Magnetic latch for fastening a hinged closure member to a support

Abstract

A magnetic latch for fastening a closure member to a support. The magnetic latch comprises a keeper assembly including a magnet and a latch bolt assembly having: an elongated frame (32); a latch bolt (14) moveable between a latching position and a retracted position; a latch bolt biasing member urging the latch bolt into its retracted position; and a latch bolt operating mechanism configured to move the latch bolt from its latching position to its retracted position against a magnetic attraction. The latch bolt operating mechanism comprises: an effort link rod (37); a load link rod (34); and a second-order lever (35) interposed between the effort link rod and the load link rod. The second-order lever reduces the force required to operate the latch bolt operating mechanism thus allowing for an increased magnetic attraction of the latch bolt towards the magnet in the keeper assembly.

Claims

1. A magnetic latch for fastening a closure member to a support, the magnetic latch comprising a latch bolt assembly configured to be mounted to one of the closure member and the support and a keeper assembly configured to be mounted to the other one of the closure member and the support, the keeper assembly comprising a first magnetic element and the latch bolt assembly comprising: an elongated frame extending in a vertical direction and having two opposing extremities; a latch bolt mounted on the frame at a first one of said two extremities and being moveable between a latching position and a retracted position, the latch bolt comprising a second magnetic element; a latch bolt biasing member arranged to urge the latch bolt into its retracted position, wherein the first magnetic element and the second magnetic element are configured to magnetically attract each other to move the latch bolt into its latching position against the latch bolt biasing member; and a latch bolt operating mechanism including an actuator mounted on the frame at a second one of said two extremities, the latch bolt operating mechanism being configured to, upon actuation of the actuator, move the latch bolt from its latching position to its retracted position against the magnetic attraction between said first and said second magnetic element, wherein the latch bolt operating mechanism comprises: an effort link rod extending in the vertical direction and coupled to the actuator and moveable by a translational motion along the vertical direction from a rest position to an actuated position upon actuation of the actuator; a load link rod extending in the vertical direction and coupled to the latch bolt and moveable by a translational motion along the vertical direction from a rest position to an actuated position upon actuation of the actuator; and a second-order lever interposed between the effort link rod and the load link rod and rotatable about a fulcrum mounted on the frame between a rest position and an actuated position, wherein the second-order lever has a fulcrum with the load link rod being closer to the fulcrum than the effort link rod.

2. The magnetic latch according to claim 1, wherein the second-order lever is rotatable in a plane between its rest position and its actuated position, the plane having a component in the vertical direction and in a horizontal direction, the second-order lever being slideable in the horizontal direction with respect to effort link rod and/or the load link rod and/or the frame.

3. The magnetic latch according to claim 2, wherein the second-order lever comprises a fulcrum opening, an effort opening, and a load opening, the fulcrum being disposed in the fulcrum opening, the effort link rod being connected to the second-order lever by a transverse pin disposed in the effort opening and the load link rod being connected to the second-order lever by a transverse pin disposed in the load opening.

4. The magnetic latch according to claim 3, wherein at least two of the fulcrum opening, the effort opening, and the load opening are elongated in the horizontal direction.

5. The magnetic latch according to claim 1, wherein the second-order lever comprises a fulcrum opening, an effort opening, and a load opening, the fulcrum being disposed in the fulcrum opening, the effort link rod being connected to the second-order lever by a transverse pin disposed in the effort opening and the load link rod being connected to the second-order lever by a transverse pin disposed in the load opening.

6. The magnetic latch according to claim 1, wherein the latch bolt operating mechanism further comprises a slideable coupler disposed between the load link rod and the latch bolt and moveable, by a translational motion along the vertical direction, between a releasing position in which the load link rod does not engage the slideable coupler and an engaging position in which the load link rod engages the slideable coupler, and in that the releasing position of the slideable coupler corresponds to the retracted position of the latch bolt and the engaging position of the slideable coupler corresponding to the extended position of the latch bolt.

7. The magnetic latch according to claim 6, characterized in that the load link rod has a widened lower end and in that slideable coupler comprises a vertically oriented groove in which the widened lower end is positioned and an assembly opening adjacent the vertically oriented groove, wherein the load link rod is connected to the slideable coupler by placing the widened lower end in the assembly opening and afterwards rotating the load link rod to allow the widened lower end to be slid into the vertically oriented groove.

