Patent Application
20130127184
The present invention relates to a latch assembly for a passageway door lock and, more particularly, to a latch assembly for a door lock mounted in a passageway or panic exit, with the latch assembly including a latch that can be reliably retained in an unlatching position.
Locks mounted to doors in passageways or panic exits generally include horizontal type latches and vertical type latches. Vertical type latches include a top latch and a bottom latch. The latch bolts of the top and bottom latches should be retained by corresponding strikes in extended, latching positions when the door is closed and should be in retracted, unlatching positions when the door is being opened. The top and bottom latches generally move jointly such that one can not move without moving the other. However, in a case that the latch bolt of the top latch is moved to the unlatching position, due to the plays of the parts of the bottom latch after assembly, the latch bolt of the bottom latch could be further moved towards the latching position to a location interfering with the ground. As a result, the door can not be smoothly opened even though the latch bolt of the bottom latch is not in the latching position.
Thus, a need exists for a latch assembly for a passageway door lock in which the latch assembly can be reliably retained in the unlatching position to avoid interference to opening of the door.
The present invention solves this need and other problems in the field of smooth opening of passageway doors by providing a latch assembly including a base having first and second sidewalls and a main section extending between the first and second sidewalls. Each of the first and second sidewalls of the base includes a first sliding groove, a first guiding groove, and a second guiding groove. The first guiding groove of each of the first and second sidewalls of the base includes a vertical section and an inclined section. The main section is adapted to be mounted to a door. A latch is movably received between the first and second sidewalls of the base. The latch has a first pivotal portion pivotably connected to the first and second sidewalls of the base and a second pivotal portion. The latch is movable between a latching position outside the base and an unlatching position inside the base. A link includes a first end pivotably connected to the second pivotal portion of the latch. A second end of the link is slideably engaged with the first and second sidewalls of the base. Movement of the link along a first axis causes movement of the latch between the latching position and the unlatching position.
The latch assembly further includes a follower plate movable along the first axis. The follower plate includes first and second sidewalls spaced along a second axis perpendicular to the first axis and an intermediate portion extending between the first and second sidewalls of the follower plate. Each of the first and second sidewalls of the follower plate includes first and second ends. The first and second sidewalls of the follower plate are movably received between the first and second sidewalls of the base. A restraining slot is formed in each of the first and second sidewalls of the follower plate and located between the first and second ends of the first and second sidewalls of the follower plate. The restraining slot of each of the first and second sidewalls of the follower plate includes upper and lower edges spaced along the first axis and parallel, spaced, first and second lateral edges extending between the upper and lower edges. The upper edge has an upper end connected to an upper end of the first lateral edge. The upper edge has a lower end connected to an upper end of the second lateral edge. The first and second lateral edges are substantially parallel to the vertical sections of the first guiding slots of the base. A first corner is formed between a lower end of the second lateral edge and an end of the lower edge. A second corner is formed between the upper end of the upper edge and the upper end of the first lateral edge. A third corner is formed between a lower end of the first lateral edge and the other end of the lower edge. Each of the first and second sidewalls of the follower plate further includes an engaging notch and a slot. The restraining slot is located between the engaging notch and the intermediate portion of the follower plate along a third axis perpendicular to the first and second axes. The slot extends in a direction parallel to the first and second lateral edges. The first ends of the first and second sidewalls of the follower plate are pivotably connected to the second end of the link. The first corners of the restraining slots of the follower plate are aligned with the inclined sections of the first guiding slots of the base when the latch is in the latching position. When the latch is in the unlatching position, the second corners of the restraining slots of the follower plate are aligned with distal ends of the vertical sections of the first guiding slots of the base, and the engaging notches of the follower plate are aligned with the second guiding slots of the base.
