Abstract:
An apparatus that dispenses material stored in a soft packet. The apparatus includes a barrel sized to contain the soft packet. The barrel has a front end and a back end. The apparatus also includes a cap removably engaged to the front end of the barrel. The cap has an orifice through which the material may flow. The cap also has inner dimensions sized to form a seal with a top portion of the soft packet to minimize any extraneous air trapped therebetween. The apparatus further includes a plunger positioned within the barrel. The plunger applies pressure to the soft packet when the plunger moves from the back end of the barrel toward the front end of the barrel to force the material out from the packet and through the orifice.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an applicator of viscous and non-viscous material, and more particularly to a dispensing gun for applying sealants and adhesives. 
     2. Background Information 
     In the field of aircraft production and maintenance, adhesives and sealants are continuously being applied to aircraft components. Sealants are used on many of the components of an aircraft to insure that the aircraft&#39;s cabin maintains a near-standard air pressure, even at elevations as high as 60,000 feet. Sealants are also used to prevent fuel leakage from wing tanks on an aircraft. 
     To apply different sealant products, some form of application technology is required when producing an aircraft. For many years, applicator guns were used in the aerospace industry. An applicator gun  300 , as shown in FIG. 1, uses a solid plastic tube  301  made of low-density polyethylene for holding a sealant. Each tube  301  includes a plunger surface  302 , a casing  304 , and a disposable cap  306 . The applicator gun  300  has a metal holder  310  for holding the tube  301  against a pressure-applying assembly  314 . The applicator gun  300  also has a knob  308  coupled with the pressure-applying trigger  309  on the assembly  314 . 
     To load the tube  301  into the applicator gun  300 , an operator unscrews the knob  308  and disengages the pressure applying assembly  314 . The tube  301  is loaded into the metal holder  310  and the assembly  314  is reattached to the metal tube  310 . The cap  306  on the tube  301  is removed and discarded to allow egress of the sealant contained in the tube  301 . The nozzle  311  is attached to aid in flow control. The sealant is applied by squeezing the trigger  309 , causing the assembly  314  to pressure up with compressed air against the back of the plunger surface  302 , moving it forward. The movement of the plunger surface  302  forces the sealant out of the nozzle  311 . Removal of the spent tube  301  is accomplished in the same manner as its installation, only in reverse. 
     Unfortunately, the sealant applicator gun  300  uses disposable cartridges, which are made of hard plastic material. As such, they are not easily compressible, and generate large amounts of hazardous waste, which must be disposed of at high cost. Further, the present method of using hard plastic tubes decreases productivity because of the extensive amount of time necessary to both fill the tubes and then manually swap them once one has been emptied. Finally, the size of the hard tube is not easily varied, and each tube is relatively expensive to produce. Consequently, there is a need in the art for an inexpensive and rapid device for applying sealant, which produces a minimal amount of hazardous waste. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment, an apparatus is used to dispense material stored in a soft packet. The apparatus includes a barrel sized to contain the soft packet, the barrel having a front end and a back end, and a cap removably engaged to the front end of the barrel. The cap has an orifice through which the material may flow, and has inner dimensions sized to form a seal with a top portion of the soft packet to minimize any extraneous air trapped therebetween. The apparatus also has a plunger positioned within the barrel. The plunger applies pressure to the soft packet when it moves from the back end of the barrel toward the front end of the barrel to force the material out from the packet and through the orifice. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be further described with reference to the accompanying drawings wherein like referenced numerals refer to like parts in the several views, and wherein: 
     FIG. 1 is an exploded view of a prior art sealant gun; 
     FIG. 2 is an exploded view of an applicator for dispensing a soft packet of material according to a first embodiment of the present invention; 
     FIG. 3A is a side view of a locking cap of the applicator according to the first embodiment; 
     FIG. 3B is a top view of the locking cap of the applicator according to the first embodiment; 
