Note: Descriptions are shown in the official language in which they were submitted.
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DROP-IN FILTER FOR SPRAY GUN RESERVOIR
Field of the Invention
This invention concerns improvements in or relating to filters for liquid
supply
assemblies. The invention has particular, but not exclusive application to
liquid
supply assemblies for liquid spraying apparatus such as spray guns, especially
hand-held spray guns provided with a liquid supply assembly comprising a
reservoir for the liquid to be sprayed mounted on the spray gun.
Background of the Invention
Spray guns are widely used to apply a liquid to a substrate in a variety of
industries. In the known spray guns, the liquid is contained in a reservoir
attached
to the spray gun from where it is fed to a spray nozzle. On emerging from the
spray nozzle, the liquid is atomised and forms a spray with compressed air
supplied to the nozzle. The liquid may be gravity fed or suction fed or, more
recently, pressure fed by an air bleed from the compressed air line to the
reservoir
or even from the spray gun itself.
A common application of spray guns is in vehicle body repair shops when re-
spraying a vehicle that has been repaired following an accident. A typical
paint
finish may require application of a primer, base coat, top coat and a clear
lacquer.
The presence of contaminants such as solid particles in the liquid to be
sprayed
can spoil the paint finish and extensive re-working is required to achieve an
acceptable paint finish. In some instances, the solid particles may cause
blockage
of the spray gun itself requiring stripping down and cleaning of the spray gun
to
remove the blockage. In addition, the blockage may have an adverse effect on
the
spray and render the resulting paint finish unacceptable so that extensive re-
working is again required to produce an acceptable paint finish. Re-working of
the paint finish and, where required, unblocking of the spray gun, adds to
costs
both in terms of materials and time.
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It is already known to provide a filter in the reservoir to remove
contaminants
as the liquid is withdrawn from the reservoir during operation of the spray
gun.
Typically, the reservoir has an outlet connected to an inlet on the spray gun
and
the filter is positioned across or within the outlet. The outlet is usually of
comparatively small size compatible with the connection to the spray gun. The
presence of solid particles in the liquid added to the reservoir can result in
blockage of the filter so that flow of the liquid to the spray gun is
restricted or,
in extreme cases, prevented altogether.
A reduction in the flow of the liquid to the spray gun may have an adverse
effect on the spray and the resulting paint finish may be unacceptable so that
re-
working is again required to obtain an acceptable paint finish. Moreover,
opening of the reservoir is required to remove and replace the blocked filter
with a new filter. This is time consuming and may require decanting of liquid
remaining in the reservoir which is then returned to the reservoir when the
new
filter is in place. As a result, there is increased risk of spillage and
possible
introduction of contaminants into the liquid. Furthermore, some liquids
require
activation prior to spraying and have a relatively short life after
activation.
Delays caused by blockage of the filter may result in such liquids being
unusable thereby adding further to costs.
It is also known to filter the liquid to remove solid particles prior to or
when
adding the liquid to the reservoir by employing a filter externally of the
reservoir. This avoids the need to provide a filter within the reservoir but
is
usually time consuming due to the capacity of the filter being less than the
rate
at which the liquid can be freely poured into the reservoir. In addition,
there is
an increased risk of spillage if the addition of the liquid exceeds the
capacity of
the filter causing the liquid to overflow. Also, dust or other airborne
contaminants may be entrained in the filtered liquid with the resulting
potential
problems outlined above.
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AMENDED SHEET
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WO 98/32539 discloses a reservoir for a spray gun comprising an outer
container and an inner
liner that is a close fit in the outer container. The liner is removable
allowing a new, clean liner to
be inserted when changing the liquid to be sprayed which reduces the amount of
cleaning
required. In one arrangement (Figure 12), the reservoir has an outlet
connectable to the gun at
one end and a lid at the other end that can be removed to add paint to the
reservoir while attached
to the gun. In this arrangement, and all the liquid dispensed by the gun
passes through a mesh
filter provided inside the liner, and the filter has a size and shape similar
to the liner so there is no
need for the liquid to be filtered when it is being poured into the reservoir.
WO 02/085533 discloses a reservoir for a spray gun having an inlet opening
with a removable
closure cap that is accessible when the reservoir is attached to the spray gun
to allow liquid to be
added to the reservoir without detaching the reservoir from the spray gun. In
one arrangement, a
removable "drop-in" sock filter can be used in conjunction with the inlet
opening to filter liquid
added to the reservoir. In this arrangement, the filter is not intended to
remain in situ within the
reservoir.
Summary of Invention
The present invention is intended to provide an improved filter for liquid
supply assemblies used to
supply spray guns with resulting benefits and advantages for the user.
