Theft Deterent Lock

A serious problem currently exists with respect to the ease by which unauthorized persons can sometimes gain access to secured premises which are protected by certain cylinder or tumbler type locks. Heretofore, such cylinder or tumbler type locks are generally installed on a door so that the face of the cylinder is disposed to the outside of the door and which cylinder is secured by screw type fasteners to the door from the back side of the door. Would be burglars and/or authorized persons have developed a technique whereby such locks can be easily defeated thereby permitting such persons to gain access to the premises secured thereby. The technique developed to defeat such lock installations is that the would be thief will grip the face plate of the cylinder extending to the front of the door with a suitable gripping tool and by applying a torque or turning movement back and forth will shear the screws or fasteners securing the lock cylinder to the door. Once the screws securing the lock cylinder to the door have been sheared, the thief can then simply pull the entire cylinder out of the door and thus defeat the lock.

An object of this invention is to provide a deterent to a tumbler or cylinder type lock which prohibits a would be thief from shearing the fasteners by which the lock is secured to a door and thereby prohibiting such person from defeating the lock.

Another object resides in the provision whereby a cylinder or tumbler type lock can be rendered theft resistant in a relatively simple and expedient manner.

Another object resides in the provision whereby a known type of cylinder or tumbler type lock can be rendered theft proof without altering the construction of the locking mechanism per se of a given lock.

Another object resides in the provision of a theft deterent lock which can be readily assembled and installed with conventional lock mechanisms and applied to a door in a conventional manner.

The foregoing objects and other features and advantages are attained by a lock assembly which is rendered theft proof by the inclusion of a protective sleeve which circumscribes the lock cylinder so as to be rendered readily rotatable relative thereto. The protective sleeve includes a face plate arranged to extend in the plane of the door. The protective sleeve is extended into a bore or lock opening formed in the door and provides the housing for the lock cylinder or tumbler. A lock nut is threaded to the remote end of the sleeve to secure the lock cylinder within the protective sleeve. The arrangement is such that the protective sleeve is mounted to rotate relative to the lock cylinder when a torque or turning movement is applied to the exposed face of the sleeve. The lock is secured to the door or to the back plate of the latch component of the lock by suitable fasteners such as screws. With the protective sleeve rotatably mounted relative to the lock cylinder a turning or torque movement applied to the sleeve will merely result in the protective sleeve being rotated relative to the lock cylinder, thus preventing the torque force being transmitted to the screw fasteners securing the lock to the door. As a result, a would be thief cannot shear the fasteners which secure the lock to the door in the manner heretofore developed by such persons to gain unauthorized access to a secured premise. The lock thus defined can be applied or adapted to any door thickness by the application of appropriate door spacers.

A feature of this invention resides in the provision of a protective sleeve circumscribing the lock cylinder so as to be rendered rotatable relative thereto.

Another feature resides in that the lock assembly including the protective sleeve can be fitted to any desired door size by the utilization of appropriate spacers.

Another feature resides in the provision that the protective sleeve can be readily applied to existing locks simply and quickly.

Another feature resides in the provision that the theft deterent lock is relatively simple in construction and positive in operation, and is relatively inexpensive to fabricate.

Other features and advantages will become more readily apparent when considered in view of the drawings and specifications in which:

FIG. 1 is a cross sectional view of a lock assembly embodying the present invention.

FIG. 2 is an enlarged front view of the lock assembly of FIG. 1.

FIG. 3 is an enlarged rear end view of the rotatable sleeve with lock mechanism in place.

FIG. 4 is a detail rear view of the adaptor for the lock mechanism.

FIG. 5 is a top view of FIG. 4.

FIG. 6 is a side view of FIG. 4.

FIG. 7 is a sectional view taken along line 7--7 of FIG. 4.

FIG. 8 is a detail view of the back plate of the latch mechanism.

FIG. 9 is a fragmentary sectional view of a modified form of the invention.

FIG. 10 is a sectional side view of a modified embodiment.

FIG. 11 is a front view of the lock deterent assembly of FIG. 10.

FIG. 12 is a rear view of the lock deterent assembly of FIG. 10.

FIG. 13 is an exploded perspective view of the component parts of the block deterent assembly of FIG. 10.

Referring to the drawings there is shown in FIG. 1 a tumbler or cylinder type lock 10 embodying the present invention. The lock assembly 10 is of the cylinder type locks which are installed in a bore or opening 11 which extends through a door or closure 12 and to which the lock is secured. The lock assembly 10 comprises a protective sleeve 13 which includes a face plate 13A and a connected sleeve body 13B. It will be noted that the sleeve body 13B has an external diameter by which it can be readily fitted into the bore or opening 11 in the door 12. As shown, the face 13A has a diameter greater than that of the opening so that the outer periphery of the face plate 13A defines a flange by which it abutts against the plane of the door 12.