The latch assembly further includes a linking rod having a first end slideably coupled with the slots of the first and second sidewalls of the follower plate. The linking rod further includes a second end adapted to be connected to a door lock mounted to the door to move therewith. A safety plate is mounted between the first and second sidewalls of the follower plate. The safety plate includes two sidewalls spaced along the second axis. Each of the two sidewalls of the safety plate includes first and second ends. The second end of the two sidewalls of the safety plate pivotably connected to the first end of the linking rod. Each of the two sidewalls of the safety plate further includes an engaging notch and a hole. A pin extends through the first guiding slots of the base, the restraining slots of the follower plate, and the holes of the safety plate. The safety plate is pivotable relative to the follower plate about a pivot axis defined by the pin. A positioning pin extends through the second guiding slots of the base. A spring is attached between the positioning pin and the pin to bias the positioning pin and the pin towards each other.
When the latch is in the latching position, the engaging notches of the safety plate are engaged with the positioning pin. The pin is located in distal ends of the inclined sections of the first guiding slots of the base and in the first corners of the restraining slots of the follower plate. The positioning plate is stopped by the positioning pin when the latch is picked, preventing the latch from moving from the latching position to the unlatching position by avoiding the follower plate from moving along the first axis.
When the linking rod moves along the first axis away from the latch through a travel substantially equal to a length of each of the slots of the follower plate while the latch is in the latching position, the engaging notches of the safety plate disengage from the positioning pin. The pin moves to an intersection of the vertical section and the inclined slot of each of the first guiding slots of the base and abuts the first lateral edge of each of the restraining slots of the follower plate.
When the latch is in the latching position and when the linking rod moves along the first axis away from the latch through a travel larger than the length of each of the slots of the follower plate, the latch moves from the latching position to the unlatching position. The positioning pin moves along the second guiding slots of the base under action of the spring and engages with the engaging notches of the follower plate to retain the latch in the unlatching position. The pin is located in the distal ends of the vertical sections of the first guiding slots of the base and in the second corners of the restraining slots of the follower plate.
When the latch in the unlatching position and when the lining rod moves along the first axis towards the latch through a travel slightly smaller than the length of each of the slots of the follower plate, the first ends of the two sidewalls of the safety plate press against the positioning pin to move the positioning pin along the second guiding slots of the base, disengaging the positioning pin from the engaging notches of the follower plate and releasing the follower plate, and the latch moves from the unlatching position to the latching position under action of another spring.
The present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.
The illustrative embodiment may best be described by reference to the accompanying drawings where:
All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the Figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.
Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “lower”, “upper”, “top”, “bottom”, “inner”, “outer”, “end”, “portion”, “section”, “longitudinal”, “vertical”, “length”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.
In the form shown, bottom latch 25 is comprised of basic parts of top latch 24. According to the form shown, bottom latch 25 includes a base 3, a latch bolt 4, a follower plate 5A, a linking rod 6, and a locking device 7. Base 3 is substantially U-shaped and includes first and second sidewalls 32 and a main section 31 extending between first and second sidewalls 32. Main section 31 includes first and second ends 37 and 38 spaced along a first axis X. Main section 31 includes first and second holes 311 and 312 spaced along first axis X. A protrusion 314 is formed between first and second holes 311 and 312. First and second sidewalls 32 are spaced along a second axis Y perpendicular to first axis X and each include first and second ends 33 and 34 spaced along first axis X. First and second sidewalls 32 include aligned first sliding slots 321 adjacent first ends 33 and aligned second sliding slots 322 adjacent second ends 34. Each of first and second sliding slots 321 and 322 has a length extending along first axis X. First and second sidewalls 32 further include aligned first guiding slots 323 and aligned second guiding slots 324. First guiding slot 323 on each of first and second