Note: Descriptions are shown in the official language in which they were submitted.
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Bottle Finish and Closure Cap with ~ouble Screw Thread
This invention concerns a container finish and a closure cap with a
twin-start thread.
Various closure arrangements with multi-start threads on the closure and
the container finish (neck portion) are state of the art. US 4,770,306, for
example, discloses a closure that possesses a twin-start thread. Each
thread extends over an angle of approximately 180°, and both threads
are
displaced so as to be diametrically opposite each other. An advantage of
such twin- or~multi-start threads is that the engagement between the
threads of the closure and of the neck of the container is greater when
compared with single-start threads. This enables the provision of shorter
threads, resulting in a considerably shorter opening or closing travel ~of the
closure.
In the case of containers that are filled with beverages
containing carbon dioxide, the internal pressure will be
raised when such a container is in the closed condition. On
opening the container, sudden ejection of the closure due to
the raised internal pressure should be avoided before the
internal pressure is reduced. Such ejection is accompanied by
a risk of injury to the consumer.
Also in the case of containers or closures provided with
means to vent the closure on unscrewing, there are certain
risks associated with misuse by the consumer. It is conceiva-
ble that, despite generally sufficient venting arrangements,
due to intentionally rapid unscrewing, closures of containers
containing carbon dioxide can be femoved so rapidly that
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venting time is too short: The high-speed ejection of closures in the
manner of a projectile cari be intentionally induced in this way.
US Patent No. 5,462,186 discloses a closure having two threads
which are circumferentially displaced at 180° with respect to each ,
other and having venting slots intersecting the threads. Each thread
extends over more than 360°, such that in circumferential direction
there are always at least two threads.
The purpose of the invention is to avoid the drawbacks of the
state of the art, and in particular to create a container
finish and a closure cap with a multi-start thread which
possesses improved venting properties for reduction of the
. , internal pressure during the opening sequence of containers
containing beverages with a carbon dioxide content.
A further purpose of the present invention is to create a
container finish and a closure cap which prevent the induc-
tion of excessively rapid unscrewing by the user, and ejec-
tion of the closure.
A further purpose of the present invention is to create a
closure and a container finish which can be economically
manufactured, in particular which require a small amount of
material and, when in the closed condition, are reliably
engaged with each other.
According to the invention, these purposes are fulfilled with
a closure and with a container finish according to the cha-
racterizing portion of. the independent patent claims.
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A container finish possesses in principle a cylindrical outer
surface on which two outwardly protruding threads are arran-
ged,, displaced by 180°. During opening, such an arrangement,
displaced by 180°, prevents tilting or one-sided opening of
the closure, and its ejection from the finish. The distribu-
tion of the force exerted from the container finish onto a
closure is, with such an arrangement, point-symmetrical and
diagonally opposed so that the risk of premature and one-
sided ejection is reduced.
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PCT/C897/00009
The threads are interrupted by venting recesses. During the
opening sequence, the venting recesses permit reduction of a
raised internal pressure within the container at a time when
a closure is still firmly engaged with the container finish.
Each thread preferably extends. over an angle of 240° to less
than 360°, preferably to 340°. The.selection of such an
angular range will, in combination with a suitable selection
of venting recesses, result in optimum venting behaviour, as
well as a secure interlock and force fit between the finish
and the closure.
The minimum thread length of 240° is required in order to
ensure a sufficient over-torque value.
Selection of an angle between 240° and 340° will result in
two first sections of the outside surface in which both
threads overlap vertically, and two second sections of the
outside surface, in each of which, vertically, only one
thread is arranged.
Good venting behaviour is attained if, in each first section,
at least one venting recess is arranged per thread, said
venting recess being aligned with the thread recess of the
other thread, and that at least one venting recess is arran-
ged in each second section. The alignment of the venting
recesses or "slots" preferably entails a vertical arrange-
ment. A lateral displacement of the superimposed "slots" is
possible as long as the free passage for exiting gas is not
essentially restricted.