According to an aspect of the present invention, there is provided a liquid
supply assembly for use
with a spraying apparatus, the assembly comprising a container for containing
liquid, the container
comprising a plastic material and having a lid, a collapsible side wall and a
base on which the side
wall can stand unsupported in an upright position and said container being
capable of being
mounted on a spraying apparatus for supply of liquid to the apparatus through
an opening in the
lid, said lid also having a filler opening, separate from the opening for
connection to the spraying
apparatus, for adding liquid to the container, and a filter for filtering
liquid added to the container
through the filler opening, the filter comprising an elongate tubular body
closed at one end and
open at the other end, the open end being provided with a support collar that
is integral with the
filter body, fits in the filler opening and locates said open end so that the
filter body extends away
from the opening within the container when liquid is added to the container
through the filler
opening wherein: the tubular body of the filter is sufficiently rigid to
maintain an elongate tubular
shape and has a surface area and volume when within the container to permit,
in use, filling of the
container with liquid that is filtered on being added to the container to
produce a supply of filtered
liquid within the container for supply to the spraying apparatus when the
container is connected to
the spraying apparatus; the support collar is connected to a cage that
surrounds the tubular body
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of the filter; and the filter and cage are sufficiently flexible to allow them
to collapse as the container
collapses.
At least one embodiment of the present invention provides a filter for a
liquid supply assembly that
allows liquid to be added to a reservoir in a simple manner so that
contaminants in the liquid can
be removed at the time of adding the liquid to the reservoir.
Additionally, at least one embodiment of the present invention provides a high
flow filter for a liquid
supply assembly that permits rapid filling of a reservoir with filtered liquid
for supply to a spray gun.
Furthermore, at least one embodiment of the present invention provides a
filter for a liquid supply
assembly that can be left in place when a reservoir containing the filter is
attached to a spray gun.
Moreover, at least one embodiment of the present invention provides a filter
for a liquid supply
assembly that permits a reservoir containing the filter to collapse as liquid
is withdrawn from the
reservoir.
Other benefits and advantages of some embodiments of the invention are
referred to later herein.
As used herein, the term "liquid" refers to all forms of flowable materials
that can be applied to a
surface using a spray gun (whether or not they are intended to colour the
surface) including
(without limitation) paints, primers, base coats, lacquers, varnishes and
similar paint-like materials
as well as other fluent materials which may be applied in atomised or non-
atomised form
depending on the properties and/or the intended application of the material
and the term "liquid" is
to be construed accordingly.
In some embodiments, the tubular body of the filter extends into the reservoir
and can be arranged
so that the surface area of the filter within the reservoir is optimised
compared to the volume of the
filter. As a result, the filter can have a high flow capacity that permits
rapid filling of the reservoir
with reduced risk of spillage. In this way, liquid can be filtered as it is
poured into the reservoir to
produce a supply of filtered liquid within the reservoir for supply to the
spray gun when the reservoir
is connected to the spray gun. Consequently, the filter does not interfere
with flow of filtered liquid
supplied to the spray gun and the risk of the spray gun being blocked or the
surface finish being
contaminated with solid particles in the liquid is reduced if not eliminated.
Preferably, in some embodiments, the surface area to volume ratio of the
tubular body is such that
the liquid can be filtered at a rate compatible with the rate of addition of
the liquid to provide rapid
filling of the reservoir without spillage of the liquid. The
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surface area to volume ratio may vary depending on the properties of the
liquid,
for example viscosity, and the size of particles to be removed.
The tubular body of the filter may be comparatively rigid so as to maintain
its
shape. For example, the body of the filter may comprise a wire mesh. More
preferably, however, the tubular body is flexible so that the filter can
change
shape. For example, the body of the filter may comprise a mesh of a plastics
material such as polypropylene, polyester, polyamide (nylon) or any other
suitable material. In this way, the filter may be supplied in a compact
configuration to reduce space for storage and transportation- Furthermore,
where the reservoir is collapsible as liquid is withdrawn in use, the filter
may
be left in place within the reservoir and conform to the collapsed condition
of
the reservoir. The mesh can be woven, non-woven or knitted depending on the
material, application and requirements such as mesh size and/or uniformity.
The mesh may be formed by any suitable method, for example a plastics mesh
may be formed by moulding or extrusion.
The filter may have an axial length chosen to provide a suitable flow capacity
for the liquid to be filtered. For example, the filter may have an axial
length
substantially the same as the depth of the reservoir in which it is received.
In
this way, the available surface area of the filter within the reservoir can be
maximised for a given size of filler opening. Moreover, if the reservoir is
connected to the spray gun with the filter left in place within the reservoir,
as
the level of liquid falls in the reservoir, liquid contained in the filter can
pass
through the mesh body at the surface of the liquid. As a result, the flow of
liquid to the spray gun is not reduced or interrupted as the liquid passes
through
the mesh body.
