EP0690812B1 - Screw cap with over-tightening protection - Google Patents

Abstract

If a screw cap of a beverage bottle is over-tightened (by being turned in the wrong direction) there is the risk that, owing to the high internal pressure, not only may the thread jump but also the cap may be blown off the bottle. To prevent this, the invention proposes a screw cap with over-tightening protection. At the cap cover end of the female thread there is a leader component (3) which can engage with the thread leader of the bottle neck if the cap is overtightened. The cap wall is thus pressed outwards in the region of the leader component on over-tightening, thus facilitating jumping in this region. Hence, if over-tightening continues, the cap jumps only on one side, that of the leader compinent and the cap cannot be pushed off. In a further embodiment of the invention there are hold-open components (7, 8) in the sealing region. The deformation of the sealing region occurring during over-tightening causes said components to contact the bottle opening and the sealing lines are broken, and thus the bottle is vented even before the thread jumps.

Description

The invention relates to a screw cap made of plastic material according to the preamble of patent claim 1. Such screw caps are produced in very large quantities by injection molding and are used to close containers of all kinds. Screw caps made of plastic material have become established particularly in the area of carbonated soft drinks. The closed container can be under high pressure because the carbonated liquid it contains releases gas.

Closure caps are known which are constructed in such a way that the container is released when the closure is opened before the thread of the closure cap comes out of engagement with the container. This reduces the risk of the cap suddenly jumping off the container when opened due to excessive internal pressure.

A problem with known screw caps is the behavior when handled incorrectly. If the closure is accidentally rotated in the wrong direction to open the container, the thread is over-tightened and if the over-tightening continues, the thread may snap over. This behavior would not be a problem for containers that are not under pressure; the cap would snap a thread further up again after snapping over. If, on the other hand, the container is under pressure, as is the case with carbonated drinks, for example, the thread may not snap into place quickly enough after snapping and the cap may fly off the bottle at high speed. This behavior in the event of incorrect handling of the closure has already been in the past led to accidents.

WO-90/10581 shows a closure cap with a braking element. This is arranged on the end of the internal thread facing the cap base in such a way that it lies at least partially in the area of the screw line for the external thread. It therefore runs onto the threaded inlet of the container mouth at the end of the screwing-on process and engages with the screwed cap. Its task is to brake the unscrewing movement when the desired end position is reached. This task is performed by the seals for caps without a brake element.

It is an object of the invention to design the screw caps of the type mentioned at the outset in such a way that the risk of the cap suddenly jumping off due to overtightening of the thread is greatly reduced. This object is achieved according to the invention with a screw cap, which has the features in claim 1.

There is an overrun element at the end of the internal thread facing the cap base. The overrun element does not have to lie in the area of the thread, it can also be located outside the thread behind the thread runout. The overrun element lies outside the thread area used when the sealing cap is screwed on. It is arranged in such a way that it can be brought into engagement with the threaded inlet of the container mouth by turning the closure cap. Engaging means that the overrun element runs onto the threaded inlet of the container mouth. The overrun element is therefore at least partially in the continuation of the screw line provided for the external thread, so that when the closure cap is screwed over, it comes into the area of the thread inlet and runs onto it.

This overrun element significantly reduces the risk of the cap suddenly being pressed off when it is overtightened. The cap wall in the area of this ramp element is pressed outwards by the ramp element running onto the thread inlet. This has the consequence that the snapping of the thread on this side is made easier, since it no longer fully engages due to the cap wall being pressed outwards. The very opposite is happening on the side of the closure cap opposite the overflow segment: since the cap wall on the side of the overflow element is pressed outwards, it is pulled correspondingly stronger against the container neck; this makes it difficult to snap the thread. If you continue to overtighten, you cannot prevent the thread from snapping over, but it prevents the thread from snapping over the entire circumference at the same time. This happens first on the side of the overrun element and only then, if at all, on the opposite side. This ensures that the thread snaps back into place on the side of the overrun element before it also jumps over on the opposite side. This greatly reduces the risk of the cap being completely pressed off when the cap is overtightened.

