Note: Descriptions are shown in the official language in which they were submitted.
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LIQUID SAMPLE RESERVOIR SUITABLE FOR USE WITH A
SPRAYING APPARATUS
Technical Field
This invention relates to containers. More particularly, but not exclusively,
it relates to a container which is a liquid sample reservoir suitable for use
with apparatus for spraying a liquid. Even more particularly, but not
exclusively, it relates to a said liquid sample reservoir which is disposable.
Background
Spray guns, as used in vehicle body shops for example, are well known and
comprise a reservoir in which a liquid to be dispensed is contained, and a
spray nozzle through which the liquid is dispensed, typically under
pressure, under the control of a trigger mechanism, see for example Figure
1. The liquid may be fed from the reservoir under gravity and/or it may be
entrained in a stream of pressurised fluid, for example air and water, which
is supplied to the gun from an external source.
The spraying of colour match test cards (also known as spray out cards), or
small areas of vehicles, is often carried out prior to the painting of a whole
vehicle. Test cards, see for example Figure 3, are typically made from
cardboard, metal or plastic and can have a comparison hole, typically 7mm
in diameter, cut through them and an opacity check region. Paint to be
sprayed onto the test card is premixed from commercially available tinters,
typically mixed in small volume containers such as, for example, plastic or
paper cups, and an aliquot is loaded into the spray gun. A sufficient
number of coats of the paint, which may be either solvent based or water
based, to totally obscure the opacity check region are sprayed onto the card.
The card is then baked dry and a number of coats of a lacquer, which is
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typically solvent based, are applied over the paint. The lacquer is then
baked dry and the paint compared to the desired colour through the
comparison hole by overlaying the card onto a panel of the vehicle having
the desired colour.
Small test aliquots of paint are generally taken from large batches of mixed
pigments in order to increase the uniformity of the mixture as any error in
mixing the pigments to make the paint mixture is amplified by the use of
small weights in mixing, for example, a 5g error in mixing 50g of paint is a
10% error whereas the same weight error in mixing 500g represents only
1% error in pigment mix. Weight measurements have been found to be
more accurate than volumetric measurements for mixing purposes.
However, if a standard, large volume, paint reservoir is used on the spray
gun to spray a test piece and the paint is not a good match a large amount
of cleaning of the system is required prior to spraying another test piece
with a retinted paint mixture in order to prevent cross-contamination
between the two paint mixtures. The cleaning of the system is a time
consuming, labour intensive operation, increases the amount of solvents
used and can also expose users to noxious solvent vapours. One solution to
this problem, the use of a disposable paint reservoir liner, see for example
Figure 2, has been discussed in the PCT Publication
No: WO 98/32539 which is assigned to the Minnesota
Mining and Manufacturing Company.
The use of standard size beverage cups for mixing also reduces the
opportunities for cross-contamination between colours as the cups are
readily disposed of after use and a new cup is used for each colour. This
can lead to large variations in colour between small volume paint mixes
and large volume paint batches which are ostensibly the same colour.
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The use of small volume containers, such as for example cups, for the
mixing of paints does however have a number of problems associated with
it. The containers are typically open to their surroundings which can lead
to contamination of the paint, generally by particulates or, less likely, by
water. The particulates may block the flow path or spray nozzle of the
spray gun thereby preventing the spraying of the test card or vehicle and
necessitate a complete strip down, clean and overhaul of the spray gun.
The introduction of water into a non-water based paint mixture can lead to
the formation of a two-phase system or an emulsion that results in an
uneven flow rate due to the differing hydrodynamic properties of the paint
mixture and water.
Another problem associated with the use of small, open containers such as
cups for colour mixing purposes is that it requires the transfer of the
pigments from storage containers to the container in order to achieve the
desired shade. This can entail the use of jugs that must be thoroughly
cleaned with solvents after each use in order to prevent cross-contamination
between pigments. The solvents employed in the cleaning process are often
inflammable, noxious and/or poisonous and therefore it is desired to
minimise their usage wherever possible both for environmental and health
reasons.
Different batches of a colour made to ostensibly the same recipe, from
ostensibly the same pigments, will typically vary slightly in coloration.
Therefore it is usual practice to mix a large batch of a given colour and
make variations to the mixture of this large batch and transfer a small
amount of the batch to the spray gun reservoir for colour matching
purposes. However, varying the paint mixture in the reservoir to achieve a
colour match and to "scale up" these variations to the batch in order to
attempt to achieve a colour match in the large batch is not always
successful for the reasons discussed hereinbefore.
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Another problem of current paint mixing arrangements is that should a
customer wish to retain a small amount of the paint, for example, for
possible "touching up" of any future scratches to their vehicle, the paint
must be transferred to a sealable container for them. This again raises the
problems of contamination of the paint by particulates and also the need to
dispose of the reservoir after use.
A paint feed system is disclosed in JP 11290728 comprising a pair of
piston/cylinder units operable in tandem to provide a continuous supply of
paint to a robotic spray gun. The piston of each unit is driven by a
servomotor under the control of a controller to connect alternately the units
to the paint supply and spray gun. In this way, one unit takes up paint as
the piston is retracted and the other unit delivers paint as the piston is
advanced. This system is designed for continuous supply of paint of one
colour and is not suitable for rapid changing over between colours due to
the extensive cleaning of the units and supply lines that would be required.
It is also designed for use with a remote spray gun such as carried by a
robot arm and is neither intended nor capable of being used with a hand-
held spray gun.
