US2019941A - Spray head - Google Patents

Description

R. W. TRACY SPRAY HEA'D Nbv. 5, 1935.

Filed Dec. 15, 1.934

Patented Nov. 5, 1935 PATENT' OFFICE SPRAY HEAD Robert W. Tracy, Toledo,.0hio, asdgnor to The De Vilbiss Company, Toledo, Ohio, a corporatlon of Ohio Application December 15, 1934, Serial No. 757,593

This invention relates to spray painting apparatus and is more particularly directed to the spray-head or cap portion of such apparatus.

:The invention utilizes fiattening jets acting on the main surface coating stream and formed by the convergence of a plurality of properly directed air streams, in combination with one or more pairs of atomizing jets.

The primary object of the present invention is the provision of -a cap having provision for discharging a plurality of air jets acting on the spray discharge ofl a paint guntp` completely atomize and shape the spray.

Another object of the invention is the provision of opposed flattening jets acting on the spray discharge of a paint gun in combination with atomizing jets striking the spray discharge in advance of the flatteningjets at a high angle to produce a complete atomization of the heavy :enter particles of the spray` before being flatened.

Another object of the invention is the provision in a paintv gun of opposed stream flattening jets in combination with stream atomizing jets of a relatively great volume so that the gun can give a larger uniform pattern than has been heretofore possible. j

Other objects and advantages of the invention will become apparent as the description proceeds, reference being had to the accompanying drawing, in which- Figure 1 is a perspective view of a spray-head or cap having fiattening and atomizing jets issuing therefrom and disposed in accordance With my invention, and Figs. 2, 3, 4, and are modified forms of the invention disclosing various combinations of air streams to form the fiattening and j atomizing jets.

nection With a cap having a body I fromwhich the usual supplemental air discharge horns 3 and 4 project. The body I is provided with the usual central liquid discharge orifice 6 and central air orifice 8 concentric therewith. 'Thus, the air supported liquid stream issues fromthe gun in the usual circular stream form.

The spray stream is first impinged' and atomized by air streams I2 and I3 issuing from orifices I0 and II in the face of the cap. The streams from these orifices are each at a wlde'acute angle relative to the line of discharge so that the air pierces the stream and breaks up the heavy central particles. The shape of the reulting stream is analagous to an hour glass, p

VHaving' been thoroughly broken up by the atomizing streams` I2" and I3, the stream is then fiattened to its desired fan shape. Instead of single opposed jets ordinarily used to shape the stream, the present invention utilizes 'opposed fiattening' jets each formed by the convergence of a plurality of diiferently directed streams. It has been found that fiattening jets so formed envelope the stream and prevent over-spray even though a high penetration of the atomizing jets is employed. Thus, the air horns 3 and 4 are each provided with the usual discharge orifices M and I 5 from which issue air streams I 6 and I'l. Smaller orifices IB and I9 are provided in the face of the cap, and air streams 20 and.v 2| issue therefrom directed toward the spray stream, at a smaller angle than the streams IB and I 1, but in the same plane. These streams and 2| impinge on, and fiatten streams IS and ll, so that the resultant combined jets 22 and 23 are 20 elliptical and strike-the spray in the form of a fan. The resultant jets 22 and 23 envelope'the spray to'an extent that all of the particles are properly directed and over-spray is substantially eliminated. 25

included. angle between the atomizing jets'cannot be greater than 40. A more direct impingement scatters the spray sobadly thatthe fiattening jets are unable to control the pattern. 35

'Further, an atomizing orfice larger than .038"

also would cause an uncontrollable disturbance of the main stream. gun so constructed will produce an elliptical pattern having a major axis 9 long. 43 By using the elliptical fiattening jets 22 and 23 in combination with the atomizing jets I 2 and I3, it is found that the included angle between the jets I2 and 13 can be increased to as high as 100 without disturbing the, pattem. The ldi- 45 ameter of the atomizing orifices I0 and I I can be increased to .052". The gun will give a highly satisfactory elliptical pattern having a long axis of substantially 14, and is thus capable of covering more surface in the same length of 50 time than the construction compared in the paragraph above at the same distance from the gun and, with an atomization of the same order.

In the form shown in Fig. 2, the spray is first acted upon by atomizing jets which are elliptical,

the major axis of the ellipse being in the same plane as the direction of spray discharge. This jet is formed by the convergence of two air streams 30 and 3| from orifices 32 and 33 verticaily spaced from each other on the face of the cap. The oriiices direct the air toward the main spray stream in a manner so that the air streams 30 and 3| converge to form a resultant air jet 34. In the interests of clarity the reference numerals have been applied only to one of the streams. It will be understood that in every instance the jets on each side of the main spray discharge are similar. After having been atomized by the jets 34, the stream is fiattened by jets JS in the same manner as in Fig. 1.

