Abstract:
A spray paint gun having a disposable cartridge inserted therein such that paint can flow through the cartridge in the spray gun without touching the spray gun. Since no part of the spray gun has paint touching it, there is no cleaning of the spray gun or its components. The cartridges can be easily inserted into the spray gun and easily removed such that different color paints can be used in the spray gun in quick succession without down time for cleaning. There is no use of solvents for cleaning, making the cartridge spray gun environmentally friendly. The disposable cartridges eliminate expensive time consuming cleaning. The cartridges can be breach loaded into the front portion of a spray gun and front portion containing the cartridge can quickly snapped into place and ready for use by a hinged connection to the rear portion or by other connection means. The cartridge may include an integrally formed or otherwise attached gasket member to perfect an airtight seal at a joint in the air passage leading from the gun&#39;s handle portion to its spray nozzle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of application Ser. No. 12/178,229, filed Jul. 23, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to liquid spray guns and more particularly to spray guns having easy to install replaceable cartridges for delivery of paint without the paint contacting the spray gun. 
     2. Description of the Related Art 
     In a typical spray gun, the interior components of the spray gun must be disassembled for proper cleaning and then reassembled for use. This is time consuming and also creates hazardous waste and disposal costs. Along with these inconveniences, unnecessary exposure to toxic vapors and solvents occurs during cleaning. 
     It is desirable to be able to quickly and easily change the colors used in paint spray guns without having to clean the spray gun each time a different color is used. 
     It is desired to have a spray gun with a disposable cartridge that shields the gun itself from exposure to paint such that no clean up is required. It is also desirable to eliminate the use of cleaners, such as solvents, with the associated waste which needs to be disposed of. 
     The cartridge should be easy to use and be quickly insertable and removable from the spray gun body. A spray gun to accommodate such cartridges, that allows quick and easy connections of the pin in the cartridge to the spray gun trigger and to block air flow bypass around the cartridge is also desired. 
     SUMMARY OF THE INVENTION 
     The spray gun uses a paint cartridge consisting of a tube with a front conic portion to engage a needle valve member for controlling the paint flow through the cartridge, a rear end having the needle&#39;s proximal end extending therefrom and a connection to a paint source to allow paint to flow through the cartridge when a trigger coupled to the needle&#39;s proximal end is actuated. 
     Several methods of loading the cartridge into the spray gun may be employed. In one method the spray gun&#39;s cartridge receiving chamber is split and is hinged to allow quick and easy access to insert or remove the cartridge by breach loading the front portion of the hinged spray gun and then locking the cartridge in place when the hinged front portion is made to latch with the rear portion. 
     In a second method, the cartridge is inserted into the rear of the spray gun and locked in place. 
     In yet another method, the front and rear portions of the spray gun can be disconnected and then fastened together after a cartridge is installed. 
     Another method would be a chamber in the spray gun having an aperture for inserting the cartridge and then locking the cartridge in place. 
     In a split and hinged gun construction, pressurized air for creating the spray condition is applied to the handle portion of the gun and made to flow through a first passage terminating at the location where the spray gun is designed to align with the first passage when the gun&#39;s front and rear portions are closed and latched relative to one another. To prevent air leakage at the joint between the two air passages, the replaceable cartridge may be designed to incorporation a gasket appendage that provides a seal at the joint between the two air passages. 
     By being able to quickly insert a cartridge, the color of the paint being sprayed can be changed without having to clean the spray gun. Further, the spray gun does not have to be cleaned after each use since no paint contacts the spray gun, thus saving cleaning materials and time while eliminating disposal of the cleaning materials and excess paint. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to eliminate the need to clean a spray gun after each use. 
     It is an object of the invention to eliminate the need for cleaning fluids, cleaning brushes and wipes in readying a spray gun for a next use. 
     It is an object of the invention to be able to quickly change colors of paint when using the spray gun. 
     It is an object of the invention to save on clean up time and the costs associated with it. 
     It is an object of the invention to reduce waste of paint. 
     It is an object of the invention to reduce down time attributable to clean up and maintenance of spray guns. 
