US3417923A - Spray gun for applying a two-component mixture - Google Patents

Description

Dec. 24, 1968 R. CARLSON 3,417,923

SPRAY GUN FOR APPLYING A TWO-COMPONENT MIXTURE Filed Nov. 4, 1966 2 Sheets-Sheet 1 fllZ-I-e-E INVENTOR.

Pom/41.0 5. 61421.50

Dec. 24, 1968 c soN 3,417,923

SPRAY GUN FOR APPLYING A TWO-COMPONENT MIXTURE Filed Nov. 4, 1966 2 Sheets-Sheet 2 INVENTOIH. Pam/.0 5-. 64M 50M United States Patent 3,417,923 SPRAY GUN FOR APPLYING A TWO- COMPONENT MIXTURE Ronald E. Carlson, P.O. Box 708, Hobart, Okla. 73651 Filed Nov. 4, 1966, Ser. No. 592,222 11 Claims. (Cl. 239-112) ABSTRACT OF THE DISCLOSURE A spray gun having two basic parts constituted by a mixing head and a handle portion which is quick detachably secured to the mixing head during the use of the gun. The handle portion carries valving positioned in a plurality of fluid conduits extending through the handle portion, and communicating with fluid conduits in the mixing head. A trigger mechanism is provided on the handle portion which permits the valving to be operated. The mixing head portion of the gun includes a motor, a central body which is connected to the motor, and a spray h ad secured to the central body on the opposite side thereof from the motor. Inside the central body is a mixing chamber in which the several components of the fluid mixture are brought together and intimately mixed. A mixing shaft is drivingly connected to the motor and extends into the mixing chamber formed in the central body of the mixing head.

This invention relates to fluid dispensing devices in general, and more specifically, to a spray gun constructed for the internal mixing of two liquids, followed by discharge of the mixed liquids from the gun by the use of an air stream so that the mixture can be applied evenly and uniformly to a surface to be coated therewith.

In my US. Patent 3,229,911, issued Jan. 18, 1966, I disclose an improved spray gun for applying a two component mixture, such as an epoxy resin and curing agent. The problems which are encountered in the mixing and application by spraying of resinous materials which, when mixed, quickly set up to a hardened state, are described in some detail in my prior application. One of the major problems encountered is that of discharging the uniformly mixed materials immediately after such mixing in a manner which does not permit the resinous mixture to set up or become cured while still in the gun to the extent that the fluid conveyance channels within the spray gun become clogged and blocked. It is also diflicult to provide a spray gun which can be used over extended periods of time without requiring extensive and frequent cleaning.

The present invention comprises an improved spray gun for applying fluid mixtures of the type described, which gun can be operated over extended periods of time to apply a uniform mixture of resinous materials to a surface, and can be quickly cleaned as a result of a twopart construction which permits better access to be had to the channels or conduits within the gun through which the mixed materials must move following their mixture. Broadly described, the spray gun of the present invention comprises basically a two-part construction which includes a mixing head and a handle portion which is quick detachably secured to the mixing head during the use of the gun. The handle portion includes the valving employed in the fluid conduits provided inside the gun, and a trigger mechanism which permits such valving to be operated. The two-part construction of the gun thus provided greatly facilitates cleaning of the gun following its use, and also improves the ease with which the gun may be maintained by replacement or repair of valve parts, seals and the like.

3,417,923 Patented Dec. 24, 1968 "ice To further describe the construction of the spray gun of the invention, the mixing head portion of the gun includes a motor, a central body which is connected to the motor and a spray head secured to the central body on the opposite side thereof from the motor. The central body of the mixing head has formed therein a mixing chamber in which the several components of the fluid mixture are brought together and intimately mixed. The central body further includes a plurality of passageways which communicate with the mixing chamber for conveying a plurality of fluids to be mixed to the mixing chamber, and an air conduit which by-passes the mixing chamber and is provided for conveying air through the central body for a purpose hereinafter described. A mixing shaft is drivingly connected to the motor and extends into the mixing chamber formed in the central body of the mixing head. The spray head included in the mixing head includes an atomizing chamber, an air conduit means which interconnects the atomizing chamber with the air conduit in the central body, and a fluid passageway which interconnects the mixing chamber in the central body with the atomizing chamber.

