US1767822A - Apparatus or tool for applying coating - Google Patents

Description

June 24', 1930. w. B. THOMPSON APPARATUS QR TOOL FOR APPLYING COATING I Filed Aug. 7,1925

Patented June 24, 1930 WAYNE B. THOMPSON, or WINCHESTER, MASSACHUSETTS,

APPARATUS 0R TOOL FOR APPLYING COATING Application filed August 7, 1928. Serial No. 297,983.

The present invention relates to an apparatus or tool for applying coating mate rial and more particularly to an air brush or spray gun of the type which is oscillated 0 over the surface to be coated and which carries its own supply of coating material.

Usually the coating material is supplied to the spray gun from a container detachably connected to a cover secured to the spray gun. The cover is provided with an outlet for conducting the coating material from the container to the spray gun and also with an inlet or vent for admitting atmospheric air to the interior of the container. The compressed air, or other motive agent, which rushes through the spray gun to. atomize the discharged coating material, produces a condition of. unbalanced pressure within the container so that the atmospheric air which enters the container through the inlet forces the coating material in the container through the outlet and into the spray gun for discharge therefrom. In the normal operation ,of' the spray gun the inlet for the atmospheric air is located above the level surface of the coating material in the container. It often happens that it is desirable, and even necessary, in order to coat a surface above the spray gun to operate the spray gunin an abnormal position in which the level surface of the coating material is substantially above the inlet for the atmospheric air. Heretofore, it has been utterly impossible to operate the spray 35 gun in the abnormal position referred to without coating material flowing out of the inlet for the atmospheric air.

The principal object of the present invention is to produce a spray gun of the type hereinbefore referred to which may be operated upside down or in any other abnormal position in which thelevel surface of the coating material in the source of supply is substantially above the atmospheric air inlet thereto.

7 To the accomplishment of this object, a feature of the present invention contemplates the provision in a spray gun having a source of supply for the coating material, including an outlet for the coating material of supply for. the coating material. It is I preferred, however, to maintain the inlet normally open and provide means for closing the inlet automatically only when the spray gun is operated in such an abnormal position that the coating material has a tendency to flow through the inlet.

In its broadest aspects the valve maybe operated automatically to close the inlet for the atmospheric air upon the development of a head of coating material upon the inlet in any manner found desirable or expedient. By a head of coating material upon the inlet I mean the vertical depth of the inlet below the level surface of the coating'material. Owing to the fact that in certain abnormal positions of the spray gun it is tipped so that the level of the coatingmaterial is flush with a portion of the inlet orifice whereby the coating material flows out of the inlet at the same time that atmospheric ,air enters the source of supply through the inlet it is preferred to provide the valve with operating mechanism for closing it, not only upon the development of a head of coating material upon the inlet, but also in any abnormal position of the sora 1 un tending to cause a flow of coatin material through the atmospheric air inlet. Accordingly, the valve is operated by gravity-actuated means which will operate automatically to maintain the inlet open when the inlet for atmospheric air is above the level surface of the coating material in the source of supply and which will operate automatically to close the inlet when the normal relationship between the inlet for atmospheric air and the level surface of the tipped so that coating material would flow out of the inlet for the atmospheric air unless thevalve was operated to close the inlet. Inasmuch as the spray gun can operate with the inlet. for atmospheric air closed for only a short period of time which is longer, however, than the time it takes for the operative or the machine "to swing the spra gun in. one direction another object of t e present invention is to provide the spray gun with means for operating the valve to open the inlet momentarily at in tervals during the oscillation of thespray gun to permit atmospheric airto enter the source of supply of coating material.

To the accomplishment of this object a feature of they present invention, contemplates the provision in a spray gun of the type which is oscillated over the surface to be coated having a source ofsupply for the coating material includingan outlet for the coating material and an inlet. for atmospheric air located normally. substantially above the level surface of the coating material in the source of supply and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material through the outlet, of, means for closing the inlet to permit the spray gun to be oscil? lated with the normal'relationship between the inlet and the level surface ofthe coating materialv substantially reversed and for opening the inlet momentarily during the suspension of the swing ng movement ofthe spray gun between oscillations.