8. The magnetic latch according to claim 1, wherein the actuator is directly connected to the effort link rod.

9. The magnetic latch according to claim 6, characterized in that the actuator is connected to the effort link rod by an angular snap-fit joint, the actuator preferably comprising an internal chamber into which a locally widened end of the effort link rod is positioned.

10. The magnetic latch according to claim 1, wherein the latch bolt is moveable in the vertical direction between its latching position and its retracted position by a translational motion along the vertical direction.

11. The magnetic latch according to claim 10, wherein the latch bolt operating mechanism further comprises a slideable coupler disposed between the load link rod and the latch bolt and moveable, by a translational motion along the vertical direction, between a releasing position in which the load link rod does not engage the slideable coupler and an engaging position in which the load link rod engages the slideable coupler, and in that the releasing position of the slideable coupler corresponds to the retracted position of the latch bolt and the engaging position of the slideable coupler corresponding to the extended position of the latch bolt, that latch bolt being fixedly connected to the slideable coupler.

12. The magnetic latch according to claim 11, wherein the latch bolt comprises a circumferential groove, the latch bolt being connected to the slideably coupler by a pin which is partially positioned within the circumferential groove.

13. The magnetic latch according to claim 11, wherein the latch bolt biasing member comprises a compression spring having a first end engaging the slideable coupler and a second end engaging the frame.

14. A magnetic latch for fastening a closure member to a support, the magnetic latch comprising a latch bolt assembly configured to be mounted to one of the closure member and the support and a keeper assembly configured to be mounted to the other one of the closure member and the support, the latch bolt assembly comprising: a latch bolt moveable between a latching position and a retracted position, the latch bolt comprising a first magnetic element; and a latch bolt biasing member arranged to urge the latch bolt into its retracted position, the keeper assembly comprising: an elongated frame extending in a vertical direction and having two opposing extremities; a second magnetic element mounted on the frame at a first one of said two extremities and being moveable between a rest position in which the first magnetic element and the second magnetic element magnetically attract each other to move the latch bolt into its latching position against the latch bolt biasing member and an actuated position; and an operating mechanism including an actuator mounted on the frame at a second one of said two extremities, the operating mechanism being configured to, upon actuation of the actuator, move the second magnetic element from its rest position to its actuated position, wherein the operating mechanism comprises: an effort link rod extending in the vertical direction and coupled to the actuator and moveable by a translational motion along the vertical direction from a rest position to an actuated position upon actuation of the actuator; a load link rod extending in the vertical direction and coupled to the second magnetic element and moveable by a translational motion along the vertical direction from a rest position to an actuated position upon actuation of the actuator; and a second-order lever interposed between the effort and the load link rod and rotatable about a fulcrum mounted on the frame between a rest position and an actuated position, wherein the second-order lever has a fulcrum with the load link rod being closer to the fulcrum than the effort link rod.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention will be further explained by means of the following description and the appended figures.

[0056] FIG. 1 shows a perspective view of an embodiment of a magnetic latch assembly mounted on a closure system.

[0057] FIG. 2 shows a perspective view of the latch bolt assembly and the magnetic keeper assembly that form the magnetic latch assembly of FIG. 1.

[0058] FIG. 3A shows a front view of the latch bolt assembly of FIG. 2 with the housing having been removed and with the latch bolt in its latched state.

[0059] FIG. 3B shows a cross-section through the latch bolt assembly along plane ‘A’ indicated in FIG. 3A.

[0060] FIG. 4A shows a front view of the latch bolt assembly of FIG. 2 with the housing having been removed and with the latch bolt in its retracted state and the knob in its actuated position.

[0061] FIG. 4B shows a cross-section through the latch bolt assembly along plane ‘A’ indicated in FIG. 4A.

[0062] FIG. 5A shows a front view of the latch bolt assembly of FIG. 2 with the housing having been removed and with the latch bolt in its retracted state and the knob in its rest position.

[0063] FIG. 5B shows a cross-section through the latch bolt assembly along plane ‘A’ indicated in FIG. 5A.

[0064] FIG. 6 shows a perspective, partially exploded, view of the top part of the latch bolt assembly of FIG. 2 with the housing having been removed and with the knob in its rest position.

