Child Resistant Closure

Abstract

A two-piece closure in which the inner closure member is formed of metal and composed of a circular top panel with integrally formed depending cylindrical skirt. The skirt is provided with the usual threads for attachment to the finish of a container. The lower end or edge of the skirt terminates in a rolled head or wire. The skirt portion just below the top panel is formed with knurling. A plastic overcap, having integrally formed, downwardly projecting spring members, is formed with a depending skirt which is adapted to enclose the metal inner closure. A bead is formed at the bottom of the skirt of the outer closure or covercap to retain the two caps loosely as a unit. Inwardly projecting ribs at spaced intervals about the inner surface of the covercap cooperate in one axial position to interlock with the knurling so as to provide means for removing the inner cap and in the unstressed or normal position, the tabs will maintain the two caps in a spaced relationship such that the outer cap will rotate freely relative to the inner cap.

Description

BACKGROUND OF THE INVENTION

It is desirable, for a closure to be of the child resistant type, that it provide a configuration and require manipulation which a child would not normally be considered capable of performing.

Many studies have been conducted with respect to determining the types of closures which would be most resistant to opening by small children and a consensus appears to be that a closure which requires a dual manipulation has proven to be the most difficult for a child to successfully remove without special instructions. The two manipulations involved in the present invention are the requirement that the outer closure or shell be pushed downwardly prior to rotation in order to effect opening of the container for access to the contents.

DESCRIPTION OF PRIOR ART

Two-piece closures of the general type disclosed herebelow are known in the art; however, they have not been widely accepted because of the requirement that special cap-applying equipment be used to apply the sealing cap to the finish of a container, or because the two-piece combination had to be expensively formed of a plurality of parts in order to provide the safety function.

SUMMARY OF THE INVENTION

This invention is directed to a child resistant closure which is comprised of a knurled metal closure having a threaded skirt and outwardly rolled lower rim portion for engagement with the container finish to provide a closure that is capable of forming a liquid tight seal with the finish of the container. A plastic overcap is formed with a horizontal top panel to which a plurality of elongated, downwardly extending tabs are attached, with the tabs having their free ends terminating in a plane below the panel. The tabs are joined to the panel along cordal lines and extend downwardly and circumferentially of the overcap, with the free ends of the tabs having their lower edges defining horizontal radial lines with respect to the overcap axis. A plurality of groups of ribs formed in the skirt portion of the overcap and extending inwardly thereof are adapted to engage the knurled portion of the metal closure when the overcap is pushed downwardly relative to the metal closure, with means provided within the overcap to prevent overstressing of the tabs and retaining the overcap in position over the metal closure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view illustrating the metal closure and plastic overcap of the invention in position prior to assembly;

FIG. 2 is a bottom view taken along lines 2--2 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3--3 of FIG. 1;

FIG. 4 is a side elevational view of the cap of FIG. 1 in assembled position with the overcap shown in cross-section; and

FIG. 5 is a view, similar to FIG. 4, illustrating the relative position of the overcap when pushed downwardly on the metal cap preparatory to removal from a container.

The closure of the invention with reference to the drawings is comprised essentially of two pieces. The first piece takes the form of a regular knurled metal, threaded closure or shell 10 formed of a top panel 11 and depending skirt portion 12. The skirt portion, just beneath or adjacent the panel 11, is provided with external knurling 13. The lower edge of the skirt portion 12 of the shell 10 is formed with the usual wire or rolled portion 14. The closure 10 will have the usual disc gasket contained therein.

An overcap or shell 15, formed of a thermoplastic material such as polyethylene, polypropylene or other plastic material having some flexibility, is formed with a top circular panel portion 16 and depending cylindrical skirt portion 17. The center portion of the panel 16 is provided with a depression 18 which provides for gating of the plastic material in injection molding of the overcap.

The inner surface of the panel portion 16 of the overcap, as best shown in FIGS. 1 and 2, has formed integral therewith a plurality of tabs 19 having a rectangular cross-section. The tabs 19 extend downwardly from the interior surface of the panel portion 16 and are attached to the panel along lines 20 which, in effect, are chords of the circular configuration of the panel portion 16. Furthermore, the tabs 19 extend downwardly and generally circumferentially with respect to the axis of the overcap, with the lower ends 21 of the tabs being squared off and located on radial lines with respect to the axis of the shell or overcap 15.

The ends 21, when the two caps are in assembled position as shown in FIG. 4, will be slightly spaced from the upper surface of the top panel portion 11 of the inner closure 10. Slight upward movement of the closure 10 will cause the ends 21 of the tabs 19 to engage the surface preventing any further relative movement without the requirement of a sufficient force to flex all six of the tabs 19.

