Child-resistant closure

Abstract

A substantially leak-proof and child-resistant combination closure comprising a container and a cap. The container has a threaded neck and the cap has a tubular skirt with mating threads on its inner surface, a disc-like top and resilient annular shoulder portion. There is a sealing liner beneath the top of the cap which engages and seals the open end of the container neck. The cap skirt and the container have cooperating locking means which are engaged when the cap is turned down to normal closed position. The locking means function both to render the closure child-resistant and to stop the relative rotation of the cap onto the container at a predetermined angular position where the locking means is effective. The resilient shoulder of the cap flexes to compensate for tolerance variations in the threads of the cap and container neck in order to insure that the cap liner seals the neck of the container.

Description

BACKGROUND OF THE INVENTION

With the current emphasis that has been placed upon protection of children of tender ages from harm due to their being able to open containers of medicines, acids, soaps, etc., development of so called "child-proof" or, more correctly, "child-resistant" containers and closures, has been very rapid.

Many of these child-resistant combinations have employed threaded caps and containers with threaded necks, the caps and containers being provided with cooperating means which function to prevent the child of tender years from removing the cap from the container after it has been seated thereon.

Devices of this type which are practical also must be so designed as to provide for capping the containers by the use of conventional capping equipment. Since may products to be so packaged have previously been packaged in vials or glass bottles with threaded necks and simple screw-on caps most packaging organizations already possess capping equipment which is capable of placing such caps onto bottle necks with a fixed torque so that the caps will be securely seated on the bottle necks by the capping machines.

However, the tolerances of manufacturing of both the bottles or vials and the caps or closures are such that even when the caps are put on by automatic, constant torque capping machines, they do not all reach the same angular position relative to the containers on which they are set by the capping machines.

If the caps or closures have internal sealing liners, which function to render the necks of the containers leak proof, variations in the degree of tightening of the caps onto the necks of the bottles may be important as a result of cumulations in the tolerances. When cork was inexpensive, because it is highly resilient and does not take a "set" if it is squeezed too tightly, it frequently was utilized as the main body of the sealing liners so that it would compensate easily for these variations and would maintain all of the containers in liquid tight condition even if the caps or closures were put on various containers with different torque and thus squeezed the liners to differing degrees.

When the cap of the child-resistant closure is designed, however, it is necessary that the cap be rotated onto the container to a distance sufficient to insure that the cooperating means will engage and thus prevent the cap from being unscrewed by a small child. However, because of the variations in the tolerances such caps may be turned onto the containers by the capping machine or by an adult to positions beyond the positions where the locking means engage. If this occurs, the liner may be squeezed too tightly and take a "set." Upon a subsequent replacement of the cap, if it is not turned on as far, the liner will not expand to maintain the seal.

In order to avoid the foregoing common problem, it has been suggested that the cap and container comprise means for stopping the rotation of the cap onto the container at the precise position where the child-resistant locking means engage. Again, however, because of the cumulation of tolerances problem, when the rotation of the cap is stopped at a fixed position, the liner may not be in sealing contact with the neck of the container.

It is the object of the instant invention, therefore, to provide a child-resistant closure for a container in which the cap and container have cooperating child-resistant locking means engaged at a certain relative angular position of the cap on the container and in which the locking means also prevent the cap from being turned beyond locking position and the cap has a resilient shoulder which compensates for variations in cumulated tolerances to insure that the liner seals the container neck when the cap reaches the fixed or predetermined locking position on the container at which the child-resistant locking means are engaged.

These and other more specific objects and advantages of a closure embodying the invention will be better understood from the specification and from the drawings which follow.

DESCRIPTION OF THE DRAWINGS

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

FIG. 2 is a fragmentary view in vertical elevation, with parts broken away of the closure shown in FIG. 1;

FIG. 3 is a fragmentary, vertical sectional view with parts broken away taken along the line 3--3 of FIG. 2;

FIG. 4 is a fragmentary side view in elevation showing how the child-resistant locking means is disengaged to permit removal of the cap from the container;

FIG. 5 is a view similar to FIG. 2 and illustrating how the closure of the combination of the invention may be distorted to insure sealing engagement of its liner against the open neck of the container.

DESCRIPTION OF PREFERRED EMBODIMENT

A substantially leak-proof and child-resistant closure combination according to the invention comprises a container 10 which has a generally cylindrical body portion 11, a threaded neck 12 and an annular shoulder 13 joining the wall of the body 11 to the base of the neck 12.

