AU2012258464B2

AU2012258464B2 - Self Latching Lock

Info

Publication number: AU2012258464B2
Application number: AU2012258464A
Authority: AU
Inventors: Owen Wiseman
Original assignee: Lietzke Australia Pty Ltd
Current assignee: Lietzke Australia Pty Ltd
Priority date: 2005-10-14
Filing date: 2012-12-03
Publication date: 2014-05-29
Anticipated expiration: 2026-09-20
Also published as: AU2012258464A1

Abstract

A self-latching lock (100) for a door (1) is disclosed. The lock comprises a lock mechanism (18-24) for moving a lock member (4A,B) into a door locking position when the door has moved to a closed position. The lock further comprises a trip mechanism 5 (9-13) for activating the lock mechanism to enable the movement of the lock member into the door locking position. The trip mechanism comprises an activation mechanism (9,11) for movement between an inactive position, and an active position in which the lock mechanism is activated for moving the lock member into the door locking position. The trip mechanism further comprises a retention mechanism (10, 10A, 12, 10 13) for retaining the activation mechanism in the inactive position when the door is open but which is arranged to allow the activation mechanism to move to the active position when the door has moved to the closed position.

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: RIVERS LOCKING SYSTEMS (AUSTRALIA) PTY LTD A.C.N. 066 391 419 Invention Title: SELF LATCHING LOCK The following statement is a full description of this invention, including the best method of performing it known to us: -2 Self-Latching Lock Technical Field A self-latching lock for a door is disclosed. The self-latching lock finds particular though not exclusive use with fire doors. 5 Background Art A requirement for fire doors is that they be self-closing and self-latching (see e.g. Australian Standard AS1905.2). In other words, after being opened, the fire door needs to automatically move into the closed position and latch shut. Known latch mechanisms for fire doors (often referred to as a "lockset") have a 10 tapered tongue that is designed, as the door is closed, to retract and latch when the tongue comes into contact with a striker plate located on a door jamb. From a security perspective, the tapered tongue represents a weakness in that it may readily be prised open with an appropriately shaped tool by an intruder or the like. In the application of AS1905.2, the use of more secure locking bolt 15 arrangements has generally been restricted, as these may prevent a fire door from being opened during an emergency. Summary In a first aspect there is provided a self-latching lock for a door. The lock comprises a lock mechanism. The lock mechanism comprises two lock members located in an 20 opposing relationship in the lock. The lock mechanism is adapted such that it is able to move each lock member into a respective door locking position when the door has moved to a closed position. The lock also comprises a trip mechanism for activating the lock mechanism to enable the movement of the lock member into the door locking position. The trip mechanism comprises an activation mechanism for 25 movement between an inactive position, and an active position in which the lock mechanism is activated for moving the lock member into the door locking position. The trip mechanism also comprises a retention mechanism for retaining the activation -3 mechanism in the inactive position when the door is open but arranged to allow the activation mechanism to move to the active position when the door has moved to the closed position. A lock configured in this manner can self-latch, and yet can be easily unlocked, 5 opened and can then automatically be reconfigured for self-latching once again. Also, such a lock can readily be configured such that, when the door is open, the lock members are not left extending from the lock. Thus, when the door returns to the closed position the lock members are already retracted and do not prevent door closing by interfering with the door frame (i.e. the door self-latches only once tripped 10 by the trip mechanism). In a usual configuration, movement of the lock members out of the door locking position enables opening of the door. The trip mechanism may then be configured such that, with door opening, the activation mechanism is caused to move to the inactive position, and the retention mechanism is caused to retain the 15 activation mechanism in the inactive position. This enables the lock members to be retained in an unlocked state after door opening, until the door is again closed (e.g. by a door self-closing mechanism). The activation mechanism can be caused to move to the inactive position by a first biasing device. The retention mechanism can be caused to retain the activation 20 mechanism in the inactive position by being moved into engagement with the activation mechanism by a second biasing device. Each such biasing device can then be arranged such that they are unable to effect such movements when the door is closed. In one embodiment the retention mechanism comprises a release latch which can be caused by the second biasing device to latchingly retain the activation 25 mechanism in the inactive position. A protruding free end of the release