DE69232244T2 - Childproof tamper-evident closure - Google Patents

Description

The present invention relates to an improved child-resistant container closure assembly.

Prior art relating to child-resistant container closure assemblies is described in US-A-3894647, US-A-4213534, US-A-3770153, US-A-3944101, US-A-3831797, and WO-A-9004546.

US-A-3944101 describes a child-resistant container closure assembly according to the preamble of claim 1 and further comprises a sealing ring attached to the container closure.

Many known child-resistant closures include a plurality of equally spaced ramps on an outer surface of a head portion of an inner closure member cooperating with a plurality of equally spaced resilient inclined leaves extending inwardly from a head portion of an outer closure member. When viewed from the center of the respective closure members, the ramps have a precisely triangular section comprising a horizontal base, a vertical left side and a hypotenuse, and the leaves extend diagonally downwardly from the left toward a lower right free end.

When the outer shutter part is rotated clockwise, i.e. right-handed, the free ends of the blades rest against the vertical surfaces of the ramps, driving the inner shutter part with the outer shutter part.

If the rotation of the outer shutter part is in the other, left-handed direction, i.e. counterclockwise, the blades simply grind over the Ramps in the manner of a locking hook, whereby the inner locking part is fixed on the container by its locking torque.

Typically, teeth are provided on both the inner and outer locking members that engage when the outer locking member is depressed. The inner locking member is then forced to rotate with the outer locking member. When the outer locking member is released, the leaves act as leaf springs to return it to its rest position where the teeth no longer engage.

Child-resistant locking systems normally rely on the ability of the locking mechanism to spring apart each time pressure is applied, generally at a right angle to the plane of the thread. If, albeit in rare cases, the two parts of the locking mechanism do not spring apart and separate, the child-resistant feature of the locking mechanism will no longer function. It is therefore essential that the leaves acting as leaf springs have and are maintained sufficient elasticity to exert sufficient pressure to force the two parts of the locking mechanism apart so that it never engages except in cases where direct and sufficient pressure is applied to engage the locking mechanism. The main flaw in existing systems, as they are designed to operate cleanly at all times, lies in the weakness of leaf springs, which in the past have typically been manufactured in uniform thickness with a sharp angle on the inside edge where the leaf spring meets the flat surface of the underside of the top of the locking mechanism. This design can be unsatisfactory because the leaf springs can be weakened at the point of connection of the flat plane of the bottom of the top of the closure, and the leaves themselves tend to become stiff and as a result no longer flex along the length of the leaf spring.

Another problem arises where a fastener is primarily intended for use by older people and therefore needs to be easy to open, but needs to be child-resistant for safety.

The number of teeth provided on common child-resistant fasteners is usually 2, 3 or 4, but this may require the fastener to be rotated up to 180º before the teeth engage. Locking after much smaller rotation is desirable.

A further disadvantage of earlier child-resistant locking arrangements was that the individual angular ranges of angular displacement of the locking parts at which the teeth can engage with each other are those in which the free ends of the leaves on the outer locking part lie between the ramps on the inner locking part.

A result of this is that it is quite possible for a container on which such a closure is installed to be oriented with the closure parts in such a way that the teeth are engaged simply by immediately depressing the outer closure part. Such a situation may arise where a closure has been installed with the outer closure part depressed or where an adult has depressed the outer closure part but then has changed his mind about removing the closure.

Accordingly, it is the object of the present invention to address one or more of the above-mentioned disadvantages of existing child-resistant closure assemblies of this general type.

The present invention provides a child resistant container closure assembly as defined in claim 1 of the appended claims.

Preferably, the closure is movable from a fully closed position on the neck to a fully released position by rotation through 360º or less, preferably 180º or less, and more preferably approximately 90º or less. Preferably, the first and second threads on the container neck and the closure have fully engaging thread profiles to prevent play between the container and the closure and to ensure axial movement of the closure on the container. Preferably, the first and second threads have a square or rectangular cross-section to provide maximum stability when the threads first engage and even more so thereafter. This arrangement is preferred over the conventional "V" cross-section threads. The square cross-section thread ensures that the closure is turned down to its closed position on a parallel plane, allowing for the child-resistant closure to be secured with a simple turn of the wrist. The same applies to opening. Preferably either the first or second thread has four threads.

