U.S. patent number RE34,608 [Application Number 07/864,484] was granted by the patent office on 1994-05-17 for paint spray gun.
This patent grant is currently assigned to AccuSpray, Inc.. Invention is credited to John W. Hufgard.
United States Patent |
RE34,608 |
Hufgard |
May 17, 1994 |
Paint spray gun
Abstract
An improved spray nozzle for use with air atomizable liquids
wherein the spray pattern created by the atomizing nozzle may be
adjusted from a circular pattern to a flat pattern or alternatively
to an open oval. The open end faces in preselected directions. The
adjustments are capable of occurring during the continuous
operation of the nozzle.
Inventors: |
Hufgard; John W. (Novelty,
OH) |
Assignee: |
AccuSpray, Inc. (Cleveland,
OH)
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Family
ID: |
26798396 |
Appl.
No.: |
07/864,484 |
Filed: |
April 7, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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101563 |
Sep 28, 1987 |
4905905 |
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Reissue of: |
297128 |
Jan 17, 1989 |
04915303 |
Apr 10, 1990 |
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Current U.S.
Class: |
239/300; 239/290;
239/526 |
Current CPC
Class: |
B05B
7/0081 (20130101); B05B 7/0823 (20130101); B05B
7/0815 (20130101) |
Current International
Class: |
B05B
7/02 (20060101); B05B 7/08 (20060101); B05B
7/00 (20060101); B05B 001/28 () |
Field of
Search: |
;239/290,296,297,299,300,301,525,526,527 ;251/309,321
;403/381,388 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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222966 |
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Jul 1959 |
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AU |
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753510 |
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Aug 1944 |
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DE |
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2606008 |
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Aug 1977 |
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DE |
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783021 |
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Jul 1935 |
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FR |
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348141 |
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May 1931 |
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GB |
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496231 |
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Nov 1938 |
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GB |
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736131 |
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Aug 1955 |
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GB |
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2115112 |
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Sep 1983 |
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GB |
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Primary Examiner: Kashnikow; Andres
Assistant Examiner: Trainor; Christopher G.
Attorney, Agent or Firm: Watts, Hoffmann, Fisher &
Heinke
Parent Case Text
This is a continuation-in-part of application Ser. No. 101,563
filed Sept. 28, 1987 .Iadd.now U.S. Pat. No. 4,905,905.Iaddend.,
still pending as of Nov. 28, 1989.
Claims
I claim:
1. A spray gun for use with air atomizable liquid comprising;
means forming an air chamber having an outlet end;
a liquid nozzle valve having a conical taper penetrating said air
chamber and extending to and coaxially aligned with a central
circular aperture in the outlet end of said air chamber;
means for delivering a liquid to said central aperture for
atomization by air exiting said air chamber through said central
aperture;
at least two pattern adjusting nozzles disposed adjacent to the
central aperture of said air chamber;
means for conducting air to said chamber and separate means for
conducting air to said nozzles;
means for adjusting the flow rate of air to said nozzles; and
the outlet end of said air chamber having a converging down stream
frusto-conical shape which terminates at said central aperture,
said liquid nozzle valve including external means combined with
said frusto-conical shape for providing an increasing down stream
cross-sectional area in said air chamber toward said frusto-conical
shape;
said gun being formed as parts bolted together, said parts having
internal passages which are mirror images of each other, said
passages comprising said air conducting means extending from an air
inlet into said gun to said chamber and said nozzles, and when said
parts are bolted together said passages combined to form paths for
air delivered to said air inlet from an air source connected to
said gun, there being no additional passage means in said gun for
conducting said air to said air chamber and said pattern adjusting
nozzles.
2. The gun according to claim 1 wherein each pattern adjusting
nozzle is located in a nozzle ear which projects beyond the plane
of said central aperture.
3. The gun according to claim 2 wherein said adjusting means
includes a rotable valve in said separate air conducting means.
4. The gun according to claim 3 wherein said two pattern adjusting
nozzles are located at diagonally opposite sides of said central
aperture.
5. The gun according to claim 1 wherein said adjusting means
includes a rotable valve in said separate air conducting means.
6. The gun according to claim 1 wherein the means for adjusting the
flow rate of air to the pattern adjusting nozzles comprises a
rotable valve in said passage leading to said nozzles and
configured to selectively open, close and partially open said
passage to receive air from said source.
