US2504216A - Spray gun - Google Patents

Description

w. N. T. MORTON SPRAY GUN Filed Dec.

INVEN TOR. 'MAKEF/V f/faera/v I t4rraewey3 April 18, 1 950 w RN h\ E Q Q E w \w R w Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE SPRAY GUN Walter N. T. Morton, Windsor, Ontario, Canada Application December 23, 1944, Serial No. 569,446

2 Claims. .(Cl. 299-1401) This invention relates to the art of spraying liquid substance and it has to do particularly with the spraying of such substances as paint, lacquer, varnish, or shellac, or other material to be applied to the surface of any object.

For the purpose of disclosing the invention, reference will be made largely to the spraying of coating materials, such as those above mentioned, and for convenience, such materials will be referred to as paint, lacquer, or the like. However, the invention is applicable to the spraying of other substances which are to be applied to the surface for purposes other than the application of a coating of paint or lacquer or the like.

The advantage of spraying paint or lacquer or the like onto the surfaces of objects are, of course, well known to those versed in the art. Various lacquers or paints are applied to such items as automotive vehicles practically exclusively by the spraying method. The spraying method may also be used in the painting of houses or the preparation of furniture. There is, however, a serious problem which has heretofore confronted the users of spraying apparatus. This problem is the fact that much of the substance sprayed is not applied to the surface of the intended object, but floats away, so to speak, in the atmosphere in the form of finely divided particles, and for the most part, ultimately becomes deposited on surrounding objects or surfaces.

When a paint or lacquer is sprayed, the same is applied by means of an air jet or air stream, and surrounding the entire locale, a situation develops which may be described as fog. This fog comprises finely divided particles of the paint or lacquer suspended in the atmosphere in an uncontrolled manner. Where spraying is done commercially, large and expensive spray booths are provided to more or less confine this fog or vapor and considerable attention must be given to a proper ventilation in order to carry away this fog, or vapor or fumes. There is also a danger of fire or explosion where the paint or lacquer or the like is combustible. Moreover, the substance in the fog or vapor deposits all over the walls of the booths and on any other surface in the vicinity. This requires the surfaces to be cleaned and scraped from time to time with the particular view, among others, of lessoning the fire hazard.

The spraying of paint on the walls of a building, be it a residence or commercial building, has, it is believed, been deterred by reason of this condition. It has been found by experience that if the interior walls of one portion of a building are painted by the spraying method, that some of the vapors containing the finely divided paint circulate through the building, and then the substance deposits all over the place. This, of course, is extremely undesirable, not only from the standpoint of other walls in the building, but from the standpoint of getting the substance on the furniture, rugs, drapes, clothing and the like. A similar situation eXisits where an object, such as a building or a house is sprayed on its exterior in the open atmosphere. The breeze or wind carries away much of the paint and this situation can be particularly aggravated if there is a substantial wind.

The present invention has to do with a spraying device and with a method for spraying liquid substances which will overcome largely, if not entirely, the above mentioned defect and problem. In accordance with the invention, these sub- ,stances, whether it be paint or lacquer or other material, is sprayed by means of an air stream or jet substantially in the usual fashion, and the spraying stream or jet which contains the sprayed substance is confined within a zone of narrow limits and, thus the fog or fumes containing the finely divided substance is prevented from circulating or moving away from the zone of spraying. To this end, the spraying stream is surrounded, in effect, by a wall or screen through which the fog cannot penetrate. This confining wall is accomplished by the projection of an encasing or hollow stream or jet of air at a sufficiently high velocity as to prevent the paint particles in the fog or in the fumes from penetrating or passing through the same. Where the hollow stream or jet of air is projected from the instrument which sprays the paint or lacquer, the hollow stream may be of gradually enlarging size and may be visualized as a cone of high velocity air which surrounds the spraying stream. Moreover, the invention makes for a sewing and economy in the sprayed substance as the paint or lacquer, which otherwise would escape, is maintained under control and applied to the surface of the object.

One form of device for carrying out the invention is disclosed in the accompanying drawings, together with some modified forms, and in these drawings:

Fig. 1 is a cross sectional view of a spray gun equipped with means for the projection of the encasing or enclosing stream of air.

Fig. 2 is a cross sectional View taken substan tially on line 22 of Fig. 1 showing some of the air passageways.

Fig. 3 is an end view of the spray head looking in the direction of a line 3-3 of Fig. 1.

