Abstract:
A dispensing gun having a mix head for combining at least two fluid components, with a purge rod slidably positioned within the mix head. The purge rod has a forward position for preventing flow from the component inlets, and a rearward position allowing flow from the component inlets with an actuator for moving the purge rod. The dispensing gun further a lubrication chamber that provides lubricant to the purge rod with the lubricant originating from a lubricant cartridge.

Description:
BACKGROUND 
       [0001]    The present invention relates to plural component dispensing devices, and, more particularly, to the lubrication of a mechanical purge rod in a plural component dispensing gun. 
         [0002]    Typically, plural components of the type relating to the present invention comprise a resin component which is chemically inert in isolated form and an isocyanate material which is also chemically inert in isolated form. When isocyanate and resin are combined, an immediate chemical reaction begins taking place that results in the cross-linking, curing, and solidification of the mixture. Therefore, the two components are routed separately in a dispensing gun up until near the tip, where they are mixed and dispensed out of the tip. Between dispensing shots of mixture, the mixing area and tip of the dispensing gun must be cleared of mixture or else the mixture will solidify and render the dispensing gun inoperable. However, purging the mixing area and tip of the dispensing gun can be difficult due to the high (and increasing) viscosity of the solidifying plural mixture. 
       SUMMARY 
       [0003]    According to one embodiment of the present invention, a dispensing gun has a mix head for combining at least two fluid components, with a purge rod slidably positioned within the mix head. The purge rod has a forward position for preventing flow from component inlets, and a rearward position allowing flow from the component inlets, with an actuator for moving the purge rod. The dispensing gun further includes a lubrication chamber that provides lubricant to the purge rod, with the lubricant originating from a lubricant cartridge. 
         [0004]    In another embodiment, a dispensing gun has a housing and a lubricant cartridge that is insertable into the housing. The dispensing gun further has a lubricant pathway within the housing that is connected to the lubricant cartridge, and a mixing mechanism that is attached to the housing. The mixing mechanism is for mixing at least two fluid components. A purge rod is slidably positioned in the mixing mechanism. A lubricant pathway within the mixing mechanism is connected with the lubricant pathway within the housing, which allows for lubricant to be delivered to the purge rod. 
         [0005]    In another embodiment, a method of operating a dispensing gun includes pressurizing two fluid components and a lubricant cartridge that is attached to the dispensing gun. The method further includes moving a purge rod rearward to allow the two fluid components to flow into and mix in a mixing chamber. Also included is lubricating the purge rod with the pressurized lubricant continually during operation of the dispensing gun, and preventing the lubricant from reaching the mixing chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a side elevation view of a dispensing gun and a lubrication cartridge. 
           [0007]      FIG. 2  is a rear elevation view of the dispensing gun of  FIG. 1  with the lubrication cartridge inserted into the dispensing gun. 
           [0008]      FIG. 3A  is a top cross-section view of a mix head along line  3 - 3  in  FIG. 1 , with a mix head dispensing a plural component mix and a purge rod in a rearward position. 
           [0009]      FIG. 3B  is a top cross-section view of a mix head along line  3 - 3  in  FIG. 1 , with a mix head not dispensing a plural component mix and a purge rod in a forward position. 
           [0010]      FIG. 4  is a side cross-section view of a dispensing gun along line  4 - 4  in  FIG. 2  showing a piston operated lubricant cylinder. 
           [0011]      FIG. 5  is a top cross-section view of a dispensing gun along line  5 - 5  in  FIG. 1  showing a lubricant pathway. 
           [0012]      FIG. 6  is a side cross-section view of a mix head along line  6 - 6  in  FIG. 2  showing a lubricant chamber. 
           [0013]      FIG. 7  is a side cross-section view of an alternate embodiment of the dispensing gun of  FIG. 2  along line  7 - 7  in  FIG. 2  showing a lubricant cartridge disposed in a handle of the dispensing gun. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  is a side elevation view of dispensing gun  10  with cartridge  12 .  FIG. 2  is a rear elevation view of dispensing gun  10 . Shown in  FIGS. 1-2  are dispensing gun  10 , cartridge  12 , cylinder  14 , mix head  16 , tip  18 , purge rod  20 , first component inlet  22 , gas inlet  24 , handle  26 , trigger  28 , control out  30 , control in  32 , viewing window  34 , solenoid  36 , metering system  38 , and second component inlet  40 . The discussion of  FIGS. 1-2  will occur simultaneously. 
