Patent Publication Number: US-7582844-B2

Title: Torch handle gas control

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 10/083,101, titled “Torch Handle Gas Control,” filed Feb. 26, 2002 now U.S. Pat. No. 6,689,983. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to plasma arc torches and more particularly to devices and methods for controlling the flow of a working gas to a plasma arc torch. 
     BACKGROUND OF THE INVENTION 
     Plasma arc torches are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of ionized gas particles toward a workpiece. The plasma arc torch is typically connected to a power supply that provides both gas and electric power for operation of the plasma arc torch and is operable through a trigger disposed within a torch handle for activation of the gas and the electric power. With plasma arc torches of the known art, the trigger operates both the gas and the electric power such that neither the gas nor the electric power are controlled separately local to the torch handle. Some known art plasma arc torches provide separate gas controls, however, the controls are disposed within the power supply or at a location remote from the operator. 
     Activation of gas flow only, i.e. no electric power, is often advantageous in certain applications such as for cooling torch parts or the workpiece. However, many plasma arc devices do not provide for a gas only mode of operation, and those that do provide for such a mode require the operator to initiate and terminate the gas flow at the power supply, or at another remote location, not local to the plasma arc torch where operations are being performed. As a result, operation of a gas only mode is relatively time consuming and cumbersome in plasma arc torch systems of the known art. 
     Additionally, with plasma arc torches of the known art, a few seconds typically elapse from the time an operator engages a trigger to when a plasma stream is generated, which is a function of the amount of time required for the gas to travel from the power supply, through the torch lead, and to the torch head. Accordingly, with longer torch leads, the restart times are correspondingly longer, which results in further delays that reduce work efficiency and that can become frustrating to an operator if the torch is shut off and re-ignited on a regular basis. In one known system, a gas control valve is provided that dissipates gas in a plasma arc chamber after a plasma arc has been extinguished. However, the gas must still travel the length of a torch lead and rise gradually in accordance with the teachings of the known system. 
     Accordingly, a need remains in the art for a device and method that more efficiently controls the flow of gas to a plasma arc torch. A further need exists for such a device and associated method that reduces restart times, that is relatively simple to operate, and that does not require significant manual dexterity of the operator. 
     SUMMARY OF THE INVENTION 
     In one preferred form, the present invention provides a plasma arc torch that comprises a torch handle, a torch head disposed within the torch handle, a torch lead operable with the torch head, a gas control device disposed within the torch handle and operable with the torch lead and the torch head, and an activation member operable with the gas control device. Accordingly, the activation member activates the gas control device such that gas flow is supplied from the torch lead to the torch head, and the activation member deactivates the gas control device such that the gas flow is terminated local to the torch handle. Several forms of the activation member are provided, which may comprise a trigger system, a button, or a safety member, among others. Similarly, several forms of the gas control device are provided, which may comprise a gas control valve or a switch that activates a separate gas control device disposed within a power supply, among others. In another form, a gas control device is provided local to the torch handle so that gas at operating pressure is available adjacent the torch head such that restart times are reduced. 
     Additionally, methods of operating the plasma arc torch to provide a supply of gas local to the torch handle are provided by the present invention. The methods generally comprise operating the gas control device disposed within a handle of a plasma arc torch through an activation member as previously set forth to activate the supply of gas to the plasma arc torch and further to terminate, or deactivate, the supply of gas. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a manually operated plasma arc apparatus constructed in accordance with the principles of the present invention; 
         FIG. 2  is a side view of a plasma arc torch comprising a gas control device with an activation member, with one half of the handle removed to show the details of construction, in accordance with the principles of the present invention; 
         FIG. 3  is a cross-sectional view of a plasma arc torch comprising a gas control valve with a trigger system and constructed in accordance with the principles of the present invention; 
         FIG. 4  is a side view of a plasma arc torch comprising a switch that activates a gas control device, with one half of the handle removed to show the details of construction, in accordance with the principles of the present invention; 
         FIG. 5  is a side view of a plasma arc torch comprising a gas control device that is activated by a button, with one half of the handle removed to show the details of construction, in accordance with the principles of the present invention; and 
         FIG. 6  is a side view of a plasma arc torch comprising a gas control device that is activated by a safety member, with one half of the handle removed to show the details of construction, in accordance with the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring to the drawings, a torch handle gas control according to the present invention is generally operable with a manually operated plasma arc apparatus as indicated by reference numeral  10  in  FIG. 1 . Typically, the manually operated plasma arc apparatus  10  comprises a plasma arc torch  12  connected to a power supply  14  through a torch lead  16 , which may be available in a variety of lengths according to a specific application. Further, the power supply  14  provides both gas and electric power, which flow through the torch lead  16 , for operation of the plasma arc torch  12  as described in greater detail below. 