     FIG. 4 is a partial cross-sectional view of the cap and a forward portion of the applicator according to the first embodiment; 
     FIGS. 5A and 5B are cross-sectional views of the locking cap at a first and second angle, respectively, of the applicator according to the first embodiment; 
     FIG. 6 is a top view of the barrel according to the first embodiment; 
     FIG. 7 is a cross-sectional view of the applicator according to the first embodiment; 
     FIG. 8 is a perspective view of the applicator for dispensing the soft packet of sealant, as used in the first embodiment of the present invention; 
     FIG. 9 is a cross-sectional view of a locking cap of an applicator for dispensing a soft packet of material according to a second embodiment of the present invention; 
     FIG. 10 is a cross-sectional view of the applicator according to the second embodiment; 
     FIG. 11 is a partial cross-sectional view of the cap and a forward portion of the applicator according to the second embodiment; 
     FIG. 12 is a cross-sectional view of a locking cap of an applicator for dispensing a soft packet of material according to a third embodiment of the present invention; 
     FIG. 13 is a cross-sectional view of the cap and a forward portion of the applicator according to the third embodiment; and 
     FIG. 14 is a side view of an applicator including a locking ring according to a fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to an applicator  20  for dispensing either viscous or nonviscous materials stored in a soft packet  32 , as shown in FIG.  2 . The applicator  20  reduces waste by replacing bulky, expensive hard plastic containment tubes with the soft packets  32 , otherwise known as “Chub packs.” The soft packets can easily be varied in size, typically ranging from two to six ounces. The soft packets  32  can be replaced at least six times faster than the prior art hard plastic containers. Further, the use of soft packets allows either the viscous or non-viscous materials to be flash frozen, allowing the materials to be stored for long periods of time. The either viscous or non-viscous materials include, but are not limited to, sealants, lubricants, adhesives, and potting compounds. 
     In a first embodiment, the applicator  20  includes a cap  22 , a barrel  24 , a pressurizing valve assembly  26 , a nozzle tip  28 , and a plunger  30  used in conjunction to apply the material that is held in the soft packet  32  to a desired location. 
     The cap  22  of the applicator  20 , as shown in FIGS. 3A and 3B, includes nine ribs  34   a - 34   i , spaced in three groups of three ribs each, around the cap  22 . The ribs  34   a - 34   i  are positioned to assist an operator in gripping the cap  22  when attempting to attach or disengage the cap  22  from the barrel  24 . As further shown in FIGS. 3A and 3B, the cap  22  also has an end-of-nozzle lip  36  that provides structural support for the end portion of the cap  22  which tends to receive a large amount of pressure when engaged to the nozzle tip  28 . The cap  22  and barrel  24  are preferably made of acetocopolymer M90, made by CELCON®. The M90 was chosen since it was found that most sealants do not stick to it. 
     As shown in FIG. 4, the nozzle tip  28  is attached to the cap  22  by a threading nozzle threads  37  of the nozzle tip  28  into a threaded interior  40  of the cap  22 . Preferably, the nozzle tip  28  comes in various sizes allowing control over the diameter of the bead of the material applied to a surface. The nozzle tip  28  also allows the operator some degree of control over the flow rate of the material. Of course, each size of the nozzle tips  28  preferably has the same diameter nozzle threads  37  to engage the threaded interior  40  of the cap  22 . 
     As shown in FIG. 4, the threaded interior  40  includes a flat edge  42 . The flat edge  42  is located at the end of the threaded interior  40 , and allows removal of cured material, such as residual sealant, from the end of the cap  22 . By removing the end of the nozzle tip  28 , the operator can pull on the residue sealant. The lack of threading causes a break to occur at the flat edge  42  and the residual sealant can be pulled away from the threaded interior  40 . 
     The cap  22 , as shown in FIGS. 4,  5 A, and  5 B, also includes a dagger  44  used to puncture the soft packet  32  and allow the material to flow towards the nozzle tip  28 . The dagger  44  is positioned to prevent the soft packet  32  from clogging the flow path of the material. The cap  22  has a narrowing neck  39  which is slightly smaller in diameter than the packet  32 . The shape of the neck  39  creates and maintains a tight seal between the packet  32  and the cap  22 . The seal between cap  22  and the packet  32  has the function of controlling the sealant so it does not leak back into the barrel  24  of the applicator  20 . 
