Abstract:
The spring loaded tumbler is provided with a casing and a core. Latter has a limited travel towards the key passage, and is located in a stepped drilling in the cylindrical core. A sliding sleeve element is located on the core, which has a corresponding shape to that of the stepped drilling. The tumbler according to the present invention can be inserted in normal cylinder locks and effectively prevents unauthorized opening without the use of a key or damage to the lock.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a tumbler in a cylinder lock having a core pin and a spring-loaded housing pin, which are supported in a radial bore of the cylinder housing and in a bore of the cylinder core, respectively, and which are brought into alignment by an insertable key introduced into the key channel. 
     2. The Prior Art 
     Cylinder locks having two-part tumblers are well known and have a high degree of security. However, unlocking methods have now been developed with which these cylinder locks can be opened without keys and without externally apparent damage to the locks. 
     SUMMARY OF THE INVENTION 
     It is now the object of the invention to devise a cylinder lock of the above type which cannot be opened with these methods. 
     This object is attained in accordance with the invention by providing that the core pin has a sheathlike slide element, which is disposed behind the head of the core pin and is displaceable in the longitudinal direction with respect to the bore and to the core pin. The effective portion of the tumber always remains movable if the aforementioned unlocking methods are used, so that its measurements cannot be learned. Unlocking methods involving the use of force also fail, because once again the effective portion of the core pin cannot be fixed in place. 
     The tumbler according to the invention is simple to mass produce. No modifications to the other parts of the cylinder lock or to the key are necessary. The cylinder lock can be adequately secured against the above unlocking methods by using at least one tumbler according to the invention, along with the usual tumblers, in the cylinder lock. 
     By manufacturing the tip of the core pin as a separate part and securing the tip with an interference fit on the pin body, it becomes possible to make the tip from a material that is especially secure against being drilled open. If the tip is made from a hard metal material, wearing down of the tip from use is moreover largely avoided. 
     The embodiment of the tumbler in which the core pin has a bore, in which a locking pin that is displaceable in the longitudinal direction with an outward limitation by a stop is supported, and disposed in the bore is a compression spring, which presses in a biased manner upon the locking pin, which in turn presses against the housing pin additionally prevents unlocking methods in which the core and housing pins are separated so that the rotor can be rotated briefly. 
     Further advantageous embodiments are disclosed in the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention will be described below in further detail, referring to the drawings, in which: 
     FIG. 1 shows a longitudinal section through a core pin; 
     FIG. 2 shows a cross section through a portion of a cylinder lock with a tumbler inserted, the tumbler being shown partly in projection and partly in section; 
     FIGS. 3a and 3b shows a cross section through a cylinder lock with a tumbler in accordance with a variant of the present invention; and 
     FIG. 4 shows a longitudinal section through a core pin in accordance with a further version of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a known manner, the lock cylinder shown in FIG. 2 has a stationary cylinder housing 12, which is located in a cylindrical sheath 11 and in which a cylinder core 13 is rotatably disposed. The cylinder housing 12 and the cylinder core 13 have radial bores 17a and 17b, in which spring-loaded tumblers are displaceably supported. One spring 16 is located in each housing bore 17a, supported against the sheath 11 and pressing in a biased manner against a housing pin 15, which in turn presses a core pin 10 radially inward against a key that is to be introduced into the key channel 14. 
     As FIG. 1 shows, the core pin 10 has a tip 3, which includes a connecting portion 3a and a head 3b having a control face. The head 3b may also have a plurality of control faces, however, to increase the number of locking possibilities in a known manner. The tip 3 preferably comprises a hard metal material, or some other mechanically resistant material that is secure against being drilled open and is wear-resistant, and is secured with an interference fit in a bore in the pin body or shaft 5. 
     A sheathlike slide element 1 is displaceably supported on the body 5. Both the slide element 1 and the body 5 are offset in diameter in stepped fashion on the outer end, so that the slide element 1 is outwardly displaceable in a manner limited by a stop and has a wider sheath portion 1a and a narrower sheath portion 1b. Inwardly, the sheath portion 1b of the slide element 1 is limited by a stop in the form of the radially outwardly protruding head 3b. 
     In FIGS. 3a and 3b, a core pin 30 is shown which besides the slide element 1 additionally has a locking pin 24. The locking pin is supported in a stepped bore 27 in the pin body 26 such that it is outwardly limited by a stop. A compression spring 25 is located in the stepped bore 27, supported against the tip 3 and pressing in a biased manner against the locking pin 24, which on its outer end rests on the housing pin 15. The tension of the spring 25 is selected such that the locking pin 24 does not move the housing pin 15 out of its position that locks the cylinder. In the position shown in FIG. 3a, however, the spring 25 does have a tension great enough that the locking pin 24 follows the housing pin 15 substantially without any delay when the two pins are separated from one another. 
     The mode of operation of the locking pin 24 is shown schematically in FIG. 3b. The housing pin 15 is briefly moved here, by a known unlocking method, into an unlocked position, while the core pin 30 remains in its original position. Nevertheless, the cylinder core cannot be rotated, because the locking pin 24 projects beyond the shear plane 32 and locks the cylinder. 
     The core pins 10 and 30 can be inserted into the usual stepped bores 17b in the cylinder core 13. Because of the stepped embodiment of the bore 17b and a corrresponding stepped embodiment of the slide element 1, the displaceability of the slide element 1 and of the entire core pin 10 or 30 toward the key channel 14 is limited. 
     The core pin can also be embodied as shown in FIG. 4. In this core pin 43, the body is manufactured in one piece and has a cylindrical shank 41 and a head 40 having an approximately hemispherical control face. A cylindrical slide element 42, which is somewhat shorter than the shank 41, is displaceably supported on the shank 41. Upon a displacement in the axial direction, the sheathlike slide element 42 meets a stop at the head 40 in the inward direction and a stop on the housing pin 15, not shown here and embodied as described above, in the outward direction. The core pin 43 is particularly cost-effective in its manufacture and is particularly well suited for a cylinder lock having a serrated type of key. 
     The above-described core pins 10, 30 and 43 have an annular gap 18 or 48, respectively, between the slide element 1 or 42 and the head 3 or 40, respectively. These gaps are approximately 0.4 mm wide, viewed in the longitudinal direction of the core pin and are formed because the slide element is shorter by 0.4 mm than the body of the corer pin. The slide element may be between 0.3 mm and 0.7 mm shorter than the body. A compression spring 19 (shown only in FIG. 3a), which presses the slide element 1 against the shoulder of the pin body 5, or the slide element 42 against the housing pin 15, can be disposed in the gaps 18 and 48, respectively. The tension of this compression spring is comparatively low but assures that the gap 18 is maintained when the core pin 10, 30 or 43 is displaced outward. In the version of FIG. 4, this compression spring has the further advantage that the slide element 42 in this case also assumes the mode of operation of the locking pin 24. The slide element 42 and the compression spring thus effectively prevent the lock from being unlocked by separating the core and housing pins, and also at the same time assure that the effective portion of the core pin always remains movable during attempts to force the lock or gauge its measurements. 
     When the lock is opended by an authorized person using the proper key, the tumbler according to the invention functions in the same manner as a conventional tumbler.