         [0015]    Dispensing gun  10  includes cylinder  14 , mix head  16 , and handle  26 . Mix head  16  is mounted to the front end of cylinder  14  and includes tip  18 , purge rod  20 , first component inlet  22 , and second component inlet  40 . First component inlet  22  and second component inlet  40  are connected to mix head  16  near the rear of mix head  16 . Tip  18  is connected to the front of mix head  16 , and purge rod  20  is slidably positioned within mix head  16  and tip  18 . Handle  26  is mounted to the bottom side of cylinder  14 , and includes trigger  28  and control out  30 . Trigger  28  is pivotally connected to handle  26 , and control out  30  is attached to an upper rear portion of handle  26 . 
         [0016]    Cylinder  14  has gas inlet  24 , control in  32 , viewing window  34 , and solenoid  36 . Gas inlet  24  is attached to the rear of cylinder  14 , and viewing window  34  is along the side of cylinder  14 . Solenoid  36  is attached to the bottom side of cylinder  14 , between cylinder  14  and handle  26 . Attached to the rear of solenoid  36  is control in  32 . 
         [0017]    Metering system  38  is fluidly connected to dispensing gun  10  through first component inlet  22 , gas inlet  24 , and second component inlet  40 . Metering system  38  is electrically connected to dispensing gun  10  through control out  30  and control in  32 . 
         [0018]    Dispensing gun  10  operates when a user pulls trigger  28 . An electrical signal is sent through control out  30  to metering system  38 . Metering system  38  then sends the appropriate signal to solenoid  36  through control in  32 . Solenoid  36  controls a pneumatically operated actuation system for dispensing gun  10 . In one embodiment, solenoid  36  delivers gas from metering system  38  to power a gas piston inside cylinder  14 . The gas piston moves purge rod  20  to the rear (to the left as shown in  FIG. 1 ), dispensing plural component mix  42  (as described further with the discussion of  FIG. 3A ). When the trigger is released, solenoid  36  is controlled to reverse the gas piston. This action moves purge rod  20  forward (to the right as shown in  FIG. 1 ), which stops the flow of plural component mix  42 . However, in an alternative embodiment, solenoid  36  is replaced with a mechanical spool valve. Such a spool valve is mechanically controlled by the user pulling or releasing trigger  28 . In such an embodiment, the spool valve controls the pneumatically operated actuation system, including the gas piston. Additionally, due to the mechanical structure in this embodiment, control out  30  and control in  32  are not required. 
         [0019]    The pressurized gas provided by metering system  38  that enters dispensing gun  10  at gas inlet  24  is also used to pressurize cartridge  12 . Pressurization then occurs when cartridge  12  is inserted into cylinder  14 . Cartridge  12  contains lubricant that is forced through cylinder  14  into mix head  16 , where it lubricates purge rod  20 . 
         [0020]    The components and configuration of dispensing gun  10  as shown in  FIGS. 1-2  allow for plural component mix  42  to be dispensed from dispense gun  10 . This occurs in part because cartridge  12  lubricates purge rod  20 . As the lubricant in cartridge  12  is used, the user can see the level of lubricant remaining in cartridge  12  through viewing window  34 . After the lubricant in cartridge  12  is consumed, cartridge  12  can be removed and a new cartridge  12  can be inserted into dispensing gun  10  in order to ensure the lubrication of purge rod  20 . 
         [0021]    One skilled in the art can appreciate that the lubricant can comprise one or more of many different suitable lubricants. In the illustrated embodiment, the lubricant is the TSL™ Throat Seal Lubricant available from Graco Inc., Minneapolis, Minn. However, in alternative embodiments other lubricants can be used. In addition, the outside of cartridge  12  is preferably at least translucent if not transparent. This allows a user to see the amount of lubricant in cartridge  12  through viewing window  34 . 
         [0022]    Shown in  FIGS. 3A-3B  is a top cross-section view of mix head  16  along line  3 - 3  in  FIG. 1 , with mix head  16  dispensing plural component mix  42  in  FIG. 3A  and not dispensing in  FIG. 3B . Shown in  FIGS. 3A-3B  are mix head  16 , tip  18 , purge rod  20 , plural component mix  42 , first component  44 , second component  46 , first orifice  48 , second orifice  50 , bearing sleeve  52 , lubricant chamber  54 , mix module  56 , packing nut  58 , and packing housing  60 . 