[0065] FIG. 7A shows a perspective view of the top part of the latch bolt assembly of FIG. 2 with the housing having been removed, with the locking mechanism in its unlocking position and with the knob in its rest position.

[0066] FIG. 7B shows a similar view as FIG. 7A but with the locking mechanism in its locking position and with the knob between its actuated and its rest position.

[0067] FIG. 7C shows a similar view as FIG. 7B but with the locking mechanism in its locking position and with the knob in its rest position.

[0068] FIGS. 8A to 8C show the same configuration as FIGS. 7A to 7C with a front view.

[0069] FIG. 9A shows an exploded view of the magnetic keeper assembly of FIG. 2.

[0070] FIG. 9B shows a top view of the magnetic keeper assembly of FIG. 2.

[0071] FIG. 9C shows a rear side view of the magnetic keeper assembly of FIG. 2.

[0072] FIG. 10 shows a front view of the pawl locking member.

DESCRIPTION OF THE INVENTION

[0073] 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. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not necessarily correspond to actual reductions to practice of the invention.

[0074] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated herein.

[0075] Moreover, the various embodiments, although referred to as “preferred” are to be construed as exemplary manners in which the invention may be implemented rather than as limiting the scope of the invention.

[0076] FIG. 1 shows a perspective view of a first embodiment of a magnetic latch assembly 1 mounted on a closure system. The closure system comprises a closure member 2 that is hinged on a first support 3 and that may be fastened to a second support 4 by means of the magnetic latch assembly 1. In the illustrated embodiment, the closure member 2 is formed by a gate and the supports 3, 4 are formed by fixed posts, but it will be readily appreciated that the magnetic latch assembly 1 is also suitable for other kinds of closure members (e.g. a sliding closure member, a door, etc.) and/or supports. For example, the support may be formed by a closure member in case the magnetic latch assembly 1 is used on a double gate.

[0077] The magnetic latch assembly 1 generally comprises a latch bolt assembly 5 and a magnetic keeper assembly 6 as shown in FIG. 2. In the illustrated embodiment, the latch bolt assembly 5 is mounted on the support 4 and the magnetic keeper assembly 6 is mounted on the closure member 2, but it will be readily appreciated that these may be reversed. As shown in FIG. 2, the latch bolt assembly 5 comprises a vertically oriented elongated housing 7 with a pull knob 8 protruding from the top thereof. The housing 7 is mounted on the closure member 2 using two L-shaped mounting brackets 9. Preferably, the height of the housing 7 with respect to the mounting brackets 9 is adjustable in order to vertically align the latch bolt assembly 5 mounted on the support 4 to the magnetic keeper assembly 6 mounted on the closure member 2. At the bottom of the housing 7, there is provided an L-shaped bracket 10 having one leg 11 fastened to the bottom of the housing using screws 12 (see FIG. 3A) and a second leg 13 which is located opposite the magnetic keeper assembly 6 and to which the bottom L-shaped mounting bracket 9 is fastened. The L-shaped bracket 10 is open at both sides in order to engage with the magnetic keeper assembly 6 on either side such that the latch bolt assembly 5 is operable for both right-handed and left-handed closure members 2 without any modifications. It will be readily appreciated that the elongated housing 7 may be regarded as a frame on which the various components of the latch bolt assembly are mounted. The operation of the latch bolt assembly 5 will be described in more detail by reference to FIGS. 3A to 8C. The magnetic keeper assembly 6 will be described in more detail by reference to FIGS. 9A to 9C.

[0078] FIGS. 3A and 3B show the latch bolt assembly 5 in its latched position, i.e. where the closure member 2 is fastened to the support 4. The latch bolt assembly 5 comprises a latch bolt 14 at its bottom. More specifically, the latch bolt 14 extends through the first leg 11 of the L-shaped bracket 10 and is moveable in the vertical direction 15 between an extended position (shown in FIGS. 3A and 3B) and a retracted position (shown in FIGS. 4A to 5B). The latch bolt 14, at its upper end 14a, is fixedly connected to a slideable coupler 15, in particular to the lower end 15a thereof, in particular by a transversely positioned pin 16. More specifically, the latch bolt 14 is provided with a circumferential groove (best shown in FIG. 3A) and the transversely positioned pin 16 (e.g. a rivet) partially engages part of this circumferential groove. A latch bolt spring 17 is positioned between the coupler 15 and the top side of the L-shaped bracket 10. In the illustrated embodiment, the latch bolt spring 17 is a compression spring which urges the upper end of the latch bolt 14 upwards, i.e. away from the top side of the L-shaped bracket 10. As such, the latch bolt 14 is urged by the latch bolt spring 17 towards the retracted position.