The overrun element causes the sealing cap to deform when it is turned. This deformation can also be used to enable the container to be vented before the thread snaps over. The closure cap has at least one circumferential seal. This seal lies against the container mouth along a sealing line. The course of the sealing line can be changed when the sealing cap is turned over, the change in the course of the sealing line is a result of the deformation caused by the running-on element. The over-tightening protection of the closure cap is further improved if at least one hold-open element in the sealing area to prevent a seal is provided with a changed sealing line course. The overrun element thus indirectly prevents the container from being sealed when the cap is overturned. The deformation that occurs also increases with increasing overtightening. In order to reduce the pressure in the tank in good time, the deformation necessary to open the seals must be achieved before the thread snaps.

The specific design of the overrun element influences the force to be applied for over-tightening, as well as the deformation of the closure cap that occurs. A shape is preferred in which the overrun element extends over a sector of at least 20 °, preferably 60 °, of the closure cap. As a result, the desired deformation is achieved even if the inner radius in the region of the run-up element is only a few tenths of a millimeter below the outer radius of the container thread.

The deformation that can be achieved can be increased by increasing the thickness of the overrun element. This thickness is limited by the diameter of the container mouth to be closed, the inner radius in the area of the run-on element must be larger than the outer radius of the container mouth.

In order to take full advantage of the container thread, the cap is designed so that the outlet of the internal thread when the cap is screwed on is in the area of the thread start of the external thread. The overrun element is then preferably arranged directly behind the outlet of the internal thread.

The sealing line is a line along which the closure cap and the container mouth touch. In order to prevent the seal, it must be ensured that there is no longer a circumferential sealing line. The course of the sealing line can be changed in two ways: First, one can Sealing lip can be lifted from the container mouth in a certain area due to the deformation of the cap. The second case in which the sealing line shifts is more common. The contact point shifts away from the sealing lip to an area lying next to the sealing lip. This new contact point is now designed using at least one hold-open element in such a way that sealing at this point is prevented. In principle, this can be any type of surface profiling that is suitable for preventing a seal between the relevant support point and the container mouth. Often, a hold-open element is assigned to a special sealing lip and arranged in such a way that this sealing line is interrupted as quickly as possible when it is overtightened. In any case, the hold-open element is located in the sealing area of the closure cap, ie in the vicinity of the seals, which are generally arranged on the cap base and / or in the area of the cap wall adjoining it.

Spacer elements and / or ventilation slots are preferably used as the hold-open element. Spacers are usually shaped like a cam. They have a rather small contact surface, so that an air duct of sufficient size remains open next to the sealing element.

The deformation caused by the ramp element is not limited to the cap wall, it also affects the cap base. This undergoes a shift towards the side of the closure cap facing away from the overrun element, an amazing behavior. Since the cap wall on the side of the overrun element is pressed outward, a displacement of the cap base in this direction would also be expected. The reason for this is the different engagement of the thread on the two sides. The cap wall is pressed outwards in this area by the overrun element, the thread no longer fully engages here. On the opposite The opposite is the case, the cap wall is pulled against the neck of the container and the thread is strongly engaged. The cap wall therefore moves upwards on the side of the overrun element. It tends to skip. On the other hand, it is pulled down on the opposite side by the strongly engaged thread, which also pulls the cap base on this side. On the side of the closure cap opposite the overrun element, there is therefore a particularly pronounced change in the course of the sealing line, so that the hold-open element is preferably arranged on this side.

A type of seal which is preferably used is the face seal, which is referred to here as the head seal. It extends from the inner surface of the cap base and, when the container is closed, lies against the end of the container mouth. The seal must now be designed in such a way that the sealing line can be interrupted due to the deformation that occurs when overtightening. The easiest way to do this is to use the strong deformation of the sealing area on the side opposite the overrun element. The seal is therefore designed in such a way that the sealing lip in this area is pulled over the end face of the container mouth when it is turned. On the side of the closure cap opposite the overrun element, at least one hold-open element is arranged next to the head gasket, on the inside thereof. As soon as the sealing lip comes out of engagement with the container mouth when it is screwed over, it lies in the area of the hold-open element on the closure cap, which prevents the container from being sealed. Both a spacer element and a ventilation slot can be used as the hold-open element. In order to keep the largest possible ventilation duct open, it must be ensured that the sealing lip pulled out over the end face of the container is not in contact with the outer surface of the mouth. This can be done particularly easily by using a spacer achieve, which is arranged so that the contact force acting on it acts at least partially radially outwards. The sealing lip is thereby pushed away from the container mouth.

