GB2429036A - Lock assembly with hookbolt and deadlocking latch - Google Patents

Abstract

A lock assembly for a door comprising a casing 1, a locking mechanism arranged at least partly within the casing and having a hook bolt 7, a latch bolt 8 and a deadlock assembly 30,33,36, which, when the hook bolt is in a locked configuration, effects locking of the latch bolt 8. A pin 29 on the hook bolt engages a surface 34 to urge the deadlocking assembly downwards as the hook bolt rotates to the locked position (fig.4) and engage ratchet teeth 35 with the latch bolt 8. A spring 32 assists the disengagement of the deadlock assembly when the hook bolt is unlocked.

Description

Lock assembly The invention relates to lock assemblies.

Certain lock assemblies include a movable hook-like latch, known as a hook bolt, which can engage with a keeper provided upon the door surround at the location in which the lock will abut the door surround when the door is closed.

The lock assembly is mortise fitted within a recess that opens at the side edge of the door, that is, the edge that, when the door is closed, abuts the adjacent surface of the door surround.

Certain kinds of doors having a hook bolt are susceptible to forcing by an intruder. In particular, if a bar or other elongate implement can be forced between the door and the door surround, vertical motion of the bar may be sufficient to force open the hook bolt, thus allowing the door to be forced open.

There is a need for improved lock assemblies which are less susceptible to forcing.

The invention provides a lock assembly for a door, comprising: a casing; a locking mechanism arranged at least partly within the casing and having a hook bolt; a latch bolt; and a deadlock assembly which is in cooperation with the latch bolt and is further so in cooperation with the hook bolt that, when the hook bolt is in a locked configuration, the deadlock assembly effects locking of the latch bolt.

The provision of a deadlock as defined above enables the latch bolt to be locked against inadvertent or deliberate unauthorised opening when the hook bolt is in the closed position.

In one preferred arrangement, the hook bolt is arranged to be above the latch bolt when the lock is fitted and the deadlock assembly is positioned between the hook bolt and the latch bolt. The positioning of the hook bolt above the latch bolt is advantageous in that the latch bolt presents an obstruction to an intruder attempting to slide an object vertically upwards against the hook bolt in order to force the hook bolt open.

It is preferred for the hook bolt to be in sliding interaction with the deadlock assembly.

The deadlock assembly advantageously comprises interlocking means that are interlockable with complemetary interlocking means associated with the latch bolt.

Advantageously, the latch bolt is movable substantially horizontally by a movable member comprising the complementary interlocking means, and the deadlock assembly is able to lock the movable member in a fixed position.

Preferably, the interlocking means and complementary interlocking means comprise interlockable ratchet means.

Advantageously, the interlockable ratchet means each comprise a plurality of asymmetric tips.

In one embodiment, the hook bolt is pivotable about a pivot and comprises an element eccentrically arranged relative to the pivot for acting upon the deadlock assembly.

It is preferred for the deadlock assembly to comprise a bearing surface with which the element interacts for effecting vertical displacement of the deadlock assembly.

Preferably, the deadlock assembly is slidably movable in a substantially vertical direction. Preferably, the deadlock assembly comprises a compression spring for urging the deadlock assembly, in use, away from the latch bolt. The compression spring may be a helical compression spring.

By way of example, one embodiment of the invention will now be described with reference to the accompanying drawings, of which: Fig. 1 is a perspective view from below of a lock assembly for a door according to one embodiment of the invention; Fig. 2 is a side view of the lock assembly of Fig. 1; Fig, 3 is a side view of an upper part of the lock assembly with its casing removed and with the hook bolt shown in the unlocked condition; Fig. 4 is a side view of the upper part of the assembly from the same side as Fig. 3 and with the hook bolt in a locked condition; and Fig. 5 is a perspective view of the hook bolt.

With reference to Figs. 1 and 2, the lock assembly is in many respects conventional. It is a mortise lock and includes a lock casing 1 into which the locking mechanism of the lock is fitted. The lock casing 1 includes a front faceplate 2 and a rear wall 3. The lock casing also includes opposed side walls 4 and opposed upper and lower walls 5,6.

The lock assembly is suitable for use in a variety of doors, for example, but not exclusively, in a sliding door.

It includes a hook bolt 7 and a retractable bevelled latch bolt 8, which are arranged in the vicinity of corresponding apertures in the faceplate 2. The hook bolt 7 is arranged to be interlockable with a keeper mounted on the door surround, for example with a cooperating member or aperture provided on the keeper. The latch bolt 8 is so arranged that it can be advanced into a corresponding aperture in the keeper. The cooperating member and keeper are not shown in the drawings. The lock assembly is designed to be mortise fitted within the section of a part of the door, typically within a frame section of the door. When received within the door, the housing of the lock assembly is concealed except for the faceplate 2, which is arranged to be substantially level with the surrounding surface of the side edge of the door, that is, the surface that in use will be the leading surface when the door is slid shut. Items of lock furniture may be added to the assembly, for example, a lock cylinder (not shown in Fig. 1) may be provided in aperture 9 and extend through the front face of the door.

The positions of the hook bolt and the latch bolt are inverted relative to conventional lock arrangements. That facilitates opening of the door and is in particular advantageous where the door is to be used by disabled persons. Furthermore, in that way the latch bolt impedes any implement inserted by an intruder with the objective of forcing the hook bolt upwards from below. The structure and operation of the lock cylinder are otherwise conventional.

Other lock furniture may be attached to the lock assembly. For example, a handle may be mounted in square aperture 10.

In Fig. 3 there is shown an upper part of the lock assembly with the casing omitted and with certain parts of the lock mechanism omitted for ease of illustration. Whilst the latch bolt shown in the drawings has a chamfered end the invention is also applicable to the case where the latch bolt has a square end.

The latch bolt 8 and its operating mechanism are located in the lower part of the assembly shown in Fig. 3.

The latch bolt is retractable and extendable through an aperture in the faceplate 2 by means of a slideable member 11 which is moveable to and fro in a horizontal direction.

The slideable member 11 is attached to the latch bolt 8 via a neck portion 12 and includes a bolt-carrying portion 13 and an elongate portion 14. The rear of elongate portion 14 is received in a horizontally extending channel (not shown) provided on the interior of the casing wall and is able to slide horizontally to and fro therein for the purpose of retracting or extending the latch bolt 8. The elongate portion 14 cooperates with a compression spring 15. At a first end 16 of the elongate portion 14, a first end 17 of the spring 15 bears upon a return portion 18 of the elongate member 14, whereby the return portion 18 is moveable with the elongate portion 14 relative to the casing. In the vicinity of the other end 19 of the elongate portion 14, a plate 20 is provided in a fixed position on the interior of the casing wall and extending into the interior of the lock assembly. The second end 21 of spring 15 bears on the plate in such a manner that, on retraction of the latch bolt 8 by means of drawing slidable member 11 including elongate member 14 from left to right in Fig. 3, the spacing between the return portion 18 and plate 20 is reduced, causing compression (or further compression) of the spring 15.

A ratchet surface 22 is provided on the top of the elongate portion 14. The ratchet surface is suitably configured to cooperate with a deadlock assembly by which the latch bolt 8 can be locked into the closed position when the hook bolt is operated, that deadlock assembly being described further below.

The hook bolt 7 is pivotable about a pivot 23 between an unlocked condition shown in Fig. 3 and a locked condition shown in Fig. 4. The mechanism for causing pivoting of the hook bolt 7 between the locked and unlocked positions by means of a lock cylinder and associated key is conventional and is therefore not described herein. The hook bolt 7 is shown in more detail in Fig. 5, from which it may be seen that it has a hook portion 24. The hook bolt has two substantially parallel members 25, 26 which are spaced apart, the space between the members 25,26 being occupied in a part of the hook bolt, including the hook portion 24, by metal inserts 27. Adjacent to the pivot 23 is a pin 29 which is fixed to each of, and extends between, the members 25, 26.

The pin 29 is provided for the purpose of interaction with the deadlock assembly.

The deadlock assembly has a deadlock body 30, cooperating with compression spring 32, the purpose of which is to cause the deadlock body portion 30 to be urged in the upward direction when the door is unlocked, as is further explained below. The spring at one end contacts a plate 30a that extends inwardly from the deadlock body 30. The other end of the spring 31 is arranged upon a plate 32, which extends forwardly from the casing of the lock assembly.

Extending upwardly from the deadlock body 30 is a curved extension member 33, which provides a bearing surface 34 for the pin 29. Extending downwardly from the bottom of the deadlock body are ratchet tips 35 of a ratchet edge 36 provided on a plate portion 37 of the deadlock body 30. A vertically extending channel (not shown) for receiving the deadlock body 30 is provided on the interior of the lock assembly casing, and the deadlock body 30 is slideable vertically to and fro within that channel.

The bearing surface 34 is so configured and the position of the pin 29 relative to the pivot 23 is so selected that, on closing of hook bolt 7, the pivoting movement of the hook bolt 7 results, through the action of the moving pin 29 upon the bearing surface 34, in the deadlock assembly, including the ratchet edge 36, being urged downwards. Thus, on moving the hook bolt from the unlocked position shown in Fig. 3 to the locked position shown in Fig. 4, the ratchet edge 36 is caused to move downwardly to interact with the complementary ratchet surface 22 on the elongate member 14, thereby locking the latch bolt 8 against horizontal movement. As a result, the spring 31 is compressed.

When the hook bolt is unlocked, the pin 29 moves in a clockwise direction and on reaching an upper return portion of the bearing surface 34 serves to lift the extension member 33 and the attached deadlock body 30 including the ratchet edge 36. The compressed spring 31 also urges the deadlock upwardly and, in the event of breakage of the extension member 33, thus ensures that the latch bolt will not remain in the locked position. Thus, on failure of the extension portion 30, opening of the door is not prevented by the deadlock assembly so that a user will in those circumstances still be able to open the door.

The lock assembly can be fitted in essentially the same manner as conventional mortise locks.

It will be apparent that the invention is applicable to any mortise lock, and in particular to mortise locks which are suitable for any kind of door, including hinged doors or sliding doors.

Claims (11)

1. Claims 1. A lock assembly for a door, comprising: a casing; a locking

   mechanism arranged at least partly within the casing and having a hook bolt; a latch bolt; and a deadlock assembly which is so in cooperation with the hook bolt that, when the hook bolt is in a locked configuration, the deadlock assembly effects locking of the latch bolt.
2. 2. A lock assembly according to claim 1, in which the hook bolt is to be arranged above the latch bolt when the lock is fitted, and the deadlock assembly is positioned between the hook bolt and the latch bolt.
3. 3. A lock assembly according to claim 1 or claim 2, in which the deadlock assembly comprises interlocking means that are interlockable with complementary interlocking means associated with the latch bolt.
4. 4. A lock assembly according to claim 2, in which the latch bolt is movable substantially horizontally by a movable member comprising the complementary interlocking means, and the deadlock assembly is able to lock the movable member in a fixed position.
5. 5. A lock assembly according to claim 3 or claim 4, in which the interlocking means and complementary interlocking means comprise interlockable ratchet means.
6. 6. A lock assembly according to claim 5, in which the interlockable ratchet means each comprise a plurality of asymmetric tips.
7. 7. A lock assembly according to any one of the preceding claims, in which the hook bolt is pivotable about a pivot and comprises an element eccentrically arranged relative to the pivot for acting upon the deadlock assembly.
8. 8. A lock assembly according to claim 7, in which the deadlock assembly comprises a bearing surface with which the element interacts for effecting vertical displacement of the deadlock assembly.
9. 9. A lock assembly according to any one of the preceding claims, in which the deadlock assembly is slideably movable in a substantially vertical direction.
10. 10. A lock assembly according to claim any one of the preceding claims, in which the deadlock assembly comprises a compression spring for urging the deadlock assembly, in use, away from the latch bolt.
11. 11. A lock assembly substantially as described herein with reference to and as illustrated by the accompanying drawings.