[0079] The magnetic keeper assembly 6 is shown in an exploded view in FIG. 9A and comprises a keep 18 which houses a magnet 19, in particular a permanent magnet, although it will be readily appreciated that an electromagnet is also feasible. The keep 18 has an elongated part 20 on its side in order to allow the keep 18 to be mounted on the closure member 2 by means of an L-shaped mounting bracket 21. More specifically, the L-shaped mounting bracket 21 is mounted to the closure member 2 and a horizontal guide 22 is mounted directly on the L-shaped mounting bracket 21 (and fixed thereto by means of screw 30) with the elongated part 20 of the keep 18 being mounted on the horizontal guide 22. A setting screw 23 and corresponding setting nut 24 are provided in order to horizontally adjust the position between the keep 18 and the horizontal guide 22. More specifically, the setting nut 24 is positioned on one side within a corresponding hole 27 on the horizontal guide and with the other side in a horizontal groove 28 in the elongated part 20. The setting nut 24 is provided with an internal screw thread corresponding to that of the setting screw 23. A rotation of the setting screw 23 causes the setting nut 24 to slide along the length of the setting screw 23 (as best shown in FIG. 9C) thus causing the keep 18 to slide horizontally with respect to the horizontal guide 22 that is fixedly positioned on the closure member 2. This allows to correctly position the keep 18, in particular the latch bolt receiving area 29, with respect to the latch bolt assembly 5 mounted on the support 4. A curved washer 25 may be provided between the setting screw 23 and the setting nut 24. A cover 26 is provided in order to finish the magnetic keeper assembly 6.

[0080] When the closure member 2 is closed (as illustrated in FIG. 1), the magnet 19 provided in the magnetic keeper assembly 6 exerts a force on the latch bolt 14 thereby attracting the latch bolt 14 against the force of the latch bolt spring 17 to its latching position. As such, the latch bolt 14 is manufactured from a ferromagnetic material, preferably iron. When the latch bolt 14 is in its latching position, it, in particular its lower end 14b, is kept by the keep 18, in particular in the latch bolt receiving area 29, the magnetic keeper assembly 6 in order to fasten the closure member 2 to the support 4. More specifically, when the latch bolt 14 is in its latched position in the keeper 18, the bottom part of the latch bolt 14, when attempting to open the closure member 2, pushes against the bounding wall 31 of the latch bolt receiving area 29.

[0081] The latch bolt assembly 5 is generally provided with a latch bolt operating mechanism which allows to retract the latch bolt 14 against the force of the magnet 19 in order to unfasten the closure member 2 with respect to the support 4. In the illustrated embodiment, the latch bolt operating mechanism comprises a frame 32 that is fixed to the housing 7, the knob 8 at the top of the housing 7, an upper link rod 33 connected to a lower link rod 34 by a lever 35.

[0082] The upper link rod 33 comprises a top part 36 and a bottom part 37 connected by a horizontal plate 39 such that these parts 36, 37 are located in a different position when viewed in the depth direction 38 (see FIG. 3B) of the latch bolt assembly 5. The reasons as to why the upper link rod 33 is so split will be described below with reference to FIGS. 6 to 8C. The top part 36 of the upper link rod 33 has an upper end 36a on which the knob 8 is fixed and a lower end 36b that is fixed on the horizontal plate 39. The bottom part 37 of the upper link rod 33 has an upper end 37a that is fixed on the horizontal plate 39 and a lower end 37b that is connected to the lever 35.

[0083] In the illustrated embodiment, the knob 8 is fixed to the upper end 36a of the upper link rod 33 by an angular snap-fit joint. The angular snap-fit joint is best shown in FIG. 3B. The angular snap-fit joint comprises a chamber within the knob 8, which chamber has a larger cross-section at the top and a smaller cross-section at the bottom. The upper end 36a of the upper link rod 33 has a corresponding locally thicker part. When assembling the latch bolt assembly 5, the knob 8 is slid onto the upper link rod 33 of which the thicker top part is compressed and the re-expands to fill the chamber. This provides a robust connection which is moreover invisible from the outside of the magnetic latch 1. In the illustrated embodiment, the knob 8 is made from metal, while the upper link rod 33 is made from a plastic material.

