GB2093905A - Emergency door locks - Google Patents

Abstract

An emergency door lock includes a lock bolt (11) mounted for movement between extended and withdrawn positions by means of a conventional key-operable driving mechanism (12) is provided with an auxiliary driving mechanism (13) for withdrawing the bolt (11), in emergency, without the use of a key. A spring loaded plunger (22) is normally restrained by a glass plate (21) in such a position that an abutment element (27) carried by the plunger holds a leaf spring (30) in a stressed condition. When the plunger (22) is released by breakage of the glass (21), the leaf spring (30) is allowed to move into contact with a pivoted cam (18) which drives the bolt (11) into its retracted position. <IMAGE>

Description

SPECIFICATION Improvements relating to emergency door locks This invention relates to emergency door locks.

As the experession 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is provided an emergency door lock comprising a housing, a bolt lath mounted for movement between an extended and a withdrawn position relative to said housing to lock and unlock the door respectively, keyoperable driving means for driving the bolt lath between said extended and withdrawn positions, and auxiliary driving means for driving the bolt lath between the extended and withdrawn positions, wherein said auxiliary driving means includes resilient operating means tending to operate the auxiliary driving means to drive the bolt lath to the withdrawn position, and a frangible member holding an abutment element in a first or disabling position in which it obstructs operation of the auxiliary driving means, breakage of said frangible member allowing said abutment element to move to a second or enabling position in which said auxiliary driving means acts on the bolt lath and automatically moves it into its withdrawn position.

Preferably, the abutment element in its first or disabling position engages a movable component of the auxiliary driving means, and is arranged for movement to its second or enabling position in a direction transverse to the direction in which said movable component moves under the force of said resilient operating means.However, the arrangement may be such that a component of the force exerted by the resilient operating means also acts on the abutment element in such a sense as to assist or cause movement thereof to its second or enabling position when said frangible member is broken, but preferably resilient biasing means are provided to urge the abutment element into contact with the frangible member and move the abutment element into its enabling position when the frangible member is broken, such resilient biasing means operating independently of any force exerted on the abutment element by the resilient operating means.

The abutment element is preferably formed or provided on a plunger which is biased into engagement with said frangible member by said resilient biasing means, breakage of the frangible member permitting said biasing means to move the plunger so as to bring the abutment element into its enabling position, thereby enabling the auxiliary driving means to withdraw the bolt lath.

The abutment element preferably includes an inclined face which engages said movable component of the auxiliary driving means when the abutment element is in intermediate positions between said disabling and enabling positions, whereby the resilient operating means can be reset after operation by manual return of the abutment element to its disabling position.

The resilient operating means may comprise a leaf spring acting on a fixed part of the housing at one end and normally restrained at the other end by said abutment element.

The auxiliary driving means may include a linkage between said operating means and the bolt lath, and conveniently the abutment element in its disabling position engages the operating means to maintain the latter in a stressed condition. Said linkage may include a pivoted lever, one end of which engages in a notch formed in the bolt lath so that the lever moves with the bolt lath when the latter is operated by the keyoperated driving means, the other end of the lever moving away from the resilient operating means as the bolt lath is moved into its withdrawn position by said key-operated driving means.

Alternatively, the abutment element could engage the lever and hoid it in a position in which normal operation of the bolt lath by the keyoperated driving means is unhindered, the lever engaging the bolt lath and withdrawing same when the abutment element is moved to its enabling position. Indeed, instead of employing such a linkage, the resilient operating means could be arranged to engage directly with the bolt lath when the abutment element is in its enabling position, the abutment element when in its disabling position holding the resilient operating means out of contact with the bolt lath.

The key-operated driving means may comprise a lever lock mechanism. In this case, the auxiliary driving means may include a cam adapted to operate the lever lock mechanism by lifting the or each lever as the bolt lath is driven by the resilient operating means. The resilient operating means is preferably adapted to drive the cam as well as the bolt lath and conveniently the aforesaid lever is adapted to serve as said cam as well as driving the bolt lath.

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 secitional view of an emergency door lock in the locked condition, and omitting certain parts for clarity; Figure 2 is a sectional view similar to that of Figure 1 and showing the lack in an unlocked condition follwoing emergency operation; Figure 3 is a detail view of a plunger incorporated in the lock for emergency operation, the plunger being shown in its normal condition; and Figure 4 is a detail view of the plunger during emergency operation.

