Abstract:
A method and device for installing a tube of a geothermal closed loop system in the ground. A drill rod includes a hook for removably mounting the heat exchange tube for positioning the tube in the hole bored in the ground by the drill bit. The tube may be inserted into the bored hole once the drill is removed therefrom, mounted to the tube and then reinserted into the hole. Alternatively, the tube is mounted to the drill rod as the hole is being bored.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to the field of devices and methods for installing geothermal closed loops in the ground. 
         [0003]    2. Description of the Prior Art 
         [0004]    Geothermal heating and cooling systems operate by exchanging heat between the constant temperature ground and a heat exchange medium circulated in a tube extending through the ground. In order to cool a building, heat within the building flows into the coolant medium within the tube extending from the building and through ground. The reverse is true when heating a building wherein heat from the ground flows into the coolant medium which is then circulated via the tube in the building with the heat flowing from the coolant tube into the building. 
         [0005]    In an open loop system, existing ground water is used as the heat exchange medium which flows through the tube. The water may be obtained from a well, pond or lake or water located beneath ground. 
         [0006]    In a closed loop system, the tube or pipe holding the heat exchange medium may be arranged in horizontal loops placed four to six feet below ground and installed using a backhoe along the length of each loop. A considerable amount of land is required to accommodate a horizontal system. Conventional boring machines allow the bored hole to extend downward into the ground and then upwardly exiting the ground at a distance located a great distance from the entrance to the hole. Once the drill head exits the hole, the heat exchange tube is mounted to the drill head and pulled back through the hole. To create a hole that extends downward and then horizontally and then upwardly requires a great horizontal distance due to the limitations of the boring machine. Alternatively, the tubes carrying the heat exchange medium may extend vertically for hundreds of feet below ground and installed by a well digging rig. 
         [0007]    In the case of utilizing the above described open loop systems or closed loop systems, well digging machines, backhoes, and boring devices are brought onto the land for boring of the holes resulting in considerable damage to the turf and landscape. In many cases, the size of the lot may not allow sufficient room for the use of all of the equipment to create the holes. Further, the holes may extend horizontally such a great distance so as to extend beyond the boundary of the lot. On residential property landscaped prior to installation of a geothermal system, the resultant expense and mess caused by the hole boring machine presents a significant drawback to the installation of the geothermal system. 
         [0008]    Disclosed herein is a device and method for installing a u-shaped tube into a single hole thereby minimizing the destruction to the landscape while also providing for a quicker installation minimizing the construction cost. Further, a small pit roughly five feet in width, length, and depth is created with the hole being bored at the bottom of the pit allowing the water, dirt, etc. to move upwardly from the bored hole into the pit. Once the u-shaped coolant tube is installed, the material may then flow from the pit into the hole thereby surrounding the tube and improving the heat transfer between the tube and the ground. A particular advantage results since the pit limits the amount of damage to the landscaped ground by containing the material from the boring process. 
       SUMMARY OF THE INVENTION 
       [0009]    One embodiment of the present invention is a method of installing a tube of a geothermal closed loop system in the ground by using a rotatable drill rod with a drill bit for drilling a hole in the ground. The steps include creating a pit in the ground to receive water and dirt removed from drilling a blind hole in the ground. A drill rod is used to install a tube in the blind hole with the tube having an inlet portion and an outlet portion both extending out of the entrance of the blind hole. 
         [0010]    A further embodiment of the present invention is a device for creating a geothermal closed loop using a U-shaped tube positioned in a blind hole in the ground. The tube has an inlet tubular portion and an outlet tubular portion extending out of the blind hole. The device includes a drill rod with a drill bit mounted to the drill rod; and, a mount on the drill end portion for mounting and holding the U-shaped tube but releasing the U-shaped tube as the drill end portion is pulled from the blind hole leaving the tube within the ground. 
         [0011]    It is an object of the present invention to provide a new and improved method for installing a tube of a geothermal closed loop system into the ground. 
         [0012]    A further object of the present invention is to provide a device for use in installing a u-shaped tube in the ground for use with a geothermal system. 