     Other objects, advantages and novel features of the present invention will become apparent from the following description of the preferred embodiments when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cross sectional view of a paint cartridge; 
         FIG. 2  is a side cross sectional view of a cartridge installed in a hinged spray gun in the closed position; 
         FIG. 3  is a side cross sectional view of a cartridge installed in a hinged spray gun in the open position; 
         FIG. 4  is a side cross sectional view of a cartridge installed in a rear loading spray gun; 
         FIG. 5  is a side view of a cartridge for use in the spray gun of  FIGS. 2 and 3  and incorporating a gasket; 
         FIG. 6  is a front view of the cartridge of  FIG. 5 ; 
         FIG. 7  is a perspective view of an alternative embodiment of a cartridge having a gasket seal; 
         FIG. 8  is a perspective view of the further alternative embodiment of a cartridge having a gasket seal; and 
         FIG. 9  is a partial longitudinal cross-section view taken through the spray gun with the cartridge of  FIG. 5  or  7  installed therein. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A cartridge  20  for a spray gun is shown in  FIG. 1 . The cartridge  20  has a tubular body  22  and whose front end has a conical nozzle  24  with a concentric aperture  26 . Paint may be delivered into the cartridge  20  through a paint supply aperture  52 , which is located relatively far from the front end of the tubular body  22 . The cartridge  20  also has a rear end  28  with an aperture  30  for allowing a needle valve member  40  to slidably pass therethrough. A spring  32  in the cartridge  20  biases the needle valve member  40  forward to press the pointed leading end  36  thereof into the front aperture  26 , blocking it to prevent paint from escaping the tubular body  22 . The needle valve member  40  has a knob  44  at the rear end  28  for connection to a trigger  62  on the spray gun  60  for adjusting the position of the needle valve member  40  in the tubular body  22  of the cartridge  20 . Applicant&#39;s patent application Ser. No. 11/540,747 entitled Disposable Spray Gun Cartridge and filed Sep. 30, 2006 showing a cartridge as may be used in spray gun  60  is hereby incorporated by reference. 
     As illustrated in  FIG. 2 , a cartridge  20  is shown loaded in a spray gun  60 . The spray gun  60  has a trigger  62  which engages the needle valve member  40  to adjust the flow of paint available to be sprayed by the spray gun  60 . In the embodiment shown, the trigger  62  has a cradle  46  which the needle  40  rests in. When the trigger  62  is moved aft ward, cradle  46  engages knob  44  on the rear end of the needle valve member  40  and pulls the needle rearward against the force of the spring  32  to open the front aperture  26  allowing paint to flow out therefrom. The spray gun  60  also has a spray limit adjustment stop  64  having a knob  66  for screwing the adjustment stop to a desired position for contacting the rear of knob  44  on needle  40  and limiting the size of the opening of the needle valve member  40  relative to the front aperture  26 . 
       FIGS. 2 and 3  show a hinged embodiment of a breach loading spray gun  60  in accordance with the present invention. The spray gun  60  has a front portion  74 , a hinge  75  and a rear portion  76  attached to the front portion by the hinge  75 . A cartridge  20  can be inserted into the chamber  68  until the shoulder  34  of the cartridge engages the seat  70  in the front portion  74  of the spray gun  60 . When the hinge  75  is operated to close and latch the front portion  74  to the rear portion  76 , the cartridge is pushed forward in the chamber  68  by the rear portion  76  such that shoulder  34  is pushed forward until there is a positive stop at seat  70  which creates an air-tight seal between the cartridge  20  and the seat  70 , as shown in the embodiment in  FIG. 4 . Other means for sealing the air inside the spray gun are possible including a tight fit of the cartridge in the cartridge chamber or a seal such as a ring seal  43  as in  FIG. 2 . The latch, as shown in  FIG. 2 , comprises a fixed portion  77  and a movable portion  78  which can move up or down to engage or disengage from the fixed portion. 
     When the spray head assembly  90  on front portion  74  of the spray gun  60  is in place, and the needle valve member  40  is moved by trigger  62 , air entrained past the front aperture  26  of cartridge  20  allows for paint to spray from the spray head assembly. The air supply to the spray head assembly  90  is supplied as in any spray gun. For example, it may have air channels which must align, as in air channel  94  in the front portion  74  of the spray gun, to fluidly connect with air channel  92  in the rear portion of the spray gun  76 . The air channels  92 ,  94  may have a close tolerance fit or have seals or have a tube connecting the air channels  92 ,  94 . The air is supplied to the handle  72  through an air hose  95 . The air flow control valve knob  96  (as shown in  FIG. 3 ) controls the volume of air delivered to the spray head assembly  90  to control the spray pattern. 
     Alternatively the air hose  95  may enter the front portion  74  of the spray gun so no air channel connections need be made from the front portion  74  to the rear portion  76 . 
     In an alternative embodiment, as shown in  FIG. 4 , a spray gun has a cartridge  20  having an annular indented portion  47  on tubular body  22  for engaging a pin  45  which is put in place to lock the cartridge  20  into spray gun  60 , a collar  49  activated by trigger  62  is then placed on the back of needle valve member  40  adjacent knob  44  to adjust the position of needle  40  and thus regulate the paint flow in the spray gun. 