Another common type of seal is the inner seal. It extends from the inner surface of the cap base to the cap opening and is designed so that when the container is closed it can penetrate into the container opening and form a seal on the inner surface thereof. For this purpose, the inner seal has a sealing zone in which the diameter of the inner seal is larger than the diameter of the container opening. In this example, too, the displacement of the cap base that occurs due to overturning due to the overrun element is used to interrupt the sealing line. In principle, this can take place both on the side of the overrun element and on the opposite side of the closure cap. As already explained, the cap base is pulled onto the side of the closure cap facing away from the overrun element when it is turned over. On the side of the overrun element, the inner seal is pulled away from the inner surface of the mouth. If there is sufficient displacement of the cap base, the seal is lifted off in this area, which leads to the sealing line being interrupted. In this case, no hold-open element is required to interrupt the sealing line. However, since the seal is pre-tensioned in relation to the container mouth, this only takes place when the sealing cap is strongly deformed.

The inner seal can be opened more quickly on the opposite side of the sealing cap. For this purpose, the outer surface of the inner seal on the side facing away from the run-on element has at least one hold-open element, which is arranged on the side of the sealing zone facing the cap bottom. The radius of the inner seal in the area of the hold-open element is only a little smaller than in the area of the sealing zone so that it does not touch the container mouth when the cap is on. By shifting the cap base when the cap is turned, the seal in this area is pressed more strongly against the inner wall of the container mouth. Since the seal touches the container mouth in the area of the sealing zone, it holds its position at this point. On the other hand, it does not touch the container mouth in the area of the cap base, this area of the seal is therefore moved with the cap base in the direction of the container wall. This limitation of the displacement to the cap bottom inevitably leads to an inclination of the inner seal. The hold-open element approaches the inner surface of the mouth. If there is sufficient deformation, the inner seal lies in the area of the hold-open element at the container mouth, the sealing zone is thereby lifted from the container mouth. A knob-shaped spacer is preferably used as the hold-open element. As a result, the seal can be made much thinner, only in the area of the spacer element does it approximately reach the radius of the sealing zone. The freedom of movement required to tilt the seal is also retained.

As a rule, several sealing lips are used in combination in the case of closure caps of the type mentioned. For example, an inner seal, a head seal and an outer seal can be used. Accordingly, the design variants listed can also be used in combination. The principles outlined can also be applied to sealing variants not shown here.

The reliability of the overturn protection can be further improved if several hold-open elements are arranged distributed over a sector of at least 20 ° of the closure cap. The hold-open elements are preferably distributed over a sector of approximately 60 ° of the closure cap.

Distributing the hold-open elements over a larger sector allows a larger ventilation duct to be opened when overtightening. This speeds up the ventilation of the container.

Fig. 1

den Querschnitt durch eine Verschlusskappe gemäss Ebene A-A in Figur 2,

Fig. 2

die Ansicht der Innenseite einer Verschlusskappe,

Fig 3

die Schnittdarstellung einer Behältermündung mit aufgeschraubter Verschlusskappe,

Fig. 4

die Schnittdarstellung der Behältermündung gemäss Fig. 3 mit 45° überdrehter Verschlusskappe,

Fig. 5

die Schnittdarstellung der Behältermündung gemäss Fig. 3 bei 90° überdrehter Verschlusskappe,

Fig. 6

eine vergrösserte Darstellung des Dichtungsbereichs der Anordnung gemäss Figur 5 auf der dem Auflaufelement gegenüberliegenden Seite,

Fig. 7

den Dichtungsbereich einer 90° überdrehten Verschlusskappe auf der dem Auflaufelement gegenüberliegenden Seite, und

Fig. 8

eine Anordnung gemäss Figur 5 nach dem Überschnappen der Verschlusskappe.

