US3865314A

US3865314A - Adjustable pattern spray gun

Info

Publication number: US3865314A
Application number: US443480A
Authority: US
Inventors: Gustave S Levey; Edward Moser
Original assignee: SAID LEVEY BY SAID MOSER
Current assignee: SAID LEVEY BY SAID MOSER
Priority date: 1974-02-19
Filing date: 1974-02-19
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11
Also published as: BE825690A

Abstract

A paint spray gun of the airless type is disclosed. The spray gun includes a spray tip having a non-circular, elongated sharp edged nozzle opening and also includes a chamber leading to and larger in area than the nozzle opening and a pre-orifice adjustable in area and positioned upstream from the chamber and co-axial with the nozzle opening. The disclosed pre-orifice is formed by arcuate recesses in opposed relatively movable jaws and, in its minimum area adjustment, is a non-circular elongated opening similar to the nozzle opening. Interfitting parts maintain the long dimensions of the nozzle opening and the preorifice in parallel relationship. When the area of the preorifice is adjusted to be in the range of not more than about twice to not less than about one-fourth the area of the nozzle opening, the liquid paint delivered under pressure to the gun passes from the pre-orifice through the chamber as a submerged jet and emerges from the nozzle opening to provide a uniformly atomized spray pattern with feathered edges. As the area of the pre-orifice is reduced through this range, the quantity of paint emitted is reduced without reduction of the velocity, permitting the spray pattern applied to the work to be narrowed without loss of quality or film thickness.

Description

United States Patent [1 1 Levey et al.

[ Feb. 11, 1975 ADJUSTABLE PATTERN SPRAY GUN {75] Inventors: Gustave S. Levey, 6220 Reamer,

Houston. Tex. 77036; Edward Moser. Houston. Tex.

[73] Assignee: said Levey, by said Moser (22] Filed: Feb. 19, 1974 [211 App]. No.: 443,480

[52] US. Cl 239/590.3, 239/526, 239/599 [51} Int. Cl B051) 1/04 [58] Field of Search 239/599, 597, 600, 601, 239/5903, 526, 583

[56] References Cited UNITED STATES PATENTS 3.000.576 9/1961 Levey et al. 239/597 X 3 5l5.355 (i/l970 Wagner 239/526 3.556.4ll l/l97l Nord et a] 239/599 X 3.659.787 5/1972 Ito 239/599 X Primary Examiner-M. Henson Wood, Jr. Assistant E.ramt'ner--.lohn J. Love Attorney, Agent, or Firm-McNenny, Farrington, Pearne & Gordon [57] ABSTRACT A paint spray gun of the airless type is disclosed. The

spray gun includes a spray tip having a non-circular, elongated sharp edged nozzle opening and also includes a chamber leading to and larger in area than the nozzle opening and a pre-orifice adjustable in area and positioned upstream from the chamber and coaxial with the nozzle opening. The disclosed preorifice is formed by arcuate recesses in opposed relatively movable jaws and, in its minimum area adjustment, is a non-circular elongated opening similar to the nozzle opening. lnterfitting parts maintain the long dimensions of the nozzle opening and the pre-orifice in parallel relationship. When the area of the preorifice is adjusted to be in the range of not more than about twice to not less than about one-fourth the area of the nozzle opening, the liquid paint delivered under pressure to the gun passes from the pre-orifice through the chamber as a submerged jet and emerges from the nozzle opening to provide a uniformly atomized spray pattern with feathered edges. As the area of the pre-orilice is reduced through this range. the quantity of paint emitted is reduced without reduction of the velocity, permitting the spray pattern applied to the work to be narrowed without loss of quality or film thickness.

40 Claims, 7 Drawing Figures ADJUSTABLE PATTERN SPRAY GUN BACKGROUND OF THE INVENTION This invention relates to spray guns for liquids such as paint or the like and, more particularly, to a spray gun for hydraulically atomizing the liquid to be sprayed.

In a hydraulically atomizing spray system or airless spray, the liquid is forced through a nozzle opening having sharp edges at sufficiently high velocities to provide atomization of the liquid. The nozzle opening has an elliptically shaped cross-section with sharp vertices to produce an elliptical or oval shaped spray pattern.

The advantages of airless spraying are discussed in U.S. Pat. No. 3,000,576 to Levey et al. In accordance with this prior patent, the non-uniform spray pattern having thickened portions or pigtails which had therefore characterized airless spray techniques was eliminated by the use of a restricted pre-orifice having a circular cross-section disposed upstream from the spray tip nozzle opening.

The occurrence of such non-uniform spray patterns was associated with the formation of a vena contracta upon acceleration of the liquid with a large pressure drop through the nozzle opening which prevents full atomization of the liquid at the vertices of the spray pattern. The formation ofa harmful vena contracta was eliminated by accelerating the liquid with a large pressure drop through the restricted pre-orifice to provide a submerged jet moving through the nozzle opening by its own kinetic energy at substantially the same velocity. By controlling the liquid in this manner, a substantially uniform pressure and velocity was obtained across the area of the nozzle opening, so that the liquid was uniformly atomized and distributed across the spray pattern with a uniform reduction in density or feathering at the margins of the pattern.

For purposes ofobtaining optimum atomization quality, the cross-sectional area of the pre-orifice opening should be substantially equal to the cross-sectional area of the nozzle opening of the spray tip. Satisfactory results are obtained so long as the area of the pre-orifice is not less than about one-fourth or more than about twice the area of the nozzle opening. A number of variously sized, circular pre-orifices are presently required to accommodate the full commercial range of spray tips in accordance with the teachings of the said U.S. Pat. No. 3,000,576. For use with seven different sized spray tips having nozzle areas ranging from the equivalent ofa round opening with a diameter of 0.01 l of an inch to a round opening of 0.031 of an inch, eight different circular pre-orifices are currently marketed having diameters ranging from 0.012 of an inch to 0.039 of an inch, so that each spray tip may be provided with a pre-orifice with an area substantially equal to or not exceeding twice the area of the nozzle opening. The changing of a pre-orifice may involve the disassembly of a significant portion of the spray gun and, at least, results in a considerable loss of production time.

