Abstract:
A method and apparatus employing an axially elongated ground piercing tool for forming an in-ground tunnel under a surface structure with forward axial movement of the tool in the ground under the structure with a pipe carried by the tool for depositing in the tunnel after a removal of a tip of the tool and a rearward pulling of the remainder of the tool from the tunnel.

Description:
RELATED APPLICATION  
       [0001]     This application is a division of U.S. application Ser. No. 10/798,647, filed Mar. 11, 2004 by the same sole inventor-applicant claiming the same small entity status, copies of the original declaration and claim for small entity status filed Mar. 11, 2004 being submitted with this application. 
     
    
     FIELD OF INVENTION  
       [0002]     The present invention relates to a method and apparatus for installing underground pipe and, more particularly, to a method, system and system components for installing underground pipe under existing surface structures.  
       BACKGROUND OF INVENTION  
       [0003]     The inventor of the method, system and system components for installing underground pipe under existing surface structures described herein, also is the inventor of the earth piercing tool covered by U.S. Pat. No. 5,950,739 issued Sep. 14, 1999, the subject matter of which is incorporated herein as background to the present invention.  
         [0004]     The present invention incorporates an improved version of the patented earth piercing tool which is particularly useful in a method and system for installing underground pipe under existing surface structures such as driveways, curbs, sidewalks, concrete slabs, building foundations and the like.  
       SUMMARY OF INVENTION  
       [0005]     The present invention comprises a method and system that are particularly useful in installing underground pipe under pre-existing surface structures. Basically, the method and system employs an axially elongated ground-piercing tool for forming an in-ground tunnel under a surface structure with forward axial movement of the tool in the ground under the structure. The tool includes a removable pointed tip portion threaded to a threaded forward end portion of an axially extending rod portion of the tool. A pipe is carried by the rod and is secured between the tip and an end cap for the rod. After the tunnel is formed, the pipe is placed in the tunnel by removal of the tip from the rod and by a rearward pulling of the rod from the tunnel leaving the pipe in place. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0006]      FIG. 1  is an exploded side view, partially in section, of a preferred form of the ground tunneling tool included in the system of the present invention.  
         [0007]      FIG. 2  is an enlarged side view, partially in section, of a forward end portion of the tool shown in  FIG. 1 , comprising a pointed tip portion threaded to a threaded forward end portion of an axially extending rod of the tool.  
         [0008]      FIG. 2A  is an enlarged side view, partially in section, of an alternate forward end portion of the tool similar to that shown in  FIG. 2 , comprising a pointed tip portion threaded to a threaded forward end portion of an axially extending rod of the tool.  
         [0009]      FIG. 3  is an enlarged side view, partially in section, of a rearward end portion of the tool shown in  FIG. 1 , comprising a rear threaded end portion of the rod of the tool and a threaded end cap for the tool  
         [0010]      FIG. 3A  is an enlarged side view, partially in section, of an alternate rearward end portion of the tool similar to that shown in  FIG. 3 , comprising a rear threaded end portion of the rod of the tool and a threaded end cap for the tool.  
         [0011]      FIGS. 4-7  diagrammatically depict the method of installing underground pipe under an existing surface structure with the system and components of the present invention.  FIG. 4  depicts a side view of a section of ground having a surface structure thereon and the ground piercing tool in an open trench to a right side of the structure.  FIG. 5  depicts the tool of  FIG. 4  having been driven under the structure with a pointed tip end of the tool extending into an open trench on a left side of the structure, the tool having a rod extension connected to the rod shown in  FIG. 4 .  FIG. 6  depicts the side view of  FIG. 5  after the pointed tip of the tool has been removed and replaced by a pipe connector connected to a length of pipe.  FIG. 7  depicts the structure of  FIG. 6  after the tool has been pulled to the right to pull the pipe into the in-ground tunnel formed by the tool and after the tool and pipe connector have been removed from the pipe.  
         [0012]      FIG. 8  is an enlarged exploded side view of an externally threaded forward end portion of the rod and a pipe connector having an internally threaded rear end portion for mating with the rod and an internally threaded forward end for mating with a threaded end of a pipe.  
         [0013]      FIG. 8A  is an enlarged exploded side view of an internally threaded forward end portion of the rod and a pipe connector having an externally threaded rear end portion for mating with the rod and an internally threaded forward end for mating with a threaded end of a pipe.  