         [0023]    In  FIG. 3A , first orifice  48  and second orifice  50  are attached to respective cavities on opposite sides of mix head  16 . First orifice  48  and second orifice  50  are attached and fluidly communicate with first component inlet  22  and second component inlet  40 , respectively (as shown in  FIG. 2 ). Positioned in the interior of mix head  16  and between first orifice  48  and second orifice  50  is mix module  56 . As stated previously, tip  18  is attached to the front of mix head  16 , with bearing sleeve  52  being located inside tip  18 . 
         [0024]    Behind mix module  56  is lubricant chamber  54 . Lubricant chamber  54  is a cavity in mix head  16  containing lubricant that is bounded by mix module  56  in the front and packing housing  60  in the rear. Packing housing  60  is positioned within mix head  16  and is held in place by packing nut  58 , with packing nut  58  being attached inside mix head  16 . Purge rod  20  is slidably positioned inside mix head  16 , specifically within tip  18 , bearing sleeve  52 , mix module  56 , lubricant chamber  54 , packing housing  60  and packing nut  58 . 
         [0025]    Mix head  16  is shown dispensing plural component mix  42 . The dispensing occurs because first component  44  and second component  46  are pressurized by metering system  38  (shown in  FIG. 1 ). First component  44  and second component  46  are transported from metering system  38 , through first component inlet  22  and second component inlet  40 , respectively, and to first orifice  48  and second orifice  50 , respectively. When purge rod  20  is retracted towards the rear of dispensing gun  10 , the pressure forces first component  44  and second component  46  from first orifice  48  and second orifice  50  into mix module  56 , respectively. First component  44  and second component  50  then mix and form plural component mix  42 , which begins to solidify. However, plural component mix  42  is dispensed out of dispensing gun  10  through bearing sleeve  52  and tip  18  prior to solidification. 
         [0026]    In  FIG. 3B , purge rod  20  is shown in a forward position. In this position, purge rod  20  prevents flow of first component  44  and second component  46  from first orifice  48  and second orifice  50 , respectively. In addition, when purge rod  20  was moved forward from the rear (as shown in  FIG. 3A ), purge rod  20  forced out all of first component  44 , second component  46 , and plural component mix  42  that was in mix module  56 , bearing sleeve  52 , and tip  18 . 
         [0027]    The components and configuration of dispensing gun  10  as shown in  FIG. 3  allow for first component  44  and second component  46  to mix and form plural component mix  42 , which is dispensed out of tip  18 . In addition to stopping the flow of first component  44  and second component  46 , the forward motion of purge rod  20  purges dispensing gun  10  of solidifying plural component mix  42 . This prevents dispensing gun  10  from being clogged by hardened plural component mix  42 . As will be discussed further with  FIGS. 4-7 , lubrication is provided from cartridge  12  to lubricant chamber  54  to aid the sliding motion of purge rod  20 . 
         [0028]    Shown in  FIG. 4  is a side cross-section view of dispensing gun  10  along line  4 - 4  in  FIG. 2 . Shown in  FIG. 4  are cartridge  12 , cylinder  14 , gas inlet  24 , cartridge bay  62 , cartridge knob  64 , rear cartridge seal  66 , cartridge piston  68 , cartridge piston hooks  69 A- 69 B, cartridge piston seals  70 A- 70 B, front cartridge seals  72 A- 72 B, cartridge ring  73 , cartridge end seal  74 , cartridge vent  76 , piercer  78 , and cartridge bay seal  80 . 
         [0029]    Cartridge  12  has cartridge knob  64  attached at one end. Also near that end, rear cartridge seal  66  is positioned on the exterior of cartridge  12 , cartridge piston  68  is slidably positioned in the interior of cartridge  12 , and cartridge vent  76  is an aperture through the wall of cartridge  12 . Around cartridge piston  68  are cartridge piston seals  70 A- 70 B, at the front of cartridge piston  68  are cartridge piston hooks  69 A- 69 B, and in front of cartridge piston  68  is lubricant. Positioned at the opposite end of cartridge  12  are front cartridge seals  72 A- 72 B and cartridge ring  73 . Attached to the very end of cartridge  12  is cartridge end seal  74 . 
         [0030]    In  FIG. 4 , cartridge  12  is inserted into cylinder  14 , specifically into a cavity in cylinder  14  identified as cartridge bay  62 . Attached to cylinder  14  at the front end of cartridge bay  62  is piercer  78 . When cartridge  12  is inserted into cartridge bay  62 , piercer  78  breaks through cartridge end seal  74 . In the illustrated embodiment, cartridge end seal  74  is comprised of a metal foil affixed to the end of cartridge  12 . 