In some paint spraying applications, particularly in construction or maintenance work, speed of application is paramount and quality of atomization may be sacrificed for the maximum fan width applied as quickly as possible. To that end, the operator may forego the use of a pre-orifice in order to obtain as wide a spray fan width as possible since it has been observed that the use of a pre-orifice will reduce the fan width and the volume delivered by as much as 10 percent to 15 percent in an designated spray tip. After the faster rough applications have been applied. the op erator will necessarily expend valuable production time inserting an appropriate pre-orifice to obtain the quality atomization required for the areas or applications in which quality is critical, and airless spraying without a pre-orifice is unsatisfactory.

SUMMARY OF THE INVENTION It has now been discovered that a non-circular preorifice having a generally elongated cross-section can be utilized in an airless spray system employing a flat fan" or elliptically shaped nozzle opening to provide a uniformly atomized spray pattern. The elongated, major cross-sectional dimensions of the pre-orifice and the nozzle opening are maintained in substantially parallel relationship. Further, a pre-orifice having an adjustable cross-sectional area is provided to permit corresponding variations in the spray fan and spray pattern of an airless spray gun.

In the illustrated embodiments, a pre-orifice assembly or capsule provides a restricted pre-orifice having a generally elliptical cross-sectional configuration. The cross-sectional area ofthe pre-orifice is adjustable, and it is defined by cooperating surfaces of relatively movable jaw members. The pre-orifice capsule includes spring means for biasing the jaw members apart and cam following arms for moving the jaw members together upon the axial advance of a camming member disposed within the spray gun. The movement of the camming memeber is controlled by an external adjustment nut mounted on the spray gun. The preorifice capsule includes an axially projecting alignment member engaging the spray tip to coaxially align the nozzle opening and the pre-orifice as well as to maintain the desired parallel relation between the major crosssectional dimensions.

The range of cross-sectional pre-orifice areas available is selected to accommodate the conventional spray tip nozzle opening sizes which vary from an area equal to that of a circle of 0.01 l of an inch in diameter to an area equal to that of a circle of 0.035 of an inch in diameter. (For purposes of convenience, the nozzle opening and pre-orifice opening crosssectional areas are hereinafter simply designated by the diameter in inches of a circle having an equal area.) More particularly, the elliptically shaped pre-orifice of the illustrated embodiment is adjustable from an equivalent area value of 0.01 l in its minimum area position to an equivalent area value of 0.035 in its maximum area position. In this manner, a single pre-orifice capsule may be adjusted to provide an optimum 111 area ratio between the pre-orifice opening and the nozzle opening for the entire range of commercially avialable spray tip sizes.

In addition to providing the optimum 1:1 area ratio, the adjustable pre-orifice also provides area ratios substantially in excess of 2:1 for most of the spray tips commonly employed to enable an operator to achieve full spray fan angle width potential in high speed rough work by simply adjusting the pre-orifice to its maximum size. Similarly, the spray fan angle may be narrowed or decreased for specific trim and finishing applications by reducing the size of the pre-orifice. In both of these cases, it it apparent that the volume delivcry and the spray pattern are adjusted without a significant loss of production time.

Thus, it has been discovered that the advantages and principles relating to the use of a circular pre-orifice in an airless spray system as disclosed in the aforementioned Levey et. al. patent can be obtained with a noncircular pre-orifice in accordance with the teachings of the subject invention. This discovery has been utilized in providing a pre-orifice having an adjustable crosssectional area which can be readily incorporated into a conventional airless spray gun to attain the advantages of using a pre-orifice while simultaneously eliminating the aforementioned prior art disadvantages of the same. Further, the provision of an adjustable preorifice in an otherwise conventional airless spray gun permits corresponding adjustments in the delivery volume and the spray pattern of the spray gun for resolving particular spraying problems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of an airless spray gun provided with adjustable pre-orifice means in accordance with the present invention;

FIG. 2 is a fragmentary, vertical section on an enlarged scale through the valve port and nozzle area portion of the spray gun shown in FIG. 1 depicting the preorifice capsule and having parts broken away for purposes of clarity;

FIG. 3 is a sectional view of an enlarged scale taken along the line 3-3 of FIG. 2 showing the jaw members in full open position;

FIG. 3a is a fragmentary elevational view on an enlarged scale showing a portion of the jaw members in a full closed position;

FIG. 4 is an exploded perspective view of the preorifice capsule viewed from the forward end of the spray gun;

FIG. 5 is a sectional view of the spray tip and preorifice capsule similar to FIG. 2 but on a greatly enlarged scale; and

FIG. 6 is a sectional view through a pre-orifice capsule showing another embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, an airless spray gun It) is shown. I

The spray gun includes a handle portion 12, a forwardly extending stock portion 14 and a spray portion 16 which is secured to the stock portion 14 by means of a bolt 18. In accordance with the present invention, an adjustable pre-orifice spray assembly 20 is fixed to the forward end of the spray portion 16.

The liquid to be sprayed is introduced into the spray gun through a combined swivel fitting and strainer holder 22 which is threadedly connected to the spray portion 16 of the gun. The fitting 22 is adapted to be connected to a source of liquid under pressure (not shown) and the liquid is delivered to the internal portions of the gun through a passageway 22a extending through the fitting.