The handle portion which is detachably connected to the mixing head in the spray gun of the invention includes a hand grip member which has formed therein a plurality of passageways which are positioned to communicate with the respective passageways in the central body of the mixing head portion. The hand grip member also defines an air conduit position therein for communicating with the air conduit in the central body at such time as the handle portion is operatively secured to the mixing head. The handle portion of the spray gun also includes valve means which is movably positioned in the passageways and air conduit carried by the hand grip member, and which functions to alternately open and close the passageways and air conduit. The valve means includes stem means which extends through the hand grip member to the outside thereof and cooperates with a trigger which is pivotally secured to the hand grip member, and used by the operator to open and close the valve means permitting the fluids which are to be mixed and the air to flow through the fluid passageways and the air conduits, respectively. Finally, means are provided in association with the fluid passageways and air conduit located in the hand grip member of the handle portion to facilitate the connection of flexible fluid supply conduits to these passageways and to the air conduit for supplying the fluids to be mixed to the spray gun, along with compressed air for atomization purposes as hereinafter described.

In a preferred embodiment of the invention, the spray gun further includes a solvent channel which is formed through the hand grip member of the handle portion and communicates with fluid passageways in the central body of the mixing head, these fluid passageways in turn being connected with the mixing chamber so that, for purposes of cleaning the gun and removing all residual mixture therefrom, a cleaning solvent can be directed into the mixing chamber and out through the passageways in the spray head.

From the foregoing description of the invention, it will have become apparent that an important object of the invention is to provide a spray gun for intimately mixing a plurality of fluids to provide a mixture of the type which sets up rapidly to a hardened state upon exposure to air, such spray gun being constructed to include a plurality of parts which may be quickly disconnected to facilitate cleaning and maintenance of the gun.

Another object of the present invention is to provide a mechanically simple, relatively economically constructed spray gun which can be used for providing a curable, epoxy resin mixture, and for dispensing such mixture in a finely divided state against substantially any surface which it is desired to coat with the mixture.

A further object of the present invention is to provide a spray gun for mixing a plurality of fluids and discharging the mixture in an atomized state, which gun is characterized in having relatively few moving parts which are, in each case, accessible for cleaning and maintenance when the gun is not in use.

In addition to the foregoing described objects and advantages, additional objects and advantages will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings which illustrate a. preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a view in elevation of a spray gun con structed in accordance with the invention.

FIGURE 2 is a sectional view taken through the spray gun along line 22 of FIGURE 1.

FIGURE 3 is a sectional view taken through the center of the spray gun in a longitudinal direction, but illustrating the motor used in the gun in elevation.

FIGURE 4 is a view in section taken along line 44 of FIGURE 3.

FIGURE 5 is a View in section taken along line 55 of FIGURE 3.

FIGURE 6 is a view in section taken along line 6-6 of FIGURE 3.

FIGURE 7 is an end view of the spray gun partly in section and partly in elevation depicting the orientation of the fluid passageways and air conduit in the handle portion of the gun.

Referring to the drawings in detail, and initially to FIGURE 1, the spray gun of the invention includes, as previously indicated, a mixing head designated by reference numeral 10 and a handle portion designated generally by reference numeral 12. Considering first, the construction of the mixing head 10, this part of the spray gun includes a motor 14 which, in the illustrated embodiment, is actuated by air introduced thereto by an air conduit or line 16. An internally threaded collar 18 is dimensioned for engagement with external threads formed around the casing of the motor 14 (see FIGURE 3). The collar 18 includes a beveled or undercut forward edge 20 and is provided for a purpose later to be described. The casing of the motor 14 includes a threaded projection 22 which is dimensioned for engagement with a threaded bore 24 formed in a central body 26 of the mixing head 10. A gasket 28 is provided around the threaded projection 22 between the motor 14 and the central body 26.

The central body 26 has formed therein a mixing chamber 30 which communicates with a counterbore 32 which in turn communicates with the threaded bore 24. The counterbore 32 is threaded to receive a threaded, annular sealing plug 34 which has secured thereto, an annular resilient sealing element 36. It will be noted that the annular sealing element 36 includes a radially inwardly extending, thin, flexible lip portion. The flexible lip portion of the annular sealing element 36 bears against a mixing shaft 38 which is secured at one of its ends in a retaining chuck 40 mounted on one end of the shaft of the motor 14. The opposite end of the mixing shaft 38 is positioned adjacent a frustoconical recess 42 formed in the central portion 44 of a spray head designated generally by reference numeral 46, and hereinafter described in greater detail. An annular bearing sleeve 47 is pressed into the end of the mixing chamber 30 in a mating groove and journals the shaft 38 intermediate its length. It will be noted in referring to FIGURE 3 that the mixing shaft 38 is provided with a plurality of circumferentially spaced, axially extending grooves 38b and with a right hand helical thread 380 over that portion of the shaft which is located in the mixing chamber 30'. A left hand helical thread 38d is provided on the portion 4 of the shaft 38 which extends through the bearing sleeve 47.