[0084] The lever 35 has a first end 35a, a central part 35b, and a second end 35c. The lower end 37b of the bottom part 37 of the upper link rod 33 is connected to the first end 35a of the lever 35 by means of a pin 40 transversely placed extending through openings (not shown) in the lower end 37b of the bottom part 37 of the upper link rod 33 and the first end 35a of the lever 35. The frame 32 has a vertically oriented protrusion 41 which has a upper end 41a fixed to the frame 32 and a lower end 41b which is connected to the second end 35c of the lever 35 by means of a pin 42 transversely placed extending through an opening (not shown) in the lower end 41b of the protrusion 41 and through an elongated opening 43 in the second end 35c of the lever 35. The central part 35b of the lever 35 also has an elongated opening 44 used for connecting the upper end 34a of the lower link rod 34 to the lever 35 by means of a pin 45 transversely placed extending through an opening (not shown) in the upper end 34a of the lower link rod 34 and through the elongated opening 44.

[0085] The lever 35 is rotatable about its second end 35c between a rest position (shown in FIGS. 3A, 3B, 5A and 5B) and an actuated position (shown in FIGS. 4A and 4B). More specifically, the first end 35a of the lever 35 is able to rotate, in particular over an angle of about 90°, with respect to the transverse pin 42 around the width direction 46 (indicated in FIG. 3A). The elongated openings 43, 44 allow the upper link bar 33 and the lower link bar 34 to remain vertically oriented during the rotation of the lever 35 as the lever 35 can slide in the depth direction 38 with respect to the lower end 37b of the upper link bar 33 and the upper end 34a of the lower link bar 34, which sliding motion would not be possible in case the openings 43, 44 were circular.

[0086] The lower link rod 34 has a lower end 34b that engages the slideable coupler 15. More specifically, the upper end 15b of the coupler 15 has an opening (not shown) through which the lower link rod 34 extends. The lower end 34b of the lower link rod 34 is so shaped that it cannot pass through the opening in the upper end 15b of the coupler 15 as best in FIG. 3B. The coupler 15 has a vertically oriented groove 47 and the lower end 34b is guided in this groove 47. The coupler 15 is slideable between a lower position (shown in FIGS. 3A and 3B) and an upper position (shows in FIGS. 4A to 5B). The lower position of the coupler 15 corresponds to the latched position of the latch bolt 14 and the upper position of the coupler 15 corresponds to the retracted position of the latch bolt 14 because the upper end 14a of the latch bolt 14 is fixed to the lower end 15a of the coupler 15 as described above. The coupler 15 further has an opening 48 adjacent the groove 47, which opening 48 allows to place the coupler 15 on the lower end 34b of the lower link rod 34.

[0087] The latch bolt assembly 5 operates in the following way. FIGS. 3A and 3B show the latch bolt 14 in its latching position due to the magnetic attraction from the magnet 19 in the magnetic keep assembly 6. When a user desires to open the closure member 2, the user pulls the knob 8 upwards from its rest position to its actuated position as shown in FIGS. 4A and 4B. The upwards movement of the knob 8 causes the upper link rod 33 to move upwards (i.e. the upper link rod 33 undergoes an upwards translational motion) thereby rotating the first end 35a of the lever 35 in a first rotational direction 49 and pulling the lower link rod 34 upwards (i.e. the lower link rod 34 undergoes an upwards translational motion). Because the lower end 34b of the lower link rod 34 is abutting the upper end 15b of the coupler 15, the coupler 15 is pulled upwards which in turn pulls latch bolt 14 upwards to its retracted position (i.e. the latch bolt 14 and the coupler 15 undergo an upwards translational motion). Once the latch bolt 14 is in its retracted position, the closure member 2 is unfasted and the user may open the closure member 2 and the knob 8 may be let go. Gravity will cause the knob 8 to fall downwards to its rest position as shown in FIGS. 5A and 5B. The downwards movement of the knob 8 causes the upper link rod 33 to move downwards (i.e. the upper link rod 33 undergoes a downwards translational motion) thereby rotating the first end 35a of the lever 35 in a second rotational direction 50 (which is opposite to the first rotational direction 49) and pushing the lower link rod 34 downwards (i.e. the lower link rod 34 undergoes a downwards translational motion). Since the lower end 34b of the lower link rod 34 is free to slide within the groove 47 in the coupler 15, the coupler 15 is not affected by the motion of the lower link rod 34. Rather, the coupler 15 remains in its upper position due to the latch bolt spring 17 thus keeping the latch bolt 14 in its retracted state. When the closure member 2 is again closed (either due to the user or due to the provision of self-closing means, e.g. a self-closing hinge), the magnet 19 again attracts the latch bolt 14 thus pulling the latch bolt 14 and the coupler 15 downwards (i.e. the latch bolt 14 and the coupler 15 undergo a downwards translational motion) against the latch bolt spring 17 to the configuration shown in FIGS. 3A and 3B.

