GB2575170A

GB2575170A - Improvements to mortise locks

Info

Publication number: GB2575170A
Application number: GB201906980A
Authority: GB
Inventors: Chantler Roger; Southall Ian
Original assignee: UAP Ltd
Current assignee: UAP Ltd
Priority date: 2018-05-22
Filing date: 2019-05-17
Publication date: 2020-01-01
Anticipated expiration: 2039-05-17
Also published as: GB2600218A; GB202111867D0; GB201906980D0; GB2575170B; GB2600218B; GB201808355D0

Abstract

A mortise lock with a deadbolt 27 and a gate 50 and pawl 41 arrangement operated by a cam lever 47 of a cylinder lock 48. The pawl is a sliding member engaged by cam lever and is selectively engaged by the gate via intermeshing teeth. At least one tooth has orthogonal bottom and side surfaces engaging with complementary shaped groove, preferably rectangular, e.g. square teeth and grooves. The gate is preferably spring biased and prevents sliding of the pawl. The gate may include a second tooth of triangular shape locating in grooves with inclined surfaces (52, 58, fig.7). the pawl may include tapered surfaces (65, 66, fig.7) to hinder manipulation by a tool. The pawl may be guided by protrusion (45, fig.7) in a slot in the casing, such guide slots in the case can be covered by forming them as a partial blind groove/slot.

Description

IMPROVEMENTS TO MORTISE LOCKS

The present invention relates to mortise locks for doors and other similar closures.

A mortise lock is located within a mortise that is cut into the door, window or other closure. Typically, such a mortise lock comprises a lock case that houses a latch, which may be a non-locking sprung latch or a hooked latch that is operated by a door handle and is termed a sash lock. Alternatively or in addition, the lock case may include a dead bolt that is operated by a pin-tumbler lock cylinder such as a euro-style lock cylinder. Such a lock cylinder operates a rotatable cam with a projecting cam lever that bears against a portion of the mortise lock to move the dead bolt between locked and unlocked positions wherein it either protrudes from the lock case or is retracted back into the lock case respectively.

For example and as shown in Figs, la and ib, a mortise lock i may comprise a pawl and gate arrangement wherein a movable pawl 2 is slidable between locked and unlocked positions and interacts with a spring-loaded gate 3 that in turn moves a hooked latch 4 and a dead bolt (not shown) between extended and retracted positions. The pawl 2 is adapted on one side by the provision of a cut-away portion 5 whereby it is engaged by a projecting cam lever 6 of a euro-style lock cylinder 7 and on the other side engages the spring-loaded gate 3. The pawl 2 and the gate 3 engage one another by means of intermeshing teeth. In particular, the pawl 2 comprises a pivotally mounted rack 8 formed by a single tooth 9 on either side of which is a groove

10. The gate 3 comprises a U-shaped member 11 defining a single, projecting tooth 12 and is spring-loaded as at 13 so that the tooth 12 engages the rack 8. In addition, the gate 3 comprises a projecting lug 14 with a profiled edge 15 that projects through a central transverse aperture in the pawl 2. A similar rack 8 and tooth 12 may be provided on the pawl 2 and the gate 3 respectively on the opposite side of the lug 14.

When the cam lever 6 is moved to change the mortise lock i from a locked (Fig. la) to an unlocked (Fig. ib) state, both the pawl 2 and the gate 3 are moved by the cam lever 6, which is rotated as the cylinder lock 7 is opened. The pawl 2 defines a projecting finger 16 that in its locked position prevents movement of an extension 17 to a rack of a rack and pinion or other gear mechanism (not shown) controlling operation of the dead bolt. Sliding movement of the pawl 2 by the cam lever 6 moves the finger 16 away from the rack extension 17 to permit its movement up and down the lock 1. Movement of the rack extension 17 also controls movement of the hooked latch 4. The gate 3 is also moved translationally at right angles to the movement of the pawl 2 against the loading of the spring 13 by action of the rotating cam lever 6 on the profiled edge 15 of the lug 14. The sliding movement of the rack 8 forces the tooth 12 on the gate 3 out of one of the grooves 10 over the tooth 9 and into the other groove 10 against the force of the spring-loading 13. The translational movement of the gate 3 causes it to acts on a lever arrangement (not shown) which moves the rack extension 17 sufficiently to open the dead bolt by movement of the gear mechanism. At the same time movement of the rack extension 17 pivots the hooked latch 4 so that it is retracted allowing the door to which the mortise lock 1 is fitted to be opened. However, once the pawl 2 is in its unlocked condition, the further rotation of the cam lever 6 away from the pawl 2 allows the gate 3 to move under the influence of its spring-loading 13 back to its initial position, thereby reengaging the hooked latch 4. This latch 4 can then be simply retracted to open the door by rotation of a handle (not shown) which turns a spindle connected to the lever arrangement that moves the rack extension 17. It will be appreciated that translational movement of the pawl 2 in the opposite direction by the cam lever 6 will similarly act on the gate 3 to move the rack extension 17 to cause projection of the dead bolt into its locked condition and also move the pawl 2 back into a position wherein the finger 16 prevents movement of the rack extension 17 to retract the dead bolt.