The support collar may be sized to fit the filler opening and in some
embodiments,
preferably has an external lip at the outer end to locate and retain the
collar in the
opening. The lip may seat around the marginal edge of the filler opening at
the outer
end of the wall bounding the filler opening. Alternatively, the filler opening
may have
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a counterbore at the outer end of the wall in which the lip is received to
locate against an
internal shoulder within the filler opening. In this way, the collar is
prevented from passing
completely through the filler opening.
The support collar may be made of plastics, such as polypropylene, polyamide
(nylon) or
polyethylene and, in some embodiments, is preferably integral with the mesh
body of the
filter. For example, the support collar may be moulded onto the outer end of
the mesh body.
In this way, the support collar locates the mesh body of the filter within the
reservoir and
conforms the open end to the shape of the filler opening. For example, the
support collar
may be of circular, oval, square or other shape to match the shape of the
filler opening.
The filter may be provided with means to assist in maintaining the tubular
shape of the mesh
body at least when liquid is added to the reservoir. In one arrangement, the
filter may be
provided with support hoops extending around the mesh body at axially spaced
positions
between the ends to maintain the tubular shape of the mesh body. The support
hoops may
be integral with the mesh body, for example the support hoops may be moulded
with the
mesh body. Preferably, in some embodiments, the support hoops allow the filter
to conform
to the shape of the reservoir, for example if the reservoir is constructed to
collapse as liquid
is withdrawn in use. In another arrangement, the support collar may be
connected to a cage
that surrounds the mesh body within the reservoir. The cage may comprise a
plurality of
legs extending from the collar at the open end of the mesh body to a base
element at the
closed end of the mesh body. The legs are preferably uniformly spaced apart
and may be
flexible to allow the filter to conform to the shape of the reservoir, for
example if the reservoir
is constructed to collapse as liquid is withdrawn in use. Alternatively, the
cage may be
comparatively rigid to maintain the shape of the filter both when liquid is
added to the
reservoir and when liquid is withdrawn from the reservoir in use, for example
if the reservoir
does not collapse as liquid is withdrawn in use. The cage may be integral with
the mesh
body, for example, the cage may be moulded with the mesh body.
According to another aspect of the present invention, there is provided a
liquid supply
assembly for use with spraying apparatus, the liquid supply assembly
comprising A) a
container for containing a liquid, the container having a lid, a collapsible
side wall and a base
on which the side wall can stand unsupported in an upright position, said
container being
connectable in use to a spraying apparatus for supply of the liquid to an
inlet of the spraying
apparatus through an opening in the lid, said lid having a filler opening
separate from the
opening for attachment to the spraying apparatus for adding liquid to the
container, and B) a
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filter for filtering liquid added to the container through the filler opening,
the filter comprising
an elongate tubular mesh body closed at one end and open at the other end, the
open end
being provided with a support collar that fits in the filler opening so that
the filter body
extends away from the opening within the container, said support collar being
connected to
a cage that is integral with the filter body and effective to maintain the
tubular shape of the
filter when liquid is added to the container, said filter and cage being
sufficiently flexible to
allow them to collapse as the container side wall collapses.
Preferably, in some embodiments, the filler opening is provided in an end wall
of the
container or reservoir. In one arrangement, the container or reservoir
comprises an open-
topped container and a lid arranged to close the open end of the container and
forming the
end wall in which the filler opening is formed.
Advantageously, the lid is provided with an outlet connectable to the spray
gun. In one
arrangement, the outlet comprises a supply opening formed in the lid
separately from the
filler opening and leading to a tubular spout connectable to the spray gun. In
this way, the
filter may be left in position within the reservoir when the reservoir is
connected to the spray
gun.
The filler opening may be provided with a releasable closure such as a screw
cap that can
be removed when it is desired to add liquid to the reservoir and re-attached
to close the filler
opening when the reservoir is connected to the spray gun. With this
arrangement, access to
the filler opening may be provided to add liquid to the reservoir when the
reservoir is
connected to the spray gun.
Preferably, in some embodiments, the filler opening is larger than the supply
opening and
both openings are offset from the central longitudinal axis of the reservoir.
In this way,
access to the filler opening may be improved when the reservoir is connected
to the spray
gun to allow liquid to be added to the reservoir without disconnecting the
reservoir from the
spray gun.
In another arrangement, the filler opening is located centrally of the lid and
the outlet is
provided by a separate connector releasably secured to the lid around the
filler opening and
having a tubular spout connectable to the spray gun. In this way, the
reservoir can be
detached from the connector to provide access to the filler opening when it is
desired to add
liquid to the reservoir. With this
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arrangement, the filter is removed after adding the liquid and before the
reservoir
is re-attached to the connector.
The lid and container may be permanently secured together around the marginal
edge of the open of the container. For example the lid and container may be
bonded or welded in fluid tight manner to each other. Alternatively, the lid
and
container may be releasably secured together in fluid tight manner. For
example,
the lid may be clamped to the container.
