GB2050486A - Lock with Door-opening Restrictor - Google Patents

Abstract

A deadlock for a door and like apertures to secure the door against unauthorised entry while permitting easy and frequent authorised entry. The deadlock includes a deadbolt (DB) extendable to engage loosely in a bolt box or socket (BB). The bolt is biassed by spring (BS) to be retracted when the door is open. A magnet (PM) on the door frame acts as an armature (AR) when the door is near to the frame to overcome the bias and extend the bolt to engage the socket and secure the door. The magnet can also pull the door in to align the bolt with the bolt box and keep the door closely seated in the frame. An electromagnet (EM) wound on the armature can be energised to overcome the permanent magnet and allow the bias to retract the bolt or can repel the bolt releasing the door. The bias and magnets can act on the bolt via a swing link (LK) and operating quadrant (OQ). Remote control via switches, which may be key operated, is possible. <IMAGE>

Description

SPECIFICATION Deadlocks This invention relates to a deadlock for a door and like apertures and closures requiring secure bolting of the closure while permitting easy access when authorised.

Buildings, such as blocks of flats, which many different individuals require to enter from time to time provide a considerable security problem. If unrestricted access is allowed vandalism and other misuse of the internal communal areas can occur. If access is controlled by an attendant such as a porter the cost and difficulty of finding sufficient reliable staff is so great that few organisations can afford it. A compromise often adopted is to provide a normally locked door and an electromagnetically openable lock box and a telephone system between the door and the occupants of the building. To obtain access without a key a person requests of an occupant, via the telephone system, that the lock box be released by a control associated with the occupant's telephone.

However such releasable lock box systems are not always proof against forced entry. The lock bolt can sometimes be manipulated by insertion of a blade into the space between the door and frame while the lock box is liable to damage particularly as the movable part is frequently struck by the lock bolt.

It is an object of the invention to provide a deadlock to give durable and reliable service particularly but not only when operated by remote control.

According to the invention there is provided a deadlock for a closure of an aperture including at least one movable dead bolt selectively operable to engage between the aperture and the closure, a bias means to bias the dead bolt(s) away from a position providing said engagement, a body of magnetically susceptible material operatively coupled to the dead bolt(s), an operating arrangement effective when the closure is near the aperture and including a first magnet to act on said body and through the coupling to operate the dead bolt(s) against the bias to engage between the closure and the aperture and keep the closure bolted there, the arrangement including a second magnet selectively operable to act on said body to overcome the first magnet action and through the coupling disengage the dead bolt(s) allowing the closure to be moved to open the aperture.

The operating arrangement may be in two parts one on the closure the other on the aperture with one of the magnets on the closure. One magnet may be an electromagnet. The second magnet may be the electromagnet and fitted on the closure for selective operation to allow the closure to be opened. The dead bolt(s) may be installed on the closure and the aperture provided with dead bolt socket(s) to receive the bolts in bolting engagement whether the closure is near to or at the aperture. The first magnet may position the closure more closely to the aperture than the dead bolt(s) and socket(s).

The electromagnet may be arranged for selective energisation in both possible polarities, one to oppose the permanent magnet to open the closure and the other to assist the permanent magnet to close the closure. A reed switch may be provided responsive to the permanent magnet to control the energisation.

The second magnet may be selectively operable from one or more remote positions by either direct energisation of an electromagnet or operation of a permanent magnet by remote control such as a mechanical or electromechanical linkage.

Embodiments of the invention will now be described with reference to the accompanying drawing which shows part of an aperture and closure of a door frame and door with a deadlock embodying the invention.

