U.S. patent application number 15/528324 was filed with the patent office on 2017-11-16 for elastic element for a device for dispensing fluids or mixtures and method and mould for making said elastic element.
This patent application is currently assigned to TAPLAST S.p.A.. The applicant listed for this patent is TAPLAST S.p.A.. Invention is credited to Evans SANTAGIULIANA.
Application Number | 20170326567 15/528324 |
Document ID | / |
Family ID | 52355113 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170326567 |
Kind Code |
A1 |
SANTAGIULIANA; Evans |
November 16, 2017 |
ELASTIC ELEMENT FOR A DEVICE FOR DISPENSING FLUIDS OR MIXTURES AND
METHOD AND MOULD FOR MAKING SAID ELASTIC ELEMENT
Abstract
The invention concerns an elastic element (100) made of a
plastic material for a device (1) for dispensing fluids (L),
comprising a tubular body (129) that develops around a main
longitudinal axis (X), comprising a main portion that develops
according to a spiral-shaped pattern and extends longitudinally
between a first end portion (100a) and a second end portion (100b)
opposite the first end portion (100a). One of the first and second
end portions comprises a first projection (151) extending from the
internal surface of the tubular body (129) towards the inner space
defined by the tubular body (129). The invention furthermore
concerns a method for making an elastic element (100) through an
injection moulding process, a mould (200) for making an elastic
element (100).
Inventors: |
SANTAGIULIANA; Evans;
(Vicenza (VI), IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAPLAST S.p.A. |
Dueville-Povolaro (VI) |
|
IT |
|
|
Assignee: |
TAPLAST S.p.A.
Dueville - Povolaro (VI)
IT
|
Family ID: |
52355113 |
Appl. No.: |
15/528324 |
Filed: |
November 18, 2015 |
PCT Filed: |
November 18, 2015 |
PCT NO: |
PCT/IB2015/058915 |
371 Date: |
May 19, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 33/446 20130101;
B29K 2995/0046 20130101; B05B 11/3074 20130101; B29C 45/262
20130101; B29L 2023/00 20130101; B29K 2023/06 20130101; B29C
45/2681 20130101; B29C 45/2602 20130101; B05B 11/3077 20130101;
B05B 11/3001 20130101; B29C 45/44 20130101; B29K 2023/12 20130101;
B05B 11/3067 20130101; B05B 11/3023 20130101; B29C 2045/4078
20130101 |
International
Class: |
B05B 11/00 20060101
B05B011/00; B05B 11/00 20060101 B05B011/00; B29C 45/26 20060101
B29C045/26; B05B 11/00 20060101 B05B011/00; B29C 45/44 20060101
B29C045/44; B29C 45/26 20060101 B29C045/26; B29C 45/26 20060101
B29C045/26 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2014 |
IT |
VI2014A000301 |
Claims
1. An elastic element (100) made of a plastic material for a device
(1) for dispensing fluids (L), comprising a tubular body (129) that
develops around a main longitudinal axis (X) having a longitudinal
direction, said tubular body (129) comprising an internal surface
(150), an inner space defined by said tubular body (129) and at
least one main portion that develops according to a spiral-shaped
pattern and extends along the longitudinal direction between a
first end portion (100a) and a second end portion (100b) opposite
said first end portion (100a), wherein at least one of said first
and second end portions comprises at least one first projection
(151) extending from the internal surface of said tubular body
(129) towards the inner space.
2. The elastic element (100) according to claim 1, wherein said at
least one first end portion (100a) comprises a tubular portion with
a substantially cylindrical inner wall (150) that extends along the
longitudinal direction from said main portion developing according
to a spiral-shaped pattern, and in that said at least one first
projection (151) extends from said substantially cylindrical inner
wall (150).
3. The elastic element (100) according to claim 1, wherein said at
least one first projection (151) extends along a direction that is
substantially perpendicular to said main longitudinal axis (X).
4. The elastic element (100) according to claim 1, wherein said at
least one first end portion (100a) comprises a plurality of first
projections (151) arranged at substantially regular intervals from
one another along said internal surface (150) of said tubular
body.
5. The elastic element (100) according to claim 1, wherein said
second end portion (100b) of said tubular body (129) opposite said
first end portion (100a) comprises at least one second projection
(153) extending along a direction that is substantially parallel to
said main longitudinal axis (X).
6. The elastic element (100) according to claim 5, wherein said at
least one second projection (153) extends from an end wall that is
substantially perpendicular to said main longitudinal axis (X)
towards the outside of said tubular body (129).
7. The elastic element according to claim 6, wherein said end wall
is in the shape of an annulus.
8. A method for making an elastic element (100) via an injection
molding process, said method comprising the following steps:
providing a mold (200) suitable for injection molding comprising a
hollow die (204) and a male punch (206) rotatably arranged inside
said die (204) in such a way as to define an interspace (I) in a
shape corresponding to that of an elastic element (100) having
first projections (151) and second projections (153) between said
hollow die (204) and said male punch (206); injecting plastic
material in a pasty state into said interspace (I); and removing
said male punch (206) by rotating it on its longitudinal axis,
wherein during rotation of said punch (206) at least one of said
first projections and said second projections (151, 153) of said
elastic element (100) becomes engaged in a corresponding seat
created in said mold (200), so that said elastic element (100)
cannot be rotated by said punch (206).