Summary
It is an aim of the present invention to provide a fluid reservoir which, in
an embodiment thereof, at least partly, ameliorates at least one of the
above-mentioned problems.
It is a further desired aim of the present invention to provide a fluid
reservoir that is lightweight, of simple construction and facilitates
changeover of spraying apparatus to spray different fluids with reduced
cleaning required to avoid cross-contamination.
It is yet another desired aim of the present invention to provide a fluid
reservoir that can be charged manually with the fluid to be sprayed and
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allows the fluid to be withdrawn without requiring actuation by the user or
any other applied force when the reservoir is connected to the spraying
apparatus.
It is a still further desired aim of the present invention to provide a single
use, disposable fluid reservoir for use with hand held spraying apparatus
whereby the reservoir can be detached and thrown away after use.
It is another desired aim of the present invention to provide a fluid
reservoir for supplying a relatively small volume of fluid suitable for
spraying a small area such as when test spraying for colour matching
purposes.
Other aims and objects of the present invention will be apparent from the
description hereinafter of exemplary embodiments.
According to a first aspect of the present invention there is provided a fluid
reservoir for a spray gun, the reservoir comprising a body having a first,
substantially closed end and a second, open end, the open end being
connectable, in use, to a spray gun, and a vacuum forming element operable
to create at least a partial vacuum within the body for drawing fluid into the
reservoir via the open end when disconnected from the spray gun
characterised in that means is provided for controlling said at least partial
vacuum whereby, when the open end of the reservoir is connected to the
spray gun, fluid can be withdrawn from the reservoir via the open end for
supply to the spray gun independently of an actuation force applied to the
vacuum forming element externally of the reservoir.
By this invention, the vacuum forming element is operable to draw up a
required volume of fluid, typically paint, into the reservoir and the partial
vacuum created thereby is controlled so that the fluid can be withdrawn for
supply to a spray gun without actuating the vacuum forming element to
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expel the fluid from the reservoir. This facilitates use of the reservoir with
a hand-held spray gun of the type employed in vehicle body repair shops by
avoiding any manual actuation of the reservoir by the operator to transfer
the paint to the spray gun while spray painting.
In a first embodiment, the body may be a syringe body and the vacuum
forming element may be a plunger having a sealing member resident in the
body and a shank passing through an opening in the first end for manual
actuation of the plunger.
The sealing member frictionally engages a wall of the body to divide the
syringe body into two chambers and is slidable in the axial direction of the
body in response to actuation of the plunger to vary the relative volumes of
the two chambers. In this way, movement of the sealing member away
from the second, open end towards the first end creates a partial vacuum
(pressure differential relative to atmospheric pressure) in the body for
drawing fluid into the reservoir, in use.
The means for controlling the partial vacuum may be an aperture through
the wall of the body. The aperture will typically be proximate the first end
of the body and, in use, may allow the passage of air into/out of the body,
as the plunger is entered into/withdrawn from the body. The aperture
allows a sufficient intake/expelling of air that there is not a vacuum/build
up of pressure to such an extent that the plunger has its translation
restricted by a pressure differential. This is important, as there will
generally be little clearance between the opening in the first end and the
plunger so as to limit the opportunity for the ingress of particles into the
reservoir.
In use, the plunger may be drawn to a first position where the sealing
member is between the second, open end of the body and the aperture to
create the at least partial vacuum to draw fluid into the reservoir and retain
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the fluid in the reservoir. The plunger may then be drawn to a second
position, after attachment to the spray gun, where the sealing member is
between the aperture and the first, substantially closed end to release the at
least partial vacuum. This allows air to enter the syringe as fluid is
withdrawn from the reservoir by the spray gun, whilst limiting the
opportunities for contamination of the paint. Thus, paint can be drawn
from the reservoir via the open end by the spray gun without an actuation
force being applied to the plunger externally of the reservoir to move the
sealing member towards the second, open end. As a result, the operator
only has to actuate the spray gun trigger in the normal manner and no
additional actuation of the reservoir is required to transfer the paint from
the reservoir to the spray gun. This gives the operator freedom to position
the spray gun to direct the spray onto the surface to be coated without any
adverse effect on the paint supply to the spray gun.
Alternatively, or additionally, the means for controlling the at least partial
vacuum may be a passageway passing through the plunger. The passageway
may extend from the sealing member within the body to a position
externally of the body. The passageway may be releasably sealed
externally of the body by a cover. The cover may frictionally engage the
plunger. Alternatively, the cover may be pivotally mounted with respect to
the plunger. In this way, the passageway may be sealed to create, in use,
the at least partial vacuum to draw fluid into the reservoir as the plunger is
withdrawn. The cover may then be released to open the passageway and
release the at least partial vacuum. This allows air to enter the syringe as
fluid is withdrawn from the reservoir by the spray gun, whilst limiting the
opportunities for contamination of the paint. Thus, paint can be drawn
from the reservoir via the open end by the spray gun without an actuation
force being applied to the plunger externally of the reservoir to move the
sealing member towards the second, open end.
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The second, open end of the body may have a mounting extending
therefrom. A closure may be provided for releasably closing the mounting.
The closure may be a cap. The mounting and the cap may have
complementary screw threads so as to be able to be screwed together, in
use. Alternatively, the closure may frictionally engage an internal wall of
the mounting, in use. These closure arrangements allow small volumes of
paint to be stored, for example, either to aid in subsequent colour matching
or to allow customers to take small amounts of paint so that they can
"touch up" small scratches or flaws in their vehicles paint work.