         [0014]      FIG. 9  is an enlarged exploded side view of an externally threaded forward threaded end portion of the rod and a pipe connector having an internally threaded rear end portion for mating with the rod and a forward end carrying self tapping threads for forming internal threads and mating with an end of a plastic pipe.  
         [0015]      FIG. 9A  is an enlarged exploded side view of an internally threaded forward end portion of the rod and a pipe connector having an externally threaded rear end portion for mating with the rod and a forward end carrying self tapping threads for forming internal threads and mating with an end of a plastic pipe.  
         [0016]      FIG. 10  is a view similar to  FIG. 1  with a pipe on the rod of the ground piercing tool.  
         [0017]      FIGS. 11   a - c  illustrate the method of driving the tool and pipe combination under a sidewalk and then removing the tool leaving the pipe in place. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0018]     In the drawings,  FIGS. 4-7  depict a sequence of steps comprising a method for installing a pipe  10  under a pre-existing surface structure  12 . By way of example only, the illustrated structure  12  comprises a concrete sidewalk  14  on a preformed horizontally extending bed  16  slightly below a ground surface  18   
         [0019]     An object of the method of the present invention as depicted in  FIGS. 4-7  is to place the pipe  10  in the ground under the sidewalk  14 . A first step in the illustrated method is to form in-ground trenches  20  and  22  on the right and left sides of the sidewalk  14 . This may be accomplished by hand digging of the trenches or formation of the trenches with a backhoe or other mechanical device. The purpose of the trenches  20  and  22  is to expose ground on opposite side of the sidewalk  14  to a ground piercing system  24  according to the present invention.  
         [0020]     A major component of the system  24  is an axially elongated earth piercing tool  26 , such as shown in  FIG. 1 . As will be hereafter described in greater detail, the illustrated tool  26  comprises a pointed tip  28  releasably connected to a forward end of a rod  30  and an end cap  32  releasably connected to a rear end of the rod.  
         [0021]     As illustrated in  FIG. 4 , the tool  26  is placed in the trench  20  with the tip  28  facing toward the trench  22 . Then, as indicated by the arrow  34 , the tool  26  is driven to the left through the ground under the sidewalk  14  as by striking the end cap  32  of tool with a sledgehammer or other suitable rod-driving tool or mechanism. In moving through the ground, the tool  26  forms an in-ground tunnel  36 , under the sidewalk  14 .  
         [0022]     As depicted in  FIGS. 4 and 5 , the tool  26  is shorter in length than the width of the sidewalk  14 . Therefore, in order to form the tunnel  36  completely under the sidewalk  14 , a second or extension rod  30   a  is added to the tool  26  during the formation of the tunnel  36 . For example, after the tool  26  is driven forward under the sidewalk  14  and the pointed tip  28  reaches a mid-point under the sidewalk, the end cap  32  is removed from the rod  30  and the extension rod  30   a  is releaslably connected to the rod  30 . The end cap  32  is then connected to a rear end of the extension rod  30   a  and the driving of the tool  26  continued until the tip  28  extends into the trench  22  as depicted in  FIG. 5 .  
         [0023]     The pointed tip  28  is then removed from the forward end of the rod and replaced by a pipe connector  38 . The pipe connector  38  may be pre-connected to an end of the pipe  10  or may be connected to the pipe after connection to the rod  30 .  FIG. 6  depicts the pipe connector  38  with the pipe  10  releasably connected to a forward end thereof and the rod  30  releasably connected to a rear end thereof.  
         [0024]     As represented by the arrow  40  in  FIG. 6 , with the pipe  10 , pipe connector  38  and tool  26  connected as shown in  FIG. 6 , a rearward pulling force is exerted on the tool  26  to pull the pipe  10  into and through the in-ground tunnel  36  under the sidewalk  14 . The pipe connector  38  is then removed from the pipe  10  leaving the pipe in the tunnel  36  as depicted in  FIG. 7 .  
