GB2123474A - Improvements in or relating to security locks - Google Patents

Abstract

A lock comprises a housing and a core which can be removed from the housing by a forward pull on the operating key in intermediate positions between the locked and unlocked positions thereof. The core is provided with a series of spring loaded, key-engaging detainers (9) which are received within slots (11) to define the locked and unlocked positions and to permit withdrawal of the operating key in those positions. In intermediate positions therebetween, a pull on the operating key is transferred to the lock core which is held in the housing by a round section circlip received within a groove (6). A firm pull on the operating key will dislodge the circlip from the groove (6) and permit removal of the core from the housing. The core can similarly be relocated by a backwards push to re-engage the circlip in the groove (6). <IMAGE>

Description

SPECIFICATION Improvements in or relating to security locks This invention relates to security locks and in particular to fitted locks of the kind for securing the contents of office furnitue, personal lockers etc.

In securing the contents of general purpose office furniture there is a need for many locks which ensure, within the intended use of the furniture, adequate security without preventing resistance to forceable entry to that furniture in one guise or another; such furniture not normally being used to safeguard important and secret documents. For desk drawers and cabinets, often in frequent use, operating convenience and inexpensiveness can be more important than constructional design directed to thwarting forcible entry and it is the practice of costeffectiveness in providing security for everyday office and reiated furniture with which the present invention is concerned.

In the servicing of an office building, for example, it is common practice to issue office furniture keys and other keys such as locker keys to those persons who work in the building and to institute a support procedure whereby one or more master keys and a control key are held in the possession of authorised persons and the building services manager so that in the event of loss or mislaying of operating keys access can be gained to the contents of the furniture, lockers etc. Such a system needs and relies upon the call-up of replacement operating keys and although some lock manufacturers operate a voucher system for the expeditious supply of replacement keys this can entail unacceptable postal delay and administrative costs.

The extent of key loss and of lock maintenance has been appreciated in the servicing of large government and commercial estates and in response to the substantial administrative costs which have been identified certain manufacturing locksmiths have designed and promoted the sale of removable core locks. Removable core locks have several advantages, as follows: (i) Office furniture, lockers etc. can be supplied with lock housings only and need only be serviced with cores when in use or when security is required: it has been recognised that furniture is frequently provided with complete locks unnecessarily due to users ordering lockable equipment in anticipation of occasional or eventual need for locking.

(ii) Cores can be removed by the use of a control key, and likewise inserted, thus enabling replacement cores to be inserted without delay and without calling on the services of a locksmith.

(iii) Building services managers need only keep a small stock of replacement cores and the stockkeeping and administrative costs are minimal compared with a key replacement service: the provision of an on-site duplicate key service is costly and can be a security risk: as aforementioned supply of replacement keys by use of a voucher scheme promoted by the manufacturer entails delay and overhead costs.

(iv) Each individual can be issued with a lock core and keys as a personal possession and can relocate with the issued core and keys as in the case, for example, of office personnel moving location from time to time.

(v) The association of specific cores and keys with particular items of furniture at the manufacturing stage is obviated, simplifying stock control and the keeping of records and introducing a flexible system of security control.

In one design of known removable core lock, comprising a lock housing, a removable core and a locking tongue (sometimes referred to as a "locking cam") the locking tongue is mounted on the inner end of the lock core and is rotated between the open and closed (or unlocked and locked) positions by the twist of a lock key in rotating the lock core: hence the core can only be removed when the lock is in the open position and access can be gained to the rear of the lock to detach the locking tongue.In another known design the core can be demounted from the front of the lock and mounted therein by the use of a control key and movement of the key in the core through demounting and mounting motions, each core in the core system controlled by the control key having the control key combination, and having a locking lug which is caused to protrude laterally into a recess in the lock housing when the control key is moved through the mounting motion and to withdraw from the recess into the core when the key is moved through the demounting motion.

The present invention is concerned with locks comprising a lock housing, a removable core and a locking device; and in particular, although not solely, with removable core locks suitable for fitting, for example, to the doors of cupboards, office cabinets, lockers etc. wherein the locking device is frequently, although not necessarily, a locking tongue, as in the afore-disclosed one design, which is removably mounted on the inner or rear side of a lock. In another arrangement, for example, the locking device can comprise a lever mechanism movable about pivots to operate locking bolts the lever mechanism being actuated by movement of a cam secured to the rear side of a lock in the same manner as a locking tongue.

Other interior locking devices which could be actuated by rotation of the lock core will be known to locksmiths skilled in the art of lock design.

However the invention is not limited to removable core locks of the kind having such interior locking devices and has application to other designs such as where the locking device comprises an internal tumbler mechanism and the shackle of a padiock or the bolt mechanism of mortice or rim locks (e.g.