The invention is explained in more detail below with the aid of examples. Show it:

Fig. 1

3 shows the cross section through a closure cap according to plane AA in FIG. 2,

Fig. 2

the view of the inside of a cap,

Fig 3

the sectional view of a container mouth with screwed cap,

Fig. 4

3 shows the sectional view of the container mouth according to FIG. 3 with the closure cap overturned by 45 °,

Fig. 5

3 shows the sectional view of the container mouth according to FIG. 3 with the closure cap overturned by 90 °,

Fig. 6

5 shows an enlarged representation of the sealing area of the arrangement according to FIG. 5 on the side opposite the overrun element,

Fig. 7

the sealing area of a cap overturned by 90 ° on the side opposite the overrun element, and

Fig. 8

an arrangement according to Figure 5 after snapping the cap.

1 shows the sectional view of a closure cap according to plane AA in FIG. 2. The cap consists of a cap base 1 and a cap wall 2 adjoining it.

To seal the container mouth, it has three seals: an outer seal 4, an end-acting head seal 5 and an inner seal 6. On the inner surface of the cap wall, a run-up element is arranged on the side of the internal thread facing the cap bottom. Spacer elements 7, 8, which serve as a hold-open element, are arranged in the sealing area on the side of the closure cap opposite the overrun element.

Figure 2 shows the view of the inside of a closure cap. The overrun element has the shape of a circular ring sector, which extends over a sector α of 60 ° of the closure cap. This is arranged directly behind the thread outlet 11. When the cap is screwed on, the beginning of the container thread engages with the threaded outlet 11. It is therefore just in front of the overrun element 3. If the closure cap is turned over, the overflow element comes into engagement with the threaded inlet of the container mouth. On the side opposite the overrun element, a plurality of spacer elements 7, 8 are arranged distributed over a sector β of 60 ° of the closure cap. The internal thread has a plurality of ventilation slots 9 which run approximately parallel to the cap axis. These allow gas to flow off easily if the container is ventilated by opening the seals.

Figure 3 shows the sectional view of a container mouth with the cap attached. The three sealing lips 4, 5, 6 lie all around the container mouth and hermetically seal it.

FIG. 4 shows the sectional view of the container mouth according to FIG. 3 with a closure cap overturned by 45 °. The casserole element 3 has run onto the threaded inlet 12 of the container mouth. The cap wall 2 is thereby in the area of the ramp element 3 from the outer surface of the container mouth depressed so that the internal thread is less engaged with the container thread. This makes it easier to snap the thread in the area of the overrun element. On the opposite side of the closure cap, facing away from the overrun element, the cap wall is pulled correspondingly stronger against the container wall. The internal thread is therefore strongly engaged with the external thread of the container. Due to the screw action of the thread, the cap wall in this area of the closure cap is pulled downward more strongly onto the container during the overturning. This results in a deformation of the sealing area, in particular on the side facing the run-up element. The outer seal 4 is lifted off the outer surface of the container mouth and the sealing line of the head seal 5 is drawn towards the outer edge of the end face 16. The cap base 1 also moves onto this side facing away from the overrun element, which leads to the inclination of the inner seal on this side. The spacer elements 7 are brought closer to the inner surface 13 of the mouth.

Figure 5 shows the sectional view of the container mouth according to Figure 3 with a cap which is turned 90 °. In comparison to FIG. 4, which shows the same closure arrangement with only a 45 ° overturned condition, a significantly greater deformation of the sealing area can be found here, in particular on the side opposite the overrun element. The sealing lip of head 5 is pulled out over the outer edge of the mouth face. It does not touch the container in this area. Instead, the spacer elements 8 are now in contact with the outer edge of the mouth end face and thus effectively prevent a seal in this area of the container mouth. Compared to the state shown in FIG. 4, the cap base is further shifted to the side facing away from the overrun element. This made the inclination of the inner seal further reinforced, so that the spacer elements 7 now lie against the inner surface of the mouth. The actual sealing zone of the inner seal 6 is thereby pressed off the inner surface of the mouth in the area of the spacer elements 7. The sealing line of the inner seal is thus also interrupted and the spacer elements 7 prevent a seal in the area of the inner seal. Basically, it is sufficient to ventilate the container to ensure that there is no longer any circumferential sealing line. The variant shown in this example has the special advantage that all sealing lines are interrupted in the same circumferential area, namely on the side opposite the overrun element. This creates a particularly direct ventilation duct.

