Abstract:
Disclosed is a coupler that grips the internal surface of a torque receptor such as a pipe or driveshaft to be turned. When torque is applied to the coupler, one or more gripping surfaces are forced apart by a cam mechanism. The gripping surfaces tightly engage the internal surface of the pipe in response to movement of an internal cam. Torque applied to the wrench causes the pipe to turn. Because the wrench grips the internal diameter of a torque receptor, it can be used without damaging the external surface of the torque receptor, and used in very confined spaces. The gripping surfaces distribute the gripping load evenly across the pipe, which minimizes any deformation of the pipe.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in part of U.S. patent application Ser. No. 10/189,968, entitled “Internal Gripping Pipe Wrench,” filed Jul. 3, 2002 now U.S. Pat. No. 6,675,679 by Larry Dugan, which was based upon and claims the benefit of U.S. Provisional Patent Application 60/304,944 entitled “Internal Gripping Pipe Wrench” filed Jul. 12, 2001, the entire contents of which is hereby incorporated by reference for all it discloses and teaches. 

   BACKGROUND OF THE INVENTION 
   a. Field of the Invention 
   The present invention pertains generally to couplers and more particularly to couplers that engage the inner surface of a pipe, driveshaft, or similar device for transmitting torque. 
   b. Description of the Background 
   In the plumbing trade, it is common to attach pipe together using a pipe thread that is tapered, such as the standard National Pipe Thread. These thread systems are designed so that the taper of the threads force the internal and external threads to seal against each other to effect a seal for the joint. The very nature of this coupling system is such that the plumber will apply as much force as possible to ensure a tight seal for the pipes being installed. Often, a compound or putty is applied to the threads at the time of installation, but this compound can harden over time or the pipes may corrode, sometimes making removal of the pipe much more difficult than the installation. 
   The use of tapered threads for joining pipes is a standard method for high-pressure pipes such as steam pipes, gas pipes, and pressurized water, just as examples. The tools required for cutting pipe and cutting threads are part of every plumber&#39;s arsenal of tools, since this type of plumbing is used in almost every home, commercial building, and industrial factory. 
   The plumber will generally install and remove threaded pipe using wrenches that grip the exterior of the pipe when turning. These wrenches fall into two general categories: those with steel or other metal gripping teeth, and those with a compliant webbing. 
   The wrenches with steel teeth, of which the common pipe wrench is an example, are adjusted to apply a gripping force to the pipe while the pipe is being turned. As the turning force is applied, the grip is increased, and the pipe is turned. 
   The wrenches with compliant webbing, such as a strap wrench, consist of a metal handle and a piece of webbing, one end of which is attached to the handle. The free end of the webbing is fed around the pipe to be turned and then through a feature in the handle. As the handle is turned, the handle pinches the strap against the pipe and tightens the strap while simultaneously turning the pipe. A strap wrench described above generally does not have the excellent gripping force of the common pipe wrench with steel teeth. The strap wrench takes a considerable amount of time to install and remove from a pipe before and after turning the pipe, especially when compared to a common pipe wrench. 
   The wrenches with steel teeth that grab the external surface of the pipe to be turned can destroy the external threads especially when short nipples are being turned by the wrench and insufficient unthreaded portions of the nipple are available to grip. Further, external pipe wrenches often leave unsightly and disfiguring teeth marks on the outer surface of the pipe. This is unacceptable for pipe that is, for example, chrome plated and is not hidden from view. An alternative solution to those problems is the use of compression couplings or other types of fittings to join the pipe sections. However, this is more expensive, and a much more time consuming alternative and is often less reliable. 
   Actual deformation of a thin wall pipe is possible when a common pipe wrench is used to remove an old, rusted section of the pipe. This is due to the crushing action of the opposing steel teeth across the diameter of the pipe. The same crushing of the pipe may occur when using a strap wrench, since the handle of the wrench presses directly on the pipe as it pinches the strap against the pipe. 
   Further, all wrenches that engage the external surface of a pipe require some amount of room around the pipe to effectively turn the pipe. For some wrenches, such as the conventional pipe wrench, the amount of room can be considerable, and there are others designed for use in a confined space. However, the wrenches designed for confined space often have severe limitations in terms of ease of use and gripping power, and they always require at least some access to the external portion of the pipe. 
   In addition to the limitation of requiring a considerable amount of room for operation, the common pipe wrench, the strap wrench, and most other devices for turning a pipe are unidirectional in their operation. In other words, the pipe wrench, when being used for turning the pipe, may only turn the pipe in one direction. In order to reverse the direction of turning, the wrench must be removed from the pipe and turned to grip the pipe from the opposite direction, and reinstalled onto the pipe. 
   External pipe wrenches also have limitations for assembly in production factory environments. In such environments speed is paramount. Since the common methods of turning a threaded component with a pipe wrench are slow and cumbersome, much time is wasted using conventional pipe wrenches. Designers of such articles, realizing the slow and cumbersome assembly of threaded pipe oftentimes revert to other more expensive types of couplings. The cost savings realized in using threaded pipe can be substantial since the threading operation can be simply automated in a machining step that only takes a few seconds for both the pipe and the article receiving the pipe. The cost of a separate coupling, including a fastener to engage the coupling, may be much more expensive than the threaded interface. In addition, the threaded interface may provide a more esthetic result. 
   For example, the assembly of articles such as furniture that use components that are cylindrical pipes, such a chrome pipes, may be difficult to assemble using standard pipe wrenches, without marring the exterior cosmetic surface. In addition, high-speed production in factories that assemble boilers, sprinkler systems and components, furnaces, and other systems that use threaded pipe can be substantially limited by the use of a standard pipe wrench. As pointed out above, pipe wrenches are slow and cumbersome, require extra room to maneuver and operate and are generally not effective in a high-speed factory assembly production operation. 
   Various types of internal pipe wrenches solve some of these problems. For example, U.S. Pat. No. 5,207,131 issued to Pool, et al. discloses an oil filter removal tool. The disadvantage of the Pool, et al. device is that it includes springs 44 that bias the jaws of 48, 50 in an outward direction so that the jaws 48, 50 have to be depressed and urged inwardly to be inserted into an oil pan filter cap. U.S. Pat. No. 3,902,384 discloses an internal pipe wrench that has a tapered actuation element that must be adjusted to engage the inner surface of the pipe. Again, this is time consuming and has potentially other numerous disadvantages. Internal pipe wrenches available from BrassCraft have an offset pivot shaft on which a collar is mounted so that the collar becomes offset as the collar rotates around the offset shaft. The offset shaft that causes the collar to become offset and engage the internal portion of the pipe causes the device to be off center so that high speed assembly or disassembly is not achievable using the BrassCraft tools. In addition, the collar constitutes a single piece and does not tend to engage the inner surface of the pipe or nipple well. In addition, the rotatable sleeve must be oriented in a vertically downward position in order to engage a pipe when employed in a horizontal or nearly horizontal position. In that way, gravity can cause the sleeve to rotate in sync to its lowest point to engage the internal surface of the pipe. Since the sleeve has to be at the bottom, this limits the ease of use of the device. Further, in vertical orientations, the BrassCraft device may fail to easily engage the inner surface of the nipple. Further, the sleeve, because of its small size, may deform the pipe and could egg the pipe especially when engaging thin wall pipe. Further, in vertical alignment applications the user&#39;s fingers may have to be used to orient the rotatable sleeve in the correct position in order to insert the brass craft internal pipe wrench. 
