Abstract:
A break-away apparatus for a boom arm is positioned at a joint between the main boom portion and the boom tip. The apparatus allows the boom tip to assume a neutral position and to pivot forward and rearward. The apparatus includes a first plate disposed at the joint, a second plate disposed at the joint, and a hinge assembly positioned between the first plate and the second plate. The hinge assembly includes a hinge pin having a longitudinal axis. The first and second plates are in a first position with respect to each other when the boom tip assumes the neutral position. The first and second plates are movable with respect to each other about the longitudinal axis. A torsion spring is configured to return the first and second plates to the first position after the first and second plates move from the first position.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 61/888,145, filed Oct. 8, 2013, entitled “BI-DIRECTIONAL BREAK-AWAY BOOM WITH TORSION SPRINGS AND ROTARY DAMPER” which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates generally to agricultural sprayers, and more particularly to a break-away boom arm for an agricultural sprayer. 
     2. Description of Related Art 
     A crop sprayer may be in the form of an agricultural vehicle or may be mounted to an agricultural vehicle. The crop sprayer may spray a fluid including herbicides, pesticides, and fertilizers on agricultural crops in a field. The fluid may be sprayed from nozzles mounted on a boom on the crop sprayer. Large agricultural sprayers typically have horizontal booms to allow for extensive spray coverage of crops in a field with a single travel pass. In some cases, booms have a length between about 20 and about 150 feet. 
     With conventional crop sprayers, an operator may drive the crop sprayer forward in a field. As the crop sprayer moves in the field, the boom (or more specifically, a boom tip) may impact an obstacle (such as a tree, power pole, fence or post, for example), or force may otherwise be applied to the boom. This impact or force may damage the boom, the boom tip and/or the obstacle. 
     In some commercially produced chemical application booms, the boom tips are configured to break away rearwardly as the sprayer moves forward. However, in some cases, such as when the sprayer travels backward, the boom encounters an obstacle wherein it is pushed forwardly. Many boom tips are not designed to break away forwardly; thus, the boom may sustain extensive damage. 
     SUMMARY 
     In one aspect, a break-away apparatus for a boom arm comprising a main boom portion and a boom tip is disclosed. The apparatus is positioned at a joint between the main boom portion and the boom tip. The apparatus allows the boom tip to assume a neutral position and to pivot to a forward position and to a rearward position with respect to the main boom portion. The apparatus comprises a first plate disposed at the joint, a second plate disposed at the joint, and a hinge assembly positioned between the first plate and the second plate. The hinge assembly comprises a hinge pin having a longitudinal axis. The first and second plates are in a first position with respect to each other when the boom tip assumes the neutral position. The first and second plates are movable with respect to each other about the longitudinal axis. A torsion spring is configured to return the first and second plates to the first position after the first and second plates move from the first position. 
     This summary is provided to introduce concepts in simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the disclosed or claimed subject matter and is not intended to describe each disclosed embodiment or every implementation of the disclosed or claimed subject matter. Specifically, features disclosed herein with respect to one embodiment may be equally applicable to another. Further, this summary is not intended to be used as an aid in determining the scope of the claimed subject matter. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The figures and the description that follow more particularly exemplify illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed subject matter will be further explained with reference to the attached figures, wherein like structure or system elements are referred to by like reference numerals throughout the several views. 
         FIG. 1A  is a top plan view of an exemplary boom arm in a forward break configuration, as if mounted on an implement traveling in direction T. 
         FIG. 1B  is a top plan view of the exemplary boom arm in a rearward break configuration, as if mounted on an implement traveling in direction T. 
         FIG. 2A  is a side elevation view of the exemplary boom. 
         FIG. 2B  is an enlarged view of the circle  2 B in  FIG. 2A . 
         FIG. 2C  is a top plan view of the area of the circle  2 B in  FIG. 2A . 
         FIG. 3A  is a top perspective view of the exemplary boom in a forward break configuration, as if mounted on an implement traveling in direction T. 
         FIG. 3B  is an enlarged view of the circle  3 B of  FIG. 3A . 
         FIG. 4A  is a top perspective view of the exemplary boom in a rearward break configuration, as if mounted on an implement traveling in direction T. 
         FIG. 4B  is an enlarged view of the circle  4 B of  FIG. 4A . 
         FIG. 5A  is an exploded perspective view of an exemplary breakaway joint in the boom of  FIGS. 1A-4B . 
         FIG. 5B  is a top plan view of the joint of  FIG. 5A . 
         FIG. 5C  is a side elevation view of the joint of  FIG. 5B . 
     
    
    
     While the above-identified figures set forth one or more embodiments of the disclosed subject matter, other embodiments are also contemplated, as noted in the disclosure. In all cases, this disclosure presents the disclosed subject matter by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this disclosure. 
     The figures may not be drawn to scale. In particular, some features may be enlarged relative to other features for clarity. Moreover, where terms such as above, below, over, under, top, bottom, side, right, left, etc., are used, it is to be understood that they are used only for ease of understanding the description. It is contemplated that structures may be oriented otherwise. 