In a particularly preferred embodiment, each such thread
extends through an angle of 280°. Preferably, exactly one
venting recess is used per section.
Apart from that, a particularly beneficial gas -release beha-
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' PC1'/CH97/OQ~009
viour will result from an irregular (not axially symmetrical
arrangement of the individual venting recesses.
The individual venting recesses are preferably formed to
taper inwardly. The opening angle amounts to between 40° and
70°, preferably between 55° and 65°, and each venting
recess
extends over an angular range of 4° to 10°, preferably ap-
proximately 5°.
An optimal pitch for the thread lies within the range 3° to
4°, preferably approximately 3.5°.
On its outside surface, beneath both the threads, the contai-
ner finish preferably possesses a retaining bead for holding
an anti-tamper strip of the closure. The selection of the
distance between the retaining element and the end of the
thread in relation to the axial extent of both threads is
significant for the opening behaviour. The distance between
the retaining bead and the thread end is selected to be les s
than 1.5 times and preferably equal to two-thirds of the
vertical extent of the section of the container finish provi-
ded with threads.~From the thread end to the end of the
closure cap, the gas seeks its way between the inside of the
closure and the outside of the container mouth.
The longer the distance between the container thread end and
the retaining element,.the longer the distance that must be
selected between the thread end of the closure and an anti-
tamper strip. The passage of the gas will be longer, and the
exiting gas will be subjected to greater resistance.
By selecting a greater distance, a worsened gas-release
behaviour will result.
A closure according to the invention essentially comprises a
base and a skirt surrounding said base, said skirt possessing
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PCT/C897/00009
an essentially cylindrical inside surface. On the inside
surface, two threads are arranged protruding radially inwards
and displaced by x.80°. In addition, venting recesses are
provided on the inside, said venting recesses interrupting
the threads.
Both threads preferably extend over an angle of 240° to less
than 360°, and preferably to 340°. By means of the diametri-
cally opposed arrangement of both threads, two first sections
of the inside surface will result in which both the threads
overlap vertically, and two second sections of the inside
surface, in each of which, vertically, only one thread is
arranged.
In each of the first sections, at least one venting arran-
gement is provided per thread, said venting arrangement being
aligned with the venting recess of the other thread. In each
second section, at least one venting recess is likewise
provided.
Preferably, each thread extends over an angle of approximate-
ly 280°.
In conjunction with a container finish described above,
particularly favourable opening behaviour for a closure will
result if, per thread, two venting recesses are arranged in
each first section and one venting recess in each first
section.
Apart from that, good gas-venting behaviour will also result
if the individual venting recesses are arranged irregularly,
e.g. not axially symmetrical.
The venting recesses preferably extend through an angular
range of 4° to 10°~, preferably 5°.
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Apart from that, in a particularly preferred embodiment, the
closure is provided with an anti-tamper strip. The anti-
tamper strip is connected with the lower edge of the circum-
ferential skirt of the closure by means of frangible bridges
or a frangible line. On its inside, the anti-tamper strip
possesses retaining means, said retaining means being able to
be brought into engagement with a retaining bead of a contai-
ner neck. Because two threads are used, their pitch can be
selected to be large in comparison to single-start threads,
without the engagement between the closure and a container
finish being too small. Thus, a pitch angle of 3° to 4°, for
example, can be selected, preferably 3.5°. Such a steep
thread pitch also means, however, that the forces exerted
onto the anti-tamper strip during the opening sequence will
take effect during a shorter time. By selecting such steep
threads, the dependability that an anti-tamper strip will
tear on initial opening of a closure is increased.
A combination of the container finish as described above with
the described closure is optimal. Both the closure threads
come into rapid engagement with the container finish threads.
Because two thread starts are arranged diametrically opposite
each other, when screwing on the closure a maximum of half a
turn must be made for the closure to come into engagement
with the container finish. In the case of single threads, in
the worst case a full rotation is required to attain this.