The liquid to be sprayed may be pressurized in any conventional manner and a supply hose (not shown) leading to the fitting 22 may be branched if it is desired to use a heater in the supply line. A suitable pump and circulating system is disclosed in US. Pat. No. 3,018,968 to Levey. If no recirculation is required or desired, the fitting 22 may be connected to a single supply hose leading to a source of liquid under pressure, such as the outlet side of a pump (not shown).

The spray gun 10 also includes a pivoted trigger 24 which is fixed to the stem of a needle valve 26 for purposes of operating the spray gun. The needle valve 26 and trigger 24 are biased to a forward, non-spraying position by conventional means. The spray gun is actuated upon movement of the trigger 24 towards the handle l2 and the corresponding, following movement of the needle valve 26 in a rearward direction.

Referring to FIG. 2, the details of the forward portion of the spray gun 10 are shown. The adjustable preorifice spray assembly 20 is threadedly engaged to a cylindrical boss 16a extending from the spray portion I6 of the spray gun. The assembly 20 includes an axially fixed, cylindrical mounting sleeve 28 having an internally threaded rearward bore 30 which threadedly engages the external threads provided on the cylindrical boss 16a. The sleeve 28 has a radially, inwardly extending shoulder 32 which abuts against the forward end of the boss 16a when the sleeve 28 is tightly connected. Alternatively, the spray portion 16 and the sleeve 28 may be integrally formed.

The forward end of the sleeve 28 has an internally threaded bore 34 which engages an externally threaded nut 36. The nut 36 secures a spray tip or nozzle assembly 38 to the forward end of the spray gun 10. A sealing gasket 360 formed of a suitable seal material such as nylon or teflon is provided at the forward face of the spray tip holder. The spray tip or nozzle assembly includes a spray tip holder 39 having a flat fan" spray tip 40 mounted therein.

As previously indicated, the liquid to be sprayed is introduced into the gun by means of the fitting 22 and, more particularly, a passageway 22a extending therethrough and communicating with a central bore 42 in the spray portion 16 of the spray gun. The needle valve 26 is axially movable with the bore 42, and its movement is guided by a counterbore 44 (FIG. 1). The stem of the needle valve extends through the counterbore 44 and a gland nut 46 which seals the free, rearward end of the counterbore.

The forward end of the bore 42 is internally threaded for engagement with the rearward portion of a cylindrical nut member 48. The forward portion of the member 48 is threadedly engaged with a valve body holder 50. The cylindrical nut member 48 and the valve body holder 50 are respectively provided with communicating, coaxial internal bores 48a and 50a which in turn communicate with the central bore 42 to provide a conduit or passageway through the spray gun for delivcry of liquid to the spray tip 40.

The forward end of the bore 50a includes a reduced diameter portion having a valve body 52 press-fitted therein so that it is secured in place and sealed against fluid leakage. The valve body 52 is preferably made of a hard erosion resistant material such as tungsten carbide. The valve body 52 has a valve port 54 which provides a flared seating surface 56 adjacent the rearward end thereof for sealing, valving engagement with the rounded end of the needle valve 26.

The forward end of the valve port 54 opens into a pre-orifice capsule 58 having a coaxially extending passageway therethrough including an adjustable preorifice 60. The passageway through the pre-orifice capsule 58 communicates with the spray tip 40 for delivery thereto of the liquid to be sprayed as described in greater detail below.

Referring to FIGS. 3 through 5, the pre-orifice capsule 58 includes as its principal parts a forward capsule half member 62, a pair of relatively

movable jaw members

64 and 66, a pair of biasing springs 68 and 70, and a rearward capsule half member 72. When the preorifice capsule is assembled, the

capsule half member

62, 72 are interlocked together in an interference tit and they cooperate to contain the springs and jaw members in a fixed axial position. The springs are compressed in the assembled capsule and they resiliently urge the jaw members in opposite directions along the diameter of the pre-orifice capsule.

The member 72 has a generally cylindrical configuration including a central wall 73, a forwardly, axially extending skirt portion 74, and a rearwardly, axially extending skirt portion 75. The skirt portion 74 is divided into four arcuate sections by radially opposed slots 76a, 76b and relatively larger, radially off-set

slots

78a, 78b.

Each of the arcuate sections of the skirt portion 74 includes an internal shoulder 80 which cooperates to define an internal recess for purposes of engaging the member 62. Each of the arcuate sections also includes a reduced diameter or wall portion 82 extending to the forward surface of the wall 73. The portions 82 cooperate to define a chamber for receiving the

jaw member

64, 66 and

spring members

68, 70.

The

jaw members

64, 66 respectively include radially extending

cam following arms

84, 86 and guide

legs

85, 87. When the pre-orifice capsule is assembled, the guide legs of each of the jaw members engage adjacent portions of the other of the jaw members in sliding relationship as indicated below in greater detail. As best shown in FIG. 3, the slots 76a and 76b are dimensioned to receive the

cam following arms

84, 86 and contiguously disposed portions of the

legs

85, 87 to rotationally fix and stabilize the mounting of the jaw members within the pre-orifice capsule.

The

jaw members

64, 66 are also respectively provided with

guide arms

88 and 90. The guide arms are dimensioned to engage the reduced diameter portion 82 of an adjacent arcuate section of the skirt portion 74 when the jaw members are in a full open position as shown in FIG. 3.

The

jaw members

64, 66 are biased apart to their full open position by the

springs

68 and 70 which comprise double layer leaf springs. The springs are mounted within the pre-orifice capsule adjacent the

recesses

78a, 78b which provide clearance for accommodating the deflection of the springs upon relative movement of the jaw members toward one another. The

springs

68, 70 have an axial dimension corresponding to that of the reduced diameter portion 82 and they are entrapped within the assembled pre-orifice capsule. As shown in FIG. 3, the

springs

68, 70 work between the adjacent radially inward surfaces of the

guide arms

88, 90 and the adjacent, planar wall portions 82 of the

slots

78a, 78b to bias the jaw members apart.