Broa ly considered, any valve capable of being opened automatically under the influence of the inertia thereof may be employed, but it will be readily understood by those skilled in the art that a gravitv-actuated valve which is operated automatically to close the inlet is particularly adapted to open the inlet automatically unde the influence of. inertia during the pause in the swinging movement oft-he spray gun be tween oscillations. i

Further features .of-the present invention contemplate the provision of. certain devices, combinations and arrangements of parts tending to improve and simplify the opera tion ofspray guns and enable themto operate with certainty and without liability of leakage of coating material, the advantages of which will be obvious to those skilled in the artfrom thefollowing description.

"The various features of the present inventionwill be readily understood from an inmenses saection of the accompanying drawings il- "t tl" b tf "tl '1 t' t ins .ating ie es 01 ms or is 1m en 10,1 a present devised, in which,

Figure 1 1s a view in elevation of a spray gun of the type which is oscillated over the Fig. i is a view in detail end elevation of the modified valve illustrated in Fig. 3;

Fig: 5 is a view in detail sectional elevation substantially on tl1e.line..5 5, Fig. 1, container being removed, and a Fig. 6 is a view in detailsectional elevation another modifiedform of'va lve.

The snra' 'unillustrated in Fi 1 is con structed. and is operated, except for. the valve for. the vent tothe container for the coating material, substantially identical. with the spray gun disclosed in my Patent No. 1,706,006, March 19, 1929. In the illustrated embodiment. of the invention the spray gun has a body portion 7 provided with a nozzle 8. beyond which the coating material-is discharged in an atomized.condition by compressed air, oro the r motive. agent, which is introducedinto the body portion? through a pipe connection 9. llVithin the. body portion' are coating material and motive I agent valves (not shown) which are controlled by a trigger 10 pivoted on the body port-ion 7; The coating material is supplied to the body portion? from a container 11 which is detachably connected to a cover-12 secured by a nut- 13to a conduit l lon the body por tion. The cover 12is provided withan out let 15 for the coating material depending into the container 11- and also with a :vent 1 6 which is the inlet for atmospheric air. lVhen the trigger '10 is pulled the compressed rushes through the gun and is arged throughthe nozzle 8. The compressed air produces a condition of unbalanced pressure on the level surface of the coating material in the container so that the at iospheric air which enters the container through the inlet 16 forces the-coating material out of the container through'the outlet 15 and into the conduit 14 whichconducts the coating material to the inner nozzle (not shown) through which the coating material is discharged and then atomized by the coinpressed air discharged through the nozzle S.

In tne normal operation of the spray gun, in which the operative or'a machine sprays a vertical surface by oscillating the spray gun horizontally thereover, the vent or mospheric air-inlet 16 is located above the level surface of the coating material in the container and consequently there is no tend ency for the coating material to flow out of llt) the container through the inlet 16. In spraying a vertical surface by oscillating the spray gun vertically thereover at the top and/or bottom of the stroke the level of the coating material may be above the inlet 16 and consequently there is a tendency for the coating material to splash out of the inlet;

This condition is aggravated whenan attempt is made to spray a surface above the level of the spraygun. In spraying the bottoms of airplane wings which may be above the head of an operative, or in spraying theunder surfaces of objects, which may be below the head of the operative, or in spraying under surfaces reached only with difliculty, it is necessary to tip the spray gun.

so that the level of the coatingmaterial in the container is flush with or above the inlet 16 inwhich abnormal position the coating material is free to flow outof the inlet.

In order to permit the spray gun to be used in situations requiring its tipping without liability of a flow of coating material through the inlet 16 I have provided the inlet with a valve seat 17 which in its simplest form may be engaged normally by a spring pressed valve 18 (Fig. 6). The valve 18 is provided with a stem 19 which extends above the inlet 16 so that by engagement with the stem at frequent intervals the operative may release the valve to open the inlet and allow atmospheric air to enter the container.

However, as the operation of the spray gun in a tipped position is abnormal I prefer to operate the valve to open the inlet when the spray gun is operated normally with the inlet above the level surface of the coating material in the container and to close the inlet when the spray gun is operated abnormally with the level surfaceof the coating material above the inlet. To this end the inlet 16 may be provided with a seat 20 (Fig. 2) which is engaged by a valve 21 pivotally mounted upon the horizontal arm of bell cranklever 22 pivoted on a support 23 secured by a screw '241to the cover 12. The vertical arm of the bell crank lever 22 is provided with a weight or bob 25. The valve 21 is heldin an upright position by a stem 26 secured to the valve and engaged loosely with the inlet 16.