In another embodiment, the body may be a collapsible body. The body may
be a concertina type arrangement, for example the body may be a bellows.
The vacuum forming element may be an integral part of the body. The
body may have an open end and a closed end. The closed end may
constitute the vacuum forming element with the open end permitting fluid
to be drawn into and expelled from the body. The open end may have a
mounting, as detailed hereinbefore, to which a releasable closure, as
detailed hereinbefore, may be affixed. This is a convenient, typically
disposable, way of providing a liquid reservoir.
In use, the body may be collapsed and subsequently extended to create the
at least partial vacuum to draw fluid into the body through the open end.
The body may then be attached to a spray gun and the vacuum controlled
by collapse of the body as fluid is withdrawn from the reservoir by the
spray gun. In this way, the fluid can be withdrawn without an actuation
force being applied to the closed end (vacuum forming element) externally
of the reservoir. In a modification, the closed end may be provided with an
aperture that is normally closed but can be opened to release the at least
partial vacuum and assist collapse of the body as fluid is withdrawn from
the reservoir.
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In yet another embodiment, the body may be a pipette. The body may have
a distended portion between the first and second ends. The distended
portion may, in use, serve as a reservoir. The vacuum forming element
may be a pipette bulb. The bulb may be integrally formed with the pipette.
Alternatively, the vacuum forming element may be a pipette safety filler.
The open end may have a mounting, as detailed hereinbefore, to which a
closure, as detailed hereinbefore, may be affixed.
In use, the vacuum forming element may be actuated to create the at least
partial vacuum within the body to draw fluid into the body through the
open end. The body may then be attached to the spray gun and the at least
partial vacuum released, for example by opening an air passageway, to
allow the fluid to be withdrawn from the body without application of an
actuation force to the vacuum forming element externally of the reservoir.
An adapter may be provided for enabling any of the embodiments detailed
hereinbefore to be attached to a spray gun, in use. The adapter may be
releasably attached to the mounting and adapted, in use, to be received
releasably in a mount of the spray gun.
The reservoir may have a filter. The filter may be positioned internally or
externally of the reservoir for removing particulates when drawing fluid
into the reservoir and/or when withdrawing fluid from the reservoir. The
filter may be positioned over the open end of the reservoir. The filter may,
or may not, be removed from the reservoir prior to the attachment of a
spray gun, in use. The use of a filter acts to prevent the entrainment of
undesirable particulates into the spray gun nozzle and consequently
improves the evenness of coverage of the paint and also prevents the
blockage of the nozzle.
The reservoir may have a volume of between any one pair of the following
values: <25m1, 25m1, 30m1, 50ml, 75m1, 100ml, 150ml, 250m1 or >250ml.
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The reservoir may be a single-use, diposable reservoir in the sense that it is
intended to be thrown away when the fluid has been used and is not
intended to be cleaned and re-used with another fluid. However, fluid
contained in the reservoir may be stored by releasably sealing the reservoir
to enable the fluid to be used when required, for example when applying
multiple coats with the same fluid to allow drying in-between. The
reservoir may substantially prevent the escape of solvent vapour.
The body of the reservoir may be substantially made of plastics material
selected, for example from the group comprising polyethylene and
polypropylene. This together with the relatively low volume of the
reservoir referred to previously produces a simple, compact, lightweight
construction of reservoir that is especially suitable for use with hand held
spray guns. The plastics material may be opaque for use with light
sensitive fluids. Alternatively, the plastics material may be substantially
transparent or translucent or provided with a transparent or translucent
window for inspecting the contents of the reservoir and the body may have
a scale marking to indicate a volume of fluid within the reservoir.
According to a second aspect of the present invention there is provided a
fluid reservoir comprising fluid retention means for detachable connection
to a spray gun, and vacuum forming means for creating a partial vacuum
(pressure differential) within the fluid retention means so as to draw a fluid
into the retention means, in use, and means for releasing the partial vacuum
to allow the fluid to be withdrawn from the reservoir when connected to the
spray gun.
The fluid retention means may comprise a syringe body with the vacuum
forming means being a plunger slidable in the body to draw the fluid into
the body via an open end. The means for releasing the partial vacuum may
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be an airway for connecting the partial vacuum to atmospheric pressure
externally of the reservoir.
Preferably, the airway is arranged to release the partial vacuum without
removing the plunger from the body. For example, the airway may be
formed by an aperture in the wall of the body and the plunger can be
withdrawn to release the partial vacuum via the aperture. In this way, fluid
may be withdrawn from the body without applying an actuation force to the
plunger externally of the body to move the plunger towards the open end.
Advantageously, the syringe body and plunger form a single-use disposable
reservoir that can be thrown away after use. Alternatively, the open end of
the syringe body may be sealed releasably by a detachable closure so that
the fluid can be stored until required for use.
According to a third aspect of the present invention there is provided a
fluid reservoir for a spray gun, the reservoir comprising a body having a
first, substantially closed end and a second, open end, the open end being
connectable, in use, to a spray gun, and a vacuum forming element operable
to create at least a partial vacuum within the body for drawing fluid into the
reservoir via the open end when disconnected from the spray gun
characterised in that the vacuum forming element is manually operable to
draw fluid into the reservoir via the open end and the reservoir is adapted,
when connected to the spray gun, so that fluid can be withdrawn from the
reservoir via the open end for supply to the spray gun without operation of
the vacuum forming element.