The forward capsule half member 62 includes an axially extending alignment boss 94, a disc portion 96 and an axially rearward extending, centrally disposed sealing boss 98 projecting from the rearward surface of the disc portion 96 (FIG. 5). The sealing boss 98 may be integrally formed with disc portion 96 as shown or it may be provided by a press-fitted or otherwise bonded insert (not shown) received within a bore provided in the disc portion and extending beyond the rear surface thereof.

The disc portion 96 is dimensioned to be received against the shoulders and to provide an interference fit with the overlying skirt portion 74 of the member 72 in order to lock the capsule halves together when they are assembled. In the assembled condition, the disc portion 96 cooperates with the reduced diameter portion 82 and the forward face of the central wall 73 to define a chamber having the jaw members and spring members axially contained therein.

The rearwardly extending skirt portion 75 of the member 72 defines a recess 102 dimensioned to receive a forward shoulder of the valve body holder 50 (FIG. 2). The base of the recess 102 is defined by the rearward face of the central wall 73 of the member 72.

A pair ofthreaded bores 103 extend through the central wall 73 at spaced locations clear of the

springs

68, 70 and the

jaws

64, 66. The bores 103 are employed in a screw-jacking operation to separate the assembled

capsule half members

62, 72 after the pre-orifice assembly 58 has been removed from the spray gun. More particularly, screw members (not shown) are threadedly advanced through the bores 103 and against the adjacent, rearward face of the disc portion 96 to separate the capsule half members.

The forward face of the wall 73 includes a centrally located, axially projecting sealing boss 104 which cooperates with the sealing boss 98 to facilitate the provision of a fluid seal with the

jaw members

64, 66. The boss 104 surrounds the forward end of a passageway 106 which extends through the wall 73 and communicates between the valve port 54 and the adjustable preorifice 60.

Upon emerging from the passageway 106, the liquid enters the adjustable pre-orifice 60 which is defined by the overlying central portions of the

jaw members

64, 66. The jaw members are formed of a hard erosion resistant material such as tungsten carbide. As described in greater detail below, the pre-orifice 60 is coaxially disposed with respect to the passageway 106 and it remains in coaxial relationship regardless of the selected cross-sectional area of the pre-orifice. Further, the cross-sectional area of the passageway 106 is slightly greater than that of the pre-orifice when the latter is adjusted to its maximum cross-sectional area.

The central portions of the

jaw members

64, 66 respectively, include a

curved surface portion

108 and 110 and a transversely disposed

planar surface portion

112 and 114. The

planar surface portions

112, 114 are provided along the

guide legs

85, 87 as best shown in FIG. 3. Thus, the central portions of the jaw members have a generally J-shaped configuration with the curved bottom portions of the J configurations oppositely disposed from one another.

The

planar surface portions

112, 114 engage associated planar surfaces provided by the adjacent jaw member for purposes of guiding the relative movement of the jaw members toward and away from one another. The segments of the planar surface portions which are not engaged for purposes of guiding the jaw members cooperate with the

curved surface portions

108, 110 to define the adjustable pre-orifice 60 when the jaw members are positioned to define a relatively larger pre-orifice cross-sectional area.

Referring to FIG. 3a, the

jaw members

64, 66 are shown in a fully closed or minimum pre-orifice area position wherein the

curved surface portions

108, 110 completely define the pre-orifice 60. In this position, the pre-orifice cross-section has a generally elliptical configuration. The

curved surfaces

108, 110 may be provided with flats adjacent the engaging edges thereof at the extremities of the long dimension or major axis of the pre-orifice for wear purposes.

In the full open or maximum pre-orifice area position shown in FIG. 3, the pre-orifice cross-section assumes a somewhat circular configuration with substantially equal major and minor axes. ln the intermediate positions of the jaw members between full open and full closed, the pre-orifice is provided with a generally elongated, oval shaped configuration with blunted ends adjacent its major dimension. This variation in crosssectional configuration of the pre-orifice is not detrimental to the pre-orifice function and its effectiveness in providing uniform atomization of the sprayed liquid.

As indicated above, the pre-orifice 60 is coaxial with the passageway 106 and it remains in a coaxial relationship as its cross-sectional area is varied since the jaw members are arranged for corresponding radial movement in opposite directions toward and away from one another. To that end, the relative movement of the

jaw members

64, 66 is controlled by the axial positioning of a cylindrical cam member 116 (FIG. 2) provided by the adjustable pre-orifice spray assembly 20.

The cam member 116 includes a beveled cam surface 118 adjacent its forward end which is arranged to engage

camming surfaces

84a and 860 provided by the

cam following arms

84, 86 of the jaw members. The cam ;member 116 is shown in a fully retracted position in FIG. 2 with the cam surface 118 thereof in nonclosing engagement with the cam surfaces 84a, 86a of the jaw members.

The cam member 116 is driven by a drive key 120 extending through a slot 122 in the cylindrical mounting sleeve 28. The outer radial portion 120a of the drive key 120 is received within a groove 124 in an adjustment nut 126 and contained by retainer plate 154 secured to the nut 126. The adjustment nut 126 has an internally threaded bore 127 which is threadedly engaged with the axially fixed mounting sleeve 28. Accordingly, upon rotation of the nut 126, it threadedly moves relative to the sleeve 28 and correspondingly moves the cam member 116 by means of the drive key 120.

The drive key 120 is provided with a T-shaped configuration wherein the cross member thereof corresponds with the portion 120a and has an arcuate configuration. Thus, a plurality of drive keys and corresponding slots 122 are provided about the periphery of the sleeve 28 in order to assure the smooth axial movement of the cam member 116.

