A MORTICE LOCK WITH A REVERSIBLE LATCH BOLT

Abstract

 A mortice lock (1) with a housing (2) having a non-circular opening (13) and a latch bolt (3) with a longitudinal axis (9). The latch bolt (3) has a main portion (10) received in the non-circular opening (13) to prevent the latch bolt (3) from turning around its longitudinal axis (9). The lock (1) further comprises a guiding mechanism which enables pushing the latch bolt (3) inside the lock (1) into a position in which the main portion (10) is disengaged from the non-circular opening (13) and the latch bolt (3) can be reversed easily between a left-handed and a right-handed position without having to remove a front wall of the housing (2) and without having to release the latch bolt (3) to remove it from the lock (1).

Description

[0001] The present invention relates to a mortice lock with a reversible latch bolt. The lock comprises a housing provided with a non-circular opening and a latch bolt having a longitudinal axis. The latch bolt has a main portion having a non-circular cross-section, which main portion is received in said non-circular opening to guide the latch bolt and to prevent it from turning around its longitudinal axis during operation. The latch bolt is reversible between a left-handed and a right-handed position by turning it around its longitudinal axis. The lock further comprises a guiding mechanism for the latch bolt enabling a reciprocating sliding movement of the latch bolt along its longitudinal axis between an extended and a retracted position, which guiding mechanism comprises said non-circular opening in the housing and a further guide provided in the housing. The lock also comprises at least one latch bolt spring to urge the latch bolt towards its extended position and an actuation mechanism arranged to move said latch bolt from said extended to said retracted position against the latch bolt spring.

[0002] EP 2 186 974 discloses such a mortice lock in which the latch bolt is reversible. A drawback of this type of locks is that the latch bolt is only reversible when a part of the front plate or the entire front plate of the lock, which comprises the non-circular opening, is removed thereby allowing to turn the latch bolt around its longitudinal axis. However, removing the front plate of a lock is time consuming and a removable front plate has to be sufficiently strong, as such it requires more material, in particular stainless steel. Thus, a removable front plate increases the costs for manufacturing the lock. Moreover, when the lock has already been mounted in the mortice, removing the front plate also entails having to remove the lock from the mortice which is time consuming. Further, it is also possible that during removal of the front plate, one or more of the screws attaching the front plate are lost due to carelessness of the person removing the front plate.

[0003] Mortice locks with reversible latch bolts for which the front wall does not have to removed are also known in the state of the art. For example, GB 2 439 783 discloses a mortice lock with a rectangular latch bolt which latch bolt can be pulled out of the housing. By pulling out the latch bolt it is possible for the latch bolt to be turned between a left-handed and a right-handed position before being inserted back into the lock. A disadvantage of such locks is that more complicated internal mechanisms are needed that enable releasing the latch bolt from its guiding mechanism thereby enabling to take the latch bolt out of the housing, thus increasing the costs of the lock. Moreover, the more complicated internal mechanisms also increase the chance of a malfunction of the lock and as such these locks are less reliable.

[0004] It is an aim of the present invention to provide a mortice lock wherein the latch bolt can be reversed easily between a left-handed and a right-handed position without having to remove the front wall and without having to release the latch bolt and remove it from the lock.

[0005] This aim is achieved according to the invention with a guiding mechanism which enables to slide the latch bolt in the direction of its longitudinal axis against the latch bolt spring into a position wherein its main portion is disengaged from said non-circular opening and wherein the latch bolt is reversible by turning it around its longitudinal axis between said left-handed and right-handed position.

[0006] By pushing the latch bolt into the housing until its main portion is disengaged from the non-circular opening the latch bolt is no longer prevented from turning around its longitudinal axis so that the latch bolt can be easily turned from said left-handed to right-handed position and vice versa. Moreover, there is no need for an internal mechanism allowing to release the latch bolt or the front plate. As such, there is also no need to reinsert the latch bolt or reattach the front plate in a correct manner.

