Abstract:
The present invention relates to post hole diggers. In particular, the present invention describes a post hole digger that constructs uniform diameter holes. The post hole digger of the present invention is comprised of a pair of handles, digging scoops and a hinge bracket. The hinge bracket translates the movement of the handles into movement of the scoops. The hinge bracket restricts the movement of the handles as digging occurs, allowing for the construction of a relatively straight-sided post hole, essentially removes the tapering of a hole as the hole becomes deeper.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The following application is a continuation-in-part of U.S. patent application Ser. No. 09/903,737 filed Jul. 7, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to hole diggers. In particular, the invention describes a post hole digger that makes uniform diameter holes.  
         BACKGROUND OF THE INVENTION  
         [0003]    To utilize the post hole diggers generally in use, the hole digger is thrust into the ground and the handles are pulled apart to close the blades and scoop out the dirt. As the hole becomes deeper, the upper portion of the hole becomes progressively wider and larger in diameter. A three-foot deep hole made with a traditional hole digger with a closed blade having an+ approximate diameter only five inches must be opened up ten to eleven inches at the top. The hole created will be tapered which creates a lack of ground support when concrete or similar fill material is used to keep a post or pole in position. The instant invention enables the digging of post holes of essentially uniform diameter from ground surface level to the bottom of the hole.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is able to dig a hole without appreciably enlarging the upper section of the hole. The present device is comprised of a pair of handles, two metal scoops and a hinge bracket. In an alternative embodiment, the device may comprise two unitary pieces incorporating the handle and scoop into one unit with the unitary pieces joined by a hinge bracket. In another embodiment, each scoop is contiguous with a hinge bracket section, forming one piece. The hinge bracket is designed to limit the movement from the elongated handles and to translate the movement to the scoops. In the most preferred embodiment, the handles slightly cross in front of each other while in the open scoop position and open to form two parallel straight lines when the scoops are closed.  
           [0005]    In a preferred embodiment, the scoops are joined together to provide strength and limitation of movement. The digging scoops can be joined together by a bolt or, in a preferred embodiment, one of the scoops may have a fixed protrusion fitted into a slot formed in the second scoop to allow a sliding movement of the first scoop providing a more secure hold on dirt, soil or gravel when the scoops are closed. The hinge bracket is positioned near the midpoint of the pair of handles or, alternatively, between the midpoint of the handles and the top of the digging scoops. The bracket hinge limits the movement of the handles and translates the handle movement to the digging scoops. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1A shows a side view of an embodiment of the post hole digger in which a bolt holds the scoops together.  
         [0007]    [0007]FIG. 1B shows a side view of a preferred embodiment of the post hole digger.  
         [0008]    [0008]FIG. 2 shows a top cross section of the hinge bracket.  
         [0009]    [0009]FIG. 3A shows the scoops in a preferred embodiment slidably attached using a bolt-slot sliding union.  
         [0010]    [0010]FIG. 3B depicts a pair of unattached scoops.  
         [0011]    [0011]FIGS. 4A and 4B show side views of alternative embodiments of the post hole digger where each scoop is contiguous with a hinge bracket section, forming one piece.  
         [0012]    [0012]FIG. 4C shows a front view of the alternative embodiment shown in FIG. 4B, illustrating the location of the handles at the open position of the scoops.  
         [0013]    [0013]FIG. 5 shows a front view of an embodiment of the groundbreaking edge of the digging scoop.  
         [0014]    [0014]FIGS. 6A and 6B show the post hole digger of the instant invention and a prior art post hole digger, respectively, in operation digging a hole. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    The preferred embodiment of the present invention will now be described with reference to accompanying drawings. It will nevertheless be understood that no limitations of the scope of the invention is thereby intended, such alterations as scale of the parts, materials used, position of the hinge bracket, color or weight which would fall within the spirit and the scope of the invention described herein.  
         [0016]    [0016]FIG. 1A shows a side view of one embodiment of the post hole digger  14 . The post hole digger  14  is comprised of two handles  8  approximately four to six feet long with a diameter of approximately one inch. Blades  12   a  and  13   a  of scoop  28  are fixedly attached at one end of one of each handle  8 . The handles  8  are joined by a hinge bracket  9  attached to the two handles. The hinge bracket  9  has a pin  7  that rotates to translate the motion applied to the handles  8  into movement of the scoops  28  allowing the opening and closing of the scoops  28 . In a preferred embodiment, the hinge bracket is located at a midpoint on the handles with the midpoint defined as the point midway between the top  29  of scoop  28  and the top of the handles. In an alternative preferred embodiment, the hinge bracket  9  may be located between the midpoint and the top of the scoops. In the embodiment shown in FIG. 1A, the scoops are securely joined together by a bolt  29 . In the present invention it is not necessary to have the scoop joined but it is a preferred embodiment to provide strength and restrain movement. It should be recognized that the handle/scoop component can be fabricated into a single unitary part, such as by forging, with two such unitary parts joined using hinge bracket  9  and the scoop attachment bolt  29  noted supra.  
