Abstract:
In orchards or fields of grape vines, weeding in inter-plant spaces may be performed with a mechanical weeder. The weeder may include a frame configured to be propelled by a motorized vehicle. A rotatable weeder unit may be pivotally connected to a pivot arm attached to the frame and a spring may be connected to hold the rotatable weeder unit in a nominal pivotal position relative to the frame responsively to a force exerted by the spring. When encountering a producing plant, the weeder unit may deflect away from the plant thereby precluding damage to the plant.

Description:
RELATED APPLICATIONS 
       [0001]    The application claims the benefit of US Provisional Application No. 61/345,241 filed on May 17, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to agricultural systems for eliminating undesired vegetation in regions near or adjacent to fruit or nut bearing plants. 
         [0003]    In a typical agricultural setting in which fruit or nuts may be produced, plants are arranged in rows with substantially equal spacing between the rows. Spaces between the rows may be wide enough to allow passage of machinery such a tractors or trucks. 
         [0004]    Undesirable vegetation, i.e., weeds, may grow in these spaces. These weeds may be periodically removed with chemicals or motorized machinery such as mowers, cultivators or tillers. Such weed removal operations may be relatively easy to perform in most areas of the inter-row spaces. However, in certain regions of the inter-row spaces, in close proximity to the fruit or nut bearing plants, there is a risk that conventional weed removal may result in damage to the plants. Thus a farmer may forego weed removal in these close proximity areas. 
         [0005]    Ironically, weeds growing in these close proximity areas may have a particularly deleterious effect on productivity of the fruit or nut bearing plants. In other words, a weed that is close to a plant may absorb more nutrients and moisture from a productive plant&#39;s roots than a weed that is far from the plant. 
         [0006]    As can be seen, there is a need for a system that may be employed to remove weeds from inter-row spaces in areas that are in close proximity to producing fruit or nut bearing plants. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect of the present invention, a mechanical weeder may comprise a frame configured to be propelled by a motorized vehicle; a rotatable weeder unit pivotally connected to a pivot arm attached to the frame; and a spring connected to hold the rotatable weeder unit in a nominal pivotal position relative to the frame responsively to a force exerted by the spring. 
         [0008]    In another aspect of the present invention, a deflectable weeder assembly attachable to a motorized vehicle may comprise a pivot arm fixedly attachable to the vehicle; a wheel freely rotatable about a wheel axis; and a spring-biased wheel support rotatable about the pivot arm, the wheel being connected to the spring-biased wheel support with the wheel axis being displaced from the pivot arm. 
         [0009]    In still another aspect of the invention, a method for removing weeds from rows of fruit or nut bearing plants may comprise the steps of inserting a portion of a wheel into a berm adjacent one of the rows; pushing the wheel along the berm with a motorized vehicle while allowing the wheel to freely rotate about its wheel axis and while maintaining the wheel axis within 10° of vertical; maintaining the wheel axis in a nominal position relative to the vehicle with a predetermined spring-bias force whenever the wheel is not subjected to wheel contact force that is less than the predetermined force; and allowing the wheel to deflect from the nominal position whenever the wheel contact force exceeds the predetermined spring-bias force. 
         [0010]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of an agricultural setting in which the invention has utility; 
           [0012]      FIG. 2  is a perspective view of a mechanical weeder in accordance with an embodiment of the invention; 
           [0013]      FIG. 3  is a perspective view of a weeding assembly in accordance with an embodiment of the invention; 
           [0014]      FIG. 4  is an elevational diagram of an operational feature of the weeding assembly of  FIG. 3 ; 
           [0015]      FIG. 5  is a plan diagram of an operational feature of the weeding assembly of  FIG. 3 ; 
           [0016]      FIG. 6  is second elevational diagram of an operational feature of the weeding assembly of  FIG. 3 ; 
           [0017]      FIG. 7  is an elevation view of a weeding assembly in accordance with another embodiment of the invention; and 
           [0018]      FIG. 8  is an end view of the weeding assembly of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0020]    Various inventive features are described below that can each be used independently of one another or in combination with other features. 
         [0021]    Broadly, embodiments of the present invention generally provide a system for mechanically removing weeds in inter-plant spaces between fruit of nut bearing plants. More particularly, the present invention provides for such weed removal in areas that are adjacent the plants without producing physical damage to the plants. 
         [0022]    Referring now to  FIG. 1 , an exemplary agricultural setting in which the invention may have utility may be a grape vineyard  100 . The vineyard  100  may comprise plants  102 , arranged in rows  104 . The plants  102  may be surrounded by berms  106 . Space between the rows  104  may be referred as inter-row space  105 . 
         [0023]    Referring now to  FIGS. 2 and 3 , there may be seen an exemplary embodiment of a mechanical weeder  10 . The weeder  10  may be employed to remove weeds from the berms  106  of the vineyard  100  of  FIG. 1 . The weeder  10  may be attached to a front end of a tractor (not shown) and pushed between the rows  104  of the vineyard  100 . 
         [0024]    The weeder  10  may comprise a frame  12 , wheels  14  and one or more weeding assemblies  16 . Optionally, a width adjuster  18  may be provided so that lateral spacing between the weeding assemblies  16  may be altered to adapt the weeder  10  for use in vineyards having various spacing between their respective rows  104 . 
         [0025]    The weeder assembly  16  may comprise a rotatable weeder unit or weeder wheel  20 , a wheel mounting arm  22 , a pivot arm  24  and a connector arm  26 . The pivot arm  24  and the connector arm  26  may be fixedly attached to the frame  12 . A support member  28  may be rotatably attached to the pivot arm  24 . A connecting link  30  may interconnect the support member  28  with a telescoping spring-biased arm  32  at a free end  32 - 1  of the arm  32 . A fixed end  32 - 2  (see  FIG. 2 ) of the arm  32  may be fixedly connected to the arm  26  which, in turn, may be fixedly connected to the frame  12 . A compression spring  34  may be connected to spring bias the arm  32  into a nominal extended position in which a stop  36  may be engaged with arm  26 . An adjustment collar  37  may be provided for precompressing the spring  34  to produce a desired force between the stop  36  and the arm  26 . 
