GB2100786A - Emergency door lock - Google Patents

Abstract

An emergency door lock includes a bolt lath (11) mounted for movement between extended and withdrawn positions by means of a conventional key mechanism (12) and an auxiliary driving mechanism (13) for withdrawing the bolt lath (11), in emergency, without the use of a key. A spring loaded plunger (22) is normally restrained by a glass plate (21) so that a spring biased operating member (18) is held in an inoperative position in contact with a fixed abutment (19). When the plunger (22) is released by breaking of the glass, the operating member (18) is moved with the plunger (22) into an operative position in which it engages an abutment (31) on the bolt lath (11) to drive the latter to its retracted position. <IMAGE>

Description

SPECIFICATION Improvements relating to emergency door locks Description of Invention This invention relates to emergency door locks.

As the expression is used herein, an emergency door lock is one which is capable of being opened in either of two ways, namely normally by the use of a key, or in an emergency without the use of a key.

For security purposes, emergency opening of the lock must leave a visual indication and involve some deliberate or specific action on the part of a person opening the door so as to avoid so far as possible the risk of inadvertent opening.

One common arrangement provides some form of manual operation mechanism within a glazed housing. In an emergency, the glass is broken and the mechanism is manually operated to withdraw a bolt lath of the lock so as to enable the door to be opened.

It is an object of the invention to provide a new or improved emergency door lock which is simpler and safer to operate than such previous type.

According to the invention there is provided an emergency door lock comprising a housing, a bolt lath mounted for movement between an extended and a withdrawn position relative to said housing to lock and unlock the door respectively, keyoperable driving means for driving the bolt lath between said extended and withdrawn positions, and auxiliary driving means for driving the bolt lath from the extended position to the withdrawn position, wherein said auxiliary driving means includes an operating member with resilient means tending to move the operating member in a direction corresponding to movement of the bolt lath into the withdrawn position and a spring loaded member which is normally held by means of a frangible member in such a position that said operating member engages a fixed abutment and is thereby rendered inoperative, breakage of such frangible member allowing said spring loaded member to move to a position in which said operating member is disengaged from said fixed abutment and acts on said bolt lath to withdraw the latter.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: FIGURE 1 is a sectional view of an emergency door lock in the locked condition, and omitting certain parts for clarity; FIGURE 2 is a vertical section on the line Il-Il of Figure 1; FIGURE 3 is a horizontal section on the line Ill-Ill of Figure 1 but showing the lock in its normal withdrawn or unlocked condition; FIGURE 4 is a sectional view similar to that of Figure 1 and showing the lock in an unlocked condition following emergency operation; and FIGURE 5 is a section on the line IV-IV of Figure 4 also during emergency operation.

The illustrated embodiment of emergency door lock shown in the accompanying drawings comprises a housing 10, a bolt 11 a carried on a lath 11 which is slidably mounted in the housing, a key-operable lock mechanism generally indicated at 12 and an auxiliary driving mechanism, generally indicated at 13, which is operable in an emergency and which does not require the use of a key to withdraw the bolt lath.

The withdrawn condition of the bolt lath is shown in Figures 3, 4 and 5 of the drawings.

The lock mechanism 12 as illustrated is of the conventional lever type in which one or more levers 14 having suitable gates 1 5 which cooperate with a stud 15a on the bolt, are raised by specific amounts by means of a key (not shown) which is inserted through the keyhole 1 6 and rotated to engage with such lever or levers. The key simultaneously lifts the lever or levers 14 and engages the bolt lath at the recess 1 7 to move it into the extended position shown in Figure 1, or the withdrawn position shown in Figure 3. Thus, the lock can be used in the normal manner by a key holder to lock or unlock the door.

However, in an emergency, such as a fire, the lock is operable by the auxiliary driving mechanism 13 which includes a pivoted arm 1 8 mounted on the casing at a point intermediate its ends. Normally the arm 18 is positioned adjacent to one side of the housing 10, as best seen in Figures 2 and 3, and at its upper end bears against a fixed abutment 1 9 carried at that side of the housing.A tension spring 30 acts between the other end of the arm 1 8 and a fixed point in the housing so that the upper end of the arm is biased into contact with the fixed abutment 1 9. Under these conditions, the arm 1 8 is inoperative and the emergency door lock can be operated normally by means of a key, without any effect on the arm 1 8 as the bolt lath 11 is operated by the key.

However, the arm 18 will automatically be driven into the position shown in Figures 4 and 5 if the emergency release mechanism hereinafter described is operated, and this will cause the bolt lath 11 to be withdrawn so as to enable the door to be opened without the use of a key.