         [0017]    [0017]FIG. 1B shows an alternative preferred embodiment of the post hole digger  14 . As in FIG. 1A the device has a pair of handles  8 , two digging scoops  12  and  13  and a hinge bracket  9 . The location and function of the hinge bracket  9  is as in FIG. 1A. At the end of each handle  8  a scoop blade  12  or  13  is fixedly secured. In the upper portion of scoop  12  is fixed protrusion  11 . The upper portion of opposite scoop blade  13  has a slot  10  that slides forward and backward on the fixed protrusion  11 . In one embodiment, protrusion  11  may be a bolt. The top or head of the protrusion may be wider then slot  10  to ensure the protrusion will be confined within the slot  10 . The efficiency and closing power of the movement of scoop blades  12  and  13  is enhanced by the sliding of scoop  12  into and away from scoop  13 .  
         [0018]    [0018]FIG. 2 shows a cross sectional view of the hinge bracket  9  and the handles  8  of the post hole digger. The handles  8  are securely attached to the hinge bracket by a screw  18  that passes through the hinge bracket  9  and attaches hinge bracket  9  to the handle  8 . In the preferred embodiment, shown in FIG. 7, the screw extends into handle  8  approximately one-half the diameter of handle  8 . It is recognized that other attachment methods are possible such as a nut and bolt combination, adhesive or rivets. The hinge bracket  9  has a rotatable attachment  17  joining the two halves of the hinge bracket  9  between the handles  8 . The rotatable attachment  17  rotates to translate the motion applied to the handles to the opening and closing of the scoops for the removal of dirt from the hole. This allows for the digging of a hole of essentially uniform diameter in which the width or diameter of the hole is only slightly larger than the distance between scoop blades  12  and  13  in the open position without appreciably enlarging the upper portion of the hole. The hinge bracket  9  is preferably made of hardened steel and the handles  8  of wood. It is recognized that other durable materials can be used to fabricate hinge bracket  9 , such as aluminum, plastics, and other suitable materials known in the art. Suitable metals, fiberglass, plastic and plastic coated materials can be used to fabricate handles  8 .  
         [0019]    [0019]FIG. 3A shows an enlarged side view of the scoops. In FIG. 3A, arrow  15  depicts the direction in which scoop blade  13  slides on protrusion  11  which projects through slot  10 . Scoop blades  12  and  13  are able to slide into or away from each other. The scoops of the post hole digger can be made of any material that is suitable for outdoor use and digging. Preferably the material will be durable, generally non-corroding and substantially lightweight. Some of the materials that may be used include, but are not limited to aluminum, hardened steel and others. In a preferred embodiment, the scoop blades will be made of hardened steel. The material composing the scoop blades can be varied accordingly to the type of soil being dug such as a loose sandy soil or a hard-packed clay soil. The scoops can be attached to the handle by pressure insertion or by a bolt or a screw or by other methods well known in the art.  
         [0020]    [0020]FIG. 3B depicts the scoops in an alternative embodiment in which both scoops are identical. One side of the upper portion scoop blade  6   a  defines a hole  16  through which protrusion  11  passes. (See FIG. 3A). The opposite side of the upper portion of scoop blade  6   a  defines a slot  10  that will allow for the sliding movement. Once the hole  16  and the slot  10  from each pair of scoop blades  6   a  are aligned, the protrusion  11  is passed through both holes  16  and is secured. In one embodiment, protrusion  11  is a bolt. In a variation, protrusion  11  may be two bolts used to connect the pair of scoops  6   a  together. In either variation, the top or head of the protrusion is wider than the width of the slot  10  allowing for stable sliding movement and stronger closing power. The head of the protrusion  11  is defined as part or all of that portion of the protrusion that extends through slot  10 . FIG. 3B also depicts a receiving section  32  formed to receive handle  8 . Persons of ordinary skill in the art will recognize that other methods exist to movably attach scoops  6   a  to handles  8  such as rods with internal or external threading to receive bolts, nuts or rivets and threaded receiving section  32  adapted to receive a handle with a compatibly threaded end.  
