Note: Descriptions are shown in the official language in which they were submitted.
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PCT/NL99/00761 3 K EB/DL/Afa3
ZQ F
PRECOMPRESSION SYSTEM
The invention relates to a precompression
system for placing between a pump and a discharge nozzle
that are connected by a conduit debouching in a space,
the system comprising a precompression valve movable
between a position closing of:f the connection in which it
abuts a seat on the mouth of the conduit and a position
releasing the connection in which it is spaced from the
seat, the precompression valve being biased to the
closing position by spring means. Such a precompression
system is known from e.g. the US Patent No. 5,730,335.
The known precompression system is used in a
sprayer head for a container, for instance a bottle
containing liquid detergent. Such a sprayer head is
formed by a body in which a rrtanually operable piston pump
is arranged. This pump is operated by a trigger that is
pivotally connected to the body. The suction side of the
pump is connected-to a tube that extends into a bottle
over a substantial length, usually nearly to the bottom
thereof, and through which liquid may be drawn out of the
bottle. The compression side of the pump is connected to
the discharge nozzle of the sprayer head through a
conduit. Between the pump and the conduit leading to the
discharge nozzle is arranged the precompression system,
comprising a precompression v:alve that is kept shut by
spring means and that is open'ed only when a predetermined
pressure is attained within the pump. The precompression
valve has for its object to prevent the fluid from
leaving the discharge nozzle at too low a pressure, which
would result in too large drops being formed in the
spray. In order to achieve an optimum spraying pattern
the liquid must in fact be pressed out of the discharge
nozzle at a predetermined and relatively high pressure.
The known precompression system comprises an
end part of the cylinder wall of the pump, which
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debouches in an annular space. The rim of the cylinder
wall constitutes a seat ontowhich a resiliently flexible
diaphragm is pressed. This diaphragm is pressed shut by
spring pressure, which in the diaphragm of this older
patent is generated by the flexion stresses in the
material of the diaphragm itself. When the pressure in
the pump cylinder becomes high enough the diaphragm will
be lifted from the seat whereby pressurized liquid may
flow from the cylinder to the conduit leading to the
discharge nozzle. When nearly all liquid has been pressed
from the cylinder and the pressure therein drops again,
the diaphragm will return to the closing position in
which it comes to rest against the seat again as a result
of the internal spring force.
The known precompression system has the
drawback that the annular space is arranged in-line with
the pump cylinder. It is therefore difficult to design
this known precompression system such that it can be
manufactured by injection molding, and furthermore the
resulting design becomes relatively bulky, thus making it
hard to incorporate in a compact sprayer head. In the
above-mentioned US patent 5,730,335 the pump
incorporating the precompression system is arranged under
an angle between the suction tube and the spraying tube
for manufacturing reasons, which res.ults in a complex
structure that is hard to assemble_
Embodiments of the invention therefore has for an
object to provide a precompression system of the type
described above, which is easier to make and assemble than the
conventional precompression system, and which therefore
offers a greater freedom of design when integrating it
into a compact sprayer head. According to the present
invention this is achieved in that the space is connected
to the pump and the conduit is connected to the discharge
nozzle. By thus reversing the direction of flow in
comparison to the known precompression systems, a
precompression system is obtained that need not be placed
in-line with the pump cylinder, but may for instance be
i i
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arranged next to the cylinder. In this way the design of the sprayer head may
be
substantially simplified, the head may be made more compact and will be
simpler
and better suited for manufacturing. Furthermore, this has for its result that
the
cylinder and piston need not be placed under an angle, which is advantageous
for
the operation thereof.
Thus, in one aspect, there is provided a precompression system for
placing between a pump and a discharge nozzle, the system comprising a conduit
and a space connecting the pump and the discharge nozzle, the space being
connected to the pump and the conduit being connected to the discharge nozzle,
the conduit including a mouth debouching in the space, the space being at
least
partially annular and at least partially surrounding the end of the conduit,
the
system further including a precompression valve movable between a position
closing off the connection in which the valve abuts a seat on the mouth of the
conduit and a position clearing the connection in which the valve is spaced
from
the seat, the precompression vaive being biased to the closing position by
spring
means, wherein the spring means is integrated in the precompression valve, the
spring means and the precompression valve being constituted by a resiliently
flexible diaphragm, the system further including a substantially cylindrical
sleeve
bordering the at least partially annular space and integrally molded with the
diaphragm.
The spring means are preferably integrated in the precompression
valve, for instance in that the precompression valve and the spring means are
constituted by a resiliently flexible diaphragm. In this way a structurally
simple
valve is obtained. The diaphragm is preferably domed, so that it has a stable
and
suitably tensioned position of rest.
The precompression system preferably includes a stop member
cooperating with the diaphragm whereby bending of the diaphragm is limited and
the diaphragm is prevented from "flipping over" to another stable position at
a
greater distance from the seat, from which it would then not return. The stop
member is preferably integrally formed with the diaphragm.
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Furthermore, the.space is preferably at least
partially annular and least partially surrounds the end
of the conduit, so that a simple circular diaphragm may
be employed. The part of the conduit surrounded by the
annular space and the pump may each have a centre line,
these centre lines being substantially parallel but
offset with respect to each other.
The annular space is preferably bordered by a
substantially cylindrical sleeve. In this way a proper
seal is obtained and leakage may be prevented_ The
diaphragm and the sleeve may be integrally molded,
thereby further reducing the number of parts and thus
simplifying assembly of the system.
At least one suction opening closable by a
valve is arranged in the sleeve for drawing in the liquid
to be sprayed. When the shut-off valve is integrally
formed with the sleeve, the number of separate parts is
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even further reduced and manufacture and assembly of the
precompression system even further simplified.
The invention further relates to a spraying
device comprising a pump having a suction side and a
compression side, means connected to the suction side of
the pump for supplying a fluid to be sprayed, a discharge
nozzle connected to the compression side of the pump and
a precompression system of the type described above
arranged between the pump and the discharge nozzle.
Finally, the invention relates to an assembly
constituted by a container and a spraying device as
described above.
The invention will now be illustrated by means
of an example, with reference being made to the annexed
drawings, in which:
Figure 1 is a perspective view of an assembly
constituted by a container and a spraying device in which
the precompression system of the invention may be used;
Figure 2 is a perspective exploded view of the
sprayer head of the assembly of Figure 1 incorporating
the precompression system;
Figure 3 is a partly cut away perspective view
of the sprayer head of Figure 2 during a pump stroke;
Figure 4 is a view corresponding to Figure 3 of
the sprayer head during a return stroke;
Figure 5 is a detailed view of the
precompression system in the direction of the arrow V in
Figure 3;
Figures 6A and 6B are longitudinal sections
through the precompression system at the onset and the
end of the pump stroke, respectively, and;
Figure 7 shows a schematic perspective detailed
view of an alternative embodiment of a valve used in the
precompression system.
Fig. 8 shows a longitudinal section of an
alternative embodiment of the precompression system, and
Fig. 9 shows a detail of this embodiment of the
pre-compression system.
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A sprayer head 1 for a container 2 comprises a
pump 3 having a suction side 5 and a compression side 6.
Movable operating means 4 are connected to the pump 3, in
the illustrated example constituted by a trigger 13
5 having a continuous pivot shaft 53 that is received in a
hollow space 54 in a frame 22 carrying the pump 3 and
that is locked therein by a flexible snap arm 55. Means 7
are connected to the suction side 5 of the pump 3 for
supplying a fluid from the container, comprised of a
conduit having its free end connected to a tube 23
extending into the container. The compression side 6 of
the pump 3 is connected to a discharge nozzle 8 through a
conduit 9.
As the shaft 53 of the trigger 13 and the
receiving space 54 are located above the spraying conduit
9, an aperture 56 is arranged in the trigger 13, through
which extends the end of this conduit 9, onto which is
arranged the discharge nozzle 8.
Pump 3 is a piston pump, constituted by a pump
housing or cylinder 10 and a piston 11 reciprocating
therein. The piston 11 is connected to the trigger 13. In
order to return the piston 11 and trigger 13 to their
extended position of rest at the end of a pump stroke,
the sprayer head 1 comprises biasing means 16. In the
illustrated embodiment the biasing means are constituted
by a pair of parallel flexion springs 17 that engage ribs
at the inside of trigger 13. When the trigger 13 is
pivoted around the pivot shaft 53 towards the pump 3 and
presses the piston 11 into the cylinder 10 during a pump
stroke the springs 17 are bent. When the pressure on the
trigger 13 is released it is forced back to its position
of rest by the springs 17 flexing back. Since the trigger
is connected to the piston 11 such as to remain fixed
under both tension and compression, the piston 11 is then
also pulled back to its position of rest. The connection
between the trigger 13 and the piston 11 is a snap
connection formed by protrusions 14 of the trigger 13
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being snapped into corresponding openings 28 in the
piston 11.
Between the cylinder 10 and the spraying
conduit 9 a precompression system is arranged comprising
a space 58, which in the illustrated embodiment is
annular, connected to the cylinder 10 and an end part of
the spraying conduit 9 debouching therein, which are
closed off in a gas- and liquid-tight manner by a
resiliently flexible domed diaphragm 59. The space 58 is
bordered by a cylindrical sleeve 60 that is received in a
cavity 61 in the frame 22 and that is integrally formed
with the diaphragm 59 in the illustrated embodiment. In
this cylindrical sleeve 60 an opening 15 is formed, in
which is arranged a valve, and which is connected to the
suction tube 7 for the fluid through an opening 67 in the
frame 22. This valve 63, which is also integrally formed
with the sleeve 60, is movable, in the shown embodiment
pivotable between a position in which it hermetically
seals the opening 67 (Figs. 3, 4, 6A) and a position in
which this opening 67 is left clear (Fig. 5, 68). Further
a stop member 64 is connected to the diaphragm 59, which
serves to limit bending of the diaphragm 59 and to
prevent it from "flipping over". The cylindrical sleeve
60 is locked in the cavity 61 of the frame 22 by an end
wall 65 which in the shown embodiment is integrally molded
with the container 2. The cylindrical sleeve 60 further
includes a reinforcing flange 75 by which deformation of
the sleeve 60 under the influence of the pump pressure in
the cylinder 10 and thus the risk of leakage along the
sleeve 60 is prevented.
In a preferred embodiment (fig. 7) the shut off
valve 63 is connected to the cylindrical sleeve 60 by
means of a pair of pivotable and stretchable f-shaped
arms 68 having one end 69 attached to the sleeve 60 and
the other end connected to the valve body 63. During a
return or suction stroke of the pump 11 the arms 68 are
pivoted upward and stretched somewhat, whereby the valve
body 63 is lifted from the opening 67 over a height L.
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In yet another preferred embodiment (fig. 8)
the cylindrical sleeve 60 does not include an opening
which is connected to the suction tube 23. Instead the
sleeve 60 has a slightly outwardly extending peripheral
edge part 70 close fittingly lying against the wall of
the cavity 61. The peripheral edge portion 70 is
relatively flexible and includes a slightly inclined
inner surface 73. The sleeve 60 further includes a part
71 having a reduced diameter and bordered on one side by
the flexible edge part 70 and on the other side by the
cylindrical part of the sleeve 60. Together'with the wall
of the cavity 61 the reduced diameter part 71 defines an
annular space 72 which is in fluid communication with the
opening 67.
During a pump stroke of the piston 11 the fluid
pressure acting on the inclined inner surface 73 of the
peripheral edge part 70 will force this part inwards in
the direction of the wall of the cavity 61, thus
resulting in an excellent sealing along the entire
perifery of the cavity 61. On the other hand, the suction
behind the piston 11 during a return or suction stroke
and the atmospheric pressure in the container 2 will lead
to a pressure differential over the peripheral edge part
70, forcing this inwards, away from the wall, and leading
to a fluid communication being established between the
annular space 72, which is in direct connection with the
interior of the container 2 via the suction tube 23, and
the cylinder 10.
In this way the peripheral edge part 70
functions as a valve having excellent sealing properties.
Due to the sealing action of the peripheral edge part 70
the pump pressure does not act on the cylindrical part of
the sleeve 60, so that the risk of leakage of fluid along
the cylindrical part and the annular sealing ridges 74
connected thereto is reduced. Furthermore the sleeve 60
may be constructed smaller and less heavy than in the
previous embodiments, as there is no need for a
reinforcing flange along the peripheral edge. Furthermore
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this embodiment of the sleeve 60 may simply be
manufactured by means of injection moulding, as the
elimination of an opening in the side wall and the
corresponding valve has for its result that there is no
need for slides or mandrels in the mould. Finally, the
sleeve 60 may also be installed more easily, as it is
wholly symetrical in rotational direction around the
center line, and lacks an opening that should be aligned
with the opening 67.
The precise shape of the peripheral edge part
70 of the sleeve 60 is not critical, as the sole
requirement is that it should exert sufficient pressure
on the wall of the cavity 61 to ensure a perfect sealing
during a pump stroke, and should be lifted from the wall
at any point along its periphery during a suction stroke.
Obviously, the shape of the edge part 70 and of the wall
should further be selected such, that they define an
annular space. Therefore, the angle of inclination of the
peripheral edge part is somewhat smaller in an
alternative embodiment (fig. 9), whereas the wall of the
cavity has a larger inclined part, leading to
substantially the same volume for the annular space 72.
The precompression system 40 serves in known
manner to inhibit transport of fluid from the container 2
to the discharge nozzle as long as a predetermined pump
pressure is not yet attained. If a fluid is sprayed
through the nozzle 8 at too low a pressure, this fluid is
insufficiently atomized and drops generated in the spray
cone are too large. In order to prevent this from
occurring the connection between the container 2 and the
discharge nozzle 8 is closed off by the diaphragm 59
which is forcibly pressed against the rim 66 of the
spraying conduit 9 serving as a seat due to the internal
stress determined by the domed configuration and assisted
by the ambient pressure behind the diaphragm 59. only
when sufficient pressure, for instance on the order of 3
bar, is built up in the cylinder 10 by moving the piston
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11 to its end position will the diaphragm 59 be lifted
from the seat 66.
The sprayer head 1 thus functions as follows.
when a user wishes to atomize the fluid from the
container 2, he first pulls the trigger 13. In this way
air that is present in the cylinder 10 and that cannot
flow back to the container 2 due to the opening 67 being
shut off by the valve 63 is compressed by the piston 11.
When the pressure of the air is high enough at the end of
the pump stroke the diaphragm 59 is lifted from the seat
66 and the air may escape.
During the subsequent return stroke forced by
the biasing means 16 fluid is drawn from the container 2
through tube 23, conduit 7 and openings 62 and 67 into
the cylinder 10 until this is completely filled at the
end of the return or suction stroke (Fig. 6A). In order
to prevent a partial vacuum from being developed in the
container 2 during this stroke an aeration hole 51 is
formed in the wall of the cylinder 10, which is opened
when an outer peripheral sealing lip 39B passes the
opening 51 during inward movement of the piston 11 and
which is again connected to a closed space defined
between the outer and inner peripheral sealing lips 39B
and 39A of the piston 11 during the outward stroke of the
piston 11.
When the trigger 13 is then pulled again the
pressure within the cylinder 10 will rise very quickly as
the fluid is hardly compressible. In this way the
diaphragm 59 is lifted from the seat 66 virtually
instantly and the fluid may be pressed through the space
between the diaphragm 59 and the seat 66 to the spraying
conduit 9 and thence to the discharge nozzle 8 (Fig. 6B)
where it is atomized.
Since in accordance with the present invention
the annular space 58 is connected to the pump cylinder 10
and the conduit 9 debouching therein is connected to the
discharge nozzle, instead of the other way around as in
conventional precompression systems, the annular space 58
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need not be aligned with the cylinder 10, but may be
offset as illustrated. The sprayer head may thus be
efficiently manufactured by injection molding so that the
design may be kept compact.
5 Although the invention has been illustrated
above on the basis of an embodiment thereof, it will be
apparent that it is not limited thereto. The diaphragm
and sleeve could for instance be formed separately. Also
the stop member might possibly be obviated in some cases,
10 while the choice of materials may of course be varied as
well. The scope of the invention is thus defined solely
by the appended claims.
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