7. The gun according to claim 1 wherein said two pattern adjusting
nozzles are located on diagonally opposite sides of said central
aperture.
8. The gun according to claim 7 wherein the means for adjusting the
flow rate of air to the pattern adjusting nozzles comprises a
rotable valve in said passage leading to said nozzles and
configured to selectively open, close and partially open said
passage means to receive air from said source.
9. The gun according to claim 2 wherein the means for adjusting the
flow rate of air to the pattern adjusting nozzles comprises a
rotable valve in said passage leading to said nozzles and
configured to selectively open, close and partially open said
passage to receive air from said source.
10. The gun of claim 1 wherein said parts are formed from the
thermoplastic resin.
11. The gun of claim 10 wherein said resin has the physical
characteristics of:
(a) low heat conducting as compared to metals,
(b) easy moldability, and
(c) low solubility to paint solvents.
12. The gun of claim 11 wherein the resin is polyphenylene
sulfide.
13. The gun of claim 12 wherein said flow paths are generally
oval-shaped with dimensions of about 1/4 in..times.1/2 in.
14. The gun of claim 13 wherein the source of air delivered to said
paths is at a pressure in the range not substantially greater than
about 10 psig. and a volume of about 5-60 cfm. .Iadd.
15. A spray gun for use with air atomizable liquid comprising:
a. a gun body forming a manually grippable handle and a spray
directing section projecting from said handle;
b. a liquid flow controlling valve supported by said gun body in
said spray directing section;
c. a chamber defined within said gun body spray directing section
and an aperture defined in a wall of said chamber through which
liquid and atomizing air may be directed;
d. liquid directing means for introducing liquid from a liquid
supply to said liquid flow controlling valve;
e. air directing means for introducing air under pressure from an
air supply to said chamber, said air directing means comprising a
passage through which air flows to said chamber;
f. said liquid flow controlling valve disposed at least partly in
said chamber, liquid from said valve and air from said chamber
interacting so that liquid is atomized and air and atomized liquid
are sprayed away from said aperture; and,
g. trigger means for governing operation of said liquid flow
controlling valve to initiate and terminate an atomized liquid
spray;
h. said gun body comprising first and second body parts each
defining a portion of said handle and spray directing section, each
body part defining:
i. a liquid flow controlling valve engaging structure;
ii. trigger means engaging structure; and,
iii. an air passage wall section; and,
i. connector means for detachably clamping said body parts in an
assembled condition with said liquid flow controlling valve and
said trigger means secured in position relative to each other, said
air passage wall sections hermetically secured in place when said
body parts are clamped, said connector means operable to detach the
gun body parts for enabling access to said liquid flow controlling
valve, said air directing means and said trigger means. .Iaddend.
.Iadd.
16. The spray gun claimed in claim 15 wherein said air directing
means further comprises a pressure fitting by which pressurized air
is delivered from the air supply to the passage, said fitting
engaged and supported by said gun body parts. .Iaddend. .Iadd.
17. The spray gun claimed in claim 16 wherein said pressure fitting
is disposed in said handle remote from said aperture and said
passage extends from said fitting to said chamber. .Iaddend.
.Iadd.18. The spray gun claimed in claim 15 further comprising
spray pattern adjusting means for directing streams of air into
said spray for changing the spray configuration, said spray pattern
adjusting means supplied with air from said air passage. .Iaddend.
.Iadd.19. The spray gun claimed in claim 18 further comprising a
flow path branching from said air passage for delivering air to
said pattern adjusting means, each said gun body part defining a
flow path wall section, said flow path wall sections hermetically
secured in place when said body parts are clamped. .Iaddend.
.Iadd.20. The spray gun claimed in claim 18 further comprising an
air flow controlling valve disposed in said flow path for
adjustably controlling the flow rate of air to said pattern
adjusting means, said air flow controlling valve engaged and
supported by respective retaining surfaces of said body parts when
said body parts are clamped. .Iaddend. .Iadd.21. The spray gun
claimed in claim 20 wherein said air flow controlling valve is
linked to said trigger means so that said pattern adjusting means
operates when said liquid valve operates. .Iaddend. .Iadd.22. The
spray gun claimed in claim 18 wherein each of said gun body parts
is molded to define said passage and flow path wall sections, said
flow path branching from said passage at a location remote from
said chamber, said molded wall sections of said passage and said
flow path directing air flow therethrough with relatively low
turbulence. .Iaddend. .Iadd.23. The spray gun claimed in claim 15
further comprising an air flow controlling valve disposed in said
passage for initiating and interrupting the flow of air to said
chamber, said air flow controlling valve hermetically clamped
between said gun body parts. .Iaddend. .Iadd.24. The spray gun
claimed in claim 15 wherein said gun body parts are clamped
directly into engagement with each other to define said passage,
said parts defining mating tongue and groove sealing elements which
are sealingly engaged when said body parts are clamped. .Iaddend.