Fig. 4 is a side elevational view with parts cut away showing a modified form of the invention.

Fig. 5 is a view somewhat similar to Fig. 4 showing a further modified form.

The spray gun shown in Fig. l, is adapted to be gripped in the hand of the user and it has a handle I with an air supplying passage 2 which is to be connected to a suitable source of air for supplying air under pressure. A suitable valve controlling trigger is shown at 3, adapted to be manipulated by the finger and it is pivoted to the gun body as at 4. There is an air controlling valve 5 acted upon by a spring 8 and which has a stem 1 extending through a suitable packing gland .8 engageable with the trigger 3. The spring nor.- mally seats the valve and movement of the trigger 3 counter-clockwise, as Fig. l is viewed, causes the valve to be opened against the action of the spring. This permits the air to flow through passage 2 andpassage ll] and into passage H. From this point the air flows through port 12 in the valve housing, through port it in the body of the gun, through a circumferential groove It in a bushing l5, through a port It into passageway H, which surrounds a hollow bushing l8.

The paint, or other material to be sprayed, is supplied through. the passage 2c of a fitting 2!, which passage leads into passage 22 of a jet tube 23. The jet tube is provided with a suitable jet orifice 24, controlled by a needle valve 25, operably associated with the trigger .through the means of an enlargement .25. Within the bushing i5 is a plunger 2'! acted upon by a spring 23. This plunger engages the enlargement of the needle valve and causes the needle valve to shift to the left, as Fig. 1 is viewed to close the jet orifice. When the trigger is shifted counter-clockwise, the plunger 21 and the needle valve are retracted to open the orifice. The needle valve extends through a packing gland 30.

From the passage l! the air flows through a passage 3.5 to a circumferential chamber 35 surrounding the jet sleeve 23. The circumferential passage 36 communicates, througha ported bushing 39, with a passage 3'! which surrounds the jet orifice 24 and then air is discharged around the jet orifice through the circumferential outlet passage 38. Accordingly, it will be observed that when the trigger .ismanipulated, the paint controlling needle valve 22 is shifted to open the jet passage 24 andlthe air control valve 5 is shifted to open the air channel so that air under pressure fiows through the several passageways mentioned, and discharges through the port 38. The resultof this is, as is well known to those versed in the art, that there is a spray Ml of air containing the paint, lacquer or other substance, which is to be sprayed upon an object. The form or shape of the spray may be controlled by means of a needle valve '41 threadedinto the bushing l8 and provided with a finger piece 42. When this valve is retracted on its threads. so as, to open the passageway 33 in the bushing l8, air may flow from the passageway"surrounding the bushing 18 through one-or more ports '44. This air may then flow through passage 45 and then through ports lfiinto passages 41 where the same is discharged and directed againstthe stream 40 as at to. This control may flatten or otherwise shape the spraying stream as desired.

The wall of moving air, which may be stated as high velocity air, is illustrated at 55. Of

course, the term high velocity is a relative one, and the actual velocity may vary in accordance with the needs and desired. It need not be necessarily of higher velocity than the spraying stream 30; it may be of lower velocity or about the same velocity. In any event, the stream may also be considered a high velocity stream.

One way to obtain the surrounding or protecting wall 55 is to utilize some of the high pressure air supplied through the passage 2. Also, this may be controlled by the valve 5. There are a plurality of ports in the spray head, as shown at 60, which connect into the circumferential passage 36 and which open on the outside of the spray head. To confine and direct this air, a shield Bl, which may be of conical form is attached to. the outside of the spray head and thus forms a circumferential passage 62 for giving direction to the wall of air 55 as it is discharged from the circumferential port or opening 63-. The device 6| may be attached to the body of the gun-by screws 65 and it may sit upon abutmentsor projections 66, thus to provide slot-like passages 61 positioned just to the'rear of the location where the ports 60 communicate with the passage 52. With this arrangement, the high velocity air, which is discharged through the ports into the passage 62, draws in additional air through thepassages 61.

It will be noted that the wall of protecting air 55, as Fig. 1 is viewed, comprises a relatively thin layer of air moving at a desired relatively-high velocity, and that it is of conical form in that it gradually enlarges in a direction away from the spray gun. The spray jet 40 is thus completely surrounded by the circumscribing air screen 55. This may leave a zone of low pressure in the area within the protecting layer of air and around the spraying jet 40, but this pressure may, if necessary, be relieved by ports T0 passing through the head and communicating into the passage 62.