With this construction of the mixing shaft 38 and its arrangement relative to the bearing sleeve 47 and annular sealing element 36, the better lubricant of the two fluids to be mixed can be introduced as hereinafter explained to the counterbore 32. It will then force the lip portion of the sealing element 36 into sealing engagement with a smooth portion of the shaft 38 and will simultaneously lubricate this lip portion, the shaft and the bearing sleeve 47. The component in the counterbore 32 also functions to cool these frictionally engaged elements and prevent the shaft from heating up so as to accelerate the curing to a hardened state of the mixture in the mixing chamber 30 after the components are mixed therein.

The helical thread 38d on the mixing shaft 38 functions as a pump to move the fluid from the counterbore 32 through the bearing sleeve 47 into the mixing chamber 30. The turning of the mixing shaft 38 also prevents any of the mixture in the mixing chamber 30 from backing up through the bearing sleeve 47 into the counterbore 32, even though the flow of fluid into the counterbore 32 for subsequent pumping by the shaft into the mixing chamber 30 is interrupted.

Finally, the thread 38c on the portion of the shaft 38 in the mixing chamber 30 does not pump the mixture formed therein as hereinafter described, but rather performs a mixing action by the introduction of shear forces in the mixture in the mixing chamber.

The central body 26 further includes an externally threaded protuberant end portion 50, and a downwardly depending shoulder 52. As best illustrated in FIGURE 3, the central body 26 has formed therein an air conduit 54 which has a first portion 54a relatively closely adjacent, and extending parallel, to the mixing chamber 30 and opening in the end of the protuberant end portion 50. The air conduit 54 also has an intermediate portion 54b extending substantially normal to the first portion 54a, and also normal to a third portion 54c which extends parallel to the first portion and intersects and communicates with a nipple receiving bore 56.

In addition to the air conduit 54 formed through the central body 26 of the mixing head 10, the central body also has formed therein, as best illustrated in FIGURE 2, a pair of fluid passageways 58 and 60. The fluid passageway 58 includes a portion 58a (illustrated in FIGURE 2) lying in the same plane as the intermediate portion 54b of the air conduit 54 and extending into communication with the mixing chamber 30 which receives the mixing shaft 38. The fluid passageway 58 also includes a second portion 58b which extends normal to its portion 58a which communicates with the mixing chamber 30. It may also be pointed out in further clarification that the portion 58b of the fluid passageway 58 extends substantially parallel to that portion 540 of the air conduit 54 which intersects and communicates with the nipple receiving bore 56 formed in the downwardly depending shoulder 52 of the central body 26. The portion 58b of the fluid passageway 58 also intersects and communicates with a nipple receiving bore (not seen) which extends substantially horizontally with respect to, and is spaced from, the nipple receiving bore 56 in the downwardly depending shoulder 52.

The fluid passageway 60 depicted in FIGURE 2 includes a first portion 60:: which extends parallel to the mixing chamber 30 and enters the counterbore 32. The portion 60a of the fluid passageway 60 is depicted in dashed lines in FIGURE 3. The intermediate portion 60b of the fluid passageway 60 interconnects the portion 60a with a third portion 606 which extends parallel to the portion 60a and to the portion 58b of the fluid passageway 58. The portion 600 of the fluid passageway 60 also intersects and communicates with a nipple receiving bore (not shown) formed in the downwardly depending shoulder 52 of the central body 26 and extending substantially parallel to the nipple receiving bore 56. The function of the fluid passageways 58 and 60, and of the air conduit 54 will be hereinafter explained.

As has previously been indicated, a spray head 46 is secured to the central body 26 of the mixing head and includes a central portion 44. The central portion 44 has a central bore 64 extending therethrough and communicating with the mixing chamber 30. The central portion 44 of the spray head 46 also is provided with a plurality of angularly extending passageways 66, each of which communicates at one of its ends with an annular groove 68, and at its other end with a space 70 provided between a spray head tip 72 and the central portion 44 of the spray head 46. The spray head tip 72 has a central opening 73 formed in the end thereof and communicating with an atomizing chamber 75. The spray head tip 72 is secured to the central portion 44 by a locking collar 74 which threadedly engages both of these elements, as illustrated in FIGURE 3. At its side opposite that which is connected to the spray head 72 the central portion 44 is provided with an externally threaded nipple 76 which is adapted to be screwed into a spray head collet 80. The spray head collet 80 is provided with a large, internally threaded bore 82 which permits the assembled spray head 46 to be threadedly engaged with the externally threaded protuberant end portion 50 of the central body 26. An annular manifold groove 84 is provided at the base of the internally threaded bore 82 in the spray head collet 80 at a position to receive air from the air conduit 54 when the spray head collet is engaged with the central body 26. This annular manifold groove '84 communicates through a plurality of passageways 85 with an annular groove 86 disposed on the opposite side of the spray head collet 80 and in alignment with the annular groove 68 formed in the central portion 44.