In one arrangement, the container is collapsible as liquid is withdrawn from
the
reservoir in use. In this arrangement, the container may have a flexible
sidewall
and a comparatively rigid base such that the container can be stood upright
unsupported on the base and the sidewall is foldable to move the base towards
the
lid as liquid is withdrawn from the reservoir. The lid is comparatively rigid
and
may have a dependent skirt that is located within and secured around the inner
marginal edge of the open end of the container so that the container is
supported
by the lid. As a result, when filled with liquid and attached to the spray
gun, the
stability of the reservoir is improved assisting handling of the spray gun,
especially as liquid is withdrawn causing the reservoir to collapse. The lid
may be
provided with an extension sleeve or cage surrounding the container to provide
additional support for the container
In another arrangement, the container is received in an outer container to
which
the reservoir is secured by a collar releasably attached to the outer
container over
the lid. In this arrangement, the reservoir container acts as a liner for the
outer
container and, after use, the reservoir can be thrown away and the outer
container
and collar assembled with another reservoir.
Preferably, in some embodiments, the reservoir is adapted for releasable
connection
to the spray gun. For example, the reservoir and spray gun may be provided
with co-
operating bayonet type formations. In this way, the reservoir can be connected
to and
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released from the spray gun in a simple manner. Alternatively, the reservoir
and
spray gun may be provided with complementary screw threads.
The spray gun inlet may comprise a socket to receive the spout for connecting
the
reservoir outlet to the inlet. The spray gun and reservoir may be provided
with
the co-operating bayonet type formations or with complementary screw threads
for releasably securing the reservoir to the spray gun. In one arrangement,
the
spout and socket are provided with bayonet formations engageable within the
socket. For example bayonet lugs on the spout received in bayonet grooves in
the
socket. In another arrangement, spray gun and reservoir are provided with
bayonet formations engageable externally of the socket. For example, the
socket
may have an external flange co-operable with a pair of hook members arranged
on
opposite sides of the spout. The socket may be an integral part of the spray
gun
or it may be detachable. For example, the socket may be formed by an adaptor
permanently or releasably secured to the spray gun.
The reservoir may be supplied empty with the filter in place ready for the
user to
fill with liquid. Alternatively, the filter may be supplied separately for the
user to
insert in the filler opening before adding liquid. Where the reservoir is
collapsible, it may be collapsed to a compact form for storage and
transportation
and, after use may be discarded in the collapsed condition. The filter is
preferably also collapsible so'that it can be supplied in place with the
reservoir
collapsed and, after use, can be discarded with the reservoir.
Alternatively, the reservoir may be supplied pre-filled with liquid and the
spout
sealed until it is desired to attach the reservoir to the spray gun. For
example, the
spout may be provided with' a removable closure or a rupturable membrane.
Where provided, the membrane may be ruptured prior to or when the spout is
attached to the spray gun. In this arrangement, the reservoir may be provided
with the filter in place so that the user does not have to provide a filter
when
adding liquid to the reservoir. Alternatively, the filter may be supplied
separately
for the user to insert if it is desired to add liquid to the reservoir.
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Pre-filling may be employed for liquids that can be packaged and stored until
required without degrading. Thus, pre-filling may be useful for liquids that
can
be supplied ready for use (i.e. without requiring modification to match the
colour to an existing colour). For example, base coats in standard colours of
a
specified shade and/or primers or lacquers that can be supplied in a non-
activated form and activated (if necessary) by suitable means such as by
exposure to a source of energy, e.g. ultraviolet radiation, visible light or
electrical energy at the time of use.
The liquid supply apparatus may be used with a spray gun to provide spraying
apparatus- The spray gun may be of the gravity feed, suction feed or pressure
feed type.
Brief Description of the Drawings
Embodiments of the invention will now be described in more detail, by way of
example only, with reference to the accompanying drawings in which;-
Figure 1 is a perspective view of a spray gun for use with a liquid supply
assembly according to an embodiment of the present invention;
Figure 2 is an end view of the spray gun adaptor shown in Figure 1;
Figure 3 is a perspective view of a liquid supply assembly for use with
the spray gun of Figures 1 and 2 and incorporating a filter according to a
first embodiment of the present invention;
Figure 4 is a perspective view of the filter shown in Figure 3;
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Figure 5 is an exploded perspective view of the reservoir shown in Figure
3;
Figure 6 is a perspective view of a liquid supply assembly for use with the
spray gun of Figures 1 and 2 and incorporating a filter according to a
second embodiment of the present invention; and
Figure 7 is a perspective view of the filter shown in Figure 6.
Detailed Description of the Exemplary Embodiments
Referring first to Figures 1 to 5 of the drawings, a hand held gravity feed
spray
gun 1 (Figure 1) has an inlet adaptor 2 (Figures 1 and 2) for releasably -
connecting
a liquid supply assembly .3 (Figures 3 to 5).
The gun 1 (Figure 1) comprises a body 4, a handle 5 which extends downwards
from the rear end of the body, and -a spray nozzle 6 at the front end of the
body.
The gun 1 is manually-operated by a trigger 7 which is pivotally-mounted on
the
sides of the gun 1.
The inlet adaptor 2 (Figures 1 and 2) is located on the top of the body 4 and
communicates with an internal passageway (not visible) which extends through
the body 4 to the nozzle 6.
In this embodiment, the inlet adaptor 2 is detachable, for example a screw fit
in
the body 4. In this way, the spray gun 1 can be converted for use with
different
types of liquid supply assemblies by selection and fitment of the appropriate
adaptor 2. Also, a damaged adaptor 2 may be replaced.
In other embodiments (not shown), the inlet adaptor 2 may be an integral part
of
the body 4 of the spray gun 1. For example, the inlet adaptor 2 may be formed
with the body 4 of the spray gun 1 or it may be formed separately and
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permanently secured to the body 4 of the spray gun 1. Alternatively, the
adaptor
2 may be omitted and the liquid supply assembly mounted directly on the body 4
of the spray gun 1.
In use, the gun 1 is connected via a connector 8 at the lower end of the
handle 5 to
a source of compressed air (not shown) so that, when the user pulls on the
trigger
7, compressed air is delivered through the gun to the nozzle 6. As a result,
liquid,
for example paint, delivered under gravity from the liquid supply assembly 3
to
the nozzle 6 is atomised on leaving the nozzle 6 and forms a spray with the
compressed air emerging from the nozzle 6.
Referring now to Figures 3 to 5, the liquid supply assembly 3 depicted
comprises
a reservoir 9 for the liquid (not shown) to be sprayed and a filter 10 for
removing
solid particles when the liquid is added to the reservoir 9.
The reservoir 9 comprises a container 11 and a lid 12 (Figure 5). The
container 11
is of generally cylindrical shape having an open end 11A and a closed end 11B
connected by a flexible sidewall 11C. In this embodiment, the container 11 is
transparent and is thermo-formed from a single piece of plastics material,
preferably polyethylene or polypropylene. The container 11 can be of any
suitable size but for use with hand held spray guns, typically has a capacity
of
250, 500 or 800 ml for ease of handling and maneuverability of the spray gun
to
which the reservoir 9 is attached. The sidewall 11C may be provided with
markings (not shown) to indicate the volume of liquid in the reservoir 9.
The lid 12 is of generally annular shape and in this embodiment is also made
of
transparent plastics material, preferably polyethylene or polypropylene, by
injection moulding or other suitable process. The lid 12 has a dependent skirt
12A inset from the marginal edge 12B. The skirt 12A is received inside the
open
end 11A of the container 11 and locates against an annular step 11D in
sidewall
11C. The marginal edge 12B of the lid 12 seats on an external flange 11E at
the
open end of the container 11. The lid 12 is permanently secured to the
container
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11 by adhesive or welding between the skirt 12A and sidewall 11C and between
the marginal edge 12B and the flange 11 E.
The lid 12 is comparatively rigid compared to the sidewall 11C of the
container
and maintains the annular shape of the open end 11A of the container 11. The
closed end 11B of the container 11 is also comparatively rigid compared to the
sidewall 11C and provides a flat base on which the reservoir 9 can stand,
unsupported, in an upright condition with sidewall 11C extended (Figure 3).
The sidewall 11C is flexible and can be made to collapse as liquid is
withdrawn
from the reservoir 9 for supply to the spray gun 1. As the sidewall 11 C
collapses,
the comparatively rigid base 11B retains its form but moves towards the lid
12.
The sidewall 11C collapses in a similar fashion to a plastic bag without being
ruptured (e.g. by splitting, tearing or cracking).
The lid 12 has an upper surface 12C of convex shape and is formed with an
inlet
or filler opening 12D and an outlet or supply opening 12E. The filler opening
12D has a diameter of approximately half the diameter of the lid 12 and.is
bounded on the upper surface 12C by an annular spigot 14 having an external
screw thread 14A. The filler opening 12D is closed by a detachable screw cap
15
having a skirt 15A with an internal screw thread complementary to the external
screw thread 14A of spigot 14.
The supply opening 12E has a diameter of approximately one sixth the diameter
of the lid 12 and'is bounded on the upper surface 12C by a cylindrical spout
16.
The spout 16 is sized to -be a push-fit in a counterbore 17 (Figure 2) at the
outer
free end of the adaptor 2.
In this embodiment, the spout 16 has external annular ribs 16A that provide a
fluid-tight seal within the counterbore 17. It will be understood, however,
that
any suitable sealing means may be provided such as one or more O-rings in the
counterbore 17 and/or on the spout 16.
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The filler opening 12D is much larger than the supply opening 12E and is made
as
large as possible to facilitate addition of liquid to the reservoir 9 from the
same
end as the supply opening 12E. In this way, liquid can be added to the
reservoir
through the filler opening 12D with the reservoir in an upright position
either free
standing on the base or with the supply opening 12E attached to the spray gun
1.
In this embodiment, the ratio of the cross-sectional area of the filler
opening 12D
to that of the supply opening 12E is approximately 9:1 but it will be
understood
that different sizes of the openings 12D,12E may be employed.
The openings 12D,12E in the lid 12 are offset from the central longitudinal
axis
of the reservoir 9 and- extend at an angle to the longitudinal axis. In this
way,
access to the filler opening 12D is improved for adding liquid to the
reservoir 9
when the reservoir 9 is attached to the spray gun 1.
In this embodiment, opening 12D extends at an angle of approximately 17 and
the opening 12E extends at an angle of approximately 13 to the longitudinal
axis
of the reservoir 9, i.e. at an angle of approximately 30 to each other. It
will be
understood that one or both openings 12D, 12E may be extend parallel to the
longitudinal axis or at any angle to the longitudinal axis as desired.
The lid 12 is also provided with a pair of hook members 18,18' arranged on
opposite sides of and spaced from the spout 16. The hook members 18,18', spout
16 and spigot 14 are aligned on a diameter of the lid 12..
Each hook member 18,18' is similar and has an enlarged head 18A,18A'
respectively with a chamfer. face 18B,18B' terminating at an undercut rib
18C,18C'.
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The inlet adaptor 2 on the spray gun has an external flange 2A at the outer
end for
co-operating with the hook members 18,18' to secure releasably the reservoir
to
the spray gun with the spout 16 received in the counterbore 17.
As best shown in Figure 2, the flange 2A comprises four arcuate recesses
19,20,21,22 uniformly spaced in a circumferential direction around the outer
periphery such that the recesses 19,21 are opposite each other and the
recesses
20,22 are opposite each other.
Each recess 19,20,21,22 leads in a clockwise direction (as viewed in Figure 2)
via
a cam lobe 19A,20A,21A,22A to a flat 23,24,25,26 that terminates in an
abutment
23A,24A,25A,26A.
In use, to secure the reservoir 9 to the inlet adaptor 2, the hook members
18,18'
are aligned with a pair of opposed recesses 19,21 or 20,22 in the flange 2A.
The
spout 16 is then pushed into the counterbore 17 so that the enlarged heads
18A,18A' at the distal ends of the hook members 18,18' pass through the
aligned
recesses 19,21 or 20,22.
The reservoir 9 is then rotated relative to the inlet adaptor 2 to cause the
hook
members 18,18' to ride over the cam lobes 19A,21A or 20A,22A and locate
locking ribs 18C,18C' of the heads 18A,18A' behind the flats 23,25 or 24,26.
In
this way, the reservoir 9 is secured to the inlet adaptor 2 and axial
separation of
the reservoir 9 from the inlet adaptor 2 is resisted. The reservoir 9 can be
detached from the inlet adaptor 2 by reversing the above operation.
The offset arrangement of the spout 16 from the central longitudinal axis of
the
reservoir 9 coupled with the push-twist fastening action to secure the
reservoir 9
may result in the reservoir overhanging the body 4 of the spray gun 1 to one
side.
By providing two pairs of opposed recesses 19,21 and 20,22, the reservoir 9
can
be attached using the pair of recesses 19,21 or 20,22 which reduces or
eliminates
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overhang of the reservoir 9. In this way, balance of the assembled gun 1 and
reservoir 9 is improved for ease of handling and maneuverability.
The filter 10 is inserted in the filler opening 12D and extends to the bottom
of the
reservoir 9 to remove any solid particles from liquid added to the reservoir 9
through the filler opening 12D with the cap 15 removed.
As best shown in Figure 4, the filter 10 comprises a tubular mesh body 10A
closed at one end and open at the other end. In this embodiment, the mesh body
10A is made of plastics such as polypropylene, polyester or polyamide (nylon)
having a mesh size to remove particles of 40 microns or larger, potentially up
to
1000 microns. It will be understood that the mesh body l0A may be made of
other materials and may have any desired mesh size to suit any given
application.
The filter 10 is provided with a comparatively rigid annular collar 27 at the
open
end of the mesh body 10A. The collar 27 is made of plastics, for example
polyamide (nylon), polypropylene or polyethylene, and is integral with the
mesh
body 10A, for example the collar 27 may be moulded onto the mesh body I OA.
The collar 27 is sized to be a push-fit in the spigot 14 and has an external
annular
lip 27A at the outer end that locates on the outer end of the spigot 14 to
position
the filter 10 within the reservoir 9 and provide a seal between the screw cap
15
and the filler opening 12D. The mesh body 10A of the filter 10 is generally
cylindrical having a maximum diameter similar to the diameter of the filler
opening 12D so that the filter can be easily inserted in the filler opening
12D.