         [0013]    Related objects and advantages of the present invention will be apparent from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a top view of the geothermal system installed on a lot. 
           [0015]      FIG. 2  is a side elevation view of geothermal line  26  located beneath the ground level. 
           [0016]      FIG. 3  is a fragmentary perspective view of a conventional drill used in drilling a geothermal hole for use in practicing the preferred embodiment of the present invention. 
           [0017]      FIG. 4  is a fragmentary perspective view with the u-shaped tube attached to the drill end portion having a cone shaped closed end used in practicing the preferred embodiment. 
           [0018]      FIG. 5  is a fragmentary side view of the drill rod connected by a bearing to the heat exchange tube and an evacuation tube used to practice the method disclosed herein all according to the alternate embodiment of the present invention. 
           [0019]      FIG. 6  is an enlarged cross-sectional view taken along the line  6 - 6  of  FIG. 5  and viewed in the direction of the arrows. 
           [0020]      FIG. 7  is an enlarged end view of the boring head shown in  FIG. 5 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0022]    Referring to  FIG. 1 , there is shown a schematic top diagram of a geothermal system connected to a building. The building or house  20  is constructed on lot  21  having side boundaries on  22  and  23  along with end boundaries  24  and  25 . A driveway extends from the building to the street or road. Six separate geothermal lines  26 - 31  extend beneath ground level and fan out from a pit  32 . Each geothermal line  26 - 31  is formed by digging a blind hole into the ground with a separate geothermal tube positioned within each hole forming the geothermal lines  26 - 31 . The tubes within the holes are then connected together funneling into an outlet tube  34  and an inlet tube  35  leading to a conventional heat exchanger  36  located within or adjacent building  20 . 
         [0023]    Pit  32  is formed by rolling back a 4×6 foot area of sod using conventional tools, such as, a backfill blade on an excavator. Pit  32  is then dug to a depth of five feet and provides a starting point for the six holes leading to the six geothermal lines  26 - 31 . As each hole is dug, pit  32  provides a storage area for the removed dirt and water in a confined area and also allows material to drain back into each bored hole as needed to pack around u-shaped tubes inserted into the six bored holes. 
         [0024]    While the drawings show a total of six geothermal lines, it is to be understood that the present invention includes less than or more than six lines depending upon the amount of heat exchange required for building  20 . Typically, each line must be approximately  150  feet in length to provide one ton of air conditioning. In order to minimize the horizontal space occupied by the lines, the bored holes are drilled downward at an angle relative to horizontal. For example, in  FIG. 2 , line  26  includes a bored hole  36  at an approximate angle  17  of 19 degrees relative to a horizontal line  18 . By extending the bored holes down at an acute angle relative to the horizontal, the length of the hole may be optimized given the limitation of the horizontal distance between the boundary lines  24  and  25  of the lot upon which the facility is located. 
         [0025]    In many cases, rock formations are located beneath ground level  33 . For example, in the event a rock formation or rock layer exists  100  feet below ground level, then if the bored holes are drilled only in a vertical direction, difficulty is incurred for drilling of a  150  foot hole as the drill bit drills through the rock. Thus, by orienting the bored hole at an acute angle relative to horizontal, difficulties may be avoided from a rock formation while also maximizing the length of the hole relative to the boundaries of the lot. In the event the bored holes extend beyond the lot boundary line, then covenants may limit the sizing of the length of the hole. The method of the present invention therefore includes the step of orienting the drill rod with attached drill bit at an acute angle relative to horizontal as the hole is drilled in the ground. In order to determine angle  17 , the desired length of the bored hole must first be selected with the acute angle then being calculated given the desired length and either the horizontal distance, permissible by the lot boundaries, of the desired bored hole or the vertical distance, permissible by the depth of rock formations, beneath ground to which the hole is to extend. 
         [0026]    Since pit  32  is only four to six feet across and five feet deep, it is necessary to start boring the hole at a distance from the pit in order to orient the hole at a 19 degree angle relative to horizontal. Thus, the drill bit is rotated into the ground at location  86  ( FIG. 2 ) apart from the hole creating a 19 degree hole  85  which enters the pit side wall  87  at location  88 . The drill bit continues to rotate and moves into the pit engaging the bottom wall of the pit creating entrance  55  of hole  36  also oriented at a 19 degree angle relative to the horizontal. It is desirable that hole  55  be created in the bottom wall of the pit in order to allow the material from the hole to exit the hole into the pit and eventually move back into the hole once the heat exchange tube is located in the hole. 
