GB2549154A

GB2549154A - Improvements to cylinder locks with thumb-turns

Info

Publication number: GB2549154A
Application number: GB1609624.0A
Authority: GB
Inventors: Jennings David; Mcloughlin John
Original assignee: UAP Ltd
Current assignee: UAP Ltd
Priority date: 2016-04-06
Filing date: 2016-06-02
Publication date: 2017-10-11
Anticipated expiration: 2036-06-02
Also published as: GB2549154B; GB201609624D0

Abstract

A cylinder lock with a thumb-turn connected to a blade 8 having at least one pin engaging groove (20, fig.8) for cooperating with a key pin 16 of at least one pin stack 14. The thumb-turn is axially movable and biased into a first position wherein the pin stack prevents rotation of a core 5 within casing 2 of cylinder lock. The thumb-turn can be moved against the bias, e.g. spring, into a second position wherein the key profile of the blade aligns the pin stacks and permits rotation of the core and cam of the cylinder lock. Preferably a captive pin locates in slot 27 to retain the thumb-turn and limit axial movement. The key blade may include grooves on opposite flat sides and the cylinder may include two sets of opposing tumblers, the narrow edge of the key-blade may also include grooves cooperating with the driver pin of the pin stack. The key-blade may be of square cross section with pin grooves on each face with four sets of pin-stacks circumferentially arranged around the core.

Description

IMPROVEMENTS TO CYLINDER LOCKS WITH THUMB-TURNS

The present invention relates to cylinder locks with a thumb-turn.

Cylinder locks are usually used in conjunction with a lock case comprising a latching mechanism for locking doors, windows and other closures. The cylinder lock typically comprises a locking mechanism that operates a rotatable cam that, when rotated, bears against a spring-loaded portion of the latching mechanism within the lock case to open it. Such locks may comprise single cylinder locks that allow locking of a closure from one side only but usually the cylinder lock is a double cylinder that extends through the closure and is adapted so that it can be operated from both sides, at least one of the sides being key-operated with the other side being either key-operated or having a thumb-turn. The cam is therefore positioned approximately mid-way along the cylinder of the lock and is selectively connected to locking mechanisms on both sides that are either operated by keys or, in the case of thumb-turns, by turning a knob or lever. The connection between the locking mechanism and the cam is effected by a clutch that is axially slidable along the cylinder between two positions wherein it is engaged by one of the lock mechanisms and turns the cam as the key or thumb-turn is rotated but is not engaged by the other of the lock mechanisms so that it can rotate freely relative thereto. In cylinder locks wherein both sides are key-operated, a key inserted fully into one side of the lock acts on the clutch to move it into the position wherein it engages the locking mechanism into which the key has been inserted. However, in cylinder locks with a thumb-turn, the clutch is usually biased into the position wherein it is normally engaged with the thumb-turn so that a user can open the closure by simply rotating the thumb-turn but can be slid into the other of the two positions by a key inserted into the other side of the lock. A problem with known locks of the type that have a thumb-turn as described above is that they are susceptible to be readily opened by an intruder if the intruder can gain access to the thumb-turn. Usually, the intruder does this via a letter-plate, which provides a convenient opening through the closure that is often located close to the lock. If the intruder can gain access to the thumb-turn via the letter-plate and pass a band or cord around the thumb-turn, it is often possible to rotate the thumb-turn by manipulation of the cord or band to open the lock without causing any damage to the lock or the closure. Such a method of opening the lock is quick and silent.

The object of the present invention is to provide a cylinder lock with a thumb-turn that will thwart such attempts to open the lock by simple rotation of the thumb-turn.

