Keys

Abstract

The invention is for a key comprising a bit having at least one tumbler engaging surface area including a plurality of step portions each step portion being adapted to engage an appropriate tumbler in said lock with which the key is to be employed each step being shaped or cut in its extremity to enable a surface area of the step to engage a key engaging portion of said tumbler wherein the thickness of the step portions is varied along the length of a bit constituted by said portions.

Description

The present invention relates to keys and has particular reference to keys suitable for use with a lock as described in Application Ser. No. 273,863, filed July 21, 1972. This co-pending Patent Application describes a key operable plug mechanism comprising a side bar movable with respect to said plug between a lock position in which the side bar projects from said plug and the free position in which the side bar is disposed substantially within the periphery of said plug, a plurality of tumblers disposed within said plug each capable of rotational movement with respect to said plug and to each other, each tumbler having an engaging surface adapted to engage at least a side part of a key bit and a peripheral notch predetermined angular relationship with the key engaging surface, and a cylinder adapted to encompass said tumblers whereby in the locking position of the side bar, the said peripheral notches of the tumblers are dispersed so that the periphery of at least one tumbler prevents movement of said side bar to the unlocked position, the arrangement being such that on insertion and rotation of an appropriate key, the engaging surface of the tumblers will engage said key for rotation therewith to align said notches adjacent said side bar so that continued rotation of said key permits rotational movements to be transmitted to said side bar by the cylinder to permit said side bar to move to said free position.

The said co-pending patent application also includes a key operable assembly for a lock which assembly comprises a body member having a generally cylindrical bore, a rotatable cylinder disposed within said bore including a side bar movable between a locking position in which the side bar engages said body member to prevent substantial relative rotation between said plug and said body member and a free position in which the side bar is disengaged from said body member to permit said relative rotation, a plurality of tumblers disposed in substantially spaced parallel relationship with said plug and capable of rotation about an axis coaxial with said bore, each tumbler having a key engaging surface and a peripheral notch adapted to accommodate at least part of said side bar and a cylinder encompassing said tumblers and adapted to impart motion to said side bar, whereby when the side bar is in the locking position, the peripheral notches of said tumblers are dispersed so that a periphery of at least one of said tumblers prevents movement of said side bar out of engagement with said member and the arrangement being such that on insertion of rotation of an appropriate key, the tumblers are engaged by said key on rotation thereof to produce relative rotation between said tumblers or sets of tumblers to align said notches to allow movement of said side bar from said locking position to said free position and so that continued rotation of said key causes said cylinder to impart rotary motion to said side bar to obtain relative rotation between said plug and body member.

The present invention, therefore, relates to a key of the type adapted for use in conjunction with a locking mechanism described above comprising a bit having a substantially planar tumbler engaging side face having a plurality of step portions, each step portion being adapted to engage an appropriate tumbler in the said mechanism with which the key is associated, and each step being shaped or cut in its extremity from said pin so that a side face of said step will engage a selective key engaging surface in the associated tumbler whereby on insertion and rotation of the key within the mechanism, relative angular rotation occurs between the tumblers by virtue of the key engaging different engaging surfaces on the tumblers to align the side bar notches thereby permitting operation of the mechanism wherein the thickness of the step portions of the bit is varied along the length thereof.

Thus the configuration of the engaging face of the bit is other than planar and the corresponding key engaging surface of each tumbler in the lock is suitably configured to correspond therewith. In a preferred embodiment of the present invention, the thickness of the step portions is reduced at intervals along the body to provide varying thicknesses between various steps in the bit as well as providing various depths. In this way the angular disposition between the notch and the key engaging surface of each tumbler then may be varied from tumbler to tumbler the arrangement being such on rotation of the key in the lock the key engaging surfaces are aligned with the configured key engaging surface of the key itself thereby aligning the said notches.

This feature has the advantage that the keys in accordance with the present invention are difficult to reproduce on a standard key duplicating machine since the standard key duplicating machine is only concerned with the reproduction of varying depths of each step along the bit.

It will be appreciated, therefore, that the present invention can be applied to keys of the pin type and flat types with a plain bit or a fluted bit the configuration of the key engaging surface being varied on one or both sides.