In a preferred embodiment, the closure and the container
finish engage with each other within an angular range of 300°
to 390°. This is possible due to the provision of two thre-
ads, even when each thread extends only over an angular range
of 240° to less than 360°. Preferably, a mutual engagement of
more than 360° is selected. By means of the specific arran-
gement of individual venting recesses, sequential and long-
duration venting is attained. Preferably, four venting reces-
ses are provided on the container finish, and six recesses on
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PCT/CH97/OA009
the closure. Each recess forms an uninterrupted path for gas.
If the recesses are asymmetrical and are not arranged at
regular angular spacing on the container edge and the closu-
re, during the unscrewing sequence, and thus during one
rotation (engagement 360°), there will be 24 constellations
where venting recesses on the closure coincide with venting
recesses on the finish. During the entire unscrewing sequen-
ce, therefore, venting will sequentially reach a maximum
value 24 times. In contrast, venting will occur at clearly
fewer separate points in time with closures possessing con-
ventional single threads and venting recesses.
To ensure good venting, at least one venting recess must be
provided in each of the second sections where, vertically,
only one thread is arranged. Because the exiting gas is
confronted with less resistance (only one instead of two
threads), it can flow out much more rapidly. For reasons of
safety, with single-start threads an arrangement where,
vertically, only one thread is arranged at one point is not
conceivable (insufficient mutual engagement).
Apart from that, it is advantageous to construct the closure
and the container in such a way that the distance between the
inner surface of the closure base and the side of the ends of
the thread turns oriented towards the closure base is selec-
ted to be greater than the distance between the edge of the
container mouth and the upper side of the thread start of the
threads on the container finish.
Tn a further preferred_embodiment, the thread start of the
threads on the container finish is not rounded but cut-off
vertically. In conjunction with a brake element on the ends
of the threads of the closure, a brake arrangement is thus
formed which exactly defines and limits the screw-on motion
of the closure.
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In accordance with one aspect of the present invention, there is provided a
container neck finish having a substantially cylindrical outside surface
defining
a longitudinal axis with two threads protruding radially outwardly, the
threads
being arranged on the outside surface so as to be displaced by 180°,
and with
the outside surface having two first sections and two second sections, and
venting recesses, the venting recesses interrupting the threads, the
improvement wherein each thread extends between an angle of 240° to
less
than 360°, wherein both the threads overlap each other in a direction
parallel
to the longitudinal axis in two first sections of the outside surface and
wherein,
in the direction parallel to the longitudinal axis, only one thread is
arranged in
each of two second sections, and wherein, per thread, at least one venting
recess is provided in each of the first sections, the venting recess being
located essentially in a direction parallel to the longitudinal axis aligned
with
the venting recess of the other thread, and wherein at least one venting
recess is provided in each of the second sections.
In accordance with another aspect of the present invention, there is provided
a closure having a closure base and a circumferential skirt affixed to the
base,
the skirt possessing a substantially cylindrical inside surface defining a
longitudinal axis with two threads protruding radially inwards, the threads
being arranged so as to be displaced by 180° on the inside surface, the
inside
surface having two first sections, and having venting recesses interrupting
the
threads, the improvement wherein each thread extends between an angle of
240° to less than 360°, both the threads overlapping each other
in a direction
parallel to the longitudinal axis in the first two sections of the inside
surface
and wherein, in the direction parallel to the longitudinal axis in each case
only
one thread is arranged in two second sections, and wherein, in each of the
first sections, at least one venting recess is provided per thread, the
venting
recess being aligned essentially in a direction parallel to the longitudinal
axis
with the venting recess of the other thread and wherein, in each second
section, at least one venting recess is provided.