.Iadd.25. The spray gun claimed in claim 15 wherein said connector
means comprises a collar member threaded onto said body parts at
said spray directing section, said body parts defining coextending
portions having coordinated threaded surfaces for receiving said
collar. .Iaddend. .Iadd.26. The spray gun claimed in claim 25
wherein said chamber wall is defined by a cap-like member extending
about said coextending body portions, said aperture defined in said
cap-like member and said collar retaining said cap-like member in
position. .Iaddend. .Iadd.27. A spray gun for use with an air
atomizable liquid, comprising a body with handle and spray
directing sections and passages therethrough for the flow of
atomizing air, pattern adjusting air and liquid, the atomizing air
and liquid discharged through an aperture in the spray directing
section, and a trigger for controlling the liquid flow, said body
comprising separate body parts and connector means for detachably
clamping said body parts together, each body part forming part of
each air passage so that when said body parts are clamped together
they form said passages, said clamped body parts providing
structure for receiving air and liquid supply connections.
.Iaddend. .Iadd.28. A spray gun according to claim 27,
characterized by the fact that the passage sections of the body
parts are hermetically sealed. .Iaddend. .Iadd.29. A spray gun
according to claim 27, characterized by the provision of a control
valve for governing the passage of the pattern-adjusting air.
.Iaddend.
.Iadd. A spray gun according to claim 27, characterized by the fact
that the trigger is linked to means for controlling the flow of
air. .Iaddend. .Iadd.31. A spray gun according to claim 27,
characterized by the fact that the body parts are made of
thermoplastic resin. .Iaddend.
Description
FIELD OF THE INVENTION
The invention relates to an improved paint spray gun and nozzle for
adjusting the spray pattern using low pressure and high volume air
for atomizing the paint and controlling the spray pattern.
BACKGROUND OF THE INVENTION
Spray guns and nozzles, especially those used with spray painting
systems, atomize the liquid paint by means of atomizing air which
enters the nozzle area via a chamber which surrounds a fluid
nozzle. The atomizing air is then impinged on the end of the
chamber and exits via a central aperture located at the end of the
chamber. The paint is atomized by the accelerating burst of forward
motion of this air as it exits the nozzle via the aperture. The
initial conventional pattern of the atomized liquid and air mixture
in cross-section is a circle because the exit aperture is
circular.
The term pattern as used herein describes a cross-section of the
atomized cloud of paint droplets in a plane perpendicular to the
direction of the spray from the fluid nozzle. When the compressed
air source for a spray painting apparatus utilizes a high volume,
low pressure compressor, it is conventional for the air exit nozzle
on the spray painting gun to have a central aperture which is
considerably larger than the circumscribed liquid nozzle.
Therefore, the large amount of air utilized in a conventional
nozzle is due to the relative size of the central aperture compared
to that of the liquid nozzle. This excess air, air beyond that
required to atomize the liquid properly, constitutes an energy
waste as well as a pollution problem. The excess air is a pollution
problem since the air in a paint system will tend to carry the
paint solvent. The more air that is used, the more dilute the
solvent, and the more air that must be processed for the removal of
solvents.
Therefore, there is a need for an improved spray nozzle which more
efficiently utilizes the air that it actually receives from the air
source.
The pattern of a spray nozzle is conventionally adjusted by
impinging additional air jets into the original circular pattern at
a location beyond the outlet aperture. A standard design may
include two oppositely directed jets which produce a flat or oval
pattern, and if those jets are very powerful it produces a flat fan
type spray pattern which is many times wider than it is high.
However, in production line spraying, there are needs for other
than such flat or oval patterns, especially when spray painting the
reverse sides of objects or spray painting in an out-of-position
way and also the traditional problem of painting the insides of
angular surfaces.
Therefore, there is also a need for improved pattern control in
spray nozzle systems and the ability to adjust the pattern to other
than flat or oval pattern. It would additionally be desirable if
such adjustments or modifications of the pattern could be achieved
without the necessity of changing the nozzle in use.
