Patent Publication Number: US-6035679-A

Title: Hinged lock key

Description:
BACKGROUND OF THE DESCRIPTION 
     The subject of the present invention is a hinged lock key. 
     Hinged lock keys, or keys with a bow that folds with respect to the shank, are known. These keys are used in particular when, in the use position, the bow of the key projects from the lock so as to constitute a hazard or such that someone moving or passing close to it may knock into it; a typical example would be keys for locks in desk drawers. If it is knocked, the bow folds back so as to avoid an accident. The bow may also be held in the folded position when the key is inserted in the lock but is not being used, so as to avoid people knocking into it in the first place. 
     The bow of these keys usually comprises a flat shaped element, made of fairly rigid plastic, which has a C-shaped cavity housing a small block, made of the same plastic, from which the metal shank extends; a pin which is inserted forcibly into the wings of the C-shaped cavity and into the block allows the bow to rotate with respect to the shank and also has the function of securing the shank in the block; projections are formed in the cavity and matching recesses are formed in the block so as to produce a snap-fastening connection that keeps the working position of the bow stable and allows the bow to rotate, in other words to bend, with respect to the shank, simply by overcoming a given force. 
     This known structure for a hinged key is expensive to produce because it consists of four pieces. Also, during the production process, it is firstly necessary to mould the flat shaped element and the block; then the shank has to be inserted into the block, and then the block/shank assembly into the cavity in the flat element; lastly, the pin needs to be inserted very accurately into appropriate aligned holes made in the flat element and in the block. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a hinged lock key which is cheaper to produce and is at least as effective as known hinged keys. 
     This object is achieved by means of a hinged lock key comprising a bow and a shank, in which the bow is hinged with respect to the shank and moves between the working position and folded positions, and in which a snap-fastening connection is provided which keeps the working position stable and enables the folded positions to be reached by overcoming a given force, characterized in that two opposite transverse arms, on which the bow is hinged, extend from the shank and in that the snap 15 fastening connection acts between the bow and the arms. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to gain a better understanding of the invention a description is given below of a non-limiting example thereof which is illustrated in the appended drawings, in which: 
     FIG. 1 shows a partially cut-away perspective view of a hinged lock key according to the invention; 
     FIG. 2 shows the degree to which the bow of the key in FIG. 1 can bend with respect to the shank; 
     FIGS. 3, 4 and 5 show consecutive side views of the folding movement of the bow of the key in FIG. 1 with respect to the shank; 
     FIGS. 6, 7, 8 and 9 show perspective views of the stages involved in the assembly of the key in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The lock key shown in FIG. 1, denoted overall by the reference 10, comprises a bow 11 via which it is gripped and a toothed metal shank 12 designed to be inserted into the lock. 
     Two opposite transverse arms 13, having a quadrilateral section and formed in one piece with the shank, extend from the shank 12, at the point where it is connected to the bow 11. 
     Hinged on to the arms 13 is a metal core 14 consisting of a spring formed by a folded piece of sheet steel with shaped ends 15 and 16 that enclose the arms 13 on three sides, following their shape. The metal core 14 is embedded in a soft, suitably shaped, elastic casing 17, for example made of silicone rubber. The casing 17, together with the core 14, forms the bow 11. 
     As shown in FIG. 2, the particular type of connection between the arms 13 of the shank 12 and the core 14 of the bow 11 allows the bow to bend through 90° in both directions with respect to the shank. More specifically, with reference to FIGS. 3, 4 and 5 which show the bow 11 folded at 90° in one direction, the core 14 rotates around the arms 13 and opens up slightly in order to get over the edges of the arms, elastically closing up again as soon as it has got past them; this opening up of the core is made possible by the elasticity of the casing 17. In this way, a snap-fastening connection is produced between the bow 11 and the arms 13 of the shank 12 which keeps the working position stable and enables the folded positions to be reached by overcoming a given force. 
     FIGS. 6, 7, 8 and 9 illustrate the sequence of stages in producing the key 10. As may be seen, the core 14 is firstly attached to the arms 13, the core is then pressed closed around the arms and, lastly, the casing 17 which encloses the core is moulded. 
     The key 10 is extremely inexpensive to produce because the operations described above can be carried out automatically using suitable machinery. 
     The casing made of soft elastic material is also particularly advantageous since, in conjunction with the ability of the bow to bend, it helps to minimize the effects of any knocks the bow may sustain. Furthermore, the softness of the bow prevents it from damaging parts of the structure to which the key and the corresponding lock may be attached; for example. if the key and the lock are applied to a door in a piece of furniture and the door is opened abruptly, this may cause the bow of the key to knock against part of the piece of furniture; however, because the casing is soft, the piece will not be damaged. 
     When the bow folds back as a result of its being knocked, the elasticity of the core allows the bow of the key to snap automatically into one of the two positions at 90° and for it to be held securely in this position. In other words, the key 10 has two stable, and therefore well-defined, folded positions. In contrast, in the known hinged keys with a pin and block discussed in the introduction, once the bow is moved out of the working position, it is free to rotate, even if in a limited way, about its pin, which therefore means that the folded positions are not stable. 
     Needless to say, variations and/or additions may be made to the embodiment described and illustrated. 
     The shape of the core and the cross-section of the arms may vary as long as they provide the snap-fastening connection referred to within the scope of this embodiment. For example, the cross-section of the arms and the corresponding shape of the ends of the core may have a polygonal shape other than a quadrilateral shape. The core may be made from any suitable material, not just metal. The casing, too, may be made from any soft material. 
     It would also be possible to envisage making the bow from a rigid, rather than soft, material, with suitable notches or equivalent provisions to make it yield elastically. It would also be possible to omit the core and make the bow from a rigid material, again with provisions to make it yield elastically, and additionally with suitable shaped portions, matching the shaped ends of the core, that are joined to the arms of the shank. In cases such as these, there is also the advantage of low production costs, however, the advantages that come with having a bow made of soft material are lost. 
     The arms could have a circular cross-section and the shaped ends of the core or the shaped portions of the bow could snap-fasten by means of projections and matching recesses formed in the arms and in the shaped ends or portions respectively. 
     The specific embodiment illustrated in the example referred to above has, however, proved to be particularly advantageous. 
     The hinged key described above may be used in any situation which requires a hinged bow.