In order to facilitate the sliding movement of the pawl 2, the teeth 9 and 12 and the grooves 10 have triangular profiles with tapering side walls

18. However, this profile assists those who wish to attack the mortise lock i to force it into an unlocked state. As shown in Fig. 2, the exterior of a lock case 19 housing the pawl and gate arrangement described above is usually provided with cut-out portions and in particular a cut-out area 20 adjacent the location of the pawl 2 in which a projecting slider 21 on the pawl 2 locates to retain the pawl 2 in position as it slides backwards and forwards in the case 19. The cut-out area 20 allows access to the slider 21 if the side of a door or window housing the mortise lock 1 is bored into or otherwise broken into to expose this part of the lock case 19. This enables a slender tool, such as a screwdriver, to be inserted into the lock case 19 to engage and push the slider 21 and thereby the pawl 2 from its locked to its unlocked position thereby enabling the rack extension 17 to be moved to retract the dead bolt and allowing the door or window to be opened.

An object of the present invention is to provide an improved mortise lock that obstructs movement of the gate if an attempt is made to break into the lock.

According to the present invention there is provided a mortise lock comprising a lock case housing a dead bolt movable between extended and retracted positions by a gate and pawl arrangement that is adapted to be operated by a cam lever of a lock cylinder, wherein the pawl comprises a sliding member that on one side is adapted to be engaged by the projecting cam lever and that on the other engages the gate, which is biased into contact with the pawl, the pawl being slidingly movable by the cam lever between locked and unlocked positions that respectively correspond to the extended and retracted positions of the dead bolt;

the pawl and the gate engage one another by means of intermeshing teeth of uniform height; and at least one tooth of the intermeshing teeth comprises orthogonal end and side surfaces and engages in a complementarily shaped groove when the pawl is in its locked position.

The use of at least one tooth having orthogonal end and side surfaces that engages in a complementarily shaped groove when the pawl is in its locked position prevents sliding movement of the pawl by a force applied along the length of the pawl transversely across the lock case, as is normally the case when an attempt is made to move it by a tool as described above. This thwarts such an attempt to cause retraction of the dead bolt.

Preferably, the gate is spring-loaded and moved away from the pawl against the bias of its spring loading by the cam lever at the same time as the cam lever acts to move the pawl to enable the intermeshing teeth of the gate and the pawl to ride over one another.

Preferably also, the lock case comprises a side wall that forms a flap adjacent the location of the pawl, which flap obstructs the insertion of a tool into the lock case.

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. la is a side view of part of the interior of a conventional lock case showing a conventional pawl and gate arrangement with the pawl in a locked position;

Fig. ib is a view similar to Fig. la but showing the pawl in an unlocked position;

Fig, 2 is a side view of the exterior of the lock case shown in Figs, la and ib;

Fig, 3 is a side view of the interior of a lock case of a mortise lock accordingly to the present invention;

Fig. 4 is a perspective, exploded view of a pawl and gate arrangement forming part of the mortise lock shown in Fig. 3;

Figs 5a and 5b are side views of the pawl and gate arrangement shown in Fig, 4 when respectively in locked and unlocked positions;

Fig. 6 is a view similar to Fig. 5a but showing a modified pawl and gate arrangement;

Fig, 7 is a perspective view of the pawl and gate arrangement shown in Fig. 6; and

Fig. 8 is a side view of the exterior of the lock case shown in Fig. 3.

The mortise lock 25 shown in Fig. 3 is a double spindle dead bolt lock with a hooked latch. However, persons skilled in the art will appreciate that the present invention can be employed in single spindle dead bolt locks and in those with a non-locking sprung latch in place of a hooked latch. The use of a two spindles is an additional safety measure that means access can only be gained from the exterior of a door fitted with the lock by use of a key even if the door is unlocked. This feature is sometimes referred to as a “night latch function”.

Referring to Fig. 3, the lock 25 comprises a case 26 housing a dead bolt 27 that is operated by a rack and pinion arrangement 28 whereby it is either extended out of the case 26 in a locked position or retracted into the case in an unlocked position. One of the racks of the arrangement 28 comprises an extension 29 that connects the arrangement 28 to levers 30 and 31 that are respectively connected to spindles 32 and 33 via pins 34. The spindles 32 and 33 are adapted to be secured to handles (not shown) that are located on the interior and the exterior side of a door (not shown) to which the lock 25 is fitted. Typically, the spindle 32 will connect to an interior handle and the spindle 33 will connect to an exterior handle although it is possible to dispense with use of the spindle 32 and connect interior and exterior handles to the same spindle 33. The rack extension 29 is also connected via a pin 35 to a hooked latch 36 that is pivotal mounted to the casing 25 via a pivot pin 37. The hooked latch 36 is pivotable about the pivot pin 37 between an extended position, as shown in Fig. 3, and a retracted position wherein it has been rotated to lie within the lock case 26. The pins 35 and 37 travel along respective slots 38 and 39 in the rack extension 29 and the hooked latch 35 as the rack extension 29 moves up and down. The pin 35 may also travels along slot 40 in the rack extension 29 and along a groove 41 defined in the interior surface of the lock case 26. It will be appreciated that when the rack extension 29 is moved into a position wherein the dead bolt 27 is retracted, which is upwards with respect to the case 26 as shown in Fig. 3, the impact of the pin 35 against the end of the slot 39 in the latch 35 will cause the latch 35 to rotate so that it is retracted into the case 26 to allow the door to be opened.

More particularly, movement of the rack extension 29 to move the dead bolt 27 between locked and unlocked positions is controlled by a pawl and gate arrangement that will now be described.

A pawl 42 is slidingly mounted within the case 26 between locked and unlocked positions wherein it either locks the rack extension 29 so that the dead bolt 27 is locked into its extended position or frees the rack extension 29 for movement to allow retraction of the dead bolt 27. In its locked position, the pawl 42 prevents movement of the rack extension 29 by a projecting finger 43 that engages in an open slot 44 in the rack extension 29. Sliding movement of the pawl 42 into its unlocked position withdraws the finger 43 from the slot 44 allowing the rack extension 29 to be moved. The length of travel of the pawl 42 is controlled by a slider 45 that projects from the pawl 42 and locates in a slot 46 cut into the lock case 26. Sliding movement of the pawl 42 is effected by a cam lever 47 of an adjacent cylinder lock 48 that locates within an appropriate cut-out in the lock case 26. In a similar fashion to the prior art arrangement described above, one side of the pawl 42 defines a groove or cut-away portion 49 the end surfaces of which are engaged by the cam lever 47 to move the pawl 42 between its locked and unlocked positions.

A spring-loaded gate 50 interacts with the pawl 42. Again as described above, the gate 50 comprises a U-shaped member 51 that defines a single, projecting tooth 52. The gate 50 is spring-loaded as at 53 so that the tooth 52 engages a rack 54 defined by the pawl 42 on the opposite side to the groove 49. In addition, the gate 50 comprises a projecting lug 55 with a profiled edge 56 that projects through a central transverse aperture 57 through the pawl 42. A similar rack 54 and tooth 52 may be provided on the pawl 42 and the gate 50 respectively on the opposite side of the lug 55. The rack 54 comprises a central tooth 58 on either side of which is a groove 59. The teeth 52 and 58 have a uniform height but unlike the prior art arrangement shown in Figs, la and ib they have orthogonal end and side surfaces as do the grooves 59. In particular the teeth 52 and 59 have a rectangular profile, preferably a square-shaped profile, as do the complementarily shaped grooves 59. Preferably, however, these teeth 52 and 58 do have rounded rather than sharp corners. The shape of the teeth 52 and 58 and the grooves 59 prevent movement of the pawl 42 relative to the gate 50 if a force is applied only in the longitudinal direction of the slider 45, as would be the case if it is desired to tamper with it when in situ to move the pawl 42 to an unlocked position. However, when the lock 25 is in use, the cam lever 47 in addition to applying a force to the pawl 42 applies a force to the profiled edge 56 of the lug 55 and thereby raises the gate 50. This is sufficient to allow the tooth 52 to rider over the rack 54 as the pawl 42 is simultaneously moved. As with the prior art described above, movement of the pawl 42 into an unlocked position withdraws the finger 43 from the slot 46 to free the rack extension 29 for movement and at the same time causes the gate 50 to act on the lever 32 to move the rack extension 29 to retract the dead bolt 27 and pivot the hooked latch 35 allowing the door in which the lock 25 is fitted to be opened. In a similar fashion to the prior art, once the pawl 42 is in its unlocked condition, the further rotation of the cam lever 47 away from the pawl 42 allows the gate 50 to move under the influence of its spring-loading 53 back to its initial position thereby reengaging the hooked latch 35. The latch 35 can then be sufficiently retracted to open the door by rotation of either of the spindles 32, 33, which move the rack extension 29 via the pins

34. It will be appreciated that translational movement of the pawl 42 in the opposite direction into its locked position by the cam lever 47 will similarly act on the gate 50 to move the rack extension 29 to cause projection of the dead bolt 37 into its locked condition and also move the pawl 42 back into a position wherein the finger 43 prevents movement of the rack extension 29 to retract the dead bolt 27.

In a modification of the pawl and gate arrangement, as shown in Figs, 6 and 7, the pawl 42 and the gate 50 each respectively comprise an additional tooth 60 and 61 at one end and the pawl 42 defines an additional groove 62. The teeth 60, 61 are again of uniform height and these teeth and the groove 62 have orthogonal end and side surfaces and preferably have a rectangular profile, in particular a square-shaped profile with rounded corners. In addition one 59a of the grooves on the other side of the tooth 60 to the groove 62 also has orthogonal end and side surfaces. However, the teeth 52 and 58, which are of uniform height with the teeth 60, 61 have a triangular profile, as in the prior art arrangement shown in Figs, la and ib, as does the other groove 59b on the opposite side of the tooth 58 to the groove 59a. It will be appreciated that when the pawl 42 is in its locked position, the tooth 61 engages in the groove 62 and this inhibits movement of the pawl 41 if a force is applied only in the direction of the slider 45, indicated by arrow A in Fig, 6, without simultaneous movement of the gate 50 by the cam lever 47. However, when acted on by the cam lever 47 the gate 50 is raised as described above to allow the teeth 52 and 61 to ride over the rack 54.

Further measures to prevent or hamper tampering with the lock 25 may also be adopted. First, the lock case 26 may be adapted to prevent the insertion of a tool therein adjacent the pawl 42. Conventionally, the side wall of the lock case 26 is pierced by the slot 46 in which the slider 45 of the pawl 42 locates. However, as shown in Fig. 8, the slot 46 can remain covered and therefore protected against insertion of a tool therethrough if the side wall 63 of the case 26 forms a flap 64 adjacent the location of the pawl 42. This flap 64 covers the slot 46 and is may be formed by half-shearing and only partially punching the side wall 63 of the lock case 26 part-way through. Second, the slider 45 and the finger 43 of the pawl 42 may be provided with one or more chamfered or tapered edge surfaces 65 and 66 respectively, as shown in Fig. 7 but also applicable to any embodiment of the invention. These edges 65, 66 hinder the use of a tool, such as a screwdriver, to push the pawl 42 into an unlocked position by making it more difficult to gain purchase.

Claims

1. A mortise lock comprising a lock case housing a dead bolt movable between extended and retracted positions by a gate and pawl arrangement that is adapted to be operated by a cam lever of a lock cylinder, wherein the pawl comprises a sliding member that on one side is adapted to be engaged by the projecting cam lever and that on the other engages the gate, which is biased into contact with the pawl, the pawl being slidingly movable by the cam lever between locked and unlocked positions that respectively correspond to the extended and retracted positions of the dead bolt;

2. A mortise lock as claimed in Claim i, wherein the gate is springloaded and moved away from the pawl against the bias of its spring loading by the cam lever at the same time as the cam lever acts to move the pawl to enable the intermeshing teeth of the gate and the pawl to ride over one another.

3. A mortise lock as claimed in Claim 1 or Claim 2, wherein the gate comprises said at least one tooth with a rectangular profile that engages in a complementarily shaped groove defined by the pawl when the pawl is in its locked position.

4. A mortise lock as claimed in Claim 3, wherein the gate comprises a second tooth with a triangular profile that engages in a rack defined by the pawl comprising at least one tooth with a triangular profile and at least one groove having a triangular profile, the complementarily shaped groove for the rectangular profiled tooth of the gate being provided at the end of the rack.

5. A mortise lock as claimed in Claim 4, wherein the rack comprises a second tooth with a rectangular-shaped profile that separates said complementarily shaped groove from the rest of the rack.

6. A mortise lock as claimed in any of Claims 1 to 3, wherein the pawl defines a rack comprising at least one tooth and adjacent grooves that all have rectangular-shaped profiles and the gate comprises a tooth that has a rectangular-shaped profile that is complementary to the grooves in the rack.

7. A mortise lock as claimed in any of Claims 1 to 6, wherein the teeth with orthogonal end and side surfaces and their complementarilyshaped grooves have square profiles.

8. A mortise lock as claimed in any of Claims 1 to 7, wherein the teeth with orthogonal end and side surfaces and their complementarilyshaped grooves have rounded corners.

9. A mortise lock as claimed in any of Claims 1 to 8, wherein the lock case comprises a side wall that forms a flap adjacent the location of the pawl, which flap obstructs the insertion of a tool into the lock case.

10. A mortise lock as claimed in Claim 9, wherein the flap is formed by half-shearing and partially punching the side wall of the lock case part-way through.

11. A mortise lock as claimed in any of Claims 1 to 10, wherein the pawl is provided with one or more chamfered or tapered surfaces that hinder use of a tool to push the pawl into its unlocked position by making it more difficult to gain purchase.