Another problem with spray guns is that the air from the compressor
is hot and tends to heat metal parts in the flow path to an extent
that hand held spray guns may burn the operator or at least make
his hand most uncomfortable.
SUMMARY OF THE INVENTION
An improved spray gun according to this invention includes an
atomizing chamber with a central aperture for the exit of atomized
liquid spray. The chamber has a converging frusto-conical surface
approaching the aperture that acts to direct and streamline the
atomizing air.
A fluid nozzle is mounted concentrically with the aperture and the
exterior surface is structured to further direct atomizing air
through the aperture in streamline flow as opposed to turbulent
flow.
Another aspect of the present invention is a pattern adjusting plug
valve which adjusts air flow to the pattern adjusting nozzles which
may be directed at the atomized liquid spray.
The shell of the gun is molded from a resin in two mirror image
halves which are bolted together. The resin will serve as an
insulator because it is a poor heat conductor.
Objects of the invention which are not obvious from the above will
be clear from a review of the drawing and the description of the
preferred embodiments which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
The best mode contemplated in carrying out this invention is
illustrated in the accompanying drawings in which:
FIG. 1 is an elevational view of a paint spray assembly utilizing a
nozzle according to the present invention;
FIG. 2 is a right hand side elevational view of the gun of FIG.
1;
FIG. 3 is a cross-sectional view taken along line 3--3 of the gun
of FIG. 1;
FIG. 4 is a cross-sectional view taken along line 4--4 of the gun
of FIG. 2;
.Iadd.FIG. 4A is an enlarged view of a portion of the gun
illustrated in FIG. 4; .Iaddend.
FIG. 5 is a cross-sectional view taken along line 5--5 of the gun
of FIG. 4;
FIG. 6 is an elevational view of a first alternative form of gun
supplied by a source of high pressure air;
FIG. 7 is a sectional view similar to FIG. 4 but illustrating the
alternative form of gun shown in FIG. 6;
FIG. 8 is a sectional view taken along line 8--8 of FIG. 7; and
FIG. 9 is a sectional view taken along line 9--9 of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings, FIG. 1 shows a paint spray gun 10
which utilizes a nozzle 12 according to the present invention. Any
conventional spray painting gun has a pistol grip type handle on
the body 10 and can optionally have a hook assembly 13 for hanging
the gun after work has been completed or for temporary storage.
An air supply fitting 14 provides a connection to a source 15 of
low pressure, constant high volume compressed air to the spray
painting assembly. Within the body of the spray gun 10 the air
supply is directed along a path to an air chamber adjacent a paint
nozzle as will be explained subsequently.
The paint gun body 10 also has a trigger assembly 20 which is held
in its closed position by a spring 22 in the base of the handle.
Additionally a pull rod 24 is moved by the trigger assembly, pull
rod 24 serving to adjust the flow rate of paint to the nozzle tip
while paint supply fitting 26 provides direct access to the supply
of paint 27.
On the forward end of the body 10 is a nozzle or air cap 28 having
a pair of forwardly projecting ears 30, best seen in FIG. 4. The
cap 28 is mounted in operative position on body 10 and secured in
place by a collar 32 threadedly engaging external threads 34 on the
body.
Turning now to FIG. 4, within the concave nozzle ear faces are
pattern adjusting orifices 44, 46, 48, 50 in fluid communication
with an air passage 57.
FIG. 2 shows the right-hand side elevational view of the gun of
FIG. 1. A knob 54 may be rotated to adjust the compression of
spring 22 as desired. A plug valve 56 may be adjusted manually to
control the flow of air to pattern adjusting ears 30 as will be
explained in more detail subsequently. Line 58 is split between the
two halves forming the body of gun 10.
The body of the gun itself is formed of two molded pieces which are
mirror images of each other. The pieces are formed from Ryton brand
resin, polyphenylene sulfide, in the preferred embodiment but other
suitable resins may be used. Any appropriate resin should be a low
conductor of heat to protect the hand of an operator from heat in
the compressed air from the turbine (up to 180.degree. F.).
Additionally, the resin should be easy to mold into the illustrated
shape and solvent proof to prevent deterioration from paint
solvents or airborne solvents in the atomized air.
A cross-section of the spray nozzle assembly is shown in FIG. 4. In
this view atomizing air chamber 52 serves as a plenum chamber and
is shown with liquid nozzle valve 58 penetrating it, atomizing air
chamber 52 having a central aperture 59 located at its outlet end.
