US3317138A - Electrostatic spraying apparatus - Google Patents

Description

May 2, 1967 R. P. FRASER 3,317,138

ELECTROSTATI C SPRAYING APPARATUS Filed Feb. 24, 1964 6 Sheets-Sheet 1 COATING MA TEQIAL May 2, 1967 R. P. FRASER 3,317,138

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R. P. FRASER May 2, 1967 6 Sheets-Sheet 6 Filed Feb. 24, 1964 L mm J f I I I I I I I I I I f I l\ I I Al Eq I A Eq L United States Patent 63 16 Claims. (Cl. 239-1s This application is a continuation-in-part of US. application Ser. No. 285,470, filed June 4, 1963, now Patent No. 3,233,831 granted Feb. 8, 1966.

This invention relates to spraying apparatus and more particularly to such apparatus for producing a spray of electrostatically charged material.

There has been developed a portable electrostatic spraying apparatus which is rapid in action and highly efficient. One such apparatus is disclosed, for example, in the above identified application Ser. No. 285,470. Apparatus of this type customarily employs a first nozzle through which paint or other spraying material is discharged and a second nozzle supplied with fluid under pressure. The pressurized fluid is discharged from the second nozzle in a helical or vortical pattern and atomizes the material emanating from the first nozzle to form the spray. The particles of material are charged to a high electrical potential and are carried along in the spray toward the object being coated through the action of an electrostatic field.

In the use of electrostatic spraying apparatus, it is often desirable to change from one spray pattern to another while the apparatus is.in operation, and prior spraying apparatus often proved deficient in this respect. example, when coating large exterior surfaces it is advantageous to use a Wide angle spray, while for smaller objects or in cases in which material is to be applied to the interior of a hollow body it is desirable to employ a narrow angle spray. In addition, in many types of electrostatic spraying apparatus used heretofore, difficulties have been encountered in providing the optimum particle size and spray velocity for a given coating operation.

One general object of this invention, therefore, is to provide a new and improved apparatus for producing a spray of electrostatically charged material.

More specifically, it is an object of this invention to provide such apparatus in which the spray is readily adjustable from one spray pattern to another while the apparatus is in operation.

Another object of this invention is to provide apparatus of the character indicated which is capable of producing both a low velocity wide angle spray and a high velocity narrow angle spray.

A further object of the invention is to provide electrostatic spraying apparatus in which the spraying material is discharge either as a substantially axial stream, a vortical stream or a combination of the two.

A still further object of the invention is to provide electrostatic spraying apparatus which is economical to manufacture and thoroughly reliable in ope-ration.

In one illustrative embodiment of the invention, the spraying material is discharged through a first nozzle, while air or other pressurized fluid is discharged into the path of the spraying material from an annular second nozzle. The first nozzle serves as an electrode which is supplied with a high DC. potential to electrostatically charge the particles of material. The material and the fluid are fed to nozzles along a plurality of flow paths defined by unique conduit means. The flow path for the fluid is arranged to impart a particular movement thereto such that, upon contact between the fluid and For.

3,317,138 Patented May 2, 1967 ice the spraying material, the material is directed in accordance with the desired pattern.

In accordance with one feature of certain particularly advantageous embodiments of the invention, the flow path of the pressurized fluid is readily adjustable to change from one spray pattern to another while the apparatus is in operation. The type of spray is determined by the operator of the apparatus to produce a pattern which is best suited for the particular object being sprayed.

In accordance with another feature of the invention, in several good arrangements, there are provided a pair of flow paths for the pressurized fluid. One of the flow paths is arranged to produce a vertical fluid stream, while the other path produces a substantially axial stream. The relative flow of fluid along these paths is controlled in a rapid and straightforward manner such that the spraying material discharged from the first nozzle contacts the fluid stream to form either a vortical spray pattern, a substantially axial spray pattern or a combination of the two.

In accordance with still another feature of the invention, in some embodiments, the flow of pressurized fluid is adjustable to produce either a low velocity wide angle spray pattern or a high velocity narrow angle spray pattern. Should it be desired to spray, say, a tubular object, the operator employs the low velocity wide angle pattern to coat the external surfaces of the object and then adjusts the apparatus to produce the high velocity narrow angle pattern for coating the internal surfaces. This adjustment is quickly and easily accomplished without any interruption in the ope-ration of the apparatus.