Disposed within the sleeve body 13B is the lock cylinder means 14. It will be understood that the lock cylinder means 14 may comprise the lock mechanism of known construction per se or it may comprise an adaptor for receiving a particular type of lock mechanism. As there are several known manufacturers of lock mechanisms, the illustrated embodyment discloses an adaptor 15 which is fitted into the sleeve body 13B and which adaptor 15 is arranged to receive a particular lock cylinder or mechanism 14A which includes the tumblers or cylinders of the lock mechanism per se.

The lock mechanism 14A per se includes a housing which has a keyway or key slot 17 for receiving a key 18 and the tumblers or cylinders associated therewith (which are not illustrated as such lock mechanism are well known). Associated with the lock mechanism 14A is the turn shaft 19 which connects to the latch mechanism 20 for effecting the operation of the locking latch when the key is turned.

The face plate 13A is provided with an opening 16 which is disposed in alignment with the keyway 17. The remote end of the sleeve body 13B is internally threaded at 25 for receiving a lock nut or ring 21 by which the lock mechanism 14A is secured within the sleeve body 13B.

The arrangement is such that the protective sleeve 13B and its associated lock ring or nut 21, when fitted to the door is free to rotate relative to the lock mechanism 14A or adaptor 15; in the event an applied turning movement is imparted to the front flange or plate 13A.

As shown, the lock assembly 10 described is secured to the door by a plurality screw or bolt type fastener 22A which are threaded into tapped holes 22 formed in the adaptor body 15. In the illustrated embodiment, four such tapped holes 22 are noted in the adaptor body 15. The back plate 23 of the latch assembly 24 is provided with appropriate fasteners holes 23A so that the securing fasteners 22A can be extended through the back plate 23 to secure the lock assembly to the door.

In accordance with this invention the back plate 23 is formed of a metal plate having a plurality of tapped or threaded holes or notches 23B. It will be noted that the tapped or threaded holes or notches 23B are disposed in aligment with the holes formed in the latch housing through which the screws or fasteners 27 are extended. The arrangement is such that the latch housing 24 connected to the inside of the door can be positively secured to the metallic latch plate 23 rather than being screwed directly to the door. With the construction described, the lock assembly 10 can be securely fastened to the door without having to have the screw threaded into the surface of the door.

As best seen, in FIG. 4 to 7, the adaptor 15 comprises a component part having a body portion which is sized to be received within the tubular sleeve 13B. The adaptor body is provided with a reduced rear end portion 15A which has extending parallel to its longitudinal axis a plurality of tapped holes 22. The adaptor body is provided with a longitudinal extending bore 15B communicating with a longitudinal extending slot 15C. Thus, the adaptor is shaped to accommodate the locking mechanism 14A which includes the keyway 17 and associated lock tumblers or cylinders. The keyway portion of the lock mechanism is snuggly received in the bore 15B and the tumbler portion of the lock mechanism 14A is received in slot 15C. If desired, a washer 30 is fitted adjacent to the back of the lock assembly between it and the back plate 23.

In order to adapt the described lock assembly to a door of given thickness a plurality of shims or spacers are interposed in contiguous relationship to the rear portion of the lock assembly. Several of such spacers 31 are shown in FIG. 1. Spacers 31 are utilized in the event that the door or closure thickness is greater than the length of the tubular sleeve 13B. It will be understood that each spacer 31 is provided with an opening 31A therein through which the lock shaft 19 is extended. The respective spacers 31 are also provided with a series of holes 31B through which the fasteners 27 are extended to secure the adaptor body to the back plate 23 of the latch assembly. Thus, one or more spacers 31 may be added to the end of the lock assembly as may be necessary to take up the difference between the length of the sleeve 13B and the depth of the hole 11 formed in the door which is equal to the door thickness.

In the event that the thickness of the door 12 is less than the length of the sleeve body 13A, a plurality of spacer rings 32 are disposed between the front face 13A of the sleeve 13 and the front of the door 12 as seen in FIG. 9. The number of spacer 32 rings required will depend upon the size or width of the spacer rings 32 and the difference between the door thickness and the length of the sleeve body 13B.

To predeterminately position the sleeve 13 relative to the adaptor or cylinder lock assembly so as to maintain the opening 16 in the face plate 13A in alignment with the keyway 17, the sleeve 13 is pinned or releasably secured to the adaptor 15 by a frangible shear pin 33. The arrangement is such that the frangible pin 33 is sufficient to maintain the sleeve 13 fixed to the adaptor 15, but which pin 33 will shear when a predetermined amount of torque is applied to the sleeve 13 when it is being tampered with by an unauthorized person.