   It would therefore be advantageous to provide a coupler that can securely grip a pipe, driveshaft or other shaft (hereinafter collectively referred to as a “torque receptor”) from the inside without marring the outside, support a thin walled torque receptor such as a pipe so that the pipe does not deform while turning even under relatively high forces, be compact and able to work in extremely tight spaces, be simple and quick to use, insert, extract, be universal in direction, and aligned with the center axis of the torque receptor when engaged. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the disadvantages and limitations of the prior art by providing a simple and reliable device for engaging the internal diameter of a pipe, tube, rigid conduit or similar object, a drive coupler, torque transmitter or torque coupler, etc., all of which should be considered to be included in the term “pipe,” “shaft,” or “receptor.” By gripping only the internal surface of the pipe, the external surface is left free from marks and the pipe is supported from any deformation. Further, since the handle or other mechanism for turning the wrench can be configured in many different ways, and almost the entire gripping mechanism is located inside the pipe, the space around the pipe that is required to turn the pipe is minimal. The present invention may also be universal in direction (i.e., can be operated in either turning direction without making any adjustments) so that the user does not have to think about the proper orientation prior to use. 
   The present invention may therefore comprise a coupler that is adapted to engage a cylindrical concave internal surface of a cylindrical opening of a torque receptor comprising a shaft that rotates around a center axis, the shaft having at least two cam driving surfaces that are spaced substantially equally from the center axis and that are adapted to transmit torque applied to the shaft; at least two gripping shells having axial end portions and convex external gripping surfaces that have a cylindrical convex profile and that slidingly engage the cylindrical concave internal surface, the gripping shells further including internal cam follower surfaces that are adapted to be engaged by the cam driving surfaces so that torque applied to the shaft is transmitted from the cam driving surfaces to the internal cam follower surfaces so that the center axis of the shaft is substantially aligned with a center axis of the cylindrical opening; retaining recesses that axially and radially retain the gripping shells on the coupler adjacent the shaft and that allow the gripping shells to move freely in a radial direction and that allow the gripping shells to automatically engage the cylindrical concave internal surface of the cylindrical opening. 
   The present invention may further comprise a wrench for engaging an internal surface of a pipe and turning the pipe in either direction comprising a shaft that rotates around a center axis, the shaft having at least two cam driving surfaces that are spaced substantially equally from the center axis for transmitting torque applied to the shaft; at least two gripping shells having external convex gripping surfaces that are cylindrically shaped, the external convex gripping surfaces disposed on the gripping shells to slidingly engage the cylindrically shaped concave internal surface of the pipe, the gripping shells further including internal cam follower surfaces that are designed to be engaged by at least two cam driving surfaces on the shaft so that the torque applied to the shaft is transmitted to the at least two gripping shells from the center axis in a direction that is substantially transverse to the center axis so that the gripping shells apply force to the cylindrically shaped concave internal surface of the pipe and the center axis of the shaft is substantially aligned with a center axis of the pipe; a retainer that engages the gripping shells to retain the gripping shells on the wrench adjacent the shaft and allows the shells to freely move, without being biased, in a direction that is transverse to the center axis to automatically open and engage the internal surface of the pipe. 
   The present invention may also further comprise a method of fabricating a wrench that is adapted to engage the internal surface of a pipe to turn the pipe comprising providing a shaft adapted to receive a torque to turn the pipe around a center axis of the shaft, the shaft having at least two cam surfaces that are adapted to transmit torque applied to the shaft; providing at least two gripping shells each having at least one external gripping surface and at least one internal cam follower surface, the external gripping surface having a convex cylindrical shape that slidingly engages the concave cylindrically shaped internal surface of the pipe, and the internal cam follower surface being adapted to engage at least one of the cam driving surfaces on the drive shaft so that torque applied to the shaft is substantially symmetrically transmitted to the at least two gripping shells from the shaft in a direction that is substantially transverse to the center axis so that the gripping shells apply force to the concave cylindrically shaped internal surface of the pipe and the center axis is substantially aligned with a center axis of the pipe; and providing a retainer that engages the gripping shells to retain the gripping shells on the wrench adjacent the shaft and allows the shells to move freely, without being biased in the substantially transverse direction so that the shells automatically open and engage the internal surface of the pipe. 
   The present invention may also further comprise a method of turning a pipe with an internal pipe wrench comprising gripping a concave cylindrical internal surface of the pipe with one or more gripping shells of the internal pipe wrench, the gripping shells having convex gripping surfaces that are cylindrically shaped to slidingly engage the concave cylindrical internal surface of the pipe, the gripping shells further including cam follower surfaces that are adapted to be engaged by cam driver surfaces of a cam driver that apply torque to the cam follower surfaces causing the gripping shells to expand and engage the internal surface of the pipe so that the pipe is substantially aligned with the center axis, the gripping shells retained on the internal pipe wrench with a retainer that allows the gripping shells to move freely, without being biased so that the gripping shells automatically open and engage the concave cylindrical internal surface of the pipe whenever torque is applied to the cam driver; applying a torque in either direction to the cam driver to cause the gripping shells to expand and engage the cam follower surface of the gripping shells; and turning the pipe in the direction of the torque. 
   The present invention may also further comprise a coupler that is adapted to engage a cylindrical concave internal surface of a cylindrical opening of a torque receptor comprising a shaft that rotates around a center axis, the shaft having at least two cam driving surfaces that are spaced substantially equally from the center axis and that are adapted to transmit torque applied to the shaft; at least two gripping shells having axial end portions and convex external gripping surfaces that have a cylindrical convex profile and that slidingly engage the cylindrical concave internal surface, the gripping shells further including internal cam follower surfaces that are adapted to be engaged by the cam driving surfaces so that torque applied to the shaft is transmitted from the cam driving surfaces to the internal cam follower surfaces so that the center axis of the shaft is substantially aligned with a center axis of the cylindrical opening; retaining recesses that axially and radially retain the gripping shells on the coupler adjacent the shaft and that allow the gripping shells to move freely in a radial direction and that allow the gripping shells to automatically engage the cylindrical concave internal surface of the cylindrical opening; a driver connected to the shaft, the driver having a cylindrical collar portion that is substantially aligned with the center axis, the cylindrical collar portion having an interior cylindrical surface that is adapted to receive the torque receptor and provide structural support for the torque receptor to prevent ovaling and structural failure of the torque receptor. 