[0088] The force required to unfasten the closure member 2 is effectively determined by the magnetic field strength H of the magnet 19, the shape of the latch bolt 14 and the configuration of the lever 35. Increasing the magnetic field strength H increases the force exerted on the latch bolt 14. A likewise effect may be achieved by increasing the volume of the latch bolt 14 as this also increases the magnet force exerted thereon. However, this results in a bulkier latch bolt assembly 5 which is undesired. A higher attraction force is beneficial as this allows to attract the latch bolt 14 from greater distances thus allowing more leeway between the support 4 and the closure member 2. However, a downside of a higher attraction force is that the user has to exert a higher force on the knob 8 in order to retract the latch bolt 14. The lever 35 alleviates this effect since it causes a force reduction between the lower link rod 34 and the upper link rod 33. In other words, the lever 35 is a second-order lever with the upper link 33 being the effort and the lower link 34 being the load and the transverse pin 42 forming the fulcrum.

[0089] In the illustrated embodiment, the magnet 19 is a neodymium magnet with 22 kg of retaining force and a height and diameter of 25 mm. The magnet 19 exerts an attraction force on the latch bolt 14 (which latch bolt 14 has a diameter of 12 mm in the illustrated embodiment, but other diameters are possible) between 65 and 70 N and the lever 35 reduces the force such that the knob 8 can be lifted by applying a pulling force between 30 and 40 N. However, other force values are also possible. In general, the force required to pull the knob 8 is between 15 and 60 N, preferably between 20 and 50 N, and more preferably between 25 and 45 N. The magnetic attraction force exerted on the latch bolt 14 is preferably as large as possible and may generally be between 40 and 150 N, preferably between 50 and 100 N and more preferably between 60 and 90 N. This allows to attract the latch bolt 14 from distances exceeding 10 mm thus allowing more leeway between the support 4 and the closure member 2.

[0090] The latch bolt assembly 5 is also provided with a key cylinder 51 that allows to lock the closure member 2 in its fastened position with respect to the support 4. In other words, the key cylinder 51 is part of a locking mechanism that prohibits movement operation of the latch bolt operating mechanism. The locking mechanism will be described with respect to FIGS. 6 to 8C. The key cylinder 51 is a Euro-cylinder corresponding to standard DIN 18252/2006 (as shown in FIGS. 3B, 4B and 5B) which may be operated from either side of the closure member 2 and has a single rotary driving bit 52 centrally positioned with respect to the key cylinder 52. However, other kinds of key cylinder 51 (e.g. a key-in-knob cylinder) are known to the skilled person and may also be used in the latch bolt assembly.

[0091] The key cylinder 51 is fixed to the frame 32 by a transversely positioned bolt 103 shown in FIGS. 8A to 8C. The key cylinder 51 is placed centrally with respect to the housing 7 of the latch bolt assembly 5. This central placement is possible due to the specific shape of the upper link rod 33. More specifically, the bottom part 37 of the upper link rod 33 has two parallel legs 37c, 37d with a groove 53 provided therebetween. The key cylinder 51 extends through this groove 53 and the groove 53 is substantially elongated to allow the bottom part 37 of the upper link rod 33 to slide with respect to the frame 32 as required for the normal operation of the latch bolt operating mechanism described above. Furthermore, the bottom part 37 of the upper link rod 33 is positioned more closely to the frame 32 with respect to the top part 36 of the upper link rod 33. This provides the required space for the rotary driving bit 52 of the key cylinder 51 which may freely rotate adjacent to the bottom part 37 of the upper link rod 33. An alternative would be to make the groove 37 wider to allow a rotation of the rotary driving bit 52. In this way, the top part 36 and the bottom part 37 of the upper link rod 33 may be placed in the same plane, however this increases the width of the latch bolt assembly 5, meaning that the latch bolt assembly 5 is quite bulky and has to be wider than the support 4 which is undesired.