9. The method according to claim 8, wherein said mold (200)
comprises a housing bush (207) for said male punch (206), in which
said male punch (206) is rotatably accommodated, and in that during
rotation of said male punch (206) at least one of said first
projections (151) becomes engaged in a corresponding seat provided
in said housing bush (207).
10. The method according to claim 9, wherein said mold (200)
comprises an injection unit (205) suited to be positioned proximal
to said interspace (I) so as to allow a plastic material in the
pasty state to be injected into said interspace (I), and during
rotation of said punch (206) at least one of said second
projections (153) becomes engaged in a corresponding seat provided
in said injection unit (205).
11. A mold (200) suitable for making an elastic element (100)
according to claim 1, said mold (200) comprising at least one
rotatable male punch (206) defining a longitudinal rotation axis,
and at least one hollow die (204), said at least one rotatable male
punch (206) and said at least one hollow die (204) being suited to
be mutually positioned so as to define an interspace (I) in a shape
corresponding to that of an elastic element (100), wherein said
mold (200) comprises at least one cavity suited to receive a
portion of a plastic material in a pasty state intended to be used
to make at least one of said first projections and said second
projections (151, 153), said at least one cavity thus defining at
least one seat in which at least one of said first projections and
said second projections (151, 153) can become engaged during
rotation of said punch (206) around said longitudinal rotation
axis.
12. The mold according to claim 11, wherein said mold (200)
comprises at least one housing bush (207) in which said male punch
(206) is rotatably accommodated, and said at least one cavity is
defined by said housing bush (207), said at least one cavity thus
defining a seat in which at least one of said first projections
(151) can become engaged during rotation of said punch (206) around
said longitudinal rotation axis.
13. The mold according to claim 12, wherein said mold comprises an
injection unit (205) suited to be positioned at the level of said
interspace (I) so as to allow a plastic material in a pasty state
to be injected into said interspace (I), and in that said injection
unit (205) comprises at least one second cavity suited to
accommodate a portion of a plastic material in a pasty state
intended to be used to make at least one of said second projections
(153), said at least one second cavity thus defining a seat in
which at least one of said second projections (153) can become
engaged during rotation of said punch (206) around said
longitudinal rotation axis.
14. The mold according to claim 11, wherein said die is formed by
two complementary portions (204a, 204b) suited to be translated in
two opposite senses of translation along a direction of translation
that is substantially perpendicular to the longitudinal rotation
axis of said male punch (206).
15. The mold according to claim 11, wherein said mold (200)
comprises a movable portion (203) suited to be translated in two
opposite senses of translation along a direction that is
substantially parallel to said longitudinal rotation axis of said
male punch (206).
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The invention concerns an elastic element for a device for
dispensing fluids, said device being suited to be applied to a
container that holds the fluid itself, the device being in
particular suited to dispense food substances, perfurmes or
detergents in general, even atomized or in the form of foam. The
invention concerns also a method and a mould for making an elastic
element of the type described above.
DESCRIPTION OF THE STATE OF THE ART
[0002] As is known, dispensing devices that are applied to the
container holding the product to be dispensed are widely used to
dispense liquid or creamy products such as food substances, soaps,
creams, detergents or perfumes.
[0003] Said devices are substantially constituted by a cap provided
with means suited to be coupled to the neck of the container and
with a hollow body that defines a fluid suction/compression
chamber, also called accumulation chamber, which is slidingly
coupled to a piston.
[0004] The piston comprises a plunger and a rod, the latter being
provided with an actuator element also called spout or nipple and
suited to be operated by the user. In order to dispense a
predetermined quantity of the fluid contained in the device, the
user presses the actuator element, and thus the piston, shifting it
from an initial rest position to a second and final operating
position.
[0005] During said pressing step, the predetermined quantity of
fluid flows out of a suitable duct associated with the spout.
[0006] Once the fluid has been dispensed, the operator releases the
actuator element that, together with the piston, automatically
returns to the initial rest position.
[0007] In order to allow said automatic return movement, the device
advantageously comprises an elastic element associated with the
piston and with the actuator element, which is compressed and
loaded while the user exerts a pushing action, thus pressing it,
while it releases the piston when the user leaves hold of the
actuator.
[0008] Preferably, in the initial rest position of the actuator and
the piston, the elastic element is maintained in a pre-load
condition. This means that the elastic element is assembled in a
slightly compressed condition, in order to generate a pre-load
force on the piston and thus maintain it in its rest position in a
stable manner. Therefore the user, acting on the actuator, exerts a
pressing force that makes it possible to dispense the fluid present
in the suction/compression chamber and also to load (compress) the
elastic element associated with the piston.
[0009] The resistance to compression exerted by the elastic
elements normally used in the known technique increases as
compression increases, so that also the force required by the user
increases as compression increases.
[0010] For example, in the case of metallic helical springs the
compression force develops linearly and increasingly with respect
to the degree of compression exerted.
[0011] This is an inconvenience for the user, who needs to press
the actuator with an increasingly higher pushing force in order to
be able to dispense the product effectively.
[0012] Furthermore, the force exerted during the release step in
order to move the piston back to the rest position is smaller than
the force exerted by the user during compression, the degree of
compression being the same.