Yale (Registered Trade Mark) type door locks); movement of the tumbler mechanism actuating the shackle or bolt mechanism.

The invention is directed to an improved design of removable core lock which mitigates at least some of the drawbacks and requirements of the known designs and provides a simple and flexible method for the forward demounting and reinsertion of cores with matching operating keys without, in particular, the need for access to the rear of the lock or the use of a control key. A preferred feature of the invention enables a core to be forcibly removed from the front in the event of key loss, causing damage to the core and thus preventing its re-use, but without sustaining damage to the lock housing, so that a replacement core can be readily fitted.

Accordingly the present invention provides a lock comprising a lock housing and a matching removable core fitted therein and constrained in the fitted position by restraining means, said core having a series of spring-loaded key-engaging detainers adapted to engage an operating key insertable in the core such that the detainers are within the body of the core and engaging the shank of the key when the key is positioned in the core and protrude therefrom when the key is withdrawn, said housing having internal detainer slots extending longitudinally in positions to allow the detainers to protrude therein when the lock is in the open and closed positions and in which positions the operating key can be inserted and withdrawn, wherein the restraining means exercises a restraint which can be overcome, to permit removal of the core, by a forward pull on the core applied to the inserted operating key in positions of the core where the detainers are not free to move and can be imposed, to constrain the core in the fitted position, by a backwards push to engage the restraining means.

The restraining means may be a resilient device responding to forward pulls and backwards pushes to release and engage the removable core respectively. Preferably the restraining means is a circlip located in an internal groove in the housing and protruding inwardly therefrom to engage the removable core and to constrain the core in the fitted position, by locating in a peripheral groove provided therein.

In the fitted position within the lock housing the removable core may be interlocked with a coreinterlocking member retained within the housing and freely rotatable therein, said core-interlocking member being adapted to engage a locking device, whereby rotational movement of the core by twist of an inserted key causes motion to be applied to the locking device. Generally it is preferred to design the removable core and the core-interlocking member so that a mechanical interlock is provided: conveniently a diametral slot is formed in one of the two parts to mate with a protruding tongue formed on the other part.

In the present invention the term 'locking device' means a locking tongue or any locking mechanism or combination of mechanisms, such as the combination of a tumbler mechanism and a bolt mechanism, actuable by rotation of a lock core or a lock core in conjunction with a coreinterlocking member.

The removable core and the lock housing may be constructed for removal of the core from the housing by forcible extraction with an extractor tool, in the absence of a key, without incurring damage to the housing. The removable core in such a construction may have a key slot suitable for receiving the threaded spigot of an extractor tool and for engaging therewith and the detainer slots in the housing may each have a strengthened shoulder obstructing the front end thereof so that on forcible extraction of the core the protruding detainers are destructively damaged. The strengthened shoulder may be provided by a hardened circlip abutting the inner side of a shoulder formed as part of the housing and obstructing the front end of each detainer slot.

The use of an extractor tool arises in those instances where there has been a loss of the operating keys and the support procedure does not include the provision of a master key: where the service procedure provides a master key the lock may be opened and the core removed, as in the aforedescribed manner with an operating key, the lock being rendered serviceable by the issue of a replacement core with operating keys.A suitable core extractor tool is one having a hardened threaded spigot which may be screwed into the core along the key slot the core then being extracted by operating the extractor mechanism: the extraction motion desirably causes the detainers protruding into the detainer slots to be bent as they are forced over the strengthened shoulders closing off the detainer slots: in this way damage is confined to the core and the lock housing remains serviceable for use with a replacement core.

The invention will now be described, by way of example, with reference to the accompanying drawings wherein: Figure 1 is a sectional elevation of a lock housing taken through opposing detainer slots Figure 2 is a sectional view on the line A-A of Fig. 1 Figure 3 is a side view of a removable core showing the core detainers Figure 4 is a side view of a core-interlocking member positionable in, and rotatable within, the lock housing shown in Fig. 1 Figure 5 is an end view of the core-interlocking member shown in Fig. 4 Figure 6 is a side view of the removable core shown in Fig. 3, with the core rotated through 900 Figure 7 is a plan view, viewed from above, of the core-interlocking member shown in Fig. 4 Figure 8 is a perspective view of the removable core illustrating the core detainers Figure 9 is a sectional elevation through the removable core and Figure 10 is a cross-sectional elevation taken along the line B-B of Fig. 9 Figs. 1 and 3 illustrate major parts of a removable core lock comprising a lock housing (Fig. 1) and a matching removable core (Fig. 3).

