US3597948A

US3597948A - Lock cylinder assembly

Info

Publication number: US3597948A
Authority: US
Inventors: Theodore H Johnstone
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1969-01-14
Filing date: 1969-01-14
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10

Abstract

A core of a conventional tumbler-type lock cylinder assembly includes an additional rib which receives only an additional groove in the free end of the bitted portion of the key to increase the number of usable lock combinations.

Description

United States Patent [72] Inventor Theodore H. Johnstoue New Baltimore, Mich. [211 AppLNo. 791,112 [22] Filed Jan. 14, 1969 I45] Patented Aug. 10, 1971 [7 3] Assignee General Motors Corporation Detroit, Mich.

[541 LOCK CYLINDER ASSEMBLY 1 Claim, 4 Drawing Figs.

[52] US. Cl 1. 70/364 R, 70/406, 70/453 [51] Int. Cl E051) 15/08, 1305b 19/06 [50] Field of Search 70/364, 364 A, 375, 382, 405, 406, 419, 420, 421, 453, 454, 403, 404, 407

[56] References Cited UNITED STATES PATENTS 246,438 8/1881 Woolaston et a1. 70/363 Primary Examiner-Jan A. Calvert Assistant ExaminerRobert L. Wolfe Attorneys-E. W. Christen and Herbert Furman Bod ge Spain Taylor FOREIGN PATENTS Switzerland France tions.

LOCK CYLINDER ASSEMBLY This invention relates to lock cylinder assemblies and more particularly to a lock cylinder assembly having an increased number oflock combinations. I i

The number of lock combinations which normally can be obtained from a tumbler-type lock is affected by the number of tumblers included in the lock. Generally the number of theoretical combinations is much greater than the number of usable combinations.

In order to increase the number ofcombinations without increasing the number of tumblers, it is conventional to provide a ribbed gate in the core and grooves in the key which must mate with the ribs of the gate before the key can be inserted in the core to properly locate the tumblers in their unlocked position. Due to space and manufacturing limitations, the number of such ribs and grooves is limited so that the increase in number oflock combinations is likewise limited.

The lock cylinder assembly of this invention increases the number of lock combinations by having an additional rib within the core remote from the ribbed gate and receiving an additional groove in the leading end of the bitted portion of the key when the key is fully inserted within the core. The core rib is unaligned with any other core rib and likewise the key groove is unaligned with any other key groove so that only a properly grooved key can be fully inserted in order to locate the tumblers in their unlocked position. By varying the location of the interfitting additional rib and groove, in combination with varying the location of the ribs on the gate and grooves on the key, an increase in the number of possible lock combinations can be obtained within the normal manufacturing and space limitations By locating the additional rib remote from the gate and by locating the groove in the leading end of the bitted portion of the key, it is impossible for an imroperly coded key to move all of the tumblers to unlocked position by partial insertion of the key.

The primary object of this invention is to provide a lock cylinder assembly having an increased number of lock combinations. Another object of this invention is to provide a lock cylinder assembly having an additional rib within the core remote from the gate and receiving an additional groove in the leading end of the bitted portion of the key, both unaligned with any other ribs and grooves, to thereby provide an increase in the number of usable lock combinations.

These and other objects of the invention will be readily apparent from the following specification and drawings wherein:

FIG. I is a partially cutaway view of a lock cylinder assembly according to this invention;

FIG. 2 is a sectional view taken generally along the plane indicated by line 2-2 of FIG. 1;

FIG. 3 is a view taken generally along the plane indicated by line 3-3 of FIG. 1; and

FIG. 4 is a view similar to FIG. I showing the assembly with the key withdrawn.

Referring now to FIG. 1 of the drawings, the lock cylinder assembly of this invention includes a conventional side bar lock cylinder 10 having a core 12 mounting a plurality of shiftable tumblers 14, best shown in FIG. 2, each of which includes a notch I6. When the notches 16 are aligned upon insertion ofa properly coded key, a side bar 18 moves inwardly of the core to permit the core to rotate within the outer case 20 of the assembly. This is conventional in currently used side bar lock cylinder assemblies.

The key 22 includes a bitted portion 24 which, when inserted within the core, locates the tumblers 14 in their unlocked position to align the notches I6. In order to increase the number of lock combinations, the core 12 includes a conventional gate 26 provided with one or more ribs 28, and the key 22 includes respective grooves 30 on the bitted portion 24 which slide relative to the ribs when the key is inserted. By varying the location of the ribs 28 and grooves 30, the number ofloek combinations is increased.

Due to space and manufacturing limitations, there are only a limited number of possible locations of the ribs 28 and grooves 30 so that the number of lock combinations can only be increased by a limited amount.

In accordance with this invention, the core 12 includes an additional rib 32 on a wall of a recess 34 thereof which receives the leading end of the bitted portion of the key when the key is inserted. An additional groove 36 on a wall of the key receives the additional rib 32. By varying the location of the rib 32 and groove 36, the number of possible lock combinations is increased.

With reference to FIGS. 2 and 3, it can be seen that the rib 32 is unaligned with any other rib in the core 12 and likewise the groove 36 is unaligned with any other groove in the particular wall of the key.

Thus this invention provides a lock cylinder assembly having an increased number of lock combinations without increasing the number of tumblers.

'Iclaim:

l. A lock cylinder assembly including a core mounting a plurality of keylocatable tumblers and defining a slot, a key having a flattened bitted portion receivable within the slot wherein the lateral sides of the bitted portion include grooves Y for receiving ribs fixed with respect to the core and extending axially thereof adjacent the opening of the slot, an additional lateral rib fixed with respect to the core adjacent the end of the slot remote from the opening thereof, the additional lateral rib extending axially of the core for a limited distance with respect to the bitted portion when inserted within the slot, and an additional lateral groove at the free end of the bitted portion extending for such limited distance and receiving the additional lateral rib when the bitted portion is inserted within the slot, the additional lateral rib and the additional lateral groove being unaligned with any rib or groove adjacent the opening of the slot.

Claims

1. A lock cylinder assembly including a core mounting a plurality of key-locatable tumblers and defining a slot, a key having a flattened bitted portion receivable within the slot wherein the lateral sides of the bitted portion include grooves for receiving ribs fixed with respect to the core and extending axially thereof adjacent the opening of the slot, an additional lateral rib fixed with respect to the core adjacent the end of the slot remote from the opening thereof, the additional lateral rib extending axially of the core for a limited distance with respect to the bitted portion when inserted within the slot, and an additional lateral groove at the free end of the bitted portion extending for such limited distance and receiving the additional lateral rib when the bitted portion is inserted within the slot, the additional lateral rib and the additional lateral groove being unalined with any rib or groove adjacent the opening of the slot.