The actual amount of relative movement of the

jaw member

64, 66 upon rotation of the adjustment nut 126 is a function of the angle between the cam surface 118 and 84a, 86a together with the pitch of the threads 127. ln the illustrated embodiment, each of the jaw members moves a radial distance of about 0.018 inch for each full revolution of the adjustment nut.

As best shown in FIG. 5, the adjustable pre-orifice 60 opens into a passageway 128 provided in the forward capsule half member 62. The cross-sectional area of the passageway 128 is dimensioned so as to not interfere with the fluid jet emerging from the pre-orifice 60. The passageway 128 includes an enlarged portion 130 which opens into a similarly dimensioned bore 132 in the spray tip 40. The bore 132 preferably has a substantially perpendicular forward end wall 133 and opens into a relatively small diameter bore 134 which leads to the spray tip nozzle opening 136. As the liquid to be sprayed passes through the pre-orifice 60, it is accelerated with a consequent drop in pressure and emitted as a high velocity stream or jet of fluid. The passageway 128 and the bore 132 are filled with liquid, and liquid passes through the bore 134 and nozzle opening 136. The high velocity stream or jet of liquid moves coaxially out of the pre-orifice 60 and travels through the center of the passageway 128 and bore 132 as a submerged jet. The submerged jet enters and fills the bore 134 and upon passing through the nozzle opening 136 it is uniformly atomized to provide the desired oval spray pattern.

When the area of the pre-orifice 60 is equal to the area of the nozzle opening 136, the pressure of the liquid through the pre-orifice drops from the relatively high values in the valve port 54 and passageway 106. The liquid is carried through the bore 134 and the nozzle opening 136 by the velocity of the submerged fluid jet or kinetic energy thereof, with a relatively small pressure drop, rather than being driven through the nozzle opening by a high pressure-head on the upstream side of the nozzle opening. The liquid in the chamber defined by the passageway 128 and bore 132 is at a relatively low static pressure, and the submerged fluid jet travels through the center of this chamber with a relatively minimum amount of frictional resistance. The quality of atomization is optimized in this l:l area relation between the pre-orifice and nozzle opening.

The pre-orifice 60 has a sufficient axial length to stabilize the fluid jet as it is formed therein and cause it to persist as a submerged jet until it reaches and fills the bore 134 leading to the nozzle opening. It has been found that these objectives are achieved when the preorifice is provided with a minimum axial length equal to from about /2 to about 1 times its maximum crosssectional dimension. The pre-orifice may be provided with a greater relative axial length without significantly interfering with the volume of liquid or necessitating excessively high pressures.

The nozzle opening 136 has a conventional flat fan" or cat eye configuration comprising a generally elliptical cross-section with a sharp vertices adjacent the ends of its major axis. The cat eye configuration is provided by initially forming the bore 134 as a blind bore terminating in a spherically-shaped end 138. A transversely disposed V-shaped slot 140 is then cut into the spray tip so as to intersect the spherical end 138 of the bore 134. Thus, the nozzle opening 136 is provided with an elliptically-shaped or elongated cross-section having a long dimension or major axis no greater than the diameter of the bore 134 and a short dimension or minor axis equal to the minimum width of the V-slot 140.

As depicted in FIG. 5, the long dimension of the nozzle opening 136 is perpendicular to the plane of the section. Accordingly, the major dimensions of the spray fan emitted from the nozzle opening and the resulting oval shaped spray pattern are also perpendicular to the plane of the section and the spray tip holder 39 is provided with a recess 142 to accommodate the full width of the spray fan.

When the pre-orifice 60 is adjusted to a less than full open cross-sectional area, it is necessary to maintain the elongated dimension or major axis thereof is substantially parallel relationship with the elongated dimension or major axis of the nozzle opening 136. In order to assure the parallel relationship, the alignment boss 94 extending from the forward capsule half member 62 is provided with a non-circular cross-section by means of flats 144 extending along its peripheral surface. The pre-orifice capsule 58 is initially assembled with the major dimension of the pre-orifice 60 extending in a predetermined direction with respect to the non-circular configuration of the boss 94.

The boss 94 is received within a correspondingly shaped recess 146 in an insert 148. The insert 148 is press-fitted into a bore 150 in the spray tip holder 39 to prevent relative rotation therebetween. The spray tip 40 is similarly press-fitted into the holder 39 so that the major dimension of the nozzle opening 136 extends in a predetermined direction with respect to the recess 146, and in parallel relationship with respect to the major dimension of the closed position pre-orifice when the boss 94 is received within the recess 146.

The boss 94 is also provided with an axially extending slot 152 which bisects a portion of the axial extent thereof. The bore 146 is dimensioned to slightly compress the bisected portion of the boss upon insertion therein, and the slot 152 thereby serves to resiliently lock the pre-orifice capsule 58 to the spray nozzle assembly 38. A washer seal 153 is disposed about the boss 94 between the spray tip holder 39 and the central disc portion 96 of the member 62 to prevent liquid from escaping between the pre-orifice capsule and holder. The washer seal is formed of a suitable seal material such as teflon or nylon.

If an operator desires to rotate the major dimensions of the spray fan and the oval shaped spray pattern relative to the spray gun 10, it is simply necessary to loosen the nut 36 and rotate the spray nozzle assembly 38 by grasping it adjacent its forward end. Upon rotation of the spray nozzle assembly 38, the pre-orifice capsule 58 is correspondingly rotated about the forward shoulder of the valve body holder 50 and the parallel relationship between the major dimensions of the pre-orifice 60 and nozzle opening 136 is maintained. Accordingly, a conventional spray tip and nozzle assembly may be modified to provide a unitized assembly with the preorifice capsule and to assure the maintenance of the desired parallel relationship.