sidewalls 32 is located between first sliding slot 321 and second sliding slot 322 along first axis X. Furthermore, first guiding slot 323 includes a vertical section 327 extending in a direction parallel to first sliding slot 321 and an inclined section 328 at an obtuse angle (about 130° in the form shown) to vertical section 327. Second guiding slot 324 on each of first and second sidewalls 32 is located between first guiding slot 323 and first sliding slot 321 along first axis X. Second guiding slot 324 has a length extending along a third axis X perpendicular to first and second axes X and Y (i.e., perpendicular to first sliding slot 321). First and second sidewalls 32 further include aligned pin holes 329 at first ends 33 thereof. First and second sidewalls 32 further include aligned positioning holes 325. Positioning hole 325 on each of first and second sidewalls 32 is spaced from first guiding slot 323 along third axis Z. In assembly, a screw 35 (the lower one in
According to the form shown, latch bolt 4 is mounted between first and second sidewalls 32 of base 3 and includes a latch 41 and a link 42. Latch 41 includes a first pivotal portion 411 on an end thereof and a second pivotal portion 412 between two ends of the latch 41. A pin 43 is extended through pin holes 329 of first and second sidewalls 32 of base 3 and first pivotal portion 411. Thus, the other end of latch 41 is pivotable between a latching position (
According to the form shown, follower plate 5A is mounted between first and second sidewalls 32 of base 3. Follower plate 5A is substantially U-shaped and includes first and second sidewalls 52 spaced along second axis Y and an intermediate portion 51 extending between first and second sidewalls 52. Latch bolt 4 is movably received between first and second sidewalls 52 of follower plate 5A. A tab or projection 511 is formed on intermediate portion 51. A spring 57 is attached between projection 511 of follower plate 5A and protrusion 314 of base 3 to bias follower plate 5A. First and second sidewalls 52 include aligned holes 521 in first ends 53 thereof and aligned slots 522 in second ends 54 thereof. Each of first and second sidewalls 52 further includes an engaging notch 524A in the form shown as a stepped portion adjacent first end 53 thereof. Each of first and second sidewalls 52 further includes a restraining slot 523A between hole 521 and slot 522. Restraining slot 523A of each of first and second sidewalls 52 includes upper and lower edges 523C and 523D spaced along first axis X and parallel, spaced, first and second lateral edges 523E and 523F extending between upper and lower edges 5234C and 523D, with an upper end of upper edge 523C connected to an upper end of first lateral edge 523E, with a lower end of upper edge 523C connected to an upper end of second lateral edge 523F and located between upper and lower ends of first lateral edge 523E along first axis X, and with first and second lateral edges 523E and 523F substantially parallel to vertical sections 327 of first guiding slots 323 of base 3 of bottom latch 25. First lateral edge 523E has a length along first axis X larger than a length of second lateral edge 523F along first axis X. Upper edge 523C is substantially parallel to inclined section 328 of each first guiding slot 323 of base 3. Lower edge 523D has an arcuate protrusion. An arcuate first corner 523G is formed between a lower end of second lateral edge 523F and an end of lower edge 523D. An arcuate second corner 523H is formed between the upper end of upper edge 523C and the upper end of first lateral edge 523E. An arcuate third corner 5231 is formed between a lower end of first lateral edge 523E and the other end of lower edge 523D. First and third corners 523G and 5231 are located on opposite sides of the protrusion of lower edge 523D along third axis Z. A spacing between first corner 523G and second corner 523H along first axis X is substantially equal to a spacing between third corner 5231 and second corner 523H along first axis X. Note that each restraining slot 523A is located between the corresponding engaging notch 524A and intermediate portion 51 of follower plate 5A along third axis Z and that each slot 522 of follower plate 5A extends in a direction parallel to first and second lateral edges 523E and 523F.
In the form shown, each of first and second sidewalls 52 of follower plate 5A of bottom latch 25 further includes an engagement hole 525A between slot 522 and engaging notch 524A. Engagement hole 525A is substantially a portion of a circle in cross section and is spaced from inclined slot 523 along third axis Z. Pin 55 is parallel to pins 43 and 44 and extended through first sliding slots 321 of base 3, holes 521 of follower plate 5, and holes 423 of link 42. Thus, an end of the follower plate 5 is pivotably connected to second end 422 of link 42. Note that pin 43 is extended through pin holes 329 of first and second sidewalls 32 of base 3 and first pivotal portion 411 and that pin 44 is extended through holes 425 of link 42 and second pivotal portion 412 of latch 41.
According to the form shown, linking rod 6 is in the form of a screw rod and includes a first end 61 without threading and a second end 62. First end 61 has a transverse hole 611 perpendicular to a longitudinal axis of linking rod 6. Second end 62 of linking rod 6 is connected to lower end 233 of lower vertical rod 232 to move therewith. It can be appreciated that second end 62 of linking rod 6 can be integrally formed with lower end 233 of lower vertical rod 232. A pin 56 parallel to pins 43, 44, and 55 is extended through second sliding slots 322 of base 3, slots 522 of follower plate 5, and transverse hole 611 of first end 61 of linking rod 6. Thus, follower plate 5A can be moved in the vertical direction together with linking rod 6 to move latch 41 between the unlatching position and the latching position when touch bar 22 is pressed. When latch 41 is in the latching position (
Locking device 7 is mounted on base 3 to lock latch 41 in the latching position or the unlatching position. Due to provision of locking device 7, top latch 24 and bottom latch 25 can be unlatched only when touch bar 22 is pressed. A deadlocking effect is, thus, provided.
According to the form shown, locking device 7 includes a safety plate 71A, a positioning pin 72, and a spring 74 in the form shown as a tension spring. Safety plate 71A is movably received between first and second sidewalls 52 of follower plate 5A and includes two sidewalls 712 spaced along second axis Y and interconnected by an interconnecting section 711. Each sidewall 712 includes first and second ends 713 and 714. Aligned holes 717 are defined in second ends 714 of sidewalls 712. Sidewalls 712 further include aligned holes 716 between first and second ends 713 and 714 thereof. Pin 56 is extended through second sliding slots 322 of base 3, slots 522 of follower plate 5A, holes 717 of safety plate 71A, and transverse hole 611 of first end 61 of linking rod 6. Thus, follower plate 5A can be moved along first axis X together with linking rod 6 to move latch 41 of bottom latch 25 between the unlatching position and the latching position. Furthermore, safety plate 71A can move along first axis X together with linking rod 6. A pin 73 is extended through first guiding slots 323 of base 3, restraining slots 523A of follower plate 5A, and holes 716 of safety plate 71A. Follower plate 5A can move relative to pin 73 along first axis X through a distance substantially the same as the spacing between the second and third corners 523H and 5231. When pin 73 is moving between first and second lateral edges 523E and 523F of each restraining slot 523A and along vertical sections 327 and inclined sections 328 of first guiding slots 323, safety plate 71A pivots about a pivot axis defined by pin 56 while moving upward or downward along first axis X. Pivotal movement of safety plate 71 A is limited due to limitation to pin 73 of safety plate 71A by restraining slots 523A of follower plate 5A and first guiding slots 323 of base 3.
According to the form shown, each sidewall 712 of safety plate 71A further includes an engaging notch 715 and a lug 718 between engaging notch 715 and second end 714. Lugs 718 are aligned along second axis Y and include aligned holes 719. Engaging notches 715 can engage with positioning pin 72 (
Bottom latch 25 utilizing the latch assembly of
When touch bar 22 is pressed, follower plate 5A is not moved when lower vertical rod 232 and linking rod 6 are moved upward away from latch 41 through a travel slightly smaller than a length of slot 522 of follower plate 5A along first axis X, but safety plate 71A moves away from latch 41 along first axis X relative to follower plate 5A. First ends 713 of safety plate 71A are actuated by pin 73 to cause pivotal movement of engaging notches 715 away from positioning pin 72. Pin 73 also moves toward second corners 523H of restraining slots 523A. When pin 73 reaches an intersection between vertical section 327 and inclined section 328 of each first guiding slot 323, pin 73 abuts first lateral side 523E and is between second and third corners 523H and 523I (
After pin 56 reaches upper ends of slots 522, pin 73 is located in vertical sections 327 of first guiding slots 323 and adjacent to vertical sections 327, and first ends 713 of safety plate 71A are located on a side of positioning pin 72. In this case, further upward movement of linking rod 6 away from latch 41 along first axis X causes follower plate 5A to move upward together with linking rod 6, which in turn, causes upward pivotal movement of link 42 about the pivot axis defined by pin 44. When pin 56 reaches upper ends of second sliding slots 322, pin 73 is located in second corners 523H of restraining slots 523A and in distal ends of vertical sections 327 of first guiding slots 323 (
When latch 41 of bottom latch 25 is in the unlatching position, positioning pin 72 is biased by spring 74 to engage with engaging notches 524A of follower plate 5A so that follower plate 5A can not move towards latch 41 along first axis X, reliably retaining latch 41 in the unlatching position. This effectively avoids latch 41 of bottom latch 25 from extending outside of base 3 due to the plays of the parts of bottom latch 25 after assembly. As a result, the interference between latch 41 and the ground 12 while door lock 2 is unlatched can be effectively avoided. It can be appreciated that the idle travel of pin 56 in slots 522 of follower plate 5A provides a burglarproof effect. Particularly, when latch 41 of top latch 24 is pivoted through a small angle due to picking, upward movement of link 42 and follower plate 5A along first axis X is smaller than or equal to the length of slots 522 along first axis X without causing unlatching of latch bolt 4.
When touch bar 22 is released, linking rod 6 returns to its original position, and pin 56 moves towards latch 41 of bottom latch 25 along first axis X through a travel substantially the same as the length of slots 522 of follower plate 5A along first axis X (
According to the form shown, the latch assembly further includes a first safety device 801A (
Second end 807 of first sleeve 803 of first safety device 801A is threaded into second hole section 837 of second sleeve 817 and engaged with inner threading 855. An end face of second end 807 of first sleeve 803 abuts second abutment face 853 of second sleeve 817 (
According to the form shown, first safety device 801A further includes first and second stops 877A and 877B respectively mounted in first and second sleeves 803 and 817. First and second stops 877A and 877B are made of a material having a melting point lower than firs and second sleeves 803 and 817, such as plastic. Each of first and second stops 877A and 877B has two ends 879 and a through-hole 891 extending from an end 879 through the other end 879. First stop 877A has an outer diameter slightly smaller than the inner diameter of larger section 811 of first sleeve 803. First stop 877A is received in larger section 811 of first stop 877A, with an end 879 abutting shoulder 815. Second stop 877B has an outer diameter smaller than the inner diameter of intermediate hole section 839 of second sleeve 817. Second stop 877B is received in intermediate hole section 839 of second sleeve 817, with an end 879 abutting first abutment face 851. A length of second stop 877B along second axis Y is equal to a length of intermediate hole section 839 of second sleeve 817. The melting point of each of first and second safety pins 857A and 857B are higher than that of first and second stops 877A and 877B.
According to the form shown, first safety device 801A further includes first and second safety pins 857A and 857B respectively mounted in first and second sleeves 803 and 817. Each of first and second safety pins 857A and 857B has a cylindrical shank 859 and a flange 871 on an end of shank 859 and having an end face 875. Shank 859 further has a distal end 873 away from flange 871.
First safety pin 857A is mounted in receiving hole 809 of first sleeve 803, with shank 859 of first safety pin 857A extending through through-hole 891 of first stop 877A. A length of shank 859 along second axis is equal to a sum of a length of first stop 877A and a length of smaller section 813 of receiving hole 809 along second axis Y. An outer diameter of shank 859 of first safety pin 857A is slightly smaller than the inner diameter of smaller section 813 of receiving hole 809 of first sleeve 803 and slightly smaller than through-hole 891 of first stop 877A. An outer diameter of flange 871 of first safety pin 857A is slightly smaller than the inner diameter of larger section 811 of receiving hole 809 of first sleeve 803 but larger than the inner diameter of through-hole 891 of first stop 877A, such that flange 871 of first safety pin 857A abuts an end 879 of first stop 877A distant to shoulder 815. Furthermore, distal end 873 of shank 859 is extended through smaller section 813 of first sleeve 803, and an end face of distal end 873 of shank 859 of first safety pin 857A is flush with the end face of first end 805 of first sleeve 803.
Second safety pin 857B is mounted in mounting hole 833 of second sleeve 817. A length of shank 859 of second safety pin 857B along second axis Y is equal to the sum of a length of second stop 877B and a length of first hole section 835 of mounting hole 833 along second axis Y. An outer diameter of shank 859 of second safety pin 857B is slightly smaller than the inner diameter of first hole section 835 of mounting hole 833 of second sleeve 817 and slightly smaller than the inner diameter of through-hole 891 of second stop 877B. An outer diameter of flange 871 of second safety pin 857B is slightly smaller than the inner diameter of second hole section 837 of mounting hole 833 of second sleeve 817 but larger than the inner diameter of through-hole 891 of second stop 877B, such that flange 871 of second safety pin 857B abuts an end 879 of second stop 877B distant to first abutment face 851. Furthermore, distal end 873 of shank 859 of second safety pin 857B is extended through first hole section 835 of second sleeve 817, and an end face of distal end 873 of shank 859 of second safety pin 857B is flush with the end face of first end 819 of second sleeve 817.
According to the form shown, first safety device 801A further includes a safety spring 893 mounted in larger section 811 of first sleeve 803 and having first and second ends 895 and 897. First end 895 of safety spring 893 presses against end face 875 of first safety pin 857A, and second end 897 of safety spring 893 presses against end face 875 of second safety pin 857B (
Base 3 of bottom latch 25 shown in
After adding some parts, bottom latch 25 can form a surfaced-type top latch 24 for door lock 2. According to the form shown in
According to the form shown, locking device 7 of top latch 24 includes a safety plate 71B that is substantially the same as safety plate 71A except that the shape of safety plate 71B is slightly different from that of safety plate 71A. First end 805 of first sleeve 803 and first end 819 of second sleeve 817 of second safety device 801B respectively extend through holes 719 of lugs 718 of safety plate 71B into engagement holes 525B of follower plate 5B of top latch 24. Thus, follower plate 5B can move together with linking rod 6 along first axis X to allow movement of latch 41 between the latching position and the unlatching position. Furthermore, safety plate 71B can move jointly with linking rod 6 or move jointly with follower plate 5B. Pin 73 of top latch 24 extends through first guiding slots 323 of base 3, restraining slots 523B of follower plate 5B and holes 716 of safety plate 71B. When pin 73 is moving between first and second lateral edges 523E and 523F of each restraining slot 523B and along vertical sections 327 and inclined sections 328 of first guiding slots 323, safety plate 71B pivots about a pivot axis defined by pin 56 while moving upward or downward along first axis X. Pivotal movement of safety plate 71B is limited due to limitation to pin 73 of safety plate 71B by restraining slots 523B of follower plate 5B and first guiding slots 323 of base 3.
According to the form shown, top latch 24 further includes a guard plate 8 mounted between first ends 33 of first and second sidewalls 32 of base 3. Guard plate 8 includes two sidewalls 85 spaced align second axis Y and interconnected by an interconnecting section 86 therebetween. Each sidewall 85 includes first and second ends 81 and 82 and aligned holes 87 between first and second ends 81 and 82, providing a pivotal portion 84 between first and second ends 81 and 82 of each sidewall 85. Pin 43 is extended through pin holes 329 of base 3, first pivotal portion 411 of latch bolt 4, and holes 87 of guard plate 8, allowing first ends 81 of sidewalls 85 and interconnecting section 86 interconnected between first ends 81 to pivot outside base 3. Second end 82 of each sidewall 85 has a notch 83 that can be in contact with and movable together with positioning pin 72 of locking device 7.
