GB2260534A

GB2260534A - Child-resistant closures for containers

Info

Publication number: GB2260534A
Application number: GB9120264A
Authority: GB
Inventors: Roger Milner King
Original assignee: Beeson and Sons Ltd
Current assignee: Beeson and Sons Ltd
Priority date: 1991-09-23
Filing date: 1991-09-23
Publication date: 1993-04-21
Anticipated expiration: 2011-09-23
Also published as: GB2260534B; PL169520B1; GB9120264D0

Abstract

A child-resistant closure comprises an inner closure part (50) which is rotatable and axially movable in an outer closure part (10). Leaf springs (24), ratchet ramps (64) and engagable castellations (22, 60) on the closure parts allow the closure to be screwed down easily, but require the outer part to be depressed axially to enable the closure to be unscrewed. The leaf springs also bias the outer closure part rotationally away from each angular position in which it can be depressed. At no time can the closure be left in a condition which would allow the outer closure part to be depressed immediately. The leaf springs have cross-sections tapering towards their free ends, and are radiused at the acute angle with the outer closure part. There are sixteen castellations on each closure part so that the closure does not have to be rotated through more than 22.5 DEG before it can be depressed. The closure and the container neck have four-start, fully engaging square-section threads. Once depressed, the closure can be unscrewed by rotation through about 90 DEG or less. <IMAGE>

Description

IMPROVEMENTS IN CLOSURES FOR CONTAINERS The invention relates to closures for containers.

In this specification, a so-called "child-resistant" closure (hereinafter referred to as a "relevant childresistant closure") comprises an inner closure part adapted to be engaged with the neck of a container by rotation in one sense and to be disengaged therefrom by rotation in the other sense; an outer closure part capable of being moved relative to the inner closure part between a predetermined rest position and a displaced position; means to rotate the inner closure part with the outer closure part on rotation of the latter in the said one sense when the outer closure part is in either of its rest position and its displaced position; and means to rotate the inner closure part with the outer closure part on rotation of the latter in the said other sense when the outer closure part is in its displaced position, but when the outer closure part is in its rest position only when any torque resisting rotation of the inner closure part is below a predetermined threshold; wherein the outer closure part is capable of adopting its displaced position only when its angular displacement with respect to the inner closure part is within any one of a number of predetermined discrete angular ranges.

It will be appreciated that the term "discrete angular ranges" covers the case where the ranges are zero, and the outer closure part can adopt its displaced position only at discrete angles relative to the inner closure part.

The closure according to the invention is particularly suitable for use in the arrangement described in our International Patent Application No. PCT/GB91/00850 and/or that described in our U.K. Patent Application No. 9114871.8.

Many known child-resistant closures include a plurality of equidistant ramps on the outer surface of a crown portion of the inner closure part which cooperate with a plurality of equidistant, resilient oblique blades extending inwardly from a crown portion of the outer closure part When viewed from the centre of the respective closure parts, the ramps have a right triangular section comprising a horizontal base, a vertical left side and a hypotenuse and the blades extend diagonally downward from the left towards a lower right free end.

When the outer closure part is rotated clockwise, i.e. in a right-handed sense, the free ends of the blades abut the vertical faces of the ramps, thereby driving the inner closure part with the outer closure part.

When rotation of the outer closure part is effected in the other, left-handed sense, i.e. anticlockwise, the blades simply trail over the ramps in the manner of a ratchet, the inner closure part being fixed on the container by its closure torque.

Typically, castellations are provided on both inner and outer closure parts which mate when the outer closure part is depressed. The inner closure part is then bound to rotate with the outer closure part. When the outer closure part is released, the blades act as leaf springs to return it to its rest position, in which the castellations are disengaged.

Child-resistant closure systems normally rely on the ability of the closure to spring apart, every time, after pressure has been applied, generally at right angles to the plane of the thread. If, even on rare occasions the two parts of the closure do not spring apart and disengage, the child-resistant feature of the closure no longer functions. It is therefore essential that the blades acting as leaf springs have and continue to retain sufficient resilience to exert sufficient pressure to force the two parts of the closure apart in order that there is disengagement at all times, apart from occasions when direct and sufficient pressure is applied to engage the closure system.The main failure of existing systems to work properly at all times is due to the weakness of the leaf springs which in the past have typically been made of uniform thickness, with a sharp angle on the inside edge where the leaf spring joins the flat face of the underside of the top part of the closure.

This design is potentially unsatisfactory as the leaf springs can weaken at the point of joining the flat plane of the underside of the top part of the closure, and the leaves themselves tend to be stiff and as a result do not flex along the length of the spring leaf. To overcome this problem and to ensure more flexibility and to ensure that the leaf springs retain their resilience and hence the ability to force the two parts of the closure apart, and also to ensure that when being closed the planes of the top and lower part of the closure remain in parallel planes, the invention provides a relevant child-resistant closure comprising a plurality of cantilever leaf springs extending obliquely from one part of the closure towards the other part of the closure, each cantilever leaf spring having a cross-section which tapers towards its free end, and the profile at the acute angle between each cantilever leaf spring and the closure part from which said spring extends is radiused.