     As shown in FIGS. 5A,  5 B, and  6 , the bottom of the cap  22  has a first, second, and third ramping tongue  38   a - 38   c , respectively, each spaced 120° about the cap&#39;s centerline. The tongues  38   a - 38   c  are used for precisely locating the cap  22  on the barrel  24 . The tongues  38   a - 38   c  lock the cap  22  onto the barrel  24 , shown in FIGS. 5A and 7, when they respectively engage the cap  22  to three self-locking grooves  52   a - 52   c  of the barrel  24 . The three self-locking grooves  52   a - 52   c  are provided in a thin lip  55  above the tapered edge  50 , as shown in FIGS. 4 and 6. The grooves  52   a - 52   c  provide an audible and visual check to inform the operator that the threads are fully engaged. The tongues  38   a - 38   c , shown in FIG. 3A, at the bottom edge of the cap  22 , drop down into the grooves  52   a - 52   c  and are aligned with the center of the respective grooves  52   a - 52   c . The alignment of the tongues  38   a - 38   c  with the respective grooves  52   a - 52   c  provides a visual indication that cap  22  is fully aligned. Once the cap  22  no longer twists onto the barrel  24 , indents  38   a - 38   c  should be centered in the grooves  52   a - 52   c  of the barrel  24 . 
     The barrel  24  has bayonet mounting tabs  53   a - 53   c , shown in FIG. 6, which retain the cap  22  onto the barrel  24 . The mounting tabs  53   a - 53   c  overlappingly engage with respective cap tabs  41   a - 41   c , shown in FIGS. 5A and 5B, as the cap  22  is turned to align the tongues  38   a - 38   c  with the respective grooves  52   a - 52   c.    
     As shown In FIGS. 4 and 6, the tapered edge  50  has eight vent holes  46   a - 46   h  therein to provide airflow between the inside of the barrel  24  and the outside of the barrel  24 . The vent holes  46   a - 46   h  relieve trapped air between the soft packet  32  and the interior of the barrel  24  when the applicator  20  is being used. The vent holes  46   a - 46   h  also eliminate the chance that air will pass out of the nozzle tip  28  along with the material and interfere with its application onto a surface. The vent holes  46   a - 46   h  are positioned so that it is difficult for the operator to inadvertently cover the holes  46   a - 46   h  and stop the outward flow of air. 
     The tapered edge  50  containing the vent holes  46   a - 46   h  reinforces the holes and assists in the support, handling and use of the applicator  20 . The tapered edge  50  further reduces the sharp edges associated with the end of the barrel  24 , and prevents operator contact with the edge of the cap  22 . The tapered edge  50  also reduces the chance of the viscous fluid dripping onto the outside of the barrel  24 . 
     As shown in FIG. 7, the barrel  24  has ribbing  48  on its outside surface. The ribbing  48  provides additional structural support to keep the barrel  24  from expanding in diameter when pressurized with air. The ribbing  48  is also ergonomic in shape and contour and serves as a comfortable hand-holding surface. 
     FIGS. 2 and 7 show the pressurizing valve assembly  26 . Two lugs  54   a  and  54   b  extend from the barrel  24 , and are hooked to the assembly  26  via hooks  72   a  and  72   b . A knob  76  on the assembly  26 , as shown in FIGS. 2 and 7, tightens and loosens the hooks  72   a  and  72   b . When the knob  76  is turned clockwise, the two hooks  72   a  and  72   b  are drawn in and engage the lugs  54   a  and  54   b , respectively, pulling the barrel  24  up against the valve assembly  26 . This action creates an airtight seal between the barrel  24  and the valve assembly  26 . Applicator lever  66  controls the flow of pressurized air between a pressurized air source  68  and an inside portion  73  of the barrel  24 , between the back of the barrel  24  and the plunger  30 . 