[0007] EP 2 778 323 discloses a lock for mounting into a tubular member, which has a latch bolt that is also reversible without having to remove the front wall or without having to remove the latch bolt from the housing. However, this latch bolt is a cylindrical latch bolt which is reversible in all of its positions (e.g. the extended and retracted positions). A disadvantage of such a lock is that the latch bolt can be turned when the gate is closed by inserting a pair of pliers between the gate and the tubular member and simply turning the latch bolt. Reversing the latch bolt when the gate is closed enables to open the gate by pushing against the gate as the latch bolt penetrates only with its bevelled top in the lock keep. A lock according to the present invention does not have this drawback since the lock has a latch bolt with its main portion having a non-circular cross-section.

[0008] In an embodiment of the present invention the lock further comprises a retainer which is irrotatably mounted in the housing and which is resiliently urged against said main portion of the latch bolt at least when said main portion is in its disengaged position and which is urged away from the centre of the latch bolt when the latch bolt is turned from its left-handed position to its right-handed position and vice versa.

[0009] This embodiment has the advantage that the retainer prevents an accidental rotation of the latch bolt during normal use. For example, it could be that due to an excessive force applied to the latch bolt during normal operation, e.g. slamming a gate shut, the latch bolt is pushed into the disengaged position and rotates to a small extent. This would then lead to a jammed latch bolt and a non-functional lock. The retainer prevents this from happening by resiliently urging against the main portion to prevent such an accidental rotation.

[0010] Preferably, said retainer comprises a ring portion extending around the latch bolt and at least one lip portion having a proximal end attached to the ring portion and a distal end which is resiliently urged against the main portion of the latch bolt. In particular, said lip portion is resiliently bent away from the centre of the latch bolt when said latch bolt is turned from its left-handed position to its right-handed position and vice versa.

[0011] The ring portion of the retainer fits around the latch bolt so that the latch bolt is always centred with respect to the retainer. The lip portion remains continuously in contact with the latch bolt during the reciprocating sliding movement of the latch bolt thereby always urging the latch bolt to remain in either the left-handed or the right-handed position. Further, as the lip portion bends resiliently outwards it also remains continuously in contact with the main portion of the latch bolt during rotation of the latch bolt. Moreover, when the latch bolt is turned from a right-handed to a left-handed position the lip portion starts urging the latch bolt to its left-handed position when the left-handed position is nearly reached. In fact, the urging of the lip portion ensures that the latch bolt snaps into its left-handed position when it is nearly reached thereby ensuring that the person reversing the latch bolt does not have to be very accurate.

[0012] In a preferred embodiment of the present invention said non-circular opening has an edge comprising at least two straight sections and the main portion of the latch bolt comprises at least two flat sides corresponding to these at least two straight sections. In particular, said at least one lip portion is resiliently urged against one of said at least two flat sides in the left-handed position and against the other one of said at least two flat sides in the right-handed position. The flat sides act as the urging point of the at least one lip portion and the lip portion can correspondingly urge against a different flat side depending on the right-handed or left-handed position of the latch bolt.

[0013] Preferably, one of said two flat sides is used to effect closure of the gate by abutting with a gate keep when the latch bolt is in the right-handed position, while the other one of said two flat sides is used to effect closure of the gate by abutting with a gate catcher when the latch bolt is in the left-handed position.

[0014] In a further preferred embodiment, said actuation mechanism comprises a stopping element which abuts against an element in the housing when the actuation mechanism slides the latch bolt into its retracted position and which prevents the actuation mechanism from sliding the latch bolt beyond its retracted position into its disengaged position.

[0015] In this further preferred embodiment, the latch bolt does not enter its disengaged position by actuating the actuation mechanism, i.e. during daily use of the lock. As such, this provides an additional safety measure to prevent accidental rotation of the latch bolt as it cannot reach its disengaged position by the actuation mechanism. Therefore, there is a smaller chance that the latch bolt can get stuck by an accidental rotation in its disengaged position.