     The embodiment shown in  FIG. 4  has a reservoir of paint  54  attached to the cartridge  20 . The cartridge may have the reservoir screwed on or the reservoir may be integral with the cartridge or may be in any other way connected to the spray gun. Other means of feeding paint to the cartridge through the paint supply aperture  52  are also possible including the use of a hose running to a paint supply. The embodiment of  FIG. 4  has air channels  92 ,  94  similar to the embodiment of  FIG. 2 . 
     The various figures show different embodiments of spray guns with different positions of controls and different features to show that many designs for spray guns may be used with the replaceable cartridges of the present invention. Further, many different customized cartridge designs may be used with different commercially available spray guns. 
     In an alternative embodiment, not shown, the front portion  74  in  FIG. 2  may have threads for screwing onto threads on the rear portion  76 . In this manner the cartridge may be inserted in the spray gun  60  by unscrewing the front portion from the rear portion, inserting the cartridge and then screwing on the front portion  74 . 
     In other embodiments, the front portion  74  may be attached to the rear portion  76  by latches, bayonet attachments, snaps, screws or other fasteners which may be of many different types. 
     In a further embodiment, not shown, a chamber inside of a spray gun barrel can be accessed through an opening in the top of the barrel and a cartridge  20  pushed forward into place by a plunger having a handle to push on the plunger and secure the cartridge  20  in the barrel. The cartridge  20  is therefore pushed forward into the chamber much like a bolt action rifle with the plunger acting like the bolt. The needle is then connected to the trigger. 
     There may be many means of attaching the trigger  62  to the needle valve member  40  such as pins or collars. Moreover, the spring  32  need not be contained within the cartridge but may be external thereto acting between the end cap  28  and a protuberance on the externally projecting needle shaft. 
     Referring to  FIG. 5 , there is shown a paint cartridge  100  that incorporates a gasket or seal element  102 . More particularly, the cartridge  100  comprises a tubular body portion  104  having a proximal end  106 , a front end  108  and that at least partially contains a spring biased needle valve member  110 . The front end  108  of the needle valve has a taper  112  ( FIG. 9 ) designed to cooperate with a nozzle outlet  114  ( FIG. 6 ) at the front end  108  of the paint cartridge  104 . That is to say, the needle valve member  110  can be made to selectively open or close the nozzle outlet  114  when actuated by a trigger mechanism as earlier described in connection with the discussion of  FIG. 4 . 
     The cartridge  100  further includes a liquid inlet port  116  in fluid communication with a lumen of the tubular cartridge body portion  104 . The port permits a liquid to be sprayed to enter the lumen of the cartridge and may be connected to a liquid supply canister or other tube source of the liquid via a connector  118 . 
     The cartridge  100  of the embodiment of  FIG. 5  has an annular shoulder  120  where a larger diameter portion  122  of the cartridge  100  integrally joins to a more nearer portion  124  to the front end  108  of a lesser diameter. Adjacent this shoulder  120  is a first gasket or sealing surface  126  and the radially projecting gasket  102 . The gasket  102  includes at least one aperture, and preferably two, at  128  and  130  ( FIG. 6 ) that extend through the thickness dimension thereof. It may be formed from an elastomeric material so as to be slightly compressible, but also could be of the same rigid plastic material from which the body of the cartridge  100  is molded. If not integrally molded with the cartridge body  104 , the gasket members  102  and  126  can be formed as a separate piece and placed on the smaller diameter portion  124  and with the gasket  126  against the surface of the shoulder  120  with a friction fit or may be adhesively or otherwise bonded in place. 
       FIG. 7  illustrates with a perspective view a replaceable cartridge having a slightly different configuration from that shown in  FIG. 5 . In  FIG. 7 , the cartridge body  132  again has a nozzle outlet  134  that can be selectively totally or partially occluded by a spring-loaded needle valve as in the earlier described embodiments. Circumferentially mounted at a predetermined location along the length of the cartridge  132  is an annular gasket  136  from which is supported a radially extending gasket member  138 . Formed through the thickness dimension of the gasket member  138  are apertures  140  and  142 . Again, the material used in forming the gasket may be either flexible or rigid. Furthermore, the gasket member  138  may be integrally formed with the annular gasket  136  or the two may be formed separately and joined using a suitable bonding technique known to those skilled in the art. Otherwise the annular gasket  136  may be plugged on the cartridge body  132  or may slide on the cartridge body  132  It is also contemplated that the annular gasket  136  may be fixed on the cartridge body  132  in an injection molding operation. 