\Vith this construction the valve 21 is held away from its seat by the bob when the spray gun is operated normally with the inlet 16 above the level surface of the-coating material in the container. As soon, however, as the spray gun is tipped, the bob 25 under the influence of gravity operates the valve 21 to close the inlet 16.

It will be apparent from an inspection of Fig. 2 that the inlet 16 is closed when the spray gun is tipped in one direction only. In order to close the inlet 16 when the spray gun is tipped in opposite directions in the same plane the valve 21 is secured to one end of a rod 27 (Figs. 3 and 4) the other end of which is pivoted on a pin 28 secured to a head 29. The head 29 is formed on one end of a rock-shaft 30 which is journaled in a standard 31 having a screw-threaded engagement with the top of the cover T2. The rock-shaft is held from movement longitudinally of its bearing in the standard 31 by a pin 32. The rock-shaft on the end opposite the head 29 is provided with a rod 33 having itslower end secured to a weight or bob 34. With this constructionthe inlet 16 is closed when the spray gun is tipped in opposite directions inthe same plane. That is, the bob 34 has extremes of movement on opposite sides of the standard 31 in each of i which the valve 21 is engaged Withthe valve having external screw threads engaged with similar threads formed concentric to the inlet 16 in the'bottom of the cover '12. The cage 35 is provided with a valve seat 37 which may be engaged by a valve 38 to close the inlet 16. The valve 38, which is sub stantially oval in shape and which is provided with a central peripheral skirt 39 to increase the weight of the valve, is looselysupported'upon a flat surface 40 formed on a semispherical ball 400. To reduce the friction between the valve 38 and the ball 400 to a minimum they are constructed from different metals. Preferably, the valve 38 is brass while the ball 400 is hardened steel, the surface 40 being polished. Depending from the ball 400 is a lead weight or bob 41. Normally the valve 38 maintains its engagement with the ball 400 underth'e influence of gravity. The valve 38 is prevented from rolling out of engagement with the surface 40 by a stem 42 secured to the valve 38 and engaged loosely within the inlet 16.

, The ball 400 is suspended loosely in an opening 43 formed in a plate 44 which is secured by nuts 45 to standards 46 which arestaked to a plate 48 engaged with the bottom of the cover 12. The plate 48 is provided with a central opening 47 loosely sur rounding'the cage 35 and is secured to the cover 12 by a nut 49 engaged with the threads 36 on the cage 35.

' lVith this construction when the spray gun is tipped the bob 41 will tend to maintain its original position under the influence of gravity and thus will turn the ball 400 in the opening 43 and cause the surface 40 to at the end of the sprayiii wedge the valve 38 into engagement with the seat 37 to close the-inlet. 1

It is sometimes desired to oscillate the spray gun continuously over the surface to be coated while the spray gun is tipped in an abnormal position in which the inlet is closed. To permit this the inlet must be opened momentarily at intervals to provide the interior of the container with atmospheric air. The particular mechanisms for actuating the valve to close the inlet illustrated in Figs. 2, 3, l, 5' and 6 have all been selected because they are all adapted to open the inlet momentarily at the end of each oscillating stroke of the spray gun. Thisis due tothe inertia of the valve (Fig. 2) and the bobs 21 and 41 (Figs. 3 and 5) which causes the valve or bobs to continue to travel in the direction of the oscillating movement of the spray gun when 1t 1s stopped suddenly in preparation for the return oscillating movement.

It will be apparent to those skilled in this art that changes may be made in the details of construction, the described and illustrated embodiments of the invention being intended as exploitationsof its underlying essentials, the features whereof will be definitely stated in their true scope in the claims hereto ap;

pended.

hat is claimed as new, is:

1. In a spray gun, the combination with a source of supply for the coatingmaterial, including an outlet for the coating material and an inlet for atmospheric air, and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material through the out-l et', of a valve for closing the inlet during the operation of the spray gun.

'2; In a spray gun, the combination with a source of supply for the coating material, including an outlet for the coatingmaterial andan inlet for atmospheric air,.and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material'through the outlet, of' a valve operating automatically for closing the inlet when the gun is operated in an abnormal position such that coating material tends to' flow through the inlet.