The drawing shows a door frame DF in which Door D is fitted e.g. to swing on hinges. Other door motions are possible, e.g. sliding, folding, up and over etc., and a deadlock according to the invention is usable with these motions as well. A lock box LB is fitted either in the door thickness or on "safe" side of the door, e.g. the inside of main entrance door or a block of flats. The box LB may be of a non-magnetic metal, e.g. stainless steel, brass or aluminium, or of plastics. Stainless steel is particularly suitable when the lock box is exposed and liable to accidental or wilful damage and vandalism. The lock box LB contains part of an operating arrangement of the deadlock and one end of a dead bolt DB. Part of the lock box provides a bolt guide BG for dead bolt DB.The bolt DB extends through a hole BM in the door D to a position for co-operation with a bolt-box BB .in door frame DF. It is an important feature of the invention that a close fitting engagement of the bolt DB in box BB is not required, for reasons to be explained later. Preferably the lock box is fitted near to the door corner reducing the length of the bolt DB to the minimum amount, say a few inches only.

A bolt-operating coupling is provided in lock box LB. The coupling includes a lever link LK in the form of a bell-crank with one elongated arm ending in an operating quadrant slot OQ. A bolt drive pin BP passes through the slot OQ and bolt DB to link them securely together to trasmit motion of quadrant OQ to bolt DB. Link LK is pivotted on main pivot pin MP at the end of a short crank arm and a tension bias spring BS is attached to the short lever arm of link LK. The link LK is shaped to allow it to swing on pivot MP within the elongate lock box LB to move quadrant OQ to drive bolt DB up and down. In the illustrated embodiment bolt DB moves at least 10 mm and may move up to 15 mm or more for the full permitted swing of link LK. The swing of link LK is damped by a dashpot DP connected to the link by a fork F and a pivot pin PP.This damping reduces noise and vibration on the movement of link LK in the box LB.

The operating arrangement also includes a first and a second magnet. In the illustrated embodiment the first magnet is a permanent magnet PM and the second magnet an electromagnet EM. Electromagnet EM is placed on an armature AR of a body of magnetically susceptible material such as a solid soft iron core.

The armature body AR is connected to lever link LK as shown.

An external electric circuit XC extends from the electromagnet windings to an external d.c. power supply XP, at least one external switch XS1,XS2 . . XSn and an optional timer T. The wiring can conveniently pass through the hinge area. By suitable techniques the hinges themselves might provide circuit paths.

Locks are preferably installed at upper and lower outer door corners. An auxiliary closing element of a permanent magnet such as PM and an electromagnet EM can also be installed at the mid-height of the door. To act as an auxiliary closing element electromagnet EM is energised to attract magnet PM. To open the door the energisation is reversed and if required increased.

The period of closing energisation could be controlled by a reed switch responsive to the field of the permanent magnet PM and auxiliary electronic logic circuits if required to prevent maloperation with small reversals of door movement. These modifications can also be applied to the components in the lock box if desired. The energisation to aid closure is ended when the door is closed, e.g. by the operation of a microswitch by the door.

The arrangement of the elements described will be explained with reference to an operating cycle. Assume that door D is open and lock box LB is some distance, say 6 inches (150 mm) or more from first magnet PM. Electromagnet EM is not energised. Link LK will be acted on by spring BS to be in a position such that quadrant OQ is in position OQ', pivot PP in position PP' and the electromagnet EM and armature AR displaced as outlined by dotted line EM1. Bolt DB is pulled down in the drawing, to be withdrawn into door D by the connection through pin BP.

Door D is now moved towards the frame DF to reduce,the distance of lock box LB, and armature AR, from permanent magnet PM. Typically a conventional door closer or other means, such as rising butt hinges, is used to ensure the movement occurs when the door is left open. The movement can be aided as described above by suitable energisation of the coils in the locks themselves.

As the more intense part of the field from magnet PM is entered, when the door nears the frame, armature AR is drawn towards the full line position in the drawing, against spring BS. Bolt DB is driven upwards to project from the door D.

Suitable striker plates or guides are provided to enable the bolt to enter box BB in the door frame DF. The action of permanent magnet PM also brings the door to the closed position. It is not essential that the bolt DB is a close fit in box BB.