latch may then be arranged to engage a striker located in a jamb for the door when the door is closed. When such engagement occurs, the release latch can be moved to overcome the action of the second biasing device and to disengage from the activation mechanism, thus releasing the activation mechanism for movement from the inactive -4 position to the active position. In other words, a simple mechanism can be provided that makes use of a striker to initiate the trip mechanism. In one embodiment the activation mechanism may comprise a rod that is adapted at a free end thereof to also engage the doorjamb striker. Thus, when the 5 door is closed and the release latch has been moved by the door jamb striker to release the activation mechanism, engagement of the rod free end with the door jamb striker can move the rod to overcome the action of the first biasing device and into the active position, whereby the lock mechanism can then be activated. Again, a simple mechanism can be provided that makes use of the striker to initiate the trip 10 mechanism. The adaptation of the rod free end may comprise an enlarged mounting shaped to engage the door jamb striker. For example, the enlarged mounting may be a round-headed nut, the nut being adjustable on a threaded end of the rod for fine tuning of the trip mechanism. Further, the round head facilitates movement of the nut 15 along the striker and assists with release latch movement back past and over the nut after door unlocking and opening. The second biasing device may comprise a spring that acts on the release latch in a manner that causes the release latch to pivot into inter-engagement with the rod adjacent to the enlarged mounting. This inter-engagement can retain the rod in the 20 inactive position until the door is closed. For example, the release latch can latchingly sit behind a shoulder of the round-headed nut. The activation mechanism can further comprise a catch that is arranged to engage the lock mechanism and prevent it from being activated. Thus, when the rod moves into the active position, it can act against the catch to move it out of 25 engagement with the lock mechanism, thereby activating the lock mechanism to move the lock members into the door locking position. The first biasing device may also be a spring. This spring can act on a first push bar extending between the rod and the catch. The spring and first push bar may be arranged such that the rod is biased into the inactive position by the spring acting on -5 the first push bar. At the same time, the catch can be biased into engagement with a component of the lock mechanism also by the spring acting on the first push bar. This double action of the spring can simplify the lock construction. The component may be defined by a second push bar connected to the lock 5 members. In addition, a third biasing device can be provided to act on the component to urge the lock members into the door locking position when the door has moved to the closed position. Further, the trip mechanism can be arranged to prevent such urging by the third biasing device when the door is other than closed. An adjustment bar may be positioned between and so as to connect the 10 second push bar to the lock member, with the adjustment bar being configured to enable the overall length of the second push bar/adjustment bar/lock member to be varied. This length variation enables the lock to be used with different width doors. Also, the third biasing device may be a spring that is connected to act on the adjustment bar. 15 A handle can be provided for manual opening of the door. In this regard, the handle can manually act on the lock mechanism to cause the lock members to move out of the door locking position and into a door unlocked position, whilst the door is in the closed position. This can then free the door for opening. This easy release of the lock is to be contrasted with known latch mechanisms for fire doors which can pose a 20 significant problem in that the fire door being locked shut in a fire situation. In one form the handle is rotatably mounted to a housing for the lock and the lock mechanism may then be located in the housing. The arrangement may be such that, once the handle has been rotated to move the lock members out of the door locking position, and once the door is opened, the lock mechanism is then acted upon 25 by the trip mechanism to retain the lock members in the door unlocked position, thus ensuring that it will self-latch when closed again (e.g. by a door closer mechanism). The handle can be connected to a cam of the lock mechanism. The cam can then rotate with rotation of the handle. The cam may further be connected to the second push bar via a link bar to translate handle rotational movement to the lock -6 members. A fourth biasing device (e.g. a spring) can be connected to the link bar such that, when the door is closed and the trip mechanism activates the lock mechanism, the link bar is acted upon by the fourth biasing device to assist with lock member extension and also to return the handle to a position whereby it can be used to unlock 5 the door. An over-centre retention configuration between the link bar and the cam may be employed in this regard. In one form the rod free end can be located outside of the housing to easily engage the door jamb striker when the door is closed. An opposite end of the rod can be located inside the housing to activate the lock mechanism when the door is closed. 