The handle portion 12 of the spray gun of the invention includes a hand grip member 92 which has an enlarged, shaped neck portion 93 for receiving the mixing head 10. A trigger 94 is pivotally secured to the hand grip member 92 by a pivot pin 96 secured between a pair of protuberant ears 98. The handle 94 is bifurcated and thus includes a yoke 100 which is positioned at its upper end and engages a connecting link 102 which interconnects the valve stems of three valve elements as hereinafter explained. The hand grip member 92 includes various passageways, conduits and valve chambers, as best illustrated in FIGURES 3 and 7. Extending upwardly in the hand grip member 92 from the base thereof are an air conduit 104 and a pair of fluid passageways 106 and 108 which extend in substantially the same plane and parallel to the air conduit 104 (see FIGURE 7). Toward the forward side of the hand grip member 92, a solvent passageway 110 extends from the base of the hand grip member 92 upwardly therein (see FIGURE 3). At its upper end, the air conduit 104 enters a valve bore 112 which is closed by a threaded valve plug 114 having an axial bore therethrough which slidingly receives a valve stem 116. A sealing cap 118 is threaded on the outer end of the threaded valve plug 114 and compresses a sealing ring 120 into sealing engagement with the valve stem 116. At its outer end, the valve stem 116 passes through, and is secured to, the connecting link 102. At its opposite, or internal end, the stem 116 carries a generally conically shaped valve element 122. The valve element 122 seats in a centrally apertured valve seat 124 which is mounted in a counterbore 126. A helical spring 127 is provided for retaining the valve element 122 in its seated position. The counterbore 126 is threaded over a part of its length to receive a nipple 128 which projects beyond the neck portion 93 of the hand grip member 92, and is dimensioned to fit snugly in the nipple receiving bore 56 in the downwardly depending shoulder 52 of the central body 26 of the dispensing head 10. This relationship is best shown in FIGURE 3. An annular sealing ring 132 is provided around the protuberant portion of the nipple 128 to sealingly seat the nipple in the nipple receiving bore 56 when the handle portion 12 of the gun is attached to the mixing head, as hereinafter described. The nipple 128 has an axial bore 133 therethrough and is surrounded by a circumferential groove 134 which has a plurality of radial passageways 135 extending inwardly therefrom into communication with the axial bore 133.

The arrangement which has been described as characterizing the bore 112 and counterbore 126 and the valve elements which are located therein is also characteristic of two additional horizontally extending bores and counterbores and valve elements provided to convey fluid from the fluid passageways 106 and 108 into the corresponding fluid passageways 58 and in the central body 26 of the dispensing head 10. In other words, identical valving is provided in the hand grip member 92 in bores formed parallel to the bore 112 and identical in shape and dimension thereto. These bores (other than bore 112) are not visible in the drawings, but the counterbores which communicate with them can be seen in FIGURE 4 and are identified by reference characters 136 and 137. The nipples 138 and 139 located in these counterbores are formed substantially identically to the nipple 128 hereinbefore described and are dimensioned to mate with a pair of corresponding nipple receiving bores (not visible) formed in the downwardly depending shoulder 52 of the central body 26 of the dispensing head 10. Each of the nipples 138 and 139 are provided with an axial bore, a circumferential groove, and radial passageways corresponding to the axial bore 133, circumferential groove 134, and radial passageways formed in the nipple 128, these being designated by reference numerals 138a, 13% and 138C, and 139a, 13% and 1390 in the case of nipples 138 and 139, respectively. The shafts of the valves which operate in the bores communicating with the counterbores 136 and 137 are perceptible in FIGURE 7, and are identified by reference numerals 140 and 141. The valve stems 140 and 141 are, like the valve stem 116, passed through and secured to the connecting link 102 for common operation by the yoke 100 of the trigger 94.

