Abstract:
An auger for digging holes that minimizes the amount of loose dirt excavated in and around the dug hole. The auger comprises an elongated shaft body whose axial longitudinal center is disposed in a parallel offset position from the axial engagement line of orientation with the driving source for rotationally driving the auger. The shaft body of the auger revolves in an eccentric lateral orbit as the auger rotates which digs the hole by pushing and widening the dirt in the hole rather than cutting and scraping. The distal end of the auger has a tapered configuration for initial penetration into the ground. The eccentric movement of the shaft body of the auger helps to compact the walls of the hole being dug.

Description:
RELATED APPLICATIONS 
     The present non-provisional patent application claims priority benefit of an earlier-filed provisional patent application of the same title, Ser. No. 61/392,616, filed Oct. 13, 2010. The identified earlier-filed application is hereby incorporated by reference into the present application. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to digging equipment, and in particular, augers for digging holes in the ground. More particularly, the present invention relates to drilling post holes for fence posts or utility poles. 
     BACKGROUND OF THE INVENTION 
     A variety of methods are utilized to produce a post hole, involving both mechanized and non-mechanized means. Mechanized post hole diggers generally comprise a rotating auger having helical flighting and a cutting head to aid in loosening the soil to be excavated. As the auger rotates, the loosened soil is conveyed out of the hole by the screw-like movement action of the helical flighting formed into the auger. While the helical flighted type of auger effectively produces a hole, it leaves loose soil at the bottom of the hole and spatters the soil at the top of the hole surrounding it. It is typical for some of the excavated soil deposited around the top of the hole by the auger fighting to fall back into the hole during post installation. This requires a further step in removing the loose soil from the bottom of the post hole before a post is planted into the newly dug post hole. 
     An installed post should be stabilized to withstand and support a load, so it is desirable to compact the earth walls forming the post hole so that the post can be solidly planted to limit future settling of the post. In order to achieve a properly compacted hole, the loose soil must either be first removed by hand or compacted directly in place. Additionally, when setting posts in concrete, the soil that is excavated from the hole is replaced by concrete which requires the overburden soil to be removed after the post is set. Ensuring the soil is properly compacted and removing the excavated overburden soil can be very time consuming and labor intensive. 
     Although the auger&#39;s helical flighting effectively scrapes away earth to form the excavated post hole, the cutting action disturbs the stability of the hole wall and leaves the remaining wall subject to crumbling and degradation. Occasionally, it is advantageous to enhance the stability of the hole&#39;s wall by compacting the wall&#39;s surface. This action requires a further step after the use and retraction of the helical flighted auger, and the removal of the loose soil from the hole. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an auger that effectively digs a post hole while limiting the amount of loose soil generated from the digging of the post hole. An embodiment of the auger of the present invention comprises an elongated shaft body having a tapered end. The lateral surface of the shaft body is without helical flighting elements such that the ground in which the auger is inserted is effectively pushed outwardly to form the post hole, rather than excavated. The inventive auger limits the generation of loose soil which would otherwise remain in the post hole or be conveyed out of the post hole. 
     It is another embodiment of the present invention to provide an auger that imparts a compacting action against the post hole wall as the post hole is dug. 
     An embodiment of the auger of the present invention comprises an elongated shaft having a tapered end. The elongated shaft has a central longitudinal axis of the auger offset from the axial line of engagement with the rotational driving source of the mechanized implement to which it is connected. This configuration causes the auger to rotate in an eccentric rotational orbit as it is driven by the mechanized source. The auger digs the post hole by poking through the soil with the tapered end and pushing sideways against the earth though the back and forth lateral pushing forces by the shaft body. 
     It is another embodiment of the present invention to provide a method by which to dig a post hole that minimizes the amount of loose dirt generated by the creation of the post hole. 
     It is another embodiment of the present invention to provide a method by which the walls of a post hole are compacted as the post hole is dug. 
     These and other important features of the present invention are more fully described in the section titled DETAILED DESCRIPTION OF THE INVENTION, below. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following description with reference to the accompanying drawings, in which: 
         FIG. 1  is view in side elevation of an embodiment of the auger of the present invention. 
         FIG. 2  is a view similar to  FIG. 1  but rotated 90° to the left about the vertical axis. 
         FIG. 3  is a view in side elevation of another embodiment of the auger. 
         FIG. 4  is a cross-sectional view of an embodiment of the auger in side elevation taken along lines  4 - 4  in  FIG. 3 . 
         FIG. 5  is a cross-sectional view taken along lines  5 - 5  in  FIG. 3 . 
         FIG. 6  is a view similar to  FIG. 5  but rotated 90° clockwise. 
         FIG. 7  is a view similar to  FIG. 6  but rotated 90° clockwise. 
         FIG. 8  is a view similar to  FIG. 7  but rotated 90° clockwise. 
         FIG. 9  is a cross-sectional view taken along lines  9 - 9  in  FIG. 3 . 
         FIG. 10  is a view similar to  FIG. 9  but rotated 90° clockwise. 