     DETAILED DESCRIPTION 
     The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description. 
     A break-away assembly of the present disclosure allows a boom tip to break away to the rear or front of the agricultural vehicle without damaging the agricultural vehicle or the boom arm when the boom tip impacts an obstacle or when a sufficient force is otherwise be applied to the boom tip. Release of the boom tip diminishes the stress placed on the boom arm and mounting apparatus. 
     A boom arm with a bi-directional boom-tip break-away feature is described that can be used, for example, on liquid sprayers. A suitable liquid sprayer is disclosed in U.S. Patent Application Publication No. 2012/0237284, assigned to AGCO Corporation, and entitled “Boom fore and aft breakaway assembly,” the disclosure of which is fully incorporated by reference herein. Another suitable liquid sprayer is disclosed in U.S. Pat. No. 7,823,803, assigned to AGCO Corporation, and entitled “Integrated breakaway cylinder and method for constructing a boom assembly,” the disclosure of which is fully incorporated by reference herein. A boom arm of the present disclosure may be attached to a liquid sprayer by conventional means. 
     An exemplary break-away boom arm of the present disclosure allows the boom tip to hinge back or forward when coming in contact with an obstruction in the field. In one embodiment, the boom tip is connected to the main boom portion by a hinge assembly having torsion springs concentric with a hinge pin. The torsion springs bring the boom tip back to center from either forward or rearward movement. A rotary damper is used in an embodiment to control the speed at which the boom tip comes back into the neutral position. 
       FIG. 1A  is a top plan view of an exemplary boom arm  10  in a forward break configuration, with boom tip  12  pivoted forward from main boom portion  14 . In an exemplary embodiment, boom arm  10  is a truss assembly of aluminum pieces; boom arm  10  supports a plurality of liquid spray nozzles (not shown).  FIG. 1B  is a top plan view of boom arm  10  in a rearward break configuration, with boom tip  12  pivoted rearward from main boom portion  14 . The structure and operation of the break-away mechanism or apparatus  20  positioned at a joint between main boom portion  14  and boom tip  12  is further described below. 
       FIG. 2A  is a side elevation view of horizontally extending boom arm  10  in a neutral position (i.e., with boom tip  12  not pivoted forward or backward).  FIG. 2B  is an enlarged view of the circled area  2 B in  FIG. 2A , showing hinge assembly  22  of break-away mechanism  20 .  FIG. 2C  is a top plan view of the circled area  2 B in  FIG. 2A . In an exemplary embodiment, hinge assembly  22  is not normal or perpendicular with respect to the bottom surface  24  of boom arm  10  (which, when its associated sprayer is disposed on a horizontal surface, is also generally horizontal). Rather, hinge axis  25  of hinge assembly  22  is disposed at an acute angle alpha with respect to a line  26  that is perpendicular to generally horizontally extending bottom surface  24  of boom arm  10 . In an exemplary embodiment, alpha is between about 10 degrees and about 20 degrees, and is most suitably about 15 degrees. Because of this inclination, boom tip  12  becomes aligned slightly upward as well as forward (as shown in  FIG. 1A ) or rearward (as shown in  FIG. 1B ) relative to main boom portion  14  when pivoted on axis  25 . When the obstacle that caused the forward or rearward pivoting of boom tip  12  relative to main boom portion  14  is passed, gravity assists in returning boom tip  12  to the neutral position shown in  FIG. 2A . Other angles outside of the 10-20 degree range may be used, but smaller angles will not offer as much gravity assistance for the boom tip return to its unpivoted position, and larger angles will result in additional stresses on hinge assembly  22 . 
       FIG. 3A  is a top perspective view of boom arm  10  in a forward break configuration, the top plan view of which is shown in  FIG. 1A .  FIG. 3B  is an enlarged view of circled area  3 B in  FIG. 3A .  FIG. 4A  is a top perspective view of boom arm  10  in a rearward break configuration, the top plan view of which is shown in  FIG. 1B .  FIG. 4B  is an enlarged view of circled area  4 B in  FIG. 4A . In an exemplary embodiment, boom tip  12  includes end plate  28 , and main boom portion  14  includes end plate  34 . Hinge assembly  22  is positioned between end plates  28  and  34 . While the term “plate” is used, it is to be understood that plates  28  and  24  need not be flat. On one side of the joint between main boom portion  14  and boom tip  12 , end plate  28  is disposed at an end of boom tip  12 . On the other side of the joint between main boom portion  14  and boom tip  12 , end plate  34  is disposed at an end of main boom portion  14 . 
