Note: Descriptions are shown in the official language in which they were submitted.
CA 02037496 1999-12-07
Plastic Snap Binge With A Flexible Element
Generating The Snap Action
This invention relates to a single piece plastic
closure with a snap hinge having two parts connected by at
least one hinge, and a flexible element generating the snap
action, which is hingedl.y connected to the two parts of the
closure.
Plastic snap hinges for closures can be roughly
classified into two types, namely those where the snap
effect is generated by a. tension element and those where it
is generated by an elastically flexible element. This
invention relates to a closure with a plastic snap hinge of
the second type.
Conventional elastically flexible elements have a
shape in the form of a letter "U" or "L", as, for example,
is known from U.S. Pat. No. 4,911,324 or U.S. Pat. No.
2,630,239. The size of the elements is essentially
determined by the spring path and the desired spring force.
However, particularly .in connection with the use of plastic
tops, other marginal conditions which greatly affect the
geometry of a plastic snap hinge are opposed to this.
Conventional flexible elements cannot be used, particularly
when employing tops with relatively large pouring spouts
and a relatively f:Lat lid. In the case of an L-shaped
flexible element, -the leg extending through the cover of
the lid cannot be made sufficiently long, because otherwise
it would extend in~~o the sealing area of the pouring spout.
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A U-shaped flexib:Le element cannot be made sufficiently
large, because the low :height of the lid does not provide
enough space to accept the flexible element.
Such a hinge has its most relaxed position when the
corrugated hinge strips are at least curved. This
condition occurs in a position between opened and closed.
Another solution is taught by U.S. Pat. No. 3,629,901
where the elastically f:Lexible element is parted in two
sections of U-shape form as corrugated hinge strips, while
an intermediate inflexible section remains.
It is one object of this invention to provide a
flexible element which can be used in connection with
plastic hinges which is fully integrated into the form of a
single piece plastic closure having a flat top cover part
and a lower part with a circumferential wall being vertical
to the flat top cover in the area of the hinge.
Accordingly, the present invention relates to a
single-piece plastic snap-hinge closure comprising a lower
part, a cap, and a flexible element. The lower part forms
a pouring spout opening and has a circumferential wall.
The cap comprises a flat top surface part. The lower part
and the cap are connected to each other by film hinge means
defining a pivoting axis of the closure. The film hinge
means is situated on a line defined by an intersection of
an outer surface of the circumferential wall and the flat
top surface part of the cap when the closure is in a closed
position. The fle:Kible element generates a snap action.
The flexible element is connected to the lower part by a
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first flexible element film hinge integral with the outer
surface of the circumfe:rential wall, and connected to the
cap by a second flexible element film hinge integral with
the flat top surface part of the cap. The flexible element
comprises a plurality of partial sections forming a shape
of an "S". The "S"-shaped flexible element having two
outermost legs equal in size to each other and
interconnected by a central portion. The legs of the "S"-
shaped flexible element are one of perpendicular and
parallel to the outer surface of the circumferential wall
in an open position of t:he closure and are the other of
perpendicular and parallel to the outer surface of the
circumferential wall in the closed position of the closure.
The flexible element in the open position of the closure is
disposed as much outside a shape defined by the
circumferential wall and. the flat top surface of the cap as
it is inside the shape in the closed position of the
closure.
A significant benefit of the hinge construction in
accordance with this invention is that it provides better
flexibility than known hinge constructions thus permitting
closures with thinner walls to save plastic material and
reduce costs.
Further embodiments in accordance with the invention
and their purpose will be explained in the description
below.
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Two preferred embodiments of this invention are
illustrated in the drawings and will be explained in the
following description, wherein:
FIG. 1 is a perspective view of a plastic top and the
snap hinge in accordance with one embodiment of this
invention;
FIG. 2 is a longitudinal section of the flexible
element of the top, as shown in FIG. 1, in a closed
position;
FIG. 3 is a view of= the flexible element shown in FIG.
2, in a half-opened position;
FIG. 4 is a view of the flexible element shown in FIG.
2, in a fully open position;
FIG. 5 is a cross-sectional view, crosswise to the
previously illustrated sectional planes of the top in
accordance with FIG. 1, placed on a container;
FIG. 6 is a cross-sectional view, of another
embodiment of the :plastic top with a differently positioned
flexible element, in a closed position; and
FIG. 7 is a cross-sectional view in accordance with
FIG. 6, with the f:Lexible element in a completely open
position.
A plastic top is shown in FIGS. 1 to 5, which is
suitable for use with a plastic container 30 having only a
small pouring spout. 31. Such containers are particularly
used in connection with cosmetics which are applied
directly to the skin, such as suntan lotions or body
lotions. This requires that a cap 2 of the top can be
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rotated about at :Least 180°, with respect to a closed
position of the top.
The top comprises a lower part 1 and the cap 2, which
are pivotally connected with each other with two film
hinges 3 positioned in a straight line. A flexible element
4 is positioned between the two film hinges 3 and generates
a spring force nec:essar:y for the snap action.