[0013] The result of this effect, also known as hysteresis of the
elastic element, is that a given quantity of energy is lost between
the steps of compression and release of the elastic element, with
the risk that the piston and the actuator element associated with
it are not brought back to the correct initial rest position.
[0014] In the attempt to at least partly overcome the drawbacks
described above, elastic elements made of a plastic material were
proposed in the past, which were obtained through a blowing or
injection moulding process; the high elastic memory coefficient of
the plastic materials makes it possible, in fact, to give the
elastic elements the desired characteristics of elasticity.
[0015] Furthermore, another factor that allows the desired
elasticity characteristics to be obtained is represented by the
shape of the elastic elements, wherein the most performing shapes
can be obtained through blowing and/or injection moulding
techniques.
[0016] However, in the case of elastic elements made of a plastic
material, it is their production that entails some problems, as,
for example, the choice of the most performing plastic materials in
terms of elastic response is limited due to the problems generated
by the same materials during the blowing and/or injection moulding
process.
[0017] In fact, the most performing elastic materials pose the
problem that the removal of the elastic element from the mould is
difficult, as the most performing elastic materials tend to adhere
and therefore to remain attached to the mould itself.
[0018] It is thus the object of the present invention to at least
partly overcome the drawbacks summed up above.
[0019] In particular, it is an object of the present invention to
provide a solution for the production of elastic elements in a
plastic material that allows plastic elastic elements with
satisfying elastic characteristics (equal or at least approximating
the ideal elastic characteristics) to be obtained, wherein the
process for making said elastic elements is not complicated by the
plastic characteristics of the materials but on the contrary allows
the widest range of plastic materials to be selected.
[0020] In further detail, it is another object of the present
invention to propose a solution for making plastic elastic elements
of the type mentioned above that makes it possible to easily remove
the elements from the respective moulds.
SUMMARY OF THE PRESENT INVENTION
[0021] The present invention is based on the general consideration
according to which the drawbacks of the solutions of the known art
can be overcome or at least minimized by selecting and producing
plastic elastic elements in a suitable shape. In particular,
according to a further consideration on which the present invention
is based, by conveniently selecting the shape (and possibly the
size) of the elastic element it is possible to give the elastic
element the desired elastic characteristics and also to facilitate
the removal of the element from the respective mould, and this
almost without any limitation to the choice of plastic
materials.
[0022] According to a first embodiment, the subject of the present
invention is an elastic element made of a plastic material for a
device for dispensing fluids according to claim 1, meaning an
elastic element in a plastic material comprising a tubular body
that develops around a main longitudinal axis, said tubular body
comprising at least one main portion developing according to a
spiral-shaped pattern and extending along the longitudinal
direction between a first end portion and a second end portion
opposite said first end portion, wherein at least one of said first
and second end portions comprises at least one first projection
extending from the internal surface of said tubular body towards
the inner space defined by said tubular body.
[0023] According to a construction variant, said at least one end
portion comprises a tubular portion with a substantially
cylindrical inner wall that extends in the longitudinal direction
from said main portion developing according to a spiral-shaped
pattern, wherein said at least one first projection extends from
said substantially cylindrical inner wall.
[0024] If necessary, said at least one first projection extends
along a direction that is substantially perpendicular to said main
longitudinal axis (X) and said at least one end portion may
comprise a plurality of first projections arranged so that they are
spaced from each other at substantially regular intervals along
said internal surface of said tubular body.
[0025] According to a further construction variant, said second end
portion of said to tubular body opposite said first end portion
comprises at least one second projection that extends along a
direction substantially parallel to said main longitudinal
axis.
[0026] Preferably, said at least one second projection extends from
an end wall that is substantially perpendicular to said main
longitudinal axis towards the outside of said main body and/or said
end wall is in the shape of an annulus.
[0027] The subject of the present invention includes also a method
for making an elastic element in a plastic material through an
injection moulding process, said method comprising the following
steps: [0028] providing an injection moulding press comprising a
hollow die and a male punch rotatably arranged inside said die in
such a way as to define an interspace between said die and said
punch, in a shape corresponding to that of said elastic element;
[0029] injecting plastic material in the pasty state into said
interspace; [0030] removing said punch by rotating it around its
longitudinal axis,
[0031] wherein during the rotation of said punch at least one of
said first and second projections of said elastic element becomes
engaged in a corresponding seat provided in said mould, so that
said elastic element cannot be set rotating by said punch.
[0032] If necessary, said mould may comprise a bush suited to house
said punch, in which said punch is rotatably accommodated, and
wherein during the rotation of said punch at least one of said
first projections becomes engaged in a corresponding seat provided
in said housing bush.
[0033] Furthermore, said mould may comprise an injection unit
suited to be positioned at the level of said interspace in such a
way as to allow said plastic material in the pasty state to be
injected into said interspace, wherein during the rotation of said
punch at least one of said second projections becomes engaged in a
corresponding seat provided in said injection unit.