         [0027]    Referring to  FIG. 3 , drill rod  42  has one end  41  attached to a conventional hole boring machine  39  such as available from Vermeer Corporation of Pella, Iowa. Machine  39  has a rotatable output releasably connected to end  41  of rod  42  with the opposite end  43  of the rod connected to a conventional drill bit end portion  38 . In the preferred embodiment shown in  FIG. 3 , rod  42  and drill bit end portion  38  are rotated by machine  39  through the bottom of pit  32  ( FIG. 2 ) creating a hole approximately four inches in diameter at a 19 degree angle depending upon the conditions of the ground. Each line is sized for approximately one ton of cooling/heating for the geothermal system installed. The entrance  55  of the hole  36  associated with line  26  is provided at the bottom of pit  32 . Likewise, each hole created for lines  27 - 31  has a separate entrance. 
         [0028]    Once a hole is created, the drill rod  42  and drill bit  38  are removed from the hole. Drill bit  38  is then unthreaded from rod  42  and a drill end portion  37  having a cone shaped closed end  46  ( FIG. 4 ) is mounted to rod  42 . Bit  38  and end portion  37  have an internally threaded socket into which the external threaded male end of rod  42  extends. 
         [0029]    A hooked shaped arm  56  has a proximal end  53  mounted to end portion  37  and forms an open end  52  facing away from rod  42 . Arm  56  is used to pull the u-shaped tube  45  ( FIG. 4 ) into the hole once the hole has been bored and the drill rod  42  with end portion  37  is inserted into the hole. After end  46  reaches the blind end of the hole, the rod  42  with end portion  37  is pulled outward leaving the u-shaped tube  45  within the hole. 
         [0030]    The u-shaped coolant tube  45  is mounted to the arm  56  by any number of fastening means. For example, a cable  47  is extended through the space between tube portion  48  and tube portion  49  of tube  45 . The cable is extended around arm  56  between the space existing between arm  56  and the main body of end portion  37 . A conventional cable clamp  50  then joins the opposite ends of cable  47  securing the u-shaped tube  45  to rod  42  by hooking the tube  45  to arm  56 . So long as rod  42  and end  46  move downward into the bored hole, the arm  56  is operable to pull tube  45  into the hole. Once the drill rod  42  is moved in a direction opposite to arrow  51 , cable  47  moves through open end  52  of arm  56  thereby disengaging cable  47  and tube  45  from the arm leaving in place, within the hole, tube  45  while the drill rod and drill end portion are completely removed from the bored hole. Excellent results have been obtained by using a 3/16 inch braided cable for cable  47 . The width of the cone shaped end  46  must be smaller than the diameter of drill bit end portion  38  so that the bored hole is sufficiently large relative to cone shaped end  46  to prevent interference of end  46  with tube  45  as end  46  is pulled outward from the hole. 
         [0031]    The opposite end portions  48  and  49  ( FIG. 2 ) of tube  45  extend outward through the entrance  55  of the bored hole and are connected to lines  34  and  35 , in turn, connected to heat exchanger  36  ( FIG. 1 ). The opposite end portions  45  and  49  are connected together by joint coupler  54 . Thus, the heat exchange medium is circulated through outlet tube  34  in the direction of arrow  51 , through the tube portion  49  and then back through coupler  54  through tube portion  48  in the direction opposite of arrow  51  to tube  35 , in turn, connected to the heat exchanger. 
