Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
FILTER ASSEMB~Y
~ACKGROUND OF THE INVENTION
A continuing problem associated with the
spray application of liquid paints is the presenc~ of
foreign particulate matter in the liquid paint supply
which causes imperfections on the surfaces of an article
being spray painted $requently necessitating a refinish-
ing and repainting thereof. Such foreign particulate
matter sometimes referred to as "seeds", or "strings",
or "slugs" are formed in many instances as a result of
an agglomeration of the paint constituents during
standing or recirculation of the liquid paint necessi-
tating removal prior to discharge through the spray
nozzle. The foregoing problem is particularly pro-
nounced in recirculating-type liquid paint systems
which are in widespread commercial use for keeping
heavily-bodied pigments uniformly suspended in the
liquid paint thereby assuring uniformity in the color
and quality of the paint film applied to an article
being painted. Such recirculating paint systems
usually comprise a mixing tank equipped with suitable
agitation for maintaining the paint uniformly mixed
and a pump for transferring the liquid paint under a
desired pressure to an automatic or manual spray nozzle
in an amount in excess of that required which is re-
turned through a suitable r~turn conduit to the mixing
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tank. In spite of the provision of suitable ~ilters
in the recirculating supply line, the accumulation of
foreiyn particulate matter occurs resulting in objec-
tionable spray patterns.
The foregoing problem is also encountered
during the spray application of paints supplied from
a suction tank or cup directly connected to the spray
gun. In recognition of this problem, a variety of
filter devices have heretofore been proposed or used
in liquid paint supply systems which are adapted to be
connected at a point in close proximity to the spray
nozzle effecting a fin~l filtration just prior to entry
of the spray assembly. Prior art filter assemblies of
the types heretofoxe known are generally characterized
by their relatively large size and associated weight,
by their multiple component construction increasing the
complexity and cost of the assembly as well as diffi-
culty during cleaning and replacement of the filter
cartridges, and their relatively large volume requiring
increased time to effect a purging of the internal
volume thereof such as occasioned when changing paint
colors in a multiple-color recirculating paint supply
system. Such prior art filter assemblies because of
their size and weight have not received widespread
commercial acceptance in hand-held paint spray systems
due to the awkwardness of the resulting assembly.
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The present invention overcomes many of the
problems and disadvantages associated with prior art
filter assemblies by providiny a compact, simple, light-
weight and highly efficient inline filter assembly
which is versatile in use and can be installed at any
one of a variety of locations in a liquid paint supply
system. The compact and simple construction of the
filt~r assembly enables attachment directly to a hand-
held spray gun without materially increasing the weight
of the assembly as well as to automatic spray equip-
ment. The simplicity and efficiency of the filter
assembly facilitates periodic cleaning of the filter-
ing element thereof and provides for a 19w cost simple
and efficient assembly.
SUMMARY OF THE INVENTION
The benefits and advantages of the present
invention are achieved by an inline filter assembly
which comprises an integral tubular body member formed
with a through-bore having an annular tapered shoulder
intermediate of the upstream and downstream ends there-
of. The downs~ream end of the body member is formed
with an internal thread extending inwardly of the bore
toward the tapered shoulder for ~hreadably receiving
a male connection formed with a conically tapered seat
adjacent to the end thereof. A removable filter element
is disposed within the body member and comprises an
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annular ferrule formed with a first annular conic 1 seat
adapted to be disposed in seated sealing relationship on
the tapered shoulder within the body member and a sec-
ond annular conical seat adapted to be disposed in seated
sealing relationship on the conically tapered seat of
the male connection to which the body member is attached.
A thimble-shaped filter screen of an integral construc-
tion is affixed to the ferrule adjacent to the first
conical seat and projects axially within the bore
toward the upstream end thereo for receiving and fil-
tering a supply of liquid paint entering the upstream
end of the body member. The upstream end portion of
the filter assembly is provided with suita~le connect-
ing means such as an external thread for removably
connecting the filter assembly to a paint supply sys-
temO
Additional benefits and advantages of the
pxesent invention will become apparent upon a reading
of the Description of the Preferred Embodiments taken
in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
Figure l is a side elevational view, partly
schematic, of a typical air atomizing type spray gun
incorporating a filter assembly of the present inven-
tion connected through a quick-disconnect connection
to a pressurized liquid paint supply system;
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Figure 2 is an enlarged transverse sectional
view o the filter assembly connected to the inlet of
the spray gun as shown in Figure l;
Figure 3 is a side elevational view of the
removable filter element of the filtex assembly shown
in Figure 2;
Figure 4 is an end ~iew of the filter element
as shown in Figure 3; and
Figure 5 is a side elevational view of the
tubular body member of the filter assembly.
DESCRIPTION OF THE PREFERRED EM~ODIMENTS
Referring now in detail to the drawings, and
as may be best seen in Figure 1, a spray gun 10 of the
conventional air atomization type is shown including
a hand grip 12 having the butt end thereof connected
to an air hose 14 for supplying pressurized atomizing
air to the spray nozzle. The spray gun is further
provided with a pivotally mounted trigger 16 for con-
trolling the discharge of an air atomized spray of
paint from a mixing nozzle 18 at the forward end there-
of. The internal structural arrangements of the spray
gun 10 can be of any of the types well-known and com-
mercially available including airless type spray equip-
ment as well as manual and automatic spray equipment.
