GB2323405A - Push bar latch release - Google Patents

Abstract

An actuator for e.g. emergency access doors, has a horizontally disposed push bar 15. Inward movement of the push bar causes release of the door latch or door bolts The actuator includes a lever 31 in the release mechanism, the moment arm of the lever reducing on relative inward movement of the push bar. This arrangement gives relatively high initial operating force followed by an increasing rate of release travel.

Description

DOOR EXIT DEVICE This invention relates to a door exit device, and particularly to a door latch mechanism for emergency exit doors of e.g. public buildings.

Many buildings have emergency exits which are normally locked against access from the outside but can be opened from the inside at will. Such exits are not used for normal entry and exit from a building, but are intended to provide an alternative escape route in the event of a fire or other emergency. The latch mechanism of the exit must be capable of being actuated in the dark, in smoke and in situations where panic or crushing of people has occurred; accordingly it is usual to provide a release bar which extends across the full width of the exit.

A typical prior latch mechanism comprises a generally horizontal release bar pivoted at its ends on a door about a horizontal axis and connected to bolts extending vertically into the floor and door frame. The bar is normally retained in an outward condition with the bolts engaged, but can be pivoted downwards and towards the door to withdraw the bolts and permit the door to be opened.

This mechanism is effective but it not aesthetically pleasing, and there is a tendency to use the release bar as e.g. a coat hanger, or to lean on the bar so that the door is opened accidentally. Both of these disadvantages are potentially serious since the first may jam the mechanism, and the second may cause a false alarm to be raised.

Furthermore the conventional kind of release bar is rather angular and has a tendency to snag clothing as people pass through the emergency exit. This in turn leads to obstruction and delay, and may result in injuries if a large number of people are attempting to exit the building.

Another kind of release mechanism comprises a sliding push bar which releases the door latch on the application of pressure. An inner 'U' shaped channel is fixed horizontally to a door by its base and houses a release mechanism. An outer 'U' shaped channel fits over the inner channel to enclose the mechanism and is spaced from the door by an amount sufficient to give the necessary release travel to the door latch. This mechanism can be aesthetically pleasing but has the serious disadvantage that a coin or like item may accidentally be dropped on the upper exposed edge of the inner channel and prevent -.e outer channel being pushed towards the door to release the door latch.

The consequences of a jammed latch are clearly most serious.

In one solution the outer 'U' shaped channel fits within an external channel fixed to the door, but this is not aesthetically pleasing.

A further disadvantage of the sliding kind of mechanism is that the end thereof presents a right angle which may snag clothing with the consequences mentioned above.

The present invention seeks to address these problems whilst providing an aesthetically pleasing design which will appeal to architects, can be produced at relatively low cost and can be customized to meet the purchasers requirements.

According to a first aspect of the invention there is provided a latch release device for a bolt of a hinged leaf of a door or window, the device comprising a body for attachment to the leaf, a cover for the body and a release mechanism for connection to a bolt and adapted for actuation by relative inward movement of said cover relative to said body, the release mechanism including a lever having a moment arm which reduces on said relative inward movement.

Preferably the lever arm includes a peg and slot connection, the peg moving along the slot to vary said moment arm. In the preferred embodiment the lever is pivoted to the body and has a first moment arm for connection to said bolt and a second moment arm having a slot for engagement by a peg of said cover. Preferably said first moment arm is substantially constant during said relative inward movement.

The body and cover may comprise respective generally 'U' shaped channels fitting within one another to define an enclosed longitudinal space for the release mechanism.

Preferably the cover fits over the body and is adapted to extend generally horizontally of said leaf. The cover and body may be directly biased apart by means of a spring.

Preferably the end of the device adjacent the hinged edge of said leaf is tapered away from the edge, and in a preferred embodiment the body and cover are tapered.

Inward movement of said cover relative to said body is preferably non perpendicular, thus giving increased travel for a given outward projection of the device and ensuring that the cover does not tilt relative to said body.

The generally horizontal outer face of the device is preferably tapered downwardly away from said body to prevent relative movement being obstructed by items resting on said outer face in use. In a preferred embodiment the cover is a close fit over the body, and the upper face of the body is at an angle sufficient to urge said items up the face of said leaf in use.