     As used herein, a plasma arc apparatus, whether operated manually or automated, should be construed by those skilled in the art to be an apparatus that generates or uses plasma for cutting, welding, spraying, gouging, or marking operations, among others. Accordingly, the specific reference to plasma arc cutting torches, plasma arc torches, or manually operated plasma arc torches herein should not be construed as limiting the scope of the present invention. Furthermore, the specific reference to providing gas to a plasma arc torch should not be construed as limiting the scope of the present invention, such that other fluids, e.g. liquids, may also be provided to the plasma arc torch in accordance with the teachings of the present invention. 
     Referring to  FIG. 2 , a plasma arc torch according to the present invention is illustrated and generally indicated by reference numeral  20 . As shown, the plasma arc torch  20  comprises a gas control device  22  that is operable with a torch head  24  and a torch lead  26  within a torch handle  28 . The gas control device  22  is illustrated as being disposed within the torch handle  28 , however, the term “disposed within” should be construed as meaning located proximate the torch handle  28  such that an operator can operate the gas control device  22  without moving to a remote location. Furthermore, the torch lead  26  is operable with the torch head  24  as shown, wherein a supply of gas and electric power is provided from the torch lead  26  to the torch head  24  for operation of the plasma arc torch  20 . 
     Generally, the gas control device  22  operates to activate or deactivate the supply of gas from the power supply (not shown) as required during use by an operator. As further shown, the plasma arc torch  20  also comprises an activation member  30 , (also referred to as a control  30 ), which activates the gas control device  22  to supply the flow of gas and further deactivates the gas control device  22  to terminate the flow of gas to the torch head  24 . As described in greater detail below, the gas control device may comprise a gas control valve, or a switch local within the torch handle  28  that activates another gas control device disposed within the power supply, among others. Additionally, the activation member may comprise a trigger system, a button, a safety member, or a pneumatic source, each of which is described in detail below. Accordingly, a plasma arc torch with gas control local to the torch handle  28  is provided in accordance with the principles of the present invention, and the specific embodiments illustrated and described herein for the gas control devices and the activation members should not be construed as limiting the scope of the present invention. Rather, other gas control devices and activation members known in the art may be employed local to the torch handle  28  while remaining within the scope of the present invention. 
     Referring now to  FIG. 3 , the preferred form of the present invention comprises a gas control valve  40  as the gas control device and a trigger system  42  as the activation member. Operation of the trigger system  42  is further described in copending application titled “Plasma Arc Torch Trigger System,” filed on Feb. 26, 2002, which is commonly assigned with the present application and the contents of which are incorporated herein by reference. As shown, the trigger system  42  comprises a selector  44  disposed within a housing  46 , wherein the selector  44  is operable to different operating positions, one of which comprises a first operating position that operates the plasma arc torch  20  is a first operating mode to deliver gas only to the plasma arc torch  20 . To operate the plasma arc torch  20  in the first operating mode, the selector  44  is moved forward in the direction of arrow A so that a post  48  clears a stop  50 , and the housing  46  may be pivoted upward in the direction of arrow B. As the housing  46  is pivoted upward, the housing  46  engages a plunger  52 , which activates the gas control valve  40  to an “on” position, which allows a supply of gas to flow from the torch lead  26  through the gas control valve  40  and to the torch head  24 . As the housing  46  is released, the plunger  52  moves downward, thereby deactivating the gas control valve  40  and terminating gas flow to the torch head  20 . Accordingly, gas control local to the torch handle  28  is provided in accordance with the teachings of the present invention. 