Preferably, one of the closure parts is provided with a sealing ring. For example, the sealing ring can be provided on the inner closure part. A child-resistant closure has not previously been provided with a sealing ring because of the difficulty of opening using conventional child safety systems.

The first and second retaining means may comprise one or more projections on the container neck for engaging one or more projections in the closure. The projections may sequentially "click" as the closure is rotated to or from its fully closed position. Preferably, the first retaining means comprises stopper elements on the neck or closure and the second retaining means comprises one or more ribs or projections on the closure or neck for engaging the stopper elements. At least one of the projections may be profiled to comprise a peripheral ramp surface on which the other projections can slide relatively easily as the closure approaches the closure position and a relatively steep or radial abutment surface against which the other projections bear when the closure is to be unscrewed from the closed position.

Preferably, the child-resistant container closure assembly according to the present invention further comprises an upstanding flange handle on the outer closure member. In an alternative embodiment, side flanges may be provided on the handle to assist in the application of torque when opening the closure. Preferably, the closure and the Container neck as defined in our international patent application WO91/18799.

Preferably, the angular displacement of the outer closure member relative to the inner closure member between adjacent positions at which the outer closure member can be moved to its remote position to engage the first and second sets of teeth is not greater than 45°, and preferably not greater than 25°. A particularly preferred angular displacement is 22.5°, in which case, from a normal rest position, the outer closure would be moved to a position where it could actually be moved to its remote position by rotation through 12.25° relative to the inner closure member. This preferred arrangement is provided by the 16 tooth closure in which the maximum rotation required for fastening is only 1/16, i.e. 22.5°. This aspect particularly helps and supports the ease of opening for the elderly and infirm with just a twist of the wrist, without the need to let go of the cap or the container, while remaining childproof.

Preferably, at least one of the first and second sets of teeth has at least 8 equiangularly spaced teeth and preferably 16 equiangularly spaced teeth. Preferably 16 of the locking ramp projections are on the inner or outer closure part. The number of resilient leaves (projecting leaf spring) should be greater than 2 for stability and should be a factor of the number of locking ramp projections.

Preferably, the child resistant container closure assembly according to the present invention comprises means for rotationally biasing (urging) the outer closure member relative to the inner closure member from any angular displacement at which the outer closure member can adjust its axially displaced position at which the teeth engage, to a corresponding angular displacement at which the outer closure member cannot adjust its axially displaced position.

Preferably this is accomplished by arranging the locking ramp projections relative to the resilient leaves (projecting leaf springs) and the first and second sets of teeth, when the teeth are arranged relative to each other so that they can be brought into engagement with each other by axial displacement of the outer closure member, the resilient leaves bearing on those edge surfaces of the locking projections to apply a rotational force between the inner and outer members to urge the outer member out of the aligned orientation and into a much more aligned orientation of the teeth.

Preferably, the rotational force between the inner and outer parts is greater in absolute value than any frictional torque resisting the relative rotation of the closure parts.

In this preferred case, at no time can the closure of the invention be left in a condition in which intermediate movement of the outer closure part from its rest position to a remote position is possible. The outer closure part must first be rotated against a residual force before such displacement can be effected.

In the case where the friction between the closure members is sufficient to resist the rotational force, allowing the closure to be left in a "ready-to-use" condition as it was, an advantage is still obtained. Subsequent handling of the closure or the container to which the closure is attached, as well as setting the container down, dropping it, picking it up, or throwing it into a "medicine box" will in most cases be sufficient to cause the outer closure member to move slightly relative to the inner closure member. The outer closure member will then rest in a rest position close to, if not exactly, an angular displacement at which the teeth are out of alignment.

It is therefore very difficult to keep the shutter in a "ready-to-use" state during normal use.

Preferably, each resilient leaf has a cross-section that tapers towards its free end and the profile at the acute angle between each resilient leaf and the closure part from which the leaf projects is wedge-shaped. This helps to ensure that the resilient leaves retain their resilience and therefore the ability to push the two parts away from the closure and also to ensure that the planes of the upper and lower parts of the closure remain in parallel planes when closed.