The range of cross-sectional pre-orifice areas through which the pre-orifice is adjustable may be selected on the basis of particular spray applications. The pre-orifice 60 is provided with a minor dimension of 0.009 inch and a major dimension of 0.035 inch when the

jaw members

64, 66 are moved to the minimum area or full closed position as shown in FIG. 3a, and the pre-orifice has an equivalent area value equal to about that of a circle of 0.01 l of an inch in diameter. When the jaw members are moved to the maximum area or full open position as shown in FIG. 2, the minor and major dimensions of the pre-orifice 60 are each equal to about 0.035 inch. and the pre-orifice has an equivalent area approximately equal to that of a circle of 0.035 of an inch in diameter.

Thus, the ratio of the cross-sectional area of the preorifice to the cross-sectional area of the nozzle opening may be varied from one-fourth to two for fine finishing spray tips and a restricted volume and modified spray pattern is obtainable for most commercially available spray tips by reducing the ratio value to about L0 or less. When the area of the pre-orifice is less than that of the nozzle opening, uniform atomization and distribution is still obtained but a lesser volume of liquid is delivered through the nozzle than would otherwise be obtained at a given liquid pressure. Although the delivered liquid volume is reduced in this instance, the liquid velocity remains the same, and the resulting spray pattern applied to work surface can be narrowed without loss of quality or film thickness by manually bringing the spray gun closer to the work surface.

If the area of the pre-orifice is reduced too much, the jet or liquid delivered to the bore 134 is insufficient to fill the same and the desired atomization is not obtainable. The critical limit is believed to be reached when the area of the pre-orifice is about V4 the area of the nozzle opening.

Ratios in excess of 2.0 are available to provide full spray angle potential for most spray tips commonly employed. It should be appreciated that uniform atomization is obtained at ratios of about 2.0 or when the preorifice area is twice that of the nozzle opening but that a compromise in atomization quality is made when the ratio exceeds 2.0 in order to obtain high volume and high speed spraying.

Referring to FIG. 6, a modified embodiment of the pre-orifice capsule is shown. For purposes of convenience, the parts of the modified embodiment have been designated with the same numbers as the corresponding parts of the embodiment shown in FIGS. 1 through 5 but for the addition of prime designations.

In FIG. 6, the pre-orifice capsule 58' includes as its major elements a forward capsule half member 62, rel atively movable jaw members 64, 66' and a rearward capsule half member 72'. As in the first embodiment, the jaw members 64, 66' cooperate to define an adjustable pre-orifice and the adjustment thereof is controlled in the same manner as described above with respect to the first embodiment.

The capsule half member 72' includes a central wall 73' which is provided with a passageway 106' extending therethrough. The wall 73' has a centrally disposed, circular recess which is sized to receive a compression disc insert 172 in sliding relationship. The disc insert 172 includes a bore 173 which is coaxial with the passageway 106.

The disc insert 172 projects beyond the forward surface of the wall 73 and into sealing engagement with the

jaw members

64, 66. The insert 172 is axially biased in a forward direction into engagement with the jaw members by means of a belleville spring 174 disposed between the insert and the bottom of the recess 170. The belleville spring has a generally circular configuration and it includes a central bore 176 extending therethrough.

The forward capsule half member 62' includes a disc portion 96 having a centrally disposed recess 178 in the rearward face thereof which communicates with a passageway 128 extending through a forward alignment member 94'. A circular insert 180 is bonded and axially fixed within the recess 178. The insert 180 has a central bore 182 which communicates between the adjustable pre-orifice 60 and the passageway 128'.

The insert 180 projects axially beyond the rearward surface of the disc portion 96' of the member 62 and into sealing engagement with the jaw members 64', 66'. Accordingly, the compression disc insert 172 and the insert 180 cooperate to engage the jaw members in a fluid sealing arrangement similar to that provided by the sealing

bosses

96 and 104. However. the provision of the fluid seal is facilitated by the use of the belleville spring 174 to bias the disc insert l72,jaw members 64', 66' and the insert 180 into sealing relationship.

While preferred embodiments of the invention have been described in considerable detail, it will be understood that various rearrangements and modifications may be resorted to without departing from the scope of the invention as defined in the following claims.

What is claimed is:

1. An airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a spray tip connected to the discharge end thereof, a pre-orifice assembly adjacent the discharge end of said conduit including relatively movable members defining therebetween a pre-orifice opening, and manually operable means carried by said body portion operably connected to said relatively movable members and movable to vary the area of said preorifice opening.

2. An airless paint spray gun as set forth in claim 1 wherein said relatively movable members are arranged for reciprocable movement toward and away from each other to vary the area of said pre-orifice opening defined therebetween.

3. An airless paint spray gun as set forth in claim 2 wherein said pre-orifice assembly includes biasing means and cam following means to provide said recip rocable movement of said relatively movable members in opposite radial directions with respect to the axial flow of liquid paint within said conduit.

4. An airless paint spray gun as set forth in claim 3 wherein said biasing means comprise spring means arranged to urge said relatively movable members apart and said cam following means comprise radially extending cam following arms arranged to move said relatively movable members together upon engagement with an axially movable camming member operably connected to said manually operable means.

5. An airless paint spray gun as set forth in claim 4 wherein said manually operably means comprise a control member externally mounted on said body portion for threadedly advancing said axially movable camming member.

6. An airless paint spray gun as set forth in claim 1 wherein said pre-orifice assembly comprises interfitted first and second capsule members which cooperate to support said relatively movable members and to restrain them against axial movement with respect to the axial flow of liquid paint within said conduit.

7. An airless paint spray gun as set forth in claim 6 wherein said relatively movable members are supported within a cavity defined by said capsule members.

