Abstract:
The primary distribution hoses on the tillage implement of a pneumatic seeding machine are of different lengths as needed to reach distribution heads or splitters on the implement that further divide the primary streams of materials into individual streams leading directly to the ground-engaging openers of the implement. Notwithstanding the differential in hose length, outlet pressures at the distribution heads are made uniform through the provision of internal flow restrictors associated with those hoses that are shorter than the longest hoses on the machine. Throat diameters of the restrictors vary in accordance with the pressure drop that is needed to match the difference in hose length between the longest hose and the restricted hose. In a preferred embodiment, the restrictors are mounted within nipples on the coupling assembly that releasably connects conduits from a seed cart with the primary hoses on the implement.

Description:
TECHNICAL FIELD 
   The present invention relates to pneumatic seeding machines typically referred to as “air seeders” and, more particularly, to a way of achieving uniform delivery of seeds to all destination points on the machine, notwithstanding the fact that such points are located at a variety of different distances from the common source of airflow. 
   BACKGROUND AND SUMMARY 
   As air flows through a duct, such as a tube or hose, it loses kinetic energy, in the form of pressure, due to friction. Such pressure drop is a function of a number of different factors, including the shape and size of the duct and its length. 
   In an air seeder utilizing a pneumatic conveyance system, the success of the system is dependent upon maintaining an adequate amount of airflow throughout the system to keep the seeds in suspension within the air stream. If the airflow is insufficient, the product will fall from the stream and begin to build up on the bottom of the tube or hose. If the condition persists, the airflow within the tube or hose will be reduced to zero, and the build up of seeds will eventually cause plugging. 
   Typically, all hoses on an air seeder are supplied by a common air source and the flow is split equally among the various hoses, which are of the same size and shape. However, the sufficiency of the airflow can be an issue if the hoses vary in length, in order to reach openers on the machine that are unequally spaced from the air source. The different pressure drops caused by differences in hose length may result in plugging or uneven distribution of the seeds among the openers. 
   One way of keeping the pressure drop uniform throughout all hoses is to equalize their lengths. However, this means that hoses which deliver to locations closer to the source than others will necessarily have surplus lengths that are not needed, except for pressure uniformity purposes. This surplus hosing increases costs, stretches out set up and assembly time, wastes space, and looks cluttered and unattractive. 
   The present invention allows all the hoses to be as long or as short as necessary to reach their particular locations on the machine, without causing different pressure drops due to the different lengths. Internal airflow restrictors are utilized in the shorter hoses to create pressure drops to match those of the longer hose lengths. Different size restrictors are utilized in different hoses, depending upon the amount of pressure drop required to establish uniformity throughout all hoses. 
   In a preferred embodiment of the invention, the necessary flow restrictors are incorporated into a coupling assembly which detachably joins hoses from the seed reservoir cart with primary hoses on the seeding implement itself. Nipples on the coupling assembly may be fitted internally with appropriately dimensioned restrictors so that the restrictors are essentially hidden from view and require minimal maintenance. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary side elevational of a seeding machine incorporating the principles of the present invention; 
       FIG. 2  is a fragmentary, schematic top plan view of a prior art machine in which the primary seed distribution hoses are all of the same length so as to maintain equal outlet pressures at the discharge ends of the hoses; 
       FIG. 3  is a fragmentary, schematic top plan view of a machine in accordance with the present invention employing different hose lengths and airflow restrictors as appropriate to achieve equal hose pressures; 
       FIG. 4  is an enlarged, exploded isometric view of the coupling assembly between the seed reservoir cart and the planting implement illustrating the manner in which restrictors in accordance with the present invention may be incorporated into the coupling assembly; 
       FIG. 5  is a side elevational view of the coupling assembly on a more reduced scale than  FIG. 4  and illustrating the restrictors installed within hose nipples of the coupling assembly; 
       FIG. 6  is an enlarged, end elevational view of one of the restrictors installed within a hose nipple of the coupling assembly; 
       FIG. 7  is a fragmentary cross-sectional view thereof taken substantially along line  7 — 7  of  FIG. 6 ; 
       FIG. 8  is an end elevational view of another restrictor having a larger internal throat diameter than the restrictor of  FIGS. 6 and 7 ; and 
       FIG. 9  is a cross-sectional view of the restrictor of  FIG. 8  taken substantially along line  9 — 9  of that figure. 
   

   DETAILED DESCRIPTION 
   The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
   The seeding machine  10  shown in  FIG. 1  includes a mobile cart  12  containing a supply of seeds and/or fertilizer, and a planting implement  14  which is supplied seeds by cart  12 . Cart  12  and implement  14  are adapted to be towed by a tractor (not shown) so that the seeds and/or fertilizer may be deposited into the ground as the machine is advanced across the field by the tractor. Although the implement  14  has been illustrated in a leading relationship with the cart  12 , the order of appearance could be reversed with the cart being connected directly to the tractor and the implement  14  being towed by the cart. 