[0016] In an advantageous embodiment, said latch bolt comprises a back portion irrotatably arranged in said further guide and rotatably connected to the main portion of the latch bolt. In particular, the actuation mechanism comprises a lever which engages the back portion of the latch bolt to slide the latch bolt from its extended to its retracted position.

[0017] In this advantageous embodiment, the main portion is free to rotate with respect to the back portion when it is in its disengaged position and it is not necessary to rotate the entire latch bolt but only the main portion of the latch bolt. Moreover, the lever engages with the back portion and does not need to account for differences in operation between the right-handed and the left-handed position of the main portion of the latch bolt.

[0018] Preferably, said latch bolt further comprises a connecting portion which connects the main portion to the back portion, the connecting portion being screwed to said main portion and rotatably connected to said back portion and comprising a screw thread configured to cooperate with a further screw thread arranged on the main portion of the latch bolt, which screw thread and further screw thread enable adjusting the distance between said main portion and said back portion. As the distance between the main portion and the back portion of the latch bolt is adjustable it is possible to compensate for a larger or a smaller distance between a closure member, wherein the lock has been placed, and a gate keep.

[0019] More preferably, the latch bolt comprises a hole extending from its front surface to the connecting portion enabling to rotate the connecting portion with respect to the main portion through the hole. As the hole is provided in the front surface of the latch bolt, the distance between the main portion and the back portion can be adjusted at any time when the closure member is open, even after the lock has been placed in a mortice, without having to open the housing of the lock or without having to remove the lock.

[0020] The invention will be further elucidated by means of the following description and the appended figures.

Figure 1 shows a perspective view of a mortice lock according to the present invention and a closure member provided with a mortice wherein the lock is to be mounted.

Figure 2 shows a same perspective view as Figure 1 with the lock mounted in the closure member.

Figure 3 shows an exploded view of a portion of the mortice lock of Figure 1.

Figure 4 shows a perspective view of the mortice lock of Figure 1 on a larger scale, with a portion of the lock being cut away with the latch bolt in the extended position.

Figure 5 is a detail of Figure 4 and shows the lip portion of the retainer urging against the main portion of the latch bolt and the lever engaging the back portion of the latch bolt.

Figures 6 and 7 show the same views as Figures 4 and 5 but with the latch bolt in the retracted position.

Figures 8 and 9 show a perspective view of the mortice lock similar to Figures 6 and 7 but seen from the other side.

Figures 10 and 11 show the same views as Figures 4 and 5 but showing a cross-section of the latch bolt.

Figures 12 to 15 illustrate how the main portion of the latch bolt is turned from its left-handed to its right-handed position.

Figure 16 shows a perspective view of a mortice lock according to the present invention without a retainer.

Figure 17 shows a perspective view of the mortice lock of Figure 18 with the latch bolt in the disengaged position and slightly turned about its longitudinal axis so that the latch bolt is stuck behind the front plate.

Figure 18 shows a front view of the mortice lock of Figure 19 indicating the slight rotation of the latch bolt.

[0021] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting.

[0022] The invention generally relates to a mortice lock 1 comprising a housing 2 and a reversible latch bolt 3. The term mortice lock is used to indicate that the lock is to be inserted in a mortice, i.e. a recess in a door or an opening in a tubular member. The closure member is a hinged closure member which is fixed by means of hinges to a support.

[0023] The mortice lock 1 of the present invention is configured to be mounted through a slot 4 in a wall portion of a tubular member 5. This tubular member 5 can be part of a gate, for example as illustrated in Figures 1 and 2.

[0024] The lock 1 may comprise a deadbolt 6 which is operated by means of a key, in particular through the intermediary of a lock cylinder. Usually the deadbolt 6 is slidably mounted in the lock 1 to slide between a retracted and an extended position. In the embodiments illustrated in the drawings, the deadbolt 6 is however hook-shaped and pivots in the lock 1 between its extended and its retracted position. This type of deadbolt 6 is already known from the prior art. Reference can be made to the lock disclosed in EP 2 186 974 which is incorporated herein by way of reference.

