EP0370272B1 - Screw closure for bottles having a deaeration device - Google Patents

Description

The present invention relates to a screw cap made of plastic for pressurized bottles for carbonated drinks according to the first part of claims 1 and 8, respectively. Such a cap is known from EP-A-0055916. A constriction is formed between the projecting edge of the bead and the upper outer edge of the mouth of the bottle, so that an intermediate sealing washer is pressed particularly firmly in this area with a high specific surface pressure and thus closes the bottle pressure-tight. For this reason, bottles with carbonated drinks in particular are provided with such screw caps.

A disadvantage of these pressure-tight screw caps, however, lies in the fact that the bottle can explode in cases where excessive pressure builds up inside the bottle. Such cases have become known several times in the past, with considerable injuries caused by exploding bottles.

The present invention is therefore based on the object of redesigning the closure known from EP-A-0055916 in such a way that it is still pressure-tight for the usual uses, but the maximum pressure up to which the closure remains tight is limited to a value that is significantly below the pressure at which a Bottle explodes.

This object is achieved with the means specified in claims 1 and 8, respectively.

The bead, which rotates in the manner of a circular ring in the corner formed between the cap base and cap shell, does not therefore extend over the entire inner circumference of the cap base or cap shell, but is over a certain angular range, i. H. interrupted or omitted in a segment of the ring. The high contact pressure along the opposite edge lines of the bead and the closure edge of the bottle is then missing in this segment.

The sealing washers used have sufficient rigidity so that they still lie pressure-tight on the edge of the closure edge of the bottle even over the interruption segment. If, however, the pressure in the bottle becomes too great, the sealing disc yields in the area of this segment and presses into the area of the transition between the cap base and the cap jacket, in which the said bead is otherwise arranged in the area of the remaining circumference. An overpressure can escape between the sealing washer and the closure edge of the bottle, this being additionally facilitated by the fact that in the preferred embodiment of the invention the thread of the closure has ventilation channels running transversely to the threads. Likewise, the thread on the closure edge of the bottle can have ventilation channels running transversely to the thread.

In practice, it has been found that the segment-like interruption of the bead should extend over an angular range of at least 15 ° for the desired function of the new screw closure in the sealing disks that are usually used.

On the other hand, it should also extend over an angular range that is less than 60 °, otherwise the Tightness of the closure cannot be ensured under normal conditions.

Embodiments of the screw closure are preferred in which the segment-like interruption extends over an angle of 30 ° or 45 °, the choice also depending on the type of sealing washer used and the desired maximum pressure. If the sealing washer is relatively thin and at the same time very flexible and elastic, the bead will usually only be interrupted over a smaller angular range, which may even fall below the stated value of 15 ° in the case of very thin and very elastic sealing washers.

Regardless of the specifically selected angular range, several such interruptions can optionally be provided along the circumference of the bead. From the point of view of proper functioning, it appears most sensible if the interruption segments each extend over the same angular ranges and are also spaced apart from one another by the same angle.

However, the effect of the new closure can also be achieved in other ways, even if the bead is not interrupted. Instead of a recess in the bead, it is proposed to solve the problem in such a case that the sealing disk has at least one recess on its upper side facing the cap bottom in its area of contact with the mouth edge of the bottle. When the closure is screwed on in a pressure-tight manner, the sealing disc is in its outer region between the closure edge of the bottle and the bead compressed. If the sealing washer has a recess or depression on its upper side, which faces the cap base, it is not or less compressed in this area, in which it is thinner than in the rest of the sealing area because of this recess, so that here too correspondingly high pressure in the bottle, the sealing disc is lifted in the region of the recess from the mouth of the bottle, so that the pressure can escape. In this case, too, additional ventilation channels can be provided in the thread area.

The application of a recess on the top of the sealing washer, in a manner similar to the segment-like interruption of the bead on a pressure-tight closure, causes a weak point to be created in the pressure-tight connection between the closure and the bottle, through which excess pressure can escape.

The sealing washer must of course not be designed as a full circular disk, but it would be sufficient in any case if a seal, for. B. in the form of a circular ring in the region of the closure edge of the bottle in the cap.

The angular range along which a recess is to extend in the surface of the sealing washer is somewhat smaller than the angular range provided for the segment-like interruptions of a bead, but should be at least 10 ° according to practical experience. In the preferred embodiment, such a recess extends in the region of the outer edge of the sealing washer over an angular range of 15 to 35 °.