10 The housing may comprise two parts, with one part interleaved and telescopically received in the other part to thereby enable the overall length of the housing to be varied. This variation is typically in accordance with a corresponding variation in the overall length of the second push bar/adjustment bar/lock members, pursuant to the lock being employed on different width doors. Alternatively, the lock 15 mechanism may comprise four lock members, with one or two lock members being located in the lock in an opposing relationship to the other three or two lock members respectively. In this case, the lock mechanism may be adapted such that each member is moved by the lock mechanism into a respective door locking position when the door has moved to the closed position. 20 In one usual form, the lock mechanism is housed within an elongate housing that is adapted for mounting transversely across the door in use. Each lock member may then protrude from a respective housing end when in the door locking position. The lock can be configured for mounting to a face of the door, for example, an inside surface of the door that faces onto a secure space. In this regard, the housing 25 can be adapted for mounting to the door face (e.g. by being screwed or bolted thereto and then covered with a secure faceplate). In a second aspect there is provided a self-latching lock for a door, the lock comprising: -7 - a lock mechanism for moving two or more lock members from a door unlocked position and into a door locked position when the door is moved to a closed position, the two or more lock members being located in an opposing relationship in the lock; and 5 - a trip mechanism for activating the lock mechanism to enable the movement of the lock members into the door locked position, the trip mechanism being adapted for retaining the lock mechanism in the door unlocked position when the door is open but arranged to be tripped when the door is moved to the closed position to thereby enable the lock mechanism to move the lock members into the door locked position. 10 The self-latching lock may comprise two lock members in which case each lock member can be located to project in use from a respective door side in the door locked position. This can be referred to as a two-point lock. Alternatively, the self-latching lock may comprise three lock members in which case two lock members can be located to project in use from one door side, and the 15 other lock member can be located to project in use from the other door side in the door locked position. This can be referred to as a three-point lock. In a further alternative the self-latching lock may comprise four lock members in which case, in the door locked position: - two lock members can be located to project in use from one door side, and the other 20 two lock members can be located to project in use from the other door side; or - three lock members can be located to project in use from one door side, and the other lock member can be located to project in use from the other door side. These arrangements can each be referred to as a four-point lock. The self-latching lock of the second aspect may otherwise be defined as in the 25 first aspect. Brief Description of the Drawings -8 Notwithstanding any other forms which may fall within the scope of the self latching lock as defined in the Summary, specific embodiments of the lock will now be described, by way of example only, with reference to the accompanying drawings in which: 5 Figure 1 shows a perspective view of an assembled self-latching lock on a door; Figure 2 shows a schematic plan view of the assembled self-latching lock on the door, together with a detail of a surrounding door frame; Figures 3-1, 3-2, 3-3 and 3-4 respectively show, in four steps and in schematic plan, a detail of the self-latching lock on the door, and a surrounding door frame 10 detail, with the lock being in progressive stages of non-latching to self-latching; Figures 4 (i) and (ii) respectively show side and front sectional detail views of the self-latching lock; Figure 5 shows a reverse front (underside) view of the self-latching lock in a door-locked configuration; 15 Figure 6 shows a reverse front (underside) view of the self-latching lock in a door-open configuration; and Figure 7 shows a front view of the self-latching lock in a door-locked configuration, but illustrating manual door opening. 20 Detailed Description of Specific Embodiments Referring to Figures 1 to 7 a so-called 2-point configuration of a self-latching lock is depicted (i.e. two latching points as a result of two locking bars in the lock). However, it should be noted that the functionality of the self-latching mechanism is no different for a 4-point configuration (e.g. that has four latching points resulting from 25 four locking bars) In a most typical 4-point configuration, three locking bars at one end of the lock and one locking bar at the other end, more typically with one latching point at the hinge jamb of the door frame and three latching points on the opposite jamb.