The illustrated embodiment of emergency door lock shown in the accompanying drawings comprises a housing 10, a bolt lath 11 which is slidably mountable in the housing, a key-operable Jock 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 Figure 2 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 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 1 4 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 2. Thus, the lock can be used in the normal manner by a key holder to lock or unlock the door.

However, during an emergency, such as a fire, the lock is operable by the auxiliary driving mechanism 1 3 which includes a lever-like cam 1 8 pivoted to the casing at 1 9. One end of the cam 1 8 acts on the lock mechanism by engaging in a recess 20 formed in the bolt lath 11 whilst simultaneously engaging the lever or levers 14, so that as the cam 1 8 is operated it simultaneously lifts the lever or levers, so as to free the bolt lath for movement and moves the bolt lath.

During normal use of the emergency door lock by means of a key, the lever-like cam 18 can pivot freely as the bolt lath is operated by the key, the upper end of the cam 18 remaining engaged within the recess 20.

However, the cam 1 8 will automatically be driven into the position shown in Figure 2 if the emergency release mechanism hereinafter to be described is operated, and this will cause the bolt lath 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 10, a frangible member is provided. Typically, this will be a sheet of glass or other similar material, which is shown in Figure 3 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 a plate 25 at a position adjacent to the end of the lever-like cam 18 remote from the bolt lath 11. The plunger is provided with an abutment element 27 which, in the illustrated embodiment, is threadably received within a bore 26 formed at the inner end of the plunger. The abutment element 27 has a tapered, generally conical head 28 and is slidably located on a location pin 29 carried by the housing 10.

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 3, with the abutment element 27 engaging the rear face of the housing 10.

A strong leaf spring 30 is mounted within the housing about a fixed peg 31 and has one limb 32 engaging against the housing, and the other limb 33 bearing against the tapered head 28 of the abutment element 27. In this condition, the abutment element 27 effectively disables the leaf spring 30 and holds the latter in a stressed condition in which the free end of the limb 33 is held clear of the lever-like cam 1 8. In the embodiment illustrated, the limb 33 of the leaf spring 30 engages against the larger radius end 35 of the tapered head 28. However, when the plunger is allowed to move to a second, or enabling position, hereinafter described, the limb 33 of the leaf spring 30 is free to move into engagement with the end of the lever-like cam 1 8 remote from the bolt lath 11.Accordingly, the leaf spring 30 serves as the operating means for the auxiliary driving means previously referred to at 1 3, in that it is capable of forcing the pivoted cam 1 8 in a direction such as to withdraw the bolt lath.

The operation of the plunger 22 is as follows.

When the glass 21 is broken, as shown in Figure 4, the compression spring 24 forces the plunger 22 outwardly until the wider end 35 of the head 28 of the abutment element 27 engages the plate 25, whereby the plunger is held captive. This allows the limb 33 of the leaf spring 30 to move in the anti-clockwise direction from the position shown in Figure 1 until it engages the smaller radius end 36 of the head. Since the head 28 is tapered, the pressure of the leaf spring 30 bearing thereon may afford a component of force to assist the outward movement of the plunger 22.

Accordingly, the limb 33 of the leaf spring 30 drives the cam 1 8 about the pin 19, thereby lifting the lever or levers 14 and withdrawing the bolt lath 11 to the condition shown in Figure 2.

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 realting 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 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 (with the possible addition of a further component of force derived from the leaf spring 30). It is not necessary for the glass 21 to be capable of withstanding the full 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 leaf 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 the keeper (not shown) with which it co-opeates in the extended condition.

The embodiment of emergency lock illustrated can be re-set by forcing the plunger 22 back to the condition shown in Figure 3 and replacing the broken glass. The tapered head 28 assists in this operation by affording a cam action which pushes the limb 33 of the leaf spring back to the condition shown in Figure 1.

However, the abutment element 27 need not include a head of tapered form. For example, the head may be simply of stepped form, having a shank portion of smaller radius (corresponding to the smaller end 36 as illustrated) and a flange portion (corresponding to the wider end 35 as illustrated). In this case, the leaf spring would have to be re-set by means of an appropriate tool before the plunger could be restored to its disabling position. The smaller radius shank portion of such abutment element could, in fact, be omitted if it is not considered to be necessary to limit movement of the limb 33 of the spring.- Likewise, the abutment element need not be of headed form if it is not required to be captively mounted in the housing, and in this case the abutment element could be afforded simply by the inner end of the plunger 22.