According to the present invention there is provided a cylinder lock comprising a casing; a core rotatably disposed relative to the casing and adapted to connect to a cam mechanism in order to rotate the cam mechanism as it rotates to operate a latching mechanism located adjacent the lock; a thumb-turn connected to a blade, which is located in a keyway defined by the core and which is movable longitudinally along the keyway within the core from a first position to a second position against the force of a biasing means; at least one bore defined by the core that communicates with the keyway and with a corresponding bore formed in the casing to define a pin chamber; and a spring-loaded pin stack located in the pin chamber and comprising at least two pins with an interface therebetween, which pins are located within the bores defined by the casing and the core, one end of one of the pins being engageable with the surface of a groove defined by the blade, which surface is profiled such that as the blade moves between its first and second positions said one pin is also moved within the pin chamber such that when the blade is in its first position a pin of the pin stack straddles a shear line between the core and the casing preventing rotation of the blade and thereby the core by the thumb-turn and when the blade is in its second position the interface is coincident with the shear line to permit rotation of the blade and thereby the core by the thumb-turn to rotate the cam mechanism.

Preferably, the groove is profiled such that it is chamfered at its end adjacent the thumb-turn such that as said one end of said one pin moves over the chamfer when the blade is moved into its second position the key pin is depressed into against its spring loading to bring the interface into coincidence with the shear line.

Other preferred but non-essential features of the present invention are described in the dependent claims appended hereto.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:-

Fig. l is a perspective view of a part of a cylinder lock in accordance with the invention showing a thumb-turn at one end thereof in a first position;

Fig. 2 is a side view of the lock shown in Fig. 1;

Fig. 3 is a longitudinal sectional view along the line III-III in Fig. 2;

Fig. 4 is a longitudinal sectional view along the line IV-IV in Fig. 2, which is normal to the line II-II;

Figs. 5 and 6 are similar to Figs. 3 and 4 respectively but showing the lock when the thumb-turn is in a second position;

Fig. 7 is a perspective view of a blade forming part of the lock;

Fig. 8 is a longitudinal sectional view of the blade shown in Fig, 7;

Fig. 9 is a detail to an enlarged scale of the encircled part of the blade labelled IX in Fig. 8;

Fig. 10 is a perspective view of a first modified core and blade arrangement for use in a lock in accordance with the present invention;

Figs. 11a and 11b are perspective views of the blade shown in Fig. 10 showing opposite sides thereof;

Figs. 12a and 12b are perspective views of the core shown in Fig. 10 showing opposite sides thereof;

Fig. 13 is a perspective view of a second modified core and blade arrangement for use in a lock in accordance with the present invention;

Figs. 14a and 14b are perspective views of the blade shown in Fig. 13 showing opposite sides thereof; and

Figs. 15a and 15b are perspective views of the core shown in Fig. 13 showing opposite sides thereof.

An embodiment of cylinder lock 1 in accordance with the present invention comprises a casing 2 that is adapted to extend through a closure such as a door. Usually, the casing 2 will have an exterior portion (not shown) and an interior portion connected by a central joining portion (not shown). A cam mechanism (not shown) is provided that is located adjacent the central joining portion so that it can be actuated by one or other of locking mechanisms contained within the exterior and interior portions. The cam mechanism is itself adapted to operate a latching mechanism for the closure which is usually located adjacent the casing 2 of the lock 1 within the lock case of the closure. The locking mechanism within the exterior portion of the lock 1 is usually a key-operated locking mechanism whereas the locking mechanism within the interior portion may be a thumb-turn arrangement in accordance with the present invention as is described below. However, as details of the cam mechanism, the locking mechanism in the exterior portion of the casing 2 and the latching mechanism may be conventional and are not relevant to the present invention they are not shown in the drawings and are not further described. Hence, the drawings show only the interior portion and a locking mechanism that it contains, which will now be described.

The locking mechanism comprises a core 5, which is rotatably disposed relative to the casing 2 and which has an interior end 6 that projects from the casing 2 adjacent the central joining portion. The end 6 is appropriately adapted to connect to the cam mechanism in order to rotate the cam mechanism as it rotates relative to the casing 2 in order that the cam mechanism can in turn operate the latching mechanism located adjacent the lock. It is also expected that in many cases the end 6 will be acted on by the latching mechanism via the cam mechanism to return it back to an initial position after unfastening of a latch. The particular way that the end 6 is adapted to connect to the cam mechanism is again not relevant to the present invention and is not further described.