-9 Figures 1 and 2 show a typical location of a multiple-point self-latching (MPSL) lock (100) on a door leaf (1). The MPSL lock is shown as mounted to a face of the door leaf (e.g. an inside door surface facing a secure floor). The external mounting is simple to fit or retrofit to doors, especially fire doors. However, it should be appreciated that 5 the lock can be incorporated or integrated into the door. Also, it should be appreciated that the lock can extend vertically whereby latching then occurs in a head of the door frame and/or a recess in the adjacent floor. Figure 1 shows the door in an open position, and Figure 2 shows the door in a closed position with the MPSL lock latched. Figure 2 also illustrates a typical location 10 of door inside and door outside. The MPSL lock is used with a doorset that comprises a door leaf (1). The MPSL lock body (2) is mounted onto the face of the door leaf (1) via nut plates (3), acorn nuts (3A) and threaded rod (3B), with the plate (3) and rod (3B) passing through the door leaf (1) and through fixing tubes (27) mounted in the lock body (2). 15 Locking bars (4) that extend from the lock body (2) are received into a metal door frame (5), extending either through keeper plates (6) or through slots defined in the frame (5), to lock the door closed in use. When the door is in the closed position, the locking bars (4) are disengaged from the keeper plates (6) by manually rotating a lock handle (7). As shown in Figures 20 5 to 7, the manual rotation of the lock handle (7), downwards and anti-clockwise through 90 degrees, causes the locking bars (4) to be fully retracted and disengaged from the keeper plates (6), thus allowing the door leaf (1) to be opened. When an opposite handedness is required, the handle can be rotated in a clockwise direction through 90 degrees to cause the locking bars to be fully retracted and disengaged 25 from the keeper plates. Referring to Figure 2, the MPSL lock can be provided with a key operated lock (eg. accessed from an outside location). In this regard, the handle can be connected to a commercially available lock cylinder contained within a cylinder shield (8) and linked to the handle (7) via the lock internal mechanism within the lock body (2). In - 10 applications where no key access is provided from a location outside, the door can then only be opened from an inside location through manual turning of the handle (7). Referring now to Figure 3, a four-step closing operation of the MPSL lock will now be described, with the depicted steps 1, 2, 3 and 4 showing a detail of the door 5 leaf (1) and lock mechanism in progressive stages of closing. Step 4 further shows the locking bars (4) having latched into the keep plates (6) fitted to the metal door frame (5). Figure 3, Step 1 shows the doorset with the door leaf (1) in a slightly ajar, open position moving towards a door closed position. In this configuration, the locking bars 10 (4) are fully retracted into the lock body (2), and the lock handle (7) projects downwardly (having been previously moved down into the open position as a result of a previous door opening). The MPSL lock comprises a trip mechanism including a trip rod (9) that in Step 1 is caused to extend to a full extent away from the lock body (2), whereby the trip rod 15 (9) is in a so-called "inactive position". The trip mechanism further comprises a release latch (10) that sits behind and retains a trip rod adjustment nut (11) mounted at the end of the trip rod (9). This configuration maintains the trip rod (9) in the inactive position, and ensures that the rod is not accidentally activated (eg. bumped or pushed by persons using the door). 20 Digressing now to Figure 4, it will be seen that the release latch (10) is held in position through the combined action of a bush (12) and release latch spring (13). The release latch spring (13) is connected for operation between the bush (12) and latch (10), and ensures that part of a projecting portion (10A) of the latch (10) remains engaged behind the trip rod adjustment nut (11) when the door leaf (1) is opened. For 25 the trip rod (9) to move out of the inactive position, it must move along its axis towards the lock body (2). This can only occur if the release latch projecting portion (10A) is rotated out of the way of the trip rod adjustment nut (11). Returning to Figure 3, Steps 2 and 3 depict the two actions that are required to activate the self-latching mechanism of the MPSL lock. These are: - 11 1. The release latch (10) is rotated against the action of spring (13) to cause it to disengage from its retained location behind the trip rod adjustment nut (11). 2. The trip rod (9) is then urged in a direction along its axis, towards 5 and into the lock body (2). Figure 3, Step 2 depicts the action of the door leaf (1) moving into the closed position. This closing brings the projecting end (10A) of release latch (10) into contact with a chamfered face of an activation striker (14) mounted on the door frame (5). This action causes the release latch (10) to pivot around its axis, along a centre line 10 through bush (12) and against the action of release latch spring (13). This pivoting continues as the door leaf (1) continues to close. Eventually the release latch projecting portion (10A) disengages from nut (11), thereby freeing the trip rod (9) to move along its axis. Figure 3, Step 3 depicts the action of the door leaf (1) moving further into the 15 closed position. Now a rounded end of the trip rod adjustment nut (11) comes into contact with the chamfered face of the activation striker (14). With continued door closing the nut (11) rides along the chamfered face of the activation striker (14) causing the trip rod (9) to be progressively urged along its axis towards and into the lock body (2) and against the action of a biasing device (described below). 20 Figure 3, Step 4 depicts the door leaf (1) in the closed position. The trip rod (9) has now been fully urged along its axis towards and into the lock body (2). In this regard, the trip rod (9) is now in a so-called "active position". In addition, a mechanism for releasing the locking bars (4A,4B) has now been activated, so that these bars now project out from the lock body (2) and into the metal door frame (5), extending either 25 through keeper plates (6) or through slots defined in the frame (5). This now locks (self-latches) the door closed. The length of the trip rod (9) can be adjusted for fine-tuning of the trip mechanism through the screwing/unscrewing of trip rod adjustment nut (11). As indicated by Figure 3 - Step 4, the correct adjustment of nut (11) ensures that the - 12 release of the locking bars (4) coincides with the door leaf (1) reaching the closed position and, at the same time, the locking bars (4) latching into the keeper plates (6) fitted to the metal door frame (5). The mechanism for releasing the locking bars (4A,4B) will now be described 5 with reference to Figures 5 to 7. Figure 5 shows a reverse view, revealing the internal mechanism of the MPSL lock in the "closed position". Figure 6 shows a reverse view, revealing internal mechanism of the MPSL lock in the "open position". Figure 7 shows a front external view of the MPSL lock, and depicts the action of retracting the locking bars (4A,4B) by manually rotating the lock handle (7) through 90 degrees. 10 Referring to Figure 5, the movement of the trip rod (9) along its axis and into the lock body (2) has pushed an end (9A) of rod (9) against a latch lever (15). The latch lever is connected to a catch (15A) which is pivotally mounted within the lock body (2). Thus, the movement of rod (9) causes the lever (15) and catch (15A) to pivot and release a catch end (15B) from a latch slot (17) of a lock release mechanism. In this 15 regard, the latch slot (17) is defined in a push bar (18), with bar (18) being indirectly connected to the locking bars (4A,4B). Figure 5 shows the catch end (15B) having become disengaged from the latch slot (17). A locking bar spring (19) that is connected to operate between the lock body (2) and an adjusting push bar (20) has caused the push bar (18) to be shifted laterally 20 (to the right in Figure 5). The adjusting push bar (20) extends between and connects the push bar (18) and the locking bar (4A). When the catch end (15B) disengages from the latch slot (17), the potential energy associated with the spring (19) is released. The spring (19) contracts, thereby causing the lateral movement of the push bar (20). This action urges both locking bars 25 (4A,4B) into the lock body (2), as shown in Figure 5, with locking bar 4B being retracted via mechanical linkages (described below). Guided movement of the locking bars (4A,4B) is facilitated by locking bar guide sleeves (26) mounted to the lock body (2) The sleeves slidingly support the bars (4A,4B) and also maintain locking bar orientation in use and overtime.

