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EP-4212249-B1 - SPRAYING APPARATUS WITH PILOT AIR CONTROL

EP4212249B1EP 4212249 B1EP4212249 B1EP 4212249B1EP-4212249-B1

Inventors

  • MOLITOR, Stefan

Dates

Publication Date
20260513
Application Date
20230112

Claims (14)

  1. Spraying apparatus (10, 30, 40) with air atomisation and pneumatic drive, comprising: at least one air valve (102, 302, 362) for controlling a spray air flow through the spraying apparatus (10, 30, 40), at least one media valve (112, 212, 312) for controlling a media flow through the spraying apparatus (10, 30, 40), at least one first pneumatically actuated drive piston (110, 310, 370) for actuating the at least one air valve (102, 302, 362) and at least one second pneumatically actuated drive piston (130, 230, 330) for actuating the at least one media valve (112, 212, 312), characterised in that a first piston chamber associated with the at least one first drive piston and a second piston chamber associated with the at least one second drive piston are directly fluidly connected to each other, so that the control air can always flow between the first and second piston chambers and pressure equalisation between the first piston chamber and the second piston chamber can take place automatically, and have a common control air supply.
  2. Spraying apparatus (10, 30, 40) according to claim 1, characterised in that the at least one first and the at least one second drive piston are mechanically decoupled.
  3. Spraying apparatus (10, 30, 40) according to one of the preceding claims, characterised in that the air valve has a first closure member, preferably a valve cone, mechanically coupled to the at least one first drive piston, and a valve seat.
  4. Spraying apparatus (10, 30, 40) according to claim 3, characterised by a first preload spring acting on the at least one first drive piston against its direction of action, wherein the at least one first drive piston is linearly movable back and forth between a rest position and an operating position and wherein the first preload spring presses the first closure member against the first valve seat via the at least one first drive piston.
  5. Spraying apparatus (10, 30, 40) according to one of the preceding claims, characterised in that the media valve has a second closure member, preferably a valve needle, mechanically coupled to the at least one second drive piston, and a second valve seat.
  6. Spraying apparatus (10, 30, 40) according to claim 5, characterised by a second preload spring acting on the at least one second drive piston against its direction of action, wherein the at least one second drive piston is linearly movable back and forth between a rest position and an operating position, and wherein the second preload spring presses the second closure member against the second valve seat via the at least one second drive piston.
  7. Spraying apparatus (10, 30, 40) according to claim 1, characterised in that a restrictor is arranged in the fluid connection between the first piston chamber and the second piston chamber.
  8. Spraying apparatus (10, 30, 40) according to claim 7, characterised in that the restrictor is formed by a second throttle check valve.
  9. Spraying apparatus (10, 30, 40) according to claim 1, characterised in that the at least one first drive piston and the at least one second drive piston are arranged to act in opposite directions along a common longitudinal axis and that the first piston chamber and the second piston chamber are formed by a common piston chamber.
  10. Spraying apparatus (10, 30, 40) according to claims 4 and 6, characterised in that the first preload spring and the second preload spring are designed such that the first preload spring presses, in the rest position, against the at least one first drive piston with a lower preload than the second preload spring presses, in the rest position, against the at least one second drive piston.
  11. Spraying apparatus (10, 30, 40) according to claim 10, characterised in that the first preload spring has a lower spring constant than the second preload spring.
  12. Spraying apparatus (10, 30, 40) according to claim 1, characterised in that a first throttle check valve (378) is arranged upstream of the first piston chamber (313) on the inlet side.
  13. Spraying apparatus (10, 30, 40) according to one of the preceding claims, characterised by at least two air valves (302, 362) for controlling a spray air flow through the spraying apparatus (40), wherein at least two first pneumatically actuated drive pistons (310, 370) are provided for actuating the at least two air valves (302, 362).
  14. Spraying apparatus (10, 30, 40) according to one of the preceding claims, characterised by at least two media valves (112, 212, 312) for controlling a media flow through the spraying apparatus (40), wherein at least two second pneumatically actuated drive pistons (130, 230, 330) are provided for actuating the at least two media valves (112, 212, 312).

