US2475000A

US2475000A - Spray gun nozzle

Info

Publication number: US2475000A
Application number: US730983A
Authority: US
Inventors: Jr Howard Warren Beach
Original assignee: Eclipse Air Brush Co
Current assignee: Eclipse Air Brush Co
Priority date: 1947-02-26
Filing date: 1947-02-26
Publication date: 1949-07-05
Anticipated expiration: 1966-07-05

Description

- July 5, 1949. H. w. BEACH, JR i 2,475,000

SPRAY GUN NozzLE Filed Feb. 2e, 194'.'

Patented July 5, 1949 SPRAY GUN NOZZLE Howard Warren Beach, Jr., Montville, N. J., as-

signor to Eclipse Air Brush Co., Newark, N. J., a corporation of New Jersey Application February 2.6, 1947, Serial No. 730,983

2 Claims.

This invention relates to improvements in devices for spraying materials such as lacquers, varnishes, paints or semi-pastes, and particularly to sc-called spray guns that are designed to discharge a substantially fan-shaped spray stream.

An object of the invention is to provide a novel spray head or nozzle for use in conjunction with spray guns which facilitates effective control of the fan-shaped spray from a minimum narrow fan-spread width to a very wide fan-spread width to suit the particular job at hand. By fanshaped, I mean flaring or divergent in width but preferably of small depth or thickness.

Another object of the invention is to secure this effective fan-spread control by pneumatic or other gaseous means.

Still other objects are to provide means for increasing the atomization of the spray material along the outer fan edges, to make the device substantially self-cleaning, and to render it more universally adaptable for a larger variety of paints and other spraying materials.

A further object is to provide structure that is mechanically simple, highly ecient in operation, which utilizes a minimum of spraying material and air or gas pressure to accomplish the best atomizing results, and which is capable of use with existing spray guns.

To the accomplishment of the foregoing and such other objects and features as may hereinafter appear, this invention consists in the novel method, construction and arrangement of parts hereinafter to be described and then sought to be defined in the appended claims, reference being had to the accompanying drawing forming a part hereof, which shows, merely for the purposes of illustrative disclosure a preferred embodiment of the invention, it being expressly understood, however, that changes may be made in practice within the scope of the claims, without digressing from the inventive idea.

In the drawing wherein similar reference characters denote corresponding parts:

Fig. 1 represents a vertical longitudinal crosssection through a spray gun shown in closed condition to which the novel nozzle or spray head embodying the invention has been applied;

Fig. 2 is a horizontal longitudinal cross-section 4taken along line 2-2 of Fig. 1 and viewed in the Fig. 4 is a full end elevational view of the nozzle of Fig. 3 viewed lfrom the left thereof.

Referring to the drawings, I designates the body of the device as a whole, this body including the barrel portion 2 and the handle portion 3, the latter extending downwardly from the barrel portion and inclined slightly to the rear so that the device has somewhat the appearance of an automatic pistol.

Devices of this kind are employed to spra material principally for coating purposes, the material being atomized by air or other gas under pressure. In general the spray gun illustrated has the construction disclosed in Austin I-I. Downs U. S'. Patent No. 2,228,226, granted January '7, 1941. Other types of spray guns, however, may be employed. The material to be sprayed is fed to the point of atomization by pressure and consequently the spray gun has ports, passages and valves for controlling the admission and passage of the pressure uid, as well as the liquid material and the atomization of the same.

In the embodiment shown, a hose connection Ll to a suitable source of air or other gaseous uid under pressure is connected at 5 at the bottom of the handle portion 3 to a passageway 6 which extends upwardly through the handle 3 to the air inlet valve chamber 1. This chamber has a valve seat 8 at one end of a distributing chamber 9. A connecting passageway I0 leads from the distributing chamber to a passageway Il which eX- tends through the barrel towards its nozzle end. A second connecting passageway I2 leads from the distributing chamber 9 to a Valve chamber I3. A spring-pressed valve body I4 which is seated normally in closed position on the valve seat 8 is carried in the inlet valve chamber l. The operating stem l5 of the valve body is engageable by a trigger I6. This trigger is secured pivotally at l1 and when drawn toward the handle 3 operates the stem l5 to unseat the valve I4 from seat 8, thereby opening passageway II and valve chamber I3 to fluid pressure.

The valve chamber I3 is connected to a passageway I8 through a valve seat I9. The passageway I8 extends forwardly within the barrel 2 towards its nozzle end. A manually operable adjustable needle valve 20 controls ow of gaseous pressure fluid to the passageway I8 from the valve chamber I3. It may be set yto cut-off engagement on the valve seat I9 and be moved off the seat as desired to regulate flow of air or other gaseous pressure fluid to the passageway I8 for purposes presently to be described.

The air passages I I and 'I8 extend along the A passageway 23, ,ex-

Such a pressure feed cup is described in the Downs Patent No. 1,706,875.

In operation, it being understood that a source of fluid under pressure is connected to the extension 29, and that a source of air or gas pressure is connected to the connection 4, the operator presses the trigger I5. This immediately opens the valve I4 whereby a supply of air or gas under pressure is admitted into the air or gas distributing chamber 9 and from there to the passages I0, II, 23 and from thence through the slots 35 and clearances about the uid tip 34 into the atomizing chamber 44. Likewise, air or gas is admitted to the needle valve chamber I3 through the passageway I2 but since needle Valve 2B is closed initially the air or gas is blocked from the passageway I8.