In the modification disclosed in Fig. 3, the atomizing jet is somewhat deprived if its piercing power, so that this form can be advantageously employed with thinner liquids. Atomizing air oriflces 4| and 42 are provided on each side of the center of the cap and are horizontally spaced. The discharge stream 43 from the outer oriflce is flattened by the stream M from the inner` orifice, so that a resultant fan-shaped atomizing jet 45 is formed. It will be seen that this jet is elongated in a Vertical plane relative to the plane of the main flattening jet, designated l6, which subsequently acts on the stream.

When it is desired to spray relatively viscous liquids to obtain very thorough atomization, it is desirable to provide a plurality of atomizing jets acting successively on the spray discharge. In Fig. 4 is disclosed a form in which ports 50 are disposed on each side of the center in a vertical plane, and ports are disposed on each side of the center in a horizontal plane. Jets 52 and 53 issue from these respective orices and strike the spray stream successively, one after the other, in planes 90 apart. The stream being thus thoroughly atomized is then fiattened into the desired shape by the iiattening jets S5, formed as in the previously described modifications.

Another cap to be used, when a high degree of atomization is desirable, is shown in Fig. 5. Single atomizing jets Oli are provided, and double atomizing jets 63, formed by oonvergence of streams ll and C2, are also provided, the resultant jets 83 being disposed in a plane 90 removed from the plane of the single jets. In the form shown the atomizing jets 63 are eliiptical with the major axis in the same plane as the direction of the main spray, as in Fig. 2. It will be appreciated that this form provides a knife-like -penetration for the resultant jets which, combined with the atomizing power of the jets 60, produces a very flnely divided spray. The spray is, however, enveloped by the elliptical flattening jets G5, so that the pattern of the spray stream is regular.

It will be appreciated that the ang'ular dsposition of the several jets disclosed in each modification is merely illustrative, and has been exaggerated in some instances in the interests of clarity. Obviously, the angles may be varied throughout a wide range without departing from the invention as defined in the appended claims.

It should be pointed out that in the specification, the term ujet has been employed to designate a stream of air impinging directly on the spray discharge, whereas the term air stream" has been used to designate either of two converging air bodies uniting to form a jet.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent, is:

1. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having in combination, atomizing air orifices adapted to emit streams of atomizing air acting on the stream of coating liquid, and supplemental air oriiices adapted to emit, on each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single fiattening and enveloping jet of air, striking said stream after said atomizing air streams have acted upon the stream.

2. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having in combination, atomizing air orifices adapted to emit jets of atomizing air acting on the stream of coating liquid, and supplemental air orifices in a plane at right angles to the plane of said atomizing jets and adapted to emit, on each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single flattening and enveloping jet of air striking said stream after said atomizing jets have 'acted upon the stream.

3. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having in combination, a plurality of atomizing air oriiices on each side of said stream adapted to emit diiferently directed streams of air which merge to form a single atomizing jet acting on each side of said stream, and supplemental air orifices in a plane at right angles to the plane of said atomizing air jets and adapted to emit, on each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single fiattening and enveloping jet of air striking said stream after said atomizing jets have acted upon the stream.

4. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having in combination, a plurality of atomizing air oriiices adapted to form a fan-shaped jet of air acting on said stream of 15 coating liquid on each side of said stream, and supplemental air oriiices in a plane at right angles to the plane of said atomizing jets and adapted to emit, on each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single flattening and enveloping jet of air striking said stream after said atomizing jets have acted upon the stream.

5. A spray-head of the class described having 55 provision for' discharging an air supported stream of coating liquid, and having in combination, a plurality of atomizing air oriiices adapted to form a fan-shaped jet of air acting on each side of said stream of coating liquid, the jet being elongated in the direction of discharge of said stream, and supplemental air orifices in a plane at right angles to the plane of said atomizing air jets and adapted to emit, on each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single flattening and enveloping jet of air striking said stream after said atomizing jets have acted upon the stream.

6. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having inl combination, a plurality of atomizing air oriflces adapted to emit diiferently directed jets of air which act successively in pairs on said stream of coating liquid, and supplemental air orifices adapted to emit, on

each side of the stream of coating liquid, a pair of air streams which converge before striking said stream to produce a single fiattening and enveioping jet of air striking said stream after said atomizng jets have acted uponthe stream.

'7. A spray-head of the class described having provision for discharging an air supported stream of coating liquid, and having in combination, a. plurality of atomizing air orifices adapted to emit 10 differently directed jets of air which act successively in pairs on said stream of coating liquid,

one of said pairs of atomizing jets being fanshaped, and supplemental air orifices adapted to emit, on each side of the stream of coating liquid,

. a pair of air streams which converge before strik- ROBERT W. TRACY.

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