   As is typical, cart  12  includes one or more reservoirs  16  and  18  as well as a blower  20  that provides a known volumetric flow rate of air at a constant pressure. The volumetric airflow from blower  20  is divided equally across a number of conduits  22  that pass beneath reservoirs  16 ,  18  and receive metered supplies of materials therefrom. Conduits  22  may comprise pipes or hoses, or a combination of both. In the illustrated embodiment, adjacent the front of cart  12  the conduits  22  take the form of a number of flexible hoses that interface with primary supply hoses  24  on implement  14  at one or more coupling assemblies  26  (also known as “break-aways”) adjacent the rear of implement  14 . Broadly speaking, the conduits  22  and the primary hoses  24  collectively comprise structure defining tubular airflow passages for delivering seeds entrained within airstreams to predetermined destinations on the implement  14 . As noted below, the lengths of some of such passages are shorter than others. 
   As is conventional, implement  14  includes a mobile frame  27  that carries a number of ground engaging tools  28  for opening furrows in the soil and depositing seeds into such furrows as the machine advances. The primary hoses  24  of implement  14  supply the seeds to distribution devices  30  on frame  27  ( FIG. 3 ) which split up the flow of seeds into a number of separate streams and deliver them via smaller secondary tubes (not shown) to the individual tools  28 . Distribution devices  30  may take the form of horizontal, flat fan dividers as described in U.S. Pat. No. 4,717,289 owned by the assignee of the present invention and hereby incorporated by reference into the present specification. Alternatively, the distribution devices  30  may take avariety of other forms in common use in the industry. 
   In the illustrated embodiment, a pair of coupling assemblies  26  are provided on the implement  14  as shown in  FIG. 3 . The left coupling assembly in this figure has been designated  26 L, while the right coupling assembly has been designated as  26 R. In the description which follows, only the left coupling assembly  26 L will be explained in detail, with the understanding that the right coupling assembly is similarly constructed. 
   As illustrated in  FIG. 3 , there are four distribution devices  30  that serve the tools  28  on the left side of implement  14 . Correspondingly, four primary supply hoses  24   a ,  24   b ,  24   c , and  24   d  deliver seeds to the four devices  30 . These four primary supply hoses are also illustrated in  FIG. 4 . Hoses  24   a  and  24   b  are the shortest hoses in the group, such as  2 ′ long, while hose  24   c  is of intermediate length, such as  12 ′ long, and hose  24   d  is the longest, such as  22 ′ long. Notwithstanding the different length of the hoses  24   a – 24   d , in accordance with the present invention the outlet pressures at the four distributing heads  30  are all substantially equal to one another. 
   As illustrated in  FIG. 4 , and also  FIG. 5 , coupling assembly  26 L comprises a support including a generally L-shaped, upright stand  32  that is clamped at its lower end to a beam  34  associated with frame  27 . The support further includes an upright mounting plate  36  affixed to the upper end of stand  32  and having four horizontally disposed hose nipples  38   a ,  38   b ,  38   c  and  38   d  projecting forwardly therefrom. It will be understood that nipples  38   a – 38   d  are aligned with corresponding holes (not shown) in plate  36  so that streams of air, seeds and fertilizer can pass through plate  36  and nipples  38   a – 38   d  from the conduits  22  associated with supply cart  12 . Hoses  24   a – 24   d  slip onto the outside of and receive corresponding nipples  38   a - 38   d . Hose clamps  40  or other suitable means may be used to secure hoses  24   a – 24   d  onto nipples  38   a - 38   d.    
   Coupling assembly  26 L further includes a second upright mounting plate  42 , although plate  42  is not fixed to stand  32 . Like plate  36 , plate  42  has four holes  44  therein adapted to be aligned with corresponding holes in plate  36  and with nipples  38   a – 38   d  when plate  42  is secured up against plate  36  as illustrated in  FIG. 5 . A gasket  46  having holes  48  aligned with holes  44  in plate  42  and those in plate  36  may be sandwiched between plates  36  and  42 . Releasable bolts  50  fitting within notches  52  and  54  in the side edges of plates  36  and  42  respectively maybe used to releasably secure plate  42  up against plate  36 . 
   Conduits  22  associated with cart  12  are secured to nipples  56  ( FIG. 5 ) projecting from the backside of plate  42  in alignment with holes  44 . Hose clamps  58  retain conduits  22  on nipples  56 . As a result of their attachment to common mounting plate  42 , conduits  22  may be quickly and easily detached from implement  14  by simply releasing bolts  50  from plates  36 ,  42  when cart  12  is to be uncoupled from implement  14 . 