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In accordance with a further aspect of the present invention, there is
provided
a closure arrangement comprising a container neck finish and a closure cap
for closing the container, the cap having a cap base, the container neck
finish
having a substantially cylindrical outside surface defining a longitudinal
axis
with two threads protruding radially outwardly, the threads being arranged so
as to be displaced by 180° on the outside surface, the outside surface
having
two first sections and two second sections, venting recesses interrupting the
threads, and wherein the closure possesses a closure base and attached to
the base a circumferential skirt with a substantially cylindrical inside
surtace,
the inside surface having two first sections and two second sections, two
radially inwardly protruding threads, displaced by 180° being arranged
on the
inside surface, as well as venting recesses which interrupt the threads,
wherein threads of the closure are capable of being brought into engagement
with threads of the container neck finish, wherein each thread of the
container neck finish and each thread of the closure extends at an angle of
between 240° to less than 3fi0°, and wherein, in the two first
sections of the
outside surface of the container neck fnish, both the threads of the container
neck finish overlap each other in a direction parallel to the longitudinal
axis,
and wherein in the direction parallel to the longitudinal axis, in each case
only
one thread is arranged in two second sections of the outside surface of the
container neck finish, and wherein both the threads of the closure overlap
each other in the direction parallel to the longitudinal axis in the two first
sections of the inside surface, and wherein, in the direction parallel to the
longitudinal axis in each case only one thread is arranged in the two second
sections of the inside surface, and wherein, in each of the first sections of
the
outside surface of the cantainer neck finish, per thread, at least one venting
recess is provided, the venting recess being aligned in the direction parallel
to
the longitudinal axis with the venting recess of the other thread, as well as
at
least one venting recess in each of the second sections of the outside
surface, and wherein at least one venting recess is provided per thread in
each of the first sections of the inside surface of the closure, the venting
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recess being aligned essentially in the direction parallel to the longitudinal
axis
with the venting recess of the other thread, as well as at least one venting
recess in each of the second sections of the outside surface.
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In a further preferred embodiment, the container finish
and/or the closure cap are provided with additional means to
brake the screw-off motion. Not only the container finish but
also the closure cap can be provided with independently
functioning means. It is also conceivable, however, to provi-
de the container finish and the closure with mutually enga-
ging means. As soon as the venting function occurs, the
unscrewing motion of the closure is subjected to braking.
Accordingly, there will be a greater period of time for
venting. This prevents ejection of the closure, also with
inappropriate handling (too rapid opening).
It is particularly simple to provide the container finish
with at least one mechanical stop arranged between the thre-
ads, said mechanical stop being able to be brought into
engagement with elements of a closure when the internal
pressure is high. If the closure is raised axially when the
internal pressure is high, elements of the closure engage
with the mechanical stop on the container mouth and prevent a
further unscrewing motion. As soon as the internal pressure
in the container has been reduced by venting, the closure can
be pressed downwards in an axial direction, by which means
the elements of the closure disengage with the mechanical
stop. The elements of the closure engaging with the mechani-
cal stop on the container mouth can, for example, be inter-
ruptions of the threads, i.e. venting recesses.
A similar arrangement of mechanical stops can naturally also
be attached to the inside of the closure cap. With that,
mechanical stops are attached to the side of the threads
oriented towards the cap base, said mechanical stops being
able to engage with elements of the container mouth, in
particular the threads on the container mouth, when the
closure cap is lifted up by internal pressure.
It is also conceivable to provide braking elements which do
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PCT/CH97/00009
not interrupt the unscrewing motion but apply a gradual
braking effect. This uniform braking effect is practical for
the user because it is less evident and requires no additio-
nal motion such as axially downward pressing of the closure.
In a particularly simple embodiment, for continuous braking,
protrusions can be provided on the inside surface of the
skirt. These protrusions extend in a radial direction ap-
proximately far enough inwardly so that they make dragging
contact with the maximum outside diameter of the container
mouth, e.g. engage with the outside diameter of the thread.
These protrusions can, for example, be arranged towards the
lower edge of the skirt so that they first engage with the
threads after a certain unscrewing motion and create a bra-
king effect. The closure cap can thus be rotated off in an
initial opening step without being subjected to braking. Only
in a second step, during which the closure vents, will the
braking elements become active.