The present invention, as well as further objects and features thereof, will be understood more clearly and fully from the following description of certain preferred embodiments, when read with reference to the accompanying drawings, in which:

FIGURE 1 is a partially schematic diametric sectional 'view of a portion of an electrostatic spraying apparatus in accordance with one illustrative embodiment of the invention, with the parts adjusted to produce a low velocity wide angle spray;

FIGURE 2 is a diametric sectional view, partially broken away, of portions of the apparatus shown in FIG- URE 1 with the parts adjusted to produce a'high velocity narrow angle spray;

FIGURE 3 is an enlarged elevational view, partially broken away, of a hand spray gun including the apparatus of FIGURES 1 and 2; and

FIGURES 4, 5 and 6 are partially schematic diametric sectional views in general similar to FIGURE 1 but showing electrostatic spraying apparatus in accordance with three further embodiments of the invention.

Referring to the drawings, and particularly to FIG- URES l and 2, the apparatus comprises an outer body member or housing 1 of insulating material which is generally in the form of a hollow cylinder. The forward end of the body member 1 (the right end, as viewed in FIGURES 1 and 2) is provided with a dielectric nozzle head 2 which is secured to the body member by a retaining ring 3. The body member includes screw threads 4 adjacent its forward peripheral edge to hold the ring in place.

The outer body member 1 is mounted for limited axial sliding movement on a cylindrical inner body member 5, also of insulating material. The member 5 includes an axial conduit 7 having a tubular electrode 11 therein adjacent the forwardly directed portion 6 of the member 5. The electrode 11 is fabricated from semi-conductive material having high electrical resistivity, and the forward end of the electrode serves as a nozzle for the coating material in a manner that will become more fully apparent hereinafter. The adjacent end of the portion 6 and the surrounding cap 2 form a nozzle for the pressurized fluid and are spaced apart to define an annular orifice 26. This opening is adjustable by means of a shim 27 located behind the cap 2.

An elongated, reciprocably movable pintle 8 is positioned within the passage 7. The pintle 8 extends through the electrode 11, and its forward end is provided with a conically flared head 9 which seats against a diverging surface 10 at the adjacent end of the electrode. The pintle 8 includes a plurality of radially extending fins 12 intermediate its ends which engage the inner wall of the electrode 11 and serve to maintain the pintle coaxially positioned therein. The rearwardly directed end of the pintle is connected to an operating rod 25 which is effective to move the pintle in an axial direction and thereby lift the conical head 9 oif its seat 10.

The non-conductive body member 5 includes a high tension conductor 15. This conductor extends in a direction parallel to the longitudinal axis of the apparatus and terminates in a member 16 of high resistivity material. The member 16 is held in place by an electrically conductive locking pin 16a in engagement with the electrode 11. The electrode 11 is charged to a high negative potential from a DC. source 15a through a path which extends from the negative terminal of the source, along the conductor 15, through the member 16 and then along the pin 16a to the electrode.

The inner body member 5 also is provided with a longitudinally extending conduit 13 which is supplied with compressed air or other pressurized fluid. The forward end of this conduit communicates with :an annular chamber 14 between the inner member 5 and the outer body member 1. A ring-shaped member 19 of insulating material is afiixed to the member 5 adjacent the nozzle cap 2. The member 19 defines the front wall of the chamber 14 and includes a series of swirl slots 19a, only a portion of one of the slots 19a being visible in FIG- URES 1 and 2. Each of these slots extends through the member 19 at an angle with respect to the longitudinal axis of the apparatus. The outer peripheral surface of the member 19 forms an inclined face 17 which mates with a corresponding seat 18 on the adjacent inner portion of the body member 1. The member 19 is held in place on the portion 6 of the 'body member 5 by a locking ring 20 of dielectric material.

The surfaces 17 and 18 form a valve which is movable between a closed (FIGURE 1) position and an open (FIGURE 2) position in response to axial movement of the outer body member 1 relative to the inner body member 5. In the closed position of this valve, the air or other pressurized fluid in the passage 13 is admitted to the annular nozzle opening 26 along a first path which extends through the angularly oriented swirl slots 19a. In the open position of the valve, however, the air is led to the nozzle opening 26 along a second path between the surfaces 17 and 18.