         [0031]    In the illustrated embodiment, cartridge knob  64  has lobes that extend perpendicular from the center axis of cartridge  12 . There are corresponding cuts in cylinder  14  that allow the lobes to pass into cartridge bay  62 . After cartridge  12  is inserted all the way into cartridge bay  62 , the user can turn cartridge  12  90 degrees. Thereby, the lobes on cartridge knob  64  prevent cartridge  12  from being withdrawn from cartridge bay  62 . This is because cylinder  14  does not have corresponding cuts to allow the lobes to exit cartridge bay  62  when cartridge  12  is in the ¼ turned orientation. 
         [0032]    Pressurized gas from metering system  38  (as shown in  FIG. 1 ) is directed through gas inlet  24  and into cartridge bay  62 . Specifically, the gas is introduced between rear cartridge seal  66  and cartridge bay seal  80 , cartridge bay seal  80  being positioned in cartridge bay  62  forward from cartridge vent  76 . This allows the gas to enter cartridge  12  behind cartridge piston  68 , forcing cartridge piston  68  forward. Because piercer  78  penetrated cartridge end seal  74 , lubricant is forced into the front end of cartridge bay  62 . However, front cartridge seals  72 A- 72 B prevent the flow of lubricant to the rear of cartridge bay  62 . 
         [0033]    As the lubricant is consumed, the pressurized gas will drive cartridge piston  68  forward. When cartridge piston  68  is sufficiently forward, cartridge piston hooks  69 A- 69 B will be bent towards each other in order to pass through cartridge ring  73 . However, once the forward ends of cartridge piston hooks  69 A- 69 B are past cartridge ring  73 , cartridge piston hooks  69 A- 69 B will expand back to their original configuration. In this configuration, cartridge piston  68  is locked forward and can no longer retract. 
         [0034]    The components and configuration of dispensing gun  10  as shown in  FIG. 4  allow for a sealed cartridge  12  to be attached to cylinder  14 . Specifically, cartridge  12  is substantially fully enclosed and contained within cylinder  14 . From this position, cartridge  12  is opened and pressurized to allow the flow of lubricant into cylinder  14 . Due to the pressurized piston design, dispensing gun  10  can operate while being held at any angle and in any orientation. In addition, the forward locking feature of cartridge piston  68  prevents cartridge piston  68  from being withdrawn, which prevents air, plural component mix  42 , or other non-lubricant material from being drawn in to lubricant chamber  54 , cylinder pathway  82  (as shown later in  FIG. 5 ), or mix head pathway (as shown later in  FIG. 6 ). 
         [0035]    Depicted in  FIG. 4  is one embodiment of the present invention, to which there are alternative embodiments. For example, cartridge  12  could be held in cartridge bay  62  using a latch or other mechanism, such as threads wherein cylinder bay  62  is tapped with threads. 
         [0036]    Shown in  FIG. 5  is a top cross-section view of dispensing gun  10  along line  5 - 5  in  FIG. 1 . Shown in  FIG. 5  are cylinder  14 , mix head  16 , cartridge bay  62 , piercer  78 , and cylinder pathway  82 . Cylinder pathway  82  is a lubricant channel within cylinder  14 . In the illustrated embodiment, cylinder pathway  82  extends straight between cartridge bay  62  and mix head  16 . Cylinder pathway  82  allows pressurized lubricant from the end of cartridge bay  62  to reach mix head  16 . 
         [0037]    Depicted in  FIG. 5  is one embodiment of the present invention, to which there are alternative embodiments. For example, cylinder pathway  82  can extend in other orientations and can have multiple segments. Such embodiments allow cylinder pathway  82  to be routed around the other components in cylinder  14 , such as the pneumatic system, including solenoid  36 . 
         [0038]    Shown in  FIG. 6  is a side cross-section view of mix head  16  along line  6 - 6  in  FIG. 2 . Shown in  FIG. 6  are cylinder  14 , mix head  16 , tip  18 , purge rod  20 , bearing sleeve  52 , lubricant chamber  54 , mix module  56 , packing nut  58 , packing housing  60 , cylinder pathway  82 , mix head pathway  84 , check valve assembly  86 , check valve seat  88 , check valve ball  90 , check valve spring  92 , bleed port  94 , bleed port screw  96 , gas piston rod  98 , and u-cup seal  100 . 
         [0039]    Mix head  16  is attached to and inset into cylinder  14 . Cylinder pathway  82  comes up from the lower rear of mix head  16 . Cylinder pathway  82  is then routed around at least one side of the rear of mix head  16  to an area near the upper side of the rear of mix head  16 . 