Apart from that, in a particularly advantageous embodiment,
in the axial direction toward the cap base the protrusions
are reducing radially in thickness. This leads to a constant-
ly rising braking force toward completion of the unscrewing
motion.
Similar advantages can also be aimed at with a protrusion
that in principle extends over the entire height of the
threads and preferably ends adjacent to the lower edge of the
skirt.
In a further embodiment, the inside surface of the cap skirt
is provided with bridge-like protrusions between the threads,
said bridge-like protrusions creating the braking effect.
Naturally, the braking elements portrayed for a closure can
in each case also be applied to a container mouth to similar
effect. Corresponding to their alternative action, in the
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case of protrusions on the container at most said protrusions
must be positioned and formed slightly differently. Particu-
larly in the case of protrusions with a thickness changing in
the axial direction, said protrusions are preferably arranged
adjacent to the edge of the mouth and possess a thickness
that reduces in the axial direction towards the container
edge.
The illustrated devices for braking the unscrewing motion
also possess great advantages in relation to threads that are
not twin-start threads. with any thread design for ventable
closures, it can be advantageous to brake the unscrewing
motion with such elements.
The invention is more closely explained on the basis of
following drawings and embodiments; namely,
Figure 1 a three-dimensional view of a container finish
according to the invention;
Figure 2 a three-dimensional representation of the threads
of a closure according to the invention, with a
closure skirt depicted by dotted lines;
Figure 3 a three-dimensional sectional drawing of a combi-
nation according to the invention of a closure
and a container finish;
Figure 4 a side view of the container finish according to
figure 1;
Figure 5 a developed side view of the inside of the closu-
re according to figure 2;
Figure 6 a developed view of the outside surface of the
container finish according to figure 1;
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PCT/CFi97/00009
Figure 7 a cross section through the closure according to
figure 2;
Figure 8
and 9 developed views of alternative embodiments of a
closure and a container finish;
Figure 10
and 11 developed views of the inside of a closure with
means for braking the unscrewing motion;
Figure 12 a developed view of the outside surface of a
container finish with means for braking the uns-
crewing motion of a closure;
Figure 13 a developed view of the inside surface of a clo-
sure with an alternative embodiment of means for
braking the unscrewing motion;
Figure 14 a cross section through a closure according to
the developed view from figure 13;
Figures 15a
and 15b the developed view from figure 10 of a container
mouth in two stages of an opening sequence, with
threads depicted by dotted lines; and
Figures 16a
and 16b a cross section of a closure cap according to
figure 14, fitted to a container, during two
stages of an opening sequence.
Figure 1 shows a container finish 1 possessing the features
of the invention.
The finish 1 of a container la (not shown in greater detail
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PCT/CH97/00009
here) possesses an outside surface 2 upon which two threads 3
are arranged. Both the threads 3 are arranged so as to be
displaced by 180°, and each extend over more than 280°. In
this way, two first sections 5 are formed in which the thre-
ads 3 overlap vertically. In contrast, only one thread 3 is
arranged in two second sections 6. To enable a rapid reduc-
tion of pressure when removing a closure from the container
finish 1, the threads 3 are interrupted by venting recesses
4. Per thread 3, one venting recess 4 is accommodated in each
of the sections 5 or 6. In the sections 5 in which both the
threads 3 overlap, the recesses are aligned vertically one
above another. Apart from that, the container finish 1 pos-
sesses a retaining bead 7 which can be brought into engage-
ment with the anti-tamper strip of a closure.