The rearwardly directed end of the outer body memher 1 is disposed within a sleeve 21 fixedly secured thereto. This sleeve is arranged to slide over the enlarged rearward portion of the inner body member 5 to permit limited movement of the outer body member relative to the inner body member. Upon movement of the sleeve in a rearward direction, for example, the outer member 1 and its attached nozzle cap 2 are similarly moved relative to the inner member 5 to open the valve formed by the surfaces 17 and 18 and to reduce the size of the nozzle opening 26. The amount of this relative movement, and hence the size of the opening 26 and the annular space between the surfaces 17 and 18 when the valve is in its open position, is determined by the space 22 between the rear end of the outer member 1 and a shoulder 23 on the facing portion of the inner member 5. If desired, the maximum axial dimension of the space 22 may be adjusted by means of a shim 24 and in practice may be of the order of one millimeter or less.

The operation of the apparatus will now be described. When the various parts are in the positions shown in FIGURE 1, the valve surfaces 17 and 18 are in engagement and therefore a gaseous fluid such as compressed air fed through the passage 13 to the annular chamber 14 passes along a path through the inclined swirl slots 19a in the member 19. These slots produce rotation of the air to form a vortex which issues from the annular nozzle opening 26. The main air pressure drop is across the inclined swirl slots 19a, and the orientation of these slots in such that the axial component of velocity is relatively low and the vortical velocity relatively high. At the same time, liquid coating material, such as paint, for example, is fed under pressure into the passage 7. Upon the movement of the operating rod 25 to the right from the position shown in FIGURE 1, the head 9 of the pintle 8 is spaced from the conical recess 10 to permit the liquid to issue from the nozzle orifice in the form of a thin divergent conical sheet. This sheet is coaxial with the axis of the air vortex and is distributed in the vortex which atomizes the liquid in accordance with a predetermined spray pattern. This pattern is such that the liquid is discharged in a low velocity wide angle spray. In several advantageous embodiments, the spray angle 0 lies within the range of from seventy degrees to one hundred and forty degrees and in the illustrated embodiment is about ninety degrees. In these embodiments, the velocity of the spray, measured at a distance of about one and one-half feet in front of the nozzle, is less than ten feet per second for best results.

The coating material is electrostatically charged to a high DC. potential during its movement through the high resistivity tube 11. As the spray is discharged from the nozzle, an electric field is established which produces an attraction between the individual spray particles and the object being coated. The arrangement is such that a smooth and uniform coating is formed on the article with minimum wastage of the coating material.

When the apparatus is adjusted to the position shown in FIGURE 2 by sliding the outer body member 1 to the left, as viewed in this figure, relative to the inner body member 5, the valve surfaces 17 and 18 are separated so that the compressed air passing through the chamber 14 now bypasses the path formed by the inclined swirl slots 19a and moves along the path defined by the surfaces 17 and 18. The thus directed air issues from the narrower annular nozzle orifice 26 as a high velocity non-vortical stream which initially converges toward the axis of the apparatus. In this mode of operation, there is a comparatively slight pressure drop as the air passes through the gap between the surfaces 17 and 18 and a high pressure drop as it passes through the orifice 26. The coating liquid issues from around the conical head 9 of the pintle 8 in the manner previously described. The liquid is discharged as an electrostatically charged divergent film into the high velocity air stream from the orifice 26 and at substantially ninety degrees to it. The resulting atomization of the liquid forms a comparatively high velocity narrow angle spray pattern. In certain particularly good arrangements, the mean velocity of the spray exceeds forty feet per second at a distance of approximately one and one-half feet in front of the nozzle, and the angle 0 of spray ranges between seventeen degrees and forty degrees.

It will thus be seen that the apparatus operates to produce two different spray patterns with two defined ranges of velocity and anglesof projection of the particles of coating material. When the apparatus is operating in the manner described with reference to FIGURE 2, the mass of fluid relative to coating material is reduced, and the drop size of the atomized particles is increased. The increased velocity and increased mass of the particles gives them a greater momentum and enables them to have a greater penetrating effect which is particularly suitable for spraying small objects or the interior of hollow bodies, for example. The smaller drop size of the wide angle low velocity spray which is produced when the apparatus is operating in the manner shown in FIGURE 1 is more suitable for coating external surfaces, particularly those of comparatively large articles.

