GB2151295A - Locks using magnetic keys - Google Patents

Abstract

The lock has a bolt 2,3 which is shifted by handles on either side of the door, attached to a spindle 4. Movements of the bolt are controlled by two rotatable barrels 8 and 9 intersecting the profiled slots 10 and 11 in the bolt tail. In each barrel a pair of plungers 23 are sprung out into recesses in the surrounding lock body to block rotation of the barrel. Inward movement of the plungers to free the barrel is normally blocked by pairs of magnetic rotors 26A/26B, 26C/26D. To unblock the plungers a correctly coded magnetic key (Fig. 5 not shown) is inserted in the keyway 20 and the key and rotor magnets interact to turn the rotors into positions in which respective arcuate cut-outs 28 in the rotors align with the plungers 23. Turning the barrel now causes the plungers 23 to ride on inclined surfaces in the surrounding body thus pressing in the plungers and permitting rotation of the barrel. <IMAGE>

Description

1 GB 2 151 295A 1

SPECIFICATION

Locks The present invention relates to locks and seeks in particular to provide a high-security key-operated door lock of robust construction.

In accordance with the invention a lock comprises: a bolt adapted to slide between locking and unlocking positions; a drive element for sliding the bolt as aforesaid in response to manipulation of an associated handle; the bolt or a member movable therewith being formed with a slot comprising two pocket portions lying on an axis parallel to the 80 direction of movement of the bolt and separated by a gate portion having a lesser dimension in a direction transverse to said axis; a rotatable barrel separate from said drive ele- ment intersecting the said slot; and barrel having an external profile where it intersects said slot such as to be accommodated for rotation in either of said pocket portions but such that in a first rotational position thereof the gate portion of the slot is unable to pass over the barrel by movement with the bolt along said axis while in a second rotational position thereof said gate portion is able so to pass; and said barrel carrying a plurality of permanently-magnetised tumblers the magnetic fields of which normally interact to bias said tumblers into positions in which they colictively block rotation of the barrel from its first to its second position, but which tumblers can be moved into positions in which they collectively permit such rotation of the barrel, by magnetic interaction with a correct, magnetised key inserted into the barrel.

In a preferred embodiment, the bolt is adapted to slide between an unlocking position and a single-thrown locking position, and between said single-thrown position and a double- thrown locking position, and there are two such barrels each intersecting a respective said slot and arranged so that a first said 110 barrel must be rotated to its said second rotational position to permit movement of the bolt between its unlocking and single-thrown positions, and the second said barrel must be rotated to its second rotational position to permit movement of the bolt between its single-thrown and double-thrown positions.

These and other features of the present invention will be more particularly described, by way of example, with reference to the 120 accompanying drawings, in which:

Figure 1 is a side elevation, partly in sec tion, of a lock according to the invention, with a side cover plate removed; Figure 2 is a plan view of the lock of Fig. 1; 125 Figure 3 is a longitudinal cross-section, to an enlarged scale, through a barrel for the lock of Figs. 1 and 2; Figure 4 is a partial transverse cross-section through the barrel of Fig. 3 and its housing; 130 and Figure 5 illustrates the form of key for operating the barrel of Figs. 3 and 4.

The lock shown in Figs. 1 and 2 has a reciprocable dead bolt borne in a case 1 and comprising a head 2 fast with a plate-like tail 3. This bolt can be thrown and withdrawn by turning handles (not shown) which are connected to a spindle 4 on either side of the lock; the spindle 4 turns a follower 5 keyed to it inside the lockcase and which drives the bolt 2/3 through a pin-and-slot connection 6/7. The illustrated embodiment is a doublethrow lock. That is to say the bolt is arranged to be extended from its illustrated, withdrawn, position to a single-thrown position in which its head 2 protrudes from the lockcase by a certain distance (indicated at 21 in Fig. 1), and can then be further extended to a double- thrown position in which the head 2 protrudes from the lockcase by a greater distance (as indicated at 2" in Fig. 1). To control these movements of the bolt two magnetic locking barrels 8 and 9 are provided, each being rotatable about an axis transverse to the direction of movement of the bolt by operation of a respective correct key. It is arranged that a first of these keys-which for convenience we shall call the -servant- key and which coop- erates with the upper barrel 8-controls throwing and retracting movement of the bolt between its retracted and single-thrown positions, while the other key-which for convenience we shall call the -master- key and which cooperates with the lower barrel 9-controls throwing and retracting movement of the bolt between its single and double-thrown positions, but neither key can perform the function assigned to the other. The mechanism by which this control is exercised will now be described.