[0034] According to the present invention, furthermore, a mould is
provided that is suitable for making an elastic element in a
plastic material, said mould comprising at least one rotatable male
punch defining a longitudinal rotation axis and at least one hollow
die, said at least one male punch and said at least one hollow die
being suited to be mutually positioned in such a way as to define
said interspace in a shape corresponding to that of said elastic
element, wherein said mould comprises at least one cavity suited to
receive the portion of said plastic material in the pasty state
intended to be used to make at least one of said first and second
projections, said at least one cavity thus defining at least one
seat in which at least one of said first and second projections can
become engaged during the rotation of said punch around said
longitudinal rotation axis.
[0035] If necessary, said mould may comprise at least one housing
bush in which said male punch is rotatably accommodated, wherein
said at least one cavity is defined by said housing bush, said at
least one cavity thus defining a seat in which at least one of said
first projections can become engaged during the rotation of said
punch around said longitudinal rotation axis.
[0036] If necessary, said mould may comprise an injection unit
suited to be positioned at the level of said interspace in such a
way as to allow said plastic material in the pasty state to be
injected into said interspace, wherein said injection unit
comprises at least one second cavity suited to accommodate the
portion of said plastic material in the pasty state intended to be
used to make at least one of said second projections, said at least
one second cavity thus defining a seat in which at least one of
said second projections can become engaged during the rotation of
said punch around said longitudinal rotation axis.
[0037] Possible further embodiments of the present invention are
defined in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Further advantages, objectives and characteristics of the
present invention, as well as further embodiments of the same, are
defined in the claims and highlighted here below through the
following description, with reference to the attached drawings; in
the drawings, corresponding or equivalent characteristics and/or
component parts of the present invention are identified by the same
reference numbers. In particular, in the drawings:
[0039] FIG. 1 shows a longitudinal sectional view of an example of
a device for dispensing fluids or mixtures comprising the elastic
element that is the subject of the invention;
[0040] FIG. 2 shows a side view of the elastic element according to
an embodiment of the present invention;
[0041] FIG. 3 shows a longitudinal sectional view of the element of
FIG. 2;
[0042] FIG. 3A shows an enlarged detail of FIG. 3;
[0043] FIG. 4 shows the curve of some characteristic measures of
the elastic element of FIG. 2;
[0044] FIGS. 5A and 5B respectively show a side view and a
longitudinal sectional view of a further embodiment of the elastic
element according to the present invention;
[0045] FIGS. 6A and 6B show each a perspective view of an elastic
element according to an embodiment of the present invention;
[0046] FIG. 7 shows a longitudinal sectional view of an elastic
element according to a further embodiment of the present
invention;
[0047] FIGS. 8 and 9 show perspective views of two embodiments of
the elastic element according to the present invention;
[0048] FIG. 10 shows a longitudinal sectional view of an elastic
element according to a further embodiment of the present
invention;
[0049] FIGS. 11A, 11B, 11C and 11D show a schematic view of a mould
according to the present invention and the steps of the method
according to the present invention;
[0050] FIG. 12 sums up the elasticity characteristics of the
elastic element according to the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0051] The examples of embodiment of the invention described below
refer to an elastic element for a device for dispensing fluids and
in particular for dispensing detergent fluids, wherein, however,
the proposed solution can be applied also to devices for dispensing
perfumes or food products or any other fluid in general that must
be drawn from a container and conveyed towards the outside even
atomized or in the form of foam.
[0052] An example of a device 1 for dispensing fluids applied to
the neck N of a container C containing a fluid L to be dispensed is
shown in FIG. 1.
[0053] It comprises a hollow body 2 that defines a
suction/compression chamber 3 for the fluid L, provided with a
suction duct 4 for the fluid L, which is slidingly coupled with a
movable piston 5 (from top to bottom and vice versa with reference
to the figure) that moves between a first rest position, visible in
FIG. 1, and at least one second operating position, not represented
in the figures.
[0054] The device 1 can be operated by the user through an actuator
element 6 comprising an operating button also called spout or
nipple 7, which is integral with the piston 5.
[0055] The hollow body 2 is integral with a ring nut 16 that
supports and guides the piston 5. The support ring nut 16 is in
turn associated with a bearing element 17 suited to be applied to
the neck N of the container C. In the embodiment shown herein an
inner thread 17a allows said application.
[0056] Once the dispensing operation has been completed, an elastic
element 100 made of a plastic material ensures the return of the
piston 5 from the operating position to the rest position.
[0057] The elastic element 100 is interposed between the bearing
element 17 and the actuator element 6 and thus with its first end
100a counteracts the bearing element 17 and with its second end
100b, opposite the first end 100a, counteracts the actuator element
6.
[0058] The first end 100a of the elastic element 100 is housed in a
suitable seat 17b created in the bearing element and, analogously,
the second end 100b of the elastic element 100 is housed in a
suitable seat 6a created in the actuator element. As regards the
piston 5, this comprises a supporting element 5a slidingly coupled
with a plunger 5b that sealingly cooperates with the walls of the
suction/compression chamber 3.
[0059] The supporting element 5a is coupled through interference
with a rod 12 that is integral with the actuator element 6.
[0060] The supporting element 5a and the rod 12are provided with a
dispensing duct 13 suited to dispense the fluid L and communicating
with the suction/compression chamber 3 and with the external
environment E.
[0061] First valve means 14 arranged downstream of the suction duct
4 and second valve means 15 arranged upstream of the dispensing
duct 13 regulate the flow of the fluid L from the container C to
the suction/compression chamber 3 and its flow from the chamber 3
to the dispensing duct 13.