Other features of the invention will be apparent from the following description of a preferred embodiment, illustrated by way of example only in the accompanying drawings in which: Fig. 1 is an elevation of an emergency exit door; Fig. 2 is a front elevation of a release mechanism according to the present invention; Fig. 3a is a plan view of the mechanism of Fig. 2 in the passive condition; Fig. 3b is a plan view of the mechanism of Fig. 2 in the actuated condition; Fig. 4 is an enlarged section through the mechanism of Fig.2 illustrating the general disposition of the components; Fig. 5 is an enlarged partial longitudinal section through the mechanism of Fig. 5 illustrating the internal components in the passive condition; Fig. 6 is a side elevation of a yoke for the mechanism illustrated in Fig. 5.

Fig. 7 corresponds to Fig. 5 and illustrates the internal components in the actuated condition; and Fig. 8 is a scrap horizontal section illustrating an open emergency door and the release mechanism of this invent ion.

In the accompanying drawings, the clearances between some components and the relative sizes have been somewhat distorted in order to illustrate the invention with clarity; in practice such large clearances may not be required.

With reference to the drawings Fig. 1 shows an emergency door exit of a building. A door 11 is hinged to a frame 12 and has a generally horizontal release mechanism 13 connected to a conventional horizontal bolt and/or to conventional vertical bolts (not illustrated).

Figs. 2 and 3 illustrate a body channel 14 adapted to be fixed by e.g. screws through the base thereof to the door 11. A release member or touch bar 15, generally 'U' shaped in section, fits over the body channel 14 and is maintained at a distance from the door by an internal spring. A horizontal bolt 16 is adapted to engage a keeper in the door frame 12.

As will be explained in detail below, the touch bar 15 can be pushed inward relative to the body channel and thereby cause an internal lever arrangement to withdraw the bolt 16, thus allowing the door to be pushed open to the outside.

Fig. 3b illustrates the touch bar 15 in the inner condition in which the bolt 16 is withdrawn. The internal mechanism constrains the touch bar 15 to move at an angle to the face of the door, in the direction of arrow A, for reasons which will become apparent.

The hinge end of the mechanism 13 is tapered so as not to present an obstruction when the door is in the opened condition. As illustrated in Fig. 8, the tapered end does not present a snag to clothing of persons pressing against the mechanism as they leave in the direction of arrow B. A rounded end to the touch bar 15 will serve just as well, the important aspect being that an edge or projection is avoided. By constraining movement in the direction of arrow A, the projection of the touch bar is minimised and thus rapid exit of people is facilitated. Furthermore the travel of the touch bar is increased for a given perpendicular movement, and this is useful in obtaining the necessary travel of the bolt without excessive projection of the touch bar.

The components of the release mechanism are typically folded or punched from sheet steel, or may in part be aluminum extrusions. Figs. 4 and 5 illustrate a preferred embodiment. The pivot connections are omitted from Fig. 4 for reasons of clarity.

A body channel 14 has a base 22 and opposed upstanding arms 23,24. The base is intended to be secured to a door, for example by screws passing through holes formed at convenient intervals. A touch bar 15 is also 'U' shaped and has opposite arms 25,26 that fit around the outside of the body channel 14, as best illustrated in Fig. 4. The arms 23,24 are angled outwardly adjacent the base 22, as illustrated, in order to provide a smooth transition from the free edges of the body channel to the surface of the door. This anti-jamming feature is further described below.

The body channel 14 and touch bar 15 extend over the full length of the mechanism.

Fig. 5 illustrates a portion of the mechanism and is a somewhat schematic sectional view on line 5-5 of Fig. 4.

A support channel 27 is fixed centrally within the body channel 14 and has opposite upstanding arms 28,29.

Each arm 28,29 has a somewhat triangular lever 31 pivoted thereto about an axis 32. The levers 31 are identical and disposed between respective arms 28,29 and 23,24. The pivot may be provided by for example a single round steel rod passing through suitable holes drilled in the levers 31 and the arms 28,29, and retained by the arms 23,24, by circlips or in any other suitable manner.

The support channel 27 has a cut-out 34 at the rear thereof to allow a second round steel rod 33 to pass through apertures at the base apex of the levers 31. The rod 33 may be retained by the arms 23,24, by circlips or in any other suitable manner.

A diagonal slot 35 is formed in the arms 28,29 extending downwardly (as viewed) from the corner opposite the pivot axis towards the centre thereof. The levers 31 each have a slot 36 extending from the third apex towards the pivot axis 32 (generally horizontally as viewed in Fig.

5).