In this embodiment, the axial length of the mesh body 1OA is such that the
closed
end is located adjacent to the base of the reservoir 9 when the collar 27 is
seated
in the spigot 14. In this way, surface area to volume ratio of the tubular
mesh
body 10A can be optimised for the mesh size of the filter and the properties
of the
liquid to be added.
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As a result, the filter 10 has a high flow capability that allows liquid to be
poured
into the reservoir 9 through the filler opening 12D without overflowing or
spilling. This permits rapid filling of the reservoir 9 with liquid that has
been
filtered to remove solid particles.
The mesh body 10A is flexible so as to be collapsible with the reservoir 9 as
liquid is withdrawn from the reservoir 9 in use. In this way, the filter 10
can be
left in place within the reservoir 9 after filling and the screw cap 15
attached to
close the filler opening 12D and secure the filter 10 in position.
The outlet opening 12E is separate from the filler opening 12D and the
presence
of the filter 10 in the reservoir 9 does not interfere with flow of liquid to
the spray
gun 1 through the spout 16. Also, the reservoir 9 contains filtered liquid for
supply to the spray gun *1 so that the flow of liquid is not dependent on the
filtering the liquid at the time it is withdrawn from the reservoir 9.
As the level of the liquid falls in the reservoir 9, liquid contained in the
mesh
body 10A can pass through the mesh body 10A into the reservoir 9 at the
surface
of the liquid in the reservoir 9. As a result, the supply of the liquid to the
spray
gun 1 is not affected by filtering of the volume of liquid contained in the
filter
body 10A when the reservoir 9 is filled.
In an alternative arrangement, the filter 10 may be removed after filling with
liquid and the screw cap, 15 attached to close the filler opening 12D prior to
attaching the reservoir 9 containing filtered liquid to the spray gun 1.
By leaving the filter 10 in the reservoir 9, the risk of spillage when the
filter 10 is
removed is avoided. Also, if it is desired to top-up the reservoir 9. with
more
liquid, the screw cap 15 .can be removed and the liquid poured into the
reservoir
through the filler opening 12D with the filter 10 already in place to remove
any
solid particles.
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Referring now to Figures 6 and 7, a liquid supply assembly is shown having an
alternative filter according to the invention. For convenience like reference
numerals in the series 100 are used to indicate parts corresponding to the
previous
embodiment.
As shown in Figure 7, the mesh body 110A of the filter 110 is arranged inside
a
support cage 128 integral' with the collar 127. In this embodiment, the
support
cage 128 comprises four legs 128A extending axially from the collar 127 and
joined to a base ring 128B at the closed end of the filter body 110A. The
support
cage 128 helps to maintain the tubular shape of the filter body 110A when
liquid
is added to the reservoir 109.
The surface area of the mesh body 110A is again optimised compared to the
volume of the filter 110 to provide a high flow capability for rapid filling
of the
reservoir 109 with filtered liquid.
In this embodiment. the legs 128A are comparatively rigid to provide
strengthen
and maintain the tubular shape of the mesh body 110A. With this arrangement,
after filling the reservoir 109, the filter 110 is removed before the screw
cap 115
is attached to close the filler opening 112D prior to securing the reservoir
109 to
the spray gun 1 (Figure 1). In this way, the filter 110 does not interfere
with
collapse of the reservoir, 109 as liquid is withdrawn in use. In other
respects, the
construction and operation of this embodiment is similar to the previous
embodiment and will be understood from the description already given.
In a modification (not shown), the cage 128 may be replaced by a plurality of
annular support hoops (not shown) that extend around the mesh body 110A at
axially spaced positions.. The hoops provide strength to maintain the tubular
shape of the mesh body 110A when liquid is added to the reservoir 109 but
allow
the filter 110 to collapse with the reservoir 109 as liquid is withdrawn in
use. In
this way, after filling with liquid, the reservoir 109 can be connected to the
spray
gun with the filter 110 left in place within the reservoir 109. Alternatively,
the
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cage 128 may be formed to allow the filter 110 to collapse, for example the
legs
128 could be flexible.
It will be appreciated from the foregoing description of exemplary embodiments
that by having the filler opening 12D, 112D separate from the supply opening
12E, 112E liquid can be added to the reservoir 9, 109 with the reservoir 9,
109
connected to the spray gun 1. For this, the spray gun 1 is inverted from its
normal
position of use so that the reservoir 9, 109 is arranged with the lid 12, 112
uppermost to drain any liquid remaining in the reservoir 9, 109 to the bottom
(the
reservoir 9, 109 may have to be extended from the collapsed condition
resulting
from withdrawal of liquid during spraying). The screw cap 15, 115 can then be
removed to add more liquid without risk of spillage. The cap 15, 115 can then
be
re-attached and the spray gun 1 re-inverted to its normal position of use for
continued spraying.