Figure 2 shows the thread run of a closure 11 possessing the
features of the invention. The closure possesses a base 20
and a cirumferential skirt 21 attached to said base. Two
radially inwardly protruding threads 13 are arranged on the
inside 12 of the circumferential skirt 21. Both threads 13
are attached to the inside surface 12, displaced at 180° to
one another. Each thread 13 extends through an angle of 280°
so that initial or first sections 15 are formed in which two
threads 13 lie vertically above one another, as well as
second sections 16 in which, vertically, there is only one
thread 13. In each of these sections 15, 16, each thread is
interrupted at one point by a venting recess 14. In the first
sections 15, in which both the threads overlap vertically,
the venting recesses 14 on the individual threads 13 are
mutually aligned. In this way, a recess crossing both threads
will arise. An anti-tamper strip 17 is connected to the lower
edge of the circumferential skirt 21 by means of frangible
bridges 22.
Figure 3 shows the combination of a closure 11 with a contai-
ner finish 1 possessing the features of the invention. A
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PCT/CHI97/00009
portion of the closure skirt and container finish are shown
so as to form a partial cross section. The threads 3 of the
container finish I engage with the threads 13 of the closure
11. The anti-tamper strip 17 of the closure 11 is held firmly
on the retaining bead 7 of the container finish 1 by means of
retaining elements 18.
Figure 4 shows a side view of the container finish 1 shown in
figure 1. Both threads 3 are arranged with a pitch a, wherein
a preferably amounts to 3.5°. Both the threads 3 are inter-
rupted by venting recesses 4 and end towards the container
mouth in a thread start 9. The thread start 9 possesses a
clearly cut edge 24 to form a limit to the screw-on motion. A
distance d2~is formed between the upper side of the thread
start 9 and the edge of the container 10. A second distance d
is formed between the lower side of the thread end 8 and the
upper side of the retaining bead 7. The distance d amounts
approximately to two thirds of the vertical extent v o~ the
section of the container finish 1 provided with threads.
Figures 5 and 6 show developed views of the inside surface 12
of the closure 11 (figure 5) and the outside surface 2 of the
container finish 1 (Figure 6). On the inside surface 12 of
the closure 11 there are, in each case, two sections 15 in
which the threads 13 overlap vertically and two sections 16
in which, vertically, only one thread ~13 is arranged. One
venting recess 14 is provided in the sections 15, said recess
interrupting the thread. l3. In the sections 15, in each case
two venting recesses 14 are provided per thread 13. The
venting recesses 14 in the sections 15 are arranged in such a
way that two recesses are created passing completely through
both threads 13. The individual venting recesses 14 are
arranged circumferentially with different intermediate spa-
ces. For improvement of the gas venting behaviour, the inside
surface 12 can additionally be provided with small depres-
sions running transversely across the skirt 21 in the area tit
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PCT/CH97/00009
the recesses 14.
Figure 6 shows the developed view of a container finish 1 to
fit the closure according to figure 5. First sections 5 are
formed where both the threads 13 overlap vertically. Second
sections are defined where, vertically, only one thread 3 is
arranged. In each of the sections 5 or 6 one venting recess 4
is provided per thread.3, said venting recesses interrupting
the threads 3. In the sections 5, the venting recesses 4 of
both threads 3 are aligned in such a way that an uninter-
rupted path for gas is formed. The individual venting reces-
ses 4 are not regularly positioned around the circumference,
and do not coincide with the venting recesses 14 of the
closure ll.~With a rotation of 360° during removal of the
closure 11 from the container finish l, there will be 24
constellations where the gas contained in the container can
escape through superimposed venting recesses 4 and 14.
Figure ? shows a cross section through a closure according to
figure 2. The closure preferably possesses a sealing means 2.3
which can be brought into engagement with the upper edge of a
container finish: Retaining elements 18 are provided on the
anti-tamper strip 17, said retaining elements being able to
be brought into engagement with a retaining bead of a contai-
ner finish. A distance dl is defined between the upper side
of the thread end 19 and the inner surface of the closure
base. If the distance dl is selected to be greater than the
distance d2 from figure 4, an engagement of more than 280°
can be selected with a combination of closure 11 and contai-
ner finish 1, even when each of the threads 3, 7.3 only extend
over an angle of 280°. Preferably, the relationship dl to d2
is selected in such a way that the closure I1 engages with
the container finish 1 over an~angular range of 360°. The
threads are arranged with an angle ~i of approximately 3.5°.