A specific embodiment of the present invention will now be further described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal cross-sectional view of an outer closure part of a child-resistant closure assembly according to the invention;

Fig. 2 is a bottom view of the outer closure member of Fig. 1;

Fig. 3 is a top plan view of the corresponding inner closure part of the child-resistant closure assembly;

Fig. 4 is a bottom view of the inner closure member of Fig. 3;

Fig. 5 is a longitudinal cross-sectional view of the inner closure member of Figs. 3 and 4 (unsectioned portions of the ramps 364 have been omitted for clarity);

Fig. 6 is an exploded side view of the inner closure member of Figs. 3 to 5;

Fig. 7 is a partially longitudinal cross-sectional view of the closure assembly with the closure remaining on the container neck; and Fig. 8 is a side view showing the profile of an elastic sheet in the form of a leaf spring.

Referring to Fig. 1, an outer closure member 310 constructed of molded plastic (other suitable materials may be used) consists of a head member 312 and a shell member 314. The head member is provided with a diametrical handle 316 on its outer surface. The particular shape of the handle shown includes a central opening 318. Towards the lower free end of the shell member 314 there is provided an inwardly projecting bead 320, the purpose of which is to retain the outer closure member on the inner closure member, as will be described below.

1 and 2 illustrate that the inner surface of the head portion 312 is provided with 16 equally spaced teeth 322 of substantially rectangular shape and with 4 equally spaced oblique elastic leaves 324. The elastic leaves 324 extend circumferentially from an upper left-hand end 326, as viewed from the center of the closure portion, to a lower right-hand free end 328.

In Figures 3 to 6 there can be seen an inner closure member 350 constructed of molded plastic (other suitable materials may be used) which includes a head portion 352 and a skirt portion 354. The inner surface of the skirt portion 354 is provided with highly inclined threads 356 of square cross section with vertical lobes 358, the function and purpose of which are described in detail by our international patent application WO91/18799, published on 12.12.91. The top of the skirt portion 354 is provided with a conical sealing surface.

Depending on the lower end of the inner closure portion, the skirt portion 354 is a sealing ring 370, which is described below.

The head portion 352 is provided around its periphery with 16 upstanding, substantially rectangular teeth 360. These teeth 360 are adapted to fit into the complementary teeth 322 on the outer closure portion (see Fig. 2). 310. The outer periphery of the shell portion 354 includes an outwardly projecting bead 243 under which, when the inner 350 and outer 310 closure members are assembled, the bead 320 is retained on the outer closure member 310. A degree of axial movement of the outer closure member 310 with respect to the inner closure member is permitted to engage and disengage the two sets of teeth 360, 322.

Partially shown in Fig. 5, but fully shown in Fig. 3, are 16 equally spaced ramps 364 provided on the upper surface of the head portion 352 of the inner closure member. Viewed from the center of the closure member, each ramp 364 is of substantially rectangular cross-section having a horizontal base, a vertical left side 366, and a hypotenuse terminating in a right side 368.

When the outer closure member 310 is installed on the inner closure member 350 and the outer closure member 310 is rotated clockwise, the free ends 328 of the elastic leaves 324 engage their corresponding ramps, causing the inner closure member 350 to rotate with the outer closure member 310. However, assuming that the inner closure member 350 is held fairly firmly in place, such as by a closure torque, counterclockwise rotation of the outer closure member 310 will merely result in the elastic leaves 324 dragging over the ramps 364 in the manner of a locking mechanism.

In order to rotate the inner closure part 350 counterclockwise, it is necessary for the outer closure part 310 to be pressed down against the action of the elastic leaves 324 to allow the complementary teeth 322, 360 to mesh.

The handle 316 enables the elderly and infirm to more easily apply the force required to push down and lock the two parts of the closure, while at the same time the handle 316 makes it easier to rotate the closure to open it. When closing, the same principles and advantages apply. The handle 316 therefore makes handling the closure much easier, notwithstanding the child-resistant feature, compared to standard child-resistant closures which many people, not just children, find difficult to open. Alternatively, the handle 316 may be supported by four side flanges on the outer closure part 310, again allowing easier opening and closing, or with a standard cap with serrated outer edges.