         [0025]     Referring now more specifically to the earth piercing system  24  for performing the method illustrated in  FIGS. 4-7 ,  FIG. 1  illustrates the system  24  as comprising the rod  30  having a forward threaded end portion  42  and a rear threaded end portion  44 . The forward end portion  42  is designed to releasably connect to a rear threaded end portion  46  of the pointed tip  28  while the rear end portion  44  is designed to releasably connect to a forward threaded end portion  48  of the end cap or to a forward threaded end of an extension rod such as  30   a  in  FIG. 5 . As described with respect to the method illustrated in  FIGS. 4-7 , the forward end portion  42  of the rod  30  also is designed to releasably connect to a rear threaded end portion  50  of the pipe connector  38 .  
         [0026]     A first preferred design for the forward threaded end portion  42  of the rod  30  and rear threaded end portion  46  of the tip  28  is depicted in  FIG. 2 . As shown, the end portion  42  comprises an axially extending externally threaded extension  62 . As depicted, the extension  62  has a reduced diameter relative to an adjacent forward end  64  of the rod  30  so as to define an annular forward facing radial shoulder  66  outward of the extension. External threads  62   a  on the extension  62  are designed to screw into and mate with internal threads  46   a  in a rear axially extending socket  68  in the tip  28  defining the rear threaded end portion  46  of the tip. Further as shown in  FIG. 2 , a rear facing radially extending annular end  70  of the tip  28  outside of the socket  68  defines an end surface  72  engaging the shoulder  66  when the extension  62  is fully threaded into the socket. Thus connected, axial impact forces exerted on the rod  30  as it is driven under the sidewalk  14  are transmitted by the shoulder  66  and end  72  connection to the forward end of the tip  28  to relieve axial forces on the mating threads of the extension  62  and socket  68 .  
         [0027]     A similar connection exists between the end cap  32  and rod  30  or extension  30   a  as depicted in  FIG. 3 . With regard to the extension  30   a,  it may be connected to the rod  30  in the same manner that the rod  30  is connected to the tip  28  as described relative to  FIG. 2  or it may be connected in the manner that the rod  30  is connected to the tip  28  as will be described relative to  FIG. 2A . In either event, as shown in  FIG. 3 , the end cap  32  comprises an axially extending externally threaded extension  74 . As depicted, the extension  74  has a reduced diameter relative to an adjacent forward end  76  of the cap  32  so as to define an annular forward facing radial shoulder  78  outward of the extension. External threads  74   a  on the extension  74  are designed to screw into and mate with internal threads  44   a  in a rear axially extending socket  80  in the rod  30  or extension  30   a  defining the rear threaded end portion  44  of the rod. Further as shown in  FIG. 3 , a rear facing radially extending annular end  82  of the rod  30  or extension  30   a  outside of the socket  80  defines an end surface  79  engaging the shoulder  78  when the extension  74  is fully threaded into the socket. Thus connected, axial impact forces exerted on the cap  32  as it is driven forward are transmitted by the shoulder  78  and end surface  79  connection to the forward end of the tip  28  to relieve axial forces on the mating threads of the extension  74  and socket  80 .  
         [0028]     A second preferred design for the forward threaded end portion  42  of the rod  30  and rearward threaded end portion  46  of the tip  28  is depicted in  FIG. 2A . As shown, the end portion  46  of the tip  28  comprises an axially extending externally threaded rear extension  62 ′. As depicted, the rear extension  62 ′ has a reduced diameter relative to an adjacent forward end  64 ′ of the tip  28  so as to define an annular rear facing radial shoulder  66 ′ outward of the extension. External threads  62   a′  on the extension  62 ′ are designed to screw into and mate with internal threads  46   a′  in a forward axially extending socket  68 ′ in the rod  30  defining the forward threaded end portion  42  of the rod. Further as shown in  FIG. 2A , a forward facing radially extending annular end  70 ′ of the rod  30  outside of the socket  68 ′ defines an end surface  72 ′ engaging the shoulder  66 ′ when the extension  62 ′ is fully threaded into the socket. Thus connected, axial impact forces exerted on the rod  30  as it is driven under the sidewalk  14  are transmitted by the shoulder  66 ′ and end surface  72 ′ connection to the forward end of the tip  28  to relieve axial forces on the mating threads of the extension  62 ′ and socket  68 ′.  