The air or gas from passageway 23 under pressure passes through the slots 35 in the fluid tip 3B and the spaces or clearances between the tip and nozzle 42 and across the end 34 of the tip 30 and then strikes the shoulders 44a of the nozzle, being thereby deected and then out through the fan slot 5I. Since the trigger I6 has not yet moved the valve rod 38, there is no passage of paint or other coating liquid, and this does not occur until air or gas under pressure is flowing through and emerging from the nozzle slot 5I. Further movement of the trigger I6 retracts the valve rod 38 unseating valve 3'! from its seat 35a. This permits the paint or other coating fluid delivered under pressure to chamber 26 through passageway 21 to pass through the fluid tip bore 36 to its outlet end in nose 34. Then the uid meets the outrushing current of air or gas under pressure and is completely broken up and atomized and forced out of the fan slot passage 5I in the form of a fan-like sheet of misty uid material for application as a surface coating. The spread of the emerging fan spray is widest at this time while the needle valve 20 remains closed.

To decrease the fan spread of the spray for accommodation to the surface to be coated, the needle valve 20 is now opened to permit flow of air or gas under pressure from valve chamber I3 through passageways I8, and 24 into annular space 48a and thence through passageways 49 and 5I! and the oppositely directed

inclined passageways

52, 53 whose respective outlets lie adjacent the opposite sides of the fan slot 5I. The jets of air or gas emerging under pressure from these outlets strike the opposite side edges of the fan spray emerging from the fan slot 5I and operate to reduce the fan spread. At the same time they operate to increase the atomization of the spray particles particularly those at the outer edges of the fan spray. The degree of reduction in fan spread effected by these oppositely directed jets from the

passageways

52 and 53 depends upon their volume and velocity and these are controlled as desired by regulation of the needle valve 20. If the latter is wide open, minimum fan spray spread is effected. If the needle valve 2!! is entirely closed, the fan spray spread is at a maximum.

In an actual test of a construction embodying the invention, utilizing a fan slot 5I approximately long held approximately from a spray surface, and utilizing an air dry enamel as the coating fluid under pressure of 30 pounds per square inch and an atomizing air pressure of 35 pounds per square inch, with the needle valve 20 closed, the maximum effective fan spread width was approximately 151/2". With the needle valve 20 fully openedgunder the same pressure conditions, the minimum effective fan spread was approximately 1%" to 2". In other words, a reduction in width ranging from approximately 1A; to almost 1%; the maximum fan spread width is possible.

Under similar` conditions and with the same spray gun, nozzles having angular disposition of the jet directions above the critical range of 1 to 10 specified herein are found to provide much less possible reduction. For example, in one device tested under similar conditions of pressure wherein the angular disposition of the jets was approximately 45, the maximum effective fan spread was found to be approximately 12 M1" and the minimum fan spread was found to be approximately 6%". In other words, the maximum reduction in width effected was less than 1A; the maximum fan spread.

When the direction of the jets from

passages

52, 53 lie below 1, the device it has been found becomes substantially inoperative with valve 20 opened because of cut-ofi effects produced by the oppositely directed jets of air under high pressure from the

passageways

52, 53. Any angular disposition of the

jet passages

52 and 53 of more than 10 with a plane normal to the longitudinal axis of the nozzle results in insuiiicient narrowing effects upon the fan spread.

When the trigger I6 is released by the operator, in the spray gun shown, coating uid cut-off occurs with the immediate closing of needle valve 31. This occurs prior to air cut-oi effected by the later closing of the air valve I4. As a result the air or gas jets from

passageways

52 and 53 as well as the atomizing air or gas jet emerging from the fan slot 5I continue momentarily after cessation of fluid flow and serve to blow out and whip oii residual coating fluid material about the fan slot 5I and the fluid tip nose 34. Likewise, the earlier cut-off of the coating fluid prevents drip. The device is thus largely self-cleaning.

The respective parts of the spray gun and particularly the fluid tip 33 and the nozzle 42 are made of metal or other suitable substances which may be machined and tooled to precise dimensions for the purposes of securing effective fan spread control and to have sharp outside edges to prevent accumulation of fluid and to assist in the self-cleaning actions described.

While a specic embodiment of the invention has been disclosed, variations in structural detail are possible and are contemplated within the scope of the claims. There is no intention, therefore, of limitation to the exact details shown and described.

What is claimed is:

1. A spray head including a discharge passage with an outlet end in said head, a fan slot extending from said outlet end and opening to the outside of said head for ejecting a fan spray, and fluid passageways having outlet ends positioned in the opposed end walls of said slot so that their axes are oppositely inclined at angles limited to from about 1 to 10 to a plane perpendicular to the axis of said discharge passages outlet end, and intersect beyond the latter, said uid passageways being adapted to be supplied with fluid under pressure for restricting the width of said spray.

2. A spray head as defined by claim 1 with said discharge passage cylindrical in shape and extending partially into said fan slot and of greater diameter than the latters width, said opposed end walls of said -fan V:510i: aringzarcuately fromsaid REFERENCES :CITED .discharge passages outletendwithv-va. radius pro- The following references me. of record `in the portioned respecting the iatters diameter to make A said opposed end walls `overlmng ysaid .outlet end me of this patent sumciently to aocommodateosaiduidpassage- 5 UNITED V)S'IAZIES PATENTS ways outlet ends positioned as defined. Number Name Date 2,172,193 'Downs Sept. 5, 11939 HOWARD WARREN BEACHf JR- 12,214,035 'Traey Sept, 10I 1940 *52,228,226 -Downs Jan. 7, 1941