Provided that the box holds the bolt against escape or forcing the fit can be quite loose, say at least 1/8 inch (3 mm), as the magnet PM will cooperate with armature AR to keep the door in a closed position in the door frame, even if wind pressure attempts to move it. It is preferable that the frame does not have a jamb as this will reduce the risk of "rattle" noise. Adequate draughtproofing techniques exist for jambless door types, e.g. close-bristled brush strips.

To open the door now bolted in the door frame electromagnet EM is energised by use of one of switches XS, to XSn from supply XP via timer T.

The windings of electromagnet EM are chosen so that armature AR has an induced magnetisation to repel it from permanent magnet PM swinging lever link LK away from the full line extreme position to the other extreme position. Bolt DB is withdrawn freeing the door from the frame so that the door can be opened. Timer T, which is optional, can be arranged to maintain the energisation of the electromagnet for a set period, say 5 seconds. The nature of power source XP, switches XS, to XSn and timer T is not crucial to the invention subject to the polarisation mentioned below. Typically the switches and power supply could be those used for conventional electromagnetic locks, with any relevant changes to power rating. One or more switches can be an external key-operated switch.

Dashpot DP damps the movements of the lock, smoothing the action of the bolt.

In another embodiment the electromagnet EM may be fixed in the lock box on separate soft iron cores and the magnetic circuit completed by an armature or permanent magnet on the link LK.

The action would be similar to that described for a moving electromagnet but electrical connections would be simpler as movement need not be allowed for.

The lock box arrangement may be installed so that there is minimal or no clearance between the permanent magnet and armature to produce the best control of the door in the closed position.

While the above description is of a deadlock particularly suitable for the main, outward opening door of a bRock of flats clearly other door plans may be used. A door may be arranged to be held locked shut by an energised electromagnet and only be openable when the energisation fails, e.g. by using a fire alarm call to cut the supply.

The electrical arrangement could be reversed, with the electromagnet on the door frame. Other variations are possible within the scope of the invention set out above. The power supply can be high or low voltage a.c. or d.c. Clearly when the electromagnet action is reversible polarised energisation is needed, and can be provided either by a battery or suitably rectified a.c. A suitable permanent magnet provides at least 401b force and possibly up to 601b or more which is appropriate for a normal 2m xl m external door exposed to wind. The electromagnet for such a permanent magnet is arranged to exert a similar force. High quality permanent magnets such as those based on Alnico (R. T. M.) are desirable.

The manner of operation of the locks and the uncritical box dimension and position simplify construction of a door or other closure such as a trap door, partition and the like. One or more locks can be positioned almost anywhere on the door or frame, out of reach of users and vandals, and need not weaken the door by being cut into it. In -the preferred arrangement a lock is provided at the upper and lower outer door corners, the drawing showing the lock in an upper corner.

Such locks may be used separately, e.g. to open only one or two doors of a set. The progressive action of shooting the bolt under the influence of magnet PM can assist in the proper closing of the door. One lock can be arranged to shoot two bolts, one up, one down.

The above description discloses a magnetically operated dead bolt which by its form and mounting freedom is less likely to be damaged while providing a secure lock resistant to attempts to force it. The appearance of the door is not altered as much of the lock is invisible in use.

Panic-release arrangements such as levers linked to a crash-bar on the inside face of the door can be provided if required.

Claims (1)

1. Claims

   1. A deadlock for a closure of an aperture including at least one movable dead bolt selectively operable to engage between the aperture and the closure, a bias means to bias the dead bolt(s) away from a position providing said engagement, a body of magnetically susceptible material operatively coupled to the dead bolt(s), an operating arrangement to be effective when the closure is near the aperture and including a first magnet to act on said body and through the coupling to operate the dead bolt(s) against the bias to engage between the closure and the aperture and keep the closure bolted there, the arrangement including a second magnet selectively operable to act on said body to overcome the first magnet action and through the coupling disengage the dead bolt(s) allowing the closure to be moved to open the aperture.