         [0032]    In a similar fashion, a hole is bored for line  27  and then line  28  etc. until all of the bored holes are completed as just described with the drill rod and drill bit then being withdrawn sequentially from each bored hole with a separate u-shaped tube connected to arm  56  and inserted into each bored hole thereby forming geothermal lines  26 - 31 . As each u-shaped tube is inserted in the particular bored hole, the water and dirt within the pit is allowed to flow back into the bored hole. Once the inlet tube portion and outlet tube portion of each of the six u-shaped tubes  45  are connected respectively to tubes  34  and  35 , pit  32  may be filled with the sod being replaced. Each of the bored holes forming lines  26 - 31  has a bottom blind end against which each coupler  54  may rest. A universal coupler is used to join the end portions  49  to line  34  and end portions  48  to line  35 . 
         [0033]    An alternate embodiment for installing a geothermal closed loop employs the tool shown in  FIGS. 5 and 6 . The tool allows for the u-shaped tube to be installed into the bored hole at the same time the hole is being created thereby eliminating one of the steps of the previously described method. Further, the drill bit is not removed from the drill rod. Thus, drill rod  42  ( FIG. 5 ) has one end  43  connected to drill end main body  95  whereas the opposite end  41  is connected to boring machine  39 . A bearing  70  has an inner race  71  ( FIG. 6 ) fixedly secured to the drill end main body  95  to prevent relative motion between race  71  and the drill rod and drill end main body. The bearing includes an outer race  72  which freely rotates on race  71 . Bearing  70  employs conventional bearing construction techniques and is commercially available. Fixedly mounted to the outer race  72  of bearing  70  is arm  56  having its proximal end  53  fixedly secured to race  72 . Cable  47  mounts the u-shaped tube  45  to arm  56  in an identical manner as previously described. Thus, with rod  42  and drill end main body  95  rotating, outer race  72  will remain stationary thereby allowing tube  45  to be in a non-rotating condition. 
         [0034]    A ¾ inch hose  76  has a proximal end  77  mounted by a conventional clamp  78  to the outer race  72 . The opposite end  79  of hose  77  extends outward from the entrance  55  of the hole and it is connected to a conventional pump to facilitate extraction of water and dirt from the hole as the hole is being bored and to also allow the pump to force the water and dirt back into the bored hole as the drill rod and drill bit are removed. Each hole is drilled by rotating rod  42  and drill bit main body  95  while at the same time carrying the u-shaped tube  45  into the bored hole being created. End  98  of drill bit main body  95  is fixedly attached to a conventional flat drill bit  94  to rotate therewith. 
         [0035]    The blind holes are formed in a manner identical as previously described. For example, bored hole  36  has an entrance  55  located at the bottom of pit  32  and is angularly positioned relative to the horizontal at angle  17 . The length of the bored hole and the acute angle  17  are calculated as previously described. Drill bit  94  advances into the ground creating the bored hole with the u-shaped tube  45  pulled into the hole behind the drill bit at the same time that the hole is being bored. Once drill bit  94  reaches the desired length of the bored hole creating a blind hole end, the drill bit and drill rod are pulled in a direction opposite of arrow  51  thereby allowing the u-shaped tube to remain in the bored hole since cable  47  disengages arm  56 . 
         [0036]    Drill bit  94  ( FIG. 7 ) has a flat blade boring head operable to bore a hole having a diameter equal to the length  95  of the blade. Thus, the hole is sized to allow for movement of tubes  45  and  76  into the hole as it is bored. When withdrawing the blade from the hole it may be necessary to rotate the blade until the blade is past the tube  45  which remains in the hole. Since hose  76  is fixedly fastened to the outer bearing race  72 , the hose is withdrawn from the bored hole along with the drill rod and drill bit. 
         [0037]    Commercially available monitors are available for locating and for determining the depth and horizontal distance the drill bit extends. Likewise, the angular position of the drill bit about its longitudinal axis may also be determined by such monitors. For example, Digital Controls, Inc., Kent, Wash. distributes a directional drill locating system under the model, name and number Digitrack F2. The Digitrack F2 directional drill locating systems includes a sensor mountable within the drill rod that is operable to transfer back to a remote monitor the roll, pitch, signal strength, temperature and real time as well as indicate the horizontal distance of the drill bit from the monitor and the depth beneath the ground. The drill rod, drill bit and hose are extracted from the bored hole while the slurry water mixture is pumped back into the bored hole ensuring the void in the soil is completely filled. 
         [0038]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.