[0062] In the example of embodiment illustrated herein, the first
valve means 14 comprise a ball 14a made of a non-metallic material,
while the second valve means 15 are constituted by sealing edges
15a belonging to the plunger 5b and suited to cooperate with the
supporting element 5a and with the walls of the suction/compression
chamber 3 and to become engaged in corresponding grooves obtained
in the support and guide ring nut 16.
[0063] The operation of the dispensing device 1 is described here
below with reference to FIG. 1.
[0064] From the operating point of view, the user acts on the
actuator element 6 by exerting a certain amount of pressure P that
moves the piston 5 axially (downwards in the figure).
[0065] In this way, the user loads the elastic element 100 and
compresses the product contained in the suction/compression chamber
3.
[0066] The increased pressure makes the plunger 5b slide on the
supporting element 5a, thus allowing the fluid L contained in the
suction/compression chamber 3 to flow out, first towards the
dispensing duct 13 and then towards the outside E.
[0067] Once the plunger 5b has reached the bottom of the
suction/compression chamber 3, it is released by the user, thus
allowing the elastic element 100 to bring it back to the initial
rest position shown in FIG. 1.
[0068] The elastic return of the piston 5 generates a negative
pressure inside the suction/compression chamber 3 and this causes
the first valve means 14 located downstream of the suction duct 4
to intervene and the fluid L to flow into the chamber itself,
drawing it from the container C and preparing the device 1 for the
successive dispensing operation.
[0069] The elastic element 100 carried out according to an
embodiment of the invention is described here below with reference
to FIGS. 2 and 3.
[0070] The elastic element 100 comprises a side wall 128 that
extends over a predetermined length H between the first end or
bottom end 100a of the elastic element 100 and its second end or
top end 100b.
[0071] The length H thus defines the size of the elastic element
100.
[0072] The side wall 128 develops around a main longitudinal axis X
so as to enclose it completely, except for the upper and lower
openings 128a and 128b at the level of the respective bottom end
100a and top end 100b, as shown in FIG. 3.
[0073] On the elastic element 100 it is possible to determine the
parameter D0, as shown in FIG. 3, identified as the distance
defined by the external surface of the side wall 128 of the elastic
element 100 on an axis that is perpendicular to the main axis X and
passes through the mid-point Hm of the height H. The parameter D0
represents, therefore, the outer diameter in the median area of the
elastic element 100.
[0074] The side wall 128 of the elastic element 100 thus defines a
substantially tubular body 129 with a main portion included between
the two opposite ends 100a and 100b and developing according to a
spiral-shaped pattern.
[0075] As can be observed in the longitudinal sectional view of
FIG. 3, said spiral-shaped pattern defines for the side or external
wall 128 an alternation between external apices 131 and internal
apices 130.
[0076] Each external apex 131 is connected to a corresponding
adjacent internal apex 130 by a connecting portion 132.
[0077] The connecting portions 132 susbtantially develop according
to the same pattern and preferably comprise a curved section 133,
as shown in FIG. 3A. Preferably, the curved section 133 comprises
an arc of a circle with radius R. The curvature radius R of the arc
of a circle 133 is selected based on the value of the parameter D0
and is preferably included between 0.15*D0 and 0.60*D0, more
preferably included between 0.25*D0 and 0.45*D0, and even more
preferably equal to 0.35*D0.
[0078] Advantageously, the selection of said curvature radiuses for
the arc of a circle of the curved section 133 makes it possible to
reduce to a minimum the stroke necessary to place the elastic
element 100 in the pre-load condition, that is, the condition in
which it is slightly compressed in order to generate a preload
force on the piston 5 so as to maintain it in its rest position in
a stable manner.
[0079] In the embodiment of the invention described herein, the
curved sections 133 along the elastic element 100 between the first
end 100a and the second end 100b have a substantially constant
curvature radius R.
[0080] In variant embodiments of the invention, however, the curved
sections 133 along the elastic element 100 between the first end
100a and the second end 100b can have different curvature
radiuses.
[0081] The internal apices 130 are substantially arranged on a
hypothetical internal surface of internal envelope Yi that forms an
angle A with the main longitudinal axis X, as shown in FIG. 3.
[0082] Preferably, the angle A between the internal envelope
surface Yi and a plane perpendicular to the main longitudinal axis
X is included between 78.degree. and 88.degree., more preferably
included between 81.degree. and 85.degree. and even more preferably
equal to 83.degree..
[0083] Analogously, the external apices 131 are substantially
arranged on an external envelope surface Ye that forms an angle B
with the main longitudinal axis X, as indicated in FIG. 3.
[0084] Preferably, the angle B between the external envelope
surface Ye and the main longitudinal axis X is included between
78.degree. and 88.degree., more preferably included between
81.degree. and 85.degree. and even more preferably equal to
83.degree..
[0085] The shape given to the elastic element 100 is thus
substantially the shape of a truncated cone.
[0086] Advantageously, the choice of said angle A between the
internal envelope surface Yi and the main longitudinal axis X and
the choice of the angle B between the external envelope surface Ye
and the main longitudinal axis X makes it possible to reduce the
overall dimensions of the elastic element 100 in the compressed
condition.