Alternatively, the reservoir 9, 109 may be detached from the spray gun' 1 and
stood upright on a flat surface with the lid 12, 112 uppermost prior to
removing
the screw cap 15, 115 to add more liquid (the reservoir 9, 109 may have to be
extended from the collapsed condition resulting from withdrawal of liquid
during
spraying). The cap 15, 115 can then be re-secured and the reservoir 9, 109 re-
attached to the spray gun 1 to continue spraying.
On completion of spraying, the reservoir 9, 109 may be detached from the spray
gun 1 and any paint remaining in the reservoir 9, 109 may be stored
temporarily
by closing off the supply hole 12E, 112E with any suitable means. The
reservoir
9, 109 may then be re-attached to the spray gun 1 to use the remaining liquid.
Alternatively, the reservoir 9, 109 may be discarded together with the filter
10,
110 after closing off the supply hole 12E, 112E.
It will be understood that the invention is not limited to the embodiments
above-
described.
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For example, the arrangement of the filler opening separate from the supply
opening allows the filter to be left in situ when attaching the reservoir to
the spray
gun and enables liquid to be added with the reservoir attached to the spray
gun.
The filler opening and supply opening may be provided in the lid at the same
end
of the reservoir. Alternatively, the filler opening may be provided in a
sidewall or
base wall of the container and the supply opening in the lid.
In another arrangement, the lid may be provided with a centrally located
filler
opening to receive the filter and a separate connector having an outlet spout
for
securing the reservoir to the spray gun. The connector is releasably attached
to
the lid around the filler opening and converts the lid for connection to the
spray
gun after the liquid has been added to the reservoir. With this arrangement
the
reservoir can be detached from the connector and liquid added to the reservoir
with the filter inserted in the filler opening. The filter is then removed and
the
reservoir attached to the connector for securing the reservoir to the spray
gun.
The lid and container may be permanently secured together as described.
Alternatively, the lid and container may be releasably secured together. For
example, the container may form a liner for a rigid outer container with the
lid
being releasably secured to the liner by a collar screwed onto the outer
container.
A liquid supply assembly of this type forms the subject matter of our
International
patent application published on 30 July 1998 under No.WO 98/32539.
The reservoir may be collapsible as liquid is withdrawn. In this arrangement,
the
filter may be flexible so as to be collapsible with the reservoir when the
filter is
left in place and the reservoir attached to the spray gun. Alternatively, the
filter
may be stiff compared to the reservoir so that the filter has to be removed
before
attaching the reservoir to the spray gun.
The reservoir may be supplied empty with the filter in place so that the user
only
has to remove the screw cap and add the liquid to be sprayed. Alternatively,
the
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filter may be supplied separately for insertion in the filler opening by the
end user
prior to adding liquid.
Where the reservoir is collapsible, it may supplied empty in a collapsed
condition
so as to reduce the space required for storage and transportation with the end
user
extending the reservoir before adding liquid. In this arrangement, the
reservoir
may be supplied with the filter in place in a collapsed condition or separate
for
insertion in the filler opening by the end user.
In another arrangement, the reservoir may be supplied pre-filled with liquid.
In
this arrangement, the filter may be supplied separately for insertion by the
end
user if it is desired to add liquid to the reservoir in use. Alternatively,
the
reservoir may be supplied with the filter in place so that liquid can be added
by
the end user when required.
In a further arrangement, the reservoir may be rigid. With this arrangement,
the
filter may be flexible or. stiff and may be left in place when the reservoir
is
attached to the spray gun. The reservoir may be supplied empty or pre-filled
with
liquid and with the filter secured in place or separate. With this
arrangement, an
air vent is required in, the liquid delivery system to allow liquid to be
withdrawn
from the reservoir in use, for example the reservoir may be provided with an
air
hole that can be opened when the reservoir is connected to the spray gun.
Other modifications and improvements will be apparent to those skilled in the
art.
As will now be apparent, the present invention provides a high flow, drop-in
filter
for use with a liquid supply assembly for spraying apparatus such as spray
guns to
permit rapid filling of the reservoir. In this way, the liquid is filtered on
being
added to the reservoir to provide a supply of filtered liquid for delivery to
the
spray gun.
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- Furthermore, by providing a filler opening separate from the supply opening,
the filter can be left in place when the reservoir is attached to the spray
gun so
as to be available if it is desired to top-up the reservoir with more liquid.
Additionally, by providing the filter with a-flexible mesh body, the filter
can be
employed both in reservoirs that are collapsible as liquid is withdrawn and in
reservoirs that are rigid.
It will also be appreciated that the exemplary embodiments described herein
are intended to illustrate the diverse range and application of the invention
and that, features of the embodiments may be employed separately or in
combination with any other features of the same or different embodiments.
Moreover, while the exemplary embodiments described and illustrated are
believed to represent the best means currently known to the applicant, it will
be
understood that the invention is not limited thereto and that various
modifications and improvements can be made within the scope of the claims
hereinafter.
22
AMENDED SHEET
