Abstract:
A welding implement and a method of extracting heat from a welding implement are disclosed. The welding implement includes one or more heat pipes which transfer thermal energy away from the torch head. A fluid, such as a shielding gas, may then convectively transfer the thermal energy away from the welding implement. The present invention thus provides a handheld welding implement that is compact, such that it can be used in confined spaces, and operated for longer periods of time, since the improved heat dissipation helps to maintain the welding implement at a temperature that an operator may hold.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates generally to welding implements and, more particularly, to cooling systems for welding implements. 
         [0004]    Welding is a fabrication process for joining two or more materials together by heating the materials and allowing them to flow together. In one type of welding, gas tungsten arc welding (GTAW), an electrical current is directed through a non-consumable tungsten electrode housed in a welding implement, such as a torch. The current arcs from the electrode to a work piece, which is placed within the welding circuit. The heat generated by the arc can cause the work piece to melt and form a weld. In other types of welding, such as gas metal arc welding (GMAW), a consumable filler wire is fed through a welding implement (i.e., a gun) as an electrical current heats the wire and the work piece. The filler wire melts and is deposited on the work piece, forming the weld. 
         [0005]    During the welding process, large amounts of heat are generated near the arc. This heat is transferred not only to the work piece to form the weld, but also to the components of the welding implement. In particular, the torch head can experience an extreme rise in temperature. Additionally, the current-carrying components of the welding implement can heat due to resistance heating. This rise in temperature can detrimentally affect the longevity and operability of the welding implement. 
         [0006]    Increasingly, the market is demanding welding implements that are smaller, for more maneuverability, but that can also carry more current, for increased weld depth penetration. These compact, high-powered welding devices require improved techniques of heat dissipation. Many attempts have been made to improve the transfer of heat out of welding implements, especially during extended use. 
         [0007]    Heat regulation in traditional welding implements has been addressed in a variety of ways with marginal results. For example, in TIG welding applications, the welding implement (i.e., torch) typically includes copper or brass current-carrying components that are designed to conduct heat away from the head of the torch toward the base of the torch body. Lower-temperature shielding gas is then passed over the torch body in an attempt to remove the heat from the torch via forced convection. To improve heat transfer, the component size has been increased to provide more heat carrying capacity. However, this approach results in a larger torch with less maneuverability. 
         [0008]    Another technique incorporates a torch handle or body having ribs or fins to help increase the rate of heat dissipation to the surrounding environment. Again, however, this approach leads to a larger torch making it less desirable for certain applications. 
         [0009]    Yet another cumbersome technique involves liquid-cooled welding implements. A liquid coolant is circulated via pump within the welding component where it comes into contact with and cools higher-temperature components. Distinct coolant passages are designed into the welding implement to maximize the heat removal. This technique has the obvious drawback of requiring an additional liquid coolant circulation system in addition to a larger welding-type gun to accommodate the cooling passageways. 
         [0010]    Therefore, it would be desirable to have a compact, self-contained welding implement capable of autonomously regulating the temperature of the welding implement during use. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention overcomes the aforementioned drawbacks by providing a welding implement and method that efficiently extracts heat from the welding implement via a closed system. Thus, the present invention effectively regulates the temperature of the welding implement during operation without substantially increasing the size of the welding implement or requiring any additional equipment to circulate coolant. 
         [0012]    In accordance with one aspect of the present invention, a welding implement is disclosed that is coupleable to a power supply that is capable of imparting thermal energy to the welding implement. The welding implement includes a body, a head, a heat pipe, and a fluid channel. The body has a proximal end and a distal end, the proximal end being coupleable to the power supply. The head is proximate the distal end of the body and receives the thermal energy imparted to the welding implement from the power supply. The heat pipe has a closed passage containing a working fluid in thermal communication with the head to extract at least a portion of the thermal energy from the head. The fluid channel extends over at least a portion of the heat pipe to receive a cooling fluid flowing from the proximal end toward the head. 
         [0013]    Variations may be made to this welding implement. The welding implement may further include a plurality of heat pipes. A thermal energy sink may contact at least a portion of the heat pipe. The casing of the heat pipe may be formed of a conductive material configured to carry a welding current. 
         [0014]    Additionally, the welding implement may include at least one input into the fluid channel located proximate the proximal end and at least one output located proximate the head to direct the cooling fluid toward the welding implement. There may be a handle having an inner surface that forms at least a portion of the fluid channel. 