Where the apparatus is constructed as a portable hand spray gun, as shown in FIGURE 3, it is preferably provided with two hand grips 28 and 29. The grip 28 is the normal butt of the gun and in some respects is similar to that disclosed in US. application Ser. No. 285,470 referred to above. The other grip 29 is spaced forwardly of the grip "28 and is attached to the sleeve 21. Movement of the grips 28 and 29 toward and away from each other causes slight axial movement of the sleeve 21 and hence of the outer body member 1 relative to the inner body member 5 to alter the spray pattern of the apparatus. The butt of the gun carries a finger operated trigger 30 which controls the supply of compressed air and coating material to the gun and also the switching of the high D.C. potential.

FIGURE 4 shows a further embodiment of spraying apparatus wherein parts corresponding to generally similar parts in the previously described embodiment bear the same reference numerals followed by a prime suffix. In the FIGURE 4 arrangement, the inner body member 5 is somewhat shorter than the body member 5 of FIGURES l and 2 and is provided at' 'its forward end (the right end, as viewed in FIGURE 4) with an annular nozzle member 31 of high resistivity material. The nozzle 31 is reciprocably supported with respect to the body member 5 and includes an axial conduit 7' which is flared at its forward end toform a conical surface This surface mateswith the head 9' of a pintle 8 slidably positioned in theconduit 7'. The rearwardly extending end of the conduit 7' is of reduced diameter and passes through the adjacent end wall of the member 31. A plurality of passages 31a are provided in this endwall and extend in directions substantially parallel to the conduit .7. a

The rear end of the pintle 8 projects through the conduit 7 into an enlarged cavity formed in the facing portion of the body member 5. This end of the pintle 8 is provided with a coil spring 32 which normally maintains the pintle head 9 against its seat 10'. One end of the spring 32 is affixed to the rear end of the pintle, while the other end bears against the rearward face of the nozzle member 31 to bias the pintle toward its closed position.

The inner body, member 5' is fixedly secured to the outer body member 1', and this latter body member includes a longitudinally extending conduit 13 which is supplied with compressed air.. The compressed air fed through the conduit 13' flows through one or more orifices 33 between-the annular nozzle cap 2' and the retaining ring 3. The axis of each of these orifices is tangent to the inner peripheral surface of the cap 2'. The compressed air moving through each orifice is introduced into an annular cavity 34 formed between this surface and the nozzle member 31 to produce a vortex which issues from the annular nozzle opening 26.

The liquid coating material is introduced via a tube 36 of rubber or other non-conductive flexible material into the interior of a flexible bellows-like member 35. The tube 36 is mounted in a longitudinally extending passage therefor in the inner body member 5', and the forward end of the tube extends through a radially disposed plate 35a formingthe rear end of the member 35. The member 35 encloses the adjacent end of the pintle 8' and the coil spring 32, and the end of the member opposite that including the plate 35a is in fixed relationship with the member 31. The interior of the member 35 communicates with the conduit 7' through the passages 31a. A high D.C. voltage is applied to the nozzle member 31 from a high tension cable 15', a series of resistors 37 and a helical connector member 38.

The movement of the pintle 8 and the nozzle member 31 is controlled by an axially disposed operating rod 25' which isarranged to bear against the plate 35a of the bellows member 35. To initiate the coating operation, the operating rod 25' is moved toward the right from the position shown in FIGURE 4 to contact the plate 35a. This plate in turn bears against the pintle 8' to displace the conical head 9' from the valve seating 10'. The liquid coating material within the member 35 thereupon flows under pressure along a path which extends through the openings 31a in'the adjacent end of the member 31, along the axial passage 7 and through the annular orifice around the head of the pintle. The material is electrostatically charged to a high D.C. potential as it emerges from this orifice. Simultaneously with the discharge of the material, the vortical air stream produced in the cavity 34 issues from the annular nozzle orifice 26'. The liquid is discharged as a thin divergent conical sheet which is distributed in the air vortex to atomize the liquid and produce a comparatively low velocity wide angle spray pattern.

