Liquid purification or separation – With repair or assembling means
Reexamination Certificate
2001-06-12
2002-12-03
Popovics, Robert J. (Department: 1724)
Liquid purification or separation
With repair or assembling means
C210S251000, C210S416100, C210S460000, C210S483000, C210S497010, C210S499000, C239S149000, C239S331000, C239S332000, C239S525000, C239SDIG001
Reexamination Certificate
active
06488846
ABSTRACT:
TECHNICAL FIELD
This invention relates to a filter system for paint sprayers. The invention is applicable, for example, to airless paint spraying systems.
BACKGROUND OF THE INVENTION
Airless paint spraying systems conventionally incorporate a pick-up or siphon tube which has a lower end positionable in a five gallon can or other container for paint. During operation the contents of the container are vacuum drawn up through the tube and pumped to a spray gun.
It is well known to position filters at the immersed ends of paint sprayer intake tubes to prevent debris in the paint from entering the tubes.
U.S. Pat. No. 5,567,323, issued Oct. 22, 1996, notes the common usage of multiple in-line filters to filter paint multiple times during the process of moving the paint from the paint container, through an airless spraying system, and onto a surface and/or object to be painted. Such filters frequently become clogged with debris, causing operating down-time to determine the location or locations of the clogs and eliminating them through replacement of the clogged filters.
As is also pointed out in the text of U.S. Pat. No. 5,567,323, it is known to employ a so-called rock catcher formed of a loose, heavy wire mesh at the intake of a sprayer, such device designed primarily to eliminate larger debris from the paint. It is known to cover the rock catcher with a fine mesh nylon net having a drawstring to secure to the rock catcher. Rock catchers of the type referenced in U.S. Pat. No. 5,567,323 become fouled quite readily and are difficult to remove from the intake tube when the paint dries. Furthermore, they do not operate to control flow of paint into the interior thereof where the sprayer intake is located. Such devices are also expensive. Fine mesh bags employed as covers detract from the efficiency of the sprayer, particularly in sprayers which rely on a vacuum to draw the paint into the intake tube. It will be appreciated that vacuum intakes of this type provide for a pressure differential on the paint entering the system that is limited to atmospheric pressure. Thus, a fine mesh net or bag will quickly impede paint flow and clog completely in many instances. This causes the airless sprayer to vaporize paint and become inoperative. Furthermore, fine mesh filter components or covers do not readily lend themselves to cleaning for reuse and can readily distort under pressure to enter openings of the rock catcher and clog them as well. The rock catcher and bag can fuse together and become difficult to separate, particularly when some paint drying has occurred. Also, drawstrings are notoriously difficult to untie or loosen when impregnated with paint and removal of the outer bag is desired, necessitating destruction of the bag in some cases so that it cannot be reused.
The intake filter which is the subject of U.S. Pat. No. 5,567,323 is of unitary construction, incorporating a filter element in the form of a very fine wire mesh formed into an accordian shape about the periphery thereof. The fine wire mesh accordianed filter is disposed about a rigid support having openings or apertures therein. End caps maintain the entire filter together as a unit. The text of U.S. Pat. No. 5,567,323 makes reference to the fact that the structure is such as to maintain the accordian shape of the accordian wire mesh
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against the “about 2,000 to about 5,000 psi” pull of the airless paint sprayer pump with which the filter is associated. In reality, however, there are no forces of such magnitude applied at an intake of a airless paint sprayer since the maximum pressure on the paint is limited to atmospheric pressure. In such a situation, the use of a fine accordianed wire mesh in a filter as suggested by U.S. Pat. No. 5,567,323 will negatively impact operation of the device and result in plugging on a frequent basis. While the arrangement of U.S. Pat. No. 5,567,323 is alleged to be capable of being flushed out and cleaned for reuse, this is not a simple procedure and requires disassembling and reassembling multiple components of the unit.
It is also known to employ foraminous cups at the ends of intake tubes. These devices also foul quite readily and become deformed and damaged during use.
Other known arrangements are those of the following patents: U.S. Pat. No. 5,842,639, issued Dec. 1, 1998, U.S. Pat. No. 4,878,930, issued Nov. 7, 1989, and U.S. Pat. No. 5,252,210, issued Oct. 12, 1993. These patents do not teach or suggest the combination of structural elements and cooperative relationships disclosed and claimed herein.
DISCLOSURE OF INVENTION
The present invention relates to a filter system for paint sprayers characterized by its relative low cost, efficiency and effectiveness. The filter system incorporates a reusable filter that can be readily attached to or detached from a rigid paint flow control and filter support frame mounted at the distal or intake end of a paint sprayer intake tube. The frame and filter are cooperative when the filter is installed on the frame to remove debris from paint prior to drawing of the paint into the intake tube during the spraying operation. When cleaning is desired, the filter can be quickly detached from the frame and the cleaning operation carried out. Typically, cleaning is accomplished quite simply by applying water or other liquid to the separated frame and screen. Reinstallation of the filter is just as easy.
The combination of the system includes a paint sprayer intake tube having an intake tube open distal end for immersion in paint in a container. For the purposes of this application, the term “paint” is to be broadly construed and covers not only paint per se but also stains and other types of sprayable liquids.
The combination also includes a rigid frame attached to the paint sprayer intake tube. The rigid frame defines a frame interior communicating with the open distal end and having a peripheral wall defining a plurality of frame openings communicating with the frame interior.
A reusable filter surrounds the peripheral wall of the rigid frame and comprises a flexible screen releasably connected to the rigid frame. The screen defines screen openings in fluid flow communication with the frame openings. The screen openings are smaller than the frame openings.
The sizes of the screen openings and the frame openings fall within selected ranges.
The frame has a cylindrical configuration and the flexible screen is of non-accordianed construction, has a cylindrical configuration and further has an inner screen surface in face-to-face contact with the peripheral wall of the rigid frame over substantially the full extent of the peripheral wall of the frame.
The flexible screen includes screen edges and synthetic hook and eye connector strips are attached to the flexible screen at at least some of the edges, adjacent connector strips being in engagement to maintain the flexible screen in frictional engagement with the peripheral wall of the rigid frame to maintain the flexible screen in position on the rigid frame.
Other features, advantages and objects of the present invention will become apparent with reference to the following description and accompanying drawings.
REFERENCES:
patent: 4003504 (1977-01-01), Johnson et al.
patent: 4785997 (1988-11-01), Liska et al.
patent: 4878930 (1989-11-01), Manniso et al.
patent: D310117 (1990-08-01), Mariol
patent: 5252210 (1993-10-01), Kessel
patent: 5567323 (1996-10-01), Harrison, Jr.
patent: D384676 (1997-10-01), Cyphers et al.
patent: 5725364 (1998-03-01), Mirazita
patent: 5769321 (1998-06-01), Cyphers
patent: 5842639 (1998-12-01), Walker
patent: 5947137 (1999-09-01), Sheafer
patent: 6183224 (2001-02-01), Conatser
Lampe Thomas R.
Popovics Robert J.
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