A closure for a container

Abstract

 A child resistant closure (CRC) of the type having an inner cap (2) and an outer cap (4), the caps having between them an off-screwing drive mechanism which is strong, reliable and compact. The inner cap (2) is provided with a central projection (18), which may be hexagonal, and which engages a recess (32) in the outer cap, and ribs (20) which extend radially from the central projection on the inner cap. The recess is defined by a number of abutments (30) on the outer cap which also engage the driving ribs.

Description

[0001] This invention relates to a child resistant closure (CRC) of the type having an inner cap and an outer cap, the inner cap being of smaller dimensions than the outer cap and fitting inside same to form the closure.

[0002] Once such a closure is applied to a container by an on-screwing action, the container is again accessable only in the hands of a user who is able to apply axial pressure onto the closure whilst transmitting an off-screwing force thereto. Children are generally unable to combine these actions, and thus the container, which may contain potentially harmful medicines or chemicals, is rendered child resistant.

[0003] Closures of this type are well known, however existing closures generally lack durability and can be unreliable due to the failure or malfunctioning of the drive mechanisms between the caps, which can prevent removal of a closure from a container.

[0004] Due to the nature of the contents of a container which will be provided with a CRC, it is furthermore desirable to provide the CRC with a tampering indicator which shows when the off-screwing drive means has been actuated, and therefore that a first time consumer can tell whether the closure has been tampered with, in particular removal of the closure from the container.

[0005] There are however difficulties in the provision of a variety of co-operating formations between the inner and outer caps, including the delicacy, bulkiness and failure tendency of the drive mechanism, particularly when a further, on-screwing drive means is provided.

[0006] An attempt has been made to overcome these difficulties by the provision of a hexagonal spigot on the inner cap of a CRC, in combination with an orifice of corresponding shape on the outer cap. It has however been found that occasionally such a drive mechanism will fail as the corners of the hexagonal spigot are worn down through use. It is also possible, due to the near-circularity of the spigot outline, to cause the mechanism to lock if the outer cap is pushed down with force while the spigot and orifice are not properly aligned. The present invention seeks to alleviate the abovementioned problems, by the provision of a CRC which is both hard wearing, reliable and compact.

[0007] According to the present invention there is provided a closure for a container, comprising an inner cap and an outer cap, the inner cap being received and held within the outer cap by a retention means to form the closure and there being provided an off-screwing drive means between the caps, in which the caps are relatively displaceable against a biasing force provided by biasing means between the caps by means of manual pressure applied to the outer cap between a rest position wherein the outer cap is freely rotatable with respect to the inner cap when turned in an off-screwing direction, the said drive means being disengaged, and an active position at which the biasing force has been overcome and wherein the said drive means is engaged to allow the closure to be unscrewed from a container to which it is applied, the said drive means comprising:-

a) a central projection on one cap which engages a recess or orifice on the other cap, and

b) one or more ribs located around the central projection, which ribs are engaged by abutments on the other cap,

characterised in that the said rib-engaging abutments are arranged to at least partially define the said recess or orifice.

[0008] This arrangement allows for a tight interfitment between the caps' off-screwing drive mechanism counterparts, and the achievement of a strong and positive drive.

[0009] The said central projection and ribs are preferably interconnected to form a one-piece projection located on an end face surface of one of the caps. The said one-piece projection is preferably located on the outer surface of the inner cap.

[0010] The said ribs preferably interfit tightly between the said abutments on the other cap. In one embodiment, the central projection has a polygonal outline, and the said ribs preferably project radially from the centre of each polygonal face. In this embodiment, the said abutments are suitably V-shaped so as to drivingly interengage not only the abutments but also the corners of the polygonal outline. The ends of the V-shape will then abut against adjacent radial ribs.

[0011] The rib portions may extend further radially and co-operate with ratchet means positioned on the adjacent surface of the respective caps to provide a further off-screwing drive means which is engageable in the rest, or biased apart, position of the caps to drive the closure in an on-screwing direction only. These additional rib extensions may be stepped in height to ensure that whilst the ratchet means is reliably engaged at least by the highest such rib portions, the free rotation of the caps when the outer cap is turned in an off-screwing direction is mostly unhindered by the inclusion of lower such rib portions.