In the specific arrangement as illus~rated
in Figure 1, a supply of pressurized liquid paint
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enters the gun through a threaded coupling 20 which
in turn is secured to the filter assembly 22 of the
present invention which in turn is connected to a
coupling 24 having a quick-disconnect stem secured
thereto and removably engaged by a quick~disconnect
fitting 26 connected to a flexible paint supply tube
28. This arrangement is typical of a recirculating
paint flow control system which advantageously can
further incorporate a flow control device of the gen-
iO eral type as described in U.S. Patent No. 4,106,699.
While only one filter assembly 22 is employed in the
arrangement of ~igure 1, a second filter assembly can
advantageously be employed in the paint supply line
located at the inlet side of the quick-disconnect
coupling 26 to provide an initial fil~ering action
followed by a final filtering action by the assembly
22. This latter arrangement is particularly desirable
in a multiple color paint supply system whereby the
spray gun lO is disconnected from one color paint supply
source and connected to a second pressurized paint supply
source having a different color paint. Under such cir-
cumstances, it will be appreciated that the internal
volume of the inline filter assembly 22 is important
in minimizing purging of the prior paint color thereby
saving time ~nd also reducing wastage of paint prior
to resumption of the painting operation.
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It is also contemplated that in lieu of a
remote supply of pressurized liqui~ paint, the ~ilter
assembly 22 can be interposed in the position as shown
between a conventional suction-type paint cup directly
connected to the spray gun and portable therewith as
in the case of paint applications involving smaller
areas such in automobile body repair centers.
Referring now to Figures 2~5 of the drawing,
the filter assembly 22 comprises an integral tubular
body member 30 formed with a threaded counter-bore 32
in the downstream section thereof disposed in communi-
cation with a smooth bore 34 in the upstream section
thereof and defining at their intersection an annular
tapered shoulder 36 against which a filter element 38
is adapted to be removably seated and in axial align-
ment relative to the bore 34. The downstream end of
the body member 30 is preferably provided with flats
40 disposed in a hexagonal arrangement as shown in
Figure 5 for engagement by a wrench. The upstream
section of the body member 30 is preferably provided
with an external threaded section 42 for attachment of
the filter assembly to the paint supply conduit such as
the quick-disconnect coupling 24 as shown in Figure 1.
The filter element 38 as best seen in Figures
2-4 comprises a tubular annular ferrule 44 formed with
a first annular conical seat 46 and a second annular
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conical seat 48. The first conical seat 46 i~ prefer-
ably oriented at an angle of about 30 degrees from a
plane disposed perpendicular to the axis of the filter
element whereas the second conical seat 48 is prefer-
ably disposed at an angle of about 45 degrees from a
plane perpendicular to the axis of the filter element
and consistent with conventional taper~ on tube fittings
in accordance with national standards. The ferrule 44
is provided with an axially extending through-bore 50
and a tubular projection 52 extending axially of the
first conical seat 46. An integral thimble-shaped
filter screen 54 is disposed with the downstream end
thereof in overlying supported relationship around the
tubular projection 52 and is suitably affixed thereto
such as by bra~ing or welding. The filter screen 54
in accordance with the arrangement illustrated in Fig-
ures 2 and 3 comprises a circular cylindrical section
integrally connected to a substantially hemispherical
end section which is disposed in the path of the in-
coming liquid paint providing for a self-cleaning action
with the particulate matter moving axially along the
annular space indicated at 55 in Figure 2 toward the
ferrule of the filter element. The periphery of the
cylindxical section of the filter screen is preferably
spaced inwardly of the surface of the smooth bore 34
a distance of about 0.050 inch providing a volume for
collection of the foreign particulate matter in the
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paint.
The body member 30, the ferrule 44 and the
filter screen 54 are preferably composed of a corrosion
resistant metal such as stainlese steel, for example,
and the filter screen itself may be of about 100 to
about 160 mesh size depending on the filtering charac-
teristics desired.
In ~he assembled condition as illustrated in
Figure 2, the first conical seat 46 is disposed in
seated relationship against the tapered shoulder 36 of
the body member which effects a centering of the filter
element and a sealing of the ferrule to the body member
avoiding any paint bypass. The clamped relationship of
the filter element within the body member is achieved
by the coaction of a threaded male member 56 such as
on the coupling 20 formed with a conically tapered seat
58 at the end thereof which is adapted to seatably en-
gage the second conical seat of the ferrule retaining
the filter element in clamped relationship therebetween.
The simplicity and compact nature ~f the
filter assembly as hereinabo~e described and as illus-
trated in the drawing, provides for wide latitude and
versatility in the installation thereof at one or more
locations in a liquid paint supply system. Additionally,
~5 a cleaning of the filter screen of the filter a sembly
can readily be achieved by simply disconnecting the
tubular body member from ~he adjacent coupling enabling
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a removal of the filter element and a cleaning or re-
placement thereof as may be desired or required.
Operation down time is thereby minimized.
While it will be apparent that the preferred
embodiments of the invention disclosed are well calcu-
lated to fulfill the objects above stated, it will be
appreciated that the inven~ion is susceptible to modi-
fication, variation and change without departing from
the proper scope or fair meaning of the subjoined claims.
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