Following is a description by way of example only with reference to the accompanying informal drawings and embodiments in accordance with the present invention.

FIG. 1 is a side view of a key in accordance with the invention engaging a cylinder mechanism.

FIGS. 2 to 11 are sections through the key of FIG. 1.

FIG. 12a is a side view of a key showing the step portion of the bit sub-divided into step depth to show the manner in which the thickness is varied.

FIGS. 12b and 12c show the said key in engaging position with tumbler.

FIG. 13 is a section through a cranked key bit showing the appropriate variation in the shape of the pick up steps of each tumbler.

FIGS. 14 to 18 indicate alternative configurations of keys in accordance with the present invention.

FIG. 19 is a section through a flat key in accordance with the present invention.

FIG. 1 it will be seen that the bit 10 extends substantially radially of the pin 11. The thickness of the bit as indicated by 't' (see FIG. 2) is substantially uniform for the whole depth of the bit 10. The bit 10 is subdivided by a dotted line 12 to indicate the different step depths to which the extremity surface 13 of bit 10 may be cut to pick up the various key engaging surfaces of the tumblers of the locks specifically described in co-pending application No. 273,863, filed July 21, 1972. In this embodiment, therefore, the key engaging surface is the surface indicated generally at 14. FIGS. 3 to 11 show each of the specific steps along the key of FIG. 1 showing how the thicknesses vary from step to step along the bit section.

FIG. 12a is a side view of a key in accordance with the present invention showing one of the steps of reduced depth also having a thickness of a portion of the said step reduced.

FIG. 12b shows a section for key pin and bit along the line A -- A of FIG. 12a. The step portion has an extremity surface 20 determining the radial extent of the portion from bit 11. The tumbler engaging surface 21 is reduced at 22 to provide a step 23. Thus it will be appreciated that the reduced thickness will permit some rotation of the key alone, until the reduced surface abuts the tumbler engaging surface 74.

FIG. 13 shows a key pin 11 having a depending bit indicated generally at 30 having an upper portion 31 and a lower portion 32 joined by an intermediate cranked portion 33. In this case the key engaging surface 34 is configured or profiled in which case the corresponding surfaces on the tumbler key engaging surfaces can be suitably profiled.

FIGS. 14, 15, 16, 17 and 18 illustrate alternative configurations of key engaging surfaces. It will be appreciated that where left and right hand operated locks are employed, one key can be employed for two locks so that, provided the depths of the steps of the same in connection with each lock, the angular separation of the selected pick up step on each tumbler together with its associated notch is varied to take account of the varying thickness of the section of the key bit adapted to engage therewith by configuring opposed surfaces or at least one surface of the key. This one key can operate two locks by using different faces thereof whereby a similar key having a planar tumbler engaging face on the bit and having the same depth of bit pattern will operate only one of said locks. Where the key is configured on both surfaces then it is clear that the planar faced key will not open either of said locks.

FIG. 19 illustrates a key of the flat section whereby the tumbler engaging surfaces are denoted by fluted portion 30, 31 and 32 along one face of the key.

Claims

I claim:

1. A key for actuating a lock having a plurality of tumblers each of which includes a stepped notched area for accommodation of said key, comprising a shank supporting a bit having a predetermined length and thickness sufficient to actuate each of the plurality of tumblers, said bit having a bottom portion lying in a plane parallel with said shank and an intermediate portion further including front and rear surface areas at least one of which is modified longitudinally of its length, said bit further being varied in thickness longitudinally of its length in increments complemental to each of said tumblers.

2. A key as claimed in claim 1, in which said modified areas present a cranked intermediate portion, said portion causing at least one of said front and rear surface areas to be offset with respect to the plane of said shank and said bottom portion.

3. A key as claimed in claim 1, in which at least one of the surface areas of said bit is severed longitudinally of its length so as to vary the thickness of said bit in increments complemental to each of said tumblers.

4. A key as claimed in claim 1, in which the surface areas of said bit are arranged to actuate tumblers which operate in both clockwise and counterclockwise directions.