The touch bar 15 has an internal 'U' shaped channel 41 fixed to the centre thereof with opposite arms 42,43. A single round steel rod 44 extends through opposite apertures in the arms 42,43 and through the slots 35 and 36. The rod is again retained between arms 23,24 by circlips, simple abutment or in any other manner.

A slave arm 45 (Fig. 6) is retained for movement with levers 31 by rod 33 which passes through yoke arms 46,47.

The arm 45 passes through support channel 27 and is connected in any convenient manner to the latch bolt 16, for example by a nut and bolt through aperture 48.

A spring (not illustrated) urges the body channel 14 and touch bar 15 apart. A hairpin spring located around pivot axis 32 and having opposed arms bearing on the inner side of the base of the body channel and the underside of the push bar is suitable.

The components illustrated in Fig. 5 are intended for location at the end of the release mechanism adjacent the bolt 16. However the precise location is not important since the slave arm 45 can easily be manufactured to the desired length. In order to ensure parallel motion of the push bar 14, a second set of channels 27,41 and levers 31 may be provided at the end of the mechanism adjacent the door hinges; these can be identical to the arrangement already described, or may be somewhat simplified since a link for the slave arm 45 is not required. The levers 31 may for example be omitted entirely leaving the slot 35 to guide the channel 41 and hence the push bar in the desired direction. A second return spring is desirable.

The angled slot 35 is particularly advantageous since it ensures that pressure on the touch bar 15 always results in parallel inward movement and consequent actuation of the levers 31. If the slots 35 were perpendicular to the door there would be a danger that pressure applied to the touch bar at the end adjacent the door hinges might cause tilting of the touch bar about the levers 31 rather than pivoting of the levers and consequent movement of the bolt 16.

In operation, the touch bar 15 is urged towards the door against the effect of the return spring. The pin 44 and slot 35 constrain the touch bar to move at an angle in the direction of arrow A (Fig. 3b). As a consequence the levers are pivoted from the position illustrated in Fig. 5 to the position illustrated in Fig. 7, the slot 36 permitting movement of the pin 44 towards the pivot axis 32.

Pivoting of the levers 31 causes the pin 33 to move to the right as viewed, and as a consequence the slave arm 45 which is connected to the bolt 16. Thus pressure on the touch bar 15 causes the bolt 16 to withdraw, and allows the door to open from within.

As the levers 31 pivot from the passive (clockwise) condition to the activated condition, the pivot pin 44 moves closer to the pivot axis 32. Thus initial movement of the levers 31 is at a high lever ratio and the initial pulling force exerted by slave arm 45 is also high; this is advantageous since the high initial force can be useful in overcoming initial friction and resistance to movement of the bolt (which may not have been actuated for some time).

The lever ratio reduces as the levers 31 approach the end of their travel; this reduces the pulling force on the slave arm 45 but increases the rate of travel for a given angular movement of the lever. As a consequence the inward movement of the push bar 15 can be reduced for a given travel of the bolt 16, and the outward protrusion of the release mechanism from the door can be minimised.

As is clear from Figs. 5 and 7, movement of the pivot pin 33 is at a substantially constant radius from axis 32, and the pin 33 moves 'over centre' so as to maintain the slave arm 45 at a substantially constant distance from the base of the support channel 27.

Fig. 6 illustrates an optional slot 49 to receive the pivot pin 33. A bias spring urges the bolt 16 outwardly of the release mechanism; this is represented schematically by a light tension spring 50. During actuation by the push bar 15, the spring 50 maintains the pin 33 at the right hand end of the slot (as viewed) and exerts a small additional load as the bolt is withdrawn. If the door is slammed shut, the bolt 16 is urged inwardly by the corresponding door frame keeper (not illustrated), and the slot permits the slave arm 45 to move to the right (as viewed) without disturbing the pin 33 and thus the levers 31. The light spring 50 urges the bolt into its keeper when the door is closed in the frame. A simple round hole can alternatively be provided for the pin 33 and a lost motion linkage provided elsewhere in the mechanism in a known manner.

As mentioned in the introduction, a problem with earlier kinds of sliding mechanism is that a coin or similar object may lay on the upper surface of the mechanism in the recess between the touch bar 15 and the door, and thus jam, the mechanism. The angled surfaces 23,24 of the body channel of the present invention are angled away from the door, as illustrated in Fig. 4, the effect being that any object, such as a coin, lying on the upper exposed limb will be pushed up the face of the door as the touch bar moves inwardly. