GB2051217A - Improvements in door bolts - Google Patents

Abstract

This invention relates to a door bolt of the type in which the tongue 78 is adapted to be held against a resilient load in a door locking position by means of a frangible member e.g. glass plate 65. A carrier 58 is provided, which is movable between an operative door locking position (shown) and a release position, with first resilient means 64 loading the carrier towards the release position, the frangible member 65 being located so that it engages with the carrier to hold the latter against its resilient loading. The tongue is mounted on the carrier for movement in the same sense as the carrier but relatively thereto and second resilient means 80 act between the carrier and the tongue and urging the tongue into the operative position. A manually operable overriding means e.g. lock 86 is provided for moving the tongue into a release position against the action of the second resilient means, lock detent 85 engages the tongue at 84. <IMAGE>

Description

SPECIFICATION Improvements in door bolts There is a known type of door bolt in which the tongue (or bolt proper) is adapted to be held against a resilient load in a door locking position by means of a frangible member (e.g. a glass plate). The purpose of this known construction is to provide a means of escape through the door in case of emergency. If the bolt is used to lock the door, to-prevent unauthorised entry, and an emergency arises, the frangible member can be broken, thereby allowing the tongue to move under its resilient load into the door release position.

It is the principal object of this invention to provide an improvement on this known type of door bolt, which will permit the door to be opened without breaking the frangible member. It will be appreciated that one of the draw-backs of the known door bolt is that the door has to remain permanently closed until the frangible member is broken. Another object of the invention is to provide a bolt which cannot be accidentally locked against release even in emergency, and a third object is to provide a bolt of compact construction which can be produced economically.

According to this invention a door bolt comprises a supporting structure; a carrier movable relatively to the supporting structure between an operative door locking position and a release position, there being first resilient means loading the carrier towards the release position; a frangible member located by the support structure in a manner such that it engages with the carrier, or with an element movable with the carrier, to hold the carrier against its resilient loading in the operative position, whereby the carrier is adapted to be released to move into the release position if the frangible member is broken; a tongue mounted on the carrier for movement in the same sense as, but relatively to the carrier between a projected operative position and a retracted release position; second resilient means acting between the carrier and the tongue urging the tongue in the operative direction, and manually operable overriding means for moving the tongue into a release position against the action of the second resilient means, whereby the bolt can be released without disturbing the frangible member.

Preferably, the carrier is adapted for rectilinear motion relatively to the supporting structure. The first resilient means may comprise a spring or springs, and preferably comprises one or more helical coil compression springs engaging between part of the supporting structure, and the carrier. It is also preferred that the second resilient means comprises a spring, and again this is preferably a helical coil compression spring engaging between the tongue and a part of the carrier.

According to a preferred feature of the invention, the overriding means preferably includes a rotary detent engageable with the tongue, or with a part movable with the tongue, only during movement of the tongue between the operative and release positions, but adapted to be disengaged, when the tongue is in the operative position. This is a significant feature of the invention, because it ensures that the overriding means cannot be left in a position where it holds the tongue in the operative locking position (a socalled dead-lock). If a dead-lock arrangement were used, then it would be possible to lock the bolt, so that it could not be released even in an emergency, and this would defeat the basic reason for using the bolt.

In the preferred construction, the overriding means comprises a key operated device, and preferably it takes the form of a tumbler or barrel lock, having a cam rotatable with the barrel, the cam providing the detent for engagement with the tongue. The support structure preferably comprises a casing which encloses the carrier, the frangible member, and the tongue.

In some instances, it may be desirable to provide a dead-locking device, which will normally hold the bolt in the locked position, until it is released either by breaking of the frangible member, or operation of the manually operable overriding means. For this purpose, there may be an articulated dead-locking device carried by the carrier and resiliently loaded into an active position where it prevents movement of the tongue relatively to the carrier, thereby automatically holding the tongue in the operative (locking) position, there being a stationary element in the path of movement of the dead-locking device and adapted to trip the dead-iocking device when the carrier moves into the release position.

Consequently, if the frangible member is broken, thus releasing the carrier, as the latter moves into its release position, it will trip the dead-locking device, permitting the tongue to move with the carrier into the release position. Otherwise, the tongue will remain in the locked position.