It will be understood that the sleeve including its face plate 13A may be formed of a hardened metal such as hard steel which will resist drilling.

From the foregoing description, it will be apparent that the utilization of sleeve 13 which is rotatably disposed relative to the lock cylinder or assembly 14A or its adaptor 15 will effectively defeat a trespassers' technique of shearing the screws or fasteners 22A by a twisting or torque face applied to the face plate of such cylinder or tumbler type locks.

FIGS. 10 to 13 illustrate a modified form of the invention. In this embodiment the theft deterent lock assembly or mechanism 40 includes a sleeve 41 having a cylindrical sleeve body 41A adapted, receive or house the lock mechanism 42. The lock mechanism as hereinbefore described comprises a conventional cylindrical or tumbler type lock mechanism of well known construction. Connected to the front end of the sleeve 41 is a face plate 41B having a radially extending flange portion 41C which is adapted to abutt in the plane of a door or closure 43 on one side thereof. The face plate 41B is provided with an opening 44 which is disposed in alignment with the key slot 45 of the lock mechanism 42. As shown, the rear or other end of the sleeve body 41B is provided with an internal threaded portion 45. It will be understood that the external diameter of the sleeve body 41A is sized so as to be received in a bore or opening 43A formed in the door 43. The arrangement is such that the lock cylinder or mechanism 42 is fitted within the sleeve body so that it may rotate relative to the lock mechanism 42 if a turning or twisting moment is imparted to the face plate 41b by a would be thief, as hereinbefore described. To further deter from imparting a torque moment onto the face plate 41B, the circumferential portion of the face plate 41B may be tapered or inclined as best seen in FIG. 10. If desired, the sleeve body 41A may be provided with a tapped hole 46 for receiving a set screw 47 for releaseably holding the lock cylinder 42 in place within the sleeve body 41A.

Mated to the rear end of the sleeve body 41A to retain the lock cylinder 41 in place is a retainer nut 48. As shown, the retainer nut 48 has a threaded portion 48A which is adapted to be threaded or mated to the threaded end 45 of the sleeve body. The retainer nut 48 is also provided with a radial flange portion 48B which is adapted to abutt in the plane of the door 43 on the opposite side thereof. In the illustrated embodiment a mounting plate 49 is secured to the door, and which mounting plate is provided with a hole 49A for receiving the nut 48A.

In the foregoing description, it will be noted that the component parts can be readily assembled by fitting the sleeve 41 with the lock mechanism in place therein into the door opening 43A from one side thereof, and fitting and mating the retainer nut 48 thereto from the other side of the door 43. The retainer nut 48 is then secured to the door by suitable fasteners such as screws or bolts 50 that thread into tapped holes 51 formed in the mounting plate 49, or if no mounting plate is used, into the door 43.

In accordance with this invention, a coupling means is provided to couple the sleeve body 41A to the nut 48A so that both can turn in unison in the event a turning moment is imparted to the face plate 41B of the sleeve 41. As shown, the internal portion of the sleeve body 41A is provided with one or more keyways 52 extending longitudinally. The nut 48A is also provided with a complementary keyway 53 which when mated to the sleeve keyway 52 define a channel for receiving a pin 54. It will be understood that the keyways 52,53 and associated pin 54 may be either round or polygonical in cross section. With the pins 54 inserted in the channel defined by the complementary keyways 52 and 53 the sleeve 41 and nut 48 are coupled to rotate in unison when a torque is applied to the face plate.

Bolted to the mounting plate is the latch mechanism 56 which contains the latch bolt (not shown) and which receives the turn shaft 59, in a well known manner. As shown in FIG. 10, suitable bolts 57 secure the latch mechanism 56 to the mounting plate or door.

In operation, when a would be thief attempts to apply the technique of twisting or turning the face plate 41B of the lock assembly in an effort to defeat the lock, as hereinbefore described, the sleeve and nut coupled thereto will be turned in unison accordingly. As best, such turning moment may effect the shearing of the fasteners 50 which secure the nut to the mounting plate 49 or door 43. However, with the construction described, the would be thief cannot remove the sleeve 41 or lock mechanism 42 from the door. Thus, the security afforded by the lock assembly is maintained in tact. Because of the flange portion 41C of the sleeve 41 and the flange portion 48B of the retainer 48 sandwiches the door therebetween, it will be noted that the lock assembly cannot be pushed in or pulled out, even if one is successful in shearing the fasteners 50.

While the invention has been described with respect to a specific embodiment of the invention, it will be readily understood and appreciated that variations and modifications may be made without departing from the spirit or scope of the invention.