Another problem arises where a closure is primarily intended for use by the elderly, and hence must be easy to open, but which, for safety, must be child-resistant.

The number of castellations provided on known child-resistant closures is normally two, three or four, but this can require the closure to be rotated for up to 1800 before engagement of the castellations can take place. Engagement after a much smaller rotation is desirable, and according to a further aspect of the invention there is provided a container neck and closure therefor wherein the closure moves from fully closed to a fully open position by relative rotation through less than 3600, preferably approximately 900 or less, the closure being a relevant child-resistant closure and the number of said predetermined discrete angular ranges being such that angular displacement of the outer closure member relative to the inner closure member between adjacent positions in which the outer closure member can move to its displaced position is not greater than 450, and preferably not greater than 250. A preferred angular displacement is 22.5 , in which case, from a normal rest position, the outer closure would move to a position where it could be moved with its displaced position by rotation through 12.250 relative to the inner closure member. This preferred arrangement is provided by the closure having sixteen castellations, in which the maximum turn required for engagement is only one sixteenth, i.e. 22.50. This is an important feature when used in conjunction with the container and closure of our International Patent Application No. PCT/GB91/00850, where, in the preferred embodiment, the closure can be removed in only a quarter turn, and the addition of the child-resistant feature does not reduce the capacity to open the closure in approximately a quarter turn. This aspect particularly assists and supports ease of opening for the elderly and frail with only a twist of the wrists, without the necessity to let go of the closure of the container, even though being child-resistant.

The number of ramps in known closures varies, but is commonly three, four or six. The number of blades should be greater than two for stability, and should be a factor of the number of ramps.

In the past it has been arranged that the discrete angular ranges of angular displacement of the closure parts at which the castellations may engage one another is one in which the free ends of the blades on the outer closure part lie between ramps on the inner closure part.

A result of this is that it is perfectly possible for a container on which such a closure is installed to be left with the closure parts so oriented that the castellations may be engaged simply by immediate depression of the outer closure part. Such a situation can occur where a closure has been installed with the outer closure part depressed, or where an adult has depressed the outer closure part, but then changed his mind about removing the closure.

The present invention seeks to overcome the above problem and according to a further aspect of the invention provides a relevant child-resistant closure comprising means for biassing rotationally the outer closure part relative to the inner closure part from each angular displacement at which the outer closure part can adopt its displaced position to a respective angular displacement at which the outer closure part cannot adopt its displaced position. Preferably, the rotational biassing means exert a torque which is greater in absolute value than any frictional torque resisting relative rotation of the closure parts.

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

In the case where the friction between closure parts is sufficient to resist the restoring torque, enabling the closure to be left in a "primed" condition as it were, an advantage still obtains. Subsequent handling of the closure or the container to which the closure is attached, such as setting the container down, dropping it, picking it up, casting it into a "medicine box", will in most cases be sufficient to cause the outer closure part to move somewhat relative to the inner closure part. The outer closure part will then come to rest nearer to, if not actually at, the said respective angular displacement.

It is therefore extremely difficult, in normal usage, to leave the closure in a "primed" condition.

Preferably, the means to rotate the inner closure part with the outer closure part comprises a ratchet mechanism which restricts rotation of the outer closure part relative to the inner closure part in the said one sense, but permits such rotation in the said other sense.

Preferably, the rotational biassing means comprises the ratchet mechanism.

Preferably, the number of the said discrete angular ranges is equal to the number of stable positions of the ratchet mechanism. When the closure is for use in an arrangement as disclosed in our International Patent Application No. PCt/GB91/00850, it is advantageous for the number of the said discrete angular ranges to be at least eight, preferably sixteen.

This preserves the ability of the closure to be removed with a relatively small amount of rotation.

According to a further aspect of the invention, there is provided a container and closure as claimed in PCT/GB91/00850 or according to the invention of this application wherein the container neck and the container closure have fully engaging thread profiles to prevent play between the container and closure and ensure axial movement of the closure on the container. The threads may be of square section, rather than conventional "V" section threads to provide maximum stability when the threads first engage, and increasingly thereafter, whereby in conjunction with the four threads as described in our Patent Application No. PCT/GB91/00850, the square section thread ensures that the closure is pushed, wound down to its closed position on a parallel plane, thereby making it easier for the engagement of the child-resistant closure in one simple turn of the wrist.

The same applies when opening.

For increased security, it is preferred that one of the closure parts be provided with a tamper-evident ring.