The relative angular displacements at which the complementary teeth 322, 360 can engage correspond to the positions in which the free ends 328 of the elastic leaves 324 have already traveled some distance along and up their respective ramps 364. They therefore correspond to the positions of increased potential energy. The elasticity of the leaves 324 is such that when the outer closure part 310 is released in such a displacement, the free ends 328 of the leaves tend to move the inclined surfaces of the ramps 364 back to their right side 368. Once this has occurred, the complementary teeth 360, 322 are no longer oriented to be immediately engageable with one another.

Therefore, all rotationally stable positions of the outer closure part 310 with respect to the inner closure part 350 correspond to such orientations of the teeth 322, 360 in which they cannot immediately engage with one another by pressing down the outer closure part 310.

The sealing ring 370 carried by the inner closure member 350 is shown in detail in Fig. 4-6. Attached to the top of the ring and integrally thereto are 8 connecting elements 372 which taper upwardly from a relatively thick lower region into a relatively thin frangible bridge 374, the bridge being attached to the skirt portion 354 of the inner closure member. On the inside of the sealing ring 370 extending between the connecting elements are 8 triangular section ring retaining clips 376 which are adapted to snap into a circumferential projection on the outer surface of a container neck.

The assembled closure is shown in Fig. 7 and specific details of the thread 356 and vertical ribs 358 and the seal between the closure and the container 390 can be found in WO91/18799. As can be seen in Figure 7, the thread is substantially square in cross-section, thereby providing positive and axial alignment of the two closure parts. The container 390 includes an outwardly projecting circumferential projection 392 which is retained by the ring retaining clips 376. Unscrewing the closure will cause the frangible bridges 374 to be stretched and broken.

Fig. 8 shows a preferred profile of a leaf in the form of a leaf spring 324'.

As can be seen, the leaf spring 324' is thicker at its base, progressively thinning towards its free end 394. The junction of the leaf spring 324' to the rest of the outer closure portion 310 is rounded to provide additional strength. This profile provides the leaf spring 324' with enough resilience and strength to ensure that the outer closure portion 310 and the inner closure portion 350 are always separated until axial pressure is applied to counteract the preload of the springs 324'.

An important advantage of this embodiment of the invention is that, in conjunction with the features of the container and closure described in WO91/18799, this is the only child-resistant closure which opens with a half turn, i.e. 180º and generally approximately a quarter turn, i.e. 90º or less, thus it is the only child-resistant closure system which can be used in conjunction with a sealing ring and/or a foil seal, the seal of the closure being air and liquid tight after removal or rupture of the foil.

This closure system has the advantage when closing the closure system that the closure is held on the container in such a way that the child-resistant closure mechanism works effectively, but that the closure can be released as soon as the outer part of the closure is moved to the removed position by applying a calculable torque. Conventional child-resistant spring leaf closures are screwed onto a neck thread with more than 360º rotation to the closure. For all conventional child-resistant Spring leaf systems require that they be screwed on very tightly when closing, otherwise the child resistant system will not be effective and therefore the purpose of the child resistant system will not be achieved. The weakness of conventional child resistant systems is therefore obvious as arthritic, infirm and elderly users are not able to close such containers tightly enough either to seal them properly or even, if they have been tightly sealed by someone else, to open them. This invention solves the problems of conventional child resistant closures by tightening the closure sufficiently in that the closure does not need to be tightly closed for the child resistant system to be effective and is therefore particularly effective for arthritic, infirm and elderly users. This new closure system enables containers and bottles to be easily opened and closed in approximately a quarter turn with an effective child resistant system.