[0092] The locking mechanism comprises a pawl locking member 54 that is mounted on the frame 32 by a transverse pin 55 that is placed through an opening 56 in the frame 32, an opening 57 in the pawl locking member 54 and into a hole (not shown) provided in the frame 32. The pin 55 forms a pivot around which the pawl locking member 54 is rotatable between a first position (shown in FIGS. 7A and 8A) and a second position (shown in FIGS. 7B, 7C, 8B and 8C). The pawl locking member 54 is guided between its two positions by means of a curved slot 66 and a cooperating pin 67 (shown in FIG. 8B). The pin 67 is fixed to the frame 32 and movement of the pawl locking member 54 beyond its two positions is prevented as the pin 67 engages the ends of the slot 66. The bottom part of the pawl locking member 54 has a groove 58 formed by two sidewalls 58a, 58b in a shape corresponding to that of the rotary driving bit 52.

[0093] The shape of the slot 66 is best illustrated in FIG. 10 which shows a front view of the pawl locking member 54. The groove 66 has a specific shape with a narrower central part 113 and larger (compared to the central part 113) end regions 111, 112. The narrower central part 113 is caused by inwardly positioned ridges 114, 115. Besides these ridges 114, 115, there is provided a groove or opening 116, 117 in the pawl locking member 54. More generally, the groove or opening 116, 117 may be formed by a local weakening of the pawl locking member 54 in order to allow the ridges 114, 115 to be displaced outwards due to the pin 67 moving between the end regions 111, 112 upon actuation of the key cylinder 51. The ridges 114, 115 are resilient and urge the pin 67 to either one of the end regions 111, 112. As such, the specific shape forms a bi-stable pawl locking member 54.

[0094] The locking mechanism further comprises a pawl 59 that is mounted on the pawl locking member 54. More specifically, the pawl 59 has an opening 60 with the pin 55 also being placed through this opening 60 to mount the pawl 59 to the pawl locking member 54 and the frame 32. The pin 55 thus also forms a pivot around which the pawl 59 is able to rotate between a rest position with respect to the pawl locking member 54 (shown in FIGS. 7A, 7C, 8A and 8C) and a displaced position with respect to the pawl locking member 54 (shown in FIGS. 7B and 8B). The pawl locking member 54 is provided with an abutment 62 which defines the rest position of the pawl 59, i.e. in the rest position the pawl 59 abuts against the abutment 62 provided on the pawl locking member 54. A spring 61 is disposed between the pawl locking member 54 and the pawl 59 in order to urge the pawl 59 into its rest position with respect to the pawl locking member 54, i.e. pushing the pawl 59 against the abutment 62. The spring 61 is a torsion spring having a first end 61a that engages the pawl locking member 54 and a second end 61b that engages the pawl 59. The pawl 59 further comprises an abutment surface 63 against which the top surface 64 of the horizontal plate 39 (which is part of the upper link rod 33) may abut.

[0095] The locking mechanism operates in the following way. When the key cylinder 51 is unlocked (as shown in FIGS. 7A and 8A), the pawl 59 is in its rest position with respect to the pawl locking member 54 which itself is located in its first position. The abutment surface 63 of the pawl 59 is positioned next to the top surface 64 of the horizontal plate 39 which is part of the upper link rod 33. As such, the pawl 59 is in its retracted position and normal operation (i.e. an upwards translation upon pulling the knob 8) of the upper link member 33 is possible as shown in FIGS. 7A and 8A. For this reason, the first position of the pawl locking member 54 is also referred to as the locking position since the pawl 59 is locked in its retracted position with respect to the upper link member 33 and normal operation is allowed. Actuating the key cylinder 51 causes a rotation of the rotary driving bit 52 in a locking direction 65 (indicated in FIG. 8A) and causes the pawl locking member 54 to be rotated towards its second position. The pawl 59 remains stationary with respect to the pawl locking member 54 and thus remains in its rest position. The abutment surface 63 of the pawl 59 is positioned above the top surface 64 of the horizontal plate 39 which is part of the upper link rod 33. As such, the pawl 59 is in its extended position and normal operation (i.e. an upwards translation upon pulling the knob 8) of the upper link member 33 is prevented as shown in FIGS. 7C and 8C. Actuating the key cylinder 51 causes a rotation of the rotary driving bit 52 in a unlocking direction 68 (indicated in FIG. 8C) and causes the pawl locking member 54 to be rotated towards its first position shown in FIG. 8A thereby again allowing normal operation.

[0096] The main advantage of the pawl 59 and the pawl locking member 54 is to avoid blocking the knob 8 in the actuated (i.e. upwards) position when the key cylinder 51 is actuated while the knob 8 is kept upwards by the user as illustrated in FIGS. 7B and 8B. More specifically, in case the knob 8 is pulled upwards (i.e. the upper link rod 33 is in an upwards position) and the key cylinder 51 is actuated to move the pawl locking member 54 to its second position, a pawl that is fixed on the pawl locking member 54 would prevent the knob 8 being pulled downwards by gravity to its rest position. However, as the pawl 59 is rotatable with respect to the pawl locking member 54, the downwards motion of the knob 8 and the upper link rod 33 (i.e. the horizontal plate 39) pushes the pawl 59 (in particular against the side surface 102 of the pawl 59) to the side (i.e. against the spring 61). Once the horizontal plate 39 has passed the pawl 59, the spring 61 pushes the pawl 59 against the abutment surface 62 on the pawl locking member 54 to its locking position illustrated in FIGS. 7C and 8C. For this reason, the second position of the pawl locking member 54 is also referred to as the release position since the pawl 59 is released and is free to be moved from its extended to its retracted position by the downwards motion of the knob 8.

[0097] It will be appreciated that variations of the construction of the pawl 59 and/or the pawl locking member 54 are possible. For example, the spring 61 may be interposed between the pawl 59 and the frame 62, the pawl 59 and/or the pawl locking member 54 may undergo a translational motion instead of a rotary motion, the pawl 59 and the pawl locking member 54 may be mounted on different rotational axes, the pawl 59 may engage another part of the upper link rod 33, etc.

[0098] It will be readily appreciated that various modifications are possible in which the advantages of the second-order lever between the link rods 33, 34 and/or of the locking mechanism are also obtained. For example, in an embodiment, the magnetic roles of the latch bolt 14 and the magnet 19 are reversed. In other words, the latch bolt 14 is a permanent magnet and element 19 is made from a ferromagnetic material (e.g. iron). The operation of the magnetic latch assembly 1 remains unaffected because the latch bolt 14 will still be attracted to the element 19 as this is fixedly positioned within the keeper assembly 6. Moreover, it is also possible that the latch bolt 14 and the magnet 19 are permanent magnets and/or electromagnets. In another embodiment, the latch bolt 14, coupler 15 and latch bolt spring 17 are replaced by a magnetic element fixed to the lower end 34a of the lower link rod 34. The keeper assembly 6 is replaced by a latch bolt assembly having a horizontally oriented latch bolt that is biased towards its retracted position and is attracted by the magnetic element fixed to the lower end 34a. Such embodiments are disclosed in AU 2009/251007 A1, AU 2013/206766 A1, 2014/203446 A1, AU 2016/201778 A1, and AU 2018/256525 A1. Furthermore, it is also possible to reverse the roles of the magnet and the latch bolt in such an embodiment, i.e. have the horizontal latch bolt form the permanent magnet and have a ferromagnetic material fixed to the lower end 34a of the lower link rod 34. Moreover, the position of the latch bolt assembly 5 and the keeper assembly 6 may also be reversed, i.e. the latch bolt assembly 5 may be mounted on the closure member 2 and the keeper assembly 6 on the support 4.

[0099] Although aspects of the present disclosure have been described with respect to specific embodiments, it will be readily appreciated that these aspects may be implemented in other forms within the scope of the invention as defined by the claims.