Cylinder lock

Abstract

A cylinder lock with a key plug rotatably mounted in the cylinder shell is described. The key plug has a plurality of tumblers that are set by the v bits of a key inserted in the key plug. The key is cut at three different levels and cut at three different angles. Each tumbler in the key plug may be positioned by the properly bitted key reciprocally to clear the shear line and also positioned rotationally to allow the fence to be cammed out of engagement with the cylinder shell. The key plug may then be rotated.

A side bar cylinder lock is also described with the same key cut at three different levels and cut at three different angles. The tumblers are positioned reciprocally and rotationally by the properly bitted key to allow the fence to be cammed out of engagement with the cylinder shell. The key plug may then be rotated.

Description

This invention is directed to a cylinder lock, and specifically directed to a new cylinder lock having a new and novel locking arrangement.

Conventional cylinder locks have a plurality of tumblers reciprocally mounted in the key plug. The key plug is rotationally mounted to rotate in the cylinder shell of the cylinder lock. The key plug is engaged in some manner with a locking mechanism with the cylinder shell so that the key plug may not be rotated in the cylinder shell. The reciprocally mounted tumblers operate the locking mechanism. In a pin tumbler cylinder lock, the locking mechanism consists of drivers associated with each tumbler. The drivers are in a driver bible rigidly formed with the cylinder shell. Driver springs normally urge the drivers and tumblers across the shear line between the key plug and cylinder shell, keeping the key plug from rotating in the cylinder shell. The drivers and tumblers may be separated across the shear line by a properly bitted key cut at a plurality of levels, so that the lock is unlocked, and the key plug may be rotated.

A side bar cylinder lock uses a locking mechanism consisting of a fence slidably engaged in a lateral slot in the key plug which is normally urged into engagement with the cylinder shell to keep the key plug from rotating within the cylinder shell. Each tumbler has a circular groove which may be termed a true gate, at a predetermined level so that by the insertion of a properly bitted key cut at a plurality of levels, the tumblers may be reciprocally moved to present all of the circular true gates to the fence. The fence may then be cammed out of engagement with the cylinder shell and the tip of the fence move in the true gates so that the key plug is unlocked.

The number of key changes possible in these cylinder locks is determined by the number of tumblers in the key plug, and the number of bitting levels in the operating key. The number of key changes refers to the number of different keys possible. For instance, in a cylinder lock with five levels, and five tumblers, it would theoretically be possible to have 3125 key changes. A number of these possible key changes must immediately be struck because backing of the key out of the lock would simultaneously raise all of the tumblers to the next higher level and unlock the lock in some combinations. Because of manufacturing tolerances and undesirable key cuts, the actual number of key changes possible is as low as one to two percent of the theoretically possible key changes. Thus there may actually only be thirty to sixty actual key changes in a five bitted level, five tumbler locks.

Due to conditions which arise in the construction of the lock parts under customary manufacturing tolerances, it is possible to effect minute rotary displacement of the key plug from its normal locked positions and thereby produce a slight offset shoulder formation or ledge by the key plug at the shear line between the key plug and the wall of the key plug accommodating bore, which will catch and support the edge of the lower end of the driver when tumblers are elevated. This property of the locks is taken advantage of in lock "picking" procedures by applying a special torque wrench to the key plug to force or stress the key plug in an angular direction about its axis of rotation and then manipulating the tumblers by a picking tool inserted into the key slot to individually lift the tumblers until the drivers catch on the shoulder or ledge formed when the key plug is thus stressed. When all of the drivers have been thus caught in the elevated position, the key plug can be turned to unlock the lock.

The locks may also be opened by "key jiggling" a lock, using a small group of select keys. These keys are then used by inserting a selected key in the key hole, pushing it in and out, torqueing it, with all of these motions carried out simultaneously, until one of the select group of keys opens the lock.

It is therefore an object of this invention to provide a new and improved cylinder lock having a significantly greater number of actual key changes.

Another object of this invention is to provide a new and improved cylinder lock which is difficult, if not impossible, to pick.

In summary, a new and improved lock with an accompanying key has been described. The cylinder lock operated by a single cut key has a cylinder shell, a key plug normally engaged in the cylinder shell, a first locking means operated by the single cut of the key, and a second locking means operated by the single cut of the key, so that the first and second locking means operated by the single cut on the key disengage the key plug from the cylinder shell.

A locking means is disclosed which may be operated by an angularly displaced tumbler. The single cut key is bitted angularly from the horizontal axis of the key.

This invention is set forth with particularity in the appended claims. The principles and characteristics of the invention, as well as other objects and advantages are revealed and discussed through the medium of the illustrative embodiments appearing in the specification and drawings which follow.

In the drawings:

FIG. 1 is a perspective view of an improved cylinder lock constructed in accordance with this invention;

FIG. 2 is a perspective view of the improved cylinder lock showing the different parts of the lock in separated positions;

FIG. 3 is a perspective view of the key constructed to operate the cylinder lock shown in FIGS. 1 and 2;

FIG. 4 is an enlarged view of a portion of the key plug assembly with tumblers and associated operating members and key;

FIG. 5 is a cutaway view of the key plug showing the tumblers in position with the key withdrawn;

FIG. 6 is a cutaway view of the key plug similar to FIG. 5, but with the tumblers in the position with the key engaged;

FIG. 7 is a longitudinal cross sectional view of the cylinder lock showing the key properly engaged in the cylinder lock;

FIG. 8 is a transverse cross sectional view of the cylinder lock with a proper insertion of a key to disengage and turn the key plug;

FIG. 9 is an enlarged perspective view of a portion of the key plug of a side bar cylinder lock;

FIG. 77ccenter We use this motion to cam the fence member towards the center of the key plug, forcing the projections or fence lugs against the tumbler members themselves. Therefore, when picking attempts are made, the tips or fence lugs of the fence member engage the true and false gates and surfaces in the periphery of the tumblers due to applied torque.

