Anti-pick latch assembly

A latch assembly comprising:

• a base (20) including two sidewalls (22) and an intermediate wall (38) extending between the two sidewalls (22), with each of the two sidewalls (22) including first, second, and third engagement holes (28, 30, 32), with the second engagement hole (30) located between the first engagement hole (28) and the third engagement hole (32) along a first axis (X), with first and second slots (36, 43) defined in the intermediate wall (38) and spaced from each other along the first axis (X), with the intermediate wall (38) of the base (20) adapted to be mounted to an end face (291) of a follower door (275) of a double door (257), with the follower door (275) including an interior space (293), with the two sidewalls (22) adapted to be received in the interior space (293) of the follower door (275), with the follower door (275) pivotable between a closed position and an open position;
• a movable member (50) movably received between the two sidewalls (22) of the base (20), with the movable member (50) including two lateral walls (52) spaced from each other along a second axis (Y) perpendicular to the first axis (X), with the movable member (50) further including a connecting portion (66) extending between the two lateral walls (52), with each of the two lateral walls (52) including a first end (54) and a second end (56) spaced from the first end (54) along the first axis (X), with a first sliding groove (58) defined in the first end (54) of each of the two lateral walls (52), with a second sliding groove (60) defined between the second end (56) and the first sliding grooves (58) of each of the two lateral walls (52), with the connecting portion (66) including first and second ends (66A, 66B) spaced from each other along the first axis (X), with an actuating groove (70) defined in the connecting portion (66) and located between the first end (66A) of the connecting portion (66) and the second sliding groove (60) of each of the two lateral walls (52) along the first axis (X), with the first engagement holes (28) of the two sidewalls (22) of the base (20) aligned with the first sliding grooves (58) of the two lateral walls (52) of the movable member (50), with the second engagement holes (30) of the two sidewalls (22) of the base (20) aligned with the second sliding grooves (60) of the two lateral walls (52) of the movable member (50), with the actuating groove (70) aligned with the second slot (43);
• a first pin (88) extending through the first engagement holes (28) of the two sidewalls (22) of the base (20) and the first sliding grooves (58) of the two lateral walls (52) of the movable member (50);
• a second pin (89) extending through the second engagement holes (30) of the two sidewalls (22) of the base (20) and the second sliding grooves (60) of the two lateral walls (52) of the movable member (50), with the movable member (50) movable between an engagement position and a disengagement position along the first axis (X), with a spacing between the first end (66A) of the connecting portion (66) of the movable member (50) in the engagement position and the first end (24) of each of the two sidewalls (22) of the base (20) being smaller than a spacing between the first end (66A) of the connecting portion (66) of the movable member (50) in the disengagement position and the first end (24) of each of the two sidewalls (22) of the base (20), with the actuating groove (70) remaining in a length of the second slot (43) along the first axis (X);
• a limiting member (90) pivotably received in the base (20) and having an outer periphery (97), with the limiting member (90) further including an engagement end (94) and a pivotal portion (96), with a first protrusion (92) formed on the outer periphery (97) and located adjacent to the pivotal portion (96), with the engagement end (94) facing the intermediate wall (38) of the base (20);
• a third pin (91) extending through the third engagement holes (32) of the two sidewalls (22) of the base (20) and the pivotal portion (96) of the limiting member (90), with the limiting member (90) pivotable between a locking position and an unlocking position about a pivot axis defined by the third pin (91);
• a limiting frame (101) fixed between the two sidewalls (22) of the base (20), with the limiting frame (101) including a first wall (103) and a second wall (113) spaced from the first wall (103) along the first axis (X), with the limiting frame (101) further including a connecting wall (119) extending between the first and second walls (103, 113), with the first wall (103) including an inner face (103A) and an outer face (103B) spaced from the inner face (103A) along the first axis (X), with a slot (111) extending from the inner face (103A) through the outer face (103B) of the first wall (103), with the first and second walls (103, 113) fixed to the intermediate wall (38) of the base (20), with the first protrusion (92) of the limiting member (90) extending through the slot (111) and received between the first and second walls (103, 113), with the engagement end (94) of the limiting member (90) located outside of the limiting frame (101);
