CN1277590A - Plastic screw cap for closing a bottle or the like - Google Patents

Abstract

The invention relates to a plastic screw cap for closing a bottle or the like. The inventive cap comprises a cylindrical screwing part which has an inner thread for screwing onto an outer thread of a bottle neck. The inventive cap also comprises a sealing lip (24) which extends diagonally outward from the base of the screw cap, and a conical sealing surface (26) which fits closely on an external sealing edge (28) of the facing surface (16) of the bottle mouth when the screw cap (2) is screwed on. Recesses (32) are provided in the conical sealing surface (26) which extend from an area, said area lying closely outside the sealing edge (28) when the screw cap (2) is screwed on, to the rim (34) of the sealing lip (24) and are connected to the outside. With the dome-shaped convexity of the base (6) of the screw cap (2), the sealing lip (24) slides with the sealing surface (26) of the screw cap (2) onto the sealing edge (28). When the pressure in the bottle along with the bulging of the base (6) are sufficiently large, the recesses (32) enter the area of the sealing edge (28) and create a penetration from the inside of the bottle to the outside such that the excess pressure can be released. The constructed excess pressure valve possesses characteristics which can be exactly defined and are lasting.

Description

Plastic screw caps for closing bottles or the like

The invention relates to a screw cap of the type stated in the preamble of claim 1 .

Known by DE 4226935A1 is a screw cap of the type concerned, which has a cylindrical helical part with an internal thread for being screwed onto the external thread of the bottle neck, wherein a screw cap extends obliquely outwards from the bottom of the screw cap. The sealing lip has a sealing surface for leaning against the end face of the bottle mouth. Furthermore, means are provided for determining the screw-on position of the screw cap; they consist of annular end faces which, when screwed on, bear against the end face of the bottle neck and thus limit further screwing in. The clamping force of the sealing lip between the bottle neck end face and the bearing surface arranged behind the sealing lip can be adjusted by suitably positioning the annular end face. This clamping does not take place over the entire circumference; rather, there is a recess at least one place behind the sealing lips, so that they bulge in the recess when the pressure increases so that excess pressure can escape. In the region of the groove the sealing lip rests solely on the basis of its inherent elasticity plus its pretension. The disadvantage of this is that, since plastics are also partly plastic, the elastic force and thus the fit of the sealing lip decreases over time, so that the seal is already loose at low overpressure inside the bottle, resulting in inaccurate The desired liquid flows from the bottle. Furthermore, the pressure at which depressurization occurs to prevent the bottle from bursting can only be adjusted inaccurately.

Known from DE 3839351 A1 is a screw cap similar to the type in question, which differs from the screw cap described above only in that the sealing lip is replaced by a built-in seal. The known screw caps therefore also have the same disadvantages.

A plastic screw cap is known from US 4360077, wherein two annular seals extend substantially axially from the bottom of the screw cap, and in the tightened state they should seal the edge of the bottle neck outlet between them. The two sealing lips have venting slots on their edges, which are meaningless when the screw cap is fully screwed on, but when the screw cap is unscrewed, the internal pressure should escape from the bottle through the venting slot not suddenly but gradually . Explosive deflation can thus be prevented. However, no pressure relief valve is formed here.

The object of the present invention is to create a screw cap of the type stated in the preamble of claim 1 which has the effect of a pressure relief valve in a simple manner permanently and efficiently.

The object of the invention is achieved by the principle stated by the features of claim 1 .

The basic idea according to the principle of the invention is that instead of forming the pressure relief valve by means of an elastic deflection of the seal, the pressure relief valve is actuated by means of a dome-shaped deformation of the base and the adjacent edge region of the cylindrical helical part due to internal pressure. For this purpose, the sealing surface of the sealing lip is substantially conical in shape, which bears against the outer sealing edge of the bottle mouth end face when the screw cap is screwed on. With this design and orientation of the sealing lip, since it is connected to the bottom of the screw cap, the sealing lip performs a sliding movement on the outer sealing edge of the bottle mouth end face when the bottom becomes dome-shaped, depending on the internal pressure of the bottle .

This sliding movement results in the use of an overpressure valve according to the principle of the invention, for which at least one groove is provided in the conical surface, the groove extending from a position immediately outside the sealing edge when the screw cap is screwed on. The area extends towards the edge of the sealing lip and communicates with the external environment. If the bottom of the screw cap is dome-shaped outwards beyond the specified amount, the groove in the conical sealing surface of the sealing lip reaches the area of the outer sealing edge of the end face of the bottle mouth, thereby forming a gap between the inner cavity of the bottle and the external environment. Channel through which the pressure can be relieved. As a result of the pressure relief from the inside of the bottle, the dome-shaped elevation of the base recedes, so that the recess in the conical sealing surface also leaves the region of the sealing edge of the bottle finish again, and the channel, ie the pressure relief valve, closes again.