   The present invention may also further comprise a wrench for engaging an internal surface of a pipe and turning said pipe in either direction comprising a shaft that rotates around a center axis, the shaft having at least two cam driving surfaces that are spaced substantially equally from the center axis for transmitting torque applied to the shaft; at least two gripping shells having external convex gripping surfaces that are cylindrically shaped, the external convex gripping surfaces disposed on the gripping shells to slidingly engage the cylindrically shaped concave internal surface of the pipe, the gripping shells further including internal cam follower surfaces that are designed to be engaged by at least two cam driving surfaces on the shaft so that the torque applied to the shaft is transmitted to the at least two gripping shells from the center axis in a direction that is substantially transverse to the center axis so that the gripping shells apply force to the cylindrically shaped concave internal surface of the pipe and the center axis of the shaft is substantially aligned with a center axis of the pipe; a retainer that engages the gripping shells to retain the gripping shells on the wrench adjacent the shaft and allows the shells to freely move, without being biased, in a direction that is transverse to the center axis to automatically open and engage the internal surface of the pipe; and a driver connected to the shaft, the driver having a cylindrical collar portion that is substantially aligned with the center axis, the cylindrical collar portion having an interior cylindrical surface that is adapted to receive the pipe and provide structural support for the pipe to prevent ovaling and structural failure of the pipe. 
   The advantages of the present invention include time savings, ease of use and the ability to employ the present invention in tight spaces where other devices for turning the pipe or torque transmitter, such as a driveshaft could not be used, such as with a standard external pipe wrench. The coupler can be employed with a ratchet which saves time and allows the coupler to turn pipes and torque transmitters in spaces that may be too tight for a standard external pipe wrench or other drive couplers. The compactness of the coupler, and the fact that the coupler accesses the pipe from a different direction and in a different way than a standard external pipe wrench or drive copuler, allows the coupler to be effectively used in situations that are not conducive to other techniques of handling pipes or torque transmitters. In addition, the coupler can be used where nipples cannot be accessed by a pipe wrench, or where threads on short nipples cannot be marred in either the loosening or tightening process. Further, the coupler can be used to remove broken off pipes that are threaded into a fitting, which may frequently occur with the use of plastic pipes. Also, standard ratchet extension bars can be used with the coupler to access hard to reach locations to both tighten and loosen pipe. The present invention is simple in design has a few mechanical moving parts and operates automatically to grip the internal surface of a pipe in either direction to allow either tightening or loosening of the pipe or driving of a driveshaft in either direction. The weight of the jaws or shells of the wrench of the present invention helps the jaws to automatically open and engage the internal surface of the pipe or torque transmitter. Further, the resisting inertia of the jaws, due to the mass of the jaws, helps to open the jaws when the cam first starts turning. Further, the coupler is designed so that the pipe end engages the face of the shells or jaws of the coupler which generates friction between the pipe and the jaws to help the jaws stay in a stationary position as the cams function to open the jaws. As a result, the coupler is simple and easy to use due to the elegance of the design. Another embodiment of the coupler can be used as an alignment device to align pipes for butt end welding. Further, the coupler can be used for power drive applications that allows a receptor unit (torque transmitter) to be driven in either direction. Collars prevent ovaling of the driveshaft. 
   The coupler can also be used in conjunction with a ring placed on the outside of the pipe to prevent the pipe from ovaling, such as may occur with thin wall pipes or shafts, and to maintain the structure and rigidity of a rusted pipe or shaft. Another advantageous feature of the coupler is that the shells include depressed regions that provide room for ridges that may typically be formed at the end of cheaply constructed pipes, such as cheaply made nipples. This allows the spline surfaces or other rough surface of the shell to engage the inner surface of the nipple without interference from the ridges that are formed by these cheaply made nipples. 
   Another advantage of the coupler is that the shoulders at the rear portion of each shell engaging section butt against the end of the nipple which causes the shells to rotate with the nipple and create movement between the shaft and the shells so that the shells engage the inner surface of the nipple. To assist in this function, a frictional surface can be created on the shoulder portions such as serrations, knurling or other frictional surface. As such, the butt end of the nipple engages the shoulder of the shells with a greater coefficient of friction to thereby enhance this advantageous functionality of the present invention. In addition, various types of frictional material can be used on the outer portions of the shells as well as the shoulder portions including serrating, splines, diamond grip surfaces, rubber grip surface, knurling, et cetera. In some applications, even a smooth surface may be advantageous because of the nature of the pipe that is to be turned. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, 
       FIG. 1  is a perspective view of one embodiment of the present invention. 
       FIG. 2  is a perspective view of one embodiment of the invention. 
       FIG. 3  is a cross-section view of one embodiment of the inventive pipe wrench taken normal to the axis of a pipe, with the wrench in the collapsed position. 
       FIG. 4  is a cross-section view of one embodiment of the inventive pipe wrench with the wrench in an engaged position. 
       FIG. 5  is a cross-section view of an alternative embodiment of the invention illustrating a pipe wrench containing one gripping shell. 
       FIG. 6  is a cross-section view of another alternative embodiment of the invention illustrating a pipe wrench containing six gripping shells. 
       FIG. 7  is a semi-exploded view of one embodiment of the invention with one of the gripping shells exploded from the assembly. 
       FIG. 8  is a fully exploded view of the embodiment of FIG.  7 . 
       FIG. 9  is a cross-section view of the embodiment of  FIG. 7  taken parallel to the axis of the pipe. 
       FIG. 10  is a perspective view of an embodiment of the present invention driven by an automatic pneumatic ratchet wrench. 
       FIG. 11  is a cross-sectional view of one embodiment of the pipe wrench of the present invention that is constructed with a common wrench socket. 
       FIG. 12  is a cross-sectional view of another embodiment of the wrench of the present invention using a common wrench socket. 
       FIG. 13  is an illustration of a multi-stage wrench in accordance with the present invention that uses splines around the entire gripping surface of the shells. 
       FIG. 14  illustrates a multi-stage wrench that uses rough surfaces around the entire periphery of the shells. 
       FIGS. 15 ,  16 ,  17  and  18  illustrate single stage pipe wrench in accordance with the present invention of different sizes. 
       FIGS. 19 ,  20 ,  21  and  22  illustrate single stage wrenches in accordance with the present invention having various types of gripping surfaces. 
       FIG. 23  is a perspective view illustrating the indentations in a multi-stage pipe wrench in accordance with the present invention that account for ridges on cheaply built nipples. 
       FIG. 24  is a cut-away view illustrating the manner in which indentations in the shells account for ridges formed in cheaply formed nipples. 
