Tamper-Proof Closure With Safety Means

1. Field of the Invention

This invention relates in general to tamper-proof plastic closures for containers having a screw-threaded neck, and has specific reference to closures of this type comprising in addition a safety means intended more particularly for containers such as bottles or the like which should not be opened by children, for instance bottles containing drugs or other dangerous products.

2. Description of the Prior Art

In the U.S. Pat. No. 3,863,796 to Roy there is disclosed a safety closure device comprising an internal plug screwed to the neck of the container and housed in a covering cap formed on the inner peripheral surface of its upper wall with a series of teeth adapted to engage corresponding teeth formed on the outer peripheral surface of the upper wall of said plug when a pressure is exerted in the axial direction throughout the cap surface against the force of a central spring. However, this device is not tamperproof, since even a child can produce this meshing engagement by merely depressing the cap as a whole.

According to a first feature characterizing the closure device according to this invention, this device comprising an internally screw-threaded or tapped plug engaging on the one hand the externally screw-threaded neck of a container by which it is retained through the engagement of a bead formed integrally with the neck into a groove formed at the bottom of the external skirt of the plug, said tapped plug being furthermore surrounded in smooth frictional contact by a covering cap having a bulged and flexible top wall provided on its inner surface with central means adapted to engage means projecting from the central area of the plug when a sufficient pressure is exerted on said top flexible wall, to permit the release of said plug from said retaining ring and therefore the unscrewing of said plug.

According to another feature characterizing this invention, the outer surface of the top wall of said covering cap comprises around its bulged central area at least one circular rib acting as an abutment member for stopping the movement of said central area away from the registering central portion of the plug.

According to a further feature characterizing this invention, the means for rotatably driving the plug from said cap and thus opening the container or bottle comprise ribs formed on the outer surface of the central area of the plug and projections formed on the inner surface of the top wall of said covering cap, or vice versa. Said projections are adapted to engage and drive the ribs formed on the outer surface of the bottom of said plug when a sufficient pressure is exerted on the upper central flexible portion of the cap within the perimeter of said circular abutment-forming rib. To this end, the resistance of said cap to the necessary distortion may be calculated with a view to prevent a child from causing said cap and plug to come into mutual meshing engagement.

Thus, if one simply tries to unscrew, the assembly as would naturally occur to anybody, the cap will simply rotate loosely around the plug.

A typical form of embodiment of the closure device according to this invention will now be described by way of example with reference to the attached drawing, in which:

FIG. 1 is a diametral section showing the neck of a container to which a safety closure has been fitted.

FIG. 2 is a plan view from above of the device illustrated in FIG. 1.

FIG. 3 is a similar to FIG. 1 but shows the closure plug ready to be unscrewed, and

FIG. 4 is a fragmentary sectional view showing a modified form of embodiment wherein the neck of the container has been adapted for using a tear-off guaranty strip.

The closure device illustrated comprises an internally screw-threaded or tapped plug 1 and a complementary of covering cap 2.

The tapped plug 1 of any suitable type comprises in this example an internal skirt 5 and an external skirt 6 and is fitted to the screw-threaded neck 3 of a container, for example a bottle. Just beneath its tapped portion 3a the neck 3 comprises a circular bead 3b adapted to be force fitted into a circular groove 6b formed in the plug 1, when the latter has been screwed home and sunk with force. The plug 1 is thus retained on the neck 3 due to the penetration of the bead 3b thereof into the plug groove 6b (FIG. 1).

The bottom 4 of plug 1 comprises in the central carea of its top wall a plurality of ribs 4a forming for example a cross-shaped pattern (see FIG. 2).

The covering cap 2 is fitted in smooth frictional contact over the plug 1 and comprises a circular top wall 8 and a lateral cylindrical skirt 9 of which the lower reinforced edge 10 constitutes a heel adapted to retain the plug 1 within said cap 2. The top wall 8 of suitable resilient material has a bulged central portion and comprises along its outer periphery and registering with the top edge of neck 3 a circular rib 11. This rib 11 bears with its inner edge 11a against the bottom 4 of plug 1 and acts as an abutment member for keeping the top wall 8 of cap 2 and the central portion of plug 1 somewhat spaced from each other. This abutment member 11 prevents any distortion of the top wall 8 of cap 2 when a pressure is exerted through the surface of the cap top wall 8. The central bulged portion of this wall 8 carries internal projections 8a adapted to fit into corresponding cavities formed in the outer surface of the bottom wall 4 of plug 1 by the cross-shaped ribs 4a when a pressure sufficient for producing the mutual meshing engagement of said projections 4a and 8a and therefore the driving contact between the plug 1 and cap 2 is exerted against the central area of the top wall 8 inside said abutment member 11 (FIG. 3).

The closure device according to this invention operates as follows:

The plug 1 covered by the cap 2 is driven with force into the neck 3 of the container until the bead 3b of neck 3 engages the groove 6b of the plug. In this position the projections 8a of cap 2 do not contact the ribs 4a of plug 1. If one attempts to unscrew the plug in the usual was, the covering cap 2 will rotate freely in one or the other direction on the plug 1, without unscrewing the latter, since the bead 3b of neck 3 engaging the groove 6b plug 1 plug1 will hold the latter thereon, and if the top wall of cap 2 is depressed home the abutment member 11 will prevent the distortion of the central bulged portion 8.

To unscrew the plug, an axial pressure must be exerted on the central bulged area of the top wall 8 of cap 2. This can be done for example by holding the cap-covered plug with the thumb and the second finger while exerting a pressure with the forefinger. In this case, the projections 8a will engage the cross-forming ribs 4a of plug 1 and drive the latter. The effort transmitted through the screw threads 3a permits of releasing the plug, the latter being freed from the bead 3b of neck 3 due to the resiliency of the plug material.

To refit the plug onto the neck it is only necessary to re-screw it while keeping the top wall 8 of cap 2 in meshing engagement with the bottom 4 of said plug, i.e. by exerting on the cap 2 the same pressure as when attempting to remove the closure.

This pressure is subordinate to the thickness of wall 8. This thickness will be selected to such a value that the effort to be exerted thereon be somewhat in excess of the effort that a child can exert with his or her fingers, while remaining easy for an adult, since the safety means of the closure device of this invention is intended more particularly for bottles or like containers that should not be opened by children.

This structure may be used on a bottle having a neck contour designed for a tear-off strip 12 provided at the bottom edge of the skirt of plug 1 and retained by an integral bead 14 engaging a circular groove 13 formed in the neck beneath the bead 3b (FIG. 4), for example according to the structure disclosed in the French Pat. No. 7,405,926 filed on Feb. 21, 1974 in the name of Captocap Limited.

Various modifications and variations may be contemplated within the field of technical equivalence in the practical embodiment of this invention, without inasmuch departing from the basic principles thereof, as will occur to those conversant with the art. Thus, notably, the means for drivingly coupling the cap 2 and plug 1 by exerting a pressure on the top wall 8 of said cap may be inverted, i.e. by providing projections 8a on the plug 1 and the ribs 4a on the inner surface of the top wall of cap 2; besides, other means for causing the cap and plug to be drivingly interconnected at will may be contemplated within the scope of this invention.

Finally, to improve the safety characteristic of this invention, a thin flexible strip 15 may be provided on top of said plug 1 for frictionally engaging the projections of said cap when the latter rotates loosely, thus producing a characteristic rattle noise for warning that somebody is handling the container.