A preferred embodiment of a closure according to the present invention will now be described with reference to Figures 1 to 8 of the accompanying drawings, in which: Figure 1 is a longitudinal sectional view of the outer closure part of the closure; Figure 2 is an underneath view of the outer closure part of Figure 1; Figure 3 is a plan view of the inner closure part of the closure; Figure 4 is an underneath view of the inner closure part of Figure 3; Figure 5 is a longitudinal sectional view of the inner closure part of Figures 3 and 4; Figure 6 is a side view of the inner closure part of Figures 3 to 5; Figure 7 is a longitudinal sectional view of the assembled closure retained on a container neck; and Figure 8 is a side view showing the profile of a blade in the form of a leaf spring.

As can be seen from Figure 1, an outer closure part 10, constructed of moulded plastics (other suitable materials may be used), consists of a crown portion 12 and a skirt portion 14. The crown portion is provided on its outer surface with a diametric handle 16. The particular form of handle shown includes a central opening 18. Towards the lower, free end of the skirt portion 14, there is provided an inwardly extending bead 20, whose purpose is to retain the outer closure part on the inner closure part as will be described below.

Both Figures 1 and 2 illustrate that the inner surface of the crown portion 12 is provided with sixteen equidistant castellations 22 of substantially rectangular form and four equidistant oblique resilient blades 24.

The resilient blades 24 extend circumferentially from an upper, left-hand end 26, when viewed from the centre of the closure part, to a lower, right-hand free end 28.

As can be seen from Figures 3 to 6, an inner closure part 50, constructed of moulded plastics (other suitable materials may be used), which includes a crown portion 52 and a skirt portion 54. The inner surface of the skirt portion 54 is provided with coarsely pitched threads 56 of square section 56 and vertical ribs 58, the function and purpose of which are described in detail in our International Patent Application No. PCT/GB91/00850. The top of the skirt portion 54 is provided with a tapered surface, the function and purpose of which are described in detail in our U.K.

Patent Application No. 9114871.8.

Depending from the lower end of the inner closure part skirt portion 54 is a tamper-evident ring 70 which will be described below.

The crown portion 52 is provided around its periphery with sixteen upstanding, substantially rectangular castellations 60. These castellations 60 are adapted to engage the complementary castellations 22 on the outer closure part (see Figure 2) 10. The outer periphery of the skirt portion 54 includes an outstanding ridge 62 below which, when the inner 50 and outer 10 closure parts are assembled, the bead 20 on the outer closure part 10 is retained. A degree of axial movement of the outer closure part 10 with respect to the inner closure part is permitted to engage and disengage the two sets of castellations 60, 22.

Partly shown in Figure 5, but fully in Figure 3, are sixteen equidistant ramps 64, provided on the upper surface of the inner closure part crown portion 52.

When viewed from the centre of the closure part, each ramp 64 is of substantially right triangular section having a horizontal base, a vertical left-hand side 66 and a hypotenuse, terminating in a right-hand side 68.

When the outer closure part 10 is installed on the inner closure part 50, and the outer closure part 10 rotated clockwise, the free ends 28 of the resilient blades 24 abut against the vertical side 66 of their respective ramps, thus rotating the inner closure part 50 with the outer closure part 10. However, assuming that the inner closure part 50 is reasonably tightly held in place, e.g. by a closure torque, then rotation of the outer closure part 10 anticlockwise will merely result in the resilient blades 24 trailing over the ramps 64 in the manner of a ratchet mechanism.

In order for the inner closure part 50 to be rotated anticlockwise, it is necessary for the outer closure part 10 to be depressed against the action of the resilient blades 24 to allow the complementary castellations 22, 60 to engage.

The handle 16 enables the elderly and frail more easily to apply the force required to push down and engage the two parts of the closure, whilst at the same time the handle 16 makes it easy to turn the closure to open it. When closing the same principles and advantages apply. The handle 16 therefore makes the closure much easier to operate, in spite of the childresistant feature, compared with standard child-resistant closures which many people, not just children find difficult to open.

Alternatively, the handle 16 may be substituted by four side flanges to the outer closure part 10 which again enables easier opening and closing, or a standard cap with ribbed outer edges.

The relative angular displacements at which the complementary castellations 22, 60 may be engaged correspond to positions in which the free ends 28 of the resilient blades 24 have already travelled some distance along and up their respective ramps 64. They therefore correspond to positions of increased potential energy.

The resilience of the blades 24 is such that, when the outer closure part 10 is released in such a displacement, the free ends 28 of the blades tend to move back down the sloping surfaces of the ramps 64 to their right hand sides 68. Once this has occurred, the complementary castellations 60, 22 are no longer so oriented as to be immediately engageable with one another.

Thus, all the rotationally stable positions of the outer closure part 10 with respect to the inner closure part 50 correspond to orientations of the castellations 22, 60 in which they cannot immediately be engaged only by depression of the outer closure part 10.