[0025] The lock 1 comprises, besides the housing 2 and the latch bolt 3, a guiding mechanism for the latch bolt 3, a latch bolt spring 7, and a latch bolt actuation mechanism 8. The latch bolt 3 has a longitudinal axis 9. The latch bolt 3 can be a one-piece structure, but a latch bolt 3 comprising a main portion 10 and a back portion 11, which can rotate with respect to one another, is preferred. In a two-piece latch bolt 3 the back portion 11 can help guide the latch bolt 3. More preferably, the latch bolt 3 also comprises a connecting portion 12. The three-part structure of the latch bolt 3 enables to adjust the distance between the main portion 9 and the back portion 11 as will be detailed below. The housing 2, the latch bolt 3, and the deadbolt 6 are preferably made from stainless steel.

[0026] The guiding mechanism of the latch bolt 3 is formed by a non-circular opening 13 in the housing 2 which receives the main portion 9 of the latch bolt and two elongated slots 14 in the housing which each receive a part of the back portion 11 of the latch bolt 3. Figures 6 and 8 show the lock 1 from opposite perspective views and each view shows one of the two elongated slots 14 in the housing 2. The guiding mechanism enables a reciprocating sliding movement of the latch bolt 3 along its longitudinal axis 9 between an extended, a retracted, and a disengaged position. The extended position of the latch bolt 3 is shown in Figures 4 and 5, while the retracted position of the latch bolt 3 is shown in Figures 6 and 7, and the disengaged position is shown in Figure 12.

[0027] As can be seen from Figures 4 and 6 the actuation mechanism 8 is turned, e.g. by turning a handle (not shown) inserted in the actuation mechanism 8, which in turn displaces a latch bolt lever 26. The latch bolt lever 26 is arranged to engage with the back portion 11 of the latch bolt 3 and slides the back portion 11 into the housing thereby sliding the entire latch bolt 3. The actuation mechanism 8 comprises an arm 27 which rotates together with the actuation mechanism 8 and abuts with a retainer a pin 18 inserted in a retainer 17, discussed below. Because the arm 27 abuts with the pin 18 the actuation mechanism 8 cannot slide the latch bolt 3 beyond this point. In other words, the arm 27 functions as a stop of the actuation mechanism 8 thereby defining the retracted position of the latch bolt 3. This stopping function of the arm 27 could also be achieved with a differently orientated arm abutting against an element, not necessarily the pin 18, in the housing 2. For example, the arm 27 could abut against a ridge inside the housing 2. As such, the travel distance of the back portion 11 between the extended and the retracted position is determined by the position wherein the arm 27 abuts with the retainer 17. Therefore, during normal operation of the actuation mechanism 8 the latch bolt 3 does not reach its disengaged position and thus cannot rotate with respect to its longitudinal axis 9.

[0028] However, as can be seen from Figure 7, when the latch bolt 3 is in the retracted position there is still some room between the back portion 11 and the end of the elongated slots 14. This added room is provided so that the latch bolt 3 can be pushed into its disengaged position, shown in detail in Figure 14. As such, the disengaged position of the latch bolt 3 is deeper in the housing 2 than its retracted position. Moreover, the total travel distance of the back portion 11 is limited by the length of the elongated slots 14 and is between 10 and 30 mm, preferably around 20 mm. Further, the distance between the back end of the elongated slots 14 and the back portion 11 in the retracted position is between 0.5 and 3 mm, preferably around 1.5 mm (compare Figures 7 and 14).