         FIG. 11  is a view similar to  FIG. 10  but rotated 90° clockwise. 
         FIG. 12  is a view similar to  FIG. 11  but rotated 90° clockwise. 
         FIG. 13  is a perspective view of an embodiment of the auger penetrating the earth. 
         FIG. 14  is a cross-sectional view taken along lines  14 - 14  in  FIG. 13 . 
         FIG. 15  is a view similar to  FIG. 14  but rotated 90° clockwise pursuant to rotation of the auger as drilling proceeds. 
         FIG. 16  is a view similar to  FIG. 15  but rotated 90° clockwise pursuant to further rotation of the auger as drilling proceeds. 
         FIG. 17  is a view similar to  FIG. 16  but rotated 90° clockwise pursuant to further rotation of the auger as drilling proceeds. 
         FIG. 18  is a cross-sectional view taken along lines  18 - 18  in  FIG. 3 . 
         FIG. 19  is a view in side elevation of another embodiment of the auger of the present invention. 
         FIG. 20  is a view in side elevation of another embodiment of the auger of the present invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to the drawing figures, an embodiment of the inventive auger  10  is generally shown in  FIG. 1 . Auger  10  is adapted for connection to drive unit  12  which is commonly provided by a carrier machine, such as a skid steer loader (not shown), through means generally known to those having skill in the art. For example, auger attachment may be connected by bolting to drive spindle  14  of drive unit  12 .  FIG. 1  shows auger collar  15  as a female portion which receives male portion drive spindle  14  (hidden from view). Common drive spindle sizes include but are not limited to 1⅝ inch round, 2 inch round, 2 9/16 inch round, 2 inch hex, 2½ inch hex, 2⅝ inch hex, 4 inch square, and 6 inch square. The carrier machine provides a means to maneuver the auger into place and applies the hydraulic equipment required to lower the auger into the ground and retract it. The drive unit  12  is typically powered hydraulically or through mechanical means with the carrier machine being the source of power. The carrier machine can also be a tractor, excavator, backhoe or other suitable machine. 
     As shown in  FIG. 1 , auger  10  is comprised of elongated shaft column  16 , auger shaft body  18 , tapered shaft portion  20  and auger bit tip  22 . The proximal end of elongated shaft column  16  connects through auger collar  15  to drive spindle  14  by bolting or other appropriate connector members. Elongated shaft column  16  runs the span of the auger and connects at its distal end to auger tip  22 . Shaft column  16  may be comprised of a tubular metal but it can be of any number of different shapes or materials, for example an oval cross-sectional shape. A bit point adapter generally indicated at  24  is attached to the distal end of shaft column  16 . Bit point adapter  24  is typically produced from cast or forged steel and may be configured with an internal socket or threads that allow the bit tip  22  to be attached. Bit tip  22  can be of any type normally used with augers of all types and is typically a cast or forged part that has a single or double helical flight shape wrapped around a cone shaped base. The leading edges of the helical shape are designed to engage the material being dug through and aid in penetration. Auger  10  is connected to the drive unit  12  such that shaft column  16  and bit tip  22  are oriented in axial alignment engagement with drive spindle  14 . 
     Auger shaft body  18  comprises a cylindrical member  26  which extends along a substantial portion of shaft column  16  as shown in  FIG. 1 . Cylindrical member  26  is placed around and connected to shaft column  16  such that the central longitudinal axis of cylindrical member  26  runs parallel to, but offset from the longitudinal axis of shaft column  16 . When viewing  FIG. 1  in comparison to  FIG. 2 , it can be seen that the front edge of cylindrical member  26  is connected to shaft column  16  (by welding for example) leaving the back edge of cylindrical member  26  spaced apart from shaft column  16 . This configuration effectively positions the central longitudinal axis of cylindrical member  26  offset from the central longitudinal axis of shaft column  16  as further seen in  FIG. 4 . 
     Tapered shaft portion  20  comprises a cylindrical cone member  28 . The preferred embodiment is a hollow cone made from steel but it can be fabricated from any number of materials or be solid instead of hollow. Cone member  28  is attached (by welding for example) such that the central axis of the cone lies transverse to the longitudinal axis of shaft column  16 , placing cone member  28  at an angle with cylindrical member  26  as shown in  FIG. 4 . The amount of angle between cylindrical cone member  28  and shaft column  16  varies depending upon the different auger bit diameter used. Near the area of intersection between the cone member  28  and cylindrical member  26  is a reinforcing plate  30  as shown in  FIG. 4 . At the top of cylindrical member  26  is another reinforcing plate  32 . These reinforcing plates provide for extra strength in these areas and prevent soil from becoming entrapped in the bit. Depending upon the construction method of the cylindrical cone and cylinder, these reinforcing plates can vary in size or necessity. 
     Auger  10  can also be made of a single integrated piece as opposed to welding together the individual components above described. Also, auger shaft body  18  may comprise an elliptical configuration, as opposed to a cylindrical configuration, so long as the central longitudinal axis of the overall shaft body is offset from the axial line of engagement of shaft column  16  with drive spindle  14 . 