By determining the length of the sealing lip, the inclination angle of the bearing surface and the distance between the groove and the sealing edge, the discharge pressure can be adjusted in a large range.

In the case of the dome at the bottom of the bottle, its edge shrinks slightly inwards due to the secant shortening, and at the same time drives inwards the adjacent area of the cylindrical helical part, thus supporting the dome at the bottom and The sliding movement of the sealing lip connected to it.

Expediently, the recess in the conical sealing surface is a radial passage, which represents the shortest path from the formed opening region of the pressure relief valve to the environment.

According to a further development of the invention, a gap is formed between the cylindrical spiral part and the bottle neck in the outlet region of the bottle neck. This ensures that the radial inward movement of the bottom edge of the screw cap and in particular the adjacent region of the cylindrical screw part is not impeded by the peripheral surface of the bottle neck even with large deflections.

The sealing lip preferably has a substantially constant thickness at least up to the groove. As a result, the bearing pressure does not change during the sliding movement below the venting pressure of the formed pressure relief valve, so that the sealing force is always of the same magnitude and thus prevents leaks below the venting pressure.

According to a further advantageous development according to the invention, on the side of the sealing lip facing away from the conical sealing surface, a sealing lip support surface runs parallel to the conical sealing surface just behind the sealing lip. Although the sealing lip can in principle have enough self-stiffness to ensure that there is still a large enough supporting force even in the process of sliding movement of the sealing lip in the tightened state, so that no matter what pressure the sealing lip occurs, it will not break from the end face of the bottle mouth. The sealing edge is raised, but greater material thickness and greater material consumption are required for this. If, on the other hand, the sealing lip can be supported on its rear side on a support surface, the sealing lip can be considerably thinner, since the supporting force is always sufficiently high to prevent the sealing lip from coming off under any pressure. Thus, even with a thin sealing lip, the sealing from the inside of the bottle to the surrounding environment is always only possible when the groove in the conical sealing surface slides into the area of the outer sealing edge of the finish and thus creates a passage from the inside of the bottle to the environment. Deflate outside. An additional advantage of this embodiment is that the opening pressure is independent of the torque used to tighten the screw cap, so that no stop is necessary which prevents overtightening. However, in all embodiments of the invention it may be advantageous to have such a stop.

In principle, a recess on the conical sealing surface is sufficient to ensure the function of the pressure relief valve. Of course, with only one groove, only a small deflation cross section is formed. For this reason, it is expedient to provide a plurality of grooves distributed along the entire circumference of the sealing lip.

According to a development of the invention, the screw cap has a weakening in a region adjacent to the sealing edge when the screw cap is screwed on, which is preferably formed by an annular groove in the base and lies radially outside the sealing edge. This weakening should facilitate the dome-shaped deformation of the bottom due to the internal pressure and thus increase the sliding movement of the sealing lip used according to the invention on the outer sealing edge of the bottle finish and thus improve the effect of the pressure relief valve .

The invention will be explained below with the aid of an exemplary embodiment represented in the drawing. Which means:

Fig. 1 is screwed on the sectional view of a screw cap embodiment on the bottleneck;

Figure 2 The enlarged view of the left half of the screw cap in the closed position of Figure 1;

Figure 3 corresponds to Figure 2 but shows the screw cap in the overpressure valve open position; and

FIG. 4 corresponds to the representation according to FIG. 2 but shows a variant of the embodiment according to FIG. 1 .

FIG. 1 shows a cross-sectional view of a screw cap 2 comprising a cylindrical screw part 4 and a bottom 6 . The screw part 4 is formed with an internal thread 8 which engages with an external thread 10 of the neck 12 of the bottle. Stops 14 are located on the inner side of the base 6 , which bear against the front face 16 of the bottle neck 12 and thus define the screw-in depth of the screw cap 2 on the bottle neck 12 . The securing ring 20 is connected to the screw part 4 via the material connecting part 18 . When the screw cap 2 is unscrewed for the first time, the material connecting portion 18 is torn off, thereby clearly indicating that this is the first opening, and then the securing ring 20 is detached from the screw cap 2 .

The sealing lip 24 extends obliquely outwards from the inner surface 22 of the bottom 6 and forms a conical sealing surface 26 which rests against the outer sealing edge of the outlet end face 16 of the bottle neck 12 in the screwed-on state shown in the left half of FIG. 28 on. In this case, the sealing lip 24 is clamped between the sealing edge 28 and the conical bearing surface 30 , the bearing surface 30 being substantially parallel to the sealing lip when the sealing lip 24 rests on the sealing edge 28 in the tightened state. 24 sealing surface 26.

There is a groove 32 in the conical sealing surface 26, and when there is no high overpressure in the bottle after the screw cap 2 is screwed on, the groove 32 starts from a position immediately outside the sealing edge 28 after the screw cap 2 is screwed on. The region extends as far as the edge 34 of the sealing lip 24 .

