Closure for a container consisting of a lower closure part and a screw top
BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     This invention relates to a closure for a container, comprising a lower closure part and a screw cap, wherein the lower closure part can be connected to a container opening by a base element. The closure has a pouring spout with external threads, on which the screw cap comprising a cap bottom and cap shell having interior threads can be screw-fastened and unfastened. When fastened, the screw cap is secured against being unfastened by engaged connections. The screw cap can be unfastened by releasing the engaged connections. 
     DESCRIPTION OF PRIOR ART 
     A closure of this type is known from Geoart Patent DE 42 09 784 C2. In this known closure, an engaged connection is formed between the screw top and the body. To achieve this, the front face of the screw cap is provided with circumferential engagement receivers which are engaged by engagement cams formed on the body of a lower closure part, It is necessary to compress the body to release the engaged connections, so that the engagement cams are radially displaced inwardly and moved out of the engagement receivers in the cap shell. This displacement of the body requires a considerable effort, particularly when a thick closure for a large container is involved. 
     SUMMARY OF THE INVENTION 
     It is one object of this invention to provide a closure for a container comprising engaged connections that can be easily released without losing their function as a child safety device. 
     This object is achieved in accordance with the closure of this invention comprising a screw cap having a cap shell which terminates in at least one engagement flap in an area of a free front face of the screw cap. An annular flange, which projects in the direction of the cap shell and partially covers the engagement flap is formed on the closure in a transition area toward the pouring spout. The annular flange is provided with engagement cams on its inside facing the engagement flap, which have a shallow rising flank in the direction of screw-fastening. The shallow rising flanks make a transition into steep engagement flanks and form engaged connections with the engagement flaps of the screw cap. The engaged connection can be released by a radial displacement of the engagement flaps. 
     The engagement flaps can be pushed inward by grasping and compressing the screw cap, which causes the engaged connection with the engagement cams on the inside of the annular flange to be released. Thus, the engagement flaps of the screw cap pass by the engagement flanks of the engagement cams, and the screw cap can be unscrewed from the pouring spout. The positions of the engagement flaps can be easily recognized so that it is not difficult for an adult to release the child safety device. The operation of the closure is not hampered by the additional annular flange on the lower closure part, in contrast to conventional closures with the engagement cams on the body. 
     In a preferred embodiment of this invention, two engagement flaps are disposed diametrically on the cap shell and an engagement cam is associated with each engagement flap on the lower closure part. Both engaged connections are simultaneously released by pressing together the lower area of the cap shell when the screw cap is grasped at the engagement flaps. The screw cap grasped and compressed in this way can then be simultaneously unscrewed from the pouring spout. 
     In accordance with another preferred embodiment of this invention, the pouring spout makes a transition via a shoulder into the body of the lower closure part. The annular flange at the shoulder is formed concentrically with respect to the pouring spout and together with the pouring spout forms an annular receptacle for the engagement flaps of the screw cap. 
     In another preferred embodiment, the engagement flaps have thin walls that extend over a portion of the circumference of the cap shell and can be easily displaced radially. Thus, a greater surface area for grasping the screw cap is achieved. 
     The invention will be described in detail by reference to preferred embodiments shown in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a partial cross-sectional view of a closure according to one embodiment of this invention, in the secured closed position, and 
     FIG. 2 shows a cross-sectional view of a closure according to one embodiment of this invention along the line II--II of FIG. 1. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The closure, according to one embodiment of this invention, comprises a lower closure part 10 comprising a base element 11, a body 12 and a pouring spout 15. The base element 11 can be engaged in a container opening. The body 12 is extended in FIG. 1. The pouring spout 15 has an exterior thread, and a screw cap 20 provided with an interior thread can be fastened or unfastened from the pouring spout 15. The screw cap 20 has the interior thread on the inside of a cap shell 21. In the delivered state, the pouring spout 15 is closed by a seal plate 16. The seal plate 16 can be torn from the pouring spout 15 by a gripping tongue 17. 
     At a free front face, the cap shell 21 of the screw cap 20 terminates in two engagement flaps 22 located diametrically opposite each other and extending over a part of the circumference of the screw cap 20, as shown in FIG. 2. A shoulder 13 is positioned at a transition from the pouring spout 15 to the body 12. An annular flange 14 extending toward a cap bottom of the screw cap 20 is formed on the shoulder 13, and together with the pouring spout 15 forms a receiving space 26 for the engagement flaps 22 when the screw cap 20 is screwed on the pouring spout 15. On an internal surface facing the engagement flaps 22, the annular flange 14 has engagement cams 23 which have shallow rising flanks 25 in the screw-fastening direction. The shallow rising flanks 25 make a transition into steep engagement flanks 24, the backs of which are engaged by the engagement flaps 22 of the screw cap 20. The annular flange 14 partially covers the engagement flaps 22, so that a portion of the engagement flaps 22 is still visible, and in this way marks the starting points for grasping the screw cap 20. 
     If the screw cap 20 is grasped in the area of the engagement flaps 22 and compressed, the engagement flaps 22 are brought out of engagement with the engagement cams 23 on the annular flange 14. The screw cap 20 can then be unscrewed from the pouring spout 15. 
     When screw-fastening the screw cap 20 on the pouring spout 15, the engagement flaps 22 slide over the shallow rising flanks 25 of the engagement cams 23 on the annular flange 14, but during unscrewing they push against the steep engagement flanks 24 of the engagement cams 23. 
     Normally a single engaged connection suffices as a child safety device. However, the two diametrically positioned engaged connections increase safety and make it easier for adults to release the child safety device. 
     A closure with a resiliently extendible body 12 in accordance with one preferred embodiment of this invention is illustrated in FIGS. 1 and 2. However, it is apparent that the child safety device can be used with any arbitrary closure. In another preferred embodiment, the annular flange 14 is positioned directly on the container. In yet another preferred embodiment, the annular flange 14 is positioned directly on the lower closure part 10.