As seen in Fig. 1, the bolt tail 3 has two profiled slots 10 and 11, each comprising three distinct portions arranged along a respective axis parallel to the direction of movement of the bolt. That is to say the slot 10 comprises a first, generally circular pocket 12 adjacent to the bolt head 2, followed by a gate 13 of lesser width which opens out into a second, elongate pocket 14. The profile of the slot 11 is similar, except that the order of its three portions is reversed as compared with slot 10, so that from its leading to its trailing end it comprises an elongate pocket 15, a gate 16 and a generally circular pocket 17. The barrels 8 and 9 each intersect a respective slot 10, 11, the cross- sectional profiles of the barrels where they extend through the slots being indicated in Fig. 1 from which it is seen that in this region each barrel presents a truncated cylindrical exterior surface with two opposed flats 18 and 19 respectively; the dimension between the respective pairs of flats 18 and 19 is just slightly less than the width of the gate 13,16 in the 2 GB 2151 295A 2 corresponding bolt slot 10 or 11. Each barrel 8,9 is normally locked against rotation relative to the lockcase with its flats 18,19 oriented as shown in Fig. 1, ie perpendicular to the direction of movement of the bolt. Each barrel can, however, be released for rotation by the insertion of a correct -servant- or---masterkey, as the case may be, into the respective barrel's key-guide 20 or 21. The magnetic key-recognition mechanism by which the barrels are selectively locked or freed for rotation will be described hereinafter.

From Fig. 1 it is seen that in the retracted condition of the bolt, the servant- barrel 8 lies in pocket 12 of slot 10 while the---master- barrel 9 lies in pocket 15 of slot 11. In this condition the barrel 8 blocks throwing movement of the bolt since the gate 13 cannot pass over the arcuate surfaces of that barrel, but the barrel 9 lying in the elongate pocket 15 imposes no such constraint on bolt movement. In order to throw the bolt, there fore, the correct -servant- key is inserted into key-guide 20 and turned to rotate the barrel 8 through 90' so that its flats 18 are now 90 aligned with the gate 13. By turning the external handle the bolt can now be moved to its single-thrown (2') position as the gate 13 passes over the barrel 8, movement of the bolt being checked by the gate 16 of slot 11 coming up against the locked -master- barrel 9 (the position of which relative to the bolt now being that which is indicated at 9).

Returning the -servant- barrel 8 through 90' to its locked condition places it in the position 100 relative to the bolt which is indicated at 8', in which retraction of the bolt is now blocked. In this way it will be seen that the -servant barrel 8 controls movement of the bolt in either direction between its retracted and sin- 105 gle-thrown conditions independently of the master- barrel 9.

In order now to double-throw the bolt, if desired, the correct---master-key is inserted into the key-guide 21 and turned to rotate the barrel 9 through 90' so that its flats 19 are aligned with the gate 16. By further turning of the external handle the bolt can now be moved to its double-thrown (2") position as the gate 16 passes over the barrel 9, the locked -servant- barrel 8 imposing no con straint on this movement until the double thrown position is reached (8") as it lies within the elongate pocket 14. Returning the ---master-barrel 9 through 90' to its locked condition (9") now blocks the bolt against retraction towards its single-thrown position, so it will be seen that the---master-barrel 9 controls movement of the bolt in either direc tion between its single and double-thrown conditions independently of the "servant" barrel 8.

The key-recognition mechanism of each locking barrel 8 and 9 by which the respec tive barrel is freed for rotation as described 130 above is based upon the provision of a series of magnetically-coded tumblers, as will now be more fully explained with reference to Figs. 3 and 4 which illustrate more fully the struc- ture of the---servant"barrel 8. The structure of the---master-barrel 9 is identical-the difference between the barrels being only in the coding of the magnetic tumblers described below-so the drawings and description will not be duplicated in this respect.

The barrel 18 is provided with a pair of opposed radial bores 22 within which a pair of plungers 23 are slidably borne and biased to protrude beyond the periphery of the barrel by light springs 24. In their extended condition the plungers 23 lie in respective recesses 25 (Fig. 4) in a fixed housing 26 surrounding that part of the barrel, to lock the barrel against rotation. Associated with each plunger is a pair of rotary tumblers 26A,2613 and 26C,26D respectively (herein called---rotors---) borne for rotation about radially-aligned pins 27. Each rotor is of generally cylindrical form having an arcuate segmental cut-out 28. The cut-outs 28 in the rotor pairs 26A,26B and 26C,26D are profiled such that in a specified relative rotational position of the rotors in each pair the associated plunger 23 is able to be displaced radially inwards to release the barrel 8 for rotation in the housing 26, the plunger extending into the aligned cut-outs 28 in this movement, but in all other relative rotational positions of the rotors they block the plungers 23 against such retraction. Mounted to each rotor 26A-26D is a respective ferrite element 29A-29D upon which permanent magnetic poles have been induced in a specified relationship to the respective rotor cut-outs 28.

