Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
208034'
HINGED SNAP CLOSURE MADE OF PL~rSTICS MATERIAL
The present invention relates to a plastic snap hinge
closure consisting of a lower part and of an upper part connected
with it by means of a film hinge, where the closure shell walls in
the area of the hinge extend straight or curved and have at least
one tension element connected with both closure parts in one
piece, and that the at least one tension element has, directly or
indirectly, an attachment point on the shell walls of both parts
Plastic snap hinge closures of the above mentioned type are
known, for example, from the two European Patent Disclosures Nos.
0 147 423 and 0 291 457 of applicant. In the first mentioned
patent disclosure the tension elements are tension straps, which
are produced by means of injection molding over consoles on the
shell wall of the lower part and of the lid and thus are located
in one plane. In the second patent disclosure mentioned the
tension straps are disposed extending approximately in or on the
shell wall.
In the first mentioned example the said tension straps
extend in one plane in the closed position and the attachment
points of the tension straps are displaced out of the shell wall
by consoles in such a way that they are located parallel to the
main axis. In the second example mentioned the tension straps
extend in two planes which between them enclose an angle.
Accordingly, the outer sections of each of the tension straps must
travel a greater distance during opening than the inner sections
of the straps located more closely to. the hinge.
In a third variant in accordance with European Patent
Disclosure No. 0 056 469 (Wiesinger), instead of tension straps
triangular intermediate elements, which verge with their tips into
the main hinge, were disclosed.
Regarding an explanation of the operation of the various
snap hinge closures, it was believed that the tension straps used
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in the two first mentioned patent disclosures would elastically
stretch and in this way provide the snap effect. In fact,
however, the plastic materials used for plastic closures hardly
have the ability of stretching elastically. This means that the
snap effect really does not work in this way.
The function in connection with the third variant in
accordance with European Patent Disclosure No. 0 056 469 is
correctly explained. Here it is pointed out that the action of
the snap closure is based on the elastic defarmation of the
closure in the area of the hinge. This means that in the course
of each opening or closing of the closure the shell wall of the
lower part or the lid, or of the entire lid, arches in the area of
the passage across the dead center position in the course of
operation and subsequently is bent back into the relaxed, non-
deformed ,shape.
Of course, this is an undesirable cooperation of forces
which are hard to predict and interact in a complex manner. The
attainment of the snap action can only be determined empirically
and is hard to predict. Easier to predict are the results in
connection with snap closures operating by means of a toggle
joint, one of the levers of which extends into the surface of the
lid and the other in the shell wall of the lid and the lower
part. With these closures the snap effect depends on the force
required to deform the two levers of the toggle joint. However, a
hinge of this type is only suitable for closures having a small
spout, where the lid itself does not close off the spout, but a
sealing element placed thereon and cooperating with the spout
does, since the lid itself can not seal because of the cuts along
the toggle joint.
Accordingly it is desired to provide snap hinge closures,
the snap effect of which does not depend on the elastic of some
arbitrary part of the closure, except for the tension element.
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CA 02080347 2002-11-15
3
It is an object of the present invention to provide a
plastic snap hinge closure where the snap effect can be
attained by means of the at least one tension element.
The present invention provides a plastic snap hinge
closure having at least one first film hinge connecting a
lower part and an upper part, and at least one tension
element having two opposite end portions each attached to a
corresponding closure wall of each of the lower part and
the upper part, the snap hinge closure further comprising a
second film hinge and a third film hinge per each the at
least one tension element, the second film hinge formed
between the upper part and each the at least one tension
element, the third film hinge formed between the lower part
and each the at least one tension element, wherein the at
least one tension element comprises a plurality of adjacent
partial sections forming a strap in a closed position of
the hinge closure, wherein each the strap lies within a
plane defined substantially between the second film hinge
and the third film hinge in the closed position, wherein
the adjacent partial sections meanders through a plurality
of curved turns within the plane, and wherein during a
pivotal movement of the upper part with respect to the
lower part, about an axis of rotation of the at least one
first film hinge, each the partial section elastically
deforms to cause a change in a length of each the partial
section.