[0087] In fact, in the compressed condition of the elastic element
100, the internal apices 130 and the external apices 131 of the
external side wall 128 are in offset and not superimposed positions
and therefore the turns that make up the external side wall 128
interpenetrate one another.
[0088] The external side wall 128 of the elastic element 100 has a
substantially constant thickness S.
[0089] The thickness S is selected based on the value of the
parameter D0 and is preferably included between 0.01*D0 and
0.04*D0, more preferably included between 0.02*D0 and 0.03*D0 and
even more preferably equal to 0.025*D0.
[0090] Advantageously, the choice of the thickness S makes it
possible to optimize the ratio between elastic force and minimum
hysteresis of the material.
[0091] The distance D1 between two adjacent internal apices 130 is
selected based on the value of the parameter D0 and is preferably
included between 0.01*D0 and 0.5*D0, more preferably included
between 0.02*D0 and 0.04*D0 and even more preferably equal to
0.032*D0.
[0092] The distance D2 between two adjacent external apices 131 is
selected based on the value of the parameter D0 and is preferably
included between 0.01*D0 and 0.5*D0, more preferably included
between 0.02*D0 and 0.04*D0 and even more preferably equal to
0.032*D0.
[0093] Advantageously, the choice of said distance D1 between two
adjacent internal apices 130 and of said distance D2 between two
adjacent external apices 131 makes it possible to optimize the load
of the elastic element 100 with respect to its size when it is
compressed.
[0094] The elastic element is made of a plastic material, such as
polypropylene, polyethylene or TPE (thermoplastic elastomer).
[0095] The tensile modulus of said material is preferably included
between 50 Mpa and 300 Mpa, more preferably included between 80 Mpa
and 220 Mpa.
[0096] Advantageously, the choice of the value of the tensile
modulus makes it possible to optimize the hysteresis value of the
material used, thus reducing the size of the elastic element
100.
[0097] The hardness of the material of which the elastic element
100 is made is preferably included between 20 and 70 Shore D, more
preferably included between 35 and 60 Shore D and even more
preferably equal to 45 Shore D.
[0098] FIG. 4 shows the characteristic curve of an elastic element
100 according to the invention, with length H equal to 29 mm,
wherein R=7.4 mm, S=0.5 mm, D1=6.8 mm, D2=6.8 mm, A=6.8.degree.,
B=6.8.degree., and which is made of TPE (thermoplastic
elastomer).
[0099] This curve shows the development of the loading force of the
elastic element 100 (y-axis B) with respect to the degree of
compression of the elastic element 100 (x-axis A). The curve
represents a complete cycle constituted by a compression phase We
and a release phase Wd of the elastic element 100.
[0100] In particular, the elastic element 100 is subjected to a
maximum compression Cm of approximately 17.5 mm and then
released.
[0101] The values indicated in the diagram show how during the
compression phase We the elastic element 100 has a central area
with compression values included between Ci=5 mm and Cf=13 mm with
substantially ideal characteristics, meaning that for a
considerable portion the loading force applied is substantially
constant and has a value FC of approximately 2.3 Kgf.
[0102] The elastic element 100 is mounted on the dispensing device
1 in such a way that it operates in an ideal manner and thus
between said limit compression values included between Ci and
Cf.
[0103] In particular, in the rest condition shown in FIG. 1, the
elastic element 100 will be in a slightly compressed pre-load
condition, with a compression value Ci equal to 5 mm.
[0104] Analogously, in the condition of maximum compression, the
elastic element 100 will be in a compressed condition with a
compression value Cf equal to 13 mm. It should finally be noted
that the hysteresis of the elastic element 100 of the invention is
advantageously reduced. In fact, the value of the hysteresis D
given by the difference between the loading force Fc during the
compression phase We and loading force Fd during the release phase
Wd is reduced.
[0105] Preferably, the amplitude of the hysteresis D is maintained
at values lower than half the maximum compression force Fcmax of
the elastic element corresponding to the value of maximum
compression Cm, that is, preferably D.ltoreq.0.5*Fcmax.
[0106] More preferably, the amplitude of the hysteresis D is
maintained at values lower than one fourth of the maximum
compression force Fcmax of the elastic element corresponding to the
value of maximum compression Cm, that is, D.ltoreq.0.25*Fcmax.
[0107] According to a construction variant not represented herein,
the elastic element of the invention may comprise two portions
substantially in the shape of a truncated cone, adjacent to and
opposing each other.
[0108] According to a further embodiment of the invention not
represented herein, the connecting portion 132 between the external
apex 131 and the adjacent internal apex 130 develops according to a
substantially mixtilinear pattern, comprising a first curved
section 133, preferably an arc of a circle, and a second
substantially linear section.
[0109] According to a further embodiment of the elastic element of
the invention not represented herein, at the level of the external
apices 131 and of the internal apices 130 the external side wall is
thicker, so as to define a rib for said apices. Said rib makes the
external side wall more resistant at the level of the apices 130
and 131, the latter being subjected to continuous stress during
compression and release of the elastic element while it is being
operated.
[0110] A description of a further embodiment of the elastic element
according to the present invention is provided here below with
reference to FIGS. 5A, 5B, 6A and 6B.
