Emergency Exit Lock Device

This invention relates to an exit device comprising a latch-bolt assembly mounted on one surface of a door member and a cooperating strike assembly mounted on a door frame member such as a mullion. More particularly, the invention relates to an exit device designed primarily for an outwardly opening metal door which will remain locked when subjected to severe distortions of the kind encountered in a fire or other major force.

It is recognized in the prior art that at times it is desirable, if not essential, to maintain a closure such as a door in a closed condition. For example, when an automobile is involved in an accident it is a common belief that it is best if the doors remain closed to prevent the occupants from being thrown from the automobile onto the roadway or roadside. It has been found, however, that in an accident where the automobile is subjected to substantial force that the doors of the automobile will swing open under the impact of the collision due to distortion of the door frame permitting the door latch to disengage from the door strike. Similarly, emergency or fire doors which preferably are to remain locked during a fire oftentimes spring open due to distortion of the door or door frame member, permitting the door latch to disengage from the door strike. Similarly, distortion and disengagement of door members can occur when excessive force is applied to a door member such as a result of the force of water being applied from a fire hose during a fire.

In the prior art, various attempts have been made to provide exit devices which preclude the accidental opening of a closure such as a door by distortion of a door member. U.S. Pat. No. 2,709,612 is directed to an exit device for use on an automobile door to prevent accidental opening of the door by distortion of the car frame. The disclosed device includes provisions for a door member which projects beyond a free or unhinged edge of the door and cooperating socket means in a doorjamb for reception of the door member when the door is closed. In order to provide the desired interlocking engagement, the outer free or projecting end of the door member is offset from its root portion in a direction vertically and/or inwardly with respect to the cooperating doorjamb to provide an overhang and the socket means is correspondingly formed in the jamb to receive the offset door member. In one preferred form, the closure device includes a lug or dovetail member secured to a free end of the door so as to project outwardly beyond and away from such edge a short distance, this member being adapted and arranged for reception in a cooperating socket member in the frame. Preferably the lug and its cooperating socket are placed as close to the door latch member as is conveniently possible to affect maximum resistance to edgewise separation at that point. U.S. Pat. No. 4,401,330 discloses a locking method of and means for securing or maintaining secured a closure such as a door when the door members are subjected to thermal distortion caused by a fire. It is stated that the opening or disengagement of the door latching device is caused because the door frame member such as a mullion which retains the door strike is fixed at its lower end to the floor and at the upper end to the ceiling. Upon heating the door member attempts to become elongated. However, because of being fixed the door member cannot expand, causing distortion and deformation and subsequent disengagement of the locking or latching device. To avoid this distortion and disengagement, the '330 patent suggests having a free space at either the top or bottom of the frame member so as to permit elongation without distortion. According to the disclosure of the patent a latch mechanism is provided which under normal conditions is always in disengagement but upon elongation due to thermal forces will become engaged and retain the door and door frame such as a mullion in locking relation. U.S. Pat. No. 4,437,693 discloses a latching mechanism which upon the presence of excessive heat as on the occurrence of fire has a cover which melts, allowing a blocking plate to slide into operative position to prevent retraction of the latching means and consequently preventing unlatching of the device. The patent provides for a kit member to enable the utilization of the blocking member in an existing door frame.

Although the aforesaid patents define the problem confronting the present applicant, the solutions to the problem are not completely acceptable because of complexity and/or the need for modifying the closure structure.

Accordingly, it is a primary object of the present invention to provide an exit device comprising a latch-bolt assembly and a cooperating strike assembly for locking a closure such as a door which will remain locked when subjected to distorting forces including thermal forces.

It is another object of the present invention to provide an exit device comprising a latch-bolt assembly and a cooperating strike assembly for locking a closure and maintaining the closure locked even when subjected to distorting forces which is simple and inexpensive to manufacture.

These and other objects of the present invention will become apparent from the following general description of the invention and the illustrated presently preferred embodiment as set forth in the drawing.