FIG. 6 shows an enlarged illustration of the sealing area of the arrangement according to FIG. 5 on the side opposite the ramp element. The closure cap touches the container mouth 14 only in the area of the spacer elements 7, 8. Gas in the container can therefore escape, as indicated by the arrows 17. The spacer element 8 acts both in the axial and in the radial direction. It thus prevents both a seal in the area of the end face 16 and a seal on the outer face by the displaced sealing lip of the head gasket 5.

FIG. 7 shows the sealing area of a closure cap overturned by 90 ° on the side opposite the overrun element. This ventilation slot begins next to the sealing lip of the head gasket 5. Its length 18, at least in the case of a deformed sealing area, is greater than the thickness 19 of the container mouth, so that it prevents a seal in the area of the mouth end face.

FIG. 8 shows an arrangement according to FIG. 5 after the closure cap 5 has been snapped over. This occurs at an overtightening angle of about 90 °. The thread snaps on one side on the side of the overrun element, while it remains firmly engaged on the opposite side. This tendency can also be seen from FIGS. 4 and 5. This ensures that the internal thread can snap back into place even after increased snap-in pressure, and the cap remains on the container. In fact, however, there is no increased internal pressure at the moment of snap-over, since this was previously derived in accordance with the explanations for FIGS. 5 to 7.

Claims (11)

1. A screw-on closure cap of plastics material having a cap end portion (1) and a cylindrical cap wall (2) adjoining same with a female screwthread for closing a container mouth opening with a male screwthread, having a run-on element (3) for limiting the screwing-on movement which is arranged at the end of the female screwthread that is towards the cap end portion (1) and which is at least partially disposed in the region of the helical line for the male screwthread, and having at least one peripherally extending seal (4, 5, 6) for sealing the container mouth opening along a sealing line, characterised in that the configuration of the sealing line can be altered by the run-on element (3) when the closure cap is screwed on over the run-on element, and at least one holding-open element (7, 8, 15) arranged in the sealing region prevents the sealing effect when the sealing line configuration is altered.
2. A closure cap according to claim 1 characterised in that the run-on element (3) extends over a sector (α) of at least 20° of the closure cap.
3. A closure cap according to claim 1 or claim 2 characterised in that the run-on element (3) is arranged directly behind the screwthread exit (11).
4. A closure cap according to one of claims 1 to 3 characterised in that the holding-open element (7, 8) is arranged on the side of the closure cap, that is opposite to the run-on element (3).
5. A closure cap according to one of claims 1 to 4 characterised in that at least one holding-open element is a spacer element (7, 8).
6. A closure cap according to one of claims 1 to 4 characterised in that at least one holding-open element is a venting slot (15).
7. A closure cap according to one of claims 1 to 6 characterised in that one of the seals is a head seal (5) which extends from the inside surface of the cap end portion for sealing the container mouth opening at the end thereof and that arranged on the side of the closure cap that is opposite to the run-on element (3) beside the head seal (5) at the inside thereof is at least one holding-open element (8).
8. A closure cap according to one of claims 1 to 7 characterised in that one of the seals is an inner seal (6) which extends from the inside surface of the cap end portion and whose outside surface has on the side that is remote from the run-on element (3) at least one holding-open element (7) which is arranged on the side of the sealing zone that is towards the cap end portion.
9. A closure cap according to one of claims 1 to 8 characterised in that a plurality of holding-open elements (7, 8, 15) are arranged distributed over a sector (β) of at least 20° of the closure cap.
10. A closure cap according to claim 9 characterised in that the holding-open elements (7, 8, 15) are arranged distributed over a sector (β) of about 60° of the closure cap.
11. A closure cap according to one of claims 1 to 10 characterised in that the female screwthread has venting slots (9) extending approximately parallel to the cap axis.

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