       FIG. 25  is a perspective view of a multi-stage wrench in accordance with the present invention illustrating the indentation portions. 
       FIG. 26  is a cut-away view of the wrench of the present invention in an engaged position illustrating the manner in which splines may cover the entire gripping surface of the shells. 
       FIG. 27  is a partially exploded view of the wrench of the present invention that employs a frictional surface on the shoulders of each of the gripping surfaces. 
       FIG. 28  is a perspective view of an alternative embodiment of the present invention that is used to align pipes for butt-welding. 
       FIG. 29  is another alternative embodiment of the present invention illustrating the manner in which the present invention may be used as a power-coupling unit. 
       FIG. 30  is a perspective view of the manner in which a drive shaft may be removably coupled to a socket. 
       FIG. 31  is a perspective view illustrating the manner in which a ring may be employed with the present invention. 
       FIG. 32  is a cut-away view illustrating the manner in which a ring may be used in conjunction with the present invention. 
       FIG. 33  is a cross-sectional view of another embodiment of the invention. 
       FIGS. 34-37  are perspective views of another embodiment of the invention illustrating the manner in which a pipe can be engaged beyond a threaded portion to prevent ovaling of the pipe. 
       FIG. 38  is a cross-sectional view of another embodiment of the invention that includes a collar for preventing ovaling. 
       FIG. 39  is a cross-sectional view of another embodiment of the invention that shows a collar portion of the driver that is used to further prevent ovaling of the pipe. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a perspective view of one embodiment of the invention illustrating a pipe wrench  100  that is engaged by a common ratchet wrench  102 . The wrench  100  is shown prior to being inserted into pipe  104  that is to be driven into fitting  106 . As shown in  FIG. 1 , the wrench  100  has three staged portions of each of the jaws or shells that are capable of engaging the interior surface of three different sizes of pipes. Since the wrench  100  is constructed to engage the inner surface of pipes, such as pipe  104 , the size and spacing of each of the engaging surfaces of the jaws of the wrench  100  is made for a particular size of inner diameter (ID) pipe. For example, black pipe that is used for gas connections has standard inner diameters for different size pipes. For example, ½ inch black pipe has a standard inner diameter that may be engaged by the smallest portion  108  of the jaws of the wrench  100 . A ⅝ inch black pipe may have an inner diameter that is engaged by the middle portion  110  of the wrench  100 . Further, a ¾ inch pipe may have an inner diameter that is engaged by the large portion  112  of the wrench  100 . Alternatively, the present invention may be used with plastic pipe or other types of pipe that may have different inner diameters for the same size of outer diameter pipe. In this case, different sizes may be provided for each of the stages  108 ,  110 ,  112  of the wrench  100 . 
     FIG. 2  is a perspective view similar to  FIG. 1 , wherein the pipe wrench  100  is being driven by a common ratchet wrench  102 , and is fully engaged with the interior surface of pipe  104  that is to be driven into fitting  106 . In this view, it is apparent how little space is occupied by the pipe wrench  100 , which is barely visible outside of the pipe  104 . In this embodiment, a common ratchet wrench  102  is used to drive the pipe wrench  100 . For areas where access is limited, common ratchet wrench extensions and other common ratchet wrench drivers can be used. 
     FIG. 3  shows a cross-sectional view of the wrench illustrated in  FIGS. 1 and 2  that is inserted into a pipe  300  prior to engagement.  FIG. 3  illustrates the drive shaft  302 , first gripping shell or internal jaws  304 , and second gripping shell or internal jaws  306 . For the purposes of simplicity, the gripping shells, which are also referred to as internal jaws, are referred to throughout the remainder of this description as gripping shells. It should be understood that the term gripping shells should not be interpreted to limit the scope of this invention. The gripping shell  304  has external gripping surface  308  and internal cam surface  310 , which is touching the cam surface  312  of drive shaft  302 . 
     FIG. 4  shows a cross-sectional view of the wrench illustrated in  FIGS. 1-3  showing engagement of the wrench on the interior surface  400  of pipe  300 .  FIG. 4  illustrates the drive shaft  302 , first gripping shell  304 , and second gripping shell  306 . The drive shaft  302  is rotated to the point that it forces gripping shells  304  and  306  to press against the internal surface  400  of the pipe  300 . The torque to the drive shaft  302  is applied in a counter clockwise motion. In the embodiment shown in  FIGS. 1-4 , the outer surface of gripping shell  304  has a radius  402  that is smaller than the internal radius of the pipe  400 . This design allows the gripping teeth  308  to grip the internal surface  400  of the pipe  300  over a wide area while not distorting the internal shape of the pipe  300 . The gripping teeth  308  can be made from hardened steel or any other material suitable for gripping the interior surface  400  of pipe  300 . 
   Other shapes and materials can be used to grip the internal surface  400  of the pipe  300  illustrated in  FIGS. 1-4 . For example, the teeth  308  could be replaced with a tacky rubber surface, which will provide an adequate amount of grip yet not mar the internal surface of the pipe. Other malleable materials, such as a soft metal or plastic can be used if the internal surface  400  is not to be damaged. In fact, any type of gripping surface can be used in accordance with the present invention that is capable of transmitting a driving torque to the inner surface of a pipe or other object. For example, a sticky surface can be used or surfaces such as sandpaper or a knearled surface can be used to engage the inner surface of the pipe. The only constraint is that enough friction is created between the inner surface of the pipe or other object and the gripping shells to transmit the driving torque force to the pipe or other object this can be accomplished through the use of various shapes or substances, or a combination of the two. 
   Further, the present invention can be used with any desired type of pipe  300 . Pipe may comprise metal pipe, plastic pipes of various types, tubes, rigid conduit, etc. In addition, the present invention can be used on objects other than pipes to transmit a rotational torque to the object. Hence, the term pipe should be interpreted to include any type of device that can be engaged by the internal jaws/gripping shells of the present invention. Also, the shapes of the gripping shells  304  and  306  may be selected to engage the internal surface of a round hole or other shapes as well. For those applications where the object to be turned is not a round hole, such as if the hole were square or elliptical, the shapes of the gripping shells  304  and  306  may be changed appropriately. Those skilled in the art may select many different gripping materials and shapes pertaining to their application. Further, the torque transmitted to the pipe can be used for various purposes such as motive driving torque, tightening or loosening threads, removing broken pipes, etc. For example, the present invention can be used where a single power source is used to drive various different pieces of equipment, and the power source can be easily engaged and disengaged from the equipment using a drive coupler in the form of a tube or pipe. This is more fully illustrated in  FIG. 30 , described below. In addition, the present invention can be used with large threading equipment that is used to thread pipe. Rather than have the large jaws that grasp and turn the pipe, the present invention can be used to handle the pipe during the threading process. 
