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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a spray pump of the type comprising: a main
cylinder in which there is defined a pumping chamber; a main piston
mounted to slide in said main cylinder between a first inactive position
and a second end-of-stroke position, said piston being extended by a
hollow rod and having a valve seat therein; first spring means urging said
piston to said first position; a secondary cylinder comprised within the
main cylinder; a secondary piston mounted to slide within said secondary
cylinder between a first closed position and a second open position, said
piston being provided with an upper extension having an end applicable
against said valve seat; and second spring means urging said secondary
piston to said first position thereof.
2. Description of the Prior Art
Frequently in ordinary daily life, it is necessary to spray liquids of
quite diverse viscosities towards certain surfaces or spaces. This need is
observed, for example, during personal toilet operations to spray lotions,
scented waters, deodorants or other products on the human body; and also
for domestic cleaning, as also for spraying insecticides, air fresheners,
etc.
On such occasions, a strong spray is required, without the intensity
thereof being weak at the start or end of the spraying operation since, in
this case, the spray is preceded and/or followed by a weak jet which does
not attain the desired objective and, therefore, is wasted or even may
produce undesired effects, such as stains, drips, etc.
Pumps producing a precompression of the product to be dispensed are already
know and the result of said precompression is to allow the vigorous spray
mentioned above.
Some of the known pumps are provided with a single spring or resilient
means fulfilling two missions, i.e. of causing the piston to recover the
starting position thereof after the pump has been operated and of
providing the desired precompression; these pumps, therefore, have the
drawback of not allowing the recovery speed or conditions and the degree
of precompression to be adjusted separately.
The operation of another type of known pumps, as indicated at the
beginning, is based on a predetermined ratio between the force of the two
spring means provided, such that one of the springs may not be altered
unilaterally, without substantially altering the operation of the pump or
even preventing it from working.
Since is not possible to change the corresponding resilient means or
springs freely or independently in the known, pumps, their field of
application becomes, therefore, limited, obliging the manufacture of
different pumps for different applications, thereby preventing the
manufacture of long runs with the logical effect on costs.
Finally, a third group of pumps having independently replaceable springs
may be cited. Nevertheless, these other known pumps suffer various
drawbacks, such as a premature, albeit limited communication of the
pumping chamber with the outside.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a pump in which the said
drawbacks are overcome, while retaining at all times the advantages
derived from the precompression of the product to be dispensed.
The above object is attained by a pump of the type mentioned at the
beginning, characterised in that there is a fixed connection between said
main piston and said secondary cylinder, forming a space having closed
bottom and an open upper end through which the pumping chamber and the
space are in communication.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages and features of the invention will be appreciated from
the following description in which there is described without any limiting
nature, a preferred embodiment of the invention, to be read with reference
to the enclosed drawings, in which:
FIG. 1 is an axial sectional view of a spray pump showing the inactive
position of the main piston.
FIG. 2 is a similar sectional view to the previous one, showing the
end-of-stroke position of the main piston.
FIG. 3 is a cross sectional view of the widened portion of the upper open
end of the secondary cylinder and of the portion of the axial extension of
the main piston.
FIG. 4 is an elevation view of the lower portion of the main piston with
the axial extension thereof.
DETAILED DESCRIPTION OF THE INVENTION
The pump of the invention comprises spray and actuating means 2 which are
not described in detail because they are conventional and are not
necessary for an understanding of the invention. Said means 2 includes a
cap 4, a spray member 6 and means 8 for coupling the assembly to the rest
of the pump, particularly to the rod 10 of the main piston 12, to be
referred to hereinafter.
A body 14 and a cap 16 allow the pump to be connected to the container, not
shown, of the material to be sprayed. A seal 18 of appropriate material
seals the joint.
Held by said body 14 there is a shell 20, formed by an upper wide portion
22, by a main cylinder 24 having a lower narrower portion 26 and by a
portion 28 for attachment to a dip tube 30, shown in part, and which
places the pump in communication with the bottom of the said container.
There is an annular shoulder 31 between the cylinder 24 and portion 26.
In the lower portion 26 there is a stopper member which in the example
shown in a moving disc 32 adapted to close an orifice 34. A perforated
cover 36 restricts the movbility of the disc 32, so that it is in a
position to fulfil the stopping mission when required.
The cylinder 24 and part of the lower portion 26 define a pumping chamber
37 and the main piston 12 slides along the cylinder 24. The piston is
provided with an upper flap 38 and a lower flap 40 bearing against the
inner surface of the cylinder 24. The piston 12 is generally tubular and
is provided with a transverse wall 42 provided with an orifice 44 having a
valve seat 46 formed at the lower end thereof. As stated above, the main
piston 12 is extended at the upper end thereof with the hollow rod 10
which places the spray means 6 in communication with the pumping chamber
and said main piston may slide between an inactive position (FIG. 1) and
an end-of-stroke position (FIG. 2) to be referred to hereinafter.
The main piston 12 is provided with a longitudinal extension 48 extending
downwardly from said piston, and said extension 48 is provided with
openings 50, the purpose of which will be described hereinafter. In the
embodiment shown, said longitudinal extension is seen to be formed by
longitudinal strips completely separated from one another by the
corresponding openings 50; nevertheless, the invention includes other
embodiments not shown which fulfil the purpose which, as said, is
described hereinafter.