The form shown in Fig. 4 is similar to the one just described except that the port 63a is modified by the provision of a curved surface H on the sprayhead. Otherwise the form shown in Fig. 4 has thesame reference charactersappliedtolike parts. In Fig; 5- the directing shield is omitted and the air stream a in. this form is projected directly from one or more ports or slots in the portion 12 of the spray gun.

In use, the spray jet 40 is completely enclosed within the area: defined by the circumscribing air screen 55. Thezoneor area around the spray jet contains the fog with the finely divided particles of the sprayed substance, but this fog does not escape through the circumscribing screen of high velocity air. If one should project a finger through the air screen 55, deposits of the sprayedmattermay be visible upon the finger when retracted. When the gun is placed sufliciently close tow the object being sprayed, the 'circumscribingair stream may be played directly moon thesurface and, it can be noticed at times, that the finely divided paint or the like, which is picked up by the air stream 55, is deposited upon the surface of the object being sprayed. The surfaces of ob.- jects disposed to the outsideatmosphere, as exterior of houses, maybe sprayed ina substantial wind and yet the high velocity air stream 55 protects and-covers the spray jet and prevents 5 the finer particles from-being blown away by the wind. Since the finer particles, occurring in what we have termed fog, are confined and prevented from circulating away from the locale of the surface being sprayed, the nearby surfaces are thus protected and deposits of the sprayed material are prevented from being deposited thereon.

I claim:

1. A device for spraying a substance such as paint, or the like onto the surface of an object which comprises, a spray head, means providing a substantially centrally located discharge orifice in the head, for a spray jet of air which carries the substance, other discharge orifice means in the spray head for directing controlling jets on the spray jet, said spray head having an exterior conical wall diverging in the direction of the spray, means including ducts for supplying air under pressure to the discharge orifice means, ports leading from a duct to the outside of the spray head adjacent the conical wall thereof, and a conically shaped shield secured to the device and fitted over said head, said shield having internal walls spaced from the external walls of the head to provide a space, said ports leading into said space, the base of the conically shaped head and the base of the conically shaped shield being spaced apart to provide a substantially unbroken circumferential outlet for air flowing through said ports and said space whereby to project a jet of air of conical form surrounding the said spray jet to thereby confine airborne particles of the spray jet within the conical jet of air.

2. A device for spraying a substance such as paint, or the like onto the surface of an object which comprises, a spray head, means providing a substantially centrally located discharge orifice in the head for a spray jet of air which carries the substance, other discharge orifice means in the spray head for directing controlling jets on the spray jet, said spray head having an exterior conical shape with the walls diverging in the direction of the spray, means including ducts for supplying air under pressure to the discharge orifice means, ports leading from a duct to the outside of the spray head adjacent the conical 6 walls thereof, and a conically shaped shield secured to the device and fitted over said head, said shield having internal walls spaced from the external walls of the head to provide a space, said ports leading into said space, the base of the conically shaped head and the base of the conically shaped shield being spaced apart to provide a substantially unbroken circumferential outlet for air flowing through said ports and said space whereby to project a jet of air of conical form surrounding the said spray jet to thereby confine airborne particles of the spray jet within the conical jet of air, and ports extending through the spray head and connecting the space between the spray head and the shield, and the area between the spray jet and the conical jet of air, said extending ports alleviating the reduction of pressure between the spray jet and the jet of air of conical form.

WALTER N. T. MORTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,219,642 Isaacs Mar. 20, 1917 1,326,683 Doran Dec. 30, 1919 1,463,332 Parker et al July 31, 1923 1,523,855 Barrows Jan. 20, 1925 1,741,169 Thompson Dec. 31, 1929 1,974,538 Johnston Sept. 25, 1934 2,029,337 Parker Feb. 4, 1936 2,086,183 Gellner et a1 July 6, 1937 2,138,300 Gustafsson Nov. 29, 1938 2,247,000 Popofi June 24, 1941 2,373,595 Peeps Apr. 10, 1945 2,410,532 Tessier Nov. 5, 1946 2,438,471 Ball Mar. 23, 1948 FOREIGN PATENTS Number Country Date 229,956 Great Britain Sept. 19, 1924 366,394 Italy Dec. 26, 1938 508,719 Great Britain Jan. 25, 1938

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