         [0040]    The parts and connections of mix head  16  are as described with  FIGS. 3A-3B , with some additional features shown in  FIG. 6 . For example, mix head pathway  84  is fluidly connected to cylinder pathway  82 . Connected to the rear end of mix head pathway  84  is check valve assembly  86 . Check valve assembly  86  has check valve seat  88 , check valve ball  90 , and check valve spring  92 . Check valve seat  88  is attached to mix head  16 , and the front end of check valve spring  92  resting on a counterbore shelf in mix head pathway  84 . Check valve ball  90  is positioned between check valve seat  88  and check valve spring  92 . In addition, bleed port  94  is fluidly connected to mix head pathway  84 . However, bleed port screw  96  is normally attached to mix head  16 , and normally prevents lubricant flow through bleed port  94 . Also fluidly connected to mix head pathway  84  is lubricant chamber  54 . 
         [0041]    As stated previously, purge rod  20  is slidably positioned in mix head  16 . The rear end of purge rod  20  is connected to gas piston rod  98 . As discussed with  FIG. 1 , there is a gas piston inside cylinder  14  that moves purge rod  20  by way of gas piston rod  98 . Also near the rear end of purge rod  20  is u-cup seal  100 . U-cup seal  100  is positioned between packing nut  58  and packing housing  60 . 
         [0042]    When cartridge  12  is pressurized (as discussed with  FIG. 4 ), lubricant can travel from cylinder pathway  82  into mix head pathway  84 . From there the lubricant can travel through check valve assembly  86  because the pressure forces check valve ball  90  off of check valve seat  88 . This allows the lubricant to flow around check valve ball  90  and eventually into lubricant chamber  54 . 
         [0043]    In order to drain the air or other fluid that may be in cylinder pathway  82  or mix head pathway  84 , bleed port screw  96  can be removed to let the fluid drain as the lubricant is progressing through cylinder pathway  82  and mix head pathway  84 . Once the lubricant is in lubricant chamber  54 , it bathes purge rod  20  and lubricates purge rod  20  as it slides back and forth within mix head  16 . Lubricant is substantially sealed in lubricant chamber  54  and is substantially prevented from leaking rearward by u-cup seal  100 . Lubricant is also substantially prevented from leaking forward into mix module  56 , bearing sleeve  52 , and tip  18  by the close fit of purge rod  20  in mix module  56 . However, minute amounts of lubricant can be consumed by leakage, but more lubricant will be provided from cartridge  12  as needed. 
         [0044]    The components and configuration of dispensing gun  10  as shown in  FIG. 6  allow for lubricant to reach purge rod  20 . However, check valve assembly  86  ensures that there will be no reverse flow in mix head pathway  84 . The lubrication of purge rod  20  assists in the sliding of purge rod  20 , which allows for the initiation and cessation of plural component mix  42  dispensing. In addition, lubrication chamber  54  is substantially sealed as to substantially prevent the leakage and loss of the lubricant. 
         [0045]    Shown in  FIG. 7  is a side cross-section view of an alternate embodiment handle  26  along line  7 - 7  in  FIG. 2 . Shown in  FIG. 7  are cartridge  12 , handle  26 , cartridge bay  62 , and piercer  78 . In the illustrated embodiment, cartridge bay  62  and piercer  78  are located in handle  26 , which means that cartridge  12  is inserted in handle  12 . However, these components function in the same manner as those described in  FIG. 4 . In such an embodiment, handle  12  has a pathway (not shown) that serves as a lubricant channel that is fluidly connected with cylinder pathway  82 , such that lubricant can still reach mix head  16  (as shown in  FIG. 6 ). Thereby, this alternate embodiment dispensing gun  10  operates in the same manner as the embodiment described in  FIGS. 1-6 . 
         [0046]    It should be recognized that the present invention provides numerous benefits and advantages. For example lubrication of purge rod  20  is particularly helpful because of the high viscosities of first component  44 , second component  46 , and plural component mix  42 . It is also advantageous due to the fact that plural component mix  42  is solidifying as it is being dispensed. For another example, cartridge  12  is attached to dispensing gun  10 , which eliminates another fluid connection to metering system  38 , and makes the lubrication system self contained. For a further example, cartridge  12  is easily replaceable and externally visible so that dispensing gun  10  can be quickly replenished with lubricant to ensure continuous lubrication of purge rod  20 . 
         [0047]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.