       FIGS. 5A-5C  show exploded, top plan and side elevations views, respectively, of break-away mechanism  20 . Please note that the orientation of  FIGS. 5A-5C  is opposite that of  FIGS. 1A-4B . In particular, in  FIGS. 5A-5C , end plate  34  of main boom portion  14  is shown on the left, and end plate  28  of boom tip  12  is shown on the right. Upper and lower pin holding brackets  30  and  31 , respectively, extend from end plate  28 ; upper and lower pin holding brackets  32  and  33 , respectively, extend from end plate  34 . Upper pin holding bracket  30  includes upper pin sleeve  37 , and lower pin holding bracket  31  includes lower pin sleeve  39 . Central brackets  36  and  38  extend from end plate  34  and fixedly support central pin sleeve  40 . When assembled as seen in  FIG. 5C , upper pin sleeve  37 , central pin sleeve  40  and lower pin sleeve  39  define hinge axis  25  and support hinge pin  42 . In an exemplary embodiment, top end  44  of hinge pin  42  includes a plate  46  that is secured to upper pin holding bracket  32  (with, for example, bolt  48 , nut  50 , and cooperative apertures  48   a  and  48   b  (not shown) on plate  46  and bracket  32 , respectively, though other fastening arrangements can also or alternatively be used). Thus, hinge pin  42  is fixed to end plate  34 . Pin sleeves  37 ,  39  are dimensioned to allow pin sleeves  37 ,  39  to rotate around hinge pin  42  about hinge axis  25 . 
     Rotary damper  56  limits free rotation of pin sleeves  37 ,  39  relative to hinge pin  42 . Housing  60  of rotary damper  56  is fixed to bracket  58  of end plate  28  of boom tip  12  (with, for example, screws  62 , though other fasteners can also or alternatively be used). Stud  54  of rotary damper  56  has a contour that fits closely within a complimentary bore  51  (see  FIG. 5A ) in a lower end  52  of hinge pin  42 . As boom tip  12  (and therefore end plate  28 ) moves with respect to main boom portion  14 , housing  60  moves with boom tip  12 . However, stud  54  of rotary damper  56  is fixed to hinge pin  42 , which in turn is fixed to end plate  34  of main boom portion  14 . Rotary damper  56  is configured to control the rate at which housing  60  and stud  54  return to the neutral position (i.e., where boom tip  12  is unpivoted relative to main boom portion  14 ). Rotary damper  56  thereby controls the rate at which the attached boom tip  12  and main boom portion  14  return to the neutral configuration (i.e., unpivoted relative to each other). Known rotary dampers may be used, including, for example, model X-CRD, commercially available from Kinetrol LTD of Tulsa, Okla. 
     When break-away mechanism  20  is assembled as shown in  FIG. 5C , upper torsion spring  64  concentrically surrounds hinge pin  42  and is positioned between upper pin holding bracket  32  of plate  34  and upper pin holding bracket  30  of plate  28 . Upper torsion spring  64  includes upper end  66  and lower end  68 . Upper end  66  is held in place by peg  70  on a bottom surface of pin holding bracket  32 . Lower end  68  is held in place by peg  72  on a top surface of pin holding bracket  30 . Lower torsion spring  74  concentrically surrounds hinge pin  42  and is positioned between lower pin holding bracket  33  of plate  34  and lower pin holding bracket  31  of plate  28 . Lower torsion spring  74  includes upper end  76  and lower end  78 . Upper end  76  is held in place by peg  80  on a bottom surface of pin holding bracket  31 . Lower end  78  is held in place by peg  82  on a top surface of pin holding bracket  33 . 
     In an exemplary embodiment, each of torsion springs  64 ,  74  is a helical coil spring that is positioned coaxially with hinge pin  42  so that an axis of the coil coincides with hinge axis  25 . Torsion springs  64 ,  74  are arranged with respect to end plates  28 ,  34  so that movement of the plates  28 ,  34  about hinge axis  25  in one direction (such as with a forward break shown in  FIG. 3B  or a rearward break shown in  FIG. 4B ) will twist the coil of one of the torsion springs  64 ,  74  tighter; movement of the plates  28 ,  34  about hinge axis  25  in the opposite direction will twist the coil of the other torsion spring  64 ,  74  tighter. 
     Keeping in mind that the orientation of  FIGS. 5A-5C  is opposite the orientation of  FIGS. 1A-4B , it is evident that a forward break such as shown in  FIG. 3B  causes upper torsion spring  64  to twist more tightly, thereby increasing the bending moments in the coil of upper torsion spring  64 . The recovery force of upper torsion spring  64  thus urges ends plates  28 ,  34  back into the neutral position shown in  FIG. 5C . Similarly, a rearward break such as shown in  FIG. 4B  causes lower torsion spring  74  to twist more tightly, thereby increasing the bending moments in the coil of lower torsion spring  74 . The recovery force of lower torsion spring  74  thus urges ends plates  28 ,  34  back into the neutral position shown in  FIG. 5C . In another embodiment, the arrangement of upper and lower torsion springs  64 ,  74  may be changed so that recovery from a forward break is achieved by lower torsion spring  74  and recovery from rearward break is achieved by upper torsion spring  64 . 
     Although the subject of this disclosure has been described with reference to several embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure. While a particular configuration of break-away mechanism  20  is described, it is contemplated that variations may be made. For example, while a particular arrangement of elements is shown, it is contemplated that parts of a break-away mechanism may be assembled otherwise. For example, while the illustrated embodiment shows a structure in which certain elements are attached to main boom portion  14  and other elements are attached to boom tip  12 , it is contemplated that these attachments may be reversed.