SPRAY GUN

Abstract: Spray gun for mixing and spraying of two media, and of the type incorporating a valve for one medium each. The two valves are provided one inside the other one and designed to be axially displaceable in a housing and relative to each other to and from one valve seat each against the action of a spring. The valves are together influenceable by an external force.

Description: SPRAY GUN The present invention refers to a spray gun for mixing and spraying of two media, and of the type incorporating a valve for one medium each. Background and problem of the invention. Spray guns of the type mentioned above are earlier known, which have two separate valves for one medium each and positioned at some distance from each other and a common mixing chamber. A drawback with these is that when the two media react with each other the orifices of the valves will be clogged up and for preventing this is required a careful cleaning at every interruption of the spraying operation. A further drawback is that the spray gun will become bulky, is more difficult to handle, has many movable components and therefore requires more maintenance and is more expensive to manufacture than spray guns for one medium only. Purpose of the invention and solution of the problem. The purpose of the invention is to provide a spray gun, which: .is easy to clean, by wiping it off .prevents contamination of the valve orifices to a large extent, .is as easy to handle as spray guns for one medium only, .has a few movable components, .requires a minimum of maintenance, .is worth its price. These tasks have been solved in that the two valves are provided one inside the other and designed axially displaceable in a housing and relative to each other to and from one valve seat each against the action of a spring, and that the valves are actuatable together by an external force. Description of the drawings Hereinafter the invention will be further described as an embodiment with reference to the accompanying drawings . Fig. 1 shows a section through a spray gun according to the invention in closed, passive position. Fig. 2 shows in bigger scale a section through the intermediate portion of the spray gun, with the valves in open, active position. Fig. 2a is a partial enlargement of the encircled portion 2a from Fig. 2. Fig. 2b is a partial enlargement of the encircled portion 2b from Fig. 2. Description of embodiment The spray gun according to the invention consists of a central housing 11, which at its forward part is equipped with a spraying nozzle 12 and at its rearmost portion with a servo mechanism 13. The central housing 11 incorporates two valves 14 and 15, the inner one 15 of which is provided within the other, outer valve 14. The housing also incorporates a handle 16 and in front of this a trigger 17 in the form of a two-armed lever, which is pivotable about a shaft 18. In the upper part of the housing is also provided a valve arrangement 19 for controlling the servo mechanism 13. The outer valve 14, which is axially displaceable in the housing 11 consists of a sleeve 20, which passes over into a coaxial tube 21, which extends into the spraying nozzle 12. A protective bushing 22 is thread over the tube 21, and the forward tapering end 23 of which cooperates with a valve seat 24 in the housing 11. At the front end of the tube is provided a non-return valve 25, which opens at a pressure inside the tube. The protective bushing 22 is surrounded by an annular channel 30, which communicates with a supply conduit 31 for a first medium, e.g. polyester. At the transition between the tube 21 and the sleeve 20 is provided a valve seat 26 in the latter, which cooperates with the end surface of the valve body 27 of the inner valve 15. This is constituted by a tube 28, the forward end of which is closed, but provided with lateral openings 29, which communicate with a second annular channel 32, which can be brought in communication with the interior channel 33 of the tube 21, when the valve body 27 is displaced in a direction away from its seat 26 and the opening of the channel 33 is exposed. The inner valve 15, which is axially displaceable in the sleeve 20 of the outer valve 14, passes over with its tubular valve body 28 into a bush 34, which is guided inside the sleeve 20. The inner channel 36 of the tube 28 opens at this bushing, and a supply conduit 37 for a second medium, e.g. a hardening agent is connected to this channel. A piston rod 39 of a piston 40, forming part of the servo mechanism 13 and being subjected to load by a pressure spring 38 is also attached to the bushing 34. A conduit 35 for pressurized air is also connectable to the housing 11, and which supplies pressurized air to a valve stem 41 equipped with two valve bodies 42 and 43, one of which always closes against a valve seat, whereas the other one is open. The position of the valve stem is controlled by means of the trigger 17. When the trigger is acted upon, the valve body 42 opens the passage to an air conduit 44, which leads the pressurized air to the forward side of the piston 40. The piston rod 39 thereby will be subjected to a tensile force acting against the action of the spring 38. The tensile force is transferred to the bushing 34, whereby the entire valve package consisting of the outer and the inner valves 14, 15 is displaced against a stop 46, such as shown in Fig. 2 and 2a. In this stage the two valves 14, 15 form an interconnected unit, due to the fact that the second medium contained in the annular slot 32 and the channel 36 is under pressure. In this position the passage beyond the valve seat 24 is opened, thus that the first medium can flow from the supply conduit 31 to the connecting channel 45 of the spray nozzle 12. This channel is designed as a mixing chamber or mixing channel equipped with not shown, for instance screw-shaped, mixing members. At continued supply of pressurized air to the piston 40 the passage beyond the valve seat 26 will be opened, thus that the second medium can flow from the annular slot 32 to the inner channel 33 of the tube 21 and further to the nonreturn valve 25, which is thereby opened. Thereby the second medium will reach the mixing chamber 45 and an intimate mixing of the two media can take place. As the outlet opening for the second medium at 25 is situated somewhat in front of the outlet openings at 24 for the first medium and the first medium always is discharged first, there will not be any contamination at these outlet openings 24. The cleaning then can be limited to wiping off the non-return valve 25, after the spraying nozzle 12 has been screwed off. List over reference numerals 11 housing 12 spraying nozzle 13 servo mechanism 14 outer valve 15 inner valve 16 handle 17 trigger/lever 18 shaft 19 valve arrangement 20 sleeve 21 tube 22 protective bushing 23 tapering end 24 valve seat 25 non-return valve 26 valve seat 27 valve body 28 tube 29 opening 30 1st annular channel 31 supply conduit 32 2nd annular channel 33 inner channel 34 bushing 35 conduit for pressurized air 36 inner channel 37 supply conduit 38 pressure spring 39 piston rod 40 piston 41 valve stem 42 valve body 43 valve body 44 air conduit 45 connecting channel/mixing chamber 46 stop

