US 2708095 A
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May l0, 1955 R. B.'M|rcHE|.L
SPRAY GUN AIR VALVE Filed Jan. 25, 1951 ELEM/TE.
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Cttorneg TEA United States Patent SPRAY GUN Am VALVE Robert Bertram Mitchell, Sanderstead, England, assigner to The De Vilbss Company, Toledo, Shin, a corporation of Ohio Application `l'alruary 25, 1951, Serial No. 207,724
1 Claim. (Cl. 251-229) This invention relates to spray guns utilizing compressed air for atomizing the spray material and having diametrically opposed air jets for attening the atomized material stream into fan shape. In order to secure spray patterns of various widths adaptable for effectively coating surfaces of different areas, it is customary to have an adjustable valve in the passage delivering air for such jets. The flattening force of the air jets is reduced or increased by closing or opening movement of the valve.
As usually constructed this valve has a tapered inner end which seats within the air passage, a threaded shank by which it is rotatably mounted, and an exterior knurled head for manual adjustment. In order to provide a broad range of adjustment a relatively fine thread is utilized. It Vis thus possible to set the valve for a very particular flow of air that will shape the spray pattern most suitably for a certain type of surface.
In many spray tinishing operations the character of the products being coated is such that a single width of spray is satisfactory for all purposes. However, in other finishing processes, there are occasional surfaces of restricted area, for which a Wide spray pattern, selected for a major part of the coating work, is not suitable.
Since excessive waste from overspray or too heavy a coating results from the use of too wide a spray pattern, under such circumstances it is desirable for the operator to temporarily screw the spray width valve at least part way toward a closed position. He must subsequently carefully open it again to the predetermined setting considered best for the predominant type of surfaces. Because of the line thread on the valve shank, considerable rotary movement is required in this closing and opening of the valve and valuable time is lost in the accompanying interruption of the spraying operation.
The purpose of my invention is the provision of a valve structure for controlling the air delivered to flattening Y jets in a spray gun in which the advantage of close adjustment is retained and which in addition has means for easy and rapid closing and opening movement of the valve with stop means limiting the opening movement to the valve position previously selected for normal use.
This improved action is secured by mounting the valve for both gradual threaded adjustment and independent sliding axial movement. This is accomplished by having an unthreaded valve shank fitting snugly for relative axial movementl within an exteriorly.threadedirtatable' sleeve andprovfidingbetween the valv'eslr'ankf andt'sle'eve a longitudinal slot and pin connection. y
An` embodiment of my invention is hereafter described in detail and illustrated in the accom'panyinfg` drawings in which- Figure 1 is a central vertical longitudinal section of a spray gun incorporating the invention;
Figure 2 is a similar section of the valve assembly of the spray gun of Figure l; in this view the valve is in closed position; y
Figure 3v is a side elevationpartlyin: section-'tof 4vtlrefvalve assembly withA the valve in open position; 'and Figure 4 is a side elevation of the valve and the exteriorly threaded sleeve.
The spray gun of Figure l is a conventional design to which my invention has been adapted. It has a depending handle 1 in which there is an air supply passage 2. 'The air travels therethrough past valve 3, which is opened by rearward movement of the trigger 4 against the exteriorly extending valve spindle 5. The air flow continues upwardly through port 6 into the horizontal bore 7. The air is here divided into two parts, one travelling forwardly exteriorly of the hollow rod 8. This air passes through opening 9 into annular chamber 10, forwardly around the spray material tip and out the annular port surrounding the outlet end of the tip. This portion of the air atomizes the spray material discharged from the tip.
The second part of the air reaching bore 7 normally enters the lateral ports 12 into the interior of hollow rod S. Under control of valve 13 this air travels forwardly out the open end of rod 3 into annular chamber 14 from whence it passes ahead to the outlets in horns 15. This air projected against opposite sides of the atomized material stream attens it into fan shape.
The hollow rod 8, in addition to providing a passage for the air going to the horns, serves to retain the spray head 16 in assembled relation with the spray gun body 17. lt does this by having a forwardly facing shoulder abutting against the edge of the rearward opening of bore 7 and a threaded forward end engaging the sprayhead. This double function of rod 8 is a feature of the particular spray gun utilized to illustrate an embodiment of this invention and is incidental to the invention. The latter may be as easily applied to spray guns not having this feature.