The principle of operation of the magnetic rotors 26A-26D is as follows. That is to say the interaction of the magnetic forces between the rotors in each pair normally acts to bias each rotor to a position in which it blocks the retraction of the corresponding plunger 23 into the barrel 8. If, however, a correctly coded magnetic key is slid into the key-guide 20, (the flanks of which are defined by plates 30 of a non-magnetic grade of stainless steel or other non-magnetic material) the resultant magnetic forces established between each rotor and the adjacent key portions serve to rotate each rotor to the position in which its cut-out 28 aligns with the corresponding plun- ger 23, thereby allowing retraction of the latter. A form of key 31 suitable for this purpose is illustrated in Fig. 5. Along each flank 33/34 of the key stem 32 which is received in the key-guide 20 in use of the key there are four zones of permanent magnetisation, labelled in Fig. 5 as A, 13,Q1) along flank 33 of the stem and in the reverse order on the opposite flank 34. When this key is fully inserted into the guide 20 (ie up to a stop surface 35 on the key) from the side of the 3 GB 2 151 295A 3 lock corresponding to the lower end of Fig. 3 zone A on flank 34 comes into register with the magnetic rotor element 29A, zone B on flank 34 registers with element 2913, zone C on flank 33 registers with element 29C and zone D on flank 33 registers with element 29D. Similarly, when the key 31 is inserted into the guide 20 from the opposite side of the lock zone A on flank 33 comes into register with the magnetic rotor element 29A, zone B on flank 33 registers with element 2913, zone C on flank 34 registers with element 29C and zone D on flank 34 registers with element 29D. On each zone A,B,C, D on each flank of the key stem permanent magnetic poles have been induced in such orientations as to cause the rotors 26A-26D to move to their unblocking positions by the magnetic forces established between those zones and the rotor elements 29A-2913 respectively.

Turning now to Fig. 4 this shows the interrelationship between the barrel plungers 23 and the surrounding housing 26. In each recess 25 there is mounted a strip 36 of spring metal presenting an inclined face to the corresponding plunger 23. Assuming that the correct key has been inserted in the key-guide 20 so that the plunger are freed to retract into the barrel 8, turning the barrel clockwise (in the sense of Fig. 4) causes the domed outer ends of the plungers 23 to run along the strips 36 and cam the plungers into the barrel, overcoming the bias of springs 24, thus permitting unblocking of the lock bolt 2/3, rotation of the barrel being stopped by a radial pin 37 (Fig. 3) contacting a fixed abutment (not shown) in the lockcase when the 90' position has been reached. If, however, an incorrect key or some other form of tool is inserted into the guide 20 and an attempt is made to turn the barrel 8 the plungers 23 will be blocked from retracting by the misaligned tumblers 26A-26D. Anticlockwise torque ap- plied to the barrel will be resisted by the rotors 23 in contact with the side walls 38 of the recesses 25. If a clockwise torque is applied, the plungers will be pressed by their contact with spring strips 36 onto the rotors 26A-26A and thereafter, since the plungers are blocked from further retraction, the strips 36 will be deflected outwards by the plungers as the barrel is permitted to rotate through the small angle required to engage the plungers 23 with the opposite side walls 39 of the recesses 25. Further rotation of the barrel is then blocked. By this means, however hard the barrel 8 may be forced, the force with which the plungers 23 can be pressed in upon the relatively delicate rotors 26A-261) is 125 limited by the spring force of the strips 36, in contrast to the situation which would obtain if rigid camming surfaces on the housing 26 were to be employed to press in the rotors 23.

A lock constructed as described above is capable of providing a high degree of security against unauthorised operation or "picking", through use of the magnetised rotors 26.

Furthermore, the key(s) 31, being coded magnetically as opposed to mechanically coded with cuts or other formations characteristic of conventional keys, are impossible to duplicate by any -sight readingtechnique. At the same time, the lock is well adapted to resist forceful attacks or other forms of abuse. For example, the interlocking of the barrels 8,9 within the slots 10, 11 provides strong resistance to forcing of the bolt, either by pressure applied directly to the bolt head 2 or through the associated handle(s). Forced turning of the barrels 8,9 is also resisted without risk of damage to the rotors 26 by provision of the spring strips 36 as previously described. The totally enclosed (in the peripheral sense) keyguides 20, 21 provide no access to the rotors 26 for manipulation or forcing of the same. Being in the form simple channels extending all the way through the barrels 8,9, however, the key-guides 20,21 cannot easily be blocked up, or if extraneous objects should be inserted into them they will be easy to clear, attempts to frustrate the authorised key-operation of locks by the insertion of articles into their keyholes being a particular problem in certain kinds of institution in which the abovedescribed lock will find application.