The core 5 defines a central keyway 7 in which is inserted a blade 8. An exterior end of the blade projects from the core 5 and the casing 2 and is secured to a thumb-turn 9. The blade 8 is moveable longitudinally along the keyway 7 within the core 5 from a first position to a second position against the force of a biasing means and therefore acts in a similar way to the blade of a key. The biasing means comprises a pair of springs 10 that are located in blind bores 11 formed in the core at the interior end of the keyway 7 and that project from the bores 11 to bear against the interior edge of the blade 8. In an alternative arrangement a single centrally located spring may be used in place of the pair of springs 10. Also, the spring or springs need not be contained in bores. The springs 10 bias the blade 8 into a first position as shown in Figs. 1 to 5, wherein the blade 8 and therefore the thumb-turn 9 are urged outwardly of the core 5 and the casing 2. When the thumb-turn 9 is depressed, the blade 8 moves longitudinally along the keyway 7, compressing the springs 10 into its second position, as shown in Figs. 6 and 7.

The locking mechanism is arranged so that when the blade 8 is in its first position, the core 5 cannot be rotated relative to the casing 2 by turning the thumb-turn 9, which is turn would turn the blade 8, the thumb-turn 9 and the blade 8 being also locked against rotation. This locking mechanism will be described.

The core 5 defines at least one and preferably a plurality of radially extending bores 12 that communicates with the keyway 7 and with corresponding bores 13 formed in the casing 2. Each pair of bores 12 and 13 defines a pin chamber in which is located a spring-loaded pin stack 14. While the invention is operable with a single pair of bores 12 and 13 and a single pin stack 14, preferably there are a plurality that form a set to make the locking mechanism more secure. In the present embodiment there is a set of three pairs of bores 12 and 13 with associated pin stacks 14. It is expected that this will be an optimum number, more increasing the cost of manufacturing but fewer reducing the security of the locking mechanism.

Each of the pin stacks 14 comprises at least a driver pin 15 that is predominantly located in its respective bore 13, a key pin 16 that is located within its respective bore 12, and a spring-loading 17 that acts between the driver pin 15 and a plug 18 that is used to close off the bore 13 in the casing 2. The pin stack 14 may, however, comprise additional pins although this is not necessary for successful operation of the invention. The driver pin 15 and the key pin 16 define an interface 19 therebetween. The head of the key pin 16 opposite the interface 19 projects from the bore 12 and engages a surface of a groove 20 formed in one face of the blade 8. Each key pin 16 engages the surface of its own respective groove 20 so that there are as many grooves 20 formed in the blade 8 as there are pin stacks 14. Also, the head of the key pins 16 is profiled into a frusto-conical shape as shown in Fig., 6. In addition, as shown in Figs. 7 to 9, the surface of each groove 20 is also profiled so that as the blade 8 is moved between its first and second positions, the head of the key pin 16 moves along its respective groove 20 and is also moved perpendicularly to alter the position of the pin stack 14 within the bores 12 and 13. In particular, the surface of the groove 20 is profiled so that when the blade 8 is in its first position the driver pins 15 straddles a shear line 21 between the core 5 and the casing 2, as shown in Fig. 4. This prevents the blade 8 from being rotated by the thumb-turn 9, which is itself thereby locked against rotation. As the blade 8 cannot rotate, the core 5 is also locked against rotation and the cam mechanism remains in a locking position. However, when the blade 8 is moved into its second position by pushing the thumb-turn 9 towards the casing 2, the end of key pin 16 moves along the groove and is simultaneously depressed so that the interface 19 between the key pin 16 and the driver pin 15 coincides with the shear line 21. This permits the blade 8 to be rotated by rotation of the thumb-turn 9, the blade 8 rotating the core 5 relative to the casing 2 in order to rotate the cam mechanism.

Each of the grooves 20 is preferably profiled so that it is chamfered at its end 22 adjacent the thumb-turn 9. As the end of the key pin 16 moves over the chamfer the position of the key pin 16 in its bore 12 is simultaneously altered, being either depressed against the spring loading 17 to bring the interface 19 into coincidence with the shear line 21 or being released to allowing the driver pin 15 to return to a position wherein it straddles the shear line 21 under the influence of the spring loading 17. To this end the chamfered end 22 of the groove 20 defines a facet 23 which is angled relative to the planar face 24 of the blade 8 adjacent the groove 20. The facet 23 thereby translates longitudinal movement of the key pin 16 over it into movement of the key pin 16 in a transverse direction. The facet 23 may define an angle of between 200 and 700 relative to the planar face 24 of the blade adjacent the groove 20 but advantageously it defines an angle of 450.