At their lower ends which are opposite the bores which carry the valve elements, the air conduit 104 and the fluid passageways 106 and 108 communicate with internally threaded sockets 144, 146 and 148, respectively, so that a suitable air conveying conduit 149 and fluid conduits 150 and 151 can be secured to the base of the handle portion 12 of the gun by threaded fittings 152, 153 and 154. The solvent channel 110 located toward the front of the hand grip member 92 of the gun also has an internally threaded bore 156 formed at its lower end to facilitate connection of a solvent conduit 158 thereto through a suitable fitting 160. At its upper end, the solvent channel has a branch 162 which extends generally parallel to the bore 112 and counterbore 126 (as shown in FIGURE 3). The solvent channel branch 162 intersects a pair of angularly disposed solvent conduits 164, 166 (see FIG- URES 3 and 4) which communicate with the counterbores 136 and 137 formed in the neck portion 93 of the handle portion 12. Solvent may thus be conveyed through the hand grip member 92 into the counterbores 136 and 137 and through the small radial apertures 138a and 139c formed in the nipples 138 and 139 so as to permit a sol vent to be used to completely clean all parts of the gun downstream from the valves which control the flow of fluids therethrough. Suitable check valves 167 are provided in the angularly disposed solvent conduits 164 and 166 to prevent flow of fluids being mixed in the gun during its operation from the passageways 58 and 60 back into the solvent channel 110 via the nipples 138 and 139.

As final elements of the assembly which should be described before turning to the operation of the spray gun, the neck portion 93 of the handle portion 12 of the spray gun includes an undercut flange 170 which is engaged by the undercut forward edge 20 of the collar 18 which threadedly engages the casing of the motor 14. This engagement, along with the engagement of the nipples 128, 138 and 139 with their respective nipple receiving bores, permits the handle portion 12 to be firmly secured to the mixing head 10 during the operation of the gun. A suitable hook 171 is secured in the central body 26 to permit the gun to be hung in storage when not in use.

Operation At the time that the spray gun is to be utilized, the handle portion 12 is attached to the mixing head 10 by plugging or inserting the nipples 128, 138 and 139 into their respective nipple receiving bores, all of which are identical to the nipple receiving bore 56 shown in FIG- URE 3. The collar 18 will then be threaded on the threads which surround the casing of the motor 14 until the undercut forward edge 20 of the collar 18 engages and interlocks the undercut flange 170 formed on the neck portion 93 at the upper end of the hand grip member 92. The handle portion 12 is thus locked in engagement with the mixing head 10.

The fluid conduits 149, 150 and 151 are then secured to the base of the hand grip member 92 in the threaded sockets 144, 146 and 148, respectively, for the purpose of supplying air to the air conduit 104 and for supplying resin and catalyst to the fluid passageways 106 and 108, respectively. A solvent conduit 158 is also connected by the fitting 160 to the threaded bore 156 for supplying a cleaning solvent to the solvent channel 110. The solvent conduit 158 may, however, be left disconnected from the spray gun until its use has been completed and it is desired to clean the gun, if this procedure should be desired. The check valves 167 will function to prevent flow of the fluids to be mixed back into the solvent channel 110 or solvent channel branch 162. The final connection which is made to the spray gun is of the air conduit or line 16 which is connected to a suitable fitting on the air driven motor 14. This air line 16, of course, supplies the power fluid to the motor 14 from a suitable source of compressed air.

With the air conveying conduit 149 and the fluid conduits 150 and 151 connected to the base of the hand grip member 92 in the manner described, and also to suitable sources of resin, catalyst and compressed air, the gun is ready for use. Upon depression of the trigger 94, the valve stems 116, 140 and 141 are reciprocated through their respective valve plugs 114 so as to open the valves by withdrawing the valve elements 122 from their respective seats. This action permits resin and catalyst to flow through the passageways 106 and 108 in the hand grip member 92 into their bores corresponding to the bore 112, through the apertures in the valve seats in these bores and into the axial bores 133, 138a and 139a in the nipples 128, 138 and 139, respectively. After leaving the respective nipples, the compressed air, catalyst and resin flow through their diiferently oriented flow conduits or passageways in the shoulder portion 52 of the central body 26. Thus, the resin from the fluid passageway 106 and the nipple 138 moves through the fluid passageway 60 into the counterbore 32 formed in the central body 26 of the mixing head as depicted in FIGURE 3. Here the resin acts against the flexible lip portion of the sealing element 36 to force it against the shaft 38. The resin also functions to lubricate and cool the sealing element 36 and the bearing sleeve 47. The left hand thread on the shaft picks up the resin and pumps it forward into the mixing chamber 30.

The flow of the catalyst which is to be mixed with the resin occurs through the fluid passageway 58 so that the resin enters the mixing chamber 30 at a point adja cent approximately the center of the mixing shaft 38 as best depicted in FIGURE 2. At this point within the mixing chamber 30, the catalyst and the resin are mixed in the proper proportion to provide the coating composition which is to be applied with the spray gun. The right hand helical thread 380 on the portion of the mixing shaft 38 in the mixing chamber 30 works against the flow of both fluids so as to induce turbulence in the mixture. Shearing action is developed in the mixture by the axial grooves 38b in the mixing shaft 38.

During the occurrence of the described mixing in the mixing chamber 30, compressed air is delivered from the air conduit 104 through the bore 112 and through the axial bore 133 in the nipple 28, thence through the passageway 54 and into the annular manifold groove 84 provided in the spray head collet 80. From the annular manifold groove 84, the air moves through the passageways 85 into the annular groove 86 and the registering annular groove 68 which is formed in the central portion 44 of the spray head 46. The air then is directed through the angularly extending passageways 66 into a space 70 which is provided between the spray head tip 72 and the central portion 44 of the spray head 46. As the air is ejected under pressure through the Opening 73 formed in the spray head tip 72, suction or vacuum is created within the central bore 64 in the central portion 44 to draw the mixed resin and catalyst through the central bore 64 and into the spray head tip 72. The intimate mixture of finely divided catalyst and resin with air is discharged as a spray from the spray head tip 72 against whatever surface is to be coated with the mixture. The time lapse between the first instant of contact between the catalyst and resin until the mixture comes to rest upon the surface to be coated is relatively short and little opportunity is provided for the mixture to set up or harden in the assageways within the gun.

Upon completion of a spraying operation using the gun, it is desirable to purge with a cleaning solvent the fluid passageways, particularly that portion of the flow channels within the gun which carry the catalyst and resin after they have been mixed. The cleaning material used should be a solvent for the mixture and for each of the individual components so that the flow passageways with in the gun are completely clean following use of the gun. To this end, a cleansing solvent can be directed through the solvent channel 110, thence through the branch solvent channel 162, the solvent conduits 164 and 166 in the neck portion 93 of the hand grip member 22, and finally through the radial apertures 138c, 139c formed in the nipples 138 and 139. The solvent moves from this point through the fluid passageways 60 and 58 and into the mixing chamber 30. The solvent then follows the course of the resin-catalyst mixture through the axial grooves 38b in the mixing shaft 38, through the central bore 64 formed in the central portion 44 of the spray head 46 and ultimately passes out of the spray head tip 72 through the central aperture 73 formed therein. A complete cleansing of all passageways which are contacted by the resin and the catalyst downstream from the valve elements located in the neck portion 93 of the hand grip element 92 is thus effected.

After the spraying operation has been completedand the fluid passageways have been cleaned with a solvent in the manner described, the spray gun may be disassembled or broken down into its several parts by unscrewing the collar 18 from the engaging threads on the casing of the motor 14 so as to permit the undercut forward edge 20 of the collar to be released from the undercut flange on the neck portion 93 of the hand grip member 92. The nipples 128, 138 and 139 are then detached from their respective nipple engaging bores in the shoulder 52 of the mixing head 10. This permits the handle portion 12 of the gun to be completely detached from the mixing head 10. The respective fluid passageways in both the mixing head 10 and the hand grip portion 92 can then be further cleaned by gravitating solvent therethrough or by a compressed air blast, as may be required.'It will fur ther be noted that disconnection of the handle portion 12 from the mixing head also facilitates access to the various moving parts of the spray gun so that the valves may be repaired or replaced as may be necessary, and the mixing shaft 38 may be completely removed from the mixing chamber 30 to facilitate cleaning or replacement if this should be desired.

When the spray gun is not in use, it may be conveniently hung over a suitable hook or nail by means of the hanger 171.

From the foregoing description of the invention, it will have become apparent that the present invention provides an improved, efiicient spray gun for mixing a plurality of fluids in an intimate manner preparatory to discharging the mixture in the form of a mist or spray into a cavity to be filled or onto a surface to be coated. The construction of the spray gun in readily disassembled parts permits it to be cleaned and maintained easily. Relatively few moving parts are employed and the overall construction of the spray gun permits it to be economically manufactured.

Although a specific embodiment of the invention has been herein disclosed in order to provide an example of the manner in which the invention may be constructed, it

is to be understood that various structural elements depicted in the drawings and herein described may be altered in configuration, or may be replaced by equivalent structures without departure from the basic principles which underlie the invention. All such modifications and innovations are therefore deemed to be circumscribed by the spirit and scope of the invention except as they may be necessarily limited by the appended claims or reasonable equivalents thereof. What is claimed is: 1. A spray gun for applying a mixture of a plurality of components comprising:

(a) a mixing head including:

amotor; a central body connected to said motor and having formed therein;

a mixing chamber;

a plurality of passageways communicating with said mixing chamber at different 10- cations therein for conveying a plurality of fluids to be mixed to the mixing chamber; and

an air conduit for conveying air through said central body;

a mixing shaft drivingly connected to said motor and extending into said mixing chamber; and

a spray head connected to said central body and having formed therein an atomizing chamber;

air conduit means interconnecting said atomizing chamber with the air conduit in said central body; and

a fluid passageway interconnecting the mixing chamber in said central body with said atomizing chamber; and

(b) a handle portion detachably connected to said mixing head and including:

a hand grip member having formed therein:

a plurality of fluid passageways communicating with the passageways in the central body of said mixing head when said mixing head and handle portion are operatively connected to each other; and

air conduit means communicating with the air conduit in said central body of the mixing head when said mixing head and handle portion are operatively connected to each other;

valve means movably positioned in the fluid passageways and air conduit means in the hand grip member for alternately opening and closing the passageways and air conduit means in the hand grip member;

a trigger pivotally secured to the hand grip member and engaging said valve means to open and close said valve means upon actuation of the trigger; and

means associated with said fluid passageways and air conduit means in said hand grip member faciliating connection of fluid conduits to said hand grip member in communication with each of the fluid passageways and the air conduit means in said hand grip member.

2. A spray gun as defined in claim 1 and further characterized to include a solvent passageway in said hand grip portion and communicating with the fluid passageways in said handgrip portion at points therein downstream from said valve means.

3. A spray gun as defined in claim 1 wherein said valve means comprises:

valve seats positioned in said hand grip member in said air conduit means and in each of said fluid passageways;

valve elements movably positioned in each of the fluid passageways in said hand grip member and in the air conduit means therein and positioned to sealingly engage said valve seats;

valve stems secured to each of said valve elements and extending through said hand grip member to the outside thereof; and

means operatively connecting the ends of said valve stems outside said hand grip member with said trigger for simultaneous seating and unseating of the valve elements by manipulation of the trigger.

4. A spray gun as defined in claim 3 wherein said valve elements and valve stems are detachable from said hand grip member.

5. A spray gun as defined in claim 1 wherein said motor is an air driven motor.

6. A spray gun for applying a mixture of a plurality of components comprising:

(a) amixing head including:

amotor; a central body connected to said motor and having formed therein:

a mixing chamber;

a plurality of fluid passageways communieating with said mixing chamber for conveying a plurality of fluids to be mixed to the mixing chamber;

an air conduit for conveying air through said central body; and

a plurality of nipple receiving bores and communicating respectively with said fluid passageways and with said air conduit;

a mixing shaft drivingly connected to said motor and extending into said mixing chamber; and

a spray head connected to said central body and having formed therein an atomizing chamber;

first air conduit means interconnecting said atomizing chamber with the air conduit in said central body; and

a fluid passageway interconnecting the mixing chamber in said central body with said atomizing chamber; and

(b) a handle portion detachably connected to said mixing head and including:

a hand grip member having formed therein:

a plurality of nipples projecting from said hand grip member and positioned and dimensioned for frictional engagement with said nipple receiving bores when said handle portion is detachably connected to said mixing head;

a plurality of fluid passageways communi- 11 cating through someof said nipples with the air conduit in said central body of the mixing head when said mixing head and handle portion are operatively connected 12 a fluid passageway interconnecting the mixing chamber in said central body with said atomizing chamber; and

(b) a handle portion detachably connected to said mixto each other; and ing head and including: valve means movably positioned in the fluid p'asa hand grip member having formed therein:

sageways and second air conduit means in the a plurality of fluid passageways communihand grip member for alternately opening and eating with the passageways in the central closing the fluid passageways and second air body of said mixing head when said mixing conduit means in the hand grip member; head and handle portion are operatively a trigger pivotally secured to the hand grip memconnected to each other; and