The tamper-evident ring 70 carried by the inner closure part 50 is shown in detail in Figures 4 to 6.

Attached to the top of the ring and integral therewith are eight connecting members 72 which taper upwards from a relatively thick lower region into a relatively thin frangible bridge 74 attached to the inner closure part skirt portion 54. On the inside of the tamper-evident ring 70, extending between the connecting members are eight triangular section ring retaining clips 76 which are adapted to engage a circumferential projection on the outer surface of a container neck.

The assembled closure is shown in Figure 7, and specific details of the thread 56 and vertical rib 58 and the seal between closure and container 100 may be found in our two Patent specifications cited herein. As can be seen in Figure 7, the thread is essentially square in section, providing positive and axial alignment of the two closure parts. The container 100 includes an outstanding circumferential projection 120 which is engaged by the ring retaining clips 76. Unscrewing the closure will result in the frangible bridges 74 being stretched and broken.

Figure 8 shows a preferred profile of a blade in the form of a leaf spring 24'.

As can be seen, the leaf spring 24' is thicker at its base, becoming progressively thinner towards its free edge 90. The joint of the leaf spring 24' with the remainder of the outer closure part 10 is radiused to provide extra strength. This profile gives sufficient resilience and strength to the leaf spring 24' to ensure that the outer closure part 10 and inner closure part 50 are always separated until axial pressure is applied to counteract the bias of the springs 24'.

An important advantage of this embodiment of the invention is that, in conjunction with features of the container and closure described in PCT/GB91/00850, this is the only child-resistant closure which opens in under half a turn, i.e. 1800, and more generally in approximately a quarter turn i.e. 90" or less, also in conjunction with the container of British Patent Application No. 9114871.8 it is the only child-resistant closure system which can be used in conjunction with either both a tamper-evident ring and a foil seal whereby the seal of the closure is air and liquid proof after the foil has been removed or broken.

This embodiment of the invention is by way of example only; modifications and alterations may be made within the scope of the invention.

Claims

1. A relevant child-resistant closure comprising means for biasing rotationally the outer closure part relative to the inner closure part from each angular disposition at which the outer closure part can adopt its displaced position to a respective angular displacement at which the outer closure part cannot adopt its displaced position.

2. A closure according to claim 1 wherein biassing means exert a torque which is greater in absolute value than any frictional torque resisting relative rotation of the closure parts.

3. A closure according to claim 1 or 2 wherein at no time can the closure of the invention be left in a condition at which immediate axial movement of the outer closure part from its rest position to its displaced position is possible.

4. A closure according to claim 1, 2 or 3 wherein the means to rotate the inner closure part relative to the outer closure part comprises a ratchet mechanism which restricts rotation of the outer closure part relative to the inner closure part in said first one sense, but permits such rotation in the said other sense.

5. A closure according to claim 4 wherein the rotational biassing means comprises the ratchet mechanism

6. A container neck and closure therefor wherein the closure moves from fully closed to a fully open position by relative rotation through less than 3600, the closure being a relevant child-resistant closure and the number of said predetermined discrete angular ranges being such that angular displacement of the outer closure member relative to the inner closure member between adjacent positions in which the outer closure member can move to its displaced position is not greater than 450.

7. A container neck and closure therefor according to claim 1, wherein the closure moves from a fully closed to a fully open position by relative rotation of about 900 or less.

8. A container neck and closure therefor according to claim 6 or 7 wherein said angular displacement is not greater than 250.

9. A container neck and closure therefor according to claim 8, wherein said angular displacement is 22.50.

10. A container neck and closure therefor according to claim 9, including castellations on the inner and outer closure parts, which castellations mate when the outer part is depressed, the closure having sixteen said castellations.

11. A relevant child-resistant closure comprising a plurality of cantilever leaf springs extending obliquely from one part of the closure towards the other part of the closure, each cantilever leaf spring having a cross-section which tapers towards its free end, and the profile at the acute angle between each cantilever leaf spring and the closure part from which said spring extends being radiused.

12. A container and closure therefor, wherein the container neck and the container closure have fully engaging thread profiles to prevent play between the container and closure and ensure axial movement of the closure on the container.

13. A container and closure therefor according to claim 12, wherein the threads are of square section, to provide maximum stability when the threads first engage and increasingly thereafter.

14. A container and closure therefor according to claim 12 or 13, comprising four thread starts.

15. A container and closure therefor as claimed in claim 12, 13, or 14, wherein the closure is a relevant child resistant closure.

16. A container and closure therefor according to any of claims 12 to 15, wherein the closure is fitted with a tamper-evident ring.

17. A container and closure according to any of claims 12 to 16, wherein the closure moves from a fully closed to a fully open position on the container neck by relative rotation through about 900 or less.