FIG. 2 is an enlargement of the left half of FIG. 1 in order to clearly see the situation when the screw cap 2 is screwed on and there is no excessive internal pressure. In particular, it can be seen in this enlarged view that the groove 32 extends from an area immediately outside the sealing edge 28 to the edge of the sealing lip 24 . This means that the sealing lip 24 is clamped between the sealing edge 28 and the bearing surface 30 and thus produces a good seal with a high sealing force, which is independent of the elastic properties of the sealing lip 24 .

FIG. 3 corresponds to FIG. 2 , but shows the situation during pressure relief, in which case the formed pressure relief valve is open. It can be seen that the bottom 6 bulges in a dome shape under the action of internal pressure. Therefore, the bottom edge and the adjacent area of the helical part 4 connected thereto move radially inwards, as indicated by the arrow 36 in the figure. At the same time, the root 38 of the sealing lip 24 moves axially generally in the direction of the protrusion, as indicated by the arrow 40 . These two movements in the directions of arrows 36 and 40 result in a movement of the root 38 of the sealing lip 24 in the direction of the arrow 42, which causes a sliding movement of the sealing lip 24 between the sealing edge 28 and the bearing surface 30, resulting in a The recess 32 extends into the region of the sealing edge 28 and thus forms a passage from the bottle interior to the environment, through which overpressure can be relieved, in which case the inner thread 8 and the outer thread 10 do not constitute an obstacle. After the depressurization, the dome-shaped bulge of the bottom 6 recedes again, the movement proceeds in the direction opposite to the arrows 36, 40 and 42, and thus the groove 32 again reaches the previously formed groove outside the region of the sealing edge 28. The channel is closed again.

FIG. 4 shows a variant of the embodiment according to FIG. 1 in a view according to the representation shown in FIG. 2 . The same or corresponding parts adopt the same reference numerals. The difference is that an annular groove 44 is provided in a region of the base 6 radially outside the outer sealing edge 28 of the outlet end face 16 of the bottle neck 12 . This groove 44 is located on the side of the bottom 6 facing the sealing lip 24 . This groove 44 facilitates the dome-shaped bulging of the bottom of the bottle under the action of internal pressure, increases the sliding movement of the sealing lip 24 and improves the function of the pressure relief valve. A groove 46 in the inner wall of the cylindrical screw part 4 adjacent to the bottom 6 of the screw cap 2 also serves the same purpose.

Claims (12)

1. the plastic screw cap used of closed bottle or analogue, comprise-cylindrical spiral part, it has the negative thread that is screwed on the bottleneck outside thread, and-sealing lip that tiltedly extends from screw top bottom lean-out, it has a sealing surface that abuts on the bottleneck end face, it is characterized by: the sealing surface (26) of-sealing lip (24) is cylindrical-conical basically, and it abuts on the outer gland sealing limit (28) of bottleneck end face (16) when the screw top of screwing on (2); And-in conical sealing surface (26), establish at least one groove (32), it is in the zone that is right after outside sealing lip (28) from one and extends towards sealing lip (24) edge (34) and and external environment connect when tightening screw top (2).

2. according to the described screw top of claim 1, it is characterized by: groove (32) is a radial passage in conical sealing surface (28).

3. according to the described screw top of claim 1, it is characterized by: the outlet area at bottleneck between cylindrical spiral part (4) and bottleneck (12) forms a space.

4. according to the described screw top of claim 3, it is characterized by:, in the inwall of cylindrical spiral part (4), be close to screw top (2) bottom (6) and locate to be shaped at least one circular groove in order to form this space.

5. according to the described screw top of claim 1, it is characterized by: sealing lip (24) has the thickness of substantial constant at least until groove (32).

6. according to the described screw top of claim 5, it is characterized by: at sealing lip (24) back to that side of conical sealing surface (26) just in the sealing lip back, extend the areal of support (30) of a sealing lip (24) parallel with conical sealing surface (26).

7. according to the described screw top of claim 6, it is characterized by: the angle of conical areal of support (30) is less than 90 °.

8. according to the described screw top of one of all claims in prostatitis, it is characterized by: establish backstop (14) on screw top (2), it abuts on the part bottleneck (12), is used for determining the position of tightening of screw top (2).

9. according to the described screw top of claim 1, it is characterized by: screw top (2) has a weakened part in a zone that is in sealing lip (28) adjacency after tightening screw top (2).

10. according to the described screw top of claim 9, it is characterized by: the weakened part is made of a circular groove in bottom (6).

11. according to the described screw top of claim 9, it is characterized by: the weakened part radially is positioned at outside the sealing lip (28).

12. according to the described screw top of claim 9, it is characterized by: the weakened part is by constituting in the face of the groove (43) on that side of sealing lip (24) in bottom (6).

Images