         [0029]     A similar connection exists between the end cap  32  and rod  30  or extension  30   a  as depicted in  FIG. 3A . As shown in  FIG. 3A , the rod  30  or extension  30   a  comprises an axially extending externally threaded extension  74 ′. As depicted, the extension  74 ′ has a reduced diameter relative to an adjacent rear end  76 ′ of the rod  30  or extension  30   a  so as to define an annular rear facing radial shoulder  78 ′ outward of the extension. External threads  74   a′  on the extension  74 ′ are designed to screw into and mate with internal threads  44   a′  in a forward axially extending socket  80 ′ in the end cap  32  defining the rear threaded end portion  44  of the rod or extension. Further as shown in  FIG. 3A , a forward facing radially extending annular end  82 ′ of the end cap  32  outside of the socket  80 ′ defines an end surface  79 ′ engaging the shoulder  78 ′ when the extension  74 ′ is fully threaded into the socket. Thus connected, axial impact forces exerted on the cap  32  as it is driven forward are transmitted by the shoulder  78 ′ and end surface  79 ′ connection to the forward end of the tip  28  to relieve axial forces on the mating threads of the extension  74 ′ and socket  80 ′.  
         [0030]     As previously described with respect to the method of  FIGS. 4-7 , the system  24  also comprises the pipe connector  38 . Specifically,  FIG. 6  shows the pipe connector  38  connected to the rod  30  and to the pipe  10 . Preferably, such connections are provided by the rear threaded end portion  50  of the connector releasably engaging the forward threaded end portion  42  of the rod  30  and a forward threaded end portion  52  of the pipe connector  38  engaging a threaded outer rear end  56  of the pipe (see  FIG. 8 ) or a rear interior thread  58  formed in a rear interior  60  of the pipe by a forward threaded end portion  52 ′ of the pipe connector (see  FIG. 9 ).  
         [0031]     A first preferred design for the forward threaded end portion  42  of the rod  30  and the rear threaded end portion  50  of a metal-to-metal version of the pipe connector  38  for a metal pipe is depicted in  FIG. 8 . As previously described relative to  FIG. 2 , the end portion  42  comprises the axially extending externally threaded extension  62 . As depicted, the extension  62  has a reduced diameter relative to an adjacent forward end  64  of the rod  30  so as to define the annular forward facing radial shoulder  66  outward of the extension. External threads  62   a  on the extension  62  are designed to screw into and mate with internal threads  50   a  in a rear axially extending socket  84  of the pipe connector  38  defining the rear threaded end portion  50  of the connector. Thus, the pipe connector  38  of  FIG. 8  is releasably connectable to the rod  30 .  
         [0032]     Further as shown in  FIG. 8 , the pipe connector  38  comprises a forward facing axially extending socket  86  having internal threads  86   a  designed to screw onto and mate with the external threads  56   a  on the rear end of the pipe  10 .  
         [0033]     With the connector  38  thus connected between the pipe  10  and the rod  30 , rearward axial forces exerted on the rod  30  will be transmitted through the pipe connector  38  to the pipe  10  to pull the pipe through the tunnel  36  under the sidewalk  14  as depicted in  FIG. 6 .  
         [0034]     A similar connection exists between the metal pipe  10  and an alternate forms of the pipe connector  38  and rod  30  as depicted in  FIG. 8A . As there illustrated, the rear threaded end portion of the pipe connector  38  of  FIG. 8A  comprises an axially extending externally threaded rear extension  88 . External threads  50   a′  on the rear extension  88  are designed to screw into and mate with the internal threads  46   a′  in the axially extending forward&#39;socket  68 ′ in the rod  30  depicted in  FIG. 2A . With the rear threaded end of the pipe connector  38  thus connected to the rod  30  and with the forward threaded end portion  52  of the pipe connector  38  connected to the pipe as described relative to  FIG. 8 , rearward axial forces exerted on the rod  30  will be transmitted through the pipe connector  38  to the pipe  10  to pull the pipe through the tunnel  36  under the sidewalk  14  as depicted in  FIG. 6 .  