It will be noted that the central aperture 59 has an upstream
converging frusto-conical shaped surface 60. Preferably the
frustoconical shaped surface 60 has a slope not corresponding to
the converging conical end of liquid nozzle valve 58, that is, the
angle subtended by the cone shaped surface 58 is less than the
angle formed by surface 60. The reason is to have better control of
the flow pattern.
As best seen in FIG. 4, air moves from fitting 14 through the
handle 62 into passage 57 by flowing through plug valve 56. A
barrier 64 divides the air passing through fitting 14 and handle 62
into two paths 66 and 68. Flow through path 66 is regulated by plug
valve 56. Valve 56 may be rotated from full open to full closed
position. The full open position will allow air to flow from the
gun through orifices 44, 46, 48 and 50 to compress the paint spray
from aperture 59 and form a flat fan shaped spray pattern. The full
closed position will result in a circular spray pattern.
Note the diamond shaped opening 70 of FIG. 5 through plug valve 56.
It receives air from the oval shaped duct 66 and allows for easy
hand manipulation of valve 56 to adjust the orifice flow with only
a small angle of rotation. Conventional O-rings around the plug
valve minimize air leaks. Alternatively, the duct 66 may be diamond
shaped and the opening 70 could be oval in cross-section.
Flow through paths 68 leads through opening 72 in a radial flange
around nozzle 58 (.Iadd.FIG. 4A).Iaddend., upstream of air chamber
52. Flow into air chamber 52 dampens flow turbulence by virtue of
its increased cross-sectional area downstream of opening 72 (as
illustrated in FIG. 4) to insure laminar flow of air through
aperture 59. Laminar flow is desirable because it maintains a more
uniform spray pattern at greater distances from aperture 59.
Note should be taken of the relatively large flow paths 66 and 68
(about 0.25 in..times.0.5 in. oval cross-section for each, see FIG.
3) and the relatively gently curving path. This is necessary
because of the desirability for high volume (about 5-60 cfm) and
relatively low pressure (less than about 10 psig). Conventional
compressor pressures are in the range 30-80 psig.
It is because of the low pressure utilized and the design of the
interior of the gun that the gun may be formed of two molded resin
halves held together by a plurality of screw combinations 74, best
illustrated in FIG. 3. With conventional air pressures the gun
would leak like a sieve because it would bulge outwardly. Note the
mating tongue-in-groove structure 75 in FIG. 3 to help minimize
leaks.
An alternative embodiment of the gun is illustrated in FIGS. 6 and
7. The difference is that the gun 10 is supplied from a convention
source of high pressure air. A combination filter and pressure
reducer valve 76 is designed to receive air at a pressure in the
range 30-80 psig and 30-60 standard cfm and delivery the same 30-60
standard cfm at less than 10 psig.
FIG. 9 shows the internal structure of filter-valve 76 and includes
a filter 78 inside a sediment bowl 80. Air will pass through the
filter and any liquid droplets or solid particles will be retained
in bowl 80. A T-handle 82 allows the operator to adjust the outlet
pressure as desired. A drain valve 84 allows liquid to be drained
from the bowl 80 periodically. Appropriate seals and connecting
thimbles and screws threads are illustrated but not specifically
described because their function appears self evident.
Another difference illustrated in FIG. 7 is the trigger mechanism
90. In FIG. 4 the flow of air is continuous, the only adjustment
possible from fitting 14 to cap 28 is the plug valve 56 controlling
flow through duct 66. In FIG. 4 the trigger assembly serves only to
open and close the needle valve to stop, start, and adjust the flow
of paint from source 27. In the embodiment of FIG. 7 the trigger
assembly 90 is designed to open and close a port 92 in the handle
by a rod 94 which works against a spring 96.
In operation in FIG. 7 an operator will squeeze the trigger 90 to
depress springs 22 and 96. Note that blocking plate 98 which blocks
port 92 is the first to move to initiate air flow to the nozzle
area through duct 68 prior to the time the trigger engages the
abutment 100 on rod 24. Thereby air will begin flowing from the
nozzle before paint flow starts. Whether or not air flows through
duct 66 when plate 98 opens port 92 is separately controlled by
plug valve 56.
Having thus described this invention in its preferred embodiment,
it will be clear that modifications may be made to the structure
without departing from the spirit of the invention.
* * * * *