Further movement of the operating rod 25 in the forward direction serves to increase the compression of the coil spring 32 until the forces exerted by the spring on the nozzle member 31 exceed the frictional forces tending to restrain relative movement between the nozzle member and the adjacent cap 2'. The nozzle member 31 is thereupon carried toward the cap 2' until it abuts a shoulder 2a on the cap, thereby decreasing the size of the annular nozzle opening 26'. The spacing between the shoulder 2a and the forward end of the cap 2' is such that the thus adjusted opening 26 produces a more directed atomized spray pattern having a considerably higher velocity and a narrower spray angle.

FIGURE 5 is illustrative of a further embodiment in which the size of the nozzle opening for the pressurized fluid remains constant but which is otherwise generally constructed in a manner similar in several respects to the embodiment of FIGURE 4. As in the FIGURE 4 embodiment, the spraying operation of FIGURE 5 is initiated by movement of the operating rod 25' toward the right, as viewed in FIGURE 5, to bring the rod into engagement with the rear surface of the pintle 8' through the plate 35a. The pressurized fluid within the flexible member 35 flows through the conduits 31a and the axial passage 7" inthe conductive nozzle member 31'' between the pintle head 9" and the flared surface 10". The nozzle member 31" is suitably staked to the nozzle cap 2' to prevent relative movement therebetween.

In the FIGURE 5 embodiment, the outer body member 1" is provided With two longitudinally extending air passages 13 and 39. The passage 13" is arranged to feed compressed air or other pressurized fluid through the tangential orifices 33 between the cap :2 and the ring 3' to produce a vortex emanating from the nozzle opening 26" in a manner similar to that described heretofore. The passage 39, however, communicates with an enlarged annular chamber 40 formed in the outer peripheral surface of the nozzle member 31". The chamber 40 is connected to the annular cavity 34 by longitudinally extending passages 41.

In cases in which it is desired to produce a low velocity wide angle spray pattern, air is fed to the nozzle orifice 26" along a flow path which extends from. the passage 13", through the tangential openings 33 and then to the cavity 34 leading to the orifice 26". The sheet of air discharged from this orifice intersects the stream of coating material discharged from the passage 7" to atomize the material and form a low velocity wide angle spray.

When it is desired to produce a high velocity narrow angle spray, the supply of air is transferred to the el0ngated conduit 39 while the apparatus is in operation.

This latter air follows a flow path from the conduit 39, the chamber 40 and the passages 41 to the cavity 3 4. The air is discharged from the annular orifice 26" in a nonwortical stream which contacts the coating material to form the high velocity narrow angle spray. In addition, in several good arrangements, the air is simultaneously introduced into both the cavity 39 and the cavity 13". The air from the cavity 39" introduces a nonvortical component into the air stream to provide a pattern having an intermediate velocity and spray angle. Where the apparatus is constructed as a hand spray gun, for example, the valves for controlling the admission of air through the passages 13" and 39 illustratively are operated from the butt of the gun.

In several advantageous embodiments, the apparatus is constructed in a manner similar to that shown in FIGURE 5, but the pintle 3' and the operating rod 25 are eliminated, together with the passage for the flexible tube 36 in the inner body member 5. Thus, as shown in FIGURE 6, for example, an inner body member 5" is substituted for the body member 5' of FIG- URE 5 and is provided with an axial flexible tube 36' for the coating material. The material is fed from the tube 36' through the plate 35a into the bellows-like member 35. The material then passes through the conduit 7" in the nozzle member 31" and out the flared orifice at the forward end of this conduit. The pressurized fluid is led to the orifice 26' in a manner generally similar to that described above with respect to the FIGURE 5 embodiment to produce either a wide angle low velocity spray pattern or a narrow angle high velocity pattern.

In the various illustrated embodiments of the invention, the change between the different spray patterns is accomplished in a rapid and straightforward manner while the apparatus is in operation to provide adjustable spray patterns which may be varied in accordance with the various types of objects being coated. The deposition of the coating material on the object is further facilitated by the electrostatic attraction established between the object and the individual particles of material. The generally hemispherical shape of .the forward end of the apparatus enhances the disposition of the electrostatic field and further improves the coating action.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. Electrostatic spraying apparatus comprising, in combination, nozzle means defining a discharge orifice conduit, means for directing spraying material and fluid under pressure to said nozzle means along a plurality of paths, said conduit means including an axially slidable portion for changing the flow of said fluid from one of said paths to the other, said spraying material being discharged from said discharge orifice and being contacted by said fluid to produce both a wide angle spray pattern and a narrow angle spray pattern, a voltage source, means for supplying voltage from said source to said nozzle means, to electrostatically charge the particles of spraying material directed through said orifice, and means operatively associated with said conduit means for adjusting said axially slidable portion, to change the discharge of said material from one of said spray patterns to the other.