In stead of arranging for the abutment element 27 to engage the leaf spring 30, it would alternatively be possible to provide an abutment member which obstructs movement of the leverlike cam 18, and re-designing the bolt lath 11 so as to enable the latter to move to its withdrawn condition whilst the cam 18 remains in the position shown in Figure 1, being held in that position by the abutment element. Likewise, it would be possible to omit the lever-like cam 1 8 entirely and arrange for a leaf spring, acting in the opposite direction, to act directly on the bolt lath.

In further embodiments, the leaf spring 30 could be replaced by, for example, a coil spring acting on a carrier which is coupled to the bolt lath by means of a suitable lost motion connection whereby the bolt lath may be driven by the key so as to move the relative to the carrier in normal operation, the carrier being driven by such coil spring, in emergency operation so as to withdraw the bolt lath. In such a case, movement of the carrier could be obstructed by the plunger 22 or other similar arrangement.

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 leaf 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 visusally 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 (18)

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 between the extended and withdrawn positions, wherein said auxiliary driving means includes resilient operating means tending to operate the auxiliary driving means to drive the bolt lath to the withdrawn position, and a frangible member holding an abutment element in a first or disabling position in which it obstructs operation of the auxiliary driving means, breakage of said frangible member allowing said abutment element to move to a second or enabling position in which said auxiliary driving means acts on the bolt lath and automatically moves it into its withdrawn position.

2. A lock according to Claim 1 wherein the abutment element in its first or disabling position engages a movable component of the auxiliary driving means, and is arranged for movement to its second or enabling position in a direction transverse to the driection in which said movable component moves under the force of said resilient operating means.

3. A lock according to Claim 2 wherein a component of the force exerted by the resilient operating means also acts on the abutment element in such a sense as to assist or cause movement thereof to its second or enabling position when said frangible member is broken.

4. A lock according to any one of the preceding claims wherein resilient biasing means are provided to urge the abutment element into contact with the frangible member and move the abutment element into its enabling position when the frangible member is broken, such resilient biasing means operating independently of any force exerted on the abutment element by the resilient operating means.

5. A lock according to Claim 4 wherein the abutment element is formed or provided on a plunger which is biased into engagement with said frangible member by said resilient biasing means, breakage of the frangible member permitting said biasing means to move the plunger so as to bring the abutment element into its enabling position, thereby enabling the auxiliary driving means to withdraw the bolt lath.

6. A lock according to any one of Claims 2 to 5, wherein the abutment element includes an inclined face which engages said movable component of the auxiliary driving means when the abutment element is in intermediate positions between said disabling and enabling positions, whereby the resilient operating means can be reset after operation by manual return of the abutment element to its disabling position.

7. A lock according to any one of the preceding claims wherein the resilinet operating means comprises a leaf spring acting on a fixed part of the housing at one end and normally restrained at the other end by said abutment element.

8. A lock according to any one of the preceding claims wherein the auxiliary driving means includes a linkage between said opearting means and the bolt lath, and conveniently the abutment element in its disabling position engages the operating means to maintain the latter in a stressed condition.

9. A lock according to Claim 8 wherein said linkage includes a pivoted lever, one end of which engages in a notch formed in the bolt lath so that the lever moves with the bolt lath when the latter is operated by the key-operated driving means, the other end of the lever moving away from the resilient operating means as the bolt lath is moved into its withdrawn position by said keysperated driving means.

10. A lock according to any one of the preceding claims wherein said abutment element is arranged to engage said resilient operating means.

11. A lock according to Claim 8 or Claim 9 wherein the abutment element engages the lever and hold it in a position in which normal operation of the bolt lath by the key-operated driving means is unhindered, the lever engaging the bolt lath and withdrawing same when the abutment element is moved to its enabling position.

12. A lock according to any one of Claims 1 to 7 wherein the resilient operating means is arranged to engage directly with the bolt lath when the abutment element is in its enabling position, the abutment element when in its disabling position holding the resilient operating means out of contact with the bolt lath.

13. A lock according to any one of the preceding claims wherein the key-operated driving means comprises a lever lock mechanism.

14. A lock according to Claim 1 3 wherein the auxiliary driving means includes a cam adapted to operate the lever lock mechanism by lifting the or each lever as the bolt lath is driven by the resilient operating means.

1 5. A lock according to Claim 14 wherein the resilient operating means is adapted to drive both the cam and the bolt lath.

1 6. A lock according to Claim 1 5 wherein the lever is adapted to serve as said cam as well as driving the bolt lath.

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

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