her and engaging said valve means to open and second air conduit means communicating close said valve means upon actuation of the with the air conduit in said central body trigger; of the mixing head when said mixing head means associated with said fluid passageways and 15 and handle portion are operatively consaid second air conduit means in said hand grip nected to each other; member facilitating connection of fluid convalve means movably positioned in the fluid pasduits to said hand grip member in communicasageways and second air conduit means in the tion with each of the fluid passageways and the hand grip member for alternately opening and second air conduit means in said hand grip closing the passageways and second air conduit member; means in the hand grip member; I flange means secured to said hand grip member; a trigger pivotally secured to the hand grip mema collar threadedly engaging said mixing head and ber and engaging said valve means to open and engageable with said flange means when said close said valve means upon actuation of the handle portion is detachably connected to said trigger; and mixing head. means associated with said fluid passageways and 7. A spray gun as defined in claim 6 wherein said second air conduit meansinsaid hand grip memnipples are detachably positioned in the fluid passageber facilitating connection of fluid conduits to ways and air conduit means in said hand grip member. said hand grip member in communication with 8. A spray gun as defined in claim 6 wherein said each of the fluid passageways and said second mixing shaft has axially extending grooves circumferair conduit means in said hand grip member.

10. A spray gun for applying a mixture of a plurality of components comprising: a mixing head including:

entially spaced around its outer periphery and further has a helical thread formed over a major portion of its length;

and wherein said valve means comprises:

valve seats positioned in said hand grip member in said air conduit means and in each of said fluid passageways;

a motor; a central body connected to said motor and having formed therein valve elements movably positioned in each of the amixing hamber;

fl id passageways in said hand grip member and a bore aligned with and communicating with in the air conduit means therein and positioned said mixing chamber;

to scaling engage said valve seats; valve stems secured to each of said valve elements and extending through said hand grip member to the outside thereof; and means operatively connecting the ends of said valve stems outside said hand grip member with said trigger for simultaneous seating and unseating of the valve elements by manipulation of the trigger. 9. A spray gun for applying a mixture of a plurality of components comprising:

(a) a mixing head including:

a first passageway communicating with said mixing chamber for conveying a fluid to be mixed to said mixing chamber;

a second passageway communicating with said bore for conveying to said bore a fluid to be mixed with said first mentioned fluid;

an air conduit for conveying air through said central body;

'a mixing shaft drivingly connected to said motor and extending through said bore and said mixing chamber, said mixing shaft having a first helical thread formed therearound over a pora motor; tion of the shaft between said bore and said mixa central body connected i0 sa1d motor and having ing chamber and directed for pumping a fluid formed therein: from said bore to said mixing chamber when said a mixing chamber;

a plurality of passageways communicating with said mixing chamber for conveying a plurality of fluids to be mixed to said mixing motor is energized, and said shaft having a second helical thread formed around a portion thereof in said mixing chamber and directed in a direction opposite said first helical thread for c a fi f 0 0 introducing shear forces in a mixture in said an air conduit for conveying air to sa1d cenmixingchambertl'al body, a flexible sealing element surrounding, and beara mixing shaft drivingly connected to said motor and extending into said mixing chamber, said mixing shaft having axially extending grooves circumferentially spaced around its outer periphery and further having a helical thread formed over a portion of its length disposed in said mixing chamber; and

a spray head connected to said central body and having formed therein an atomizing chamber;

first air conduit means interconnecting said atomizing chamber with the air conduit in said central body; and

a handle portion connected to said mixing head and including:

a hand grip member having formed therein:

fluid passageways communicating with the first and second passageways in the central air conduit means communicating with the air conduit in said central body of said mixing head; and air conduit means communicating with the air conduit on said central body of the mixing head; valve movably positioned in the fluid passageways and air conduit means in the hand grip member for alternately opening and closing the fluid passageways and air conduit means in the hand grip member; and 1 a trigger pivotally secured to the hand grip mem her and engaging said valve means to open and close said valve means upon actuation of the trigger.

11. A spray gun as defined in claim 10 wherein said flexible sealing element includes an annular body of resilient material having a thin, radially inwardly extending sealing lip contacting said mixing shaft and configured to be biased by fluid pressure acting along said shaft in the direction of said motor into more tenacious sealing engagement with said shaft.

References Cited UNITED STATES PATENTS 1,361,527 12/1920 Johns 239527 X 1,987,248 1/1935 Seizer 239-527 X 3,116,878 1/1964 Reiter 239-142 3,176,922 4/1965 Decker 239-112 3,304,010 2/1967 Cantrell et a1. 239-142 M. HENSON WOOD, JR., Primary Examiner.

H. NATTER, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,417,923 December 24, 1968 Ronald E. Carlson Column 12, line 73, beginning with "fluid passageways" cancel all to and including "mixing head; and" in line 2, column 13, and insert instead fluid passageways communicating with the first and second passageways in the central body of said mixing head; and Column 13, line 4, "on" should read in line 6, "valve" should read valve means Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

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