[0029] As shown in Figure 3, the housing 2 comprises a non-circular opening 13. In the embodiments shown in the drawings the non-circular opening 13 has an edge comprising at least two straight sections 15 and the main portion 10 of the latch bolt 3 has a corresponding non-circular cross-section having two flat sides 16. It is also possible to have differently shaped cross-sections of the main portion 10 of the latch bolt 3, e.g. hexagonal, only one flat side, circular with a groove or extension, etc. However, it is advantageous to have at least two flat sides 16 on opposite sides of the latch bolt 3, which flat sides are oriented vertically. When the lock 1 is inserted in a tubular member 5 there is normally a corresponding gate keep mounted on a support. When the closure member is closed the main portion 10 of the latch bolt 3 extends into the gate keep thus effecting closure of the closure member. It is beneficial to have a flat side 16 of the latch bolt 3 that abuts with a flat side of the gate keep. As the lock 1 of the present invention has a reversible latch bolt 3 it is beneficial to have at least two flat sides 16 so that one of said two flat sides 16 abuts with the gate keep in the right-handed position of the latch bolt 3 and the other one of said two flat sides 16 abuts with a gate keep in the left-handed position of the latch bolt 3. To prevent rotation of the latch bolt 3, the non-circular opening 13 preferably has a corresponding shape to the main portion 10 of the latch bolt 3. However, the non-circular opening 13 could also prevent rotation of the latch bolt 3 with only one flat section 15, but this would leave space between the latch bolt 3 and the non-circular opening 13 allowing dirt, e.g. sand, water, etc. to enter the housing 2.

[0030] As can be seen from Figures 10 and 11 for example, the latch bolt spring 7 urges the latch bolt 3 towards its extended position. As this is the normal operation of a latch bolt spring, no further details are necessary to understand its operation. Moreover, as described above, the actuation mechanism 8 is used to move said latch bolt 3 from said extended to said retracted position against the latch bolt spring 7. Again, the workings of this type of actuation mechanisms 8 is known in the prior art and need not be discussed further.

[0031] Figure 16 shows a lock 1 according to an embodiment of the present invention. Figures 17 and 18 illustrate a possible malfunction of this embodiment. The latch bolt 3 is in its disengaged position and has rotated a small amount around its longitudinal axis 9 but not enough to turn be in either the left-handed or the right-handed position. This slight rotation can happen accidently, e.g. when a closure member is slammed shut and the latch bolt 3 moves into the disengaged position due to the force of slamming the closure member. As the latch bolt 3 is not in either one of the left-handed or the right-handed position the main portion 10 of the latch bolt 3 cannot re-engage with non-circular opening 13. Thus the latch bolt 3 is stuck inside the housing 2.

[0032] To prevent this possible malfunction, in a preferred embodiment of the present invention, the lock 1 further comprises a retainer 17, as shown in Figures 3 to 15. The retainer 17 has an overall cuboid shape ensuring that it is irrotatably mounted in the housing 2. Moreover, to ensure fixation of the retainer 17 with respect to the housing 2, the retainer 17 is fixed to the housing using a pin 18 inserted through an opening in the retainer 17 and two corresponding openings (not shown) in the housing 2. The retainer 17 is further fixed to the housing using a second pin 19. As can be seen from Figure 6 for example, the retainer 17 is mounted adjacent to the non-circular opening 13 in the housing 2. Moreover, the lever 26 of the actuation mechanism 8 also abuts with the retainer 17 in the extended position, as illustrated in Figure 5.

[0033] The retainer 17 comprises a ring-shaped opening 20 through which the latch bolt 3 slides and two lips 21. The lips 21 each have a proximal end attached to the ring-shaped opening 20 and a distal end urging against the flat sides 16 of the latch bolt 3. As can be seen from the exploded view in Figure 3, the lips 21 extend from their proximal end to their distal end substantially parallel to said longitudinal axis 9. The ring-shaped opening 20 ensures that the retainer 17 is always centred around the main portion 10 and thus the lips 21 are always in contact with the flat sides 16.