- 13 Whilst the lateral movement of the adjusting push bar (20) directly moves the locking bar (4A) through its direct connection thereto, the same action also causes lateral movement of the push bar (18). This action in turn pulls on a link bar (21A) to which the push bar (18) is pivotally connected. The link bar (21A) is at an opposite end 5 pivotally connected to an end of a pivot cam (22), with the cam being pivotally mounted to the lock body (2). Thus, the pulling action on the link bar (21A) rotates the pivot cam (22) about its axis. The rotation of the pivot cam (22) is assisted by a link bar spring (23) extending between the lock body (2) and the link bar (21A). Pivoting of cam (22) releases the 10 potential energy of the link bar spring (23), with such energy being translated by the cam to assist in pushing on a second link bar (21B). The second link bar (21B) is directly and pivotally connected to an end of the second locking bar (4B) so that when it is pushed by the cam (as shown in Figure 5) it moves the locking bar (4B) out of the lock body (2). The pivoting of cam (22) also rotates the lock handle (7) which is connected 15 to the cam (22), returning the handle to a laterally extending (ready-to-open) position shown in Figure 7. To open the door leaf (1) the locking bars (4) need to be disengaged from the keeper plates (6) fitted to the metal door frame (5). This is achieved by manually turning the lock handle (7) (as depicted in Figure 7). Because the handle (7) is 20 connected to the cam (22) its turning rotates the cam (22). Rotation of the cam (22) stretches the link bar spring (23) and, through the mechanical action and interconnection of the link bars (21), push bar (18) and adjusting push bar (20), the locking bars (4) are retracted into the lock body (2). As the locking bars (4) retract, the locking bar spring (19) is also stretched, again generating potential energy in this 25 spring. The lock handle (7) is designed to rotate through 90 degrees to fully retract the locking bars (4). At the point of full retraction, and with the door leaf (1) now open (at least to the point of Figure 3 - Step 1) the catch end (15B) of latch lever (15) is now aligned to latchingly engage with the latch slot (17). The latch lever (15) pivots into - 14 latching engagement with the action thereon of the latch lever spring (16). The spring (16) also maintains the latch lever with catch (15B) in place. As the latch lever (15) pivots into latching engagement it pushes against the trip rod (9), urging it along its axis and out of the lock body (2). Thus, the latch lever 5 spring (16) has a two-fold effect, in that it urges the latch lever (15) into latching engagement with the latch slot (17), and it urges the trip rod (9) into its inactive, outwardly extended position. Now that the door leaf (1) is open, this allows the release latch (10) to rotate about its common axis with bush (12), through the action of the release latch spring 10 (13). The latch projecting portion (10A) now engages with and behind the trip rod adjustment nut (11). With the release latch (10) engaged with nut (11) the trip rod (9) now cannot move back along its axis toward the lock body (2) and hence the locking bars (4) are now "locked" or retained open, even should lock handle (7) be inadvertently knocked or bumped when the door leaf (1) is open. 15 The overall length of the MPSL lock can be adjusted to suit differing door widths. In this regard, the lock body (2) may comprise two interleaved parts (2A,2B) telescoped together. Prior to mounting the MPSL lock to a door leaf, the overall length of lock body (2) is fixed by drilling self-tapping screws (24) through both prior-adjusted and interleaved parts (2A,2B). 20 The internal linkages of the MPSL lock can then be adjusted to suit the selected length of the lock body (2). In this regard, the adjusting push bar (20) is typically a sleeve that can be slid over the push bar (18). Once at the desired overall length, a cup head screw (25) is inserted through the appropriate hole in the adjusting push bar (20) and into a corresponding aligned hole in the push bar (18). 25 Whilst the MPSL lock described has been designed to self-latch to specifically meet the requirements of Australian Standard AS1905.2, it can be used for any standard doorset that requires a self-latching lock.

- 15 The self-latching function is optimally employed with a hinged door that automatically moves into a door closed position after it has been opened, whereby the lock will then self-latch. Such an automatic closing action of the door is usually performed through the use of a door closer. However, the MPSL lock is not limited to 5 such applications. The MPSL lock is configured such that, when the door (1) is opened, the locking bars (4) are not left extending from the lock body (2). Thus, when the door (1) returns to the closed position the locking bars (4) are already retracted and do not prevent the door from closing by interfering with the door frame (5). The MPSL lock self-latches 10 only once tripped by the trip mechanism. The easy handle release of the MPSL lock is to be contrasted with many known latch mechanisms, especially for fire doors. Some such mechanisms can be locked to then remain locked, and can thus pose a significant problem in that the fire door can remain locked shut in a fire situation. 15 The MPSL lock can be provided in 2-point and 4-point configurations. 4-point configurations are typically employed where extra security is required. A typical 4 point configuration employed has one latching point at the hinge jamb of the door frame and three latching points on the opposite jamb. In its simplest form, however, the lock may comprise a single-point configuration. 20 The MPSL lock finds particular application with fire doors, but it should be appreciated that the lock is not limited to this application. Doors may also be purpose built, modified or retro-fitted to place them in an optimal form for use with the MPSL lock. For example, special striker and self-closing components can be provided in a lockset that is then mounted to the door frame and door, together with the MPSL 25 lock. The MPSL lock can also be used for two doors, where the lock is mounted vertically on an active door leaf and latching occurs into a door frame head and/or floor (eg. into a floor cup). Then the two doors can be locked together through eg. two pivoting locking bars received into receiving cups mounted on the inactive door leaf.