• an actuation latch (131) movably received in the first slot (36) of the base (20), with the actuation latch (131) including a base portion (132) having first and second ends (133, 137) spaced from each other along a third axis (Z) perpendicular to the first and second axes (X, Y), with the base portion (132) further including first and second sides (144, 146) spaced from each other along the first axis (X), with a wedge (134) formed on the second end (137) of the actuation latch (131), with a groove (142) formed in the first side (144) but spaced from the second side (146), with the groove (142) including a bottom wall having an inclined section (148) intersecting with the first side (144), with the actuation latch (131) movable along the third axis (Z) between a releasing position in which the wedge (134) is located outside of the base (20) and a pressing position in which the wedge (134) is received in the base (20), with the actuation latch (131) adapted to be actuated by an end face (273) of a primary door (259) of the double door (257), wherein when the follower door (275) is in the closed position and when the end face (273) of the primary door (259) is aligned with the end face (291) of the follower door (275), the end face (273) of the primary door (259) presses against the actuation latch (131), moving the actuation latch (131) from the releasing position to the pressing position;
• a first spring (335) mounted between the actuating latch (131) and the connecting wall (119) of the limiting frame (101), with the first spring (335) biasing the actuation latch (131) from the pressing position to the releasing position;
• a locking block (139) fixed to the movable member (50), with the locking block (139) including a locking hole (153), with the locking block (139) and the movable member (50) jointly movable between the engagement position and the disengagement position, with the locking block (139) spaced from the third pin (91) along the first axis (X);
• a second spring (171) mounted between the locking block (139) and the second pin (89), with the second spring (171) biasing the locking block (139) and the movable member (50) from the disengagement position to the engagement position;
• a connecting rod (215) including a first end (217) engaged in the locking hole (153) of the locking block (139) and a second end (219);
• a latch (231) including an engagement end (233) fixed to the second end (219) of the connecting rod (215), with the latch (231) further including a locking end (235) having a slant face (236), with the latch (231) movable between a latching position and an unlatching position along the first axis (X), with the locking end (235) of the latch (231) in the unlatching position being adapted to be received in the follower door (275), with the locking end (235) of the latch (231) in the latching position adapted to extend out of the follower door (275) into a groove (37) in a door frame (31) to which the double door (257) is pivotably mounted;
• wherein when the follower door (275) is in the open position, the latch (231) is not aligned with the groove (37), wherein when the follower door (275) is in the closed position, the latch (231) is aligned with the groove (37),
• wherein when the follower door (275) moves from the open position to the closed position, the slant face (236) of the latch (231) presses against the door frame (31), causing movement of the latch (231) from the latching position to the unlatching position, and the latch (231) is moved to the latching position under action of the second spring (171) when the follower door (275) is in the closed position,
• wherein when the end face (273) of the primary door (259) is not aligned with the end face (291) of the follower door (275), the actuation latch (131) is in the releasing position, the first protrusion (92) of the limiting member (90) abuts against the first side (144) of the actuation latch (131), the limiting member (90) is in the unlocking position, the engagement end (94) of the limiting member (90) is located outside of a movement path of the movable member (50) between the engagement position and the disengagement position, allowing the movable member (50) to be moved from the engagement position to the disengagement position via the actuating groove (70) to cause movement of the latch (231) from the latching position to the unlatching position,
• wherein when the end face (273) of the primary door (259) is aligned with the end face (291) of the follower door (275), the actuation latch (131) is in the pressing position and compresses the first spring (335), the groove (142) of the actuation latch (131) is aligned with the first protrusion (92) of the limiting member (90), the limiting member (90) is in the locking position, the engagement end (94) of the limiting member (90) is located in the movement path of the movable member (50), preventing the movable member (50) from being moved from the engagement position to the disengagement position via the actuating groove (70) to avoid the latch (231) from moving form the latching position to the unlatching position, avoiding picking of the latch (231),
• wherein when the actuation latch (131) is in the pressing position, if the primary door (259) is moved to a position in which the end face (273) of the primary door (259) is not aligned with the end face (291) of the follower door (275), the actuation latch (131) is moved by the first spring (335) from the pressing position to the releasing position, the first inclined section (148) of the actuation latch (131) pushes the first protrusion (92) of the limiting member (90), causing movement of the limiting member (90) from the locking position to the unlocking position about the pivot axis defined by the third pin (91), allowing movement of the movable member (50) from the engagement position to the disengagement position.