The lower pant 1 comprises an annular, circumferential
wall 10 having a c:onica:Lly tapering collar 11. The pouring
spout 31 of the containE~r 30 is disposed within the lower
part 1 of the clo:>ure. A gap 12 remains between the cap 2
and the lower part: 1, even in the closed position. This is
required so as to make it possible to injection-mold the
top in the closed position. The collar 11 of the lower
part 1 is depressed in an area opposite the film hinge 3 to
form a recess 13 which makes it possible to push the cap 2
upwards with a thumb, beyond the unstable equilibrium
position, after which the cap snaps into a completely
opened position, as shown in FIG. 4.
Sealing the cap 2 with the pouring spout 31 of the
container 30 is accomplished with a sealing tang 21,
injection-molded to the underside of the cover 20. To
enhance the seal and i:n particular the closing strength,
the tang 21 may have at least one circular seal ring 22.
For reasons of appearance as well as for increasing the
stiffness, the cover 20 in accordance with this embodiment
of the invention is formed upwardly concave in this case.
A plurality of support cams 23 may be provided on the
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underside of the cover 20, for defining the relative
position of the cap 2 with respect to the container 30. In
the assembled stage of 'the top and closed position of the
cap 2, the support: tangs 23 rest on the container 30.
In this embodiment, the flexible element 4 can also be
ejected from a mo:_d in the closed position of the top. In
cross section, the flexible element 4 has the shape of the
letter "U" and of a fal:Lowing, upside-down letter "L". The
opening 40 of the U-shaped part extends exactly in the
extraction direction of the mold tool. The flexible
element 4 is connected with the cap 2 and the lower part 1
with two flexible element hinges 41 and 42 integral with
circumferential wall 10 of lower part 1 and the flat top of
cap 2. The hinge 41 forms the connection between the
circumferential well 10 and the flexible element 4 and is
located approximately at: the level of the upper edge of the
container 30, on ~rhich t:he top has been mounted.
The hinge 42 connects the cap 2 to the flexible
element 4. As shown mo~~t distinctly in FIG. 4, the two
flexible element hinges 41 and 42 are at the same distance
from the fixed film hinge 3. In such arrangement, the
minimal distance between the two flexible element hinges 41
and 42 is a~~, if the distance from each hinge 41, 42 to
the film hinge 3 is equal to "a". In the unstable
equilibrium position, such as shown in FIG. 3, the maximum
distance between the two hinges 41 and 42 is attained and
is exactly 2~a. This is. the case when the two hinges 41,
42 are located vertically on top of each other.
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A further embodiment of the invention is shown in
FIGS. 6 and 7, and has .a second top. It essentially has
the same characteristics as the previously described top
illustrated in FIGS. l.to 5. However, the top of FIGS. 6
and 7 is suited for use with a container 30', shown in
dashed lines, with a container neck 32. Accordingly, the
lower part 1 must be designed in such a way that it can
enclose the contaner neck 32. For this purpose, the side
wall 10 of the lower part 1 abutting against the container
30' has a cover 14 with a vertically downward directed
annular wall 15, which surrounds and seals the container
neck 32 of the container 30'. A spout 16 has been formed
in the cover 14 of the :Lower part 1 within the area defined
by the annular waJ_1 15. It is closed by a tang 21 formed
on the cover 20 of. the cap 2. In this case, the seal is
not made between t:he container and the cap 2 but, as is
customary with plastic i:ops, between the lower part 1 and
the cap 2. Of course, l.he cover 14 of the lower part 1
does not permit a unifiE~d manufacture of the top. It is
injection-molded i.n the completely open position, as shown
in FIG. 7. This i.s pos;~ible because the flexible element 4
can be positioned in such a way that it can be ejected from
a mold even in they completely open position of the top.
The opening 40, visible from the outside in the closed
position of the top, is now located in the side wall 10 of
the lower part 1. However, in the completely open position
of the top the flexible element 4 is flipped outward by 90°
around the hinge 91. Now the opening 40 extends vertically
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downward and thus parallel to the side wall 10 and in the
extraction direct_Lon of the injection mold.
In this embodiment, too, the same geometry of the
flexible element has been used, as the embodiment shown in
FIGS. 1 to 5. Although only one general shape, and most
likely the one used mast often, has been illustrated, such
important aspect of this invention can be expressed more
generally, and it is of course obvious, that the partial
sections of the flexible element 4 need not necessarily
extend parallel. Thus, instead of a U-shaped part there
can be a V-shaped part. Also, the partial sections which
in this case are ~>traight, can be arched. In principle, it
is only necessary that l.he flexible element 4 be designed
accordion-like, so that it is always possible to extend a
straight section which penetrates the flexible element at
three different points. Only those flexible elements which
meet this geometric definition provides an accordion-like
shape, which allows great expansion in a small space and
provides a large force f=or the snap effect.
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