The objects of the present invention are accomplished by providing an exit device primarily designed for outwardly opening doors which comprises a rigid plate member having mounted thereon a latch-bolt assembly for anchoring to the surface of a door and a strike assembly for mounting on a door frame member or a mullion in operative association with the latch-bolt assembly. The front of the plate member includes projections positioned so that one of the projections will be on each side of the latch bolt of the mounted latch-bolt assembly. The strike assembly includes recesses for receiving the projections. The recesses in the strike assembly are configured in relation to the projections to allow vertical movement of the projections within the recesses by a predetermined distance before striking the walls of the recesses. In the event of a fire or other major distorting force, the projections, while being free to permit limited movement in a vertical direction, will restrict linear growth of the frame in the latch area by engagement of the projections with the walls of the recesses, thereby preventing excessive strain from occurring on the latch bolt which could cause disengagement of the latch bolt from the strike. Additionally, the projections in the recesses will limit the lateral movement of the strike and door frame member away from the latch assembly. The rigid face of the latch-bolt assembly will also limit inward movement of the strike and frame member toward the latch assembly.

Accordingly, in the presently disclosed device the latch-bolt assembly is prevented from becoming disengaged from the strike assembly even when subjected to major forces such as thermal forces caused by a fire, or other physical forces such as an impact from a collision or the like. The exit device of the present invention has application primarily with an outwardly opening door where the latch-bolt assembly is applied to one surface of the door.

The presently preferred embodiment of the invention is shown in the drawing wherein like parts are referred to by like numbers. In the drawing,

FIG. 1 is front elevational view illustrating a closure and wall member utilizing an exit device of the present invention;

FIG. 2 is an enlargement of a part of the assembly of FIG. 1;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is an exploded perspective view showing the latch-bolt assembly and strike assembly of the exit device of the present invention;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 3;

FIG. 6 is a sectional view taken along line 6--6 of FIG. 5;

FIG. 7 is a sectional view taken along line 7--7 of FIG. 5;

FIG. 8 is is a top view of the latch-bolt assembly for attachment to a door;

FIG. 9 is a view showing a first side of the latch-bolt assembly, partly fragmented for convenience;

FIG. 10 is a view showing the second side of the latch-bolt assembly, parts thereof being omitted for convenience;

FIG. 11 is a bottom view of the latch-bolt assembly;

FIG. 12 is an elevational view illustrating the exit device of the present invention on double doors; and

FIG. 13 is a sectional view taken along line 12--12 of FIG. 12.

FIGS. 1-3 illustrate a door 10, an emergency exit lock and actuator assembly indicated generally by reference numeral 12 utilizing the exit device of the present invention. As shown, door 10 has mounted on one surface 10a a housing 14 for retaining a latch-bolt assembly indicated generally by reference numeral 30, a cover 16 for latch-bolt assembly 30, and a push-bar 18 for actuating or releasing latch 32 of latch-bolt assembly 30. As seen in FIG. 3, a knob 34 is positioned at surface 10b of door 10, with the actuating mechanism therefor extending through the door. Strike assembly 50 is anchored to door frame member or mullion 20 in cooperative association with latch-bolt assembly 30.

It will be understood that although the assembly illustrated includes a knob 34, it may be preferable to simply use an internal lock mechanism, permitting the door to be opened from the outside with a key. At other times it may be desirable not to have either a knob or key mechanism. These aspects are not significant to the presently disclosed and claimed invention.

The exit device, as best seen from FIG. 4, includes latch-bolt assembly 30 and a strike assembly 50. Latch-bolt assembly 30 comprises a front or base plate 31 made of a rigid metal having projections or lugs 34 and 36 extending therefrom, a plurality of mounting holes 38 for mounting the base plate to a door or closure member 10, and a latch-bolt mechanism 40. The latch-bolt mechanism 40 includes a main latch bolt 32 and an auxiliary latch-bolt 33, both pivoting on pin member 35 associated with return spring 35a.

It is to be noted that the base plate 31 is of a heavy, rigid metal with mounting holes thereon, as best shown in FIGS. 8 and 9, being positioned on each side of pivot pin member 35, providing enhanced support preventing twisting of the assembly in the event of a major force such as a fire at a critical point. It is also to be noted that latch bolt 32 has a pin 32a spaced from pivot pin 35 on each side of the bolt 32 which ride in banana-type curves 32b, as best shown in FIGS. 9 and 10. Pins 32a, riding in banana-type curves 32b, prevent cocking of the mechanism in the event of a major force such as a fire.