- 16 The MPSL lock provides two separate but integrated mechanical movements for the lock to self-latch. This avoids accidental activation of the lock. Whilst the self-latching lock has been described with reference to particular embodiments, it should be appreciated that the lock can be embodied in many other 5 forms.

Claims

1. A self-latching lock for a door, the lock comprising: - a lock mechanism that comprises two lock members located in an opposing relationship in the lock, the lock mechanism being adapted such that it is able to move 5 each lock member into a respective door locking position when the door has moved to a closed position; and - a trip mechanism for activating the lock mechanism to enable the movement of the lock members into the door locking position, the trip mechanism comprising: - an activation mechanism for movement between an inactive position, and an 10 active position in which the lock mechanism is activated for moving the lock member into the door locking position; and - a retention mechanism for retaining the activation mechanism in the inactive position when the door is open but arranged to allow the activation mechanism to move to the active position when the door has moved to the 15 closed position.

2. A lock as claimed in claim 1 wherein movement of the lock members out of the door locking position enables opening of the door, and wherein the trip mechanism is configured such that, with door opening, the activation mechanism is caused to move to the inactive position, and the retention mechanism is caused to 20 retain the activation mechanism in the inactive position.

3. A lock as claimed in claim 2 wherein the activation mechanism is caused to move to the inactive position by a first biasing device, and the retention mechanism is caused to retain the activation mechanism in the inactive position by being moved into engagement with the activation mechanism by a second biasing device, with each 25 such biasing device being unable to effect such movements when the door is closed.

4. A lock as claimed in claim 3 wherein the retention mechanism comprises a release latch which is caused by the second biasing device to latchingly - 18 retain the activation mechanism in the inactive position, with a protruding free end of the release latch being arranged to engage a striker located in a jamb for the door when the door is closed whereby, when such engagement occurs, the release latch is moved to overcome the action of the second biasing device and to disengage from the 5 activation mechanism, thus releasing the activation mechanism for movement from the inactive position to the active position.

5. A lock as claimed in claim 4 wherein the activation mechanism comprises a rod that is adapted at a free end thereof to also engage the doorjamb striker whereby, when the door is closed and the release latch has been moved by the 10 door jamb striker to release the activation mechanism, engagement of the rod free end with the door jamb striker moves the rod to overcome the action of the first biasing device and into the active position whereby the lock mechanism is activated.

6. A lock as claimed in claim 5 wherein the adaptation of the rod free end comprises an enlarged mounting shaped to engage the door jamb striker. 15

7. A lock as claimed in claim 6 wherein the second biasing device is a spring that acts on the release latch in a manner that causes the release latch to pivot into inter-engagement with the rod adjacent to the enlarged mounting, thereby retaining the rod in the inactive position until the door is closed.

8. A lock as claimed in any one of claims 5 to 7 wherein the activation 20 mechanism further comprises a catch that is arranged to engage the lock mechanism and prevent it from being activated, and wherein, when the rod moves into the active position, it acts against the catch to move it out of engagement with the lock mechanism, thereby activating the lock mechanism to move the lock members into the door locking position. 25

9. A lock as claimed in claim 8 wherein the first biasing device is a spring that acts on a first push bar extending between the rod and the catch, the spring and first push bar being arranged such that the rod is biased into the inactive position by the spring acting on the first push bar and the catch is biased into engagement with a component of the lock mechanism also by the spring acting on the first push bar. - 19

10. A lock as claimed in claim 9 wherein the component is a second push bar connected to the lock members.

11. A lock as claimed in claim 10 wherein a third biasing device is provided to act on the component to urge the lock members into the door locking position 5 when the door has moved to the closed position, whereby the trip mechanism is arranged to prevent such urging by the third biasing device when the door is other than closed.

12. A lock as claimed in claim 10 or 11 wherein an adjustment bar is positioned between and so as to connect the second push bar to the lock members, 10 with the adjustment bar being configured to enable the overall length of the second push bar/adjustment bar/lock member to be varied.