[0034] As can be seen from Figures 12 and 17 for example and as discussed above, the latch bolt 3 can be pushed against the latch bolt spring 7 into a position wherein its main portion 10 is disengaged from said non-circular opening 13 and wherein the main portion 10 of the latch bolt 3 is reversible between a left-handed and a right-handed position by turning it around its longitudinal axis 9.

[0035] Figures 12, 13 and 15 illustrate how the main portion 10 of the latch bolt 3 is turned from a left-handed to a right-handed position, while Figure 14 shows a detailed view of the latch bolt 3 in an intermediate position. The first step in turning the latch bolt 3 is to insert an external tool 22, for example an Allen key, in an opening 23 in the front surface of the latch bolt 3. The tool 22 grips in a hexagonal socket 28 shown in Figure 11. By pushing on the external tool 22 the latch bolt 3 is slidable into its disengaged position wherein the main portion 10 is pushed completely into the housing 2 thereby disengaging the main portion 10 from the non-circular opening 13. As shown in Figures 6 and 8, one of the lips 21 is always urging against one of the flat sides 16 of the main portion 3, even in the disengaged position. This lip 21 prevents accidental rotation of the main portion 10. However, when using the external tool 22 to rotate the main portion 10 bends the lips 21 away from the centre of the latch bolt 3. This is clearly shown in Figure 14, which show one of the lips 21 bending outwards when the main portion 10 of the latch bolt 3 is in an intermediate position between the left-handed and the right-handed position. When continuing the turning motion of the main portion 10 using the external tool 22 the main portion 10 can be rotated the full 180 degrees thereby reversing the latch bolt 3. As can be seen from Figure 15 the lip 21 that was initially urging against the flat side 16 is now free in the disengaged position, however the lip 21 on the other side of the latch bolt 3 is now urging against the other flat side 16 to prevent accidental rotation of the main portion 10 of the latch bolt 3. When removing the external tool 22 the main portion 10 of the latch bolt 3 will reengage with the non-circular opening 13 and the latch bolt 3 has been reversed.

[0036] By this simple push-turn-release method the latch bolt 3 is reversible at any time either before or after having inserted the lock 1 into the tubular member 5 when the closure member is not in the closed position. Moreover, the entire operation takes only a few seconds to execute.

[0037] It would also be possible to have only one lip 21 but this would entail that the lip 21 needs to position further inside the housing 2 as the one lip 21 needs to be urging against one of the flat sides 16 of the main portion 10 in both the right-handed and the left-handed position and also in the extended, retracted, and disengaged positions of the main portion 10 of the latch bolt 3. Placing the retainer 17 further inwards inside the housing 2 limits the distance the latch bolt lever 26 can move and thus limits the travel distance of the latch bolt 3. As the lock 1 preferably fits into a tubular member 5 having an inner width (w) less than 40 mm there is not enough room to place the retainer 17 further inwards in the housing 2. It would also be possible to provide a retainer 17 having a spring mechanism to urge a flat section of the retainer against the flat sides 16 of the main portion 10 of the latch bolt 3. However, such a delicate and small spring mechanism would be hard to manufacture and thus more expensive. Moreover, such a small and delicate mechanism could easily malfunction.

[0038] As discussed above, in a preferred embodiment of the present invention, the latch bolt 3 comprises a main portion 10, a back portion 11, and a connecting portion 12. The separate portions are shown in the exploded view of Figure 3, while a cross-sectional view is shown in Figures 10 and 11. As shown in Figure 3, the back portion 11 has an opening which allows the back portion 3 to be placed on the connecting portion 12. Once the back portion 11 is placed on the connecting portion 12, the connecting portion 12 is partly flanged thereby rotatably mounting the back portion 11 on the connecting portion 12. As shown in Figure 3, the top part of the connecting portion 12 has a screw thread 24 which cooperates with a further screw thread 25 on the inside of the main portion 10. By inserting a tool, for example an Allen key, in the opening 23 it is possible to rotate the connecting portion 12 with respect to the back portion 11. The tool now grips on the hexagonal socket 29 shown in Figure 11. To allow the connecting portion 11 to be rotated by a tool gripping on the hexagonal socket 29 the diameter of the circumscribed circle around the hexagonal socket 29 needs to be smaller than the diameter of the inscribed circle of the hexagonal socket 28 to allow the tool to rotate inside the hexagonal socket 28. By the cooperating screw threads 24, 25 and the main portion 10 being prevented to rotate due to the guiding mechanism, the main portion 10 will slide with respect to the connecting and back portions 11, 12. As such, the distance between the main and back portions 10, 11 can be adjusted. Note that, to allow the latch bolt 3 to enter its disengaged position the main portion 10 needs to be fully retracted with respect to the back portion 11, otherwise the back portion 11 will abut against the end of the elongated slots 14 and the main portion 10 will not be disengaged from the non-circular opening 13.