Preferably, the construction is such that the dead-locking device is prevented from returning to its active position until the carrier moves into the operative position. It will be appreciated therefore, that once the frangible member has been broken, it is not possible to re-set the dead-locking device, without inserting a fresh frangible member. In the preferred construction, the dead-locking device comprises a lever pivoted on the carrier, one end of the lever being engageable with the tongue and the other having an inclined face adapted to engage with and ride over the stationary element when the carrier moves towards the release position, the engagement of the lever with the stationary element during movement of the carrier towards the release position causing turning of the lever against its spring loading away from the active position.

Other preferred features of the invention will appear from the following description of door bolts constructed and adapted to operate in accordance with the invention, which are described by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is an internal view of a door bolt with one cover and a glass plate removed, and the bolt in the unlocked position, Figure 2 is a view similar to Figure 1, but showing the glass plate in position and the bolt unlocked manually, Figure 3 is a view similar to Figure 1, but showing another construction in which a deadlocking device is provided, Figure 4 is a view similar to Figure 3, but showing the position when the dead-lock is released and the glass plate removed, and Figure 5 shows a cover plate for use with a bolt constructed in accordance with Figures 1 and 2 or Figures 3 and 4.

The bolt which is illustrated in Figures 1 and 2, is adapted to be fitted into a door (not shown) although in some instances, it could be fitted into the jamb of a frame surrounding the door. The bolt has a metal casing 10 which is generally rectangular, and similar to the casing of a door lock. The casing 10 is provided with a front plate 12 which projects above and below the casing, and which is adapted to be aligned with the distal edge of a door, when the casing 10 is let into an opening formed in the door, in similar fashion to a door lock.

A pair of parallel, horizontal guide spindles 14 and 1 6 is secured within the casing 10, and a metal carrier 1 8 which is generally of the "E" shape illustrated, is mounted on the spindles. The spindles 14 and 1 6 pass respectively through bores 20 and 22 formed in the upper and lower arms of the carrier 1 8, whereby the latter is adapted for horizontal sliding motion on the spindles. A helical coil compression spring 24 is provided on each of the spindles 14 and 16, and each of these springs engages between the inside surface of the plate 12, and outer edge 26 of the carrier 1 8. Consequently, the compression springs 24 urge the carrier 1 8 inwardly, that is to the right as seen in the drawing.

A rectangular glass plate 1 5 (see Figure 2) is provided, and is adapted to be placed in the housing 10, so that its inner edge engages with the inner end plate 30 of the housing, and its outer edge engages with the inner edge 28 of the deep central portion 27 of the carrier 18. The width of the glass plate is such, that it can only be inserted by moving the carrier 1 8 outwardly (i.e. to the left as seen in the drawings) to the position shown in Figure 2, thereby compressing the springs 24.

Once the rectangular glass plate 15 has been fitted into this position, it will hold the carrier 1 8 in this outward position, which is hereinafter referred to as the operative position.

A projection 34 at the lower end of the carrier 1 8 is bored to receive a slidable stud 36, which is secured to the inner side of a tongue 38. A helical coil compression spring 40 surrounds the stud 36, and engages between the inside face of the tongue 38, and the outside face of the extension 34. Consequently, the spring 40 tends to hold the tongue 38 in an outer position relatively to the carrier 1 8 as shown in Figure 1, although the arrangement provides for possible relative motion of the tongue 38, in the same sense as the permitted motion of the carrier 1 8, but relatively to the carrier.

The tongue 38 is adapted to be projected through a slot 39 in the front plate 12 of the housing 10, and provides the element, which is engageable with a recess or strike-plate (not shown) in the door frame, whereby the door can be secured in a closed position. The arrangement is such, that when the carrier 1 8 is moved into the operative position, and held there by the glass plate, it forces the tongue 38 into the projected operative position, thereby locking the door.

There are two similar large rectangular holes 32 formed respectively one in each of the side plates of the housing 10, and corresponding openings are formed in the door itself, so that it is possible to obtain access to the glass plate 1 5 through the holes 32, from either side of the door.

It will be appreciated, that if the glass plate is broken, then the carrier will immediately move inwardly under its spring loading, to an inner or release position, taking the tongue 38 with it. The parts then occupy the position shown in Figure 1, and the door is unlocked. It will also be appreciated that the door could have an opening on one side only, in which case access to the glass plate could only be had from that side of the door.