     FIG. 4  further illustrates the cam mechanism that comprises internal cam surfaces  310  and  404  of the gripping shells  304  and  306 , respectively, and the drive shaft cam surfaces  312  and  406 . In the embodiment illustrated in  FIG. 4 , the cam surfaces are flat surfaces. However, a curved surface may be selected to change the ratio of circumferential expansion verses the torque applied to the pipe  300 . For example, a sharply rising cam surface will not provide as much circumferential expansion per turning torque as would a slowly rising cam surface. 
   If the pipe  300  is too large for the wrench to turn, the gripping shells  304  and  306  will extend until the point where the highest point of the drive shaft  302  passes over the internal cam surfaces  310  and  404 . In this case, the operator of the pipe wrench must select a different diameter gripping shell  304  and  306  to use. The size of the gripping shell and the size of the cam are designed to engage a certain percentage of the wall thickness of the pipe. For example, the “throw” of the shells may be designed to be 75% of the wall thickness of the pipe  300  to ensure that rusted pipes can be fully engaged. The size of the shells is also designed so that the unit can be easily inserted into the pipe without the necessity of manually closing the shells. 
   The pipe  300  as illustrated in  FIGS. 1-4  represents a conventional plumbing pipe. For the purposes of this specification, the term pipe shall comprise conventional plumbing pipes, but also any device or article with an internal hole into which the inventive wrench can be inserted and caused to turn the device or article. An example would be the assembly of table legs in the manufacture of furniture, or the assembly of automotive components by engaging only an internal hole to screw the component to the assembly. 
     FIG. 5  illustrates an embodiment of the invention comprising a single gripping shell. The single gripping shell design comprises a drive shaft  500  and a single gripping shell  502 , where one external surface  504  of the drive shaft  502  rests against the internal diameter  506  of the pipe  508 . The drive shaft  502  has torque applied in a counter clockwise direction. The advantages of this design are the minimal number of moving parts and the simplicity of the design. 
     FIG. 6  illustrates an embodiment of the invention comprising six gripping shells.  FIG. 6  illustrates the pipe  600 , the drive shaft  602 , and six gripping shells  604 ,  606 ,  608 ,  610 ,  612 , and  614 . The drive shaft  602  is shown turned so that the drive shaft cam surface  616  is forcing gripping shell  604  outward by pushing on its cam surface  618 . The other gripping shells  606 ,  608 ,  610 ,  612 , and  614  are similarly extended. The drive shaft  602  has torque applied in a counter clockwise direction. One of the advantages of a multiple gripping shell design is that the pipe is uniformly and evenly loaded with the circumferential expansion force of the gripping shells. By using a large number of gripping shells, the pipe is much less likely to deform or “egg” than when lesser numbers of gripping shells are used. For the remainder of the discussion, an embodiment  100  with two gripping shells will be discussed. It is readily obvious to one skilled in the art that all of the features discussed below may be applied to embodiments with any number of gripping shells. 
     FIG. 7  is a perspective view of a dual shell embodiment of the invention  100  in a semi-exploded state.  FIG. 7  illustrates a drive socket  700 , a first gripping shell  702 , a second gripping shell  704 , a drive shaft  705 , an end cap  706 , and an end cap retaining screw  708 . Recess  710  in the drive socket  702  forms a retainer into which fits a bottom lip  712  of the second gripping shell  706 . A similar lip  714  fits into a recess (shown in  FIG. 9 ) on the underside of retaining cap  706 . The retainer keeps the gripping shells attached to the wrench  100  when the wrench  100  is being stored or transported. The recess  714  and its counterpart on the underside of retaining cap  706  are both selected so that the gripping shells are able to expand when the center drive shaft  700  is turned. A gap is selected between the recess  710  and the lip  712  such that sufficient space is provided so that the drive shaft  700  can turn freely while the gripping shell  704  slides over the respective cam surfaces without binding between recess  710  and lip  712 . An excess amount of space is not necessary since only enough space is needed to allow the drive shaft to completely turn with respect to the shells. This spacing, of course, is dependent upon the amount of throw that has been designed into the unit. 
   As also shown in  FIG. 7 , the gripping shell  704  contains three gripping surfaces,  716 ,  718 , and  720 , each successively increasing in diameter. This embodiment is designed to turn three standard size pipes. When the largest size pipe is selected to be turned, the wrench  100  is slid into the open end of the pipe until the flange  722  seats against the end of the pipe. The flange  722  acts in several ways. One is to position the wrench  100  so that the gripping surface  720  fully engages the pipe to be turned. A second purpose of the flange  722  is to align the pipe wrench  100  with the axis of the pipe to be turned. A third purpose of the flange  722  is to provide a frictional surface  724  for the gripping shell  704  to engage the pipe. The face or shoulder  724  of the flange  722  engages the butt end of the pipe which causes friction to be created between the butt end of the pipe and the face  724 . This friction helps to keep the gripping shells in a stationary position and resist rotation as the cam opens the shells so that the gripping shells engage the interior surface of the pipe. In other words, surface  724  functions to provide some friction that overcomes the frictional force of the cam mechanism and to allow the cam mechanism to force the gripping shell  704  outwardly until it engages the pipe to be turned. Frictional surfaces can be designed into the shoulder portions as shown in FIG.  28 . The existence of the shoulder is particularly useful if a hand device is used to drive the pipe wrench  100 , such as with a hand operated ratchet wrench as in  FIG. 1 , a common pipe wrench as in  FIG. 11 , an integral handle that is part of the drive shaft, or other hand operated device. For powered devices, such as with a pneumatic powered ratchet, as shown in  FIG. 12 , an electric drill, or other powered torque devices, the centripetal force provided by the mass of the gripping shells  702  and  704  may also help to initiate the engagement of the inner diameter of the pipe and begin the cam action. 
   For the smaller diameter-gripping surface  718  shown in  FIG. 7 , the surface or shoulder  726  provides the same functions as surface or shoulder  724  does for gripping surface  720 .  FIG. 7  illustrates an embodiment with three gripping surfaces,  716 ,  718 , and  720 . Alternatively, embodiments may contain between one and a multitude of gripping surfaces. The gripping surfaces  716 ,  718 , and  720  are designed to grip the internal diameter of a pipe that has a constant diameter. For turning pipes or other articles that have a tapered or other specially shaped bore, the gripping surfaces may be shaped to match the internal surface of such an article. 
     FIG. 8  shows a perspective view of a fully exploded assembly  100 . The assembly  100  comprises a drive socket  700 , first gripping shell  702 , second gripping shell  704 , retaining cap  706 , and retaining cap screw  708 . An alternative embodiment may include a retaining cap that incorporates an integral threaded feature and eliminates the screw  708  from the assembly. The drive socket  700  comprises a driven end  800  and the drive shaft  802 . The drive shaft  802  contains curved surfaces  804  and  806  and flat surface  808  and  810 . The cam surface  810  rests against gripping shell cam surface  812  when the gripping shells  702  and  704  are retracted. 