The overcap or shell 15, as best shown in FIGS. 1, 4 and 5, is formed with an inwardly extending annular shoulder or ledge 22 whose function is to prevent movement of the inner shell within the outer shell beyond the position shown in FIG. 5.

As shown in FIG. 2, a plurality of ribs 23 are formed in four sets of ribs grouped in groups of seven with the sets located generally at 90.degree. intervals about the inner circumferential wall of the skirt portion 17. The upper ends of the ribs 23 terminate at the shoulder or ledge 22.

In addition to the ledge 22, to prevent relative movement of the caps to the extent that the tabs 19 perhaps would be overstressed or broken, the outer cap 17 is provided with a lower ledge or shoulder 24 which will be engaged by the wire portion 14 of the inner cap 10 when the two caps are in the position shown in FIG. 5. The specific reason for the ledges 22 and 24 is dictated from applicant's experience that with prolonged top loading of the outer cap 15 relative to the inner cap 10, the tabs become bent beyond their elastic limit. If the caps are permitted to move such that the tabs become too greatly stressed, then they tend to break or fracture at or adjacent their lines of juncture with the panel portion 16. Obviously, if the tabs become fractured or permanently stressed to the extent they are not able to recover, then, when the top load is removed the two caps are not separated and the function of the cap as a two-piece child resistant closure would be lost.

The overcap also is formed with an inwardly extending annular bead 25 formed adjacent the lower edge of the skirt serving to retain the two shells as an assembled unit, once they have been assembled into the position shown in FIG. 4. After assembly of the two pieces, it is possible for the outer plastic shell to be removed from the metal closure; however, the manual strength and dexterity of children's hands and fingers would not be sufficient to cause removal.

The function of the closure should be apparent from the foregoing description, in that while the closure combination is in the normal position shown in FIG. 4, rotation of the outer cap or the overcap 15, will be free and unrestricted relative to the knurled cap 10. Only by downward force being applied to the overcap 15 will the ribs 23 engage the knurling 13 so as to provide a rotary connection between the two caps. The ribs are formed in sets principally because of the difficulty of being assured that the knurling on the metal caps is always of the same number and at uniform spacing. By providing ribs in sets which are symmetrically located, there is a positive assurance that a number of the ribs, upon displacement of the two caps to the position shown in FIG. 5, will engage in the knurling. The tabs 19 are of sufficient flexibility that upon release of the force on the top of the overcap, the overcap will move upwardly relative to the closure 10, thus again rendering the closure combination disengaged to the extent that the outer cap will rotate freely on the inner metal cap.

Claims

I claim:

1. A child resistant closure comprising, in combination, a knurled metal closure having a threaded skirt and outwardly rolled lower rim portion and a plastic overcap, said overcap comprising a generally horizontal panel and integral depending skirt extending below the lower rim portion of the metal closure, a plurality of elongated, downwardly extending flexible tabs of substantially rectangular cross-section integrally formed in the undersurface of said panel and having their free ends terminating in a first plane below the panel, said tabs being joined to the panel along chordal lines and extending downwardly and circumferentially of said overcap, the free ends of said tabs having their lower edges describing horizontal radial lines with respect to the overcap axis, a plurality of groups of ribs formed in the skirt portion of said overcap and extending inwardly thereof, the lower ends of said ribs lying in a second plane slightly above said first plane, an annular, inwardly extending shoulder having its lower, horizontal surface coinciding with the upper ends of said ribs, said shoulder being of a height greater than said ribs, whereby axial displacement of said overcap in a downward direction will slightly bend said tabs and move said ribs into engagement with the knurling of said metal cap to permit removal of said metal cap by rotation of said overcap and said tabs will be prevented from excessive bending by engagement of the upper end of said metal cap and said shoulder.

2. A child resistant closure comprising, an inner metal threaded part adapted to be screwed on a threaded container neck, an outer plastic part encompassing said inner part, said inner and outer parts being capable of relative rotary and axial sliding movement, internal ribs formed in said outer part, knurling formed on the outer surface of said inner part, said knurling and ribs being engageable in one position of axial displacement of said two parts and disengaged in a second axial position of said parts, a plurality of flexible tabs of substantially rectangular cross-section formed integrally with said outer part and extending downwardly and circumferentially of said outer part for maintaining said parts in said second position, said flexible tabs being joined to said outer part along circumferentially spaced chord lines and having squared-off free ends which engage with the outer surface of the inner part, outwardly extending means formed on the lower edge of said inner part, and inwardly extending means formed on the lower edge of said outer part for loosely retaining said parts in assembled relationship, inwardly extending first annular shoulder means formed in said outer part immediately above said ribs and extending inwardly a distance greater than said ribs, and second annular ledge means formed in said outer part intermediate said ribs and said lower edge for preventing axial, relative movement of said two parts beyond said second position.