Further, it will be understood that a lever having a knob could be provided on the outside of the bolt casing, the lever having a detent engageable with the glass plate, so that by striking the knob, the lever can be used to break the glass plate. Hence, with the arrangement described so far, it is possible to employ the bolt, to lock a door, and to provide means for emergency release of the bolt, by breaking of the glass plate. Clearly, when the carrier 1 8 is moved inwardly to the release position by its springs 24, this has the effect of taking the tongue 38 with it, into the retracted position illustrated.

A rod 42 is secured to the tongue 38 and extends inwardly therefrom, there being a notch 44 formed in the underside of the rod 42. A barrel lock 46 is fixed in the housing 10, so that it is accessible from one or both sides of the door, and the barrel 48 is attached to a cam 45 (see Figure 2) which provides a detent engageable with the notch 44. In the inoperative position of the lock 46, which is illustrated in Figure 1, the detent is out of engagement with the notch 44.

Supposing that the glass plate is fitted, and the carrier 1 8 holds the tongue 38 in the projected operative position shown in chain-dotted lines in Figure 2, so that the door is secured. If it is required to open the door, without disturbing the glass plate, it is possible to utilise the appropriate key, to turn the barrel 48, thereby causing the detent 45 to engage in the notch 44, and to move the rod 42 inwardly, carrying the tongue 38 with it to the unlocked position shown in full lines in Figure 2. During this motion, the spring 40 is compressed, but the carrier 1 8 remains immobile.

In this way, it is possible to move the tongue 38 into the release position without disturbing the glass plate. However, the detent 45 does not become disengaged from the rod 42, and as soon as the key is released, the spring 40 will return the tongue 38 to the locked position and the detent 45 will disengage from the rod 42.

It will be appreciated that a significant feature of the design shown in Figures 1 and 2 is that the glass plate 1 5 is divorced from direct action on the tongue 38, through the intervention of the resiliently loaded lost motion device provided by the extension 34 and the stud 36.

Referring now to Figures 3 and 4, there is shown another form of bolt, which in many respects is the same as that shown in Figures 1 and 2, but which is fitted with an additional deadlocking device. The bolt has a casing 50 which is adapted to fit in a door, and there is a front plate 52 on the casing. A pair of parallel horizontal guide spindles 54 and 56 is secured within the casing 10, and a metal carrier 58 which is generally of the "E" shape illustrated, is mounted on the spindles 54 and 56. These spindles pass respectively through bore 60 and 62 formed in the upper and lower arms of the carrier 58, whereby the latter is adapted for horizontal sliding motion of the spindles. A helical coil compression spring 64 is provided in each of the spindles 54 and 56, and in this construction, the inner end of each spring 64 is received in a counterbore 63 in the carrier 58.As with the previously described construction, the springs 64 urge the carrier 58 inwardly, that is to the right as seen in the drawings.

A rectangular glass plate, indicated by chaindotted lines 65 in Figure 3, is provided, and is adapted to be placed in the housing 50, so that its inner edge engages with the inner end plate 70 of the housing, and its outer edge engages with the inner edge 68 of the deep central portion 67 of the carrier 58. The width of the glass plate 65 is such, that it can only be inserted by moving the carrier 58 outwardly (i.e. to the left as seen in the drawings) to the position shown in Figure 3, thereby compressing the springs 64. Once the rectangular glass plate 65 has been fitted into this position, it will hold the carrier 58 in this outward operative position.

As with the previously described construction, there is a projection 74 at the lower end of the carrier 58, and this projection is bored to receive a slidable stud 76, which is secured to the inner side of a tongue 78. A helical coil compression spring 80 surrounds the stud 76, and engages between the inside face of the tongue 78, and the outside face of the extension 74. Consequently, the spring 80 tends to hold the tongue 78 in an outer position relatively to the carrier 58 as shown in Figure 3, although the arrangement provides for possible relative motion of the tongue 78, in the same sense as the permitted motion of the carrier 58, but relatively to the carrier.