An inverted cup-shaped cap 14 has a tubular skirt 15, a disc-like top 16 and a resilient annular shoulder portion 17 connecting the disc-like top 16 and the skirt 15. The cap 14 also has threads 18 formed on the inner surface of its skirt 15 to mate with the threads on the neck 12 of the container 10.

A disc-like liner 19 is positioned against the inner side of the cap top 16 and is of such size as to close and seal the open center of the container neck 12.

The cap 14 and the container 10 have cooperating child-resistant locking means which consist of a radially outwardly directed tab 20 at the lower edge of the cap skirt 15 and a pair of stops 21 and 22 formed on the shoulder 13 of the container to be engaged by the tab 20. When the cap 14 is turned onto the container 10, either in its initial capping or after use, the cap 14 must be rotated a sufficient distance for the tab 20 to ride up an incline 23 on the shoulder 13 of the container 10 and then to snap by its own resiliency downwardly behind the stop 21. This is the closed position of the closure 14 relative to the container neck 12. The second stop 22 is angularly spaced beyond the first stop 21 only a distance sufficient that the tab 20 will drop down between the stops 21 and 22 and thus prevent the cap 14 from being turned angularly beyond this normal closed position.

If it were possible to manufacture the cap 14 and the container 10 and its threaded neck 12 without any tolerances in the dimensions, the cap 10 and the neck 12 could be maintained at proper sizes so that when the cap 10 is turned to the normal closed position, the liner 19 is pressed against the open neck 11 with just sufficient force so as to seal the container. Of course all manufactures on a production basis must be made with a definite manufacturing tolerance, say plus or minus 0.005 inch or the like, so that when these tolerances cumulate if the cap 10 is turned to its normal closed position, the liner 19 may or may not be in its proper sealing adjacency to the end of the container neck 12. If the tolerances cumulate in one direction, the container may not be sealed at all. If the tolerances cumulate in another direction, it may not be possible to turn the cap 14 far enough down onto the neck 12 for the child-resistant locking means comprising the tab 20 and the stop 21 to engage.

If it were economically feasible to utilize natural cork for the liner 19, it would have sufficient resiliency and compressability so that it could be made thick enough to engage the end of the container neck 12 in sealing relationship at both extremes of the tolerance variations. However, as mentioned above, the cost of cork has become prohibitive for its use as a liner in large volume containers such as aspirin bottles, and the like.

In order to compensate for the tolerance variations, the cap 14 of the invention has the annular shoulder portion 17 so that the liner 19 is brought into sealing engagement with the end of the threaded neck 12 of the container 10 whether the tolerances result in the locking tab 21 reaching the normal position as illustrated in FIG. 2 or as illustrated in FIG. 5. It will be observed by comparing the indicated distances d.sub.1 and d.sub.2, that the extremes of the tolerance variations are illustrated and that in both conditions, the tab 20 is positioned between the stops 21 and 22 and the liner 19 is pressed against the end of the neck 12. The annular shoulder 17 is illustrated as being stretched downwardly in FIG. 5 to compensate for the tolerance variations presumed to exist between the cap 14 and neck 12 of FIGS. 2 and 5, respectively.

Claims

Having described my invention, I claim:

1. A substantially leak-proof and child-resistant closure combination, said combination comprising

a. a container having a tubular neck, a hollow body and a generally inwardly extending shoulder between the upper portion of said body and the base of said neck,

b. a one-piece cap for said container, said cap having a tubular skirt, a disc-like top and a resilient annular shoulder portion means connecting said skirt and said top,

c. a disc-like liner beneath said cap top and engageable with the end of said container neck for sealing said neck,

d. means comprising mating threads on said neck and said cap skirt for retaining said cap on said neck,

e. and cooperating locking means on said cap skirt and said container shoulder engageable when said cap is rotated to normal closed position relative to said neck and for preventing rotation beyond normal closed position

f. said shoulder portion means being stretchable for downward movement of said tubular skirt for compensating for tolerance variations in said threads, and between said threads and said locking means.

2. A combination according to claim 1 in which the cooperating child-resistant locking means comprise a tab on the lower edge of the cap skirt and a pair of angularly spaced stops on the shoulder of the container engageable by said tab.