GB2496992A - Lock assembly having pivotal lock bolt with tapered cross section - Google Patents

Abstract

A lock assembly comprising a pivotal hook bolt mounted for pivotal movement in a lock casing between a retracted position and an extended position wherein it protrudes from the lock casing; the hook bolt having a tapered cross section such that at the point at which it extends from the casing its width as measured parallel to the pivot axis is at its greatest at the mid-point and narrower at the ends such that the cross section of the hook bolt may be oval shaped.

Description

Lock and handle assemblies The present invention relates to a lock assembly and more particularly, but not exclusively, to a multipoint lock assembly. The invention also relates to a handle assembly suitable for use in such a lock assembly and to a door assembly including such a lock or handle assembly.

Nultipoint lock assemblies are commonly used tc lock doors, especially UPVC doors, at both and lower regions of the door and in a mid-height region of the door. All the locks are operated by one or more mechanisms provided on the door and operated by a handle and/or a key. Designing such lock assemblies so that they can be manufactured inexpensively is especially challenging because of the need for the assemblies tc be strong and the complexity of the mechanisms required to cause the various locking and latching members to be actuated by the handle and/or key.

A particular challenge when designing a multipoint lock assembly (typically for a door) is to provide sufficient strength to tolerate side loading on an extended locking member. In order to withstand such side loading, the outwardly projecting portion of the locking member must itself be sufficiently strong and it must be capable of transmitting side loads back into the casing which in turn must be able accommodate thcse loads.

An object of the invention is to provide a lock assembly, in particular but not exclusively a multipoint lock assembly, which can be made inexpensively and can be provided with a good ability to withstand side loads. A further object of the invention is to provide improvements in a handle assembly, in particular but not exclusively for a look assembly.

According to a first aspect of the invention there is provided a multipoint lock assembly including a casing and a latch member mounted for movement between extended and retracted positions, the casing including a single part that provides a front face including an opening to allow movement of a latch member between extended and retracted positions, a first side extending rearwardly from a first side edge of the front face and at least partly providing a mounting for the latch member, and a second side opposite the first side and extending rearwardly from a second side edge of the front face, the second side edge being opposite the first side edge.

By providing a casing in which at least portions of opposite sides of the casing are provided by the same part, it becomes possible to produce a casing of improved strength and also of a reduced number of parts, which makes the design simpler and cheaper.

rhil5t it is within the scope of the invention for the second side to extend rearwardly to the same extent as the first side, that may complicate assembly of the various parts of the lock assembly and it is preferred that the second side extends rearwardly tess far than the first side. For example, the second side may generally extend more than one fifth but less than one half of the distance rearwardly that the first side extends. Also, the second side may not extend along the whole length of the second side edge of the front face but preferably does extend along more than half the length of the second side edge, thereby significantly strengthening the casing. In an embodiment of the invention described below, the second side is present along most of the length of the second side edge but not at each end thereof.

The casing preferably includes a further part TO connected to the second side of the single part and extending rearwardly from the second side of the second part. The further part can then be secured to the single part after certain other parts have been fitted into the casing. Preferably, the further part extends rearwardly about as far as the first side of the single part. Usually it is desirable that the casing is of generally cuboidal shape. Thus the first and second sides of the casing are preferably substantially parallel. Similarly, the front face of the casing is preferably substantially perpendicular to the first side.

The single part and the further part preferably indllde adjacent side edges and tabs projecting from the side edges and arranged to overlie or underlie the adjacent part for restraining relative movement of the parts in a direction perpendicular to the second side of the single part. The single part and the further part are preferably disposed in substantially parallel planes and, more preferably, are substantially coplanar. Preferably both the single part and the further part are provided with tabs and the further part includes at least one portion overlying and at least one portion underlying the single part, whereby relative movement of the parts in either of the two opposite directions perpendicular to the second side of the single part are restrained.

The casing preferably includes one or more fasteners fastening the further part to the single part. The one or more fasteners may be rivets.

TO The single part preferably further provides a rear side of the casing, the rear side extending substantially perpendicularly from a rear edge of the first side of the casing. This again reduces the number of parts and enables the casing to be strengthened.

The latch member is preferably a hook bolt. Whilst the invention of the first aspect is applicable to a wide range of lock assemblies and it is within the scope of the invention for the latch member to take a wide variety of forms, the invention is especially advantageously applied to Lock assemblies employing hook bolts.

It should be understood that the terms "latch" and "latching member" are used herein in a broad sense and include for example a member (chamfered or not) that may be used to perform a latching function without any locking facility (including for example a simple door handle mechanism) and a locking bolt (chamfered or not) that may be linearly or pivotally mounted, or mounted for a more complex movement.

In order to enhance the security of the lock assembly, an anti-drill plate is preferably provided over a portion of a side of the casing. The anti-drill plate may overly part of the latching member. A pair of anti-drill plates may be provided on opposite sides of the casing. The anti-drill plate or plates are preferably made of a material harder than the material from which the single part is made.

The lock assembly may include a further latch member.

