WO1995029100A1

WO1995029100A1 - Reclosable beverage can closure with improved pressure seal

Info

Publication number: WO1995029100A1
Application number: PCT/IB1995/000250
Authority: WO
Inventors: Ronald L. Kelly; Michael L. Price
Original assignee: Crown Cork & Seal Company, Inc.
Priority date: 1994-04-25
Filing date: 1995-04-10
Publication date: 1995-11-02
Also published as: AU2081995A; IL113215A0; JO1848B1

Abstract

A beverage can closure assembly with an improved pressure seal includes an insert (8) hermetically installed in the can top (2), and a closure (4) comprising a plug (14) received in an aperture in the insert. A plate portion of the closure, above the plug, has an outwardly extending rim whose lower surface abuts the top of the insert when the plug is screwed into the insert. A good seal is obtained by providing a groove (15) in the bottom surface of the rim and a complementary bead on the insert, around the aperture. The bead has an interference fit in the groove when the plug is secured in the insert.

Description

Reclosable beverage can closure with improved pressure seal

BACKGROUND OF THE INVENTION This invention relates generally to containers, and more particularly to a beverage can closure with an improved pressure seal.

Resealable closures are known for many type of containers; however, no resealable closure for beverage cans has yet proved practicable. Therefore, beverage cans are in most cases limited to the size of a single serving, and may be regarded as "user- unfriendly", since they essentially force one to discard any beverage not consumed at the first sitting.

SUMMARY OF THE INVENTION

An object of the invention is to create a closure device which can be simply attached to a can top during manufacture of the can, will seal reliably until the can is opened, and can be resealed thereafter.

Another object of the invention is to provide such a clo¬ sure with a tamper-evident feature.

These and other objects are attained by a beverage can closure assembly with an improved pressure seal as described below. The assembly includes an insert hermetically installed in the can top, and a closure comprising a plug insertable into an aperture in the insert. A plate portion of the closure, above the plug, has an outwardly extending rim whose lower surface abuts the top of the insert when the plug is screwed into the insert. A good seal is obtained by providing a groove in the bottom surface of the rim and a complementary bead on the insert, around said aperture. The bead has an interference fit in the groove when the plug is secured in the insert. BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings.

Figure 1 is a top plan view of a closure embodying the invention;

Figure 2 is a cross-sectional view of a can top, taken on the plane A-A in figure 1;

Figure 3 is a portion of Figure 2, with force vectors added to show forces at work on the closure, absent internal can pressure;

Figure 4 is a view like Figure 3, showing an uncapping force resulting from internal pressure, and reaction forces developed in response; and

Figure 5 is an enlarged detailed view of a portion of Figure 2, with the parts separated, showing a sealing groove aligned with a sealing bead.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The closure 1 shown in Figure 1 includes a flat-topped plate of substantially uniform thickness (see Fig. 2). The plate, as seen in Figure 1, includes a disk-shaped portion 4 with a broad radially extending lever or tab 9 to facilitate opening of the can.

A plastic fitting 8 is injection molded and then installed in a hole in the can top 2. It may be also installed by molding it in place. The fitting has a central pouring aperture 3, initially sealed by the closure. The closure 1 and fitting together form an assembly embodying the invention.

The closure is preferably tethered to the can by a narrow, flexible bight of material 5 connected at one end to the side of the tab, and at the other end to an anchor 7 which is perma¬ nently affixed to the insert 8, or to the cap top. The tether 5 must be long enough to permit sufficient rotation of the closure to open and close it. In the case of the bayonet connection mentioned below, about 35° of movement is needed.

The closure element 4, the tether 5 and the anchor 7 are injection molded as a single component. The anchor is preferably secured by a pin extending upward from the fitting through a hole in the anchor; the top of the pin is then flattened by heating it. Alternatively, the an¬ chor could be welded to the can top or secured by an adhesive.

The anchor is directly connected to the closure by a series of bridges 10, separated by narrow slots extending along the edge of the closure. When the closure is opened for the first time, the bridges break to provide tamper indication. The flexible tether 5 thereafter keeps the closure from being lost or discarded.

An annular plug 14 extends downward from the bottom surface of the plate, at the center of the disk-shaped portion. The plug is substantially smaller in diameter than the disk-shaped portion of the plate, so that the periphery of the disk-shaped portion forms a rim extending radially beyond the plug and over the fitting.

There is a rotary connection, preferably a bayonet-type connection, between the plug and the insert 8. The pair of external protrusions shown in Figure 2 at the bottom of the plug pass vertically through corresponding cutouts (not shown) in the insert 8, and lock below ramp elements near the bottom of the insert's central aperture when the closure is twisted clockwise. While a bayonet connection is preferred, any screw-type connec¬ tion can be used. For example, a helical thread connection could be substituted for the bayonet connection, without deviat¬ ing from the principles of the invention.

The bottom of the rim has a groove 15 formed in it, running around and spaced from the plug 14. This groove receives a like-diameter circular bead 16 molded on the top of the insert. The geometry of the groove and the bead are important to achieving a good seal.

In the presently preferred embodiment of this invention, the inner and outer walls 19 of the groove are vertical (i.e., sections of vertical cylinders), while the sides 22 of the bead are frustoconical, converging in the upward direction. Each bead side forms an angle of less than 5° with the vertical,preferably about 3°. The top 20 of the groove, and the top 21 of the bead are flat, and parallel, so that they abut and provide sealing when the closure is screwed down tightly.

Because of the taper of the bead sides, the bead's wall thickness grows in the downward direction. Dimensions are chosen so that, at least at its base, the width of the bead is greater than that of the groove. Thus, the bead 16 wedges into the groove 15 when the cap is installed, developing high sealing forces on either side of the bead wall. Also, the wedging effectively unites the closure and the insert, producing a stable assembly.

If pressure builds up within the can, for example from beverage carbonation, an uncapping force P is developed on the the plate 18, as shown in Figure 4, which is a simplified view omitting the plug. The bending or bulging is exaggerated. As the diagram shows, the uncapping force P is resisted by a sta¬ bilizing force F_f provided by the bayonet connection. If the pressure is sufficient to bend the plate upward, as shown in Figure 5, sealing is not adversely affected, even though contact between the top of the groove and the top of the bead might be interrupted. The wedging forces on the sides of the groove and the bead, however, actually increase as the top bends because of the force couple which arises, resisting the bending, at the bead-groove interfaces, as shown. The increased forces, F₀ in particular, augment the sealing effect of the closure.

While the bead has been described above as tapered, and the groove as having vertical walls, one could reverse that arrange¬ ment, making the groove tapered. Also, while the groove has been described as being formed in the closure plate, the dispo¬ sition of the bead and groove could be reversed, that is, the groove could be formed on the insert.

The insert is preferably formed of plastic as mentioned, but other materials and methods of manufacture may prove to be workable variations of this invention.

"Vertical" has been used above for simplicity and clarity. It should be understood to mean the direction of the can axis. regardless of the can's actual orientation.

Since the invention is subject to modifications and varia¬ tions, it is intended that the foregoing description and the accompanying drawings shall be interpreted as illustrative of only one form of the invention, whose scope is to be measured by the following claims and subcombinations thereof.

Claims

What is claimed is:

1. A closure assembly with an improved pressure seal for seal¬ ing a beverage can top, said assembly comprising a fitting extending through a hole in the can top, the fitting having an aperture through which a liquid can be poured from the can, a closure comprising a plug insertable into said aperture, and a plate portion above the plug, said plate having a portion extending outward of the plug, forming a rim having a lower surface, means on the plug, and on the insert, defining a screw-type connection therebetween, whereby the plug is twisted in one direction to secure it in the insert, and in the opposite direc¬ tion to remove it, and sealing means comprising a groove formed in the bottom surface of said rim and extending around said plug, and a com¬ plementary bead formed on the insert, around said aperture, at least a portion of the bead having an interference fit in the groove when the plug is secured in the insert.

2. The invention of claim 1, wherein the groove has opposite sides which are substantially parallel.

3. The invention of claim 1, wherein the screw-type connection is a bayonet connection having interlocking parts on the closure plug and on the insert.

4. The invention of claim 1, wherein the fitting is defined in a plastic insert mounted in the hole in the can top.

5. The invention of claim 4, wherein the groove has a planar top surface perpendicular to its opposite sides and parallel to said bottom surface of the plate and to a top surface of the insert. - 7 -

6. The invention of claim 5, wherein the bead has upwardly converging opposite sides with an acute convergence angle there¬ between, and the bead has an interference fit in said groove.

7. The invention of claim 6, wherein the convergence angle is less than five degrees.

8. The invention of claim 7, wherein the convergence angle is about three degrees.