As illustrated in FIG. 11, the latch-bolt assembly is secured to base plate 31 on the bottom side of the base plate with stakes 31a which are bent over and indented into a recess 31b of the base plate. Additional anchoring is provided at 31c as best shown at FIG. 11. The anchoring of stakes 31a with screw means 31d prevents the breaking away of the latch-bolt mechanism 40 from the base plate 31, again in the event of a major force such as a fire.

Strike assembly 50 includes anchoring or base plate 52 having a plurality of holes or slots 58 for mounting the assembly to a frame member. The assembly also includes recesses 54 and 56 for receiving projections 34 and 36 of the latch-bolt assembly 30. As illustrated, the recesses 54 and 56 are wider than projections 34 and 36, permitting limited vertical movement of the projections in the recesses. Assembly 50 also includes slot 51 and ramp 53 for receiving and retaining latch bolt 32, thereby holding the door closed.

As is apparent, front or base plate 31 constructed integrally with lugs or projections 34 and 36 can be conveniently manufactured as a unitized structure from a rigid metal. The latch-bolt assembly which is mounted on base plate 31 in accordance with the present invention can, in general, be any of the prior art latch-bolt assemblies such as shown and described in Williams, U.S. Pat. No. 3,877,262 assigned to the assignee of the present application, incorporated herein by reference. The latch-bolt assembly as illustrated in the drawing, however, is unique in view of the manner of anchoring the latch-bolt mechanism 40 to the base plate 31 by means of stakes 31a; in view of the manner of securing the latch-bolt 32 to the mechanism with pins 32a riding in curves 32b, and in the manner of securing the base plate 30 to the door member 10 at points directly opposite of the pivot pin 35 through holes 38. The strike assembly is also of unitized construction from a rigid metal.

FIGS. 12 and 13 are views similar to the views of FIGS. 1 and 3; however, in FIGS. 12 and 13 a double door assembly is illustrated. As shown in FIGS. 12 and 13, a strike assembly 50 is attached to opposite surfaces of mullion 20 for engagement with latch-bolt assembly 30.

The operation of the exit device of the present invention is best shown in FIGS. 5, 6, and 7. As shown, a door 10 has mounted on surface 10a a latch-bolt assembly 30 with fasteners 37. As best shown in FIG. 5, the door has a reinforcing plate 10c. To a door frame member 20 having a reinforcing plate 20a is attached a strike assembly 50 with fasteners 57. As best shown in FIG. 6, latch-bolt 32 by engagement with slot 51 and ramp 53 locks the door to the frame member. As shown in FIG. 5, when the door and frame are in locking engagement, projections 34 and 36 have space X for limited vertical movement within recesses 54 and 56. As shown in FIG. 7, the latch member 36 has space Y for limited inward lateral movement and space Z for limited outward lateral movement within recess 54.

In normal operations, the exit device of the present invention functions similar to any conventional mated latch bolt and strike assembly. However, when the presently disclosed device is subjected to a major distorting force of a type which normally will cause a hinging-type of action that can cause latch disengagement from the strike by the introduction of a camming angle, projections 34 and 36 on front plate 31 prevent door 10 from separation from the mullion 20 when the mullion bows toward the fire in the latched area by engaging the walls of recesses 54 and 56 in the strike assembly, forcing door 10 to move with mullion 20 in the same relative manner. Linear growth of mullion 20 during a fire is restricted in the latch area by projections 34 and 36 on plate 31 engaging the walls of the recesses 54 and 56 in the strike assembly, preventing excessive strain from occurring on latch bolt 32 and other components of the latch assembly as a result of the raised portions of the strike forcibly engaging the sides of the latch bolt. This restriction also prevents auxiliary latch 33 of the dead-locking mechanism from becoming disengaged from the strike projection which would allow the dead locking of the latch bolt to become inoperative. The projections limit lateral movement of the strike and mullion away from the latch assembly and by the rigid face of the latch assembly limit inward movement of the strike and mullion toward the latch assembly, thereby stabilizing the device.

The dead-locking mechanism generally illustrated in the drawing is fully illustrated and described in the aforesaid Williams, U.S. Pat. No. 3,877,262, primarily with reference to FIGS. 3 and 4 of the '262 patent as described at column 4, line 58, through column 5, line 33.

As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.