Further advantageous embodiments of the subject of the
invention will be explained in the following description by
means of the drawings, wherein:
CA 02080347 2000-04-25
- 3a -
Fig. 1 is a ~~chemat:ic functional description of the
snap effect of a snap hinge closure in accordance with the
invention, equipped with a longitudinally changeable
tension element;
Figs. 2a and 2b are perspective views of a round snap
hinge closure to explain the disposition of the tension
elements or of the tension element in relation to the main
hinge;
Figs. 3 to 5 show three different embodiments of
length-adjustable tension elements at round closures, in
the variation a. each in a back lateral view towards the
hinge of the closed closure and in b. each in the
completely opened state of the same snap hinge closures;
Fig. 6a shows a further variant in connection with a
box;
Fig. 6b a perpendicular partial section of the box
along the line A - A of Fig. 6a;
Fig. 7 shows the tension element in accordance with
Fig. 6 in use with a round closure in its completely open
position;
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Figs. 8a to d show a structural drawing of the tension
element in accordance with Figs. 3a and b in detail, once in a
lateral view corresponding to the completely opened position of
the closure after manufacture, and
Fig. 8b the same tension element in its position when the
closure is completely opened,
Fig. 8c in the dead center position of the closure at
maximum stretch, and
Fig. 8d in the completely closed position.
The mode of operation of the closure in accordance with the
invention is illustrated in the schematic view in accordance with
Fig. 1. The lower part of the closure, which can be placed, for
example, on a container, is designated by 1. In~the closed ,.
position of the closure, the lower part 1 is covered by an upper
part 2...Tn.this way the upper part 2 forms a lid or cap on the
lower part 1. The two parts 1 and 2 are. connected in one piece
via a film hinge 3. The film hinge forms the axis of rotation in
relation to which the upper part 2 can be pivoted by approximately
180° in respect to the lower part 1. The film hinge 3 is
outwardly displaced in relation to the shell wall 6 of the lower
part 1 and to the shell wall 7 of the upper part 2 aligned with
it. To be able to produce the closure by injection molding in the
completely open state, the film hinge 3 must be located outside of
the said shell walls. A schematically shown tension element is
designated by the reference numeral 8. It has an upper attachment
point 4, by means of which the tension element 8 is fastened on
the upper part 2, and a lower attachment point 5, by means of
which the tension element 8 is fastened on the lower part 1..
Because the axis of rotation, formed by the film hinge 3, as well
as the upper attachment point 4 of the tension element 8 are
fixedly disposed on the closure, the upper attachment point 4
performs an excursion around the film hinge 3 on an arc of a
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CA 02080347 2000-04-25
circle with the radius r. However, the tension element 8 is
not fastened in the axis of rotation 3 but on the lower attach-
ment point 5 and therefore attempts to turn around this point.
If the tension element 8 could not be elongated, the upper
attachment point 4 has to move on an arc of a circle having a
radius P, where P corresponds to the length of the tension
element 8. The difference between these two radii r and P with
different axes of rotation inevitably results in a change in
the length of the tension element 8. This change in length is
shown in the drawings by ~P. This change in length generates
the force required for th~~ snap effect. How to design the
tension elements so that .such a change in length can be effec-
ted will be described below. Thus the force with which the
closure performs a anap effect depends on relatively simple
geometric considera~~ions. In contrast to the snap hinge
closures described :in the beginning, the hard-to-predict change
in the shape of the closure itself does not have any importance
in the mode of operation described above. The degree of elas-
ticity can be affeci:ed by the design of the tension elements.
Maximum change in length AP and the location of the dead center
position are essentially only dependent from the disposition of
the attachment points 4 and 5 in relation to the film hinge 3.
In this way the des_gner has a large degree of freedom in
respect to the design of a closure in accordance with the
invention. If, for examp7_e, in the variant illustrated the two
attachment points 4 and 5 are placed further inward while main-
taining the length c>f the tension element 8, the radius r is
increased by this and ~P, on the one hand, changes, as well as
the angular position of dead center, on the other. The optimi-
nation of the snap effect c:an be derived directly from the
drawing without experimentation. If the possible change in
length ~P is compar~~tive:ly great, the tolerance range regarding
the disposition of the attachment points of the tension element
is also great. This is in clear contrast to the
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plastic snap hinge closures known so far, which only permit a
small range of tolerance in respect to the geometric arrangement.