In an errbodiment described below the assembly includes a hook bolt and a chamfered latch member. The lock assembly may also include one or more linearly movable actuating bars for actuating further locking or latching members. A rack and pinion drive is preferably provided for driving a linearly movable actuating bar.

At least one deadlocking mechanism is preferably provided.

In the case where the assembly includes a hook bolt the actuation of the hook bolt is preferably arranged such that, when the hook bolt is extended, external pressure on the bolt to move it back into a retracted position is resisted. In an embodiment of the invention described below that is achieved by providing a curved slot for a cam follower fixed to the hook bolt; the cam follower bears against a side wall of the slot to resist the external pressure referred to above. The slot may be provided in a locking bar.

The lock assembly may include a handle, preferably a pair of handles pivotally mounted on opposite sides of the casing for movement about a common axis. The handles may be connected to respective rotary drive members. The respective rotary drive members are preferably each capable of driving a common drive member which is preferably pivotally mounted. The common drive member may also be capable of being driven by another driver which is operated by an actuating means other than the handles. The other actuating means may be a key-operated mechanism, for example a tumbler pin cylinder assembly, or an electrically operated assembly.

According to a second aspect of the invention there is provided a lock assembly including: a lock casing; a hook bolt pivotally mounted in the lock casing for pivoting movement between an extended position in which a portion of the hook boiLt projects through an opening in a front face of the casing and a retracted position in which the projecting portion of the bolt is contained at least substantially within the casing; wherein, when the hook bolt is in an extended position, the cross-section of the portion of the hook bolt passing through the opening in the front face of the casing is of a generally elongate shape having an overall width measured between opposite sides of the cross-section in a first direction parallel to the axis of pivoting of the hook bolt that is less than an overall length measured between opposite ends of the cross-section in a second direction perpendicular to the first direction, wherein the overall width of the cross-section is greatest in a middle portion of the cross-section spaced from each of its ends and the overall width reduces towards each of the ends of the cross section, and wherein the sides of the cross-section are adjacent to the boundary of the opening in the front face of the casing.

A conventional hook bolt would have a rectangular TO cross-section where it passes through an opening on the front face of its casing. By providing a hook bolt where the cross-section is greatest in the middle portion and decreases towards each of its ends, it becomes easier to avoid any concentration of forces at the interface of the hook bolt and the casing when side loads are transferred from the hook bolt into the casing. Thus it becomes possible for the lock assembly reliably to withstand larger side loads on the hook bolt.

Preferably the sides of the cross-section are adjacent to the boundary of the opening in the front face of the casing along substantially the whole length of each side.

Such an arrangement enables side loads applied to the hook bolt to be transmitted to the casing along the entire length of a side of the cross-section.

Preferably, the ends of the cross-section are adjacent to the boundary of the opening in the front face of the casing. This enables the opening in the casing to be of the smailest possible size enabting the casing to be stronger.

The overall width of the cross-section is preferably greatest midway along the sides of the cross-section. For example the width may be more than 10 per cent greater midway along the sides than in the regions of the ends of the cross-section. The sides of the cross-section are preferably smoothly curved. It is desirable to avoid any discontinuity in the sides to avoid stress concentrations.

In an especially preferred form of the invention each of the opposite sides are of the same smoothly curved shape, symmetrical about the transverse plane midway along the sides.

Preferably the ends of the crcss-section are also curved. More preferably the junctions of the ends and the sides of the cross-section are also smoothly curved.

The width of the projecting portion of the hook bolt preferably does not increase towards its free end along a circular arc centred on the axis of pivoting of the hook bolt. Preferably that is true for any circular arc that passes through the cross-section of the portion of the hook bolt passing through the opening when the hook bolt is in an extended position. In that way, even when the opening in the casing closely surrounds the hook bolt, the bolt can be moved into and out of its extended position without contact with the surrounding casing. If designing a linearly moveable bolt having a cross-section and opening of the kind defined above, that cross-section can be maintained along the length of the bolt. With a pivotally mounted bolt of the seoond aspect of the invention, however, that is not possible if, as is desired, the opening in the casing is to closely surround the hook bolt when it is in its extended position. If such a cross-section were adopted, then the leading end of the hook bolt would not be able to pass through the casing as it was being moved from its retracted position to its extended position. We have found, however, that by adopting a shape of the kind defined immediately above, movement of the hook bolt between its extended and retracted positions need not be obstructed.

In order to maintain the strength of the hook bolt, it is preferred that the width of the projecting portion of the hook bolt does not reduce substantially, along a circular arc centred on the axis of pivoting of the hook bolt, from the cross-section passing through the opening towards its free end, at least until close to the free end (for example until the last quarter of the length along the arc) We have found that in many conventional lock assemblies, especially multipoint lock assemblies for UPVC docrs, the hook bclt is made with a wider cross-section than is necessary to give it the strength reguired and the casing strength is then correspondingly reduced.

Preferably, the hook bolt of the present invention has a relatively narrow cross-section where in its extended posItion it passes through the opening.

-10 -According to a third aspect of the invention there is provided a multipoint lock assembly including a casing and a latch member mounted for movement between extended and retracted positions, the casing including a front face including an opening to allow movement of a latch member between extended and retracted positions, a first elongate plate mounted over the front face of the casing and a second elongate plate mounted over a front face of the first elongate plate, the first and second plates including TO openings overlying the opening in the front face of the casing.

The first plate preferably extends beyond each of the opposite ends of the casing. Similarly, the second plate preferably extends beyond each of the opposite ends of the casing. The second plate may extend beyond each of the ends of the first plate, as in an embodiment of the invention described below, or the first plate may extend beyond each of the ends of the second plate. With such arrangements both of the first and second plates can be fastened to a door at locations beyond the ends of the casing. The first plate may be dimensioned according to the space available in the vicinity of the look and the second plate may be dimensioned according to the space available further from the lock. Both plates may be of constant cross-section along their length.

While reference is made above to a first plate and a second plate and in an embodiment of the invention described below only two plates are provided, it should be -11 -understood that it is within the scope of the invention for there to be more than two plates. By providing two or more plates instead of a single plate, it becomes possible to select different dimensions and other properties for each of the plates enabling, for example, a wide range of overall thicknesses to be achieved at a low cost.

Preferably the first and second plates are provided at at least one end and more preferably at each end with two openings to allow two fasteners to be passed through the plates at each end for fastening the lock assembly to a door. By providing two fasteners at each end loads transmitted through the plates can be spread.

The first and second plates are preferably fastened to each other at a plurality of locations in addition to being fastened to the casing. Although there are two separate plates it is desirable that they behave to the greatest extent possible as a single plate and therefore it is desirable that they are fastened together in many locations. Since the purpose of the fasteners is in part to spread loads between the two plates, a variety of fasteners may be employed, including fasteners which secure the plates to the casing and fasteners which only secure the plates to one another.

Preferably one of the first and second plates is made of a material harder than the material of the other plate.

This is a further advantage of the invention which saves cost compared to the case where the first and second plates are both made of the harder material. Tn the preferred -12 -arrangement the shorter plate is harder than the longer plate and the cost associated with making the shorter plate harder is reduced.

The present invention further provides a door assembly including a door and a multipoint look assembly as defined above fitted to the door. The lock assembly is preferably arranged to actuate locking members at upper and lower regions of the door and at a mid-height position.

The first and second plates are preferably fastened to TO the door by fasteners positioned beyond opposite ends of the casing. Preferably, two fasteners are positioned beyond each of the opposite ends of the casing, the fasteners passing through the first and second plates and being secured in the door to fix the lock assembly to the door.

According to a fourth aspect of the invention there is provided a handle assembly for operating a latching member, the assembly inotuding a casing, a latching member mounted for movement between extended and retracted positions, a handle mounted for pivoting movement relative to the casing, a resilient biasing assembly including a reciprocatable member and resilient means, a connecting rod pivotally coupled at one end region to the reciprocatable member and at an opposite end region to a member coupled to the handle, whereby rotation of the handle away from a given position in a first direction is resisted by the resilient means.

-13 - ¶Ale have found that the connecting rod and resilient biasing assembly of the fourth aspect of the invention provides a simple and reliable way of resiliently biasing the handle and can be resistant to developing backlash as the parts wear.

Whilst it is within the broadest scope of the invention for the resilient biasing to operate in only one direction of movement of the handle and indeed for the handle to be movable in one direction only, it is preferred that the handle is rotatable in both directions and that rotation of the handle away from the given position in either direction is resisted by the resilient means.

The resilient means preferably comprises a compression spring and the spring is preferably arranged to be compressed by movement of the handle away from the given position in either direction. Using a single spring to oppose movement in both directions is advantageous in reducing the number of parts required. In a preferred arrangement movement of the handle in one direction causes one end of the spring to be moved towards the opposite end which remains stationary, while movement of the handle in the opposite direction causes the opposite end of the spring to be moved towards said one end which remains stationary.

Preferably the resilient means is operative to return the handle to the given position when no external force is applied to the handle.

-14 -The handle assembiLy preferably includes a further handle mounted for pivoting movement relative to the casing about substantially the same axis as the first mentioned handle, a further resilient biasing assembly including a further reciprocatable member and further resilient means, & further connecting rod pivotally coupled at one end region to the further reciprocatable member and at an opposite end region to a further member coupled to the further handle, whereby rotation of the further handle away from a given position in a first direction is resisted by the further resilient means. With such an arrangement each of a pair of handles can be independently operable and independently resiliently biased.

The first mentioned and further connecting rods are preferably positioned alongside one another. Similarly, the first mentioned and further resilient biasing assemblies are preferably positioned alongside one another.

In the case where the resilient biasing means are provided by compression springs they are conveniently provided alongside one another. Such an arrangement is especially compact.

The handle assembly is preferably operative to move a latching member between extended and retracted positions.

The latching member may be a chamfered bolt.

Also according to the fourth aspect of the invention there is provided a handle assembly for operating a latching member, the assembly including a casing, a latching member mounted for movement between extended and -15 -retracted positions, a handle mounted for pivoting movement relative to the casing, a resilient biasing assembly including a reciprocatable member and a compression spring arranged to resist rotation of the handle away from a given position in either direction, the compression spring being arranged to be compressed by movement of the handle away from the given position in either direction. The use of a single compression spring to resist both directions of movement of the handle provides an especially advantageous TO design.

The handle assembly described in the paragraph immediately above may also incorporate any of the features of the previously described handle assembly.

The handle assemblies described above are especially suitable for incorporating in a multipoint lock assembly and the invention also provides a multipoint lock assembly including a handle assembly as defined above.

According to a fifth aspect of the invention there is provided a handle assembly including a casing, a first handle on a first side of the casing and mounted for pivoting movement relative to the casing, a second handle on a second side of the casing and mounted for pivoting movement relative to the casing about the axis of pivoting of the first handle, the first handle being coupled to a first rotary member rotatable with the first handle and carrying a first detachable drive member at a radial spacing from the axis of pivoting of the handles and the second handle being coupled to a second rotary member -16 -rotatabiLe with the second handle and carrying a second detachable drive member at a radial spacing from the axis of pivoting of the handle and on the opposite side of the axis of pivoting to the first detachable drive member, the first and second detachable drive members being operable, when attached and in response to movement of their respective handles, to cause movement of a latching member.

An arrangement of this kind makes it an easy matter to select which handle is operative to drive the latching member and the positioning of the drive members on opposite sides of the axis of pivoting of the handles is advantageous in facilitating a simple and compact design.

In one mode of operation the second detachable drive member is detached and movement of the second handle does not cause movement of the latching member. Similarly, in another mode of operation the first detachabiLe drive member is detached and movement of the first handle does not cause movement of the tatching member.

Preferably the second detachable drive member is positioned diametrically opposite the first detachable drive member.

Each of the drive members preferably comprises a screw threaded shaft and a head. The screw threaded shafts are preferably screwed into their rotary members with the heads upstanding therefrom in opposite directions. The heads of the drive members may then be in substantially the same plane perpendicular to the axis of rotation of the handles.

-17 -Each head is preferably received in a respective arcuate slot formed in a common drive member. The common drive member, which may be of generally lamellar form, is preferably rotatably mounted for rotation about the axis of rotation of the handles to effect movement of the latching member.

For ranges of movements of the handles, the heads of the drive members preferably travel along the arcuate slots and the common drive member is not rotated and, for movements of the handles outside the ranges, the heads of the drive members preferably engage ends of the slots and cause rotation of the common drive member.

In the case where the latch member is chamfered, it is preferably able to be rotated through 180 degrees, for example by unscrewing it, rotating it and screwing it back on.

The handle assembly is preferably operative to move the latching member between extended and retracted positions.

The handle assembly according to the fifth aspect of the invention is especially suitable for incorporating in a multipoint lock assembly and the invention also provides a multipoint lock assembly including a handle assembly according to the fifth aspect of the invention as defined above.

According to a sixth aspect of the invention there is provided a multipoint lock assembly including a casing, a mechanism in the casing for causing linear movement of a -18 -driving member, a mechanism for converting the linear movement of the driving member into linear movements of two lock actuating members in opposite directions, and a deadlocking arrangement acting on the converting mechanism such that in a locked condition of the deadlocking mechanism the converting mechanism prevents linear movements of the two lock actuating members in opposite directions and in the released condition of the deadlocking mechanism the converting mechanism is operative to convert the linear movement of the driving member into linear movements of the two lock actuating members.

The provision of a deadlocking arrangement acting on the motion converting mechanism enhances the security of the lock assembly and is especially advantageous for assemblies where a mechanical key operated mechanism may be replaced, from the outset or as a retrofit, by an electrically operated mechanism. Thus the lock assembly may inciude an etectrically operated mechanism for actuating a latching member.

Preferably one of the two lock actuating members is mounted for movement with the driving member and the other of the two lock actuating members is drivingly coupled to the driving member via a rack and pinion drive. The rack and pinion drive preferably comprises a first rack mounted for linear movement with the driving member, a pinion rotatably mounted alongside the first rack in driven engagement with the first rack and a second rack mounted for linear movement substantially parallel to the linear -19 -movement of the first rack on the opposite side of the pinion to the first rack and in driven engagement with the pinion.

The deadlocking mechanism preferably includes a locking member movable between a locking position in which it engages the second rack to prevent linear movement thereof and a released position in which it allows linear movement of the second rack. The locking member of the deadlocking mechanism is preferably pivotally mounted for TO movement between the locking and released positions. The locking member of the deadlocking arrangement is preferably resiliently biased into the locking position.

The assembly preferably further includes a rotatable handle for moving the lock actuating members, rotation of the handle being operative to pivot the looking member of the deadlocking mechanism from the locking position to the released position. Further rotation of the handle is preferably operative to cause movement of the two lock actuating members in opposite directions.

In the description above six different aspects of the invention have been defined. In a lock assembly described below, all of those features are incorporated in one lock, but it should be understood that it is possible to design a lock assembly incorporating only a single one of the six aspects of the invention, or indeed any number of them.

Also it should be understood that features described either as essential or preferred in respect of one aspect of the invention may also be incorporated, individually or -20 -together with one or more other features from the same or a different aspect of the invention, into one of the other aspects of the invention.

By way of example an embodiment of the invention will now be described with reference to the accompanying drawings, of which: Fig. 1 is an exploded view of a mechanism of a multipoint lock assembly; the mechanism being housed in a casing; Fig. 2k is an isometric view from a first side of the mechanism shown in Fig. 1 with part of the casing omitted in the interests of clarity; Fig. ZR is an isometric view from a second opposite side of the mechanism with part of the casing omitted in the interests of clarity; Fig. 3k is a side view from the first side of the mechanism shown in Figs. 1 and 2, with part of the casing removed, Fig. ZR is a side view from the second side of the mechanism shown in Figs. 1 and 2, with part of the casing removed, Fig. 4k is an exterior side view from a first side of the casing with additional components visible from the exterior of the casing shown; Fig. 4B is a front view of the casing shown in Fig. 4A; Fig. 4C is a side view from a second side of the casing shown in Fig. 4k; -21 -Fig. 4D is an isometric view of a single part of the casing; Fig. 4E is a plan view of a further part of the casing; Fig. 5A is a side view of a hook bolt incorporated in the mechanism; Fig. SB is a cross-sectional view of the hook bolt at the position where it passes out of the casing when in an extended position; Fig. 50 is a side view of the hook bolt shown in Fig. 5A viewed from the opposite side; Fig. SD is a sectional view of the hook bolt along the lines D-D in Fig. 50; Fig. SE is a rear end view of the hook bolt; Fig. SF is a front end view of the hook bolt; Fig. 5G is an isometric view of the hook bolt; Fig. 6A is an isometrio view of a lock assembly incorporating the mechanism of Figs. 1 to 3, also showing front plates for fastening the lock assembly to a door; Fig. 63 is an exploded view of a modified form of the assembly of Fig. 6A; Fig. 7A is a side view of spring assemblies for resiliently biasing handles of the lock assembly; Fig. 7B is a rear view of the spring assemblies shown in Fig. 7A; -22 -Fig. 8 is an isometric view of the lock mechanism including actuating bars for operating bolts at the top and bottom of a door to which the bars are fitted; and Fig. 9 is an isometric view of part of the lock mechanism showing the arrangement for alrering the handing of the mechanism.

Referring first to Figs. 1, 2A, 23, BA and 3B, the assembly shown is a multipoint lock assembly and includes the following major parts: a casing 1 of generally cuboidal form in which the mechanism is housed; a hook bolt 2; a chamfered latch 3; a locking bar 4; a pair of rotatably mounted rotary arms 5A and 53 for engagement by respective handles (not shown) and each rotatable about the common axis of rotation of the handles; an opening 6 in which a key-operated cylinder assembly (not shown) is arranged to be received; a drive member 7 which is rotatably mounted between the rotary arms 5A and SB for rotation about the common axis of rotation of the handles; a pair of spring assemblies BA and SB coupled via respective connecting rods bA and 103 to the rotary arms 5A and 5B respectively; and a rack and pinion arrangement designated generally by reference numeral 11.

In order to assist understanding of particular novel features of the lock assembly, it is convenient first to provide an overview of the general operation of the lock assembly, most of which is known. The lock assembly is mounted on a door at mid-height and operates four locking -23 -or latching members; the hock bolt 2; the chamfered latch 3; and locking members at the top and bottom of the door which are operated by parts driven upwardly and downwardly from the casing. The four locking and latching members are actuated by one or both of a pair of handles (not shown) received in square apertures 12A and 12B in the rotary arms 5A and 53 respectively.

With the parts in the position shown in Figs. 2A, 2B, 3A and 3B, the latching and locking members are all in their extended positions securing the door at each of their locations. In this position, the locking bar 4 is in a lower position and, because the handles are in their rest position, the drive member 7 is in a central neutral position. If now the handle engaging in aperture 12A is rotated anti-clockwise as seen in Figs. 2A and 3A the rotary arm 5A is rotated anti-clockwise raising a projecting lever arm 14A and lowering the connecting rod iDA. As will be explained more fully below, initial movement of the rotary arm 5A is resisted resiliently by the spring assembly 9A but, regardless of the handing of the mechanism (described more fully below), the initial movement does not rotate the drive member 7 but it does move the locking bar 4 upwardly. Assuming the rotary arm 5A is arranged for driving the drive member 7, then upon further rotation of the rotary arm 5A by further turning of the handle, the drive member 7 is rotated anti-clockwise as seen in Figs. 2A and 3A and the top of the drive member 7 camningly engages a rear part of the chamfered latch -24 -assembly retracting the chamfered latch 3 into the casing.

The upward driving cf the locking bar 4 serves to retract the hock bolt 2 from the position shown in Figs. 2A, ZR, 3A and 3B into a pcsitlon in which it is contained wholly within the casing. The movement of the locking bar 4 also rotates via the rack 16 a pinion 17 which in turn drives a rack 18 in the opposite direction to the rack 16. The locking bar 4 carries at its lower end a lower actuating bar 19 (Fig. 8) and the rack 18 is fixed to an upper actuating bar 20 (Fig. 8) . Thus the movement of the locking bar causes movement of the actuating bars 19, 20 inwardly towards the casing causing locking bolts (not shown)at the distal ends of those bars to retract. Thus once the handle has been pivoted fully, all the four latching and locking members are withdrawn.

When the handle is released it returns to its original position as a result of the spring assembly 9A. During the return movement the chamfered latch 3 returns to its extended position, but because there is space below the arm 14A of the rotary arm before any part of the locking bar 4 is engaged, the return movement of the arm HA does not move the looking bar which remains in its relatively high position. Consequently, the hook bolt 2 remains retracted and the actuating bars 19, 20 also remain retracted.

If it is desired to return the latching and locking members to extended positions, then the handle is rotated in the opposite direction (clockwise) rotating the rotary -25 -arm 5A clockwise. Such movement is again resisted by the bias of the spring assembly 9A. Upon rotation against that bias the arm 14A engages the locking bar 4 moving it downwardly back to the position shown in Figs. 2A, 23, 3A and 3B. That movement operates the rack and pinion arrangement 11, extending the actuating bars 19, 20 as well as returning the hook bolt 2 to its extended position. As shown in Fig. 3A, in its extended position, a cam follower part 2A on the hook bolt 2 is engaged in a curved end of a slot 4A of the locking bar 4 so that an external force applied to the hook bolt to move it back towards its retracted position is resisted by engagement of the part 2A with the side of the slot 4A.

In the description above it is assumed that the key-operated cylinder assembly has not been looked. If the cylinder assembly is now rotated through one revolution by a key, then the cam actuator on the cylinder assembly, which is of a standard kind, is rotated one revolution and during its rotation engages a deadlocking mechanism 29 and causes a locking member of the mechanism to engage a recess 29A in the locking bar locking the bar against longitudinal movement. Movement of the locking member into the recess 29A also causes the bottom of an actuating lever 30 to be moved away from the arc of movement of the cam actuator on the cylinder assembly. In this condition the latching and locking members are in their extended positions and are locked against movement out of those positions.

-26 -In order to allow unlocking, a user must insert a key into the cylinder assembly in the opening 6. On turning the key one full revolution the locking member of the deadlocking mechanism 29 is returned to the position shown in Figs 2A, 2B, BA and 3B and the bottom of the actuating lever 30 is returned to a position within range of the arc of movement of the cam actuator on the cylinder assembly.

If the key is then turned through a further full revolution the bottom of the actuating lever is raised, rotating the drive member 7 anti-clockwise as seen in Fig. 3A and retracting the chamfered latch 3. While the locking bar 4 is in the position shown in Figs 1, 2A, 2B, BA and 33, this is of little significance but if the locking bar is moved upwardly causing the hook bolt and other bolts to be retracted, then retraction of the chamfered latch allows the door to be opened.

The basic functions described above are already mostly known. The invention adds various special features which will be described below.

Referring now in particular to Figs. 4A to 4E, further details of the casing 1 will be provided. The casing comprises two principal parts: a main part 1A (referred to also as a single part) and a cover part 13 (referred to also as a further part) The main part 1A, shown in Fig. 4D, has a front face 22, a first side 21 projecting perpendicularly and rearwardly from a first side edge of the front face and a second side 23 opposite the first side 21 and projecting -27 -perpendicularly and rearwardly from a second side edge of the front face 22. The second side 23 extends rearwardly only a small fraction (about one quarter) of the distance that the first side 21 extends rearwardly. The front face 22 of the casing is provided with openings to allow movement of the hook bolt 2 and the chamfered latch 3 between retracted and extended positions. An anti-drill plate 24 is provided on the first side 21 of the casing.

The front face 22 and the second side 23 of the main part lA of the casing do not extend the full length of the casing being absent at each of its opposite ends.

The cover part 1B, shown in Fig. 4E, is of generally lamellar shape and extends rearwardly from the second side 23 to the back of the casing. The cover part 13 is coplanar with the second side 23 of the main part 1A of the casing. An anti-drill plate 25 is provided on the cover part lB opposite the anti-drill plate 24.

The main part 1A is provided with tabs 26 and the cover part lB is provided with tabs 27 which underlie their adjacent parts thus preventing movement of the cover part lb relative to the main part 1A in a direction perpendicular to sides of the casing at their interface.

The cover part 15 is also riveted to the main part 1A at various locations to complete the fixing of the cover part to the main part.

The main part 1A also includes a rear face 28R and opposite end faces 28E so that, with the parts 1A and lB assembled, a casing of cuboidal shape that is substantially -28 -closed except in opposite end regions of its front face is defined.

The book bolt 2 is of a special shape as will now be described with reference to Figs. 5A to 5G. The hook S bolt 2 is rotatably mounted in the casing on a spindle 129, which is received in an opening 129A in the hook bolt, for movement between an extended position, shown in Fig. 5A, in which a projecting portion 30 of the hook bolt projects from the casing 1 and a retracted position, reached by pivoting the bolt clockwise as seen in Fig. 5A in which the bolt is contained within the casing.

Fig. SB is a cross-sectional view of the hook bolt taken in the plane of the front face 22 of the casing. As can be seen, whereas a conventional hook bolt would have a substantially rectangular cross-section in this region, the hook bolt 2 has a cross-section with sides 31 which are smoothly curved such that the overall width of the cross-section is greatest midway along the sides and reduces towards each of the opposite ends 32. The front face 22 of the casing has an opening that is similarly curved and surrounds the hook bolt closely on all sides. In the particular example shown the overall width of the cross-section of the hook bolt is about 5 mm at its midway point and there is a spacing of only about 1 mm between the hook bolt and the casing where the bolt passes through the front face 22 of the casing.

A complication arises because the hook bolt 2, despite its curved cross-section must be retractable into the -29 -casing. This is achieved by ensuring that the width of the projecting portion 30 does not increase towards its free end 32 along any circular arc centred on the axis of the spindle 129. Thus, for example, in Fig. 5A, a circular arc A is marked; at the place where this arc cuts through the front face 22 of the casing the hook bolt has a particular overall width w. That width w does not increase along the arc A in the direction towards the free end 32 of the hook bolt 2. It does, however, remain substantially the same width until close to the free end so that the hook bolt 2 is strong even near its free end. The free end 32 is chamfered to a reduced width so as to assist with extending of the bolt into an opening when perfect alignment with a door frame is not achieved prior to the pivoting of the bolt 2 into its extended position.

The shape of the hook boit 2 is further shown in Figs. 5C to 5G of the accompanying drawings.

Referring now to Fig. 6A, the lock casing 1 is shown fixed to two elongate plates 51 and 52. The plate 51 is mounted over the front face 22 of the casing 1 and is in contact therewith. The plate 52 is mounted over the front face of the plate 51 and is in contact therewith. As can be seen from Fig. GA the plate 51 itself projects beyond the ends of the casing 1 but terminates at ends referenced 51E in Fig. GA. The plate 51 is much longer and it extends at both ends beyond the bounds of Fig. GA. Also visible in Fig. 6A are the actuating bars 19, 20 which are disposed -30 -behind the plates 51 and 52 and also extend beyond the bounds of Fig.6A.

The elongate plates 51 and 52 are secured in use to a door by two bolts 53k and 533 which are disposed just beyond the ends of the casing 1, and by two further bolts 54A and 543 which are disposed further from the ends of the casing 1 but inside the ends 51E of the plate 51.

The four bolts pass through ciroular openings in the plates 51 and 52 and through elongate slots in the actuating bars 19 and 20 and secure the plates to the door.

Screws 55 secure the plates 51 and 52 to the casing 1 and there are also fixing pins 56 that pass through the plates 51 and 52 only and secure them to one another.

By forming the plates 51 and 52 separately it becomes a very simple matter to make them of different materials and/or of different dimensions enabling the maximum strength to be obtained for a given oost and size of plates.

Fig. 63 shows a modified version of the arrangement shown in Fig. 6A. In Fig. 63 the shorter plate 51 of hardened material is placed outside the longer plate 52, the ends of which are not visible in Fig. 63. In Fig. 63 corresponding parts are referenced by the same numerals as in Fig. 6A. As will be understood, in the assembled state of the arrangement shown in Fig. 63 the shorter plate 51 lies over the front of the longer plate 52 in contact therewith.

-31 -In the lock assembly shown in the drawings a special arrangement is employed to bias each of the handles into its usual rest position. Substantially the same arrangement is used for each handle; initially the arrangement for the S handle received in the aperture 123 of the rotary arm 53 will be described particularly with reference to Figs. 7A and 73. The rotary arm 53 is pivotally connected, at a position away from its axis of rotation, to a lower end of the connecting rod 103. The upper end of the connecting rod 103 is pivotally connected to the bottom of a rod 413 which forms part of the spring assembly 93. When the rotary arm SB is rotated anti-clockwise as seen in Fig. 7A, the rod 413 is driven upwardly by the connecting rod 103 and this in turn drives a stop 423 upwardly compressing a compression spring 433 between the stop 423 and the bottom of a cylinder 443 in which the rod 413 is slidably received. When the rotary arm 53 is rotated clockwise as seen in Fig. 7A, the rod 413 is pulled downwardly by the connecting rod 103 and this in turn drives a stop 453 downwards, in turn driving the cylinder 44B downwards and compressing the compression spring 433 between the bottom of the cylinder 44B and the stop 423. Thus for each direction of rotation of the arm 53, the compression spring 433 is compressed, in one case by raising of its lower end and in the other case by lowering of its upper end.

As will now be understood and as shown in Fig. 78, the arm SA operates in substantially the same way with the -32 -connecting rod iDA and the spring assembly 9A. Also, it may be seen that the connecting rods iDA and 103 and the spring assemblies 9A and 9B are placed alongside one another in the casing 1.

Another special arrangement in the lock assembly is the arrangement employed to change the handing of the lock.

As will be understood, according to which is the exterior side and interior side of a door to which the lock is fitted, so it may be desired to alter the functions provided by the handles. Such "handing" of locks is well known but the illustrated assembly incorporates a new method of providing the handing. In the drawings each of the rotary arms 5A and 5B is shown with a respective drive member S1A and 513. As most clearly seen in Fig. 9, the drive members 51A and 51B project from their respective rotary arms in opposite directions with the result that although the rotary arms are provided in planes that are offset from one another on opposite sides of the drive member 7, the heads of the drive members 51A and SiB are copanar and are received in respective arcuate slots 52A and 523 provided on diametrically opposite sides of the axis of rotation of the drive member 7. Each of the drive members has a screw threaded shaft and is screwed into its respective rotary arm. Therefore, if it is required to disconnect the drive from one of the handles to the drive member 7, all that is required is to unscrew whichever of the drive members 51A and SiB is appropriate. This provides a very simple way of adjusting the handing of the -33 -lock assembly. When the handing of the lock is selected, it is also necessary to place the chamfer of the chamfered latch 3 on the correct side; for this purpose the head of the latch 3 may be unscrewed, rotated through 180 degrees S and screwed back into position.

In operation, when a rotary arm 5A or SB is rotated and a drive member 51A or 518 is carried on the arm, it will initially simply slide in the arcuate slot 52A or 52B and the drive member 7 will not be rotated. Upon further rotation of the rotary arm 511 or 53, however, the drive member 5111 or 518 will reach the end of the slot and will then begin to rotate the drive member 7.

The general functioning of the rack and pinion drive 11 has already been described and is conventional.

The drive 11 does, however, include a special deadlocking arrangement employing a pawl 15, as will now be described.

The pawl 15 is pivotally mounted on a spindle 60 and is pivotabiLe between a locking position shown in the drawings, in which upward movement of the rack 16 into its top position, in which the actuating bars 19, 20 are retracted and the hook bolt 2 is retracted, is prevented by engagement of a hook 61 at the top of the pawl with a corresponding projection 62 on the back of the rack 16.

When, however, the rotary arm SB is turned clockwise (as seen in for example Figs. 33 and 9), the stop 45B is pulled down and the stop cammingly engages the pawl 15 via a ball bearing (not visible in the drawings) rotating it against a resilient bias clockwise (as seen in for example Figs. 3B -34 -and 9) , retracting the hook 61 out of the path of the projection 62 so that the rack 16 is free to be driven into its top position. As will be understood if instead the stop 45A is pulled down, it similarly will cammingly engage the pawl 15 rotating it against its resilient bias to retract the hook 62.

This extra deadlocking feature of the mechanism is of only limited value in the case where the lock in the opening 6 is a mechanical key-operated look, but it becomes more significant if that lock is replaced by an electrically operated mechanism since that may require disabling of the deadlocking mechanism 29.

Claims (1)

1. <claim-text>-35 -Otaims 1. A lock assembly including: a lock casing; a hook bolt pivotally mounted in the lock casing for pivoting movement between an extended position in which a portion of the hook bolt projects through an opening in a front face of the casing and a retracted position in which the projecting portion of the bolt is contained at least substantially within the casing; wherein, when the hock bolt is in an extended position, the cross-section of the portion of the hook bolt passing through the opening in the front face of the casing is of a generally elongate shape having an overall width measured between opposite sides of the cross-section in a first direction parallel to the axis of pivoting of the hook bolt that is less than an overall length measured between opposite ends of the cross-section in a second direction perpendicular to the first direction, wherein the overall width of the cross-section is greatest in a middle portion of the cross-section spaced from each of its ends and the overall width reduces towards each of the ends of the cross section, and wherein the sides of the cross-section are adjacent to the boundary of the opening in the front face of the casing.</claim-text> <claim-text>2. A lock assembly according to claim 1, in which the sides of the cross-section are adjacent to the boundary of -36 -the opening in the front face of the casing along substantially the whole length of each side.</claim-text> <claim-text>3. A lock assembly according to claim 1 or 2, in which the ends of the cross-section are adjacent to the boundary of the opening in the front face of the casing 4. A lock assembly according to any preceding claim, in which the overall width of the cross-section is greatest midway along the sides of the cross-section.5. A lock assembly according to any of any preceding claim, in which the sides of the cross-section are smoothly curved.6. A lock assembly according to any preceding claim, in which the width of the projecting portion of the hook bolt does not increase towards its free end along a circular arc centred on the axis of pivoting of the hook bolt.7. A lock assembly according to any preceding claim, in which the cross-section is substantially as herein described with reference to Fig. SB of the accompanying drawings.</claim-text>