Spray gun with paint cartridge

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's handle portion to its spray nozzle.

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'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's proximal end is actuated.

Several methods of loading the cartridge into the spray gun may be employed. In one method the spray gun'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'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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A cartridge20for a spray gun is shown inFIG. 1. The cartridge20has a tubular body22and whose front end has a conical nozzle24with a concentric aperture26. Paint may be delivered into the cartridge20through a paint supply aperture52, which is located relatively far from the front end of the tubular body22. The cartridge20also has a rear end28with an aperture30for allowing a needle valve member40to slidably pass therethrough. A spring32in the cartridge20biases the needle valve member40forward to press the pointed leading end36thereof into the front aperture26, blocking it to prevent paint from escaping the tubular body22. The needle valve member40has a knob44at the rear end28for connection to a trigger62on the spray gun60for adjusting the position of the needle valve member40in the tubular body22of the cartridge20. Applicant'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 gun60is hereby incorporated by reference.

As illustrated inFIG. 2, a cartridge20is shown loaded in a spray gun60. The spray gun60has a trigger62which engages the needle valve member40to adjust the flow of paint available to be sprayed by the spray gun60. In the embodiment shown, the trigger62has a cradle46which the needle40rests in. When the trigger62is moved aft ward, cradle46engages knob44on the rear end of the needle valve member40and pulls the needle rearward against the force of the spring32to open the front aperture26allowing paint to flow out therefrom. The spray gun60also has a spray limit adjustment stop64having a knob66for screwing the adjustment stop to a desired position for contacting the rear of knob44on needle40and limiting the size of the opening of the needle valve member40relative to the front aperture26.

FIGS. 2 and 3show a hinged embodiment of a breach loading spray gun60in accordance with the present invention. The spray gun60has a front portion74, a hinge75and a rear portion76attached to the front portion by the hinge75. A cartridge20can be inserted into the chamber68until the shoulder34of the cartridge engages the seat70in the front portion74of the spray gun60. When the hinge75is operated to close and latch the front portion74to the rear portion76, the cartridge is pushed forward in the chamber68by the rear portion76such that shoulder34is pushed forward until there is a positive stop at seat70which creates an air-tight seal between the cartridge20and the seat70, as shown in the embodiment inFIG. 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 seal43as inFIG. 2. The latch, as shown inFIG. 2, comprises a fixed portion77and a movable portion78which can move up or down to engage or disengage from the fixed portion.

When the spray head assembly90on front portion74of the spray gun60is in place, and the needle valve member40is moved by trigger62, air entrained past the front aperture26of cartridge20allows for paint to spray from the spray head assembly. The air supply to the spray head assembly90is supplied as in any spray gun. For example, it may have air channels which must align, as in air channel94in the front portion74of the spray gun, to fluidly connect with air channel92in the rear portion of the spray gun76. The air channels92,94may have a close tolerance fit or have seals or have a tube connecting the air channels92,94. The air is supplied to the handle72through an air hose95. The air flow control valve knob96(as shown inFIG. 3) controls the volume of air delivered to the spray head assembly90to control the spray pattern.

Alternatively the air hose95may enter the front portion74of the spray gun so no air channel connections need be made from the front portion74to the rear portion76.

In an alternative embodiment, as shown inFIG. 4, a spray gun has a cartridge20having an annular indented portion47on tubular body22for engaging a pin45which is put in place to lock the cartridge20into spray gun60, a collar49activated by trigger62is then placed on the back of needle valve member40adjacent knob44to adjust the position of needle40and thus regulate the paint flow in the spray gun.

The embodiment shown inFIG. 4has a reservoir of paint54attached to the cartridge20. 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 aperture52are also possible including the use of a hose running to a paint supply. The embodiment ofFIG. 4has air channels92,94similar to the embodiment ofFIG. 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 portion74inFIG. 2may have threads for screwing onto threads on the rear portion76. In this manner the cartridge may be inserted in the spray gun60by unscrewing the front portion from the rear portion, inserting the cartridge and then screwing on the front portion74.

In other embodiments, the front portion74may be attached to the rear portion76by 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 cartridge20pushed forward into place by a plunger having a handle to push on the plunger and secure the cartridge20in the barrel. The cartridge20is 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 trigger62to the needle valve member40such as pins or collars. Moreover, the spring32need not be contained within the cartridge but may be external thereto acting between the end cap28and a protuberance on the externally projecting needle shaft.

Referring toFIG. 5, there is shown a paint cartridge100that incorporates a gasket or seal element102. More particularly, the cartridge100comprises a tubular body portion104having a proximal end106, a front end108and that at least partially contains a spring biased needle valve member110. The front end108of the needle valve has a taper112(FIG. 9) designed to cooperate with a nozzle outlet114(FIG. 6) at the front end108of the paint cartridge104. That is to say, the needle valve member110can be made to selectively open or close the nozzle outlet114when actuated by a trigger mechanism as earlier described in connection with the discussion ofFIG. 4.