     The plunger  30 , shown in FIGS. 2 and 7, is designed to create a perfect seal with the inside of the barrel  24 . The plunger  30  has a scraping edge  58  with notches  61 , which provide flexibility while the plunger  30  moves within the barrel  24 . The scrapping edge  58  moves the soft packet  32  up along the side wall of the barrel  24 . The plunger  30  also has a tapered side wall  60 , which tapers in circumference from a bottom edge  63  to the scraping edge  58 . The tapered side wall  60  imparts flexibility and reduces side wall drag. A top cavity  62  of the plunger  30  is designed to conform to the inside of the contours of the cap  22 , including the dagger  44 , as shown in FIG.  4 . The hemispherical shape of the top of plunger  30  is such that it fits into the top of the cap  20 , eliminating waste in the spent soft packet  32 . In other words, the conformity of the plunger  30  to the contoured top cavity  62  forces out most of the material in the soft packet  32  when the plunger  30  is fully extended into the barrel  24 . The contoured cavity  62  also allows room for two clips,  71   a  and  71   b , shown in FIG. 2, which seal the ends of the soft packet  32 . 
     Air pressure is partially regulated by the vent holes  33   a-g  within the plunger  30  and a valve  31 , which is attached to the plunger  30  via a nipple  35  at one end, as shown in FIG.  2 . The valve  31  is preferably made of RTV Silicon. The vent holes  33   a - 33   g  are used to vent the pressure behind the plunger  30  so that it does not move while the cap  22  is not attached and the soft packet is not loaded into the barrel  24 . The nipple  35  is shaped with a dull point on it for easy insertion into the bottom of the plunger  30  during assembly. The top of the valve  31  has a recess in it to allow for the clip  71   a  or  71   b  to reside within. The valve  31  acts to relieve pressure behind the plunger  32  when the operator depresses the air valve trigger handle  66 . 
     Once the soft package  32  is inserted into the barrel  24  and the cap  22  is attached, the air pressure behind the plunger  30  moves the plunger  30  which applies force against the soft packet  32 . The force behind the plunger  30  and the pressure that is applied against the soft packet  32  is adequate to seal the eight vent holes  33   a - 33   h . The valve  31  is shaped with a conical section that seats against the eight vent holes  33   a - 33   g  on the top of the plunger  30 . There is a raised edge around each vent hole  33   a - 33   g  on the plunger  30  to impart additional sealing of the valve  31  and plunger  30 . 
     After the soft packet  32  is completely empty and the cap  22  is removed, the plunger  30  will be located at its final position and incapable of moving further due to the lip  56 . The operator may remove the spent soft packet  32  by depressing the air valve trigger  66 , allowing a momentary blast of air to fill the barrel  24  and escape out both the barrel vent holes  46   a - 46   h  and out through the plunger vent holes  33   a - 33   g , due to the flexible valve  31 , which in turn causes the spent soft packet  32  to pop out of the end of the barrel  24  and into a disposal unit. 
     When operating the applicator  20 , it is loaded by removing the cap  22  and forcing the plunger  30  down into the barrel  24 . Then, the soft packet  32 , filled with a material such as sealant, is inserted into the barrel  24  and the packet  32  is rammed down into the barrel  24  until it bottoms out against the valve assembly  26 . The cap  22  is then attached by turning it on the bayonet tabs  53   a - 53   c  of the barrel  24  with approximately one third of a turn clockwise until the ramping tongues  38   a - 38   c  lock into the respective self-locking grooves  52   a - 52   c  on the barrel  24 . The threads  37  of the nozzle tip  28 , preferably a SEMCO™ nozzle, are threaded into the threaded interior  40  on top of the cap  22  and used for applying the sealant at a specific location on the component  99  to be sealed. 
     Once the applicator  20  is loaded, and the pressurizing valve assembly has been attached as described above, the lever  66  on the valve assembly  26  is depressed by hand. Triggering the lever  66  causes air pressure to fill the barrel  24  behind the plunger  30 , which moves the soft packet  32  toward the top of the barrel  24 , striking the cap  22 . Within the cap  22 , the soft packet  32  hits the dagger  44 . The film-like soft packet  32  breaks and tears on the dagger  44 . As the soft packet  32  continues to move forward, the end of it seats at the top of the cap  22 . A seal is formed between the soft packet  32  and the cap  22  at the top on a sealing edge  39 . Material begins to flow out of the top of the soft package where dagger  44  is located. As the material flows, as shown in FIG. 8, the plunger  30  moves up the barrel  24 , collapsing the soft packet  32 . As the soft packet  32  collapses, air will tend to build up around the annulus of the soft packet  32  and the barrel  24 . The air escapes through the eight vent holes  46   a - 46   h  located on the tapered ring  50  of the barrel  24 . After the soft packet  32  is completely empty, the plunger  30  stops at the cap  22 . Once the back of the plunger  30  moves past the eight vent holes  46   a - 46   h  and stops on the lip  56  on the barrel  24 , compressed air will flow out the eight vent holes  46   a - 46   h  if the applicator lever  66  continues to be pressed, eliminating any further pressure on the soft packet  32 . 
