US 3212715 A
Description (OCR text may contain errors)
Oct. 19, 1965 Filed June 19, 1963 E. H. COCKS SOLENOID AIRLESS SPRAY GUN 2 Sheets-Sheet 1 INVENTOR K: x-ncoms,
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ATTORNEYS Oct. 19, 1965 E. H. cocKs SOLENOID AIRLESS SPRAY GUN 2 Sheets-Sheet 2 Filed June 19, 1963 INVENTOR ma Accaovs,
BY flaw & @u'amwyw ATTORNEY5 United States Patent 3,212,715 SOLENOID AIRLESS SPRAY GUN Eric H. Cocks, 21 Crane Ave., West Caldwell, NJ. Filed June 19, 1963, Ser. No. 289,030 1 Claim. (Cl. 239-125) This invention relates to a spray gun, and more particularly to an airless spray gun used to atomize fluids by hydraulic pressure without the use of a compressed air supply.
In the field of automatic spray painting it is desirable that the spray guns be trouble free and repetitive in action, since in many instances there are not attendants to make corrections for erratic operation. An electrically operated spray apparatus is ideally suited for automatic operation, particularly when the apparatus is at a location remote from the point of control. The use of a solenoid control for operating the valve mechanism of a spray gun has been suggested in the past, and this arrangement is adapted readily for automatic operation. However, with all of the known devices, the problems of erratic plunger operation because of improper cleaning and excessive wear have remained a deterrent for the production of an apparatus having reliable operations. The principal reason for this is that the structure of the gun does not lend itself readily to a complete cleaning or flushing to remove old fluids from the operating mechanism.
It is an object of this invention to provide a spray gun for high pressure airless spraying which will be simple in construction and rapid and reliable in operation.
Another object of the invention is to provide a spray gun which is not subject to leakage around seals under pressure.
Another object of the invention is to provide a spray gun which is cleaned easily both internally and externally.
A further object of the invention is to provide an electrically operated spray gun with means for quickly and reliably connecting the operating solenoid to an external power supply.
A still further object of the invention is to provide an electrically operated spray gun suitable for hand operation.
In accordance with the invention these objects are realized in an apparatus comprising a cylinder having end closure members forming a hollow housing. The end closure members are held in position by a tubular member which is threaded at both ends and mounted concentrically with said cylinder. One end of the tubular member is threaded into the first closure member to define a fluid chamber. The first closure member also has an aperture with a resilient valve seat insert communicating with the fluid chamber.
The tubular member has an internal fluid passageway in alignment with the fluid chamber. The pasageway is enlarged at the end nearest the first closure member to the same diameter as the fluid chamber. A valve plunger having an internal fluid passageway is slidably positioned within the enlarged end of the tubular member. One end of the plunger has a tapered tip which serves as the closure for the resilient valve seat insert. A solenoid is positioned within the housing around the tubular member to attract the valve plunger away from the resilient seat when the solenoid is energized. The plunger has a spring member within the fluid passageway to bias the plunger against the resilient valve seat when the solenoid is not energized.
The foregoing and other objects, features and advan-" tages of the invention will be apparent from the following more particular description of two embodiments of the invention as illustrated in the accompanying drawings in which:
FIG. 1 is a cross-sectional view in elevation of a first See embodiment of the invention adapted for stationary installation in an automatic system;
FIG. 2 is a cross-sectional view in elevation of a second embodiment of the invention adapted for hand-held use; and
FIGURE 3 is a perspective view of the valve plunger and biasing spring.
The invention will be understood more readily by making reference to FIG. 1 of the drawings which is a crosssectional view of an assembled gun construction in accordance with the features of the invention. The gun comprises a cylinder member 1 having end closure members 3 and 5. The end closure members 3 and 5 are held in assembled relationship against cylinder 1 by means of a tubular member 7 which has external threads on each end and an internal fluid passageway 17. One end of the tubular member 7 is threaded into the end closure 3 to form a fluid chamber indicated generally by the numeral 9. An appropriate fluid seal such as gasket 11 is provided between tubular member 7 and end closure 3.
Fluid chamber 9 has a valve plunger 13 slidably mounted therein. The valve plunger 13 has an internal fluid passageway 15 which is in substantial alignment with the internal fluid passageway 17 of tubular member 7. The fluid chamber 9 has an aperture 19 in which is mounted a resilient valve insert 21. The valve plunger 13 is provided with a tapered tip 23 which provides the closure for the resilient valve insert 21. Tapered tip 23 is normally biased against resilient valve insert 21 to close completely aperture 19 by means of a spring 25 located within the internal passageway 15 of valve plunger 13.
A solenoid 27 is mounted within hollow portion 29 of the housing concentrically with cylinder member 1 and tubular member 7. An electrical connecting cable 31 is connected to soleoid 27 and passes through aperture 23 in end closure 5 to an appropriate external source of electrical power. Easy access is provided for the electrical assembly since nuts 35 and 37 provide the only retaining means for end closure 5, cylinder member 1, solenoid 27 and solenoid retaining plate 39. Also, since the hollow portion 29 provides ample internal space, the electrical connecting cable 31 may be connected to solenoid 27 such that all connections are located within the housing itself.
Fluid chamber 9 may be provided with an additional aperture 41 which serves as a by-pass connection for a fluid supply line illustrated diagrammatically by numeral 43. When a bypass line is utilized a suitable by-pass control arrangement shown generally at 45 and a supply pump arrangement 47 are connected in closed circuit with the spray gun so that a continuous circulation of fluid can be maintained when the gun is not operating. This prevents the settling of any sediment in the fluid and clogging of the apparatus.