         [0035]     A first preferred design for the forward threaded end portion  42  of the rod  30  and the rearward end portion  50  of a metal-to-plastic pipe connector  38  for a plastic pipe is depicted in  FIG. 9 . As previously described relative to  FIG. 2 , the end portion  42  comprises the axially extending externally threaded extension  62 . As depicted, the extension  62  has a reduced diameter relative to an adjacent forward end  64  of the rod  30  so as to define the annular forward facing radial shoulder  66  outward of the extension. External threads  62   a  on the extension  62  are designed to screw into and mate with internal threads  50   a  in a rear axially extending socket  84 ′ of the pipe connector  38  defining the rear threaded end portion  50  of the connector. Thus, the pipe connector  38  of  FIG. 9  is releasably connectable to the rod  30 .  
         [0036]     Further, in  FIG. 9 , the pipe connector  38  is illustrated as comprising an axial forward extension  90  defining the forward threaded portion  52 ′ of the connector. As depicted, the extension  90  is radially stepped including a front portion  54  of relative small diameter and a rear portion  54   a  of relative large diameter. The portions  54  and  54   a  carry conventional thread cutting teeth  92  for cutting threads in the interior of the open end of a plastic pipe. For example, the diameter of the teeth  92  carried by the portion  54   a  of the extension  92  are designed to cut threads such as  58  in the plastic pipe  10  upon a turning of the pipe connector  38  relative to the pipe  10  with the portion  54   a  of the extension  90  within the pipe. The teeth  92  carried by the portion  54  are for cutting similar threads in a narrower plastic pipe (not shown).  
         [0037]     Once the teeth  92  on the portion  54   a  of the pipe connector have formed the thread  58 , the pipe is secured to the pipe connector. Then, with the rod  30  secured to the pipe connector  38  in the manner previously described, rearward axial forces exerted on the rod will be transmitted through the pipe connector to the pipe  10  to pull the pipe through the tunnel  36  under the sidewalk  14  as depicted in  FIG. 6 .  
         [0038]     A similar connection exists between the plastic pipe  10  and an alternate form of the pipe connector  38  and rod  30  as depicted in  FIG. 9A . As there illustrated, the forward end portion  52  of the pipe connector  38  conforms that that shown and described relative to  FIG. 9 . However, the rear threaded end portion of the pipe connector  38  of  FIG. 9A  comprises an axially extending externally threaded rear extension  88 ′ like the extension  88  in  FIG. 8A . As in  FIG. 8A , external threads  50   a′  on the rear extension  88 ′ are designed to screw into and mate with the internal threads  46   a′  in the axially extending forward socket  68 ′ in the rod  30  as depicted in  FIGS. 2A and 8A .  
         [0039]     With the rear threaded end of the pipe connector  38  thus connected to the rod  30  and with the forward threaded end portion  52  of the pipe connector  38  connected to the pipe as described relative to  FIG. 8 , rearward axial forces exerted on the rod  30  will be transmitted through the pipe connector  38  to the pipe  10  to pull the pipe through the tunnel  36  under the sidewalk  14  as depicted in  FIG. 6 .  
         [0040]     While in the foregoing, preferred embodiments of the present invention and preferred modes of operation thereof have been described and illustrated in detail, changes and modifications may be made without departing from the spirit of the present invention. For example, when installing relatively short lengths of pipe under relatively narrow structures, such as narrow sidewalks, the forward end portion  42  of the rod  30  of the ground piercing tool  26  can be dimensioned to fit within such a pipe  100  as depicted in  FIG. 10 . Under such circumstances, after the tip  28  of the tool  26  has been removed from the rod  30 , the forward end of the rod may be inserted into the pipe  100  and the tip  28  reconnected to the rod. Then, as shown in  FIG. 10 , the pipe  100  is fully mounted on and carried by the rod  30  between the end surface  72  of the tip and the outwardly enlarged end portion  102  of the rod connected to the end cap  36 . Thus positioned, the pipe  100  may be driven with the tool  26  under a sidewalk  104  as depicted in  FIGS. 11   a - c.  As illustrated, such a tool/pipe combination may be placed in a preformed trench  106  on one side of the sidewalk  104 . The tool  26  may be driven under the sidewalk  104  in the manner previously described until the tip  28  extends into a preformed trench  108  on an opposite side of the sidewalk  104 . Then, the tip  28  may be removed from the rod  30  and the rod pulled rearward into the trench  106  leaving the pipe  100  in place under the sidewalk.  
         [0041]     Accordingly the present invention is to be limited in scope only by the following claims.