Fluid sprinkling – spraying – and diffusing – Processes – Including mixing or combining with air – gas or steam
Reexamination Certificate
1999-07-19
2001-07-24
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Processes
Including mixing or combining with air, gas or steam
C239S008000, C239S011000, C239S067000, C239S069000, C239S290000, C239S296000
Reexamination Certificate
active
06264113
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a fluid spraying system adapted for use within a work environment. In particular, the present invention relates to a fluid spraying system configured to discharge an adhesive on a surface to be coated.
BACKGROUND OF THE INVENTION
It is well known to deliver fluids, such as adhesives, from a spraying system for various purposes. Such known spraying systems are disclosed, for example in U.S. Pat. No. 5,419,491 issued to Breitsprecher on May 30, 1995 titled TWO COMPONENT FLUID SPRAY GUN AND METHOD and in U.S. Pat. No. 5,639,027 issued Jun. 17, 1997 to Fritz titled TWO COMPONENT EXTERNAL MIX SPRAY GUN. Such known spray systems include using air pressure to propel or convey one fluid component and air to propel another fluid component. The two components are mixed and applied to a surface to be coated with the fluids.
One such known spraying system includes a two component external mix spray gun that requires a pneumatically operated valve for delivering a catalyst into pattern shaping air passages in the barrel of the gun. The valve opens in response to pressure created by opening a unitary chamber for a pattern shaping air passage and an atomization air passage. Before opening an adhesive fluid valve for delivering an adhesive of such known gun, a manual trigger operates air valves to provide atomization air and the pattern shaping air. The valve is then opened (prior to the opening of the adhesive fluid valve) in response to an increase in air pressure downstream from the air valves (i.e., in response to the operation of the trigger and the presence of the flow of the pattern shaping air) to inject the catalyst into pattern shaping air passages. Then, external to such known spray gun, the catalyst is brought into contact with the adhesive, which is “atomized” by the atomization air and the pattern shaping air. However, a problem with such known guns is that the manual trigger may not fully open the adhesive fluid valve, which may result in an inconsistent and ineffective ratio of the catalyst to the adhesive and “clogging” of the gun.
Another known spraying system includes an air-operated fluid spray gun for mixing multiple fluids together almost simultaneously to deposit the mixture on a surface. Such mixing and deposition is accomplished by first directing an atomized stream of adhesive fluid axially out of the end of the barrel of the gun and toward the surface to be coated. An atomized stream of activator fluid is then injected generally radially into the adhesive stream so that the activator and adhesive streams mix thoroughly and the mixture is almost simultaneously deposited on the surface. In such known spray guns, the activator fluid is discharged from fluid nozzles. However, a problem with such known spray guns is that the activator is turned on before the adhesive is turned on, which may result in an incorrect ratio of a volume of adhesive to a volume of activator fluid and “clogging” of the gun.
Accordingly, it would be advantageous to provide a fluid spraying system that provides for the independent control of the flow of the various fluids. It would also be advantageous to provide a fluid spraying system that provides for improved atomization of the activator fluid, for example with fan air within the fan air passages of an air cap. It would further be advantageous to provide a fluid spraying system that is intended to be simple to assemble, maintain and service. It would also be advantageous to provide a fluid spraying system that provides a suitable ratio of activator to adhesive. Other advantages of the subject matter recited in the claims will become apparent to those skilled in the art upon review of the specification and the appended claims.
SUMMARY OF THE INVENTION
The present invention relates to a spraying system for delivering a plurality of fluids for applying to a surface. The spraying system includes a nozzle assembly having a fluid tip, a body with a central orifice and a set of orifices radially adjacent to the central orifice, an air cap having a set of passages in communication with a set of orifices and a set of conduits contained at least partially within the set of passages, and a plurality of fluid circuits in communication with the nozzle assembly. One of the fluid circuits is adapted to deliver an adhesive, one of the fluid circuits is adapted to deliver an activator, one of the fluid circuits is adapted to deliver atomization air, and one of the fluid circuits is adapted to deliver fan air from the nozzle assembly. The spraying system also includes a controller that can be switched to an active state upon a which the fluid circuit for atomization air and the fluid circuit for fan air are opened essentially simultaneously, the fluid circuit for the activator is opened and then the fluid circuit for the adhesive is opened, and to an inactive state, upon which the fluid circuit for the adhesive and the fluid circuit for the activator are closed essentially simultaneously, and the fluid circuit for atomization air and the fluid circuit for fan air are closed essentially simultaneously. The adhesive is delivered in a generally axial direction through the central orifice in the body, atomization air to atomize the adhesive is delivered in a generally axial direction through the set of orifices in the body, fan air is delivered into the set of passages in the air cap and in a generally radial direction from the set of orifices in the air cap, and the activator is delivered into the set of passages in the air cap from the set of conduits so that the activator is atomized by fan air within the set of passages in the air cap and delivered from the set of orifices of the air cap, so that a fluid mixing area is provided outside the nozzle assembly in a space ahead of the orifices through which the adhesive and atomization air are delivered.
The present invention also relates to a method to for controlling the fluid circuits in a spraying system for delivering a plurality of fluids for applying to a substrate. The method includes switching a controller to an active state upon a which a fluid circuit for atomization air and a fluid circuit for fan air are opened, opening a fluid circuit for activator and opening a fluid circuit for an adhesive, activating the adhesive with the activator, spraying the activated adhesive on a surface, switching a controller to an inactive state upon which the fluid circuit for the adhesive and the fluid circuit for the activator are closed, purging the system with fan air and atomization air, and closing the fluid circuit for the atomization air and the fluid circuit for the fan air.
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Evans Robin O.
Foley & Lardner
Scherbel David A.
Steelcase Inc.
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