Figs. 2a and 2b each show a snap hinge closure in a
perspective view for the purpose of explaining the possible
disposition of the snap hinge. The variant according to Fig. 2a
shows a relatively narrow film hinge 3, via which the lower part 1
is hingedly connected with the upper part 2, and on both sides a
tension element 8, each disposed at the same distance from the
film hinge 3. In contrast thereto, the variant in accordance with
Fig. 2 shows two film hinges 3 at a certain distance from each
other and a centrally disposed tension element 8. In the
construction of non-cylindrical plastic closures it is possible to
realize different combinations of one or more film hinges with one .
or a plurality of tension elements.
Three variants of plastic snap hinge closures in accordance
with the embodiment of Fig. 2a are shown in Figs. 3a, b to 5a, b,
which only differ in the design of the tension elements 8:
If Figs. 3a, 4a, and 5a axe considered, which each show the
back view of a closed closure, it becomes clear that the
attachment points 4, 5 of each individual tension element 8 extend
parallel to each other when the closure is closed. However, in
Figs. 3b, 4b and 5b the hinge areas of the respective closures are
shown in the completely open position of the latter. In this
position each of the attachment points 4, 5 extends obliquely to
the other. In designing the tension elements 8 it is possible to
proceed in such a way that they are located straight in one plane
in the completely open position of the closure, as shown in Figs.
3b, 4b and 5b, but are completely relaxed. This would correspond
to the manufacturing position. With this disposition of the
tension elements, they would already be slightly stretched in the
closed position of the closure. Because of this the tension
elements exert a certain amount of closing force even in the
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closed position of the closure. an the one hand, this increases
the snap effect and, on the other, the closing movement is
maintained until the last in the course of the snap effect.
The attachment points of the tension elements are each
disposed at least approximately aligned with the shell walls in
the illustrated examples. However, this is not necessary. The
attachment points 4, 5 could also simply verge over into consoles
which are produced by injection molding~on the shell walls and
extend outward from them. This variant will be used particularly
if it is desired to dispose the tension elements 4, 5 on a round
closure relatively far from the main hinge 3. In this case a
variant is also conceivable where the attachment points of the
tension elements extend obliquely to each other. The disposition
of the tension elements in relation to the main hinge 3 as well as
the position of the attachment points 4, 5 in respect to each
other will have an effect on the choice of the shape of the
tension elements or their partial sections.
The embodiment in accordance with Figs. 3a and b shows
tension elements 8 consisting of three partial sections in the
shape of the lettex C. The three C-shaped partial section
constitute a meandering strap extending in a plane between the two
attachment points 4 and 5. The change in length of the tension
elements 8 is provided by spreading of the partial sections 10.
The more the tension elements 8 are stretched, the wider the C-
shaped partial sections 10 are spread. The direction of opening
of the G-shaped parts 10 alternates in this embodiment. But this
not an absolute. requirement.
Figs. 4a and b show a variant where the tension elements do
not consist of partial sections. While the partial section
adjoining the attachment points 4, 5 are semi-elliptical partial
sections 11, a completely elliptical partial section 12 is
disposed between them. It is of course also possible that a
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tension element a consists of three such elliptical C-shaped
partial sections. It is simply a question of definition, because
five C-shaped partial elements could also be recognized just as
easily in this shape. The more the tension elements 8 here are
changed in their length, the more the elliptical partial sections
are stretched into circular elements.
The embodiment in accordance with Figs. 5a and b shows
tension elements almost identical to those in Figs. 3a and b.
Only the partial sections 10 are disposed. differently.