[0039] As can be seen from Figures 1 and 2, the lock 1 is arranged to be mounted in a square tubular member 5. As this type of lock 1 is designed for closure members, such as a gate e.g. in a garden fence, the lock 1 preferably fits into a square tubular member 5 having an inner width of less than 40 mm. Of course, the lock 1 can also be used in rectangular tubular members 5 which have a larger inner width. Moreover, as the tubular member 5 has a square cross-section the distance between the side walls of the housing 2 also has be less than 40 mm to fit in a tubular member 5 of 40 mm. This certainly has to hold for the area near the main portion 10 of the latch bolt 3. As the main portion 10 of the latch bolt 3 actually effects closure of the closure member, as discussed above, the main portion 10 needs to be as strong as possible and thus have as large a diameter as possible. Therefore, the housing 2 has, at the location of the main portion 10, an inner width between 5% and 30% and preferably between 10% and 20% larger than the diameter of the circumscribed circle around the main portion 10 of the latch bolt 3. This fractionally larger distance enables the main portion 10 of the latch bolt 3 to rotate inside the housing 2 and allows the retainer 17 to be placed around the main portion 10, which as discussed above helps the function of the lips 21 in preventing an accidental rotation of the main portion 10 of the latch bolt 3. Furthermore, in order to have a strong main portion 10 the flat sides 16 need to be as minimal as possible, because a circular main portion 10 is stronger than a non-circular main portion 10. Therefore, the diameter of the circumscribed circle around the main portion 10 of the latch bolt 3 is between 5% and 35% and preferably between 10% and 25% larger than the diameter of the inscribed circle in the main portion 10 of the latch bolt 3.

Claims

1. A mortice lock (1) with a reversible latch bolt (3), the lock (1) comprising:

- a housing (2) provided with a non-circular opening (13);

- a latch bolt (3) having a longitudinal axis (9) and a main portion (10) having a non-circular cross-section, which main portion (10) is received in said non-circular opening (13) to guide the latch bolt (3) and to prevent it from turning around its longitudinal axis (9) during operation and which latch bolt (3) is reversible between a left-handed and a right-handed position by turning it around its longitudinal axis (9);

- a guiding mechanism for the latch bolt (3) enabling a reciprocating sliding movement of the latch bolt (3) along its longitudinal axis (9) between an extended and a retracted position, which guiding mechanism comprises said non-circular opening (13) in the housing (2) and a further guide (14) provided in the housing (2);

- at least one latch bolt spring (7) to urge the latch bolt (3) towards its extended position; and

- an actuation mechanism (8) arranged to move said latch bolt (3) from said extended to said retracted position against the latch bolt spring (7),

characterised in that
said guiding mechanism enables to slide the latch bolt (3) in the direction of its longitudinal axis (9) against the latch bolt spring (7) into a position wherein its main portion (10) is disengaged from said non-circular opening (13) and wherein the latch bolt (3) is reversible by turning it around its longitudinal axis between said left-handed and right-handed position.