The tongue 78 is adapted to be projected through a slot 79 in the front plate 52 of the housing 50, and provides the element, which is engageable with a recess or strike plate (not shown) in the door frame, whereby the door can be secured in a closed position. The arrangement is such, that when the carrier 58 is moved into the operative position, and held there by the glass plate 65, it forces the tongue 78 into the projected operative position, thereby locking the door. There are two similar large rectangular holes formed respectively one in each of the side plates of the housing 10 and aligned with the glass plate 65, and corresponding openings are formed in the door itself, so that it is possible to obtain access to the glass plate 65 through the holes, from either side of the door.As with the construction described with reference to Figure 1 and 2, it is possible of course, to have an opening only in one side of the door, so that access to the glass plate can be had only from that side, and it is also possible to provide a lever on the outside of the door, for breaking the glass. Hence, the arrangement described so far is almost identical with that shown in Figures 1 and 2, and it is possible to employ the bolt, to lock a door, and to provide means for emergency release of the bolt, by breaking the glass plate.

A rod 82 is secured to the tongue 78 and extends inwardly therefrom, there being a notch 84 formed in the underside of the rod 82. A barrel lock 86 is fixed in the housing 50, so that it is accessible from one of both sides of the door, and the barrel 88 is attached to a cam 85, which provides a detent engageable with a notch 84. In the inoperative position of the lock 86, which is illustrated in Figure 3, the detent is out of engagement with the notch 84. The lock 86 provides a manual overriding means for the bolt, which is adapted to operate in similar fashion to the manual overriding means described with reference to Figures 1 and 2. So long as the glass plate 65 remains in the position shown in Figure 3, the carrier 58 is held in the operative position, and the carrier will in turn, hold the tongue 78 in the operative (locked) position.Before considering the release of the bolt however, it is necessary to describe a dead-lock arrangement.

A dead-lock lever 90 is pivoted on the lower end of the projection 74 and a torsion spring 92 coiled around the pivot has arms engaging with the projection 74 and with the lever 90, so that this spring tends to turn the dead-lock lever 90 in a clockwise direction as seen in the drawings. The outer end of the dead-lock lever is square, but the inner end is rounded or inclined, at least on the underside. A turned-over part of the dead-lock lever at its inner end lies in the path of movement of the detent 85, and the inner end of the deadlock lever is engageable with a part of the casing of the tumbler lock 86, or an extension of that casing, which provides a stationary element in the casing 50.

When the glass plate 65 is in position, and the carrier 58 and tongue 78 are in their respective operative positions, the dead-lock lever is urged by the spring 92 into the horizontal position shown in Figure 3, where it engages with a stop 94. In this position, the outer end of the dead-lock lever engages behind the tongue 78, and because the outer end of the lever 90 is square, it is then impossible for the tongue 78 to be moved inwardly to the release position, because force applied through the tongue to the dead-lock lever exercises no turning moment on that lever.

Consequently, in this condition, the bolt is dead locked, and it is not possible to release the tongue 78, unless the glass plate 65 is broken. This deadlocked condition is sometimes required, to prevent unauthorised entry into a building.

Now if the glass plate 65 is broken, the springs 64 urge the carrier 58 inwardly to the release position. During this motion of the carrier, the inner rounded end of the dead-lock lever 90 rides over the curved upper portion of the lock 86, causing the lever 90 to turn in an anti-clockwise direction, against the action of its torsion spring 92. This motion disengages the outer end of the dead-lock lever 90 from the tongue 78, and the tongue is then able to move inwardly to the release position, carried by the carrier 58. It will be noted that there is an angular cut-out 96 in the tongue 78, and during the inward motion of the tongue, the inclined top surface of this cut-out 96 rides over the outer portion of the dead-lock lever 90.Thus, emergency release of the bolt is still provided for despite the dead-locking arrangement, because breaking of the glass plate 65 always allows the bolt to disengage its tongue 78 from the recess or strike plate of the door jamb.

Furthermore, once the glass plate has been broken, and the carrier 58 moved to the release position, it is not possible to re-engage the deadlocking lever 90, with the inner face of the bolt 78.

To enable re-engagement of the dead-locking lever, it is first necessary to fit a new glass plate forcing the carrier 58 to its operative position, so that the tongue 78 is also- moved to the operative position.