     Additionally, the gas control device  22 , whether a gas control valve  40  or other, maintains operational pressure adjacent the torch head  24 , which reduces restart time of the plasma arc torch  20 . Accordingly, the plasma arc  20  is operable in another embodiment with the gas control device  22  and a conventional trigger, without an activation member  30 , such that the plasma arc torch  20  provides reduced restart times over torches without an independent gas control local to the torch handle  28 . 
     Further, the gas control device  22  is preferably connected to the torch head  24  and the torch lead  26  using a quick disconnect  56  as shown and described in copending application titled “Modular Plasma Arc Torch,” filed on Feb. 26, 2002, which is commonly assigned with the present application and the contents of which are incorporated herein by reference. Accordingly, the gas control  22  may be quickly assembled to and disassembled from the torch components such as the torch head  24  and the torch lead  26  within the plasma arc torch  20  as necessary. 
     As shown in  FIG. 4 , the gas control device may alternately comprise a switch  60  that is activated by the activation member  30  (illustrated as the trigger system  42 ). With the trigger system  42  as the activation member  30 , the housing  46  is pivoted upward and an engagement member  62  depresses an arm  64  of the switch  60 , thereby activating the switch  60 . The switch  60  then activates another gas control device (not shown), for example a solenoid, which can be located within the power supply, and the supply of gas is provided through the torch lead  26  and the torch head  24 . Alternately, the activation member  30  may be a button  66  (shown dashed) that engages the engagement member  62 , or which directly engages the arm  64  of the switch  60 . Preferably, the button  66  is resiliently biased such that the switch  60  is off when the button  66  is not depressed. Further, although the button  66  is shown positioned within the trigger system  42 , the button may also be positioned in other locations proximate the torch handle  28  and remain within the scope of the present invention. Moreover, although gas pressure is not built up local to the torch head  24  as with previous embodiments, the switch  60  maintains independent gas control local to the torch handle  28 . 
     Referring now to  FIG. 5 , the plasma arc torch  20  is illustrated with a button  70  that activates the gas control device  22 . As shown, the button  70  is disposed within a trigger  72 , however, the button  70  may alternately be disposed in other locations proximate, or local, the torch handle  28  and remain within the scope of the present invention. To activate the gas control device  22 , which may be a gas control valve or a switch as previously described, among others, the button  70  is depressed, which causes the button  70  to activate the gas control device  22  either directly or through a separate engagement member. Accordingly, the button  70  is depressed to activate the supply of gas. Conversely, to terminate the supply of gas, the button  70  is released. Furthermore, the button  70  is preferably resiliently biased such that the gas control device  22  is off when the button  66  is not depressed. 
     With reference to  FIG. 6 , the activation member may alternately comprise a safety member  80 , such as that disclosed in U.S. Pat. No. 5,597,497, which in incorporated herein by reference. In operation, the safety member  80  is moved upward in the direction of arrow C, which causes the safety member  80 , or a separate engagement member, to engage the gas control device  22 , (which may be the valve or switch as previously described, among others), which activates the supply of gas. To terminate the supply of gas, the safety member  80  is released. Accordingly, gas supply local to the torch handle  28  is controlled with the safety member  80  as shown. 
     Accordingly, gas control local to a torch handle of a plasma arc torch is provided by the teachings of the present invention. The gas control is accomplished through a gas control device, which may be a gas control valve or a switch that activates a separate gas control device disposed within a power supply, among others. Additionally, the gas control device is activated by an activation member, which may comprise a trigger system, a button, a safety member, or a pneumatic source, among others. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the substance of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.