     The external surface of auger  10  can comprise a hard facing or provided with raised elements such as spiral or checkered hard facing  34  as shown in  FIG. 3 . This provides a durable wear surface and increases the auger&#39;s useful life. Also, auger  10  can terminate simply in tapered shaft portion  20  without an auger bit tip  22  when soil conditions permit it. In such cases, tapered shaft portion  20  may simply terminate in a narrow point or the like. 
     The configuration of auger  10  as described confers an eccentric orbital rotation as shown in  FIGS. 5-12 . As first seen in  FIG. 5 , shaft column  16  engages drive spindle  14  to provide an axial alignment engagement with drive unit  12 . Cylindrical member  26  is connected to shaft column  16  such that the central longitudinal axis of cylindrical member  26  is offset from shaft column  16 . Cylindrical member  26  is shown in the figures as being connected to shaft column  16  through weldment  27 . The attachment configuration creates an opposing auger engagement surface  36  on cylindrical member  26 . As drive spindle  14  rotates to drive auger  10  90° as shown in  FIG. 6 , opposing auger engagement surface  36  moves in an eccentric orbit. It can be seen in  FIGS. 7 and 8  that the displacement effect of opposing auger engagement surface  36  revolves with the rotation of auger  10 . 
     Similarly, cone member  28  is connected to shaft column  16  such that the central axis of cone member  28  lies at an angle to shaft column  16  as shown in  FIG. 4 . This creates an opposing auger engagement surface  38  on cone member  28 . As auger  10  rotates to drive auger  10  90° as shown in  FIG. 10 , opposing auger engagement surface  38  moves in an eccentric orbit. It can be seen in  FIGS. 11 and 12  that the displacement effect of opposing auger engagement surface  38  revolves with the rotation of auger  10 . 
       FIGS. 13-17  show the effective operation of auger  10  as it penetrates into the ground  40  in digging a post hole  42 . As taper shaft portion  20  first penetrates into the ground  40  as shown in  FIG. 14 , opposing engagement surface  38  pushes laterally outwardly against ground  40  to begin to create a widening of the post hole at the relative 12:00 position shown. Because the outer surface of tapered shaft portion is without helical flighting, the creation of loose soil is minimized and remains intact in the walls of the widening post hole. In  FIG. 15 , as auger  10  rotates 90°, opposing engagement surface  38  moves along dirt wall  44  of post hole  42  to the 3:00 position. Because cone member  28  rotates in an eccentric orbit, opposing engagement surface  38  pushes outwardly against dirt wall  44  to effectively widen post hole  42  along the arc between the 12:00 position and the 3:00 position. It can be seen that an area already passed over by opposing engagement surface  38  from the previous position shown in  FIG. 14  effectively forms developing post hole  42 . In  FIG. 16 , as auger  10  rotates a further 90°, opposing engagement surface  38  moves along dirt wall  44  of post hole  42  to the 6:00 position, effectively widening post hole  42  along the arc between the 3:00 position and the 6:00 position. In  FIG. 17 , as auger  10  rotates yet a further 90°, opposing engagement surface  38  moves along dirt wall  44  of post hole  42  to the 9:00 position, effectively widening post hole  42  along the arc between the 6:00 position and the 9:00 position. As auger  10  continues to rotate and is driven down by drive unit  12 , cylindrical member  26  descends down into post hole  42  to contribute to the widening action begun by cone member  28  until the appropriate depth for post hole  42  is reached. The eccentric lateral orbit about which auger  10  revolves effectively causes dirt wall  44  to be expanded as auger shaft body  18  and tapered shaft portion  20  rotate in creating post hole  42 . Also, the back and forth engagement of auger shaft body  18  against dirt wall  44  acts to compact dirt wall  44  and the lateral soil area to provide a post hole having substantial structural integrity. Furthermore, the generation of loose soil around the entry point of the auger is minimized. 
     In another embodiment of the invention, auger  50 , shown in  FIG. 19 , which otherwise has a structure similar to auger  10 , comprises a cylindrical cone member  52  having helical flighting  54  formed into its outer surface. The helical flighting  54  aids in cutting and scraping dirt in initial penetration of the auger. As auger  50  continues to push through the dirt in forming the hole, cylindrical member  56  moves in an eccentric orbit to aid in compacting the wall of the formed hole. 
     In yet another embodiment of the invention, auger  60 , shown in  FIG. 20 , which otherwise has a structure similar to auger  10 , comprises a bit tip  62  having additional cutting teeth  64 . The cutting teeth  64  aids in cutting and scraping dirt in initial penetration of the auger. 
     In yet another embodiment of the invention, the auger can comprise a unitary shaft body, rather than joining together a separate cylinder member attached to shaft column. In other words, referring to  FIG. 4 , cylinder member  26 , shaft column  16  and cone member  28  could instead comprise a unitary piece. The unitary piece would attach to the drive unit  12  and drive spindle  14  in the same manner such that the axial center of the auger would be disposed in a parallel offset position from the axial line of engagement of the auger with the drive unit as generally shown in  FIGS. 1-4 .