         [0015]    In accordance with another aspect of the invention, a welding implement is disclosed that includes a torch having a proximal end and a distal end. The proximal end is adapted for connection to a power supply. The torch has a torch head located proximate the distal end of the torch. The torch head is adapted for holding an electrode. The welding implement also has a heat pipe that forms a closed passage extending substantially from the torch head toward the proximal end of the torch. The welding implement also includes a handle surrounding at least a portion of the torch and at least a portion of the heat pipe. A working fluid is captured in the closed passage of the heat pipe and migrates substantially between the torch head and the proximal end of the torch to transfer thermal energy away from the torch head. In some forms, this working fluid may include water, helium, mercury, sodium, ammonia, ethanol, and methanol. 
         [0016]    Variations may be made to this welding implement. For example, a thermal energy sink may contact at least a portion the heat pipe. If there is a thermal energy sink, at least one fin may extend from the thermal energy sink. The welding implement may further include a channel formed between the handle and the heat pipe or the thermal energy sink as well as include at least one passage into the channel to direct a fluid therethrough to extract thermal energy from the heat pipe, possibly through the thermal energy sink. The fluid may include at least one of a shielding gas and a liquid coolant. The welding implement may further include at least one passage extending from the channel toward the electrode to allow the fluid to pass from the channel. 
         [0017]    According to yet another aspect of the invention, a method for extracting heat from a welding implement is disclosed. Thermal energy is transferred from the torch head to the working fluid. At least a portion of the working fluid within the heat pipe is evaporated and is directed from a location in the heat pipe proximate the torch head to a location in the heat pipe proximate the proximal end of the torch. The thermal energy is then transferred from the working fluid in the heat pipe at a location proximate the proximal end of the torch. A fluid is directed about the heat pipe to extract thermal energy therefrom and condense the working fluid at the location in the heat pipe proximate to the proximal end of the torch. The fluid may include a shielding gas or a liquid coolant. The method may further include the step of transferring the thermal energy from at least a portion of a thermal energy sink attached to the heat pipe to the fluid to direct the thermal energy away from the portion of the thermal energy sink. The method may also include the step of wicking of the working fluid in the heat pipe back to a location proximate the torch head via a wick. 
         [0018]    Various other features of the present invention will be made apparent from the following detailed description and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]    The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
           [0020]      FIG. 1  an isometric view of a welding-type system incorporating the present invention; 
           [0021]      FIG. 2  is an exploded view of an example welding implement incorporating the present invention; 
           [0022]      FIG. 3  is a cross-sectional side view of an exemplary heat pipe; 
           [0023]      FIG. 4  is an isometric view of a torch in accordance with one aspect of the present invention; 
           [0024]      FIG. 5  is an isometric view of the torch of  FIG. 4  with the handle removed to reveal the interior components; 
           [0025]      FIG. 6  is a partial cross-sectional side view of the torch of  FIG. 4  along line  6 - 6 ; 
           [0026]      FIG. 7  is an isometric view of the torch in accordance with another aspect of the present invention; 
           [0027]      FIG. 8  is an isometric view of the torch of  FIG. 7  with the handle removed to reveal the interior components; and 
           [0028]      FIG. 9  is a cross-sectional side view of the torch of  FIG. 7  along line  9 - 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The present invention is applicable to a variety of welding implements including, but not limited to, TIG torches, GMAW guns, shielded metal arc welding (SMAW) holders, plasma torches, and the like. The following example embodiments will make reference to TIG welding only for convenience of explanation. The present invention is equally applicable to many other welding-type processes. 
         [0030]    Referring now to  FIG. 1 , a welding system  10  suitable for a number of welding processes, including gas tungsten arc welding (GTAW) and tungsten inert gas (TIG) welding, includes a power supply  12  disposed within an enclosure  14 . The power supply  12  is configured to condition raw power, for example from a transmission power line, into a power suitable for welding. The enclosure  14  is defined by a base  16 , front and back panels  18   a ,  18   b , and a pair of side panels  20   a ,  20   b  attached to the base  16 . A top cover  22  having a handle  24  is secured to the pair of side panels  20   a ,  20   b  to form the enclosure  14 . The front panel  18   a  includes control knobs  26  and outlets and receptacles  28  to facilitate the connection of welding accessories to the power supply  12 . A welding gun output terminal  30  is provided to connect a torch or gun  32  to the power supply  12  via welding cable  34 . The gun  32  is designed to hold a tungsten electrode  35 . To complete a welding circuit, a clamp  38  is provided to connect a workpiece  36  to the power supply  12  via a cable  40  and workpiece output terminal  41 . A gas cylinder  39  is used to store gas that is delivered to the torch  32  during the welding process. 