In the fitted position within the housing the removable core is constrained in that position by restraining means in the form of a resilient roundsection steel circlip (not shown) which is located in an internal groove 7 in the housing and protrudes inwardly therefrom to engage in a peripheral groove 6 provided in the core. The core has a series of spring-loaded key-engaging detainers 9 (Fig. 3) which engage with an operating key insertable in the core such that the detainers 9 are within the body of the core and engaging the shank of the key when the key is positioned in the core and protrude from the core when the key is withdrawn. The mechanical construction and operation of the core detainers - in conjunction with an operating key - is explained in detail hereafter. The lock housing (Fig.

1) has internal detainer slots 11 (Fig. 2) extending longitudinally in positions in the wall of the housing to allow the detainers 9 to protrude therein when the lock is in the open and closed positions and in which positions the operating key can be inserted and withdrawn. The detainer slots 11 are diametrically opposite and detainers 9 protrude therein from the two corresponding sides of the core.The core is removed from the housing by inserting the operating key and moving the key slot to any position between the 'open' and 'closed' positions, in which position movement of the key in and out of the slot is impeded by the engaging detainers 9, and applying a forward pull to the operating key, corresponding to a forward pull on the core by reaction through the detainers 9, of a magnitude to overcome lodgment of the round-section circlip in groove 6 (Fig. 3) and to force the circlip outward into groove 7: groove 7 is machined to a depth to readily accommodate the circlip when it is expanded outwardly, and the circlip has both a clip diameter and a section size enabling the clip to both lodge in groove 7 and to protrude inwardly therefrom when unstressed: it is the inward protrusion of the circlip that fits into groove 6 of the core.When the circlip is caused to ride out of groove 6, by the forward pull, and to expand into groove 7 the removable core is free to nove out of the housing. The core or another matching core can be inserted in the fitted position within the housing by inserting an operating key in the core and applying a backwards push to the core via the key to engage the circlip and locate it in groove 6. Conveniently tongue 3 (Fig. 3), the function of which is described below, is provided with a chamfered shoulder 8 which engages the circlip as the core is pushed into the housing and causes the circlip to ride up the shoulder thereby expanding the clip and allowing it to slot into groove 6.

In the fitted position within the lock housing the removable core is interlocked with a coreinterlocking member (Fig. 4) which is retained within the housing and freely rotatable therein.

The core-interlocking member is retained within the housing by a square-section steel circlip (not shown) located within annular grooves 1, 2. As in the instance of the prior-described use of the round-section circlip, the square-section circlip lodges in groove 1 of the housing and engages groove 2 of the core-interlocking member. The removable core (Fig. 3) is provided with a tongue 3 which protrudes into and engages a diametral slot 4 formed in the forward facing side of the interlocking member in the retained position, thereby providing a mechanical interlock when the core is in the fitted position: by virtue of the interlock rotational movement of the core by twist of a key inserted in the core causes the movement to be imposed on the core-interlocking member, which upon removal of the core from the lock remains in situ in the housing.In applying a backwards push to locate the removable core in the fitted position it will be apparent that it is necessary to align the tongue 3 with the slot 4.

The core-interlocking member has a squareshaped head 5 (Figs. 4, 5) formed on the rearward facing side, in the retained position, the head 5 protruding from the rear of the housing and engaging with a locking tongue (not shown): the locking tongue has a shaped slot formed at one end thereof, the slot providing an engaging fit with the protruding head, and the tongue being anchored in position on the protruding head with an end screw and spring washer (not shown).

Rotary movement applied to the interlocking member thereby causes the locking tongue to move between open and closed positions. The core-interlocking member has a travel limiter 13 engaging in a part-circular recess 1 8 machined in the lock housing, the travel limiter in abutting the recess ends serving to register the open and closed positions of the lock and the location of the detainer slots 11, and thereby indicate the two positions at which the key may be withdrawn in normal usage.

Figs. 3, 8, 9 and 10 illustrate the construction of the removable core. The core houses a series of detainers 9 each of which is spring-loaded by a spring 14 and under the influence of its spring each detainer protrudes from the core, as illustrated in Figs. 8, 9 and 10. The detainers protrude to an equal extent from two sides of the core and can do so when the detainers are aligned with and registered within the detainer slots 11 in the lock housing corresponding to "open" and "closed" lock positions. In these positions an operating key can be withdrawn from the core the outward movement of the detainers 9 into slots 11 releasing the constraints on the shank of the key. The slot 1 5 in each detainer 9 accommodates the key shank and is so positioned within its respective detainer to conform with the selected combination of the lock, which combination is that cut on the key shank. When the key is inserted through the slots the detainers protruding from two sides of the core are withdrawn into the body of the core and the springs 1 4 are compressed by inward movement of the lugs 1 6 attached to detainers 9. The detainers have sufficient free movement to respond to all the shaped configurations on the key shank so that when the key is fully inserted the springs 14 have reasserted the detainers 9 and the detainers 9 are pressed against the shank profile.The slots 1 5 in the detainers 9 are so located that in the "key-in" position the detainer ends are all flush with the body of the core. In removing a core from a lock housing in normal usage insertion of an operating key in the "open" or "ciosed" positions retracts the detainers into the core such that the detainer ends are then flush with the core body: the key slot can then be moved to an intermediate position between "open" and "closed" and a pull applied to the key to overcome the restraining circlip, as aforedescribed: in applying a pull the shank of the key will act to force some of the detainers radially outwards from the core, by virtue of the key profile, but in the intermediate positions the outward movement is restrained by the wall of the lock housing; hence movement of the key shank out of the core is arrested and it is the anchoring of the shank in the core that enables a pull to be applied to overcome the restraining circlip: in addition there is a small frictional restraint caused by the ends of the detainers being forced outwards against the housing wall and, conveniently, once the circlip has been overcome the further removal of the core can be facilitated if the forward pull is relaxed somewhat to ease the frictional restraint.