Supposing now that the tumblerlock 86 is operated as an override for the bolt, as described with reference to Figures 1 and 2, during the initial motion of the detent 65, it will engage with and turn the dead-locking lever 90 in an anti-clockwise direction, against the action of the spring 92, thereby tripping the dead-locking lever, so that the detent 85 can then engage in the notch 84, and move the rod 82 with the tongue 78 to the release position, despite the fact that the glass plate has not been broken.If this manual override of the bolt is used, then when the key in the lock 86 is released, the spring 80 returns the tongue 78 to its operative position, and the rod 82 becomes disengaged from the detent 85 as described in relation to the first arrangement, but in this instance, the torsion spring 92 is then able to turn the dead-locking lever 90 back into the horizontal position, illustrated in Figure 3, where once again the dead-locking effect is exercised on the tongue 78. Therefore, operation of the manual override provided by the tumbler lock 86, permits the dead-locking effect to be reinstated automatically, whereas this is not the case, if the glass plate 65 is broken.

In Figure 5, there is shown part of a door 100, in which a bolt of the kind illustrated in Figures 1 and 2 has been fitted. The bolt itself is not generally visible, but the tongue 38 is shown in the projected position, and the tumbler lock 46 is also visible. A metal or plastics cover plate 102 is secured to the outside of the door in the region of the bolt, the cover plate being formed with a large opening 104, through which the glass plate 1 5 is visible. An internal lip (not shown) surrounding the opening 104 engages with a part of the casing 10, to locate the cover 102 relatively to the casing. A projection 106 at the lower end of the plate 102 is cut away on the underside so that it provides a finger grip, which can be used as a handle for the door.

Claims (13)

1. A door bolt comprising a supporting structure; a carrier movable relatively to the supporting structure between an operative door locking position and a release position, there being first resilient means loading the carrier towards the release position; a frangible member located by the support structure in a manner such that it engages with the carrier, or with an element movable with the carrier, to hold the carrier against its resilient loading in the operative position, whereby the carrier is adapted to be released to move into the release position if the frangible member is broken; a tongue mounted on the carrier for movement in the same sense as, but relatively to the carrier, between a projected operative position and a retracted release position; second resilient means acting between the carrier and the tongue urging the tongue in the operative direction, and manually operable overriding means for moving the tongue into a release position against the action of the second resilient means, whereby the bolt can be released without disturbing the frangible member.

2. A door bolt as claimed in Claim 1, in which the carrier is adapted for rectilinear motion relatively to the supporting structure.

3. A door bolt as claimed in Claim 1 or Claim 2, in which the first resilient means comprises one or more helical coil compression springs engaging between part of the supporting structure and the carrier.

4. A door bolt as claimed in any one of Claims 1 to 3, in which the second resilient means comprises a helical coil compression spring engaging between the tongue and a part of the carrier.

5. A door bolt as claimed in any one of Claims 1 to 4, in which the overriding means includes a rotary detent engageable with the tongue, or with a part movable with the tongue, only when manually operated to move the tongue between the operative and release positions, but adapted to be automatically disengaged, when the tongue moves into the operative position.

6. A door bolt as claimed in Claim 5, in which the overriding means comprises a key-operated device.

7. A door bolt as claimed in Claim 6, in which the key-operated device is a tumbler or barrel lock having a cam rotatable with the barrel, the cam providing the detent for engagement with the tongue.

8. A door bolt as claimed in any one of Claims 1 to -7, in which the support structure comprises a casing which encloses the carrier, the frangible member-and the tongue.

9. A door bolt as claimed in any one of Claims 1 to 8, in which there is an articulated dead-locking device carried by the carrier and resiliently loaded into an active position where it prevents movement of the tongue relatively to the carrier, thereby automatically holding the tongue in the operative (locking ) position, there being a stationary element in the path of movement of the dead-locking device and adapted to trip the deadlocking device when the carrier moves into the release position.

10. A door bolt as claimed in Claim 9, in which the construction is such that the dead-locking device is prevented from returning to its active position until the carrier moves into the operative position.

11. A door bolt as claimed in Claim 9 or Claim 10, in which the dead-locking device comprises a lever pivoted on the carrier, one end of the lever being engageable with the tongue and the other having an inclined face adapted to engage with and ride over the stationary element when the carrier moves towards the release position, the engagement of the lever with the stationary element during movement of the carrier towards the release position causing turning of the lever against its spring loading away from the active position.

12. A door bolt constructed and arranged substantially as herein described with reference to Figure 1 and 2 of the accompanying drawings.

13. A door bolt constructed and arranged substantially as herein described with reference to Figures 3 and 4 of the accompanying drawings.