         [0031]    In addition to the power supply  12 , the enclosure  14  may also house an optional cooling system (not shown) designed to regulate the temperature of the gun  32  and the component internal to the enclosure  14 . In this regard, the optional cooling system is designed to circulate coolant to and from the gun  32  via a coolant conduit or path  42 . 
         [0032]    Referring now to  FIG. 2 , an exploded view of the welding gun  32  of  FIG. 1  is shown. The welding gun  32  includes the tungsten electrode  35  that is configured to be partially surrounded by the nozzle assembly  44 . As will be described, the nozzle assembly  44  may include multiple configurations. A collet body  60  is configured to engage the electrode  35  and pass through a nozzle insulator  62 , a torch body  64 , and backcap insulator  66  to engage a collet  68 . The collet  68 , in turn, engages a backcap  70 . 
         [0033]    The nozzle assembly  44  is formed of multiple components. The nozzle assembly  44  includes a non-conductive nozzle  72  that, for example, may be formed of porcelain or ceramics. The non-conductive nozzle  72  defines a hollow or open inner portion or chamber  73 . In this regard, the non-conductive nozzle  72  may be formed as a cylinder to allow the tungsten electrode  35  to pass therethrough. It is contemplated, however, that the non-conductive nozzle  72  may be formed in other geometrical shapes, such as frusto-conical shape. 
         [0034]    Referring now to  FIG. 3 , a cross-sectional view of a heat pipe  75  is shown. The heat pipe  75  includes a casing  76  and a passageway including a wick  78  and a vapor cavity  80 . For ease of reference, the heat pipe  75  will be described as having a first end  82  and a second end  84 . The heat pipe  75  contains a working fluid that is capable of being in a vapor or a liquid phase. The working fluid may be any one of or a mixture of a number of fluids including, but not limited to, water, helium, mercury, sodium, ammonia, ethanol, and methanol. The working fluid is distributed between a gas phase present in the vapor cavity  80  and a liquid phase present in the wick  78 . The wick  78  is a porous material that lines at least a portion of the casing  76 . The size of the pores may be selected such that the working fluid is “wicked” by capillary action to portions of the wick that do not contain the working fluid. The appropriate pore size may vary depending on the surface tension of the working fluid in liquid phase and the surface energy of the material composing the wick. 
         [0035]    The heat pipe  75  may be placed in an environment in which the heat pipe  75  is exposed to a thermal gradient over the length of the body. As shown by the environment temperature line in  FIG. 3 , the first end  82  is exposed to high temperatures relative to the low temperatures of the second end  84 . In the presence of a thermal gradient across the length of the heat pipe  75 , the heat pipe  75  may extract the energy from the high temperature side and transfer it to the low temperature side according to the thermal cycle described below and generally indicated by the directional arrows in  FIG. 3 . 
         [0036]    First, the working fluid in the first end  82 , which is exposed to the high temperatures, evaporates to form a vapor phase that absorbs the thermal energy from the environment. This vapor phase then migrates along the vapor cavity  80  from the higher temperature first end  82  to the lower temperature second end  84 . Once the vapor phase has reached the lower temperatures of the second end  84 , the vapor in the vapor cavity  80  condenses back into liquid and is absorbed by the wick  78 , releasing thermal energy at the low temperature second end  84 . The working fluid, now in liquid form, is wicked back towards the high temperature first end  82  via capillary action. This heat transfer is continuous and the working fluid contained within the passageway may be evaporating on one end while simultaneously condensing on the other end. 
         [0037]    It should be appreciated that in order for this thermal cycle to be induced, the high temperature end should be at temperatures high enough to cause the working fluid to evaporate. Likewise, the low temperature end should be at temperatures low enough that the working fluid, when in vapor phase, may condense. 
         [0038]    Because the heat pipe  75  is a closed system, the casing  76  is designed to have sufficient mechanical strength at high temperatures and high pressures. A large fraction of the working fluid may be vaporized at high temperatures, essentially turning the heat pipe  75  into a pressure vessel. 
         [0039]    Referring now to  FIGS. 4-6 , in accordance with one configuration of the present invention, the welding gun  32  extends from a distal end  81  to a proximal end  83  and has a torch body  64  including a handle  85  having a plurality of ribs  86 . The torch body may include textured portions  88  for easy gripping. The handle  85  may be composed of a hard rubberized material. As can be seen in  FIG. 6 , the torch body  64  can be slid into the handle  85 , such that a set of ridges  90  on the torch body  64  frictionally hold the torch body  64  in the handle  85 . The end of the handle  85  includes a removable cap  92  made, for example, of a hard plastic or rubber. The set of ridges  90  and the handle  85  form one end of the fluid/gas channel, while the removable cap  92  and handle  85  form the other end of the fluid/gas channel. 