[0111] It is clear from the figures that the elastic element 100
represented therein always comprises a main tubular body 129
substantially in the shape of a truncated cone, similar to that
present in the embodiment previously described, constituted by a
side wall 128 that develops around a main longitudinal axis X, in
such a way as to define an internal space. The main tubular body
129 comprises in particular a main portion that develops according
to a spiral-shaped pattern extending in the longitudinal direction
(along a direction parallel to the axis X) between a first end
portion 100a and a second end portion 100b opposite said first end
portion 100a. The main characteristic of this embodiment lies in
that, at the level of the first end portion 100a, a plurality of
projections 151 extend from the internal surface of the side wall
128 (of the main body 129) towards the inside of the main tubular
body 129, the function of said projections being to facilitate the
process of production of the elastic element 100 (in particular,
through injection moulding), as clarified in greater detail below.
In particular, the projections 151 extend from the substantially
cylindrical internal surface 150 of the first end portion 100a. In
the specific case represented herein, the cross section of the
projections (perpendicular to the direction of extension) is
substantially rectangular and they substantially extend along a
direction that is perpendicular to the axis X. Furthermore, the
projections 151 are arranged at regular intervals from each other
along the internal surface 150. Obviously, however, the extension,
the cross section, the number, the mutual distance etc. of the
projections 151 can be changed and selected according to the needs
and/or circumstances.
[0112] The main difference between the embodiment shown in FIG. 7
and those previously described lies in the shape of the main
tubular body 129 (which always comprises a main portion developing
according to a spiral-shaped pattern), which is no longer that of a
truncated cone but is substantially cylindrical, the angles A and B
previously described with reference to FIG. 3 being in this case
substantially equal to 90.degree.. In fact, during the development
of the present invention, it emerged that the presence of the
projections 151 facilitates the production process of the elastic
element and thus makes it possible to choose among the widest range
of plastic materials, wherein some of said materials allow
elasticity characteristics that otherwise would be possible only
for truncated-cone shaped elements to be ensured also for
substantially cylindrical elements.
[0113] A further important embodiment of the elastic element 100
according to the present invention is provided here below with
reference to FIG. 8.
[0114] The elastic element 100 of FIG. 8 is substantially similar
to those of the embodiments already described above concerning the
shape and the structure of the main tubular body 129, but however
is different from them due to the fact that, in this case, it is
the second end portion 100b (opposite the first end portion 100a)
that comprises a plurality of projections 153 that extend along a
direction substantially perpendicular to the direction of extension
of the first projections 151 and therefore along a direction of
extension substantially parallel to the main axis X. In particular,
said second end portion 100b of the tubular body 128 opposite the
first end portion 100a comprises an end wall 152 that is
substantially perpendicular to said main longitudinal axis X that
extends towards the outside of said main body 128. The shape of
said end wall in plan view (seen from above) substantially
corresponds to the shape of an annulus and the second projections
153 extend from the surface 152 towards the outside of the main
tubular body 128. As the function of the second projections 153 is
substantially similar to that of the first projections 151, the
same function will be clarified in greater detail below. Obviously,
also in this case, the extension (both along the direction parallel
to the axis X and along the direction perpendicular to the axis X),
the cross section, the number, the mutual distance etc. of the
projections 153 may be changed and selected according to the needs
and/or circumstances.
[0115] The specific feature of the further embodiment of the
elastic element 100 according to the present invention represented
in FIG. 9 is constituted by the shape of the first projections 151
that protrude from the internal surface 150, in this case similar
to the shape of the teeth of a gear.
[0116] Finally, in the embodiment illustrated in FIG. 10 there are
practically all of the solutions described above, meaning that the
elastic element 100, in this case, comprises both the first
projections 151 at the level of the first end portion 100a and the
second projections 153 at the level of the second end portion 100b,
protruding from the end wall 152.
[0117] A mould according to the present invention for the
production of an elastic element made of a plastic material
according to the present invention is described here below with
reference to FIGS. from 11A to 11D.
[0118] The mould 200 represented in the figures comprises at least
one rotatable male punch 206 that defines a longitudinal rotation
axis substantially coinciding with the axis X of the elastic
element to be made, wherein the male punch 206 comprises a
substantially cylindrical end portion housed in a seat having a
corresponding shape and created in a fixed support 201 of the mould
200, and an intermediate portion, also substantially cylindrical
(or partially slightly in the shape of a truncated cone) housed in
a correspondingly shaped seat in a housing bush 207, in turn
accommodated in a correspondingly shaped seat defined by a second
fixed support 202 of the mould 200 superimposed to the first fixed
support 201, and by a third support 203 that is movable with
respect to the support 202 between the two positions respectively
represented in FIGS. 11A (resting on the support 202) and 11B
(detached from the support 202). In practice, the punch 206 can be
rotated within the bush 207, which on the contrary is kept steady
by the supports 201 and 202. The mould 200 furthermore comprises a
die 204 constituted by two shells 204a and 204b suited to be
positioned as shown in the figures with respect to the helical end
of the punch 206, that is, in proximity to the helical end of the
punch 206, in such a way as to define an interspace I in a shape
corresponding to that of the elastic element 100 to be made (closed
position in FIGS. 11a and 11d), wherein the two shells 204a and
204b can be moved away from the helical end of the punch 206 and
placed in to the open position shown in FIG. 11B.