Claims (12)

1. A lock comprising: a bolt adapted to slide between locking and unlocking positions; a drive element for sliding the bolt as afore said in response to manipulation of an associ ated handle; the bolt or a member movable therewith being formed with a slot comprising two pocket portions lying on an axis parallel to the direction of movement of the bolt and separated by a gate portion having a lesser dimension in a direction transverse to said axis; a rotatable barrel separate from said drive element intersecting the said slot; said barrel having an external profile where it intersects said slot such as to be accommodated for rotation in either of said pocket portions but such that in a first rotational position thereof the gate portion of the slot is unable to pass over the barrel by movement with the bolt along said axis while in a second rotational position thereof said gate portion is able so to pass; and said barrel carrying a plurality of permanently- magnetised tumblers the magnetic fields of which normally interact to bias said tumblers into positions in which they collectively block rotation of the barrel from its first to its second position but which tumblers can be moved into positions in which they collectively permit such rotation of the barrel, by magnetic interaction with a correct, magnetised key inserted into the barrel.

2. A lock according to claim 1 wherein a 4 GB 2 151 295A 4 there are a pair of said tumblers borne in the barrel for rotation about respective axes which lie transverse to the axis of rotation of the barrel; the barrel further including a moveable plunger normally biased to extend generally radially from the barrel into a body surrounding the barrel thereby to block rotation of the barrel; said pair of tumblers normally blocking retraction of said plunger into the barrel but those tumblers having respective relieved portions which, when the tumblers are moved by a correct key as aforesaid, collectively define a recess into which said plunger can so retract thereby to free the barrel for rotation; and comprising means in said body presenting an inclined face adjacent to said plunger when in its extended position whereby torque applied to the barrel in a specified direction causes the plunger to press against that face thus to urge the plunger towards its retracted position.

3. A lock according to claim 2 wherein said inclined face is presented by a spring element mounted in said body and arranged such that, when the plunger is blocked by said tumblers against retraction into the barrel, the application of torque as aforesaid causes the plunger to be urged by contact with the spring element onto said pair of tumblers and thereafter to displace the spring element, thus permitting limited rotation of the barrel to a position in which the plunger engages a face of said body to resist such torque while limiting the force with which the plunger is urged onto the tumblers.

4. A lock according to claim 2 or claim 3 wherein there are two such pairs of tumblers and associated plungers, located at diametrally opposite positions on said barrel.

5. A lock according to claim 4 wherein the tumblers in each said pair are spaced apart along the axis of the barrel and each respective tumbler faces a tumbler of the opposite pair across a key-guide which extends axially within the barrel.

6. A lock according to claim 5 wherein said key-guide extends throughout the length of the barrel and is open at each end thereof, all of the tumblers in said two pairs being spaced from one end of said key-guide by a distance which is less than the spacing from the other end of the keyguide of the tumblers closest thereto.

7. A lock according to claim 6 in combination with a magnetised key adapted for insertion into said key-guide from either end thereof such as to move said tumblers as aforesaid, the key having four zones of magnetisation on each of two opposite flanks thereof arranged so that when the key is inserted through said one end of the keyguide to an extent defined by stop means of the key the trailing two said zones on each said flank register with respective tumblers in respective said pairs, and when the key is inserted through said other end of the keyguide to an extent defined by said stop means the leading two said zones on each said flank register with respective tumblers in respective said pairs.

8. A lock according to any preceding claim wherein the external profile of said barrel where it intersects said slot is in the form of a truncated cylinder with two opposed flat surfaces spaced apart by a dimension slightly less than the said dimension of said gate portion.

9. A lock according to any preceding claim wherein said bolt is adapted to slide between an unlocking position and a singlethrown locking position, and between said single-thrown position and a double-thrown locking position, and wherein there are two such barrels each intersecting a respective said slot and arranged so that a first said barrel must be rotated to its said second rotational position to permit movement of the bolt between its unlocking and single-thrown positions, and the second said barrel must be rotated to its said second rotational position to permit movement of the bolt between its single-thrown and double-thrown positions.

10. A lock according to claim 9 wherein the said slot with which the first said barrel intersects comprises a first said pocket portion configured to block movement of the bolt away from its unlocking position when the first barrel is accommodated therein in its said first rotational position, and a second said pocket portion configured to permit movement of the bolt between its single-thrown and double-thrown positions, but to block movement of the bolt from its single-thrown to its unlocking position, when the first barrel is accommodated therein in its said first rotational position; and the said slot with which the second said barrel intersects comprises a first said pocket portion configured to permit movement of the bolt between its unlocking and single-thrown positions, but to block movement of the bolt from its single-thrown to its double-thrown position, when the second barrel is accommodated therein in its said first rotational position, and a second said pocket portion configured to block movement of the bolt away from its double-thrown position when the second barrel is accommodated therein in its said first rotational position.

11. A lock substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.

12. A lock according to claim 11 in combination with a key substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935. 1985, 4235. Published at The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.