     Once the soft packet  32  is empty, the cap  22  is removed and set down. The spent soft packet  32  will be visibly sticking out of the top of the barrel  24 . The operator then removes the spent casing by rolling the soft packet  32  off the plunger  30  and discarding it in a waste container, or uses air pressure as described above. 
     The soft packet applicator  20  is cleaned by letting the material, such as sealant, set on the applicator  20 . Once set, the residue is pealed off the outside of the barrel  24 . The cap  22  is cleaned by removing the nozzle tip  28  and pulling out the remaining sealant tail and then carefully scraping the residue from inside the cap  22 . 
     In a second embodiment, the applicator  20  is identical to the first embodiment, with the exception that a daggerless cap  100 , as shown in FIGS. 9,  10 , and  11 , is used with a cavity-free plunger  102  when the applicator  20  applies highly viscous materials that would not adequately flow through the daggered cap design. The cavity-free plunger  102  is identical to the plunger  32  of the first embodiment, except that the top cavity  62  is replaced by an engaging orifice  104  used to engage a shaped rubber stop  106 . The rubber stop  106  is shaped to maximize the pressure applied to the packet  32  to effectively force the viscous fluid out from nozzle tip  28 . The shape of the cavity free plunger  102  and the rubber stop  106  are sized to conform to the top of the cap  22 . 
     In a third embodiment, the applicator  20  is identical to the first embodiment, with the exception that a double dagger cap  110 , as shown in FIGS. 12 and 13, is used with the plunger  30  to apply a material. The double daggers  112   a  and  112   b  break and tear the packet  32  simultaneously, spreading open the holes in the packet  32  wide enough until the film of which the packet  32  is made tears between the two holes. The packet  32  then seats against a domed top  114  of the cap  110 , creating a seal between the packet  32  and the cap  110 . A plunger  116 , which is sized to receive the daggers  112   a  and  112   b  and conform to the cap  22 , applies pressure to the packet  32 . The material flows at the tear between the two daggers  112   a  and  112   b . Since the product flows in the path of least resistance, it flows down through the daggers  112   a  and  112   b  and out the nozzle  28 . Preferably, the two daggers  112   a  and  112   b  have sharp points that are recessed below the edge of the cap  110  providing a margin of safety when handling the cap  110 . 
     In a fourth embodiment, the applicator  20  is identical to the first embodiment and further includes a stop ring  122 , as shown in FIG.  14 . The stop ring  122  may also be used to supplement the second and third embodiments. 
     The ring  122  provides an edge for an internal stop, causing the plunger  30  to stay within the barrel  24 , even under conditions of accidental pressurization. The ring  122  has a flat edge on the outer lip, providing a smooth surface and eliminating any possibility of the operator being cut while re-loading the applicator  20  with a new soft packet  32 . 
     In summary, the applicator  20  of the present invention allows the use of the soft packets  32 , which contain a material, such as but not limited to a sealant, lubricant, adhesive, or potting compound, that must be applied to a surface. The soft packets  32  allow long-term storage of the material, and can be quickly replaced once spent. Further, the soft packet applicator  20  produces only small amounts of waste. Finally, the arrangement of the plunger and dagger of the first and third embodiments of the applicator  20  and the cap and plunger of the second embodiment allow the operator to extract all the material within the soft packet  32  without clogging the exiting pathway of the fluid. 
     It will be apparent to those skilled in the art that many changes can be made in the embodiments described above without departing from the scope of the present invention. Thus, the scope of the present invention should not be limited to the structures and methods described in this application, but only by the structures and methods described by the language of the following claims and the equivalents thereof.