Fig. 6 shows that the use of the snap hinge closure in
accordance with the invention is not limited to the employment of
round or otherwise shaped closures of containers. In this case
the snap hinge in accordance with the invention is fixed on a can
20. The lowerr can body 21 is connected with the can lid 22 via
the main,hinge 23. The two tension elements disposed on bath
sides of the main hinge 23 are identified by the numeral 28. Each
tension element 28 consists of four U-shaped partial elements 24.
In contrast to the embodiments of the tension elements described
so far, the partial sections 26 in this case do not extend within
the plane formed between the attachment points 24 and 25, but they
meander in an accordion-like manner out of the plane between the
two attachment points. In the example shown, the tension elements
consist of several U-shaped partial elements which adjoin each
other in such a way that they have an area which is rounded
towards the inside in respect to the closure and have a level area
towards the outside in respect to the closure. In this case the
level areas 30 are disposed in such a way that in the closed state
of the closure they are located in an aligned plane together with
the shell walls. However, the rounded areas 31 of the partial
sections 26 extend somewhat into the box in respect to the shell
wall. Such an embodiment of the tension elements is not only
suitable for boxes, but also for closures which axe fixed on a
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container. In this variant embodiment of the tension element,
too, the change in length is achieved by spreading of the U-shaped
partial elements 26. Although not required, the tension elements
can be formed by film hinges 32 in the area of the attachment
points 24, 25. This has the advantage that the tension elements
28 always extend nicely in the plane between the two attachment
points, regardless of the opening position of the closure or the
lid 22. This in particular simplifies the design of the injection
mold. If such a tension element 28 is attached to a round
closure, such as illustrated in Fig. 7, in the completely opened
state of the closure the partial sections 26 form a fan-shaped
strap which can be changed in length.
A tension element 8 in accordance with the embodiment of
Fig. 3a is shown in detail in Figs. 8a to 8d: Fig. 8a a is a
partial View of the closure in the area of the hinge. The
illustration corresponds to the position during injection molding,
where the closure is completely opened. Again the lower part 1 is
connected with the upper part 2 via a film hinge. In this case
the tension element 8 extends completely level and the attachment
points 4, 5 are disposed in recesses 14, 15 in the upper and lower
part. The same situation is shown in Fig. 8b in a view on the top
of the tension strap. The drawing plane is that plane which is
formed through the attachment points 4 and 5. If the distance
between the centers of the two attachment points 4 and 5, located
on the line B - B, is measured, it can be seen that in this
position the distance is shortest. In the real example, shown
here in a scale of 10:1, this distance a is 4.7 mm. However, in
Fig. 8c, in which the closure is shown in its dead center
position, the tension element 8 is changed to its greatest length,
i.e. the individual partial elements are spread the widest. In
this case the distance a has increased to 6.6 mm. This
corresponds to an increase of approximately 40%. In the closed
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position of the closure shown in Fig. 8d, the distance between the
two attachment points 4, 5 is still 5 mm. Accordingly, the
tension element 8 is still under stress even in the closed
position of the closure. In respect to the relaxed position in
accordance with Fig. 8a or Fig. 8b, the change in length still is
more than 6%. The maximum elastic change in length of the tension
elements will be advantageously selected to be between 10 and 50%.
But this depends to a large extent on the geometric conditions.
In addition to the percentage change of length, however, the
pulling force exerted by the tension element is of importance.
This is affected on the one hand by the geometric design of the
tension element and, on the other, by the material strength of the
partial sections. So that no deformation of the closure itself
occurs, it is practical to make the wall thickness of the partial
sections.co~siderably less than the wall thickness of the shell
walls in the area of the attachment points. If the percentage of
the maximum elastic change in length is chosen too small, the snap
effect only takes place in the range of dead center. As a lower
limit, a 10% change in length in the area of dead center would be
sensible.
As already shown by the few selected examples in accordance
with the attached drawings, the choice of the different variants
in the design of the closures in accordance with the invention is
almost unlimited. This is a very important advantage, especially
for plastic snap hinge closures. Almost every manufacturer of
cosmetic products, food or technical chemicals desires a special
design adapted to the packaging of his products. The designer now
actually has almost unlimited possibilities available with the
help of the instant hinge.
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