The interior of the rod t3 is divided into two parts by the annular ange 1S forming a valve seat 19 for the valve 13. A sleeve Z0 is threaded into the rear end of the rod t5, the joint between them being sealed by packing 21 held in place by nut 22. To resist accidental turning of the sleeve 20 its forward end is slotted at 23 and the sections between the slots are sprung outwardly against the inner wall of rod 8. The valve 13 extends neatly through sleeve 20 and the exterior joint therebetween is sealed by packing 24 held in piace by nut 2S. For manual adjustment of valve 13 there is mounted on the exterior end of the valve shank a knurled knob 26.
Midway of the sleeve 2da. longitudinal slot 27 is cut therethrough. Into thiszsloty snugly ts the head of a screw 2S `from thesideofztheffvalve shank. Through this slot andscrew en'gageraeaf yrtitevalve may be moved longitudinall'yin relationit' tha-,sleeve within the limits of the length of the slot. Wi -arotary movement the valve and sleeve must turn togethen,
In normal usageithe. valve 13 is in open position rearwardly spaced from the valve seat 19 with the head of the screw 28 against the rear end of slot 27. Shouldk some adjustment in the position of the valve be desired the knurled knob 25 is turned. Through the engageme t of the screw 23 on the valve shank with the Slot 27 the sleeve 2i), the latter is rotated by the turning of knob 2d and is gradually moved axially through 4its threaded engagement with the interior of rod 8. The degree of opening of the valve is thus modied according to requirements.
Should a succession of comparatively large y,surface areas to be coated be interrupted by narrow surfaces too restricted in area to be properly coated by a fan pattern the knob 26 is pushed forwardly sliding the valve to its seat with the head of screw 23 travelling lengthwise of the-slot 27.
'When the work for the narrow spray pattern is completed the knob 26 is pulled rearwardly until the head of the screw 28 reaches the rear end of the slot 27. As this doesnt disturb the rotary position of the sleeve, the fan pattern previously selected for the regular run of surfaces is thus again produced.
The length of the threads between the sleeve 20 and the interior of rod 8 is such that the valve may be rrnly held to its seat for a long spell of coating of surfaces of limited dimensions by turning the valve and coacting sleeve until the valve reaches its seat.
From the preceding it may be understood that the slot and screw engagement between the valve shank and sleeve in association with the threaded mounting of the sleeve provides means for both gradual adjustment of the valve position and rapid closing and reopening sliding movement of the valve.
While a slot and screw engagement between the valve shank and the surrounding sleeve is utilized in the preferred embodiment, it is realized that there are analogous structures which would serve as well. For instance a groove of suieient depth would function as effectively as the slot. Then teo, a pin or flattened tongue could be feasibly substituted for the screw. It is not considered that such replacements would depart from the spirit of the invention and that slot and screw as herein specified should accordingly be interpreted broadly.
Also, it may be well to point out that it is not essential that the slot be in the sleeve and the pin or screw be in the valve shank as the reverse positioning would work as well. In addition, it may be observed that the valve shank could have a threaded engagement with the sleeve and the latter a slot and screw engagement with the rod without any loss in functions over the preferred form. For this reason the scope of this invention is not considered limited to a particular location of such engaging structures.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
In a spray gun air valve, a unitary valve casing with Cal an air passage therethrough, said passage having a lateral entering port and an axial discharge port, a valve seat within the passage between the two ports, a valve for axial adjustment toward and away from said seat, a valve shank, a rotatable sleeve threadedly engaged within the casing and encompassing said shank, a pin and longitudinal slot connection between the sleeve and shank within the valve casing, the pin of said connection extending radially from the valve shank and the longitudinal slot of said connection located in the wall of the sleeve and cutting through the portion of the sleeve which is externally threaded for engagement within the casing, a single manipulable head on the outer end of said shank by a manual push or pull of which the valve is moved axially within the limits permitted by the pin and slot connection toward or away from the valve seat, and by a manual turning of which the sleeve is rotated upon its threaded engagement within the casing through the pin and slot connection between the sleeve and the shank, means located intermediate the manipulable head and the pin and slot connection for frictionally retaining the valve in any selected position relative to the sleeve, and means for frictionally retaining the sleeve in any selected position relative to the casing.
References Cited in the ile of this patent UNITED STATES PATENTS 526,176 Blair Sept. 18, 1894 733,532 Bailey July 14, 1903 1,379,389 Brassington May 24, 1921 1,710,488 Oliphant Apr. 23, 1929 2,511,626 Einbecker Jan. 13, 1950 2,514,025 Bush July 4, 1950 2,559,407 Dalrymple July 3, 1951 2,626,122 Lammirnan Jan. 20, 1953 FOREIGN PATENTS 8,318 Great Britain 1894