Fluid sprinkling – spraying – and diffusing – Flow line or nozzle attached or carried handgrip or handle – Pistol grip type
Reexamination Certificate
2000-04-07
2001-08-21
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Flow line or nozzle attached or carried handgrip or handle
Pistol grip type
C239S583000, C239S600000, C239SDIG001, C251S335200
Reexamination Certificate
active
06276616
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to spray guns for paint and other the liquids and particularly to airless or hydrostatic atomization types of spray guns.
2. Description of the Prior Art
Typical spray guns of the airless or hydrostatic type, as exemplified by U.S. Pat. No. 4,245,784, eject the fluid through at least one central channel of a discharge nozzle where the fluid is atomized into particles which are sprayed in a conical or fan shaped pattern. In some spray guns the fluid passageway or passageways are directed tangentially into a circular chamber situated immediately upstream of the discharge nozzle to impose a circular or whirling motion around the discharge axis of the spray pattern. In other spray guns the fluid is electrostatically charged at the time the spray pattern is established, as seen in additional prior art references, Canadian patent Nos. 965,943 of Patrick D. Shaffer and 972,949 assigned to Graco, Inc.
A typical airless spray gun has a pistol grip handle including a trigger and valve for controlling liquid flow and an adjustment element for varying the spray patterns and/or the degree of atomization. Such a spray gun has a principal fluid flow passage leading to the discharge nozzle, with a needle valve stem situated centrally in this passage and terminating in a ball or other valve closure element that engages a valve seat. A helical coil spring is situated within this fluid flow passage and surrounding the valve stem for biasing the valve to a closed position unless and until it is opened by the trigger.
Additional prior art references illustrating various spray guns include U.S. Pat. No. 4,572,438 to Traylor, U.S. Pat. No. 4,713,257 to Luttermoller, U.S. Pat. No. 4,750,676 to Huber, et al., U.S. Pat. No. 5,725,161 to Hartle, and U.S. Pat. No. 5,803,372 to Weinstein, et al.
While spray guns of these types are well known and relatively successful, they have various drawbacks as follows. Firstly, the spring and needle valve stem reside in the fluid flow passage where paint particles of the flowing fluid can dry and jam the apparatus or later become dislodged and bleed into subsequently used paint of a different color, or flake off and clog the discharge nozzle. Secondly, the basic or typical airless spray gun has a considerable number of components in a relatively complex assembly, such that it is quite difficult and time consuming for users to maintain and/or disassemble and repair the apparatus.
OBJECTS AND SUMMARY OF THE INVENTION
The new invention provides an airless spray gun with a needle loading assembly, which might also be called valve stem mounting assembly, that is easily and very quickly removable and/or replaceable, and furthermore is easy and economical to manufacture. This has been achieved by the design of a removable assembly formed as a cartridge that includes a housing, the valve stem, a spring sub-assembly for biasing the stem in the downstream direction, a valve seal element at the distal end of the valve stem, and a U-cup fluid seal element downstream of the spring to prevent fluid from reaching the area of the spring and the portion of the valve stem surrounded by the spring.
In the spray gun of the new invention the entire cartridge assembly is removed by a simple unscrewing phase and then repaired or replaced. Obviously, reassembly is essentially as easy as disassembly. It has been found that the entire disassembly can be accomplished with two adjustable wrenches in about 90 seconds, which is a great advantage over prior art spray guns.
This ability to disassemble so easily and quickly has been achieved in large part because of the simplicity incorporated into the design of this removable cartridge, and this is made possible because the paint or other fluid no longer travels along the needle valve stem and the adjacent spring. As seen in the attached drawings of a preferred embodiment of this invention, the liquid flow path is directed to a chamber downstream of the area where the valve stem is engaged by the spring. A seal adjacent and upstream of this chamber bars fluid from flowing upstream to the area of the spring, the chamber surrounding the spring and the portion of the valve stem surrounded by the spring. Also with this design the location along the length of the valve stem of engagement with the spring is still relatively near the distal end of the stem which engages and seals with the valve seat. In spray guns where the spring engages the valve stem at a great distance from the sealing end there is substantially greater risk of bending or breaking the stem. Thus, this design retains the benefit of applying a spring force relatively close to the valve, while not exposing the spring and associated parts to the paint itself.
It is thus an object of this invention to make disassembly, cleaning, repair, and reassembly very easy and quick, and to provide a needle valve stem and spring subassembly that is easy and economical to manufacture.
An additional object is to provide an airless spray gun where the paint or the fluid to be sprayed is detoured away from the spring, the needle valve stem and the surrounding chamber.
The present invention is believed to be applicable to various types of spray guns besides airless, including gravity feed, suction feed and pressure feed, and to electrostatically charged spray guns. In all these applications the spray fluid is directed to the downstream portion of the needle valve stem instead of to the upstream part and along the length of the stem.
REFERENCES:
patent: 1969205 (1934-08-01), Carr et al.
patent: 3633828 (1972-01-01), Larson
patent: 4245784 (1981-01-01), Garcin
patent: 4560109 (1985-12-01), Teruyuki et al.
patent: 4572438 (1986-02-01), Traylor
patent: 4713257 (1987-12-01), Luttermoller
patent: 4750676 (1988-06-01), Huber et al.
patent: 5615804 (1997-04-01), Brown
patent: 5669557 (1997-09-01), Barrett et al.
patent: 5695120 (1997-12-01), Kingsford
patent: 5725161 (1998-03-01), Hartle
patent: 5803372 (1998-09-01), Weinstein et al.
patent: 972949 (1975-08-01), None
Ganey Steven J.
Illinois Tool Works Inc.
Pitney Hardin Kipp & Szuch LLP
Scherbel David A.
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