Claims (13)

1. A child-resistant container closure assembly comprising a container neck and a closure, the container neck carrying a first screw thread and the container closure comprising: an inner member (350) and an outer member (310), the outer member (310) being retained on the inner member (350) and capable of limited axial movement on the inner member (350) between a rest position and a displaced position ; wherein the inner part (350) carries a second screw thread for screw thread connection with the first screw thread of the container neck piece; a first set of teeth (360) on the inner part (350); a second set of teeth (322) disposed on the outer member (310) for engaging the first set of teeth (360) on the inner member (350) when the outer member (310) is in the offset position to apply the full torque to the inner member (350); a set of resilient leaves (324) extending from a first of the inner or outer members (350, 310) to a second of the inner or outer members (310, 350), the resilient leaves (324) bearing on the second of the inner and outer members (310, 350) to urge the outer member (310) axially in a direction away from the inner member (350) such that the outer member is normally held in the rest position with the first and second sets of teeth (322, 360) disengaged from each other; the second of the inner and outer members (310, 350) comprising a set of locking ramp projections (364), each of the locking ramp projections (364) being constructed and arranged to engage one of the resilient leaves (324) when the outer member (310) is rotated to the closed position to attach the closure to the neck piece to thereby to allow the full torque to act on the inner part (350) in the closing direction; wherein each of the locking ramp projections (364) is constructed and arranged such that the resilient leaves (324) are enabled to slide over the locking ramp projections (364) when the closure member (310) is rotated in the opening direction opposite to the closing direction without the first and second sets of teeth (322, 360) engaging, whereby only a limited opening torque is transmitted from the outer closure member to the inner closure member through the resilient leaves (324) sliding over the locking ramp projections (364), characterized in that the container neck further carries first retention means and the inner part (350) of the closure further comprises a second retention means (358) for engaging the first retention means when the closure is screwed down to re-secure it to a closed position on the container neck, the first and second (358) retention means being constructed and arranged to resist release of the closure from the closed position until a predetermined release torque is applied to the inner part (350) in the second direction, which predetermined release torque is greater than the limited opening torque transmitted from the outer closure part (310) to the inner closure part (350) by the resilient leaves (324) sliding over the locking ramp projections (364), thereby reducing the risk of accidental opening of the device when the first and second sets of teeth (322, 360) are not engaged. 2. The child resistant container closure assembly of claim 1, wherein the closure is movable between the fully closed position and the position where the closure is fully disengaged from the neck by rotation of approximately 90 degrees or less. 3. A child-resistant container closure assembly according to claim 1 or 2, further comprising a sealing ring (370) attached to the closure. 4. A child-resistant container closure assembly according to claim 1, 2 or 3, wherein the first and second (356) threads comprise fully engaging thread profiles to prevent play between the container and the closure. and ensure axial movement of the closure on the container. 5. A child resistant container closure assembly according to claim 4, wherein the first and second (356) threads are of square or rectangular cross section. 6. A child-resistant container closure assembly according to any preceding claim, wherein the first retaining means comprises stopper elements on one of the neckpiece and the closure and the second retaining means comprises one or more slats or projections on one of the other of the closure and the neckpiece for engaging the stopper elements. 7. A child-resistant container closure assembly according to any preceding claim, further comprising an upstanding collar handle (316) extending from the closure member (310). 8. A child resistant container closure assembly according to any preceding claim, wherein the locking ramp surfaces and the resilient leaves are arranged to the first and second sets of teeth such that when the sets of teeth are aligned with each other so that they can be brought into engagement with each other, the resilient leaves load on these ramp surfaces of the locking projections to apply a rotational force between the inner and outer members to urge the outer member out of the aligned orientation, thereby urging the outer member out of the aligned orientation in which the teeth can be brought into engagement with each other. 9. A child resistant container closure assembly according to any preceding claim, wherein the first and second threads have four thread starts. 10. A child resistant container closure assembly according to any preceding claim, wherein each resilient leaf has a cross-section tapering towards its free end and the profile is curved at the acute angle between each resilient leaf and the closure member from which the leaf extends. 11. A child-resistant container closure assembly according to any preceding claim, wherein at least one of the first and second sets of teeth (322, 360) has at least eight angularly equally spaced teeth. 12. A child-resistant container closure assembly according to any preceding claim, wherein the angular offset of the outer closure member (310) relative to the inner member (350) between adjacent angular positions at which the outer closure member (310) can move toward the offset position is not greater than 45°. 13. A child resistant container closure assembly according to any preceding claim, wherein there are sixteen of said locking ramp projections (364).