2. In a portable electrostatic spray gun, in combination, nozzle means defining a discharge orifice, conduit means for directing spraying material and fluid under pressure to said nozzle means along a plurality of paths, said conduit means including an axially slidable portion for changing the flow of said fluid from one of said paths to the other, said spraying material being discharged from said discharge orifice and being contacted by said fluid to produce both a low velocity wide angle spray pattern and a high velocity narrow angle spray pattern, a source of high DC. voltage, means for supplying voltage from said source to said nozzle means, to electrostatically charge the particles of spraying material directed through said orifice, and means operable during the discharge of spraying material through said orifice for adjusting the axially slidable portion of said conduit means, to change the discharge of said material from one of said spray patterns to the other.

3. In a portable electrostatic spray .gun, in combination, nozzle means defining a plurality of discharge orifices, conduit means for directing particles of spraying material and pressurized fluid to said nozzle means and respectively through said orifices, the spraying material being discharged into a stream of said fluid, adjustment means cooperating with said conduit means for modifying the same to vary the flow of said fluid through the corresponding orifice to produce both a vortical spray pattern and a spray pattern in which the individual particles of spraying material are discharged along substantially linear paths, a voltage source, means for supplying voltage from said source to said nozzle means, to electrostatically charge said spraying material, and means operatively associated with said conduit means for adjust ing said adjustment means, to change the path of said spraying material from one of said spray patterns to the other.

4. Electrostatic spraying apparatus comprising, in combination, means defining first and second discharge nozzles in juxtaposed relationship with each other, conduit means for respectively directing spraying material and pressurized fluid to said first and second discharge nozzles along a plurality of paths, said conduit means including an axially slidable portion for changing the flow of said fluid from one of said paths to the other, the spraying material being discharged from said first discharge nozzle and being contacted by the fluid discharged from said second nozzle to produce both a wide angle spray pattern and a narrow angle spray pattern, a source of high DC. voltage, means for supplying voltage from said source to said first discharge nozzle, to electrostatically charge the particles of spraying material directed therethrough, and means operable during the discharge of spraying material through said first nozzle for adjusting the axially slidable portion of said conduit means, to change the path of said spraying material from one of said spray patterns to the other.

5. Electrotatic spraying apparatus of the character set forth in claim 4, in which said first discharge nozzle comprises an electrode of tubular configuration electrically connected to said voltage source.

6. Electrostatic spraying apparatus comprising, in combination, means defining first and second discharge nozzles in juxtaposed relationship with each other, conduit means for respectively directing spraying material and pressurized fluid through said first and second discharge nozzles, the spraying material being discharge-d into a stream of said fluid, adjustment means cooperating with said conduit means for modifying the same to vary the flow of said fluid through said second discharge nozzle to produce both a vortical spray pattern and a substantially axial spray pattern, a source of high DC. voltage, means for supplying voltage from said source to said first discharge nozzle, to electrostatically charge the particles of spraying material directed therethrough, and means operatively associated with said conduit means for adjusting said adjustment means, to change the path of said material from said vortical spray pattern to said substantially axial spray pattern.

7. Electrostatic spraying apparatus comprising, in combination, means defining first and second discharge nozzles in coaxial relationship with each other, conduit means including a plurality of spraying material and pressurized fluid to said first and second discharge nozzles, respectively, said conduit means having means forming a first portion of the flow path for said pressurized fluid for imparting a vortical movement thereto and having means forming a second portion of the flow path for said pressurized fluid for imparting a substantially axial movement thereto, the pressurized fluid discharged from said second nozzle acting on the spraying material discharged from said first nozzle, adjustment means cooperating with said conduit means for controlling the flow of fluid along said first portion and said second portion to produce both a vortical spray pattern and a substantially axial spray pattern, a source of high D.C. voltage, means connected between said source and said first discharge nozzle for applying said voltage to the spraying material discharged therefrom, and means operable during the discharge of spraying material throughsaid first nozzle for adjusting said adjustment means to change the flow of fluid through said conduit means from said first flow path portion to said second flow path portion, to thereby change the spray pattern of said material from said vortical pattern to said substantially axial pattern.