Figure 8 shows the developed view of the inside surface 12 of
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PCT1CN97100009
an alternative embodiment o.f a closure 11. Two venting reces-
ses 14 are provided in'each of the sections 16 in which,
' vertically, only one thread 13 is arranged. Accordingly, two
additional venting constellations will arise during the
opening sequence, and thus a still more regular gas venting
behaviour. The recesses 14 in the sections 15 are mutually
aligned in a line that is gently inclined in relation to the
vertical.
Figure 9 shows the outside surfaces 2 of an alternative
embodiment of a container finish 1. Each thread 3 is inter-
rupted by two venting recesses in each of the sections 5, 6.
The venting. recesses 4 in the sections 5 align in a line that
is slightly inclined in relation to the vertical.
Figure 10 shows the developed view of the inside surface 12
of a closure 11 which is additionally provided with means to
brake the unscrewing movement of the closure. A protrusion 25
forms a mechanical stop surface which can come into engage-
ment with elements of the container finish and so momentarily
interrupt the unscrewing motion. With high internal pressure
in the container; the closure 11 is pressed upwards in the
axial direction. If the closure is in position on a container
with venting recesses,.with appropriate dimensioning the
protrusions 25 will snap into the venting recesses on the
container finish. Naturally, other form features can be
provided as a counterpart to the protrusion 25. Due to the
coordinated connection between the protrusions 25 and the
container mouth, the closure cannot be subjected to further
rotation before the internal pressure of the container has
reduced, permitting the closure to be pressed axially down-
wards. By means of an axially downward motion, the protrusion
25 will become disengaged from the container finish, and the
closure can be subjected to further unscrewing.
Figure 11 shows a closure 11 which, on its inside, is provi--
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PCT/CH9T/00009
ded with bridges 26 between the threads 13. The bridges 26
are dimensioned in such a way that they define a free inside
diameter that is approximately the same size or slightly
smaller than the maximum outside diameter of the threads of
the container to be closed. As~a result, the threads of a
container rest upon the bridges 26 between the threads 13 of
a closure 11 and create a dragging effect which leads to
braked unscrewing of the closure. Depending on the dimensio-
ning of the bridges 26, a greater or lesser braking effect
can be defined at different phases of the unscrewing motion.
As long as the threads of a container finish rest upon all
the bridges 26, the closure will be subjected t.o uniform
braking in the unscrewing motion.
Figure 12 shows the developed view of a container finish 11
which is provided on its outside surface with threads 12. A
protrusion 27 is provided between the threads 3, said protru-
sion forming a mechanical stop for features of a closure. If
a closure is pressed axially upwards due to the pressure
prevailing in the container, it will run up against the
protrusion 27 during the unscrewing sequence, wherein the
unscrewing motion will be interrupted. As soon as the gas
pressure within the container is reduced, the c7_osure can be
pressed downwards, and enables a continuation of the uns-
crewing sequence. .
Figures 13 and 14 show an embodiment of a closure which is
provided on its inside with two different protrusions for
uniform braking of the unscrewing motion. Ribs 29 are provi-
ded on the lower edge of the closure skirt, said ribs drag-
ging against the outside diameter of a container mouth and
thus creating a braking effect. Apart from that, protrusions
28 are provided in the area of the threads, said protrusions
likewise creating a uniform braking effect of the unscrewing
sequence. Naturally, the protrusions 28 and the ribs 29 also
function independently.