The engagement of the fence lugs of the fence member with the periphery of the tumblers makes it extremely difficult to move and position the tops of the tumblers and the bottoms of drivers to clear the shear line.

If picking has been accomplished so that the tumblers and drivers clear the shear line, it would now be necessary to rotate the tumblers themselves to their correct position so that their true gates would receive the fence lugs. To anyone familiar with this procedure of "lock picking," this necessary positioning of the tumblers and drivers to clear the shear line in combination with the rotational positioning of the tumblers to present their true gates to the fence lugs of the fence is highly improbable, if not impossible.

While the invention has been explained and described with the aid of particular embodiments thereof, it will be understood that the invention is not limited thereby and that many modifications retaining and utilizing the spirit thereof without departing essentially therefrom will occur to those skilled in the art in applying the invention to specic operating environments and conditions.

Claims

1. In a cylinder lock operated by a proper angularly bitted key, a cylinder shell, a key plug rotationally mounted in said cylinder shell to provide a shear line between said cylinder shell and said key plug, at least one tumbler mounted in said key plug to reciprocate and rotate therein as a whole, at least one driver associated with said tumbler positioned by the reciprocal movement of said tumbler upon engagement with the proper bitted key to clear the shear line, and a fence member blockingly associated with said tumbler and shaped so that the rotational positioning of said tumbler upon engagement with the proper bitted key allows said fence to clear the shear line.

2. The invention as claimed in claim 1 wherein said tumbler has a true gate parallel to the axis of said tumbler, and said fence member is blockingly associated with said true gate of said tumbler and shaped so that the rotational positioning of said tumbler with the proper angularly bitted key allows said fence member to clear the shear line.

3. The invention as claimed in claim 2 wherein means are provided for urging said fence member towards said cylinder shell, and a cammed cam surface on said fence member normally urged into engagement with said cylinder shell so that upon the proper rotational positioning of said true gates of said tumblers the fence member may be cammed out of engagement with said cylinder shell allowing said fence member to clear the shear line.

4. A cylinder lock and properly angularly bitted key comprising, a cylinder shell, a key plug rotationally mounted in said cylinder shell to form a shear line, a proper angularly bitted key, at least one tumbler reciprocally mounted in said key plug and rotatable therein about an axis, a true gate on said tumbler parallel to the axis of said tumbler, said tumbler and associated driver reciprocally positioned upon engagement with a properly bitted key to clear the shear line, a fence member, said fence member having a first cam surface thereon, a second cam surface on said cylinder shell adapted to cooperate with said first cam surface, means normally urging said fence member towards said cylinder shell so that said first cam surface normally engages said second cam surface, said tumbler shaped to be rotationally positioned upon engagement with said properly angularly bitted key to present said true gate to said fence member so that torque applied to said key plug will cam said fence out of engagement with said cylinder shell.

5. A cylinder lock having a cylinder shell, a key plug rotationally mounted in said cylinder shell, a key with bits formed so that it raises and lowers tumblers and causes rotation of tumblers, at least one tumbler as a whole capable of rotation and rseciprocal reciprocal movement in said key plug, and a fence member, said tumbler shaped in its rotatable position to either block or free said fence.

6. A cylinder lock, a cylinder shell, a key plug rotatably mounted in said cylinder shell to provide a shear line between said cylinder shell and said key plug, a key shaped with bits formed so that its raises and lowers tumblers and causes rotation of tumblers, at least one tumbler reciprocally mounted in said key plug and rotatably mounted therein about an axis, said tumbler having a first true gates thereof parallel to the axis of said tumbler, a second true gate perpendicular to the axis of said tumbler, and a fence member blockingly associated with said tumbler and shaped so that the rotation and reciprocal positioning of said tumbler upon engagement with the proper shaped key allows said fence to clear the shear line.

7. A key blade having a longitudinal axis of insertion, said key blade having a plurality of v-shaped cuts, at least one v-shaped cut perpendicular perpendicularly cut across the longitudinal axis of said key blade, and at least one v-shaped cut skew cut across the longitudinal axis of said key blade.

8. A lock, a key having a longitudinal axis of insertion, said key having a plurality of v-shaped cuts of variable depths, said v-shaped cuts perpendicular perpendicularly and skew cut across the longitudinal axis of said key, primary said lock including a primary locking means activated by the perpendicular and skew cuts of said v-shaped cuts.

9. A tumbler, said tumbler having a cylindrical body, a chisel shaped lower portion, and a true gate thereon parallel to the longitudinal axis of said tumbler, said true gate oriented to said chisel shaped lower portion.

10. The tumbler claimed in claim 9 wherein there is a second true gate thereon perpendicular perpendicular to the longitudinal axis of said tumbler.

11. A cylinder lock having a cylinder shell, a key plug rotationally mounted in said cylinder shell, a key with a plurality of bits including at least one skew cut bit formed so that it raises and lowers pin tumblers and causes rotation of said pin tumblers, at least one said pin tumbler as a whole capable of rotation and reciprocal movement about its own longitudinal axis in said key plug, and a fence member, said tumbler shaped in its rotational position to either block or free said fence.

12. A key blade as defined in claim 7 wherein there are a plurality of skew cuts.

13. A cylinder lock as in claim 5 wherein the key bits include skew cut bits.

14. A cylinder lock as in claim 5 wherein the tumblers are pin tumblers and their rotation and reciprocal movement is about their longitudinal axis.