LOCKS

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) is inserted in the keyway (20) and the key and rotor magnets interact to turn the rotors into posi­ tions 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 sur­ rounding body thus pressing in the plungers and permitting rotation of the barrel. Barrel (8) is a "servant" barrel and barrel (9) is a "master". In Fig. 1 barrel (8) lies within a pocket (12) in the slot (10) to block throwing of the bolt. Turning it through 90° permits the bolt to be single-thrown (to 2′) whereupon it is blocked against further extension by barrel (9) in pocket (15) and blocked against retraction by barrel (8) in pocket (14) when (8) is rotated back to its locked position. Turning barrel (9) through 90° now permits the bolt to be double-thrown (to 2′) whereupon it is blocked against retraction by barrel (9) in pocket (17) when the latter is rotated back to its locked position. Retraction of the bolt involves the reverse sequence.

Description: 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 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 permanentlymagnetised 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. 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 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 singlethrown 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 accompanying drawings, in which: Figure 1 is a side elevation, partly in section, of a lock according to the invention, with a side cover plate removed; Figure 2 is a plan view of the lock of Figure 1; Figure 3 is a longitudinal cross-section, to an enlarged scale., through a barrel for the lock of Figures 1 and 2; Figure 4 is a partial transverse cross-section through the barrel of Figure 3 and its housing; and Figure 5 illustrates the form of key for operating the barrel of Figures 3 and 4. The lock shown in Figures 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 double-throw 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 2' in Figure 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 Figure 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 cooperates 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 Figure 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 first1 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 crosssectional profiles of the barrels where they extend through the slots being indicated in Figure 1 from which it is seen that in this region each barrel presents a truncated cylindrcal 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 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 Figure 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 "master" key, 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 Figure 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, therefore, the correct "servant" key is inserted into key-guide 20 and turned to rotate the barrel 8 through 90O so that its flats 18 are now 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 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 single-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 doublethrown (2") position as the gate 16 passes over the barrel 9, the locked "servant" barrel 8 imposing no constraint 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 singlethrown position, so it will be seen tha the "master" barrel 9 controls movement of the bolt in either direction 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 respective barrel is freed for rotation as described above is based upon the provision of a series of magnetically-coded tumblers, as will now be more fully explained with reference to Figures 3 and 4 which illustrate more fully the structure 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 8 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 (Figure 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,26B and 26C,26D respectively (herein called "rotors") borne for rotation about radiallyaligned 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 nonmagnetic 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 plunger 23, thereby allowing retraction of the latter. A form of key 31 suitable for this purpose is illustrated in Figure 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 Figure 5 as A,B,C,D along flank 33 of the stem and in the reverse order on the opposite flank 34. ;hen this key is fully inserted into the guide 20 (ie up to a stop surface 35 on the key) from the side of the lock corresponding to the lower end of Figure 3 zone A on flank 34 comes into register with the magnetic rotor element 29A, zone B on flank 34 registers with element 29B, 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 29B, 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-29B respectively. Turning now to Figure 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 plungers are freed to retract into the barrel 8, turning the barrel clockwise (in the sense of figure 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 (Figure 3) contacting a fixed abutment (not shown) in the lockcase when the 90a 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 applied 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-26D 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-26D is limited by the spring force of the strips 36, in contrast to the situation which would obtain if rigid camming surfaces on the housing 2G 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 reading" technique. 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 35 as previously described. The totally enclosed (in the peripheral sense) key-guides 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 above-described lock will find application.