         [0040]    Inside the torch body  64  and handle  85  are a number of internal components including a connector  94 , a heat pipe  96  similar to the heat pipe  75  shown in  FIG. 3 , a thermal energy sink  98 , a cylindrical sleeve  100 , and a torch head  102 . It should be noted that  FIG. 6  is a partial cross-sectional view that does not include a cross section of the heat pipe  96 . However, the internal components of the heat pipe  96  include a wick and casing, such as described above with respect to  FIG. 3 . 
         [0041]    The connector  94  has a port  104  that is adapted for attachment to a cable that supplies power and gas. Radially-extending holes  106  extend from a location inside the connector  94  to a cavity  108  between the handle  85  and the internal components. The connector  94  also has an end that connects to the heat pipe  96 . 
         [0042]    The heat pipe  96  connected to the connector  94  extends the length of the handle  85  to contact the torch head  102 . As the heat pipe  96  extends towards the torch head  102 , a thermal energy sink  98  and the cylindrical sleeve  100  are also attached to the heat pipe  96 . The heat pipe  96  may have a casing made from a solid conductive material such as, for example, aluminum, copper, and the like, such that it may carry the welding current. 
         [0043]    The thermal energy sink  98  may be a separate component that contacts the heat pipe  96  or may be integrally connected to the heat pipe  96 . The thermal energy sink  98  may be composed of a material having high rates of thermal conductivity, such as copper or aluminum, and may have a large surface area, such fins  103  as shown, to increase the amount of heat transferred. There may or may not exist a gap between the thermal energy sink  98  and the handle  85 . 
         [0044]    The cylindrical sleeve  100  has radially-extending holes  110  on the end of the cylindrical sleeve  100  closest to the fins  103  of the thermal energy sink  98 . The radially-extending holes  110  extend from a cavity  111  to an annularly extending channel  112  formed between the cylindrical sleeve  100  and the heat pipe  96 . The annularly extending channel  112  extends from the connection between the heat pipe  96  and the cylindrical sleeve  100  to a location where the heat pipe  96  and cylindrical sleeve  100  attach to the torch head  102 . 
         [0045]    It should be noted that in this configuration, the cavities  108  and  111  are in communication with one another such that a gas can flow from one cavity to another. Thus, the thermal energy sink  98  either has a geometry that permits the communication of the cavities  108  and  111  with one another or has a gap between the thermal energy sink  98  and the handle  85  that permits the communication of the cavities  108  and  111  with one another. 
         [0046]    The torch head  102  has a set of channels  114  that extend from the annularly extending channel  112  to an inner bore  116  of the torch head  102 . At the points where the inner channels  114  intersect the surface of the inner bore  116  are a plurality of holes  118 . 
         [0047]    In operation, a gas and power supply cable  34  is connected to the connector  94 , to supply a gas and current to the torch  32 . The current supplied by the cable  34  is conducted and travels through the connector  94 , through the heat pipe  96 , and to the torch head  102  to supply a current to the electrode  35  of  FIGS. 2 and 3 . As the welding process generates heat at and near the torch head  102 , the heat pipe  96  transfers the thermal energy from the torch head  102  away from the torch head  102  and to the thermal energy sink  98 . At the thermal energy sink  98 , the thermal energy may be dispersed over a large area, such as the fins  103 . In this way, the intense heat generated by the welding process is directed away from the torch head  102  such that the welding process may occur for a longer period of time without the welding components becoming excessively hot. 
         [0048]    Simultaneously, a fluid, such as an inert shielding gas, flows from the cable  34  into the connector  94 . The fluid flows from the connector  94  out of the radially-extending holes  106  into the cavity  108 . The fluid flows past the fins  103  of the thermal energy sink  98  towards the cavity  111 . As the fluid flows past the fins  103  of the thermal energy sink  98 , the fluid convectively transfers the thermal energy away from the thermal energy sink  98 . The fluid then flows from the cavity  111  into the radially-extending holes  110  into the annularly-extending channel  112 . The fluid flows from the annularly-extending channel  112  into the inner channels  114  of the torch head  102  and out of the holes  118 . This flow pattern serves the dual purpose of directing the heat away from the thermal energy sink  98  via convective heat transfer and, in the case where the fluid is a shielding gas, also provides a shielding gas to the welding surface to reduce the formation of oxides during the welding process. Uniquely, the handle  85  both provides a location for gripping the welding implement as well as forms a portion of the channel through which the fluid, such as a shielding gas may flow. As shielding gases must typically be delivered to the site of the weld anyway, it is advantageous that the shielding gas can also be used to transfer the thermal energy transmitted to the heat pipe or thermal energy sink. 