[0119] It should furthermore be noted that the bush 207 (see FIG.
11D) comprises an end portion that extends outside of the support
203 (when this is resting on the support 202) and inside the die
204, wherein the projecting end of the bush 207 helps define the
shape of the lower end of the interspace I and thus of the first
lower end 100a of the elastic element 100. Said projecting end of
the bush 207 comprises in particular a plurality of first cavities
(defined by its external surface opposite the internal surface
adjacent to the punch 206) which, while the elastic element 100 is
being moulded, are filled with plastic material and thus define the
first projections 151 of the elastic element described above.
[0120] In the same way, the surface of the injection unit 205
intended to come into contact with the die 204 comprises a
plurality of second cavities which, while the elastic element 100
is being moulded, are filled with plastic material and thus define
the second projections 153 of the elastic element 100, this further
variant being thus suitable for making an elastic element 100 as
shown in FIGS. 8 and/or 10.
[0121] The moulding method according to the present invention can
be summed up as follows.
[0122] With the mould 200 in the configuration shown in FIG. 11A,
the plastic material in the pasty state is injected in the
interspace I through the injection unit 205, in a quantity
sufficient to fill the interspace.
[0123] During the successive step, possibly once the plastic
material has conveniently cooled down (at this point it has become
the elastic element), the die 204 is opened and then the punch 206
is rotated around its longitudinal axis. At this point, due to the
inevitable tendency of the plastic material to adhere to the
spiral-shaped end of the male punch 206, the male punch, rotating,
would tend to set rotating also the elastic element 100, with
obvious and serious inconveniences. On the other hand, thanks to
the presence of the first projections 151 of the elastic element
that are now engaged in the corresponding first cavities of the
bush 207 (fixed), the elastic element cannot be set rotating and
will thus be released (if necessary by shifting the movable support
203 upwards) so that it can be removed.
[0124] Obviously, the sequence of the operations just described
above can be modified according to the needs and/or circumstances,
as it is possible, for example, to open the die 204 after setting
the punch 206 rotating. In the same way, it will be possible to
move the injection unit 205 away before or after setting the punch
206 rotating and/or opening the die 204, or even to maintain the
unit 205 resting on the die 204.
[0125] The method according to the present invention is also
suitable for making elastic elements according to the embodiments
illustrated in FIGS. 8 and 10, in Is particular by proceeding as
follows.
[0126] In this case, as already described above, the injection unit
must comprise a plurality of second cavities which, while the
elastic element 100 is being moulded, are filled with plastic
material and thus define the second projections 153 of the elastic
element 100.
[0127] With an injection unit of this type and with the mould 200
in the configuration shown in FIG. 11A, the plastic material in the
pasty state is injected into the interspace I through the injection
unit 205, in a quantity sufficient to fill the interspace.
[0128] During the successive step, possibly once the plastic
material has conveniently cooled down (at this point it is the
elastic element), the punch 206 is rotated around its longitudinal
axis (before or after opening the die 204 but always with the
injection unit 205 engaged with the elastic element 100). Also in
this case, due to the inevitable tendency of the plastic material
to adhere to the spiral-shaped end of the male punch 206, the male
punch, rotating, would tend to set rotating also the elastic
element 100, with obvious and serious inconveninces. On the other
hand, thanks to the presence of the second projections 153 of the
elastic element that are now engaged in the corresponding second
cavities of the unit 205, the elastic element cannot be set
rotating and will thus be released (if necessary by shifting the
movable support 203 upwards after opening the die 204) so that it
can be removed.
[0129] It has thus been shown, through the above description of the
embodiments of the present invention illustrated in the drawings,
that the present invention allows the set objects to be achieved.
In particular, the invention makes it possible to provide an
elastic element for a device for dispensing fluids that
approximates as much as possible the ideal characteristics during
compression and release and allows the production process of such
an elastic element to be simplified.
[0130] In particular, the "elastic" characteristics of the elastic
element according to the present invention are indicated in FIG. 12
and in the following table, wherein FIG. 12 and the following table
show that the present invention, thanks to its shape and to the
process selected for its production, makes it possible to select
the material among the widest range of materials with different
hardnesses, while otherwise the choice would certainly be reduced
due to the limitations of the methods of the known art that have
already been summed up above.
TABLE-US-00001 Standard stroke considered: 12 mm Elastic response
values (N) for 12 mm stroke vs hardness (ShD) Hardness 40 ShD 45
ShD 50 ShD 55 ShD .DELTA. ShD -- 5 5 5 Force (N) 14 17.5 21.8 27.3
.DELTA. force (%) 0 25% 25% 25%
[0131] In particular, FIG. 12 and the table above show how, as the
hardness of one of the possible materials selected (TPE) varies,
the elastic response of the element is proportional to the
variation of the hardness itself.
[0132] In particular, it can be understood that the elastic
response and the hardness of the material are strictly related: for
every 5-point increase (in ShD) in hardness the result is an
increase of approximately 25% in elastic response.
[0133] Even though the invention has been described making
reference to the attached drawings, upon implementation it may be
subjected to modifications that must all be protected by the
present patent, provided that they fall within the same inventive
concept expressed in the following claims.
* * * * *