Claims: CLAIMS 1. A lock characterised by: a bolt (2/3) adapted to slide between locking and unlocking positions; a drive element (5) for sliding the bolt as aforesaid in response to manipulation of an associated handle; the bolt (2/3) or a member movable therewith being formed with a slot (10,11) comprising two pocket portions (12,14;15,17) lying on an axis parallel to the direction of movement of the bolt (2/3) and separated by a gate portion (13,16) having a lesser dimension in a direction transverse to said axis; a rotatable barrel (8,9) separate from said drive element intersecting the said slot (10,11) ; said barrel (8,9) having an external profile where it intersects said slot (10,11) such as to be accommodated for rotation in either of said pocket portions (12,14;15,17) but such that in a first rotational position thereof the gate portion (13,16) of the slot is unable to pass over the barrel (8,9) by movement with the bolt along said axis while in a second rotational position thereof said gate portion (13,16) is able so to pass; and said barrel (8,9) carrying a plurality of permanently-magnetised tumblers (26A-26D) the magnetic fields of which normally interact to bias said tumblers (26A-26D) into positions in which they collectively block rotation of the barrel (8,9) from its first to its second position but which tumblers (26A-26D) can be moved into positions in which they collectively permit such rotation of the barrel (8,9), by magnetic interaction with a correct, magnetised key (31) inserted into the barrel (8,9). 2. A lock according to claim 1 wherein there are a pair of said tumblers (26A,26B;26C,26D) borne in the barrel (8,9) for rotation about respective axes which lie transverse to the axis of rotation of the barrel; the barrel (8,9) further including a moveable plunger (23) normally biased to extend generally radially from the barrel (S,9) into a body (26) surrounding the barrel thereby to block rotation of the barrel; said pair of tumblers (26A,26B:26C,26D) normally blocking retraction of said plunger (23) into the barrel (8,9) but those tumblers having respective relieved portions (28) which, when the tumblers (26A-26D) are moved by a correct key (31) as aforesaid, collectively define a recess into which said plunger (23) can so retract thereby to free the barrel (8,9) for rotation; and comprising means (36) in said body (26) presenting an inclined face adjacent to said plunger (23) when in its extended position whereby torque applied to the barrel (8,9) in a specified direction causes the plunger (23) to press against that face (36) 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 (36) mounted in said body (26) and arranged such that, when the plunger (23) is blocked by said tumblers (26A-26D) against retraction into the barrel (8,9), the application of torque as aforesaid causes the plunger (23) to be urged by contact with the spring element (36) onto said pair of tumblers (26A,26B;26C,26D) and thereafter to displace the spring element (3G), thus permitting limited rotation of the barrel (8,9) to a position in which the plunger (23) engages a face (39) of said body (26) to resist such torque while limiting the force with which the plunger (23) is urged onto the tumblers (26A26D). 4. A lock according to claim 2 or claim 3 wherein there are two such pairs of tumblers (26A,26B;26C,26D) and associated plungers (2,3), located at diametrally opposite positions cn said barrel (8,9). 5. A lock according to claim 4 wherein the tumblers in each said pair (26A,26B;26C,26D) are spaced apart along the axis of the barrel (8,9) and each respective tumbler (26A,26D) faces a tu.nbler of the opposite pair across a key-guide (20) which extends axially within the barrel (8,9) 6. A lock according to claim 5 wherein said key-guide (20) extends throughout the length of the barrel (8,9) and is open at each end thereof, all of the tumblers (26A-26D) in said two pairs being spaced from one end of said key-guide (20) by a distance which is less than the spacing from the other end of the key-guide (20) of the tumblers (26B,26C) closest thereto. 7. A lock according to claim 6 in combination with a magnetised key (31) adapted for insertion into said key-guide (20) from either end thereof such as to move said tumblers (26A-26D) as aforesaid, the key (31) having four zones of magnetisation (A-D) on each of two opposite flanks (33,34) thereof arranged so that when the key (31) is inserted through said one end of the key-guide (20) to an extent defined by stop means (35) of the key the trailing two said zones (C,D;A,B) on each said flank (33,34) register with respective tumblers (26C,26D;26A,26B) in respective said pairs, and when the key (31) is inserted through said other end of the key-guide (20) to an extent defined by said stop means (35) the leading two said zones (A,B;C,D,) on each said flank (33,34) register with respective tumblers (26A,26B;26C,26D) in respective said pairs. 8. A lock according to any preceding claim wherein the external profile of said barrel (8,9) where it intersects said slot (10,11) is in the form of a truncated cylinder with two opposed flat surfaces (18,19) spaced apart by a dimension slightly less than the said dimension of said gate portion (13,16). 9. A lock according to any preceding claim wherein said bolt (2,3) is adapted to slide between an unlocking position (2) and a single-thrown locking position (2'), and between said single-thrown position (2') and a double-thrown locking position (2''), and wherein there are two such barrels (8,9) each intersecting a respective said slot (10,11) and arranged so that a first said barrel (8) must be rotated to its said second rotational position to permit movement of the bolt between its unlocking (2) and single-thrown (2') positions, and the second said barrel (9) must be rotated to its said second rotational position to permit movement of the bolt between its single-thrown (2') and double-thrown (2'') positions. 10. A lock according to claim 9 wherein the said slot (10) with which the first said barrel (8) intersects comprises a first said pocket portion (12) configured to block movement of the bolt (2/3) away from its unlocking position (2) when the first barrel (8) is accommodated therein in its said first rotational position, and a second said pocket portion (14) configured to permit movement of the bolt (2/3) between its single-thrown (2') and double-thrown (2'') positions, but to block movement of the bolt from its single-thrown (2') to its unlocking position (2), when the first barrel (8) is accommodated therein in its said first rotational position; and the said slot (11) with which the second said barrel (9) intersects comprises a first said pocket portion (15) configured to permit movement of the bolt (2/3) between its unlocking (2) and single-thrown (2') positions, but to block movement of the bolt from its single-thrown (2') to its double-thrown (2'') position, when the second barrel (9) is accommodated therein in its said first rotational position, and a second said pocket portion (17) configured to block movement of the bolt (2/3) away from its double-thrown position (2'') when the second barrel (9) is accommodated therein in its said first rotational position.

Inventors: ROBINSON, WILLIAM KEITH, ROGERS, JOHN
Applicants: CHUBB & SON'S LOCK AND SAFE COMPANY LIMITED
Application year: 1984
Main classification: E05B47
IPC codes: E05B47, E05B35