         [0026]    Various operational features of the weeder  10  may be understood by referring to  FIGS. 4 ,  5  and  6 . In  FIG. 4 , it may be seen that the weeding wheel  20  may be progressively pushed through the berm  106  while being submerged under some soil of the berm  106 . For example, the weeding wheel  20  may be submerged a distance X which may be about 2 inches. As the weeding wheel  20  passes through the berm  106 , frictional engagement between the wheel  20  and the soil may cause the wheel  20  to rotate on an axis  20 - 1 . Rotation of the wheel  20  may allow the wheel  20  to be pushed through the soil with relative ease. 
         [0027]    As the wheel  20  strikes a weed plant  103 , it may sever its upper foliage  103 - 1  from its roots  103 - 2  thus rendering the weed plant  103  unviable. It may be noted that the fruit-bearing plant  102  may have its roots  102 - 2  a distance Y below a top surface of the berm  106 . The distance Y may be about 12 to 18 inches. Consequently, the weeding wheel  20  may pass over the roots  102 - 2  without contacting or damaging them. 
         [0028]    Referring now particularly to  FIG. 5 , it may be noted that when the weeding wheel  20  may strike a stem  102 - 1  of the plant  102 , the wheel  20  may deflect away from the stem  102 - 1  as it rolls around the stem. In  FIG. 5 , a line  108  may represent a nominal position of the axis  20 - 1  of the wheel  20  as the weeder  10  may be pushed through one of the rows  104 . It may be seen that when the wheel  20  is not in contact with any of the plants  102 , the axis  20 - 1  of the wheel  20  may pass along the nominal line  108 . As the wheel  20  comes close to one of the plants  102 , the wheel  20  may be deflected so that its axis  20 - 1  may no longer be on the nominal line  108 . (Such deflection may be accommodated by the spring-biased structural features described above with respect to  FIG. 2 ). Deflection may begin before actual contact between the wheel  20  and the plant  102 . This may occur because a wave  110  of disturbed soil see  FIG. 6 ) may be pushed ahead of the wheel  20  as the weeder  10  progresses through the inter-row space  105 . The wave  110  may produce back-pressure between the wheel  20  and the plant  102  thereby causing the wheel  20  to begin deflecting. Consequently, the plants  102  remain undamaged during operation of the weeder  10 . 
         [0029]    The weeder  10  may be advantageously operated so that a distance between Z between the lines  104  and  108  is less than a radius of the wheel  20 . When operated in this manner, weed cutting action of the weeder  10  may overlap the row line  104 . Consider, for example, an exemplary embodiment in which a diameter of the wheel  20  may be 18 inches. The weeder  10  may be adjusted in width and pushed so that the axis  20 - 1  of the wheel  20  may pass along the nominal line  108  at a distance Z of about 14 inches, thereby providing overlapping weed cutting for a distance Z 1  of about 4 inches beyond the row line  104 . 
         [0030]    When operated with an overlap distance Z 1  of about 4 inches, the weeder  10  may be pushed through one of the inter-row spaces  105  at a rate of about 4 miles per hour (mph) with a 40 horsepower (HP) tractor. If higher ground speed is desired, the overlap distance Z 1  may be reduced. 
         [0031]    In some soil conditions, it may be desirable to orient a plane of the wheel  20  into a non-horizontal position as shown in  FIG. 6 . The wheel  20  may be oriented so that its axis  20 - 1  may be positioned at an angle A relative to vertical and so that the axis  20 - 1  may be tilted toward a direction of travel of the weeder  10  (indicated by the arrow  50 ). In an exemplary embodiment, the angle A may be between 0° and about 10°. As the wheel  20  moves through the berm  106 , the wave  110  of disturbed soil may develop and progress with the wheel  30 . The wave  110  may advantageously produce back-pressure against the wheel  20  when the wave strikes one of the plants  102 , thus providing force that may results in backward deflection of the wheel  20  and precluding damage to the plant  102 . 
         [0032]    Referring back to  FIG. 2 , it may be seen that variation of wheel-plane orientation may be achieved by rotating the arm  22  relative to the support  28  within an adjustable bracket  29 . 
         [0033]    Referring now to  FIGS. 7 and 8 , another exemplary embodiment of a weeder assembly  60  may comprise, a deflecting tiller assembly  62  mounted on an arm  64  that may be rotatably connected to a pivot arm  66  in a manner similarly to the weeder assembly  16  of  FIGS. 1 and 2 . The tiller assembly  62  may comprise tiller tines  62 - 1  driven by a hydraulic motor  62 - 2  and a shield wheel  62 - 3 . As may be seen particularly in  FIG. 7 , the tiller tines  62 - 1  may spin within a circle having a diameter D. The shield wheel  62 - 3  may have a larger diameter, D+C. It can be seen that, as the shield wheel  62 - 3  may come into contact with a fruit bearing plant such as an apple tree (not shown), the tiller assembly  62  may be deflected away from the tree in a manner similar to that of the weeder wheel  20  of  FIGS. 1 and 2 . The tiller tines  62 - 1  may never come into contact with the tree and thus may never inflict damage to the tree. 
         [0034]    The weeder assembly  60  may be provided with a hydraulic cylinder  68  which may be employed to vary angularity of a rotational axis of the tiller tines  62 - 1  from an angle of about 30° above horizontal to about 15° below horizontal. 
         [0035]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.