     FIG. 9  illustrates a cross-sectional view of the inventive pipe wrench  100  taken parallel to the axis of the pipe.  FIG. 9  illustrates a drive shaft  700 , a first gripping shell  702 , a second gripping shell  704 , a retaining cap  706 , and a retaining cap screw  708 . The drive socket and drive shaft are incorporated into one piece as shown in FIG.  9 . These can be made into two separate pieces if desired as illustrated in  FIGS. 11 ,  12  and  30 . The gripping shell  704  has upper retaining lip  900  that is retained by the lip  902  of retaining cap  706 . The retaining cap lip  902  of the retaining cap  706  forms a recess that retains the retaining lip  900  of the gripping shell  704 . The gap between the drive shaft  700 , the upper retaining lip  900  and the retaining cap lip  902  is selected so that the drive shaft can turn and the cam mechanism push the gripping shell  704  outward to its fullest extent while still maintaining a slight gap between lips  900  and  902 . Alternative designs exist for retaining the gripping shells  702  and  704  onto the drive shaft  700 . For example, the shells may be constrained axially by mechanical stops along the axis of the drive shaft  700 , or by a hoop of wire, a ring such as a metal or rubber O-ring that rides in the slot  904  or other locations. Other retention designs are well within the purview of those skilled in the art. 
     FIG. 10  illustrates an embodiment of the inventive pipe wrench  100  being driven by a pneumatic ratchet  1000 . The wrench  100  is being used to turn chrome plated pipe  1002  into a chrome plated fitting  1004 . The purpose of  FIG. 10  is to demonstrate alternative methods of turning the pipe wrench  100 . 
     FIG. 11  illustrates an embodiment of the inventive pipe wrench that is constructed with a common wrench socket  1102 . The drive shaft  1100  is driven by a common wrench socket  1102  and has gripping shells  1104  and  1106  captured by a retaining cap  1108 . The drive shaft  1100  can be locked into the wrench socket  1102  by various means including adhesive, press fitting, brasing, soldering, etc. 
     FIG. 12  illustrates an alternative embodiment similar to the embodiment illustrated in FIG.  11 . In a manner similar to  FIG. 11 ,  FIG. 12  illustrates a single staged portion of the gripping shells. A socket drive  1202  engages the drive shaft  1200  and may be retained in the drive socket  1202  in various ways including friction fitting, O-ring fitting, as described in  FIG. 30 , or any desirable manner. Shells  1204  and  1206  have shoulders  1210  and  1212  respectively that engage the butt end of the pipe, as described above. As shown in  FIG. 12 , the gap between the lips  1218 ,  1220  and the inner surface  1222  of the cap is sufficient to allow the cam to have sufficient throw to completely rotate without breaking the cap  1208 . In addition, the surface between the cap and the lips  1218 ,  1220  should have low friction to allow the shells  1204 ,  1206  to easily rotate against the cap  1208 . 
   Similarly, the lips  1214 ,  1216  have a gap that is defined by the drive socket  1202  that is substantially equal to the gap between the lips  1218 ,  1220  and the cap  1208 . Also, the surface between the lips  1214 ,  1216  and the drive shaft  1200  is a low friction surface to, again, allow the shells to rotate freely. The shoulder surfaces  1210 ,  1212  may be desirable to be made as high friction surfaces, in the manner described herein, so that the butt end of the nipple will engage and rotate the shells  1204 ,  1206  with respect to the drive shaft  1200 . 
     FIG. 13  is an illustration in which the splines  1300 ,  1302 ,  1304  extend around the entire surface of each of the shells of the device. This feature is also shown in FIG.  26 . 
     FIG. 14  illustrates rough surfaces  1400 ,  1402  and  1404  that are formed into the face of the shells, as opposed to using the splined surfaces illustrated in FIG.  13 . The frictional surfaces  1400 ,  1402  and  1404  can be diamond grip surfaces, knurled surfaces, cut surfaces, or any desired surface to create friction between the inner surface of the pipe and the shells. In some instances, softer metal materials or rubber or other coatings may be desired to be placed on the gripping shells. Further, the pipe may be made of a material that is a soft gripping material so that smooth or only slightly rough surfaces are needed to engage the inner surface of the pipe. 
     FIGS. 15 ,  16 ,  17  and  18  illustrate four different single stage devices that employ various features of the present invention. For example,  FIG. 15  illustrates a half-inch device, while  FIG. 16  illustrates a five-eighths inch device.  FIG. 17  illustrates a three-quarter inch device, while  FIG. 18  illustrates a one-inch device. These figures illustrate that various size units may be provided to customers as single staged units and multi-stage units in a complete set. For example, there may be applications in which a multi-stage unit cannot be used because of the clearance required. Hence, single-stage units must be employed. 
     FIGS. 19 ,  20 ,  21  and  22  illustrate various types of surfaces that can be used on the single-stage devices. For example,  FIG. 19  illustrates that a smooth surface can be used on the shells. This may be desirable for certain applications where soft materials are being employed for the pipe. As illustrated in  FIG. 20 , a rough surface can be formed such a knurled surface, a sand surface, a cut surface, or any other desired type of surface.  FIG. 20  illustrates that a rubber coating, or other type of coating, can be applied to the surface of the shell to grip the pipe.  FIG. 22  illustrates a diamond grip surface  2200  for gripping the inner surface of the pipe. 
     FIG. 23  illustrates another advantageous feature that can be employed with respect to the present invention. As shown in  FIG. 23 , a nipple  2300  may be a low quality nipple in which a ridge  2302  is formed that protrudes inwardly as a result of the formation process of the nipple  2300 . The wrench  2300 , as disclosed above, has shells that have an indentation  2306  that accommodate the ridge  2302 , as more fully illustrated in FIG.  24 . 
     FIG. 24  is a cross sectional view of a nipple  2400  that is engaged by a shell  2404 . As shown in  FIG. 24 , the nipple  2400  is an inexpensive nipple that has a ridge  2402  that protrudes inwardly towards the inner diameter of the nipple  2400 . The protrusion or ridge  2402  is generated through low quality production methods for forming the nipple  2400 . This has become somewhat commonplace in inexpensive nipples. The shell  2404  has an indentation  2406  to accommodate the protrusion  2402 . In this manner, the gripping surface  2408  of the shell  2404  can engage the inner surface  2410  along an extended region without interference from the ridge  2402 .  FIG. 24  also illustrates the frictional surface  2414  that is formed in the shoulder  2412  of the shell  2404 . Again, the butt end  2416  of the pipe is engaged along the shoulder  2412  as the wrench is inserted into the nipple to cause the shell  2404  to rotate with the nipple  2400  thereby causing the drive shaft and the cams to open the shell  2404  and engage the inner surface  2410  of the nipple  2400  by the surface  2408  of the shell  2404 . 