The gun shown in FIG. 1 is designed for an automatic installation to be operated at a remote location. The gun is held in position to spray articles, which may be moving past the gun on an assembly conveyor, by means of mounting post 49 which is threaded into end closure 3. Appropriate positioning linkages (not shown) may be connected to mounting post 49 to allow the positioning of the gun in any desired manner.
In operation the supply pump 47 supplies fluid under pressure to the gun through internal fluid passageway 17 of tubular member 7. The operating pressure of the system may be 3000 psi. which is very high compared to conventional systems. The valve plunger 13 is biased by spring 25 so that tapered tip 23 engages the resilient valve insert seat 21 to close oil aperture 19. When it is desired to begin the spring operation, solenoid 27 is energized from a remote location through electrical connecting cable 31. The energizing of solenoid 27 causes valve plunger 13 to be attracted away from aperture 19, and the tapered tip 23 is removed from engagement with the resilient valve insert 21, thereby opening aperture 19. The gun is designed so that a very small movement of valve plunger 13 in either direction is all that is required to open and close aperture 19. The use of the tapered tip 23 in combination with resilient valve seat insert 21 provides a positive sealing action. This positive sealing action, together with the very short plunger travel, enables rapid actuation of the gun and insures positive shut off.
The valve action of the present spray gun has op-' erational advantages over conventional valve actions because of the short, but rapid, plunger travel. A typical airless spray gun has a relatively slower moving valve. In high pressure operation the slower moving valve of the prior art would permit an initial escape of fluid before it is fully open. The reverse action would occur when closing. Any change in size in the orifice results in a change of pressure on the fluid, and even though it is of very short duration, it is reflected in the spray pattern by a change in the degree of atomization. This produces a spattering efiect at the start and finish of the spray. The apparatus of the present invention is not subject to these undesirable features.
' When solenoid 27 is operated and aperture 1.9 is opened, the fluid under pressure from supply pump 47 is forced in a straight line through the gun assembly and out nozzle structure 51, which is of conventional design. The high pressure flow of fluid through nozzle structure 51 causes atomization of the fluid and the formation of a suitable spray pattern in accordance with features which are well known in the art. When valve plunger 13 is closed upon de-energizing the solenoid, by-pass control 45 is opened to allow circulation of the fluid through the system and maintain the apparatus in condition for immediate operation. Since the fluid passes through solenoid 27 at all times, the heat generated by current through solenoid 27 is quickly dissipated.
When the apparatus is to be cleaned, a cleaning fluid is substituted for the working fluid normally supplied, and the pump 47 forces the cleaning fluid through the system. Because of the straight line arrangement of fluid flow, there is no opportunity for fluid to collect in outof-the-way recesses present in conventional gun arrangements. Therefore, the spring 25, plunger 13 and all passageways are cleared of any residue by the fl-ow of cleaning therethroug'h. This marks a substantial improvement over conventional guns in which the valve plunger and biasing spring are normally located out of the line of flow of fluid, and residue collects readily to impair the spring and valve action.
A second embodiment of the invention is shown in FIG. 2 where corresponding-parts have been given the same numerals as those appearing in FIG. 1. This gun is designed for hand-held operation. The end closure members 3' and are similar to end closure members 3 and 5 of FIG. 1, except that the apertures for by-pass control, mounting posts and electrical connecting cable are not required. The cylinder member 1' forming the body of the gun apparatus has an integral handle member 53 which is hollow and contains a battery 55. A pair of contacts 57, 59 are operated by a finger-actuated plunger 61, which is biased by spring 63. Access to the battery 55 for replacement purposes may be gained by means of a removable plate (not shown).
The operation of the gun of FIG. 2 is identical to the operation of the embodiment shown in FIG. 1 except that the solenoid is actuated by the operator holding the gun, instead of at a remote location. In this case it is 4! not necessary to provide a by-pass fluid arrangement, since continuous operation over long periods of time is not contemplated in a hand apparatus.
From the foregoing description it will be appreciated that the present invention has provided a spray gun for high pressure spraying which will be simple and fast in operation, will have a minimum number of parts and will be cleaned easily both internally and externally. The housing structure for the electrical solenoid provides a means of easily and reliably connecting the solenoid to a power supply Without hazardous and unsightly external electrical connections. The fast action and positive feeding of the valve enable this device to be used in applications where precise control is required.
While the invention has been shown and described with particular reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.
What is claimed is:
An airless spray gun for fluids comprising a cylinder having first and second end closure members forming a hollow housing, a tubular member having a first internal fluid passageway mounted concentrically with said cylinder to define a hollow annular space within said cylinder, one end of said tubular member being threaded into said first closure member to define a fluid chamber and the other end being adapted to be connected to a source of fluid supply, a first aperture within said fluid within said second closure member for making electrical connections to said solenoid solely within said cylinder, and a third fluid passageway communicating with said fluid chamber to provide a bypass path for said fluid to insure continuous fluid circulation when said gun is not in operation, said second internal fluid passageway in said valve plunger being in substantial alignment with said first aperture and said first internal fluid passageway in said tubular member, whereby the flow of fluid through said gun is substantially in a straight line passing through said first and second fluid passageways and over said spring member to insure rapid and thorough cleaning of the moving plunger and spring member.
References Cited by the Examiner UNITED STATES PATENTS 1,504,773 8/24 Marston 239585 1,664,616 4/28 French 239585 1,792,929 2/ 31 Remey 239-585 2,305,290 12/42 Fuscaldo 239- 2,540,357 2/51 Stanley 239332 2,743,137 4/56 Wilson 239- 2,999,646 9/61 Wagner 239--526 3,067,954 12/62 Hooper 239-582 FOREIGN PATENTS 217,249 9/ 61 Austria.
672,5 73 3 39 Germany.
852,481 10/60 Great Britain.
M. HENSON WOOD, JR., Primary Examiner.
EVERETT W. KIRBY, Examiner,