8. Electrostatic spraying apparatus comprising, in combination, means defining first and second discharge nozzles in coaxial relationship with each other, conduit means including first, second and thrid flow paths for supplying spraying material and pressurized fluid to said first and second discharge nozzles, said spraying material being led to said first discharge nozzle over the first of said flow paths and said pressurized fluid being led to said second nozzle over one of said second flow path and said third flow path, said conduit means having means forming a portion of said second flow path for imparting a vortical movement to the fluid discharged from said second nozzle and having means forming a portion of said third flow path for imparting a substantially nonvortical movement to the fluid discharged from said second nozzle, said fluid acting on the spraying material discharged from said first nozzle to produce a vortical spray pattern in response to movement of said fluid along said second flow path and acting on the discharge material to produce a substantially nonvortical spray pattern in response to movement of the fluid along said third flow path, a source of high D.C. voltage, means connected between said source and said first discharge nozzle for applying said voltage to the spraying material discharged therefrom, and means operable during the discharge of spraying material through said first nozzle for changing the flow of fluid to said second nozzle from said second flow path to said third flow path, to thereby change the spray pattern of said material.

9. Electrostatic spraying apparatus of the character set forth in claim 8, in combination, said conduit means including an elongated pintle disposed along said first flow path and having an enlarged end portion in position to block the flow of coating material through said first discharge nozzle, and means for moving said pintle relative to said first nozzle to control the flow of material therethrough.

10. Electrostatic spraying apparatus comprising, in combination, an inner body member of generally tubular configuration defining a first discharge nozzle, a cylindrical outer body member coaxially supported around said inner body member for movement with respect thereto between two positions, a portion of said outer body member being spaced from said inner body member to define a second discharge nozzle, conduit means including a plurality of flow paths for supplying spraying material and pressurized fluid to said first and second discharge nozzles, respectively, said conduit means having means forming a first portion of the flow path for said pressurized fluid for imparting a vortical movement thereto when said outer body member is in one of its positions flow paths for supplying and having means forming a second portion of the flow path for said pressurized fluid for imparting a substantially non-vortical movement thereto when said outer body member is in the other of its positions, the pressurized fluid discharged from said second nozzle acting on the spraying material discharged from said first nozzle to produce two diflerent spray patterns determined by the relative positions between said body members, a source of high D.C. voltage, means connected between said source and said first discharge nozzle for applying said voltage to the spraying material discharged therefrom, and means operable during the discharge of spraying material through said first nozzle for moving said outer body member from said one position to said other position relative to said inner body member to change the spray pattern of said material.

11. Electrostatic spraying apparatus of the character set forth in claim 10, in combination, one of said spray patterns comprising a low velocity wide angle spray, and the other of said spray patterns comprising a high velocity narrow angle spray.

12. Electrostatic spraying apparatus of the character set forth in claim 11, in combination, said wide angle spray lying within the range of from about seventy degrees to about one hundred and forty degrees, and said narrow angle spray lying within the range of from about seventeen degrees and about forty degrees.

13. Electrostatic spraying apparatus comprising, in combination, an inner body member including a tubular electrode defining a first discharge nozzle, a cylindrical outer body member coaxially supported around said inner body member for movement with respect thereto between two relative positions, a portion of said outer body member being spaced from said inner body member to define a second discharge nozzle, conduit means in at least one of said body members including a plurality of flow paths for supplying spraying material and pressurized fluid to said discharge nozzles, respectively, said conduit means having means forming a first portion of the flow path for said pressurized fluid for imparting a vortical movement thereto when said outer body member is in one of its positions and having means forming a second portion of the flow path for said pressurized fluid for imparting a substantially non-vortical movement thereto when said outer body member is in the other of its positions or a substantially non-vortical spray pattern, a source of high D.C. voltage, means connected between said source and said tubular electrode for applying said voltage to the material discharged from said first nozzle, and means operable during the discharge of spraying material through said first nozzle for moving said outer body member relative to said inner body member from said one position to said other position, to change the flow of fluid through said second nozzle from said vortical movement to said substantially non-vortical movement.