     FIG. 25  is a further illustration of a multistage wrench having indentations  2500 ,  2502  and  2504  for each stage to accommodate the ridges that may be formed on the pipe butt end. 
     FIG. 26  is similar to  FIG. 4  but illustrates that the splined surfaces  2600  can be formed along the entire surface of the shells  2602  and  2604 . This may assist in engaging the inner surface of the pipe. 
     FIG. 27  is an exploded view diagram of a multistage wrench, in accordance with the present invention, that illustrates the frictional surfaces  2700 ,  2702  and  2704  on the shoulders of shell  2705 , and frictional surfaces  2706 ,  2708  and  2710  on the shoulders of shell  2712 . Again, these frictional surfaces engage the butt end of the pipe when the wrench is inserted into the pipe and assists in causing the shells to rotate with the pipe so that the drive shaft  2714  can rotate with respect to the shells  2705 ,  2712 .  FIG. 27  also illustrates the indentations between each of the engaging surfaces of the multistage device. 
     FIG. 28  illustrates another embodiment of the invention in which two pipes  2800 ,  2802  can be aligned to form a butt weld  2804 . As shown in  FIG. 28 , the alignment device  2810  is inserted in the pipes  2800 ,  2802  so that engaging surfaces of the shell expand and align the pipes  2800 ,  2802  in proper orientation so that the butt ends are aligned. In this fashion, a butt weld  2804  can be made as a result of the proper alignment of the two pipes  2800 ,  2802 . The alignment device  2810  includes a socket drive  2812  that is engaged by an extension  2814 . In aligning the pipes, the alignment device is inserted using the extension  2814  until it is aligned with the gap between the two pipes  2800 ,  2802 . The pipes  2800 ,  2802  are then forced against each other so that the butt ends are aligned. At the same time, the extension  2814  is rotated in either direction to expand the shells  2806 ,  2808  so that the shells engage the inner surfaces of both of the pipes  2800 ,  2802  and align those pipes for butt-welding. 
     FIG. 29  illustrates another application of the concepts of the present invention. As shown in  FIG. 29 , a machinery drive shaft  2900  may have an opening to engage the gripping unit  2902 . The gripping unit  2902  may be attached to a drive shaft, such as a tractor drive shaft  2904 . The gripping unit  2902  operates in the same fashion as described above. The machinery drive shaft  2900  may also have splines such as the splines  2806  for effective engagement between the machinery drive shaft  2900  and the gripping unit  2902 . The advantage of the device illustrated in  FIG. 29  is that power can be coupled between drive shafts for machinery and power units in a simple and easy fashion that allows the drive shaft to rotate in either direction and to be engaged and disengaged in a simple and easy fashion. 
     FIG. 30  illustrates the manner in which a drive socket  3000  can accommodate a separate drive shaft  3010  so that the drive shaft  3010  is engaged in the socket  3000  in a removable manner. As shown in  FIG. 30 , indentations  3002  are formed along each of the inner surfaces of the socket  3000 . The ring  3004  is pushed into the gaps between plates  3006 ,  3008 . Plates  3006 ,  3008  are formed to fit within the opening of the socket  3000 . The O-ring  3004  extrudes partially from the flat surfaces of the plates  3006 ,  3008  and engages the indentations  3002  so that the drive shaft unit  3010  is removably engaged within the socket  3000 . This is advantageous in that if a drive shaft  3010  is broken it can be easily dismantled from the socket  3000  and replaced without replacing the entire unit including the socket portion  3000 . The drive shaft and other parts associated with the drive shaft, such as the plates  3006  and  3008 , may be tempered to cause slow failure of the drive shaft  3010 . This prevents the user from possibly breaking fingers or hands during the use of the device. The replaceable drive shaft  3010  can be easily disconnected from the socket  3000  as a replaceable part. 
     FIG. 31  illustrates a ring  3100  that can be used with the present invention. Ring  3100  is a separate ring that has an internal opening that will fit around the outer diameter of the pipe. The ring  3100  provides structural rigidity for the pipe and will allow pipes such as thin wall pipes or pipes that have been corroded to maintain a round shape while the wrench of the present invention is utilized. In other words, the ring  3100  prevents the pipe from falling apart or taking on an oval shape while the wrench is being used which may detract from the effectiveness of the wrench of the present invention. 
     FIG. 32  is a cut away illustration for the manner in which the ring  3200  may be employed. As shown in  FIG. 32 , the ring  3200  is placed over the outer surface of the nipple  3202 . The ring  3200  fits over the outer surface of the nipple  3202  which has a specified outer diameter. The ring  3200  is formed of a material having a thickness to provide sufficient rigidity to prevent the nipple  3202  from ovaling which could prevent the wrench from engaging and turning the nipple  3202 . In other words, if the nipple  3202  obtains an oval shape the drive shaft may not have sufficient throw to cause the nipple to turn and pass over the center point of the drive shaft preventing the wrench of the present invention from turning the nipple  3202 . Ring  3200  also provides sufficient structural rigidity to allow corroded nipples or pipes  3202  from falling apart and preventing the wrench from turning the nipple. The ring  3200  may comprise different sized rings for different sized nipples and may be carried as a separate device to assist the user, as necessary. 
     FIG. 33  illustrates a cross-sectional view, that is similar to  FIG. 9 , but that shows an alternative design for the shells and retaining cap for the internal pipe wrench  3300 . As show in  FIG. 33 , shells  3302  and  3304  are constructed so that retaining lip  3305  engages the shaft  3306  and the cap  3307  in a different fashion than as shown in FIG.  9 . As shown in  FIG. 33 , the cap  3307  is attached to the internal pipe wrench  3300  by way of a bolt or screw  3308 . The bolt or screw is threaded into a threaded opening  3310  in the shaft  3306 . The threaded opening  3310  has a predetermined depth such that the bottom of the bolt/screw  3312  bottoms out on the bottom of the threaded opening  3314  at a predetermined depth. The cap  3307  then has a certain amount of vertical play between the bottom of the cap  3316  and shoulders  3318  of the shells  3302 ,  3304 . The bottom of the head of the bolt screw  3320  engages the upper surface of the cap  3307  to provide the amount of vertical play, as shown in  FIG. 33 , between the bottom of the cap  3316  and the shoulders  3318 . This vertical play allows the shells  3302 ,  3304  to easily rotate with respect to the shaft  3306 . The amount of vertical play, together with the length of the sidewalls of the cap  3307  prevent the shells from disengaging from the internal pipe wrench  3300  when the bolt/screw  3308  is tightened into position on the shaft  3306 . The retaining lip  3305  can be machined or cast into the shells  3302 ,  3304  and have the advantage of providing a very strong structure for retaining the shells  3302 ,  3304  on the internal pipe wrench  3300 . In other words, the retaining lip  3305  cannot be easily broken when the internal pipe wrench  3300  is in use. The throw provided by the cam surface of the shaft  3306  may either allow the shaft  3306  to completely rotate without causing structural failure of either the retaining lip  3305  or the cap sidewall  3322 , or may be designed for failure of the cap sidewall  3322  in certain instances. For example, it may be desirable to maintain a very small horizontal gap between the retaining lip  3305  and the cap sidewall  3322 . The internal diameter of pipes on which the internal pipe wrench  3300  may be used may have tight tolerances and require only a minimum amount of throw before engagement of the internal surface of the pipe. Hence, it may be advantageous to have close tolerances especially where insertion of the tool in an easy manner, such as in automated assembly, is desirable. Otherwise, the cap  3307  is designed to provide sufficient tolerance to allow the shaft  3306  to completely rotate without causing failure of the cap sidewall  3322 , or the retaining lip  3305 . 