Claims: Claims 1. A spray gun for mixing and spraying of two media, and of the type incorporating a valve (14, 15) for one medium each, c h a r a c t e r i z e d t h e r e i n, that the two valves (14, 15) are provided one inside the other and designed axially displaceable in a housing (11) and relative to each other to and from one valve seat (24, 26) each, against the action of a spring (38), and that the valves together are influenceable by an external force . 2. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the valve seat (26) of the inner valve (15) is provided in the outer valve (14), the valve seat (24) of which is provided in the housing (11). 3. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the inner and outer valves (14, 15) during the initial displacement motion are interconnected hydraulically, with the valve body (27) of the inner valve (15) in closed position. 4. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the external force is constituted by a pneumatically actuatable piston (40) , the piston rod (39) of which is connected to the valve body (27, 28) of the inner valve (15) , which is displaceable in the outer valve, and that the axial displaceability of the outer valve (14) is limited by a stop (46) in the housing (11) and that the valve body (27, 28) of the inner valve (15) is displaceable a little further under opening of the inner valve. 5. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that a non-return valve (25) , which can be opened by the medium, is provided at the orifice of the inner valve (15) . 6. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the orifice of one of the valves is axially spaced from the orifice of the other valve. 7. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the orifices of both valves are arranged to open in a common mixing chamber/channel (45) . 8. A spray gun as claimed in claim 1, c h a r a c t e r i z e d t h e r e i n, that the movement of the pneumatic piston (40) is controlled by a valve stem (41) actuatable by the trigger (17) of the spray gun, and which is adapted in one of its end positions to close the air supply to the pneumatic piston and simultaneously to open a ventilating opening and vice versa.

Inventors: JOENSSON PEDER, JOENSSON, PEDER
Applicants: APLICATOR SYSTEM AB, JOENSSON PEDER, JOENSSON, PEDER
Application year: 1998
Main classification: B05B7
IPC codes: B05B1, B05B7