[0012] The inner cap preferably comprises a central cylindrical spigot which co-operates with a tamper indicator on the outer cap to evidence the first occasion on which the off-screwing drive means is engaged. This tamper indicator may be in the form of a central orifice in the outer cap initially closed by a cover portion connected to the body of the outer cap by frangible means or such like.

[0013] The present invention will now be described with reference to the accompanying diagrams, and it will be appreciated from the following description that the present invention provides for a highly advanced and compact arrangement of drives and tamper indication for a child resistant closure, and this arrangement is advantageous in that it provides for the construction of a durable and reliable closure. In the drawings:-

Fig 1 illustrates in perspective view the inner cap of a closure according to an embodiment of the invention;

Fig 2 shows in plan view the cap shown in Fig 1;

Fig 3 shows in side view the cap shown in Fig 1;

Fig 4 shows the cap in cross section along the line A-A in Fig 2;

Fig 5 shows in plan view the underside of the outer cap of a closure according to the same embodiment of the invention;

Fig 6 is a cross sectional view along the line B-B of the cap shown in Fig 5; and

Fig 7 shows in perspective view an inner cap of a closure according to a further embodiment of the invention.

[0014] With reference to Figures 1 to 4, there will be seen an inner cap 2 which may be formed of plastics material by an injection moulding technique, as is true of the outer cap 4 shown in Fig 5. The inner cap has various other features in addition to the basic cap form, these features being an inner screw thread 6 for engagement with the external screw thread of a container, not shown, a protruding rim 8 at the base of the depending skirt portion 10, a unitary lug formation 12 which projects concentrically from the top portion 14 of the cap, and a cylindrical spigot 16 which projects centrally from the top portion 14.

[0015] The unitary lug formation 12 comprises a central hexagonal portion 18, six inner radially extending portions 20 from which further extend the same number of outer radially extending portions 22. The hexagonal portion 18 and the inner radial lugs 20 project at equal height from the top 14, forming part of a primary drive. The outer radial lugs projects from the top 14 at two lower heights, the outer lugs 22 alternating in heights around the top 14. The outer cap comprises the features of a retention bead 24 on the inner edge of the cap 4, a displacement channel 26 running around the inner surface of the skirt portion 28 and above the retention bead 24, angled lug portions 30 of V-shaped outline depending from the inner surface of the top portion 32, regularly spaced having radial openings 34 between and concentrically positioned on the top 32 to form a hexagonal recess 32.

[0016] Six spring fingers 36 of arcuate outline depend at an angle from the inner surface of the top 32.

[0017] Also, a central and circular opening 38 is provided in the top 32. Although not shown in the drawings, this opening is in this preferred embodiment closed over by a break-away disc portion which is connected to the top 32 by frangible webs.

[0018] It will be appreciated that the inner cap 2 is designed to fit within the outer cap 4, and to this end the protruding rim 8 on the inner cap co-operates with the retention bead 24 on the outer cap to maintain this arrangement.

[0019] The inner cap is however axially displaceable within the outer cap against the biassing force of the spring fingers 36 which act against the top portion 14 of the inner cap 2. This displacement is limited by the height of the displacement channel 26, in which the protruding rim 8 moves. The caps are displaceable between a rest postion, wherein the spring fingers 36 act to bias the caps apart and the protruding rim 8 rests against the retention bead 24, and a fully engaged position, which is attainable only at a number of angular placements of the caps, wherein the angled lugs 30 of the outer cap inter engage with the unitary lug formation, around the corners of the hexagonal portion 18 and between the inner radial lugs 20. In this fully engaged postion the spigot 16 protrudes through the aperture 38.

[0020] The child resistant drive mechanism operates to allow the closure to be screwed onto a container without the application of axial pressure but by means of the unidirectional drive provided by the co-operating spring fingers 36 and the outer radial extensions 22 of the lug formation 12. In order to unscrew the closure from a container however it is necessary to engage the primary drive by the application of axial pressure, since in the rest position the spring fingers 36 are ratchet natured and ride over the outer lugs 22 when the outer cap is turned in an anti-clockwise direction in an attempt to unscrew the closure.