   In the illustrated embodiment, hose  24   d  is the longest of the four hoses. Thus, it will experience the most pressure drop. To equalize the pressure drop in all four of the hoses, hoses  24   a ,  24   b  and  24   c  are each provided with a restrictor capable of causing a pressure drop that matches the drop which would be produced by the length of surplus hose that must theoretically be added to each hose  24   a ,  24   b , and  24   c  to make them the same length as hose  24   d . Thus, if hose  24   d  is  22 ′ long and hose  24   c  is  12 ′ long, a restrictor capable of creating a pressure drop that matches the drop in a ten-foot length of hose is necessary for hose  24   c . Similarly, if the hoses  24   a  and  24   b  are each  2 ′ long, a restrictor is necessary for each of those hoses that is capable of creating a pressure drop matching the drop in a twenty-foot length of hose. Accordingly, the two short hoses  24   a  and  24   b  are each provided with the most restrictive restrictor  60 , the longer hose  24   c  is provided with a restrictor  62  having less restrictive dimensions, and the longest hose  24   d  is provided with no restrictor at all. 
   Using the restrictor  62  as an example, it will be seen that each restrictor comprises an annular, generally cylindrical body  64  having an internal passage  66  therethrough. Passage  66  has an inlet  68  at the upstream end of body  64 , an outlet  70  at the downstream end of body  64 , and a central throat  72  located between inlet  68  and outlet  70 . Throat  72  has a constant internal diameter, while inlet  68  tapers down from a maximum internal diameter at the upstream end of body  64  to a minimum internal diameter at its intersection with throat  72 . On the other hand, outlet  70  has an internal diameter that progressively expands as the downstream end of body  64  is approached. Inlet  68  only gradually tapers toward throat  72  while, on the other hand, outlet  70  abruptly expands as the downstream end of body  64  is approached. Thus, the rate of expansion of outlet  70  is considerably higher than the rate of convergence of inlet  68 . It has been found that a 10° taper for the internal sidewall of inlet  68  works well. In contrast, a 45° taper for the internal sidewall of outlet  70  is preferred. 
   Body  64  is provided with a continuous, circumferentially extending, enlarged lip  74  at the downstream end of body  64 . Immediately adjacent lip  74  is a continuous external collar  76  having an outside diameter that is slightly less than that of lip  74  but is greater than that of the remaining, reduced diameter portion  78  of body  64 . In a preferred embodiment, the restrictors are constructed from a synthetic resinous material. 
   It is contemplated that all restrictors associated with a machine will be of the same external dimensions, except for differences in length. Internally, the restrictors will be provided with different diameter throats  72  to afford greater or lesser restriction as the case may be, but the rate of convergence of the tapered inlet  68  will be the same in all cases, as will the rate of expansion of the outlet  70 . Accordingly, the lengths of the inlets  62  and outlets  70  will vary in accordance with different diameter throats  72 , as well as the overall length dimensions of the bodies. Thus, as will be noted comparing the restrictor  60  with the restrictor  62 , the diameter of throat  72  is smaller for restrictor  60  than restrictor  62 . This results in a longer inlet  68  and outlet  70  for restrictor  60  than for restrictor  62 . And, the overall length of restrictor  60  is greater than that of restrictor  62 . 
   As noted in  FIG. 7 , the restrictors are received within the nipples  38 . Preferably, the reduced diameter portion  78  of each restrictor has an outside diameter that is the same as or slightly less than the internal diameter of the nipple. On the other hand, the outside diameter of collar  76  is slightly greater than the inside diameter of nipple  38  such that the restrictor can be forced into the nipple and retained by a press fit between collar  76  and the inside surface of the nipple. Lip  74  has a greater outside diameter than the inside diameter of the nipple such that lip  74  serves as a stop to limit the extent of insertion of the restrictor into the nipple. This is illustrated in  FIG. 7 , for example. 
   From the foregoing, it should be apparent that using restrictors in accordance with the present invention provides a simple, yet highly effective solution to the problems associated with providing excess hose length simply to achieve uniform pressure at the widely dispersed distribution heads of the machine. Thus, a significant amount of unsightly clutter is avoided, while facilitating access to other components of the machine and reducing costs. Moreover, the restrictors need not be adjusted, are hidden from view, and are protected within the nipples  38 . 
     FIG. 2  shows a typical prior art machine wherein all of the primary supply hoses are of the same length in order to maintain uniform pressure at the distribution heads. Thus, all of the hoses in this machine, except for the two longest left and right hoses, are substantially longer than the corresponding hoses on implement  14  of the present invention. 
   The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.