8. An airless paint spray gun as set forth in claim 1 wherein said pre-orifice opening has an elongated cross-section including a major orifice dimension extending in a direction substantially perpendicular to the axial flow of liquid paint within said conduit.

9. An airless paint spray gun as set forth in claim 8 wherein said pre-orifice opening has an axial length at least equal to one-half said major dimension of said elongated cross-section.

10. An airless paint spray gun as set forth in claim 1 wherein said pre-orifice opening has a generally elliptical cross-section when said relatively movable members are moved to a minimum area position.

11. An airless paint spray gun comprising a conduit adapted to be connected to a source of paint under pressure, a spray tip having an elongated spray opening connected to said conduit, an adjustable pre-orifice in said conduit upstream from said spray opening, said pre-orifice including opposed surfaces movable toward and away from each other, said surfaces in one position defining an elongated pre-orifice with its long axis substantially parallel to the long axis of said spray opening and being movable away from each other to increase the area of said pre-orifice.

12. An airless paint spray gun as set forth in claim 11 wherein said area of said pre-orifice opening is adjustable in size from a value equal to from about one-fourth to about twice the area of said elongated spray opening.

13. An airless paint spray gun as set forth in claim 11 wherein said surfaces are provided by relatively movable members arranged for reciprocable movement toward and away from each other.

14. An airless paint spray gun as set forth in claim 13 wherein said adjustable pre-orfice includes biasing means and cam following means to provide said reciprocable movement of said relatively movable members.

15. An airless paint spray gun as set forth in claim 13 wherein said relatively movable members are mounted within pre-orifice assembly, said spray tip and said preorifice assembly including interfitting orientation surfaces for maintaining said long axes of said elongated spray opening and said pre-orifice opening in said substantially parallel relationship.

16. An airless paint spray gun as set forth in claim 15 wherein said relatively movable members are sealed within said pre-orifce assembly by a spring biased means.

17. In an airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid under pressure and adapted to have a spray tip providing an elongated spray opening connected to the discharge end thereof the improvement comprising an adjustable pre-orifice assembly in said conduit upstream from said spray opening, said pre-orifice assembly including relatively movable surfaces defining therebetween a pre-orifice opening coaxially disposed with respect to said spray opening, and said relatively movable surfaces being movable to vary the area of said pre-orifice opening.

18. The pre-orifice assembly as set forth in claim 17 wherein said relatively movable surfaces are arranged for reciprocable movement to vary the area of said preorifice opening.

19. The pre-orifice assembly as set forth in claim 18 wherein said pre-orifice assembly includes resilient biasing means and cam following means to provide said reciprocable movement.

20. The pre-orifice assembly as set forth in claim 19 wherein said resilient biasing means comprise spring means operably connected to bias said relatively movable surfaces apart and said cam following means comprise cam following arms operably connected to move said relatively movable surfaces together.

21. The pre-orifice assembly as set forth in claim wherein said relatively movable surfaces are supported within a cavity defined by said pre-orifice assembly.

22. The pre-orifice assembly as set forth in claim 21 wherein said spring means are mounted within said cavity and said cam following arms radially extend from said cavity for engagement with an axially movable camming member.

23. The pre-orifice assembly as set forth in claim 17 wherein said pre-orifice opening has an elongated cross-section in at least one position of said relatively movable surfaces, and said pre-orifice assembly in cludes alignment means for engaging a spray tip connected to the discharge end of said conduit and maintaining the long axis of said pre-orifice opening in substantially parallel relationship with the long axis of the spray opening.

24. The pre-orfice assembly as set forth in claim 23 wherein said relatively movable surfaces include opposed, relatively movable curved surface portions which cooperate to provide said pre-orifice opening with a generally elliptical shaped cross-section in said one position of said relatively movable surfaces.

25. The pre-orifice assembly as set forth in claim 24 wherein said relatively movable surfaces include substantially planar surface portions transversely disposed with respect to said curved surface portions, said relatively movable surfaces being arranged to engage one another along segments of said planar surface portions upon relative movement therebetween, the remaining segments of said planar surface portions cooperating with said curved surface portions to define said preorifice opening.

26. An airless paint spray gun comprising a body portion with a passage for paint under pressure, a flat fan spray tip having an elongated spray opening adapted to be secured to said body portion in communication with the outlet end of said passage, said body portion having a non-circular elongated pro-orifice in said passage upstream from said spray tip, and interfitting orientation surfaces on said spray tip and said body portion maintaining the long axes of said pre-orifice and said spray .opening in parallel relation.

spray tip.

30. An airless paint spray gun as set forth in claim 29 wherein said axially projecting member is frictionally locked within said recess.

31. in an airless spray gun comprising a body portion with a passage of liquid paint adapted to be connected at its inlet end to a source ofliquid paint under pressure and adapted to have a flat fan spray tip having an elongated spray opening connected to the discharge end of said conduit, the improvement comprising a pre-orifice assembly defining a non-circular pre-orifice opening upstream in said passage from said spray tip, and interfitting orientation surfaces on said spray tip and said pro-orifice assembly maintaining the long axes of said spray opening and said pre-orifice opening in parallel relation.

32. The improvement set forth in claim 31 wherein said pre-orifice assembly includes an axially projecting member having a non-circular cross-section received within a recess in said spray tip, and said interfitting surfaces are provided by said projecting member and said recess.

33. The improvement set forth in claim 32 wherein said projecting member has a generally cylindrical shape including at least one axially extending flat along its exterior surface.

34. The improvement set forth in claim 32 wherein said projecting member includes resilient biasing means for maintaining said projecting member within said recess.

35. The improvement set forth in claim 31 wherein the area of said pre-orifice opening is variable.

36. The improvement set forth in claim 31 wherein locking means are provided for maintaining said preorifice assembly and said spray tip is a predetermined axial relationship.