         [0021]    [0021]FIGS. 4A and 4B show side views of alternative embodiments of the post hole digger where each scoop is contiguous with a hinge bracket section, together forming one piece. In FIG. 4A an alternative embodiment of the post hole digger  14  has each scoop  30  and  32  contiguous with a hinge bracket section  37  and  38 , respectively, each forming one piece with scoop blade  30  and  32  respectively. It should be recognized that the handle/scoop component can be fabricated into a single unitary part with each unitary part joined to form post hole digger  14 . As in FIG. 1A, the device has a pair of handles  8 , two digging scoops  30  and  32  and a hinge bracket formed by sections  37  and  38 . In this view the sections  37  and  38  of the hinge bracket keep the scoops section  30  and  32  in an angle. It should be appreciated that hinge sections  37  and  38  may be attached in an approximately straight line perpendicularly transversing the handles  8  at the top of the hinge similar to the embodiment of FIG. 1B. The trimming at the sides of the hinge bracket allows for more power or force to be applied to the scoops. The scoop  30  is elongated in the upper section to join a section from the hinge bracket section  37  to form one contiguous piece. Similarly, hinge section  38  is joined with scoop  32  to form one contiguous piece. In a preferred embodiment, hinge bolt  7  is located 20-21 inches from the scoop tip  40 . In a more preferred embodiment hinge bolt  7  is 10-18 inches from the scoop tip  40 . In a most preferred embodiment, hinge bolt  7  is 12-14 inches from the scoop tip  40 . However, any suitable distance between the hinge bolt  7  and scoop tip  40  will allow the hinge bracket to translate the movement of handles  8  to the scoop blades  30  and  32  enabling the scoops to close. It should be understood that the hole digger is still functional if the bracket is located at the midpoint as in FIG. 1A or as low as approximately 16 inches above the scoop tip. At the end of each handle  8 , a scoop blade  30  or  32  is fixedly secured with a screw  39 . It can be appreciated that other means available to someone of ordinary skill in the art could be used to secure the handle to the scoop blade, such as adhesive, bolts, threaded connections or pressure fitting. In the upper portion of scoop  32  is a fixed bolt  11  as in FIG. 1B. The upper portion of opposite scoop blade  30  has a slot  10  that slides forward and backward on the fixed bolt  11  as in FIG. 1B. The efficiency and closing power of the movement of scoop blades  30  and  32  is enhanced by the sliding of scoop  30  into and away from the fixed scoop  32 . It should be understood that the hole digger also functions if the scoops are joined by a bolt  29  as in FIG. 1A or are not joined except by the hinge bracket sections.  
         [0022]    [0022]FIG. 4B illustrates a most preferred embodiment of the post hole digger  14  where each scoop  42  and  43  is contiguous with a hinge bracket section  40  or  41 , forming one piece. The post hole digger  14  shown in FIG. 4B is similar to the post hole digger  14  shown in FIG. 4A except for the cutout region  44  present in  4 A and the angled handles  8  shown in FIG. 4B. The contiguous region from scoop  42  to hinge section  40  forms a solid panel  45  that defines slot  10 . The arrangement of scoop  43  and hinge section  41  are the same as that of scoop  42  and hinge section  40 . The solid panel  45  adds strength and leverage to the design. In the most preferred embodiment depicted in FIG. 4B, solid panel  45  measures approximately 4 inches from hinge bolt  7  to sliding bolt  11 . However, persons skilled in the art will understand that the use of shorter and longer solid panels will allow the attached hinge bracket sections  40  and  41  to translate the movement of the handles scoops  42  and  43  enabling the scoops to close. It also should be understood that the hole digger is still functional if the bracket is located as in FIB.  1 A or as in FIG. 4A. In this most preferred embodiment, the handles  8  cross in front of each other when the scoops of the digger are in the open position. FIG. 4C illustrates a front view of this most preferred alternate embodiment. It can be appreciated in FIG. 4C that the handles, when in the crossed position, allow for a space to be present at the top of the handles. The operator of the hole digger moves the handles away from each other to close the scoops and remove the dirt from the hole.  
         [0023]    [0023]FIG. 5 shows an enlarged front view of an alternative embodiment of scoop blade  35 . The figure depicts the ground braking edge or blade of the scoop with teeth  33 . The teeth  33  at the tip have a slight bend towards the opposite scoop. The bend of the teeth has an angle  34  in the range of 0° to 28° degrees. In the most preferred embodiment, the bend angle  34  is between 18° to 22° degrees. The teeth  33  with the slight angle  34  at the edge contribute to closing of the scoops with less force, making removal of dirt from the hole less tiring when digging in certain soils. The teeth  33  can be present or absent from the digging blades in any of the embodiments presented in this application.  
         [0024]    [0024]FIGS. 6A and 6B depict the one embodiment of post hole digger of the instant invention and a prior art post hole digger, respectively, in operation. In FIG. 6A, it can be appreciated that the hole  19  dug by the post hole digger  14  of the present invention is relatively uniform in diameter from top to bottom. In comparison, the hole dug by the prior art post hole digger  27  is wider at the ground surface than at the bottom. The prior art post hole digger  27  has two scoop blades  26  and  24  and a bolt  25  joining both scoop blades. Both of the scoops are fixed in position by the bolt  25  whereas in the present invention post hole digger  14  has a fixed scoop  43  and a sliding moving scoop  42 . It can be appreciated that each of the scoops is contiguous with a hinge bracket section  40  or  41 , forming one piece. The hinge bracket limits the movement of the handles  8 . The hinge bracket has a pin  7  that rotates to translate the minimum motion applied to the handles  8  into movement of the scoops  42  and  43  allowing the opening and closing of the scoops  42  and  43 . In this figure the scoops  42  and  43  are closed, showing the uncrossing of the handles  8 . Line  21  illustrates the width of the open handles. In contrast, with the prior art post hole digger  27 , as the hole  20  becomes deeper, the movement of the handles  23  becomes wider and more extreme creating a tapered hole rather the more uniform hole  19  fashioned by post hole digger  14  of the instant invention. The teeth  33  can also be observed in the close position of the scoops, allowing for a better grasp of dirt with a minimum of force in some soils. Persons skilled in the art will realize that in all embodiments described herein, longer handles and suitably placed hinge brackets or hinge sections will enable the digging of deeper holes with approximately uniform diameter.