suspension system  2  is prevented from over compression by a tab  92  that contacts an upper stop  26  preventing further upward movement of the opener assembly  80 . 
         [0028]    Referring to  FIG. 3C , the suspension system  2  is shown in a maximum extended position. Again, as the suspension system  2  transitions from a neutral position to an extended position, the guide rod  42  slides down within the wear bushing  46 , causing the upper plate and lower plates  12 ,  32  to remain parallel permitting consistent down pressure by the air spring assembly  50 . The suspension system  2  reaches maximum extension when the tab  92  contacts the lower stop  28 , preventing further downward movement of the opener assembly  80 . 
         [0029]    Referring to  FIG. 5 , the air pressure within the air spring  52  of each air spring assembly  50  can be maintained by an air compressor  70  located at a front end of a tow hitch connected to the tool bar  78 . The air compressor  70  can be powered by the tractor electrical system. Multiple air spring assemblies  50  are connected in a series by an air line  68  running between T-fittings  66  attached to the valves  60  of the air spring assemblies  50 . The air line  68  also includes an air inlet valve  72  for connection to a compressed air source other than the electrical compressor  70 , such as a compressor or an air bottle, whereby the air springs  52  of multiple air spring assemblies  50  can be simultaneously charged up to a desired, common air pressure. Air springs  52  could also be charged to and maintain at different pressures for selective variable down force for accommodating different conditions encountered along the opener implement. 
         [0030]    The movement of the air spring assembly  50  between forward and rearward positions within the apertures  14 ,  34  allows for adjustment of the down pressure exerted by the suspension system  2  because the change in location changes the mechanical advantage of the system  2 . The arm  82  of the opener assembly  80  functions as a lever that pivots about a fulcrum located at the fasteners  22  in the legs  10 . The air spring assembly  50  operates as a resistive force creating down pressure in response to biasing of the opener assembly  80  against the tool bar  78  due to contact of the opener discs  88  with the ground. When the air pressure in the air spring  52  is constant, and the air spring assembly  50  is positioned forward or rearward within the apertures  14 ,  34  the amount of down pressure exerted by the suspension system  2  varies. For example,  FIG. 4A  shows the air spring assembly  50  in a rearward air spring position creating a relatively long distance between the fulcrum and the air spring assembly  50 . As a result, the suspension system  2  is capable of relatively high down pressure due to the mechanical advantage caused by the relative positions of the air spring assembly  50  and the fasteners  22 . Referring to  FIG. 4B , the air spring assembly  50  is shown in a forward air spring position creating a relatively short distance between the fulcrum and the air spring assembly  50 , resulting in an increase in mechanical advantage and a decrease in available down pressure. 
         [0031]    It will be appreciated that the components of the suspension system  2  can be used for various other applications. Moreover, the suspension system  2  can be fabricated in various sizes and from a wide range of suitable materials, using various manufacturing and fabrication techniques. 
         [0032]    It is to be understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects.