US2348568A - Spray gun - Google Patents

Description

May 9, 1944- R. R. PELLAR 2,348,568

SPRAY-GUN Filed nec. 11, 1941 2lb M, f

' zvenw Ralcard Pella."

Patented May 9, 1944 UNITED STATES PATENT oFElcE SPRAY GUN Ralph Richard Pellar, Chicago, Ill.

Application December 11, 1941, Serial No. 422,481

6 Claims.

My invention relates to a nozzleor spray-head for a spray-gun or airbrush used for spraying paint or other surface coating materials and similar purposes.

Great difficulty has been experienced in conserving air introduced into the spray-head due to the employment generally of a tapered nozzle in a male and female relationship with the aircap to obtain an airtight tting of the parts. This has necessitated not only a precision in the machining of parts with consequent relatively high cost of the product but a multiplicity of parts, including baffles, springs, gaskets and other devices. These expedients generally have complicated the problem rather than contributed materially to its solution.

An object of my invention is to provide simple and efcient means for conserving the air introduced into the spray-head not only at the juncture of the spray-head and the body of the spraygun but alsoat the juncture of the air-cap and the spray-head. The'first is accomplished in my invention by providing the front portion of the body of the spray-gun with a shoulder or iiange having a downwardly extending portion or lug which serves as a leverage against a similar portion provided on the reverse of the sprayhead, the abutting surfaces being smooth for obtaining an air-tight abutment of the spray-head against the body of the spray-gun when the two are drawn together by means of -a screw nut acting upon a threaded projection of the sprayhead which extends through' an -opening in the flange of the air-gun body. The second is accomplished in 4my vinvention by substituting a nozzle of cylindrical surface for the tapered form heretofore generally used, thus eliminating the need for a high degree of precision in the tapering of the nozzle and the female interior of the air-cap, by providing a plurality of -spaced annular flanges on the rear-of the air-cap and making the abutting surfaces of the spray-head and the. air-cap smooth to permit air-tight seating of the air-capiagainst the spray-head, and by providing -a transverse annular flange in the interior of the air-cap with a plurality of spaced holes therethrough to afford the necessary air passages for the desired distribution of air and adapted to be mounted upon the cylindrical surface of the nozzle.

In the drawing which diagrammatically shows my invention- V Figure 1 is a side view of a spray-gun embodying my invention.

Figure 2 is a central longitudinal section of the forward `portion of the spray-gun shown in Figure 1.

Figure 3 is a front view of the body of the spray-gun shown in Figure l with the spray-head removed,

Figure 4 is a rear view of spray-head shown in Figure 1 removed from the body of the spraygun.

Figure 5 is a front View of the same sprayhead with the air-cap removed.

Figure 6 is a rear View of the air-cap shown in Figure 1.

Referring to the drawing, the spray-gun shown has a body portion I provided at its front end with a shoulder or flange 2 having a downwardly extending projection or lug 3. Abutting the forward end of the body I is spray-head I having a projection or stem 5 with a threaded end [i adapted to seat in opening 1, which is provided in flange 2 and has a slightly greater diameter than stem 5, the threaded portion 6 extending therethrough and being engaged by nut 8.

Air chamber 9 in the upper portion of body I, in which is seated adjustable needle valve Il), is fitted at its forward end with a sleeve I I which extends forwardly into an aligned air passage I2 in spray-head 4. A gasket I3 is seated in a recess I4 in the body I about the sleeve II. The abutting surfaces of the gray-head and body are smooth and the conformation of the parts is such that when fitted together and nut 8 'is tightened upon stem 5 an airtight juncture is formed. v

Nozzle I5, the threaded rear portion I6 of which is screwed into threaded forward lportion I'I' of material chamber AI8 of spray-head 4, instead of being tapered to engage an air-cap in male and female relationship, is cylindrical in form in its forward portion I5a and flat sided or polygonal in its middle portion I5b and provided intermediately with a groove |50. Nozzle I5 is also provided with a central tubular channel I5d, which is adapted to receive a needle valve, the

forward portion of the channel converging to sages 2I with a circular groove 2|d deilned by two concentric, rearwardly extending flanges 2le and 2If co-axial with orifice ZIE, in the rear of the air cap. The outer diameter of flange 2|", which also extends radially as indicated at 2Ig, is slightly less than the inner diameter of coupling I9. Flange 2|g is adapted to be engaged by flange I9b to secure the air-cap to the sprayhead, the flanges I9b, 2 Ie and 2 Igbeing of such conformation as to form an airtight connection between the air cap and the spray-head when the air-cap is coupled to the spray-head by tightly screwing the coupling I9 upon the threaded portion 4a of the spray-head. The inner diameter of flange 2If is substantially the same as the outer diameter of circular groove 22 which is provided in the face of spray-head 4 and is coaxial with flange 2 If. Y

Air-cap 2| is also provided with an internal annular flange or baille 2Ih which is co-axial with orifice 2 Ia and has an inner diameter slightly greatler than the cylindrical portion I@ of nozzle I5 upon which it is adapted to be slidably mounted. Flange 2Ih is provided with holes 2!i to permit suitable distribution of air about the forward portion of the nozzle. Y i

Spray-head 4 is provided with an air passage 23 connecting groove 22 with constricted portion I2a of air chamber I2, the forward end of which is still further constricted at l2b to form a seat for end 24 of needle valve I (which is adjustable through nut 27) but has an outlet I2 in communication with groove 2 Id.

Needle 20, which is journalled in stem 5 of the spray-head and is adjustable through screwhead 20, as shown in Figure 2, is normally held in position closing outlet I5e of the nozzle by means of a spring (not shown), but is rearwardly shiftable by rearward pressure upon trigger 25 which is pivoted to body I at 23 and engages stop 29h which is adjustably secured to needle 20.

The rear of the spray-head has a llanged portion 4c conforming with the face of the abutting flanged portion 2 of the body. Depending stem 4b of the spray-head is adapted to be connected with a source of material to be sprayed.

A suitable source of compressed air being provided and its admission to chamber 9 being controlled through trigger 25 by suitable valves (not shown) and the needles 20 and 2li being suitably adjusted, the operation of the spray-gun is as follows:

Air admitted to chamber 9 by rearward pressure upon trigger 25 passes through passage I2 including constricted portion I2n into passage 23 and groove 22 and thence around nozzle I5 through holes 2li and orifice 2la creating Suction about the outlet I5e of nozzle I 5, causing material to pass through chamber I8, channel I5d, around needle 20 and to issue from outlet I5e. Simultaneously with the passage of air as described, air also passes from constrictions I2a and I2b into groove 2Id and thence through passages 2Ic to issue from ports 2Ia and converge upon the material stream which, vissues from outlet I5e in the manner described in the aforesaid Letters Patent. This is accomplished in the construction shown without substantial loss of air at the junctures of the several parts.

The configuration of the parts may be varied to suit various undertakings without departing air chamber extending longitudinally therethrough and a peripheral shoulder at its forward end, said shoulder having a depending portion with a longitudinally extending opening therethrough and a downwardly extending projection below said opening, the axes of said chamber and opening being in the same vertical plane; a spray-head having an air passage in its upper portion extending longitudinally therethrough in axial alignment with said air chamber and a rearwardly extending stem in axial alignment with said opening and adapted to extend therethrough, the rear of said spray-head in other respects conforming to the front of said body; means connecting said -body and said sprayhead through said air chamber and the corresponding air passage in said spray-head; means adapted to engage the end portion of said stem and the rear surface of said projection to secure said body and said spray-head together in substantially airtight relationship; said stem having a longitudinally extending opening therethrough in which a needle may be movably mounted; said spray-head having a material chamber with an outlet having its axis in alignment with the axis of the opening in said stem and adapted to receive a nozzle; said spray-head also having inits face an annular air channel co-axial with said outlet and communicating with said air passage; a nozzle adapted to be seated in said outlet having a central longitudinally extending opening adapted to receive said needle with a constricted forward portion adapted to seat the forward portion of said needle and a cylindrical outlet; the external surface of said nozzle being cylindrical in its forward portion and polygonal in its middle portion and having an annular channel therebetween; an air-cap having a central material orice of slightly greater diameter than the cylindrical outlet of said nozzle, and a plurality of supplemental air ports spaced therefrom in opposed relation, each of said supplemental air ports communicating with a circular groove in the rear surface of said air cap defined by two concentric annular, longitudinally extending flanges thereon co-axial with said orifice, said flanges being adapted to seat against the forward portion of said sprayhead, and the outer flange extending radially to form a peripheral flange; said air-cap also having an internal ,annular flange co-axial with said orice adapted to be mounted upon the cylindrical portion of said nozzle and having circumferentially spaced longitudinal openings therethrough; said air-cap having a central opening in its rear portion whose diameter is coextensive with the outer diameter of said air channel; and means for securing said air cap in substantially airtight relationship to said spray-head; the conformation of the parts being such as to provide simultaneously for the creation of an airstream about the outlet of said nozzle and supplemental airstreams converging upon said first airstream in advance of said outlet without;Y substantial leakage of air through the connections of said parts.

2. In a spray-gun the combination of a body', a spray-head, a nozzle and an air cap; said bodyand spray-head being in juxtaposition, with a longitudinal conduit extending therethrough and being connected by a sleeve in saidv conduit therebetween, said body having al peripheral shoulder adjacent to said spray-head with a downwardly extending flange bored ylongitudinally substantially above its lower extremity, said spray-head having a rearwardly extending stem in axial alignment with the base of said flange and adapted to extend therethrough, and said body and spray-head being secured together in airtight relationship by means engaging said stem and the rear of said flange; said spray-head having a central frontal material outlet adapted to receive a nozzle and a substantially smooth face with an annular groove therein co-axial with said outlet, said groove communicating with said conduit; said nozzle being cylindrical for a substantial portion of its length and being adapted to be secured in said outlet; said aircap having a central material orice adapted to receive the forward portion of said nozzle, a plurality of supplemental air ports, a plurality of rear spaced annular ilanges co-axial with said orifice and defining an annular channel communicating with said air ports and with said conduit, said annular flanges abutting the face of the spray-head in a common plane and the inner diameter of the inner flange being coextensive with the outer diameter of said groove; said air-cap also having an internal annular flange adapted to be slidably mounted on the cylindrical portion of the nozzle; and said aircap and said spray-head being secured together in substantially airtight relationship.

3. A spray-gun comprising a body and a spray head, said body and said spray head having corresponding faces arranged in abutting relation, said body having an air chamber extending longitudinally therethrough and a peripheral shoulder adjacent its forward end, said shoulder having a depending portion with a longitudinally extending opening therethrough and a downwardly extending projection below said opening, the axes of said chamber and opening being in the same vertical plane, the distance from the axis of the opening to the bottom of said projection being from one-third to one-half of the distance from the bottom of the projection to the top of said shoulder, said spray-head having an air passage in its upper portion extending longitudinally therethrough in axial alignment with said air chamber and a rearwardly extending stem in axial alignment with said opening and adapted to extend therethrough, the rear of said spray-head in other respects conforming to the front of said body, means connecting said body and said spray-head through said air chamber and the corresponding air passage in said spray-head, and means adapted to engage the end portion of said stem and the rear surface of said projection to secure said body and said spray-head together; the parts being of such conformation as to form a substantially airtight juncture between said body and sprayhead when thus secured.

4. In a spray-gun, a body and a spray-head in juxtaposition, with a longitudinal conduit extending therethrough, a sleeve in said conduit therebtween, said body having a peripheral shoulder adjacent to said spray-head, said shoulder having a downwardly extending flange provided with a longitudinally extending bore and a depending portion below said bore, said depending portion extending below said bore a distance at least equal to the distance between the axis of said sleeve and the axis of said bore, the diameter of said bore and the diameter of said conduit being substantially equal, said spray-head having a rearwardly extending projection corresponding with and arranged to abut a surface of said depending portion and a stem in axial alignment with the bore of said flange and adapted to extend therethrough, and means adapted to engage said stem and said flange and secure the parts together, the parts being of such conformation as to form a substantially airtight juncture between said body and spray-head when thus Secured.

5. In a spray-gun, a body and a spray-head in juxtaposition, with a longitudinal conduit extending therethrough, a sleeve in said conduit therebetween, said body having a peripheral shoulder adjacent to said spray-head, said shoulder being provided with a downwardly extending ange bored longitudinally substantially above its lower extremity and having a depending nger below said opening, said spray-head having a stem in axial alignment with the bore of said ilange and adapted to extend therethrough, and means adapted to engage said stem and said flange and secure the parts together, said sprayhead having a rearwardly extending projection arranged to abut a surface of said finger and as the parts are thus secured together to cooperate with said ilnger and with said sleeve and the interior walls of said conduit to facilitate the bringing of said body and spray-head into juxtaposition and the formation of an airtight juncture between them, the parts being of such conformation and so arranged as to form a substantially airtight juncture between said body and spray-head when thus secured.

6. A spray-gun comprising a body and a sprayhead, each having a face arranged in abutting relation with a corresponding face of the other, said body having an air chamber extending longitudinally therethrough, said vspray-head having an air passage in its upper portion extending longitudinally therethrough in axial alignment and in open communication with said air chamber, means connecting said body and said sprayhead through said air chamber and said air passage, said body having a peripheral shoulder adjacent its said face, said shoulder having a depending portion provided with a longitudinally extending opening therethrough and a downwardly extending finger below said opening, said opening having its axis in the same vertical plane as the axis of said air chamber, said spray-head having a stem in axial alignment with said opening and adapted to extend therethrough and a projecting portion corresponding with said finger, and adjustable means adapted to engage an end portion of said stem and a surface of said finger to secure said body and spray-head together, said means being arranged to cooperate with said finger, said corre sponding projecting portion and said connecting means to adjust said faces in abutting relation, the parts being of such conformation and so arranged as to provide a substantially air tight juncture between said body and said sprayhead when thus secured.

RALPH RICHARD PELLAR.

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