14. Electrostatic spraying apparatus comprising, in combination, an inner body member of generally tubular configuration defining a first discharge nozzle, a cylindrical outer body member coaxially supported around said inner body member for movement with respect thereto, a portion of said outer body member being spaced from said inner body member to define a second discharge nozzle, conduit rneans in at least one of said body members including first, second and third flow paths for supplying spraying material and pressurized fluid to said first and second discharge nozzles, said spraying material being led to said first discharge nozzle over the first of said flow paths and said pressurized fluid being led to said second nozzle over one of said second flow path and said third flow path, said conduit means having means forming a portion of said second flow path for imparting a wide angle spray pattern to the fluid discharged from said second nozzle and having means forming a portion of said third flow path for imparting a narrow angle spray pattern to the fluid discharged from said second nozzle, said wide angle spray pattern lying within the range of from about seventy degrees to about one hundred and forty degrees and said narrow angle spray pattern lying within the range of from about seventeen degrees and about forty degrees, a source of high DC. voltage, means connected between said source and said first discharge nozzle for applying said voltage to the spraying material discharged therefrom, and means operable during the discharge of spraying material through said first nozzle for moving said outer body member relative to said inner body member to change the flow of material from one of said pair of flow paths to the other, to thereby change the spray pattern of said material.

15. Electrostatic spraying apparatus of the character set forth in claim 14, in combination, the velocity of the wide angle spray being less than about ten feet per second, when measured at a distance of about one and onehalf feet from said first discharge nozzle, and the velocity of the narrow angle spray being in excess of about forty feet per second, when measured at said distance.

16. Electrostatic spraying apparatus of the character set forth in claim 14, in combination, said second flow path including a plurality of swirl slots for directing the 12 pressurized fluid moving therethrough along a vortica] path.

References Cited by the Examiner UNITED STATES PATENTS 1,401,880 12/1921 Connelly 239405 1,531,986 3/1925 Shelburne 239405 X 1,736,768 11/1929 Boynton 239-405 X 2,373,595 4/1945 Peeps 239406 X 2,530,206 11/1950 Neiburg 239417 X 2,574,879 11/1951 Lundber g et al 239406 2,643,916 6/1953 White et al 239-416.5 2,754,225 7/1956 Gfeller 23915 X 2,894,691 7/1959 Sedlacsik 239-15 2,904,262 9/1959 Peeps 239-408 3,000,574 9/1961 Sedlacsik 23915 3,056,557 10/1962 Walberg 23915 3,059,613 10/1962 Nakaya 23915 X 3,219,276 11/1965 Norris 23915 M. HENSON WOOD, JR., Primary Examiner. EVERETT W. KIRBY, Examiner. J. D. HUSSER, R. S. STROBEL, Assistant Examiners.

Claims (1)

1. 3. IN A PORTABLE ELECTROSTATIC SPRAY GUN, IN COMBINATION, NOZZLE MEANS DEFINING A PLURALITY OF DISCHARGE ORIFICES, CONDUIT MEANS FOR DIRECTING PARTICLES OF SPRAYING MATERIAL AND PRESSURIZED FLUID TO SAID NOZZLE MEANS AND RESPECTIVELY THROUGH SAID ORIFICES, THE SPRAYING MATERIAL BEING DISCHARGED INTO A STREAM OF SAID FLUID, ADJUSTMENT MEANS COOPERATING WITH SAID CONDUIT MEANS FOR MODIFYING THE SAME TO VARY THE FLOW OF SAID FLUID THROUGH THE CORRESPONDING ORIFICE TO PRODUCE BOTH A VORTICAL SPRAY PATTERN AND A SPRAY PATTERN IN WHICH THE INDIVIDUAL PARTICLES OF SPRAYING MATERIAL ARE DISCHARGED ALONG SUBSTANTIALLY LINEAR PATHS, A VOLTAGE SOURCE, MEANS FOR SUPPLYING VOLTAGE FROM SAID SOURCE TO SAID NOZZLE MEANS, TO ELECTRO-

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