At the front face of the housing 1 O, a frangible member is provided. Typically, this will be a sheet of glass or other similar material, which is shown in Figure 3 and 5 at 21. Behind the frangible sheet there is a captive plunger 22 which has a head 23 trapping a coil spring 24 under compression. The plunger 22 extends through the side of the housing opposite to that at which the fixed abutment 1 9 is provided. The plunger is provided with an end member 27 at the inner end of the plunger. The end member 27 is slidably located on a location pin 29 carried by the housing 10 on the pivotal axis of the arm 1 8. The pin 29 also extends into a bore 26 at the inner end of the plunger 22 itself. An annular collar 28 on the arm 18 is arranged coaxially with the pin 29 and is secured to the end member 27.

The spring loaded plunger 22 is biased by means of the coil spring 24 against the glass sheet 21, and whilst the latter remains intact, it is held in the condition shown in Figure 2, with the end member 27 holding the arm 1 8 against the rear side of the housing 10 so that at the upper end the arm 1 8 engages the abutment 1 9.

The operation of the plunger 22 is as follows.

When the glass 21 is broken, as shown in Figure 5, the compression spring 24 forces the plunger 22 outwardly. The end member 27 and collar 28.

and thus the arm 18, are also moved outwardly until the collar 28 engages the front side of the housing 10 whereby the plunger is held captive.

The upper end of the arm 1 8 is thus disengaged from the fixed abutment 1 9 and is free to move in the clockwise direction from the position shown in Figure 1 under the action of the tension spring 30.

Movement of the arm 1 8 out of engagement with the fixed abutment 1 9 causes it to engage a further abutment pin 31 provided on the bolt lath 11 and thereby exert a force on the bolt lath in the direction required to withdraw the bolt without use of the key mechanism. To enable the bolt lath to move under these circumstances, the lever 14 is lifted by engagement of the abutment pin 31 carried by the lath 11 with an inclined cam face 33 on the lever thereby lifting the lever or levers 14 so that the bolt lath 11 is withdrawn to the condition shown in Figures 4 and 5 by means of the spring 32.

It is particularly to be observed that withdrawal of the bolt lath 11 follows automatically as a consequence of breakage of the glass sheet 21, without any further action being necessary on the part of the user. This is particularly desirable since, in conditions of emergency the user may not always be able to read operating instructions relating to the manual operation of a releasing member as required in some earlier types of emergency lock, and moreover insofar as access to such a manual operating member could only be obtained by breaking the glass sheet, there is in such system also a risk that the user may injure himself when operating such manual member.

It is also to be noted that the only force acting on the glass sheet 21 is that exerted by the coil spring 24. It is not necessary for the glass 21 to be capable of withstanding the force exerted by the leaf spring 30. This makes it possible to use glass of relatively reduced thickness which can readily be broken by a user with little risk of injury, whilst simultaneously permitting the spring 30 to be made strong enough to ensure that sufficient force is applied to the bolt lath to withdraw the latter even if it is somewhat stiff from lack of use, or as a result of frictional engagement with a keeper with which it co-operates in the extended condition.

The embodiment of emergency lock illustrated can be re-set by restoring the arm 18 to its initial position by means of, for example, a screwdriver inserted through an aperture 34 provided for this purpose in the forend of the housing 10 and then forcing the plunger 22 back to the conditions shown in Figure 3 and replacing the broken glass.

Whilst the illustrated embodiment utilises a key-operated lever lock mechanism, it will be appreciated that other types of conventional lock mechanism may be employed.

The invention provides an emergency door lock which can be operated extremely rapidly by persons not familiar with the type of lock concerned, since all that is required is that the glass is broken, and the remainder of the operation follows automatically under the control of the spring 30 in the illustrated embodiment, without any further action being necessary on the part of the user. If the glass 21 is transparent, the auxiliary driving mechanism for use in emergency can be inspected visually from time-to-time, and normal usage of the lock by means of a key will in no way affect or cause any wear in the auxiliary driving mechanism.

Claims (6)

1. An emergency door lock comprising a housing, a bolt lath mounted for movement between an extended and a withdrawn position relative to said housing to lock and unlock the door respectively, key-operable driving means for driving the bolt lath between said extended and withdrawn positions, and auxiliary driving means for driving the bolt lath from the extended position to the withdrawn position, wherein said auxiliary driving means includes an operating member with resilient means tending to move the operating member in a direction corresponding to movement of the bolt lath into the withdrawn position and a spring loaded member which is normally held by means of a frangible member in such a position that said operating member engages a fixed abutment and is thereby rendered inoperative, breakage of such frangible member allowing said spring loaded member to move to a position in which said operating member is disengaged from said fixed abutment and acts on said bolt lath to withdraw the latter.

2. A lock according to Claim 1 wherein the operating member is mounted for pivotal movement about an axis which is coaxial with the spring loaded member, the operating member being secured to the spring loaded member so as to be moved laterally when said frangible member is broken.

3. A lock according to Claim 2 wherein said operating member is movable laterally clear of said fixed abutment and into contact with an abutment carried by said bolt lath.

4. A lock according to Claim 2 or Claim 3 wherein said operating member is pivoted at a point intermediate its ends and said resilient means comprises a spring acting between one end of said operating member and a fixed point on the housing.

5. An emergency door lock substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

6. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.