At such an angle there is a 1:1 ratio of movement of the key pin 16 along the groove and along the bore 12.

In order to prevent the blade 8 from being pulled out of the keyway 7 and to control the length of travel of the blade 8 between its first and second positions, a captive pin 25 is provided within the core 5. This pin 25 is located in an additional bore 26 defined in the core 5 such that one end of the pin 25 projects into the keyway 7 and locates in a slot 27 defined by the blade 8. The length of the slot 27 thereby controls the distance that the blade 8 can travel when moving between its first and second positions in addition to preventing the blade 8 from being pulled out of the core 5.

In use, the biasing means 10 biases the blade 8 and thereby the thumb-turn 9 into its first position wherein both are locked against rotation by the driver pins 15 so that the locking mechanism remains closed. This is the normal position of the lock 1 so that if an intruder attempts to turn the thumb-turn 10 remotely from the exterior of a closure such as a door to which the lock 1 is fitted by passing a cord or band around the thumb-turn 10, the latter will not rotate. However, when it is desired to open the lock 1 from the interior of the closure, a user can do this by pushing the thumb-turn 10 towards the casing 2 against the force of the biasing means 10 thereby moving the blade 8 into its second position wherein the interfaces 19 between the key pins 16 and the driver pins 15 of the pin stacks 14 coincide with the shear line 21 to permit rotation of the blade 8 and thereby the core 5 by the thumb-turn to rotate the cam mechanism.

As indicated above, it is expected that in many cases after rotation of the cam mechanism, the end 6 of the core 5 will be rotated back to its initial or “home” position by the cam and latching mechanisms. Then, as soon as pressure on the thumb-turn 10 is released it is moved by the biasing means 10 back into its first position so that it can no longer be rotated. However, the modified embodiments of the invention that will now be described overcome the problem which arises if the closure is unlocked from the inside using the thumb-turn 9 and the latter is not returned to its initial or “home” position, either inadvertently or because there is no spring mechanism included in the cam and latching mechanism to do this. In this circumstance the core 5 is free to rotate and thus prone to illicit manipulation, for example via a letter-plate aperture from the exterior of a door or even through the front of the lock 1 if its external part has been snapped off. A lock with a first modified arrangement of core and blade will now be described with reference to Figs. 10, 11a, 11b and 12a, 12b. In this arrangement a face 28 of the blade 8 opposite the face 24 along with its two side edge faces 29 are also provided with sets of grooves 20 that are identical to the set of grooves 20 formed in the face 24, the blade 8 being made sufficiently thick to accommodate the grooves 20 in its edge faces 29. In addition, the core 2 adjacent the grooves 20 formed in the face 28 is also provided with a set of bores 30 that are identical to the set of bores 12 described above but diametrically opposed to them. These bores 30 also each contain a key pin 16 in an identical fashion to the bores 12 so that when the core 5 is turned through 18 o° from the “home” position the bores 30 can align with the bores 13 in the casing 2 and the key pins 16 in the bores 30 will form pin stacks with the driver pins 15 in the bores 13. Hence, in this position when the thumb-turn 9 and the blade 8 are in the first position the core 2 and thereby the blade 8 are both are locked against rotation by the driver pins 15 so that the locking mechanism remains closed. However, when the blade 8 is moved into its second position by pushing the thumb-turn 10 towards the casing 2 against the force of the biasing means 10 the interfaces 19 between the key pins 16 in the bores 30 and the driver pins 15 are coincident with the shear line 21 to permit rotation of the blade 8 and thereby the core 5.