[0021] By the application of manual pressure onto the outer cap 4, the interfitment of the angled lugs 30 with the unitary lug 12 can be effected, if necessary after some slight angular adjustment to register their positions. In this fully operational position the closure can be turned in an anti-clockwise direction to unscrew the closure from a container. In this action, the driving force is transmitted by the set of radial drive faces 40 and also the set of polygonal drive faces 42 on the inner cap, which co-operate with corresponding drive faces 44 and 46 respectively on each angled lug 30. This combination of both the direct driving engagement provided by the radial drive faces 40 and 44 and the slanted driving engagement of the polygonal drive faces 42 and 46 is advantageous in that the direct driving engagement ensures a positive and reliable inter-engagement of the unitary lug formation 12 within the recess 32 and across the openings 34 whilst the slanted driving engagement increases resistance to wear of the driving mechanism, in that the driving force is spread along the length of the polygonal faces 42 and 46, so that less pressure is exerted on this part of the driving mechansim.

[0022] An alternative embodiment of inner cap 52 according to a further aspect of the invention is shown in Fig 7, and it will be appreciated that the polygonal central portion of the unitary lug 12 has become a portion of circular outline 56, however inner radial lug portions 54 and outer radial lug portions 58 still extend from the disc portion 56. Although in this embodiment the advantage of the hexagonal drive has been removed, this embodiment retains advantages over the existing CRC's. In effect, the inner lugs 54 co-operate with arcuate engagement lugs corresponding to the angled lugs 30 on the outer cap 4, to which the outer cap of the present embodiment is otherwise identical.

[0023] The relative positioning and lateral interconnection of the spigot 60, the inner radial lugs being part of the primary drive, and the outer radial lugs 58 being part of the unidirectional drive mechanism, makes for a highly compact tamper-evident CRC mechanism which is of improved strength. The compact nature of the construction is provided by the efficient radial positioning of the tamper indicator means and the two drive means respectively, whilst the improved strength is achieved not only by the immediate adjacency of the positioning of the features but by the lateral interconnection of each of these features, which are subject to differing forces and therefore can act to support each other.

[0024] It will be appreciated by a person skilled in the art that the invention is not limited to the combinations of features described in relation to the two particular embodiments described. Many combinations of features of the present invention are inventive in their own right. Enhancements, modifications and the use of equivalents are all considered to fall within the scope of the invention, providing its essential elements are retained.

Claims

1. A closure for a container, comprising an inner cap and an outer cap, the inner cap being received and held within the outer cap by a retention means to form the closure and there being provided an off-screwing drive means between the caps, in which the caps are relatively displacable against a biasing force provided by biasing means between the caps by means of manual pressure applied to the outer cap between a rest position, wherein the outer cap is freely rotatable with respect to the inner cap when turned in an off-screwing direction, the said drive means being disengaged, and an active position at which the biasing force has been overcome and wherein the said drive means is engaged to allow the closure to be unscrewed from a container to which it is applied, the said drive means comprising:-

a) a central projection on one cap which engages a recess or orifice on the other cap; and

b) one or more ribs located around the central projection which ribs are engaged by abutments on the other cap,

characterised in that the said rib-engaging abutments are arranged to at least partially define the said recess or orifice.

2. A closure according to claim 1 wherein the said central projection and said one or more ribs are connected to form a one-piece projection located on an end surface of one of the caps.

3. A closure according to claim 2 wherein the said one-piece projection is located on the outer surface of the inner cap.

4. A closure according to any of claims 1 to 3 wherein the central projection has a polygonal outline.

5. A closure according to claim 4 wherein the said ribs project radially from the centre of the polygonal faces of the central projection.

6. A closure according to claim 4 or 5 wherein the said abutments are V-shaped so as to drivingly interengage the corner portions of the polygonal central projection.

7. A closure according to any of claims 1 to 6 wherein the said ribs have portions which cooperate with ratchet means positioned on the other cap to provide a further, on-screwing drive means which is engagable in the rest position of the caps.

8. A closure according to claim 7 wherein the rib portions engaging the ratchet means are stepped in height.

9. A closure according to claim 7 or 8 wherein the said ratchet means consist of spring fingers extending from the lower surface of the outer cap.

10. A closure according to any of claims 1 to 9 wherein the inner cap comprises a central cylindrical spigot which cooperates with a tamper indicator on the outer cap.

11. A closure according to claim 10 wherein the tamper indicator is in the form of a central orifice on the outer cap initially closed by a cover portion connected to the body of the outer cap by frangible means or such like.

Drawing