The cartridge100further includes a liquid inlet port116in fluid communication with a lumen of the tubular cartridge body portion104. 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 connector118.

The cartridge100of the embodiment ofFIG. 5has an annular shoulder120where a larger diameter portion122of the cartridge100integrally joins to a more nearer portion124to the front end108of a lesser diameter. Adjacent this shoulder120is a first gasket or sealing surface126and the radially projecting gasket102. The gasket102includes at least one aperture, and preferably two, at128and130(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 cartridge100is molded. If not integrally molded with the cartridge body104, the gasket members102and126can be formed as a separate piece and placed on the smaller diameter portion124and with the gasket126against the surface of the shoulder120with a friction fit or may be adhesively or otherwise bonded in place.

FIG. 7illustrates with a perspective view a replaceable cartridge having a slightly different configuration from that shown inFIG. 5. InFIG. 7, the cartridge body132again has a nozzle outlet134that 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 cartridge132is an annular gasket136from which is supported a radially extending gasket member138. Formed through the thickness dimension of the gasket member138are apertures140and142. Again, the material used in forming the gasket may be either flexible or rigid. Furthermore, the gasket member138may be integrally formed with the annular gasket136or the two may be formed separately and joined using a suitable bonding technique known to those skilled in the art. Otherwise the annular gasket136may be plugged on the cartridge body132or may slide on the cartridge body132It is also contemplated that the annular gasket136may be fixed on the cartridge body132in an injection molding operation.

The perspective view ofFIG. 8differs only slightly from the embodiment ofFIG. 7in that there are molded in surrounding relation to the apertures140and142tubular bushings144and146that project in a frontal direction from the gasket member138. The tubular bushings144and146may also be mailed to project in the direction of the proximal end (not shown) of the cartridge body132. 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 bushings144,146may be integrally molded with the gasket member138and, as before, the annular seal or gasket136may be integrally molded onto the tubular cartridge body132or, alternatively, may be assembled as a separate piece onto the cartridge body132and then adhesively bonded at a desired predetermined location along the length dimension of the cartridge body.

In the embodiments ofFIGS. 7 and 8the gasket member138is of a somewhat rectangular shape. This is recommendable because there are two apertures140and142and respectively two tubular bushings144,146are 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 ofFIGS. 5-8, consideration will next be given to their application in as a replaceable cartridge for a spray gun.

Referring toFIG. 9, there is shown a partial cross-sectional view of a spray gun in which the cartridge ofFIG. 5or7is adapted to be used.

InFIG. 9, the spray gun's air cap is identified by numeral148and is seen to include an annular air passageway having air exit ports at150that direct an airstream to air jets exiting the ports152on the face of the air cap148. The air cap148fulfills a function similar to the spray head90of the embodiments showed inFIG. 2. The air cap148is removably secured to the barrel portion154of the spray gun by means of a retainer nut156. This also serves to retain an air distribution ring158awithin the barrel portion154of the spray gun assembly. The air distribution of the spray gun is realized by a first air distribution element158and an air distribution ring158a, which has a central opening and fitted into this central opening is the replaceable cartridge100containing the spring loaded needle valve40(seeFIG. 4, for example). A segment of the handle or rear portion of the gun is identified by numeral160inFIG. 9and is pivotally joined to the front or barrel portion154by a hinge pin162. As has been explained in conjunction with the views ofFIGS. 2 and 3, the hinge connection allows the front or barrel portion154to assume an open condition relative to the handle portion160allowing the cartridge100to be inserted into the assembly. The gasket member102on the cartridge100is designed to be located at the interface between the barrel portion154and the handle portion160when the two are in their closed relationship with respect to one another while the apertures128and130are aligned with the air passage164in the handle portion and the air passage166in the barrel portion to thereby seal the joint therebetween at the interface between the separable halves of the spray gun.

The annular gasket or seal126on the cartridge100ofFIG. 5becomes captured between the shoulder120on the cartridge100inFIG. 9and the wall surrounding the proximal end of the air distribution ring158aso that when the front or barrel portion154of the gun is latched closed with respect to the handle portion160, the annular seal126serves to limit any air escape at that interface. Thus, a tight sealing between the cartridge100and the air distribution elements158and158aof the spray gun is realized.

In the event the gasket arrangement shown inFIG. 8is employed, the barrel portion154is provided with a bore (not shown inFIG. 9) that surrounds the air passage166to thereby accommodate the bushings144and146therein. The bushings144and146not only serve to conduct the air jet supply lines164,166across 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 assembly90(FIG. 2) or148(FIG. 9) is positioned adjacent the cartridge aperture26(FIG. 1) or114(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 cartridge100having a tube116for 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.