It appears to be advantageous for the function of the closure if the depth of the recess corresponds to at least half the thickness of the sealing washer. The sealing washer is in the case of a more or less line-like contact pressure such. B. often when using the bead described above significantly less than half of their other thickness compressed, so that even if the sealing washer in the area of the recess is only half as thick as in the rest of the area or even thinner, there is still sufficient contact pressure for a seal against a low and tolerable excess pressure consists. At the same time, however, the sealing washer can yield in this thinner area if the pressure in the bottle increases noticeably.

An embodiment of the closure is also expedient in which a plurality of recesses are provided along the circumferential region of a sealing washer, and it may be advantageous if these recesses are of the same type, ie. H. have the same depth and extend over the same angular ranges and are also arranged at the same angular distances relative to one another.

Further advantages and possible uses of the present invention will become clear from the description of a preferred embodiment and the associated figures.

Figur 1

einen Querschnitt durch einen Verschluß mit Wulst und Unterbrechungssegment,

Figur 2

eine Figur 1 entsprechende Darstellung ohne Dichtungsscheibe,

Figur 3

eine Darstellung des Wulstes mit Unterbrechungssegment bei der Sicht in das Innere einer Verschlußkappe.

Figur 4

eine Draufsicht auf eine Dichtungsscheibe mit einer segmentartigen Ausnehmung und

Figur 5

in vergrößertem Maßstab einen Querschnitt entlang der Linie VV in Figur 4.

Show it:

Figure 1

a cross section through a closure with bead and interruption segment,

Figure 2

1 shows a representation corresponding to FIG. 1 without a sealing washer,

Figure 3

a representation of the bead with interruption segment when looking into the interior of a cap.

Figure 4

a plan view of a sealing washer with a segment-like recess and

Figure 5

4 shows an enlarged cross section along the line VV in FIG. 4.

The screw cap shown in Figure 1 consists of a cap 1, which in turn consists essentially of a cap base 2 and a cap jacket 3 provided with an internal thread 7. There is also an at the bottom of the clasp Arranged circlip 10, which is damaged or tears off the cap 1 when the screw cap is released from a bottle for the first time.

The sectional view in Figure 1 is chosen so that on the left side the cross section of a bead 5 can be seen as a right-angled projection, while on the right side an interruption segment is shown in section, so that in this area the sealing washer 9 is not from the edge of the bead 5 is pressed downwards and inwards.

If such a closure is screwed onto the mouth edge of a bottle, a contact pressure which acts only along the edge lines occurs between the edge of the bead 5 and the upper, outer edge of the mouth edge of the bottle opposite this edge, which is relatively high because at Given the force with which the closure is screwed on, the pressure area is relatively small, as can also be seen in EP-A-0055916.

In the interruption segment 6, however, where the bead 5 is missing, the sealing disk 9 lies essentially only on the outer sealing edge of the mouth edge of the bottle due to its rigidity. The specific surface pressure is of course lower here than along the opposite edges of the bead and the edge of the mouth. Nevertheless, sufficient tightness is also achieved here, since the segment only extends over a small angular range and the sealing washer still lies more firmly in this area than if the bead 5 were completely missing.

However, the sealing disk 9 is not compressed in the region of the segment 6 or is compressed less than along the edge of the bead 5, so that it can give way in this region at a correspondingly high pressure in the bottle and allow excessive pressure to escape from the bottle, whereby also the thread 7 has ventilation channels 8 which run transversely to the threads and thus facilitate the escape of escaping gases or liquids.

Of course, the sealing washer 9 can also have a somewhat larger diameter and in some cases also rest against the inner wall of the cap shell 3, so that the seal in the region of the segment 6 can be carried out not only along the upper surface of the closure edge but also from the outside thereof.

For the sake of clarity, a similar closure cross-section is again shown in FIG. 2, in which the sealing washer 9 has been omitted, so that the cross-section of the bead 5 can clearly be seen on the right-hand side, which, depending on the point of view, can be seen in a thickened cap bottom or cap jacket wall expresses and forms a protruding corner, which causes the increased linear contact pressure. On the opposite side of the closure shown in FIG. 2, a segment is again shown cut without a bead, in which the cap wall 3 and the cap base 2 essentially maintain their other wall thickness and merge into one another with a slightly rounded 90 ° bend.