In the absence or loss of operating keys the lock may be opened and the core removed with a master key where the office or service management provides this back-up facility, whereupon a replacement core and operating keys can be issued. Alternatively, where there is no master key provision the core can be removed with a core extractor tool and the lock housing (Fig. 1) is suitably strengthened to withstand forcible extraction of the core without damage to the housing being incurred.The housing is formed with internal shoulders 1 7 obstructing the front ends of detainer slots 11 and these are strengthened by the provision of a hardened square section circlip (not shown) abutting the innerside of each shoulder and fitting in groove 1 2. The key slot is suitable for receiving the threaded spigot of an extractor tool and upon engagement of the spigot in the slot the extractor mechanism can be operated to forcibly withdraw the core from the housing. Forcible extraction causes the detainers to be bent as the protruding ends are forced over the hardened circlip: the destructively damaged core is discarded and a replacement core with keys issued for use with the undamaged housing. The lock housing and the body of the removable core is made from MAZAK alloy, a zinc-diecasting material, and it is usual practice to make the structural parts of a lock with such a material: it is therefore essential to protect the slot obstructing shoulders 1 7 with some form of hardened steel reinforcement so that when the ends of the steel detainers are forced over the shoulders 1 7 it is the detainers that are bent and the shoulders are undamaged.

Figs. 3, 8, 9 and 10 illustrate one form of core construction suitable for use in the invention but other forms of detainer design will be known to locksmiths skilled in the art of core construction and these other designs may be used in removable core locks according to the present invention.

Claims (10)

1. A lock comprising a lock housing and a matching removable core fitted therein and constrained in the fitted position by restraining means, said core having a series of spring-loaded key-engaging detainers adapted to engage an operating key insertable in the core such that the detainers are within the body of the core and engaging the shank of the key when the key is positioned in the core and protrude therefrom when the key is withdrawn, said housing having internal detainer slots extending longitudinally in positions to allow the detainers to protrude therein when the lock is in the open and closed positions and in which positions the operating key can be inserted and withdrawn, wherein the restraining means exercises a restraint which can be overcome, to permit removal of the core, by a forward pull on the core applied to the inserted operating key in positions of the core where the detainers are not free to move and can be imposed, to constrain the core in the fitted position, by a backwards push to engage the restraining means.

2. A lock according to claim 1 wherein the restraining means is a resilient device responding to forward pulls and backward pushes to release and engage the removable cores respectively.

3. A lock according to claim 2 wherein the restraining means is a circlip located in an internal groove in the housing and protruding inwardly therefrom to engage the removable core and to constrain the core in the fitted position by locating in a peripheral groove provided therein.

4. A lock as claimed in any of claims 1 to 3 in which the removable core in the fitted position within the lock housing is interlocked with a coreinterlocking member retained within the housing and freely rotatable therein, said core-interlocking member being adapted to engage a locking device (as hereinbefore defined) whereby rotational movement of the core actuates the locking device.

5. A lock as claimed in claim 4 wherein the removable core is mechanically interlocked with the core-interlocking member.

6. A lock as claimed in any preceding claim in which the removable core and the lock housing are constructed for removal of the core from the housing by forcible extraction with an extractor tool, in the absence of a key, without incurring damage to the housing.

7. A lock as claimed in claim 6 in which the detainer slots in the housing each have a strengthened shoulder obstructing the front end thereof.

8. A lock as claimed in claim 7 in which the removable core has a key slot suitable for receiving the threaded spigot of an extractor tool and for engaging therewith so that on forcible extraction of the core the protruding detainers are bent and destructively damaged in passing over the strengthened shoulders.

9. A lock as claimed in either claim 7 or 8 in which the strengthened shoulder is provided by a hardened circlip abutting the inner side of a shoulder formed as part of the housing and obstructing the front end of each detainer slot.

10. A lock substantially as hereinbefore described with reference to the accompanying drawings.