Description

The present invention relates to a spraying apparatus with air atomization and pneumatic drive. Spray guns are used to apply liquid, pasty, or powdered media to surfaces, creating a coating. The medium is atomized through a nozzle and directed towards the surface, gradually forming a thickening coating. Examples of media include varnishes, paints, water-based coating systems, adhesives, oils, and release agents, which are fed to the spray gun under pressure. When a media valve opens, the medium exits the nozzle along a longitudinal axis through an orifice. Depending on the design of the spray gun, the medium is atomized in different ways. Some spray guns atomize the medium immediately upon exiting due to high media pressure (on the order of several hundred bar overpressure) and the geometry of the media opening, resulting in a spray jet consisting of a finely dispersed, uniformly distributed media mist. No atomizing air is required in this process. This technology is therefore also referred to as "airless." Currently, such spray guns are known to operate with media overpressures of up to 300 bar. In air-atomizing spray guns, atomizing air is supplied to the nozzle at high pressure along with the medium. When an air valve is opened, the atomizing air exits the nozzle through air vents and then strikes the medium exiting the medium orifice, atomizing it to form a spray jet consisting of a finely dispersed, uniform mist. The medium pressure is typically significantly lower than in airless atomization, ranging from 1 to 10 bar overpressure. Currently, spray guns operating at medium overpressures of up to 12 bar are known. Also included in this category of air-atomizing spray guns are hybrid forms of both techniques, in which "airless" atomization initially occurs due to high media pressures and a small media opening. This atomization is further supported by atomizing air, which exits through air openings in the nozzle and then encounters the already atomized media mist. Currently, such spray guns are known to operate with media overpressures of up to 150 bar. Furthermore, spray guns are known that additionally feature a channel arrangement for supplying so-called forming air, which is used to adjust or modify the geometry of the spray jet. The forming air is also referred to as horn air because, in the area of the nozzle, two horns with outlets are usually formed, from which the forming air exits at an acute angle to the longitudinal axis and shapes the spray jet. The forming air is generally supplied separately from the atomizing air and with different parameters (pressure and volume flow). Atomizing air and molding air are combined here under the term spray air. The term "spraying apparatus" encompasses all applications, from hand-held spray guns to fully automated robotic systems. The coating medium is applied to the surface by, for example, an operator manually guiding the spray gun over the surface to be coated in manual applications, or by a robot fully automatically triggering the spraying process at the designated point in automated applications. DE 38 21 817 A1 and DE 196 54 514 A1 reveal spraying devices from the state of the art. Air-atomizing spray guns usually also have a pre-air function. For example, the following text is included. DE 808 538 A Reference is made to a spray gun known in which a media valve and an air valve are arranged coaxially one behind the other, which offers advantages with regard to the maintenance and care of the spray gun. The valves are connected in such a way that they can be adjusted independently of each other. It is therefore particularly possible to adjust the stroke of the media valve relative to that of the air valve so that the air valve opens before the media valve, thereby generating a so-called pre-air supply. This ensures that the exiting medium is atomized uniformly from the very first exit and that no material accumulates at the nozzle, which could cause an irregular spray pattern. Conversely, at the end of the spraying process, the media valve is closed first for the same reason, with a post-air supply similarly preventing material accumulation at the nozzle. The [reference to the text is missing from the original German text]. DE 808 538 A The spray gun presented is mechanically operated, meaning that the force to open the valves must be applied manually using a trigger lever. In addition to mechanically operated spray guns, there are also those operated by pneumatic control. This pneumatic control actuates one or more valves for the medium and/or the spray air, referred to here as the "pneumatic drive." In manual applications, the pneumatic control facilitates operation because the work of opening the valve(s) is performed by the pneumatic control; it is also essential for automated operation. A hand-operated spray gun with pneumatic control is described, for example, in the following document. DE 20 004 087 U1 known. An automatically operated spray gun w