2. A mortice lock (1) according to claim 1, characterised in that the lock (1) further comprises a retainer (17) which is irrotatably mounted in the housing (2) and which is resiliently urged against said main portion (10) of the latch bolt (3) at least when said main portion (10) is in its disengaged position and which is urged away from the centre of the latch bolt (3) when the latch bolt (3) is turned from its left-handed position to its right-handed position and vice versa.

3. A mortice lock (1) according to claim 2, characterised in that said retainer (17) comprises a ring portion (20) extending around the latch bolt (3) and at least one lip portion (21) having a proximal end attached to the ring portion (20) and a distal end which is resiliently urged against the main portion (10) of the latch bolt (3).

4. A mortice lock (1) according to claim 3, characterised in that said lip portion (21) extends from its proximal end to its distal end substantially parallel to said longitudinal axis (9).

5. A mortice lock (1) according to claim 3 or 4, characterised in that said lip portion (21) is resiliently bent away from the centre of the latch bolt (3) when said latch bolt (3) is turned from its left-handed position to its right-handed position and vice versa.

6. A mortice lock (1) according to any one of the claims 2 to 5, characterised in that said non-circular opening (13) has an edge comprising at least two straight sections (15), the main portion (10) of the latch bolt (3) comprises at least two flat sides (16) corresponding to these at least two straight sections (15), and said at least one lip portion (21) is resiliently urged against one of said at least two flat sides (16) in the left-handed position and against the other one of said at least two flat sides (16) in the right-handed position.

7. A mortice lock (1) according to any one of the claims 2 to 6, characterised in that said non-circular opening (13) is provided in a front wall of the housing (2) and said retainer (17) is arranged in the housing (2) just behind its front wall.

8. A mortice lock (1) according to any one of the preceding claims, characterised in that said actuation mechanism (8) comprises a stopping element (27) which abuts against an element (17) in the housing (2) when the actuation mechanism (8) slides the latch bolt (3) into its retracted position and which prevents the actuation mechanism (8) from sliding the latch bolt (3) into its disengaged position.

9. A mortice lock (1) according to any one of the preceding claims, characterised in that said latch bolt (3) comprises a back portion (11) irrotatably arranged in said further guide (14) and rotatably connected to the main portion (10) of the latch bolt (3).

10. A mortice lock (1) according to claim 9, characterised in that said latch bolt (3) further comprises a connecting portion (12) which connects the main portion (10) to the back portion (11), the connecting portion (12) being screwed to said main portion (10) and rotatably connected to said back portion (11) and comprising a screw thread (24) configured to cooperate with a further screw thread (25) arranged on the main portion (10) of the latch bolt (3), which screw thread (24) and further screw thread (25) enable adjusting the distance between said main portion (10) and said back portion (11).

11. A mortice lock (1) according to claim 10, characterised in that the latch bolt (3) comprises a hole (23) extending from its front surface to the connecting portion (12) enabling to rotate the connecting portion (12) with respect to the main portion (10) through the hole (23).

12. A mortice lock (1) according to any one of the preceding claims, characterised in that said non-circular opening (13) has an edge comprising at least two straight sections (15) and the main portion (10) of the latch bolt (3) comprises at least two flat sides (16) corresponding to these at least two straight sections (15).

13. A mortice lock (1) according to any one of the preceding claims, characterised in that the diameter (D) of the circumscribed circle (30) around said main portion (10) of said latch bolt (3) is between 5% and 35% and preferably between 10% and 25% larger than the diameter (d) of the inscribed circle (31) in said main portion (10) of said latch bolt (3).

14. A mortice lock (1) according to any one of the preceding claims, characterised in that said housing (2) has, at the location of the main portion (10), an inner width (w) between 5% and 30% and preferably between 10% and 20% larger than the diameter (D) of the circumscribed circle (30) around said main portion (10) of said latch bolt (3).

15. A mortice lock (1) according to any one of the preceding claims, characterised in that said lock (1) fits into a square tubular member (5) having an inner width (W) of less than 40 mm.

Drawing