13. A lock as claimed in claim 12 wherein the third biasing device is a spring that is connected to act on the adjustment bar.

14. A lock as claimed in any one of the preceding claims wherein a handle is 15 provided to manually act on the lock mechanism and cause the lock members to move out of the door locking position and into a door unlocked position whilst the door is in the closed position.

15. A lock as claimed in claim 14 wherein the handle is rotatably mounted to a housing for the lock, with the lock mechanism being located in the housing and 20 adapted such that, once the handle has been rotated to move the lock members out of the door locking position, and once the door is opened, the lock mechanism is then acted upon by the trip mechanism to retain the lock member in the door unlocked position.

16. A lock as claimed in claim 15 when dependant on any one of claims 10 25 to 13 wherein the handle is connected to a cam of the lock mechanism such that the cam rotates with rotation of the handle, the cam being connected to the second push bar via a link bar to translate handle rotational movement to the lock members, with a fourth biasing device being connected to the link bar such that, when the door is - 20 closed and the trip mechanism activates the lock mechanism, the link bar is acted upon by the fourth biasing device to assist with lock member extension and also to return the handle to a position whereby it can be used to unlock the door.

17. A lock as claimed in claim 16 wherein the fourth biasing device is a 5 spring.

18. A lock as claimed in any one of claims 15 to 17, when dependant on any one of claims 5 to 13, wherein the rod free end is located outside of the housing for engaging the door jamb striker when the door is closed, with an opposite end of the rod located inside the housing to activate the lock mechanism when the door is 10 closed.

19. A lock as claimed in any one of claims 15 to 17, when in turn dependant on claim 12, wherein the housing comprises two parts, with one part interleaved and telescopically received in the other part to thereby enable the overall length of the housing to be varied in accordance with a corresponding variation in the overall length 15 of the second push bar/adjustment bar/lock members.

20. A lock as claimed in any one of claims 1 to 19 wherein the lock mechanism comprises four lock members, with either one or two lock members being located in the lock in an opposing relationship to the other three or two lock members respectively, the lock mechanism being adapted such that each member is moved by 20 the lock mechanism into a respective door locking position when the door has moved to the closed position.

21. A lock as claimed in claim 20, wherein the lock mechanism is housed within an elongate housing that is adapted for mounting transversely across the door in use, with each lock member protruding from a respective housing end when in the 25 door locking position.

22. A lock as claimed in any one of the preceding claims that is configured for mounting to a face of the door. - 21

23. A lock as claimed in claim 23 when dependant on any one of claims 15 to 19 or 22, wherein the housing is adapted for mounting to the door face.

24. A self-latching lock for a door, the lock comprising: - a lock mechanism for moving two or more lock members from a door unlocked 5 position and into a door locked position when the door is moved to a closed position, the two or more lock members being located in an opposing relationship in the lock; and - a trip mechanism for activating the lock mechanism to enable the movement of the lock members into the door locked position, the trip mechanism being adapted for 10 retaining the lock mechanism in the door unlocked position when the door is open but arranged to be tripped when the door is moved to the closed position to thereby enable the lock mechanism to move the lock members into the door locked position.

25. A lock as claimed in claim 24 comprising two opposing lock members wherein each lock member is located to project in use from a respective door side in 15 the door locked position.

26. A lock as claimed in claim 24 comprising three lock members wherein two lock members are located to project in use from one door side, and the other lock member is oppositely located to project in use from the other door side in the door locked position. 20

27. A lock as claimed in claim 24 comprising four lock members wherein, in the door locked position: - three lock members are located to project in use from one door side, and the other lock member is oppositely located to project in use from the other door side; or 25 - two lock members are located to project in use from one door side, and the other two lock members are oppositely located to project in use from the other door side. - 22

28. A lock as claimed in any one of claims 24 to 27 that is otherwise as defined in any one of claims 1 to 23.

29. A self-latching lock substantially as herein described with reference to the accompanying drawings. 5

30. A door that is mounted or fitted with, that is modified for and/or that is suitable for the self-latching lock as defined in any one of the preceding claims.