37. The improvement set forth in claim 36 wherein said interfitting surfaces and said locking means are provided by an axially projecting member having a non-circular cross-section extending from said preorifice assembly and received within a recess in said spray tip.

38. The improvement set forth in claim 37 wherein said resilient biasing means comprise an axially extending slot bisecting at least a portion of the axial length of said axially projecting member received within said recess, said recess being sized to compress and resiliently lock said bisected portion within said recess.

39. An airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a flat fan spray tip having an elongated spray opening connected to the discharge end of said conduit, said body portion having a non-circular elongated pre-orifice opening in said conduit upstream from said spray tip, said spray opening having a major opening dimension extending in a first direction and said pre-orifice having a major orifice dimension extending in a second direction, and said first and second directions being disposed in substantially parallel relationship.

40. An airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a spray tip connected to the discharge end thereof, a pre-orifice assembly adjacent the discharge end of said conduit including an axially extending pre-orifice opening adjustable in cross-sectional area, and manually operable means carried by said body portion operably associated with said pre-orifice assembly and movable to vary the area of said preorifice opening.

UNITED STATES PATENT OFFICE CER'lt -IFICATE 0F CORRECTION \t PATENT NO. 3,865,314

DATED February 11, 1975 mvmroerst Gustave S. Levey and Edward Moser It is certified that error appears in the ab0ve identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 31, after the word "in" insert a Column 4, line 39, "with" should read within Column 8, line 48, delete the word "a".

Column 9, line 3, '"is" should read in Column 9, line 63, after the word "area" insert value Column 10, line 15, "or" should read of Column ll, line 47, "operably" should read operable Column 12, line 33, after "within" insert a Column 14, line 25, "is" should read in Jigned and sealed this 1st day of July 1975.

(31x1) Attest:

C. I'ZfillSl-TALL DANN RUTH C. IZASOt-t Commissioner of Patents attesting Officer and Trademarks

Claims

1. An airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a spray tip connected to the discharge end thereof, a pre-orifice assembly adjacent the discharge end of said conduit including relatively movable members defining therebetween a pre-orifice opening, and manually operable means carried by said body portion operably connected to said relatively movable members and movable to vary the area of said pre-orifice opening.

3. An airless paint spray gun as set forth in claim 2 wherein said pre-orifice assembly includes biasing means and cam following means to provide said reciprocable movement of said relatively movable members in opposite radial directions with respect to the axial flow of liquid paint within said conduit.

15. An airless paint spray gun as set forth in claim 13 wherein said relatively movable members are mounted within pre-orifice assembly, said spray tip and said pre-orifice assembly including interfitting orientation surfaces for maintaining said long axes of said elongated spray opening and said pre-orifice opening in said substantially parallel relationship.

18. The pre-orifice assembly as set forth in claim 17 wherein said relatively movable surfaces are arranged for reciprocable movement to vary the area of said pre-orifice opening.

21. The pre-orifice assembly as set forth in claim 20 wherein said relatively movable surfaces are supported within a cavity defined by said pre-orifice assembly.

23. The pre-orifice assembly as set forth in claim 17 wherein said pre-orifice opening has an elongated cross-section in at least one position of said relatively movable surfaces, and said pre-orifice assembly includes alignment means for engaging a spray tip connected to the discharge end of said conduit and maintaining the long axis of said pre-orifice opening in substantially parallel relationship with the long axis of the spray opening.

25. The pre-orifice assembly as set forth in claim 24 wherein said relatively movable surfaces include substantially planar surface portions transversely disposed with respect to said curved surface portions, said relatively movable surfaces being arranged to engage one another along segments of said planar surface portions upon relative movement therebetween, the remaining segments of said planar surface portions cooperating with said curved surface portions to define said pre-orifice opening.

26. An airless paint spray gun comprising a body portion with a passage for paint under pressure, a flat fan spray tip having an elongated spray opening adapted to be secured to said body portion in communication with the outlet end of said passage, said body portion having a non-circular elongated pre-orifice in said passage upstream from said spray tip, and interfitting orientation surfaces on said spray tip and said body portion maintaining the long axes of said pre-orifice and said spray opening in parallel relation.

27. An airless paint spray gun as set forth in claim 26 wherein said interfitting orientation surfaces are provided by an axially projecting member extending between said body portion and said spray tip.

28. An airless paint spray gun as set forth in claim 27 wherein said axially projecting member has a non-circular cross-section.

29. An airless paint spray gun as set forth in claim 28 wherein said axially projecting member is fixed to said body portion and extends into a recess provided by said spray tip.

31. In an airless spray gun comprising a body portion with a passage of liquid paint adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a flat fan spray tip having an elongated spray opening connected to the discharge end of said conduit, the improvement comprising a pre-orifice assembly defining a non-circular pre-orifice opening upstream in said passage from said spray tip, and interfitting orientation surfaces on said spray tip and said pre-orifice assembly maintaining the long axes of said spray opening and said pre-orifice opening in parallel relation.

36. The improvement set forth in claim 31 wherein locking means are provided for maintaining said pre-orifice assembly and said spray tip is a predetermined axial relationship.

37. The improvement set forth in claim 36 wherein said interfitting surfaces and said locking means are provided by an axially projecting member having a non-circular cross-section extending from said pre-orifice assembly and received within a recess in said spray tip.

40. An airless paint spray gun comprising a body portion having a conduit adapted to be connected at its inlet end to a source of liquid paint under pressure and adapted to have a spray tip connected to the discharge end thereof, a pre-orifice assembly adjacent the discharge end of said conduit including an axially extending pre-orifice opening adjustable in cross-sectional area, and manually operable means carried by said body portion operably associated with said pre-orifice assembly and movable to vary the area of said pre-orifice opening.