According to a fourth aspect of the present invention there is provided a
fluid reservoir for a spray gun, the reservoir comprising a compact,
lightweight syringe of low volume having a syringe body connectable to a
spray gun via an opening at one end, a plunger reciprocal in the body for
manually drawing fluid into a fluid chamber within the body via the
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opening when disconnected from the spray gun, and an openable airway for
connecting the fluid chamber to atmosphere to allow transfer of fluid from
the fluid chamber to the spray gun, in use.
According to a fifth aspect of the present invention there is provided a
spray gun adapted to include a reservoir according to any of the first,
second, third and fourth aspects of the present invention.
The spray gun may be a gravity fed spray gun. Alternatively, it may be a
pressure feed spray gun.
According to a sixth aspect of the present invention there is provided a
method of providing a paint reservoir adaptable for use with spraying
apparatus including the steps of:
i) providing a body open at one end;
ii) providing a vacuum forming element;
iii) placing the open end in a paint;
iv) forming an at least partial vacuum (pressure differential) within the
body using the vacuum forming element;
v) drawing paint into the body by the partial vacuum;
vi) retaining the paint in the body until such time as it is required to be
used; and
vii) releasing the partial vacuum to allow the paint to be withdrawn from
the reservoir when connected to the spraying apparatus.
The method may further include withdrawing the paint from the reservoir
in use of the spraying apparatus. The method may further include the step
of providing an adapter to adapt the body for connection to the spraying
apparatus. The method may further include the step of providing the
reservoir in combination with the spraying apparatus. The method may
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further include releasably sealing the open end of the body with- the paint
inside, in use. The spraying apparatus may be a spray gun.
According to a seventh aspect of the present invention, there is provided a
method of spraying a vehicle comprising the steps of:-
a) preparing a paint mix;
b) withdrawing a portion of the paint mix into a disposable reservoir of
low volume;
c) attaching the reservoir to a spray gun;
d) spraying a test card;
e) comparing the test card with a vehicle to be spray painted;
f) repeating steps (b) to (e) as necessary with adjustments to the paint
mix and using a new disposable reservoir when preparing each test
card until a colour match is obtained between the test card and the
vehicle;
g) charging the spray gun with the paint mix; and
h) spraying the vehicle.
The spray gun may have a detachable reservoir and the method further
includes providing the detachable reservoir with a removable, disposable
liner when charging the spray gun with paint mix in step (g).
It will be understood that the term "paint" is used herein to include all
forms of paint-like coating materials that can be applied to a surface using
a spray gun, whether or not they are intended to colour the surface. The
term includes, for example, primers, base coats, lacquers and similar
materials.
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According to another aspect, there is provided a fluid reservoir for a
spray gun, the reservoir comprising a body having a first, closed end and a
second,
open end, the open end being connectable, in use, to the spray gun, and a
vacuum
forming element operable to create at least a partial vacuum within the body
for
drawing fluid into the reservoir via the open end when disconnected from the
spray
gun, wherein means is provided for controlling said at least partial vacuum
whereby,
when the open end of the reservoir is connected to the spray gun, fluid is
withdrawn
from the reservoir via the open end for supply to the spray gun independently
of an
actuation force applied to the vacuum forming element externally of the
reservoir.
According to another aspect, there is provided a method of providing a
paint reservoir for use with a spray gun including the steps of: i) providing
a body
open at one end; ii) providing a vacuum forming element that engages the body;
iii) placing the open end in a paint outside the reservoir; iv) forming an at
least partial
vacuum within the body using the vacuum forming element; v) drawing the paint
into
the body by the at least partial vacuum; vi) retaining the paint in the body
until such
time as it is required to be used; and vii) controlling the at least partial
vacuum to
allow the paint to be expelled from the reservoir when connected to the spray
gun
without actuating the vacuum forming element.
According to another aspect, there is provided a method of spraying a
vehicle comprising the steps of: a) preparing a paint mix in a container; b)
forming an
at least partial vacuum within a disposable reservoir of low volume and
withdrawing a
portion of the paint mix from the container into the reservoir by means of
withdrawing
a vacuum forming element that sealably engages the reservoir; c) attaching the
reservoir to a spray gun; d) controlling the at least partial vacuum by
allowing air to
enter the reservoir to allow the paint mix to be withdrawn from the reservoir
without
actuating the vacuum forming element to expel the paint mix and spraying a
test
card; e) comparing the colour of the test card with the colour of the vehicle
to be
spray painted; f) repeating steps (b) to (e) as necessary with adjustments to
the
colour of the paint mix by tinting the paint mix and using a new substantially
identical
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disposable reservoir when preparing each test card until a colour match is
obtained
between the test card and the vehicle; g) charging the spray gun with the
paint mix;
and h) spraying the vehicle.
According to another aspect there is provided a spray gun including the
fluid reservoir as described above.