In a similar fashion, the heads of the driver pins 15 are designed to enter the grooves 20 in the edge faces 29 of the blade 8 when it is turned to face them, that is at 900 to the locking positions of the core 2. As in the modified arrangement the driver pins 15 act in the same way as the key pins i6 their heads are profiled in a similar way to the head profiles of the key pins 16 as shown in Fig, 6. Hence, as the blade 8 moves between its first and second positions the driver pins 15 are also moved within the bores 13 such that when the blade 8 is in its first position the driver pins 15 straddle the shear line preventing rotation of the blade 8 and thereby the core 5 by the thumb-turn and when the blade 8 is in its second position the tips of the heads of the driver pins 15 are coincident with the shear line 21 to permit rotation of the blade 8 and thereby the core 5.

It will be appreciated that the core 2 and the blade 8 are each rotationally symmetrical at 1800 although only one captive pin 25 and slot 27 are required so that this arrangement is not repeated on the face 28 of the blade 8 and only one bore 26 is required in the core 5. This overcomes the problem described above. Should the lock 1 be operated using the thumb-turn 9 and the thumb-turn 9 not returned to its “home” position, the core 5 is no longer free to rotate but is restrained at every quarter turn by the four sets of grooves 20 formed in the blade 8. Only by pushing the thumb-turn 10 towards the casing 2 against the force of the biasing means 10 thereby moving the blade 8 into its second position as described previously can the key pins 16 or the driver pins 15 be disengaged from the grooves 20 in the blade 8 to permit rotation of the blade 8 and thereby the core 5. Otherwise, the core 5 can only be rotated a maximum of 900 in either direction. Hence, illicit tampering with the lock 1 is hampered. In a simpler arrangement, the grooves in the edge faces 29 of the blade 8 could be dispensed with but this would make the lock 1 less secure as it would only be restrained at every half turn. A second modified arrangement of core and blade is shown in Figs. 13, 14a, 14b and 15a, 15b and the lock comprising these operates on a similar principal to that with the first modified arrangement. Here the blade 8 is modified so that it has an angular cross-sectional profile, in particular a substantially square profile, and locates in a complementarily shaped keyway 31 in the core 5 so that it no longer has edges that coincide with the shear line 21. However, each face of the blade 8 is provided with a set of grooves 20 that are identical to the set of grooves 20 formed in the face 24 of the original embodiment as described above. Again, only one of these faces comprises a slot 27 for the captive pin 25. The core 5 is also provided with additional sets of bores 30 that are identical to the set of bores 12 described above so that they are all arranged circumferentially at 900 intervals around the core 5. These bores 30 also each contain a key pin 16 in an identical fashion to the bores 12. Hence, when the core 5 is turned so that the bores 30 align with the bores 13 in the casing 2 the key pins 16 of each set will form pin stacks with the driver pins 15 in the bores 13.

This second modified embodiment operates in a similar manner to the first. Should the lock 1 be operated using the thumb-turn 9 and the thumb-turn 9 not returned to its “home” position, the core 5 is again no longer free to rotate but is restrained at every quarter turn by the driver pins 15 straddling the shear line 21. Only by pushing the thumb-turn 9 towards the casing 2 against the force of the biasing means 10 thereby moving the blade 8 into its second position as described previously and the key pins 16 along the grooves 20 in the blade 8 are the driver pins 15 moved so that their heads are coincident with the shear line 21. This then permits rotation of the blade 8 and thereby the core 5. Otherwise, the core 5 can only be rotated a maximum of 900 in either direction.

Although in the description of the first and second modified embodiments above, “sets” of grooves and bores have been referred to it should be appreciated that each “set” may comprise a single groove 20 or a single bore 12. However, preferably each set comprises three grooves 20 or bores 12 for the reasons set out in the description of the main embodiment. Also, in principle in both the first and second modified embodiments more than four locking positions around the circumference of the core could be catered for by altering the cross-sectional profile of the blade 8 appropriately. However, in practice the number of locking positions is limited by the amount of space within the core 5 for additional sets of bores and key pins. Also, the cost of such a lock would be unnecessarily increased.

Claims

1. A cylinder lock comprising a casing; a core rotatably disposed relative to the casing and adapted to connect to a cam mechanism in order to rotate the cam mechanism as it rotates to operate a latching mechanism located adjacent the lock; a thumb-turn connected to a blade, which is located in a keyway defined by the core and which is movable longitudinally along the keyway within the core from a first position to a second position against the force of a biasing means; at least one bore defined by the core that communicates with the keyway and with a corresponding bore formed in the casing to define a pin chamber; and a spring-loaded pin stack located in the pin chamber and comprising at least two pins with an interface therebetween, which pins are located within the bores defined by the casing and the core, one end of one of the pins being engageable with the surface of a groove defined by the blade, which surface is profiled such that as the blade moves between its first and second positions said one pin is also moved within the pin chamber such that when the blade is in its first position a pin of the pin stack straddles a shear line between the core and the casing preventing rotation of the blade and thereby the core by the thumb-turn and when the blade is in its second position the interface is coincident with the shear line to permit rotation of the blade and thereby the core by the thumb-turn to rotate the cam mechanism.

2. A lock as claimed in Claim l, wherein the groove is profiled such that it is chamfered at its end adjacent the thumb-turn such that as said one end of said one pin moves over the chamfer when the blade is moved into its second position the key pin is depressed into against its spring loading to bring the interface into coincidence with the shear line. 3· A lock as claimed in Claim 2, wherein movement of the blade under the influence of the biasing means from its second position back into its first position moves said one end of said one pin back along the chamfered end of the groove causing a pin of the pin stack to straddle the shear line.

4. A lock as claimed in Claim 2 or Claim 3, wherein the chamfered end of the groove defines a facet that defines an angle between 20°and 700 relative to a planar face of the blade adjacent the groove.

5. A lock as claimed in any of Claims 2 to 4, wherein the facet defines an angle of 450 relative to the planar face of the blade adjacent the groove.

6. A lock as claimed in any of Claims 1 to 5, wherein grooves are formed in opposing faces of the blade and corresponding bores are formed diametrically opposite to one another in the core.

7. A lock as claimed in any of Claims 1 to 6, wherein the pin stack comprises a driver pin and a key pin, which are respectively located within the bores defined by the casing and the core.

8. A lock as claimed in Claim 7, wherein grooves are also formed in opposing edge faces of the blade into, which grooves a head of the driver pin will enter when the blade is turned so that said grooves align with the bore in the casing containing the driver pin.

9. A lock as claimed in Claim 8, wherein the head of the driver pin is profiled such that as the blade moves between its first and second positions the driver pin is also moved within its bore in the casing such that when the blade is in its first position the driver pin straddles the shear line preventing rotation of the blade and thereby the core by the thumb-turn and when the blade is in its second position the tip of the head of the driver pin coincides with the shear line to permit rotation of the blade and thereby the core.

10. A lock as claimed in any of Claims 1 to 6, wherein the blade has an angular cross-sectional profile and locates in a complementarity shaped keyway in the core, each face of the blade being provided with a groove, a spring-loaded driver pin is located within the bore defined by the casing, and the core has a plurality of bores arranged at intervals circumferentially around the core in each of which bores is a key pin that is engageable with one of the grooves in one of the faces of the blade such that when the core is turned in the casing each bore can sequentially align with the bore in the casing so that the key pin it contains forms said pin stack with the driver pin in bore in the casing.

11. A lock as claimed in Claim 10, wherein the blade has a square cross-sectional profile.

12. A lock as claimed in any of Claims l to n, wherein a captive pin is located in an additional bore defined in the core, an end of the captive pin locating in a slot defined by the blade such that as the blade moves between its first and second positions the end of the captive pin moves from one end of the slot to the other end, the length of the slot thereby limiting the length of travel of the blade between its first and second positions.

13. A lock as claimed in any of Claims 1 to 12, wherein the core and the casing define a plurality of corresponding side-by-side parallel bores that form a set and in which bores are pins such that as the core is turned in the casing the bores in the or each set of the core sequentially align with the set of bores in the casing so that the pins they contains form a set of pin stacks.

14. A lock as claimed in Claim 13, wherein the core and casing there are at least three side-by-side parallel bores in each set and at least three corresponding profiled slots defined by the blade.

15. A cylinder lock substantially as described herein with reference to Figs. 1 to 9, Figs. 1, 2 and 10 to 12b, or Figs. 1, 2 and 13 to 15b of the accompanying drawings.