         [0049]    Referring now to  FIGS. 7-9 , another configuration of the welding implement is shown. In this configuration, the welding torch  32  again has a torch body  64  connected to a handle  85 . However, as is shown in  FIG. 9 , the torch body  64  and the handle  85  are each connected to a connecting block  120 , which also acts as part of the thermal energy sink. The other exterior features, such as the removable cap  92  and the plurality of ribs  86  on the handle  85 , are generally present. 
         [0050]      FIGS. 8 and 9 , which illustrate the components inside the torch body  64  and handle  85  show that, as previously described, the connecting block  120  attaches to both the torch body  64  and the handle  85 . However, in this configuration, there are four heat pipes  96  that extend from the outer edges of the torch head  102  back through the connecting block  120  and to the end of the thermal energy sink  98 . 
         [0051]    Again, the connector  94  is adapted for connection to a cable that supplies gas and power. However, in this configuration, there is only a single radially-extending hole  106  extending from a location inside the connector  94  to the cavity  108 . Instead of the connector  94  connecting to a heat pipe, the connector  94  connects to a conductive rod  122 . 
         [0052]    The conductive rod  122  extends from the connector  94  towards the torch head  102 . The thermal energy sink  98  including the fins  103  is located around the conductive rod  122  and may, but does not necessarily, contact the conductive rod. The thermal energy sink  98  may be integrally formed with the connecting block  120 . Again, the thermal energy sink  98  has a geometry, such as including the fins  103 , that allows the cavity  108  to be in communication with the cavity  111 . The cavity  111  is located on the side of the connecting block  120  opposite the torch head  102 . There is a radially-extending hole  110  that extends between the cavity  111  and the channel  124 . The channel  124  leads from an area of connection around the thermal energy sink  98  and the connection point of the conductive rod  122  and the torch body  64  into the torch head  102  and inner bore  116  of the torch head  102 . 
         [0053]    In operation, a gas and power supply cable  34  of  FIGS. 1 and 2  is connected to the connector  94 , to supply a gas and current to the torch  32 . The current supplied by the cable  34  is conducted and travels through the connector  94  to the conductive rod  122  and into the torch head  102 . As this current is conducted through these components, these components generate thermal energy. 
         [0054]    This thermal energy is particularly great at the torch head  102  near the location of the welding. The four heat pipes  96  transfer the thermal energy in the torch head  102  away from the torch head  102 , through the connecting block  120 , and to a location at or around the thermal energy sink  98 . The thermal energy generated by the various components may be directed towards the thermal energy sink  98  through either contact with the conductive rod  122  or contact with the connecting block  120 . 
         [0055]    The gas runs from the connector  94  through the cavity  108 , past the thermal energy sink  98  to the cavity  111 , through the radially-extending hole  110  through the channel  124 , and into the inner bore  116 . As the gas passes the thermal energy sink  98 , the gas transfers the thermal energy of the thermal energy sink  98  convectively out of the welding torch  32 . Additionally, this gas may be an inert shielding gas and protect the welding area from oxidation at high temperatures. In this way, the welding process may occur for a longer period of time with out the welding torch  32  becoming excessively hot and reducing or eliminating the downtime to cool. 
         [0056]    It should be appreciated that, although two configurations were described above, other modifications may be made to the welding implement. For example, a separate hollow channel for carrying the shielding gas may extend from the connecting block  120  towards the torch head  102  and connect directly to the torch head  102  or to a channel near the torch head  102 . In this case, the heat pipe or conductive rod may extend from the connector  94  directly into a portion of the torch head  102 . 
         [0057]    Moreover, it is contemplated that a wide variety of fluids, whether a gas or liquid, could be used to transfer the thermal energy away from the thermal energy sink  98 . For example, the fluid may be a liquid that cycles through portions of the welding implement and, in particular, around the thermal energy sink  98 , to transfer the thermal energy out of the welding implement. Of course, the term fluid is inclusive of the inert shielding gas as described in the above configuration. 
         [0058]    The present invention has been described in terms of the various embodiments, and it should be appreciated that many equivalents, alternatives, variations, and modifications, aside from those expressly stated, are possible and within the scope of the invention. Therefore, the invention should not be limited to a particular described embodiment.