Brief Description of the Drawings
The invention will now be described, by way of example only, with
reference to the accompanying drawings, in which:
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Figure 1 is a perspective view of a prior, art spray gun, shown partly
disassembled so that it can be filled with paint;
Figure 2 is a perspective view of an alternative prior art paint
reservoir;
Figure 3 is a schematic representation of a `spray out' card;
Figure 4 shows a syringe type paint reservoir according to an aspect
of the present invention, in use, with a bulk paint container;
Figure 5 is a perspective view of the paint reservoir of Figure 4, in
use, with a spray gun;
Figures 6a, 6b are schematic representations of alternative
embodiments of a plunger of the reservoir of Figure 4;
Figure 7 shows a collapsible paint reservoir according to another
aspect of the present invention in an, at least partially, extended
configuration in use with a bulk paint container;
Figure 8 shows the collapsible paint reservoir of Figure 7 in its
collapsed configuration;
Figure 9 shows the paint reservoir of Figures 7 and 8, in use, with a
spray gun;
Figure 10 shows a pipette type paint reservoir according to yet
another aspect of the present invention, in use, with a bulk paint
container;
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Figure 11 shows the paint reservoir of Figure 10, in use with a spray
gun;
Figures 12a, 12b, 12c are schematic representations of alternative
closure mechanisms for a paint reservoir according to any aspect of
the present invention; and
Figures 13a, 13b, 13c are schematic representations of alternative
adapters for a paint reservoir according to the present invention.
Detailed Description of the Preferred Embodiments
Figure 1 of the drawings illustrates a typical prior art paint spray gun 1 of
the gravity-feed type. The gun 1 comprises a body 2, a handle 3 which
extends downwards from the rear end of the body, and a spray nozzle 4 at
the front end of the body. The gun is manually operated by a trigger 5,
which is pivotally mounted on the sides of the gun. The paint reservoir, or
paint pot, 6 which contains paint (or similar material) to be discharged by
the gun, is located on the top of the body 2 and communicates with an
internal passageway (not visible) for compressed air, which extends
through the gun from a connector 7 at the lower end of the handle 3 to the
nozzle 4. In use, the connector 7 is connected to a source of compressed
air (not shown) so that, when the user pulls on the trigger 5, compressed air
is delivered through the gun to the nozzle 4. Because of the atomising
effect of the compressed air, the paint, which is essentially being delivered
under gravity from the pot 6, is delivered through, and from, the nozzle 4
as a spray.
The paint which is contained in the pot 6 is often mixed by hand (for which
a separate receptacle, for example a jug, is required), and poured into the
pot. To ensure that there are no unwanted particles in the paint, which
would spoil the finish of the painted surface, the paint is usually poured
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into the pot 6 through a filter. Figure 1 shows the cap 8 of the pot 6
removed for this purpose, and a conical filter 9 about to be positioned on
the open end of the pot. The filter 9 is shown as being a known type of
disposable conical filter, having solid sides and a filter mesh portion 10 at
the pointed end of the cone. When the pot 6 has been filled with paint, the
filter 9 is removed and discarded, and the cap 8 of the pot is replaced. If
the filter 9 is a reusable filter then, like the gun, it should be cleaned
thoroughly before it is used with a different liquid (e.g. a paint of a
different colour or a liquid having a different chemical composition).
Figure 2 illustrates the components of an alternative form of paint pot 11
which can be used on the gun I of Figure 1 (or any similar gun) instead of
the pot 6, as disclosed in PCT Publication No. WO 98/32539.
The paint pot 11 comprises an open container 12, comparable in size to a
conventional paint pot of a hand-held spray gun, having an air hole 12A in
its base and provided with a disposable liner 13. The liner 13 corresponds
in shape to (and is a close fit in) the interior of the container 12 and has a
narrow rim 14 at the open end which sits on the top edge of the container.
The container 12 also has a disposable lid 15 which is a push-fit in the open
end of the liner 13. The lid 15 has a central aperture 16 from which
extends a connector tube 17 provided, at its end, with outward extensions
18 forming one part of a bayonet connection. The aperture 16 is covered
by a filter mesh 19 which-may be a push fit into the aperture or may be an
integral part of the lid 15. The lid 15 is held firmly in place on the
container 12 by an annular collar 20 which screws onto the container, on
top of the lid.
The paint pot 11 is attached to the spray gun I through the use of an
adapter 21 shown, separated from the paint pot, in Figure 2. The adapter
21 is a tubular component which, at one end 22, is formed internally with
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the other part of the bayonet connection for attachment to the connector
tube 17 of the paint pot 11. At the other end 23, the adapter is shaped to
match the standard attachment of the spray gun paint pot (typically a screw
thread).
The use of the collapsible liner 13 has the advantages that it is not
necessary to clean
the container 12 between uses in order to prevent cross-contamination and its
use
within the container 12 allows the rigidity and ease of handling associated
with these
systems to be maintained.
Figure 4 shows a first embodiment of the present invention in which a
reservoir 30 comprises a syringe body 32 of substantially circular cross-
section and a plunger 34.
The syringe body 32 has a substantially closed end 36 and an open end 38.
The closed end 36 has an annular closure face 39. A cavity 40 extends
between the closed and open ends 36, 38. The body 32 has a small aperture
42 which passes through a wall 44 thereof into the cavity 40 close to the
closed end 36 of the body 32-
The open end 38 of the body 32 has a mounting 46 extending away from
the body 32. The mounting may have either internal or external screw
threads or have plain inner and outer surfaces, see for example Figures 12
and 13.
The plunger 34 has a top plate 50, an elongate shank 52, and a sealing
member 54. The sealing member 54 slidably and sealably engages the
inner surface of the body 32.
The shank 52 passes through the opening in the annular closure face 39
such that the top plate 50 lies externally of the body 32 and the sealing
member 54 lies internally of the body 32. The sealing member 54 can be
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moved in an axial direction towards and away from the open end 38 of the
body 32 by an actuation force applied to the plunger 34 via the top plate 50
externally of the body 32.
The sealing member 54 frictionally engages the wall of the body 32 and is
usually fabricated from an elastomeric material. In effect, the sealing
member 54 divides the cavity 40 into a paint chamber 40a and an air
chamber 40b. The paint chamber 40a lies between the open end 38 and the
sealing member 54. The air chamber 40b lies between the sealing member
54 and the closed end 36. Longitudinal movement of the sealing member
54 within the cavity 40 varies the relative lengths, and hence volumes, of
the paint chamber 40a and the air chamber 40b.
The body 32 of the reservoir 30 is typically formed of a plastics material,
for example polyethylene or polypropylene, and may be transparent,
translucent or opaque and of any suitable size. Typically the body 32 is
formed in an injection moulding process. For use with a paint spray gun as
a colour match test aliquot, a reservoir having a capacity of 25m1, 50m1,
75ml or 100ml is typically used, although other capacities are envisaged for
use dependent upon the intended application. Such other applications may
include the painting of, for example, furniture or signs or the spraying of
other fluids such as adhesives.
The top plate 50 and shank 52 are typically formed of a plastics material,
for example polyethylene or polypropylene and typically are formed in an
injection moulding process.
An adapter 55 is fitted to the reservoir 30 typically either by a friction fit
with the mounting 46 or by use of complementary screw threads on the
adapter 55 and the mounting 46 as described hereinafter, see Figures
13a,b,c. The adapter 55 is arranged to be able to fit directly into the spray
gun I as shown in Figure 5.
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The adapter 55 is typically formed from a plastics material, for example
polyethylene or polypropylene, or alternatively it may be a machined metal
component, for example, formed from aluminium and anodised. The
mounting 46 can be fitted with the adapter 55 to allow the reservoir 30 to
be fitted to a spray gun 1 or with a closure to seal the paint chamber 40a as
described hereinafter, see Figures l2a,b,c.
In use, the plunger 34 is advanced within the cavity 40 to position the
sealing member 54 adjacent to the open end 38. The open end 38 is placed
in a container 56 of paint 57. The plunger 34 is withdrawn to move the
sealing member 54 away from the open end 38 towards the closed end 36.
This withdrawal of the sealing member 54 creates a partial vacuum,
negative pressure compared to atmospheric pressure, within the paint
chamber 40a. This partial vacuum draws the pre-mixed paint 57 from the
bulk container 56 into the paint chamber 40a.
The plunger 34 is withdrawn to a position in which the sealing member 54
is between the open end 38 and the aperture 42 to draw up the required
volume of paint. Air in the air chamber 40b is expelled through the
aperture 42 so movement of the sealing member 54 is not hindered by
compression of the air in the air chamber 40b.
The reservoir 30 is then attached to the spray gun 1 and the plunger 34 is
withdrawn to a position in which the sealing member 54 is between the
aperture 42 and the closed end 36. This allows air to enter the paint
chamber 40a through the aperture 42 releasing the partial vacuum formed in
the body 32 and allows paint to be withdrawn from paint chamber 40a
without a partial vacuum forming therein during the spraying operation. In
this way, the air entering the paint chamber 40a obviates the requirement
for the plunger 34 to move to advance the sealing member 54 to expel the
paint.
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This is advantageous as the pressure differential associated with the
entrainment of the paint into the spray gun air flow may not be sufficient
by itself to draw the plunger 34 into the body due to the sealing fit of the
sealing member 54 in the body. Moreover, if the plunger 34 were to stick
in the body 32 after passing the aperture 42, a partial vacuum may be
formed that reduces or prevents entrainment of the paint into the spray gun
air flow which can result in the spray gun 1 not spraying the paint.
As will now be appreciated, the plunger 34 may be manually operable to
control formation of the partial vacuum to draw fluid into the reservoir 30
and fluid can be drawn from the reservoir 30 without manual operation of
the plunger 34. Moreover, the reservoir 30 is of compact, lightweight
construction that facilitates holding and positioning of the spray gun 1 to
direct the paint spray as desired. As a result, the reservoir 30 is easier and
simpler to use than would be the case if an external actuation force had to
be continuously applied to the plunger 34, ie. by a user's hand, to expel
paint from the reservoir 30.
If desired, an optional filter element 58 can be included in or fitted over
the
open end 38 of the syringe body 32 in order to prevent the entrainment of
particulates into the paint as it is drawn into the body 32. This prevents
particles blocking the spray gun 1 and degrading the characteristics and
finish of the paint 57.
In alternative embodiments, shown in Figures 6a and 6b, the aperture 42
may be omitted and the plunger 34 is provided with a shank 52 having an
internal passageway 59 including a first opening 61 and a second opening
63. The passageway 59 provides an airway that connects the paint chamber
40a to atmosphere externally of the body 32 and is closable by a cover 59a
located on the top plate 50.
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The cover 59a is typically sealingly attached to the outer face of the top
plate 50 of the plunger 34 such that it covers the opening 63 of passageway
59. The cover 59a may either be pivotally mounted upon a. hinge 59b
attached to a side of the top plate 50 (Figure 6a) or frictionally engage the
top plate 50 (Figure 6b).
The cover 59a is attached to the top plate 50 to close the passageway 59 as
paint is drawn into the body 32 so as to prevent air entering the paint
chamber 40a. Air in the air chamber 40b may escape between the shank 52
of the plunger 34 and the opening in the closure face 39. Alternatively, an
aperture may be provided in the wall or closure face for this purpose.
Once the desired paint fill level of the paint chamber 40a has been reached
the
reservoir 30 can be attached to a spray gun 1 as described previously and
cover 59a
removed from the top plate 50. This places the paint chamber 40a in
communication
with atmosphere externally of the body 34 and allows air to enter the paint
chamber
40a releasing the partial vacuum formed therein. Again, this advantageously
allows
paint to be withdrawn from the reservoir 30 during operation of the spray gun
1
without applying any external force to the plunger 34.
In use, the spray gun trigger 5 is depressed and air is drawn from the source
of compressed air (not visible) through the connector 7 which atomises the
paint 57 and passes it out via the spray nozzle 4. Upon completion of spray
painting the reservoir 30 can be removed from the spray gun 1.
if the paint 57 is a match to the desired colour, the paint 57 can be returned
to the bulk container 56 and the reservoir 30 disposed of. Alternatively,
the reservoir 30 can be sealed to store the paint 57 contained within the
chamber 40a for later use.
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If the paint 57 does not match the desired colour it is returned to the bulk
container 56, and tinted further. The reservoir 30 is discarded to prevent
cross-contamination between aliquots of tints. The spray gun 1 is cleaned
and a further aliquot of paint is then drawn up using another reservoir 30
for test spraying in the same manner until a colour match is obtained.
In an alternative embodiment, shown in Figures 7,8 and 9, a collapsible,
concertina-type reservoir 60 is employed and comprises a handle 62
attached to a closed end 64 and a bellows 66 extending between the closed
end and an open end 68.
The closed end 64 seals one end of the bellows 66 so as to form a cavity 69
which opens to its surroundings via the open end 68. The open end 68
includes a mounting 70 which can be fixed to an adapter 55a, as shown in
Figure 9, or have a closure fitted thereto in a similar fashion to the
mounting 46 of the first embodiment.
The bellows 66 are typically made from a plastics material such as
polyethylene or polypropylene. The capacity of the reservoir 60 is
typically 25ml, 50ml, 75ml or 100ml, but it is envisaged that any volume
could be used dependent upon the application for which the reservoir 60 is
to be used.
In use, the bellows 66 of the reservoir 60 are initially in a compressed
configuration, see Figure 8. The end section 68 is inserted into a container
72 of paint 74. The handle 62 is drawn away from the end section 68
thereby extending the bellows 66. As the bellows 66 are extended a partial
vacuum, negative pressure relative to atmospheric pressure, is formed
within the bellows 66. This partial vacuum draws the paint 74 into the
cavity 69, see Figure 7. Extension of the bellows 66 may be operated
manually.
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The bellows 66 may then be attached to a spray gun 1, see Figure 9, and the
paint 74 is withdrawn from the reservoir 60 during operation of the spray
gun 1. In this embodiment, the concertina-type construction of the
reservoir 60 is such that the bellows 66 collapse and return to their
compressed configuration as the paint 74 is withdrawn from the reservoir
60 independently of an external actuation force being applied to the closed
end 64. In this way, the collapse of the bellows 66 controls the partial
vacuum created when drawing paint 74 into the reservoir 60 and ensures
withdrawal of the paint 74 during operation of the spray gun 1 is not
restricted or prevented.
Upon completion of spray painting the reservoir 60 can be removed from
the spray gun 1. If the paint 74 is a match to the desired colour, the paint
74 can be returned to the bulk container 72 and the reservoir 60 disposed
of. Alternatively, the reservoir 60 can be sealed so as to store the paint 74
contained within the cavity 69 for later use.
If the paint 74 does not match the desired colour it is returned to the bulk
container 72, and tinted further. The reservoir 60 is discarded to prevent
cross-contamination between aliquots of tints. The spray gun 1 is cleaned
and a further aliquot of paint is then drawn up using another reservoir 60
for test spraying in the same manner until a colour match is obtained.
If desired, an optional filter element 76 can be included in or fitted over
the
open end 68 of the reservoir 60 in order to prevent the entrainment of
particulates into the paint 74 drawn into the reservoir 60. This prevents the
spray gun 1 being blocked with particles and/or the characteristics and
finish of the paint 74 being degraded by entrained particles.
In another alternative embodiment shown in Figures 10 and 11, a reservoir
80 is employed comprising a pipette body 82 and a filler 84.
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The pipette 82 is substantially circular in cross section and has an elongate
upper section 86, a distended mid-section 88, an elongate lower section 90
with an open end 91 and a mounting 92.
The mounting 92 is the same as that described for the previous
embodiments and can have a closure fitted as described hereinafter or can
be fixed to an adapter 55b that allows the reservoir 80 to be fitted to a
spray gun 1, see Figure 11.
The filler 84 has a generally spherical, elastomeric bulb 94 and a tube 96
extending from the bulb 94 which is open at an end 98 remote from the
bulb 94 and fits on the upper section 86 of the body 82. The tube 96 has a
spur 100 which projects at right angles to the tube 96. The tube 96 has a
valve 102 situated between the end 98 and the spur 100. The spur 100 has
a valve 104 therein.
The pipette 82 is typically made of a plastics material, for example,
polyethylene or polypropylene. Alternatively, the pipette may be made of
glass. The capacity of the reservoir is typically 25m1, 50ml, 75m1 or 100ml,
but it is envisaged that any volume could be used dependent upon the
application for which the reservoir 80 is to be used.
In use, valve 102 is closed and the valve 104 is opened allowing air to be
expelled from the bulb 94 by manual compression of the bulb 94 to force
air from the bulb 94 through the spur 100 and open valve 104. The valve
104 is closed once the desired amount of air has been expelled forming a
partial vacuum, negative pressure when compared to atmospheric, in the
bulb 94.
The open end 91 of the lower section 90 of the pipette 82 is inserted into a
bulk container 106 of paint 108. The valve 102 is opened and the negative
pressure in the bulb 94 draws the paint 108 into the reservoir 80. The valve
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102 is closed when the required volume of paint 108 has been drawn into
the reservoir 80. Typically the major portion of the paint stored in the
reservoir 80 is stored in the mid-section 88.
The reservoir 80 is mounted on the spray gun 1 and trigger 5 is depressed.
Air is drawn from the source of compressed air (not visible) through the
connector 7 and passes to the spray nozzle 4 where it forms a spray of
atomised paint with the paint 108 withdrawn from the reservoir 80. The
valves 102, 104 are opened during the spraying procedure to release the
partial vacuum formed in the pipette body 82 and prevent the formation of
a vacuum within the reservoir 80 which could eventually prevent the
withdrawal of the paint 108 from the reservoir 80. Furthermore, opening
the valves 102,104 allows paint to be withdrawn from the pipette 82
without applying an external force to the bulb 94 during spray painting.
Upon completion of spray painting the reservoir 80 can be removed from
the spray gun 1. If the paint 108 is a match to the desired colour the paint
108 can be returned to the bulk container 106 and the reservoir 80 disposed
of. Alternatively, the reservoir 80 can be sealed so as to store the paint 108
contained within it for later use.
If the paint 108 does not match the desired colour it is returned to the bulk
container 106, and tinted further. The reservoir 80 is discarded to prevent
cross-contamination between aliquots of tints. The spray gun 1 is cleaned
and a further aliquot of paint is then drawn up using another reservoir 80
for test spraying in the same manner until a colour match is obtained.
If desired, an optional filter element 109 can be included in or fitted over
the open end 91 of the reservoir 80 to prevent the entrainment of
particulates in the paint 108 drawn into the reservoir 80. This prevents the
spray gun I being blocked with particles and/or the characteristics and
finish of the paint 108 being degraded by entrained particles.
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In each of the above-mentioned embodiments the respective mountings
46,70,92 may have an internal screw thread 110 engageable with a
complementary external screw thread 120 of a closure 118 (see Figure 12a)
to seal fluid within the reservoir until required for use.
Alternatively the respective mountings 46,70,92 may have an external
screw thread 112 engageable with a complementary internal screw thread
124 of a closure 122 (see Figure 12b) to seal fluid in the reservoir until
required for use.
Alternatively, the mountings 46,70,92 may have plain internal 114 and
external 116 surfaces having no screw threads and a closure 126 is
provided having a smooth external face 128 which is a push-fit to
frictionally engage the internal surface 114 (see Figure 12c) to seal the
fluid in the reservoir 30,60,80.
Figures 13a,13b and 13c show the mountings 46,70,92 of Figures 12a,12b
and 12c with the closures 118,122 and 126 detached and the mountings 46,
70, 92 connected to the appropriate adapter 55,55a,55b for connection to
the spray gun 1.
In Figure 13a, the adapter has an external screw thread 130 engageable with
the internal screw thread 110 of the mounting 46,70,92 and with an
internally threaded portion of the spray gun mounting (not shown).
In Figure 13b, the adapter has an internal screw thread 132 engageable with
the external screw thread 112 of the mounting 46,70,92 and an external
screw thread 134 engageable with an internally threaded portion of the
spray gun mounting (not shown).
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In Figure 13c, the adapter has a smooth outer surface 136 that is a push fit
within the smooth inner surface 114 of the mounting 46,70,92 and an
external screw thread 134 disposed externally of the mounting 46,70,92.
The external screw thread 134 is engageable with an internally threaded
portion of the spray gun mounting (not shown).
Alternatively, the reservoirs 30,60,80 may be. attached to the spray gun
using the bayonet-screw threaded arrangement as disclosed in PCT
Publication No. WO 98/32539 or any in other manner which ensures
interoperability between the system disclosed therein and reservoirs made
according to the present invention.
The reservoir according to this invention may be used in instances where
only a small amount of paint is required so as to minimise usage and
wastage of paint. For example, when spray painting a test card to obtain a
colour match or when spray painting small areas of a vehicle or other
object.
It will be appreciated that the disposable nature of a reservoir according to
this invention greatly reduces the amount of cleaning associated with prior
art systems thereby making the changing of colours much easier and
quicker. This is of particular importance when trying to obtain a colour
match that may require many iterations of tinting to achieve a match.
It will further be appreciated that the disposable nature of a reservoir
according to this invention and the associated reduction in cleaning will
reduce the amount of solvents used with attendant benefits both to users
health and the environment.
Other uses of a reservoir for delivering small volumes of a fluid to a spray
gun in a variety of applications will be apparent to those skilled in the art.
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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 to produce any desired reservoir and/or reservoir
spray gun combination.
Moreover, while the specific materials and/or configuration of the
reservoirs 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 spirit and scope of the claims.
28