FIG. 3 shows a horizontal section through a cap 1 in the area of the bead 5. In this illustration, the wall thickness of the cap casing 3, which is greater in the area of the bead and which has its normal dimension only in the area of the interruption segment 6, can also be clearly seen. On the outside of the cap casing 3, a corrugation 12 can be seen, which is intended to facilitate screwing and screwing on the closure and is also indicated in FIGS. 1 and 2 by the outer vertical lines on the cap casing 3.

Instead of providing an interruption segment 6 in the bead 5, however, the upper side 11 of the sealing disk 9 can also have a recess in a partial area, so that accordingly the contact pressure of the sealing disk 11 on the closure edge of a bottle is also lower in this area is than in the rest of the area and overpressure can thus escape.

Figure 5 shows the top view of a sealing washer 9 with a recess 6 'on its top facing the cap bottom. In Figure 5, this recess 6 'can be seen in a cross-sectional view of the sealing washer 9. As you can see, the sealing washer 9 remains practically unchanged on its sealing underside, but in the area of the recess 6 'it rests essentially only because of its own rigidity on the sealing edge of the mouth of a bottle, while in the remaining area the protruding edge of a bead the material of the sealing washer 9 together and presses against the outer edge of the mouth of the bottle. If the pressure inside the bottle is too high, the sealing underside rises from the mouth of the bottle in the region of the recess 6 ', thus allowing the pressure to escape from the bottle until it is reduced so much that the sealing washer resumes due to its elasticity creates the edge of the rim of the mouth.

Claims (13)

1. A screw closure of plastics material for pressurised bottles for carbonated drinks, consisting of a cap (1) with a cap base (2) and a substantially cylindrical cap casing (3) with inner thread (7), at least one projection at the transition between the cap base (2) and the cap casing (3), wherein a sealing disc (9) which is movable towards the cap rests on the inside of the cap base (2) and the projection, and wherein the projection is in the form of a substantially peripheral bead (5) whose inner edge is disposed opposite the upper outer edge of the bottles, producing a substantially linear contact pressure along the peripheral bead, characterised in that the bead has a segment-like interruption (6), inside which the linear contact pressure of the seal is stopped.
2. A screw closure according to Claim 1, characterised in that the segment-like interruption of the bead extends over an arc of a minimum of 15°.
3. A screw closure according to Claim 1 or Claim 2, characterised in that the segment-like interruption extends over an arc of a maximum of 60°.
4. A screw closure according to Claim 2 and Claim 3, characterised in that the segment-like interruption extends over an arc of about 30°.
5. A screw closure according to Claim 2 and Claim 3, characterised in that the segment-like interruption extends over an angle of about 45°.
6. A screw closure according to one of Claims 1 to 5, characterised in that a plurality of segment-like interruptions (6) is arranged along the peripheral bead (5).
7. A screw closure according to Claim 6, characterised in that the segment-like interruptions each extend over equal angular regions at respectively equal angular spacings from each other along the periphery of the bead.
8. A screw closure for pressurised bottles for carbonated drinks, consisting of a cap with a cap base and a substantially cylindrical casing (3) with inner thread (7), wherein a sealing disc (9) is provided which is arranged so that is substantially on the inside of the cap base (2) and which is movable towards the cap, wherein at the transition between the cap base (2) and the cap casing (3) the cap has a substantially peripheral, inwardly projecting bead (5), the bottom inner edge of which is oppositely disposed to the upper outer edge region of the opening edge of a bottle, whereby a substantially linear contact pressure is produced between the opposite edges of the reinforcing bead and the bottle, characterised in that the upper side (11), facing the cap base (2), of the sealing disc has at least one recess in its edge region which makes contact with the opening edge of the bottle, and wherein the sealing disc and its recess extend radially out over the bottom inner edge of the bead (5).
9. A screw closure according to Claim 8, characterised in that in the region of the outer edge of the sealing disc (9) the recess extends over an angular region of a minimum of 10°.
10. A screw closure according to Claim 9, characterised in that the recess extends over an angular region of between 15 and 35°.
11. A screw closure according to one of Claims 8 to 10, characterised in that the depth of the recess is equal to at least half the thickness of the sealing disc (9) in the region next to the recess.
12. A screw closure according to one of Claims 8 to 11, characterised in that a plurality of recesses is provided along the peripheral region of the sealing disc (9).
13. A screw closure according to Claim 12, characterised in that the recesses each extend over equal angular regions in the region of the outer edge of the recess and at respectively equal angular spacings apart.

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