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The protrusions 28 and the ribs 29 are formed in such a way
that there is no abrupt stop to the unscrewing motion, but
rather a continuous braking action. In particular, the thick-
ness of the protrusions 28 and the ribs 29 is formed to
increase in the axial direction towards the lower end of the
closure cap. The protrusions 28 and the ribs 29 extend from
the inside surface of the closure cap. With such a design, a
braking effect is attained that is almost zero at commence-
ment of the unscrewing motion. By means of continued uns-
crewing of the closure, the free inside diameter of the
contact surface of the protrusions 28 or the ribs 29, said
contact surface dragging against the outside surface of the
container finish, will become increasingly small. This leads
to a greater pressing force of the protrusions 28 or ribs 29
on the outside surface of the container mouth, and thus to
increased frictional force and braking effect.
Figure 15a shows the developed view of the inside surface 12
of a closure 11, said surface being provided with a protru-
sion 25, said protrusion forming a mechanical stop (also see
figure 10). A complementary thread 30 on a bottle mouth is
depicted by a dotted line. The thread 30 possesses inter-
ruptions 31 (venting recesses). In figure 15a, the closure 11
is in a position on the container mouth where the venting
function has not yet properly begun. By means of the pressure
prevailing in the container, the closure cap 11 with its
thread 13 is pressed upwards towards the thread 30 of the
container mouth.
Figure 15b shows the same section of the developed view of an
inside wall 12 of a closure cap 11 which, compared with
figure 15a, is slightly rotated, e.g. opened. With that, the
protrusion 25 on the upper side of the thread 13 of the
closure cap 11 is engaged with the threads in the venting
recess 31, said venting recess 31 being between two portions
of the thread 30 on the container mouth. By means of the
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- overpressure prevailing in the inside of the container, the
closure cap is pressed upwards in the axial direction (arrow
A). Accordingly, the protrusion 25 will come into engagement
with the venting recess 31, e.g. with the start of a segment
of the thread 30. This engagement remains for as long assn
overpressure prevails inside the container. During this, time,
the overpressure can be reduced thanks to the venting reces-
ses in the closure cap and on the container mouth. Only when
the pressure on the inside,of the container has sunk below a
specific reference value can the closure cap 11. be pressed
downwards again (in the opposite direction to arrow A), the
mechanical stop becoming disengaged with the venting recesses
31. After pressing down the closure cap 11, the unscrewing
motion can be continued. Naturally, it is conceivable to form
a container mouth in such a way that the mechanical stop 25
engages not with the recesses 31 but with counter stops
specially formed for this purpose.
The advantage of this arrangement is that the closure cap
only be completely removed from the container when the pres-
sure in the inside of the closed container has been complete-
ly or almost completely reduced.
Figures l6a and 16b schematically show two stages of the
unscrewing sequence of a closure, as has been shown in figure
14. The closure 11 is screwed onto a container mouth and is,
with its threads 13, engaged in the counter thread 30 of said
container mouth. A protrusion 28 extends from the inside
surface of the closure cap 11, so that its surface makes
contact with the surface of the counter thread 30 on the container
mouth. As can be seen in figure 16a, the pressing effect of
the protrusion 28 is still slight when the closure is com-
pletely fitted. At the point where the protrusion 28 posses-
ses the greatest thickness, there is still no contact with
the thread 30 of the container mouth. Only during the uns-
crewing sequence (see figure 16b) does the protrusion 28, due
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to its increasing thickness, increasingly engage with the
thread 30 of the container mouth. Due to the increasing
thickness, the pressing force of the protrusion 28 on the
thread 30 increases, by which means the unscrewing motion of
the closure cap is braked. It is important that the venting
function commences before widening of the outside by the
protrusion (or protrusions) becomes too great. With the
protrusions 28, the unscrewing.motion is indeed subjected to
braking, but the engagement between container mouth and
closure cap also becomes less (due to expansion of the cap
wall). It is therefore important that the inside pressure in
the container is reduced before the protrusion 28 has reached
its full effect.
Inasmuch as the invention is subject to modifications and
variations, the foregoing description and accompanying dra-
wings should not be regarded as limiting the invention, which
is defined by the following claims and various combinations
thereof