The pump is also provided with a secondary cylinder 52 which is comprised
inside the main cylinder 24. The secondary cylinder 52 forms a space 54
which has a closed bottom end 56 and an open upper end, preferably defined
by a widened portion or bowl 58 of the secondary cylinder 52.
The said widened portion 58 snugly surrounds an end portion of the
longitudinal extension 48, whereby there is a fixed attachament between
the main piston 12 and the secondary cylinder 52, whereby the movement of
the piston 12 implies movement of the cylinder 52 and vice versa. To
facilitate said fixed attachment, there contemplated first annular means
within the widened portion 58 mating with second external annular means 60
on the longitudinal extension 48, both being mutually engageable.
It is to be noted that the attachment between these two members does not
close all the apertures 50, but the part of the apertures 50 closest to
the lower flap 40 remain open. Consequently there is a communication
between the pumping chamber 37 and said space 54. The embodiment shown is
simply an example, since the invention contemplates any other type of
fixed attachment between the piston 12 and the secondary cylinder 52 which
at the same time ensures the communication between the pumping chamber 37
and the space 54.
First spring means 62, preferably a coil spring, urge the main piston 12 to
the first inactive position thereof.
In the embodiment shown, the coil spring extends between the annular
shoulder 31 and the start of the widened portion 58 of the secondary
cylinder.
There is also provided a secondary piston 64 adapted to slide in the said
secondary cylinder 52, between a first closed position and a second open
position. The secondary piston 64 is provided with an upper extension 66
having a free end 68 which may bear against the valve seat 46, in which
case it stoppers the orifice 44. Second spring means 70 urge the secondary
piston to the first closed position thereof. To this end said means bears
against the bottom 56 and the secondary piston itself.
The secondary piston 64 may be solid, although it is preferably hollow,
having therefore an axial cavity 72. This configuration allows the air to
be removed from the secondary cylinder 52 during the assembly of the pump.
Furthermore, when the secondary piston is slightly defective, part of the
liquid to be sprayed penetrates to the bottom of the secondary cylinder
and the liquid is expelled through the cavity 72 while the pump is
operating. Obviously this explusion could not take place if the piston
were solid.
The main cylinder 24 is provided in the interior thereof with small cells
74 which are engaged by the lower flap 40 the main piston 12 when it
reaches the second position thereof. In this way a circuit is formed for
expelling the air when priming the pump. Other orifices and passages are
to be found in the pump to make the circulation of air towards the
interior of the container possible, so as to replace the volume of liquid
removed in each case. Nevertheless, such members are not described as not
being directly associated with the invention.
The pump operates as follows. Once it has been primed, the means 2 are
actuated, whereby a downwardly directed force is applied to the main
piston 12 resulting in the formation of pressure in the liquid occupying
the chamber 37, obviously without the liquid being compressed. Since the
chamber 37 is in communication with the space 54, the pressure created is
applied to the secondary piston 64. When this pressure is sufficient to
overcome the force of the second spring means 70, said secondary piston 64
descends and, therefore the end 68 of the extension 66 moves away from the
valve seat 46. This opens up and exit path for the liquid to the outside
and said exit is maintained whilever the operating force is applied to the
means 2 and until the bottom 56 of the secondary cylinder 52 abuts the the
perforated cover 36. It should be observed that during this stage, the
pressure created in the liquid holds the disc 32 closing the orifice 34,
whereby the liquid may not flow back to the container. Furthermore, it
should also be noted that when the passage is opened to the liquid to the
outside, liquid is already precompressed, whereby the liquid exits with
force and without weak drippings being caused. Such drops do not occur at
the end either, since when the liquid pressure tends to diminish, the
force of the second spring means 70 prevails and the pump is rapidly
closed again.
When the pump actuating means are released (apart from closing the orifice
44), the first spring means 62 recover, whereby the main piston 12 rises,
causing a depression which separates the cover 32 from the orifice 34 and
the liquid in the container fills the pumping chamber 37 again, so as to
be able to start a new liquid spray operation cycle.
The aforedescribed pump is also provided with a special peculiarity
residing in the fact that the two spring means 62 and 70 are completely
independent. In fact, the actuation of the first spring means 62 depends
only on the force applied to the means 2, without the greater or lesser
strength of the second spring means 70 having any influence. Therefore,
the first spring means 62 may be selected in each case depending on the
greater or lesser viscosity of the liquid (possibly a paste) and bearing
in mind also the friction within the pump. Furthermore, the desire to have
a "hard" or a "soft" pump may be satisfied.
For the same reasons, the second spring means 70 may be selected in each
case depending on the higher or lower degree of precompression desired for
the pump.
Therefore, the pump of the invention is suitable for a wide range of liquid
viscosities and also for a wide range of precompression values, the only
thing being required in each case is to fit the appropriate springs. It is
obvious that this peculiarity allows a large number of like pumps to be
manufactured (the springs varying according to the end purpose of the
pumps), with the consequent cheapening of costs.
Finally, it is pointed out that the pump of the invention maintains the
communication of the bottom of the secondary piston with the atmosphere
always, provided that the secondary pump 64 is hollow.
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