8. Ina spray gun, the combination with a source of supplyv for the coating material, including an outlet for. the coating material and an inlet for atmospheric a-irlocatednormally substantially above the level: surface of the coating material in the source of supply, and means for producing a condition of unbalanced pressure within the'source of supply whereby the atmospheric air forces the coating material through the outlet, of a valve operating automatically upon the ply, and means for producing a condition ofunbalanced pressure within the source of supply whereby the atmospheric air forcesthe coating material through the outlet, of a valve, ant gravity-actuated me'ansopera- .tively connected to the valve for operating the valve automatically. to close the inlet when the normal relationship between. the inlet and the level of the coating material is reversed.

5; In spray gun of the type which is oscillated over the surface to be coated, the combination with a source of supply for the coating material, including an outlet for the coatin material and an inlet for atmospheric air located normally substantially above the level surface of the coating material in the source of supply,.and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating materialthrough the outlet, of means for closing the inlet to permit the spray gun to be oscillated with the normal relationship between the inlet and the level surface of the coating material reversed.

6 In a spray gun of the type which is oscillated over the surface to be coated, the combination wi h a sourceof supply for. the coating material, including an outlet for the coating material and an inlet for atmospheric air located normally substantially above the level surface of the coating material in the source of supply, and means for producing a condition of unbalanced pressure within the source of supply where'- by the atmospheric air forces th'ecoatingmaterial through the outlet, of means for closing' the inlet to permit the spray gun to be oscillated with the normal relationship between the inlet andethe level surface of the coating material reversed and for opening the inlet momentarily during the suspension of the swinging movement of the spray gun between oscillations.

In a spray gun of the type which is oscillated over the surface to be coated, the combination with a source of supply for the coating materialincludingan outlet for the coating material. and an inlet for atmose pheric air, and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material throughthe outlet, of a: valve for closing the inlet and a device operatively connected thereto for opening the valve through the inertiaof said device during the suspension of the swinging movement of the spray gun between oscillations.

8. In a spray gun of the type which is oscillated over the surface to be coated, the combination with a source of supply for the coating material including an outlet for the coating material and an inlet for atmospheric air located normally substantially above the level surface of the coating ma terial in the source of supply and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material through the outlet, of a valve, and a device operatively connected to the valve for operating the valve automatically to close the inlet when the normal relationship between the inlet and the level of the coating material is reversed and for opening the valve through the inertia of said device during the suspension of the swinging movement of the spray gun between oscillations.

9. In a spray gun, the combination with a source of supply for the coating material,

including an outlet for the coating material and an inlet for atmospheric air located normally substantially above the level surface of the coating material in the source of supply, and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material through the outlet, of a valve seat in the inlet, a valve therefor, and gravity-actuated means operatively connected to the valve for maintaining the valve out of contact with its seat to open the inlet in the normal relationship between the inlet and the level surface of the coating material and for engaging the valve with its seat to close the inlet when the normal relationship between the inlet and the said level surface is reversed.

10. In a spray gun, the combination with a container for the coating material, a cover, to which the container is detachably connected, provided with an outlet for the coating material and an inlet for atmospheric air, and means for producing a condition of unbalanced pressure within the container whereby the atmospheric air forces the coating material through the outlet, of a valve, and a bob connected to the valve and movable to operate the valve to close the inlet.

11. In a spray gun, the combination with a container for the coating material, a cover, to which the container is detachably connected, provided with an outlet for the coat ing material and an inlet for atmospheric air, and means for producing a condition of unbalanced pressure within the container whereby the atmospheric air forces the coating material through the outlet, of a valve, a rock shaft connected at one end to the valve, and a bob connected to the other end of the rock shaft and movable to rock the shaft and thereby operate the valve to close the inlet.

12. In a spray gun, the combination with a container for the coating material, a cover, to which the container is detachably connected, provided with an outlet for the coating material and an'inlet for atmospheric air and v means for producing a condition of unbalanced pressure within the container whereby the atmospheric air forces the coating material through the outlet, of a valve, and a bob operatively connected thereto and movable relatively to the cover under the infiuence of gravity and inertia to operate the valve to close and open the inlet respectively.

13. In a spray gun, the combination with a source of supply for the coating material, including an outlet for the coating material and an inlet for atmospheric air, and means for producing a condition of unbalanced pressure within the source of supply whereby the atmospheric air forces the coating material through the outlet, of a valve, and

a bob operatively connected to the valve for operating the valve automatically under the influence of gravity to close the inlet andfor operating the valve automatically under the influence of the inertia vof the bob to open the inlet while the bob is under the influence of gravity tending to maintain the inlet closed.

In testimony whereof I have signed my name to this specification.

WAYNE B. THOMPSON.

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