     The perspective view of  FIG. 8  differs only slightly from the embodiment of  FIG. 7  in that there are molded in surrounding relation to the apertures  140  and  142  tubular bushings  144  and  146  that project in a frontal direction from the gasket member  138 . The tubular bushings  144  and  146  may also be mailed to project in the direction of the proximal end (not shown) of the cartridge body  132 . But the first variant is more recommendable because usually the mounting of a cartridge is arranged into the head portion of a spray gun. The tubular bushings  144 ,  146  may be integrally molded with the gasket member  138  and, as before, the annular seal or gasket  136  may be integrally molded onto the tubular cartridge body  132  or, alternatively, may be assembled as a separate piece onto the cartridge body  132  and then adhesively bonded at a desired predetermined location along the length dimension of the cartridge body. 
     In the embodiments of  FIGS. 7 and 8  the gasket member  138  is of a somewhat rectangular shape. This is recommendable because there are two apertures  140  and  142  and respectively two tubular bushings  144 ,  146  are present in parallel arrangement. Of course other shapes of gasket member are possible, particularly if only one aperture or bushing would be present or if more then one aperture or bushing are present in a non-parallel arrangement. 
     Having described the alternative cartridge embodiments of  FIGS. 5-8 , consideration will next be given to their application in as a replaceable cartridge for a spray gun. 
     Referring to  FIG. 9 , there is shown a partial cross-sectional view of a spray gun in which the cartridge of  FIG. 5  or  7  is adapted to be used. 
     In  FIG. 9 , the spray gun&#39;s air cap is identified by numeral  148  and is seen to include an annular air passageway having air exit ports at  150  that direct an airstream to air jets exiting the ports  152  on the face of the air cap  148 . The air cap  148  fulfills a function similar to the spray head  90  of the embodiments showed in  FIG. 2 . The air cap  148  is removably secured to the barrel portion  154  of the spray gun by means of a retainer nut  156 . This also serves to retain an air distribution ring  158   a  within the barrel portion  154  of the spray gun assembly. The air distribution of the spray gun is realized by a first air distribution element  158  and an air distribution ring  158   a , which has a central opening and fitted into this central opening is the replaceable cartridge  100  containing the spring loaded needle valve  40  (see  FIG. 4 , for example). A segment of the handle or rear portion of the gun is identified by numeral  160  in  FIG. 9  and is pivotally joined to the front or barrel portion  154  by a hinge pin  162 . As has been explained in conjunction with the views of  FIGS. 2 and 3 , the hinge connection allows the front or barrel portion  154  to assume an open condition relative to the handle portion  160  allowing the cartridge  100  to be inserted into the assembly. The gasket member  102  on the cartridge  100  is designed to be located at the interface between the barrel portion  154  and the handle portion  160  when the two are in their closed relationship with respect to one another while the apertures  128  and  130  are aligned with the air passage  164  in the handle portion and the air passage  166  in the barrel portion to thereby seal the joint therebetween at the interface between the separable halves of the spray gun. 
     The annular gasket or seal  126  on the cartridge  100  of  FIG. 5  becomes captured between the shoulder  120  on the cartridge  100  in  FIG. 9  and the wall surrounding the proximal end of the air distribution ring  158   a  so that when the front or barrel portion  154  of the gun is latched closed with respect to the handle portion  160 , the annular seal  126  serves to limit any air escape at that interface. Thus, a tight sealing between the cartridge  100  and the air distribution elements  158  and  158   a  of the spray gun is realized. 
     In the event the gasket arrangement shown in  FIG. 8  is employed, the barrel portion  154  is provided with a bore (not shown in  FIG. 9 ) that surrounds the air passage  166  to thereby accommodate the bushings  144  and  146  therein. The bushings  144  and  146  not only serve to conduct the air jet supply lines  164 ,  166  across the interface and thus be positioning elements but may be used as a throttle member in high volume, low pressure (HVLP) spray guns, for example. 
     Any type of air flow passages through the spray gun or to the nose of the spray gun may be used so long as the spray head assembly  90  ( FIG. 2 ) or  148  ( FIG. 9 ) is positioned adjacent the cartridge aperture  26  ( FIG. 1 ) or  114  ( FIG. 6 ) to allow paint to be entrained in the air flow such that the spray gun functions properly in adjustment of the spray pattern. 
     The cartridge  100  having a tube  116  for the paint supply connection may have a threaded connection to a paint reservoir or an integral connection to a paint reservoir or be connected by any other means to a source of paint such as by a hose from a paint can or a paint pump. 
     Although the above has been described with paint as the fluid delivered by the spray gun, any substance used in spray guns may be delivered by the cartridge. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.