   2. A deadlock according to claim 1 in which the operating arrangement is in two parts, one fittable on the closure the other fittable on the aperture and with one of the magnets in the closure part.

   3. A deadlock according to claim 1 or claim 2 in which at least one of the magnets is an electromagnet.

   4. A deadlock according to claim 3 in which the second magnet is the electromagnet and fittable on the closure for selective operation to allow the closure to be opened away from the aperture.

   5. A deadlock according to any one of claims 1 to 4 including dead bolt socket(s) adapted for aperture mounting for cooperation with dead bolt(s) adapted for closure mounting and to receive the bolt(s) in bolting engagement when the closure is near to and/or seated in the aperture.

   6. A deadlock according to claim 5 in which the first magnet is effective to hold the closure seated more tightly to the aperture than the engagement of the dead bolt(s) and socket(s).

   7. A deadlock according to any one of the preceding claims in which the coupling is a swing link mounted to swing on a pivot at or near to one end and having an operating quadrant to extend and retract the deadbolt via a bolt peg as the link swings on the pivot.

   8. A deadlock according to claim 7 in which the body of magnetically susceptible material is attached to the swing link to swing the link in response to the action of the first magnet and extend the dead bolt.

   9. A deadlock according to claim 7 in which the second magnet is an electromagnet attached to the swing link to swing the link, when the magnet is made operable by energisation, to overcome the first magnet action, and retract the deadbolt.

   10. A deadlock according to claim 8 and claim 9 in which the body of susceptible material is the core of the electromagnet.

   1 A deadlock according to claim 7 in which the bias means is a pull-off spring attached to the swing link to swing the link to retract the bolt.

   12. A deadlock substantially as herein described with reference to the accompanying drawings.

   13. A system of a door, a door frame and a deadlock to bolt the door to seat in the frame substantially as herein described with reference to the accompanying drawings.

   1 4. A deadlock control arrangement including electrical remote control substantially as herein described with reference to the accompanying drawings.

   1 5. A system of a door, a door frame and at least one deadlock according to any one of claims 1 to 12 mounted in the door for selective action to bolt the door to seat in the frame and release the door from the frame and including door closing means of an electromagnet energisable to pull the door into the frame and an electromagnet control circuit of a reed switch responsive to the approach of the door to the door frame to energise the electromagnet and a microswitch responsive to the seating of the door in the frame to deenergise the electromagnet.

   New Claims or Amendments to Claims filed on 1 9th Sept. 1980.

   Superseded Claims 1 and 1 5.

   New or Amended Claims:

   1. A deadlock for a closure of an aperture including at least one movable dead bolt selectively operable to engage between the aperture and the closure, a bias means to bias the dead bolt(s) away from a position providing said engagement, a body of magnetically susceptible material operatively coupled to the dead bolt(s), an operating arrangement for distribution between the closure and the aperture to be effective only when the closure is near the aperture and including a first magnet to act on said body and through the coupling to operate the dead bolt(s) against the bias to engage between the closure and the aperture and keep the closure bolted there, the arrangement including a second magnet selectively operable to act on said body to overcome the first magnet action and through the coupling disengage the dead bolt(s) allowing the closure to be moved to open the aperture.

   1 5. A system of a door, a door frame and at least one deadlock according to any one of claims 1 to 12 and claim 16 mounted in the door for selective action to bolt the door to seat in the frame and release the door from the frame and including door closing means of an electromagnet energisable to pull the door into the frame and an electromagnet control circuit of a reed switch responsive to the approach of the door to the door frame to energise the electromagnet and a microswitch responsive to the seating of the door in the frame to deenergise the electromagnet.

   1 6. A deadlock according to any one of Claims 1 to 12 in which the first magnet is a permanent magnet to provide a dead-locking action with the dead bolts.