With reference to
When the touch bar 22 is pressed to move upper vertical rod 231 downward and to move lower vertical rod 232 upward along first axis X, linking rod 6 carries safety plate 71B downward along first axis X away from latch 41. Pin 56 does not actuate follower plate 5B when the travel of pin 56 along first axis X is smaller than the length of slots 522 of follower plate 5B along first axis X. Second safety device 801B moves together with safety plate 71B. First end 805 of first sleeve 803 and first end 819 of second sleeve 817 of second safety device 801B move from reduced ends 527 to enlarged ends 529 of engagement holes 525B of follower plate 5B. When pin 73 reaches an intersection of vertical sections 327 and inclined section 328 of each first guiding slot 323 of base 3, pin 73 is located in an end of each restraining slot 523B of follower plate 5B. Safety plate 71B pivots about the pivot axis defined by pin 56 to disengage engaging notches 715 of safety plate 71B from positioning pin 72 while pin 73 is moving along restraining slots 523B. Thus, when linking rod 6 continues moving away from latch 41 of top latch 24 and actuates pin 56, pin 56 presses against a wall of each slot 522, causing follower plate 5B to move away from latch 41 of top latch 24, moving latch 41 from the latching position to the unlatching position. At the same time, follower plate 5B, safety plate 71B and second safety device 801B move jointly away from latch 41 of top latch 24 until latch 41 reaches its unlatching position. When latch 41 of top latch 24 is in the unlatching position, first end 805 of first sleeve 803 and first end 819 of second sleeve 817 of second safety device 801B are in enlarged ends 529 of engagement holes 525B of follower plate 5B. When pin 73 is in distal ends of vertical sections 327 of first guiding slots 323, latch 41 is in the unlatching position, and first and second safety pins 857A and 857B of second safety device 801B are not aligned with positioning holes 325 of base 3 of top latch 24 (
When latch 41 of top latch 24 is retained in the latching position, release of touch bar 22 of door lock 2 can not return latch 41 of bottom latch 25 to its latching position. Specifically, when latch 41 of top latch 24 is retained in the latching position, follower plate 5B can not move along first axis X, such that linking rod 6 of top latch 24 and upper vertical rod 231 can not move along first axis X, either. In this case, when touch bar 22 is released, the transmission mechanism of door lock 2 can not move lower vertical rod 232, retaining latch 41 of bottom latch 25 in its latching position. When door 1 is closed and, thus, causes movement of latch 41 of top latch 24 from the unlatching position to the latching position, the transmission mechanism of door lock 2 actuates bottom latch 25, causing safety plate 71A to disengage positioning pin 72 of bottom latch 25 from engaging notches 715 of safety plate 71A. In this case, latch 41 of bottom latch 25 returns to its latching position together with latch 41 of top latch 24.
When closing door 1 in a state shown in
When latches 41 of top and bottom latches 24 and 25 are in their latching positions (
In a case that a fire occurs while latches 41 of top and bottom latches 24 and 25 are in the latching positions (
By providing restraining slots 523A in follower plate 5A of bottom latch 25 and first guiding slots 323 of base 3, safety plate 71A can move relative to follower plate 5A, so that engaging notches 715 of safety plate 71A can prevent picking of latch 41 of bottom latch 25. Furthermore, positioning pin 72 positions follower plate 5A when latch 41 is in the unlatching position, so that latch 41 in the unlatching position will not move beyond base 3 due to the plays of the parts of door lock 2 or bottom latch 25. Furthermore, first ends 713 of safety plate 71A can push positioning pin 72 to disengage positioning pin 72 from engaging notches 524A of follower plate 5A, allowing latch 41 of bottom latch 25 to move from the unlatching position to the latching position.
Now that the basic teachings of the present invention have been explained, many extensions and variations will be obvious to one having ordinary skill in the art. For example, follower plate 5A does not have to include engagement holes 525A, base 3 of bottom latch 3 does not have to include positioning holes 325, and bottom latch 25 does not have to include first safety device 801A. In this case, although latch 41 of bottom latch 25 can still be retained in the latching position during the fire as long as latch 41 of top latch 24 is retained in the latching position by second safety device 801B. Although top and bottom latches 24 and 25 including first and second safety devices 801A and 801B provide synergistic results, top and bottom latches 24 and 25 do not have to include first and second safety devices 801A and 801B according to user needs.
Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.