     FIG. 34  is a perspective view of another embodiment of an internal pipe wrench  3400 . The internal pipe wrench  3400  has shells  3402  and  3404 , or may include three or more shells as disclosed above. The shells  3402 ,  3404  include a recessed portion  3408  which is slightly recessed from the teeth  3410  disposed on the shells  3402 ,  3404 . As disclosed above, a cap  3406  is used to retain the shells  3402 ,  3204  on the internal pipe wrench  3400 . The cap  3406  also has a diameter that is slightly less than the diameter of the teeth when the shells  3402 ,  3404  are in the closed position, as shown in FIG.  34 . The cap  3406  can also be equal to or even slightly larger than the diameter of the shells at the portion indicated by teeth  3410 . 
     FIG. 35  is a perspective view of an internal pipe wrench  3500  in an open position. As shown, the teeth  3506  extend beyond the cap  3504  and, of course, beyond the recessed portion  3502 . In this fashion, the teeth  3506  can engage the internal surface of a pipe. 
     FIG. 36  is a cut-away perspective view of an internal pipe wrench  3600  disposed in a pipe  3602 . As shown in  FIG. 36 , the recessed portion  3610  is sufficiently long to allow the teeth  3612  engage the internal surface of the pipe  3604  beyond the threaded portion of the pipe  3606 . It has been found through testing that removal of external portions of the pipe during the threading process weakens the pipe which can cause the pipe  3602  to oval if sufficient force is applied by an internal pipe wrench when the force is applied adjacent the threaded portion of the pipe  3606 . In the embodiment illustrated in  FIG. 36 , the teeth  3612  engage the internal surface  3604  of the pipe  3602  beyond the threaded portion of the pipe  3606  such that a greater force can be applied by the internal pipe wrench  3600  without ovaling the pipe. Of course, additional shells, such as shown in  FIG. 6 , and various cam configurations can be used to more evenly distribute the force about the pipe which also assists in preventing ovaling. 
     FIG. 37  illustrates the internal pipe wrench  3700  in an expanded orientation such that the teeth  3706 ,  3708  engage the internal surface  3702  of the pipe  3704  beyond the threaded portion of  3710  of the pipe  3704 .  FIG. 38  is a cross-sectional view of another embodiment of a coupler  3800 . As shown in  FIG. 38 , a driver similar to that shown in FIG.  32  and  FIG. 12  is shown. As indicated above, the coupler  3800  can be used as an internal pipe wrench, a coupler for driving a driveshaft, or any other desired use for coupling energy to a pipe, driveshaft or other similar device. As show in  FIG. 38 , a collar  3802  is coupled to the driver  3806  of the coupler  3800 . The collar  3802  can be press fit onto the body of the driver  3806 , or otherwise attached or connected in any desired fashion, such as by welding, brasing, gluing, soldering, or other forms of connection. The collar  3802  functions in the same manner as ring  3200  of FIG.  32 . Pipe/driveshaft,  3804 , is inserted between the collar  3802  and the jaws  3808  and  3810  of the coupler  3800 . The collar  3802  provides external support for the pipe/driveshaft  3804  to prevent ovaling of the pipe/driveshaft  3804 , in a manner similar to ring  3200  of FIG.  32 . Rather than providing a separate ring  3200 , such as illustrated in  FIG. 32 , the coupler  3800  provides a collar  3802  that is attached to the driver  3806  to eliminate the need for having a separate ring. Collar  3802  provides sufficient structural rigidity to allow corroded pipes from falling apart and preventing the coupler  3800  from turning a pipe and also prevents the pipe/driveshaft  3804  from ovaling. The inner diameter of the collar  3802  is sized to allow the pipe/driveshaft  3804  to easily slide between the jaws  3808 ,  3810  and the interior surface of the collar  3802 . 
     FIG. 39  illustrates another embodiment of a coupler  3900 . As shown in  FIG. 39 , the driver  3904  has a collar portion  3906  that forms part of the structural member of the driver  3804 . The collar portion  3906  functions in a manner similar to the collar  3802  of FIG.  38 . When a pipe/driveshaft  3902  is placed between the jaws  3908 ,  3910  and the collar portion  3906 , force exerted by the jaws  3908 ,  3910  will not cause the pipe/driveshaft  3902  to oval because of the structural rigidity provided by the collar portion  3906 . 
   The present invention therefore provides a unique tool that is easy to use and is elegant in design. The tool of the present invention allows the user to save time due to its simplicity and ease of use. The elegance of the design of the present invention allows the present invention to be used in tight places where ordinary pipe wrenches could not be employed. Further, the present invention prevents the marring of the external surface that may occur with the use of a pipe wrench such as the marring of pipe threads or a decorative outer surface of the object being turned. The present invention may also be used to extract broken pipes from a pipe fixtures which may typically occur with plastic pipes. The present invention works in an automatic fashion to apply torque in either a tightening or loosening direction. In other words, the gripping shells or jaws of the present invention engage the inner surface of the pipe without the use of springs or other mechanical devices by virtue of the design of the present invention. More specifically, the jaws of the present invention have a specific tolerance with respect to the inner surface of the pipe that allows the internal jaws to create sufficient friction with the internal surface of the pipe to keep the internal jaws stationary while the cam drives the internal jaws to an open position to transfer the torque to the jaws. The weight of the jaws and the fact that the jaws are unconstrained and allowed to float within the interior diameter of the pipe allows the jaws to engage the internal surface of the pipe and create the necessary friction to allow this process to occur. Further, the shoulders of each of the stages of the shell may engage the end portion of the pipe to further aid in maintaining the shells in a stationary position while the rotational torque of the drive shaft is applied to the shells to cause the shells to open and engage the inner surface of the pipe. This manner, the jaws or gripping shells can “automatically” engage the inner surface of the pipe, without the use of mechanical aids such as springs or other types of devices. 
   The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.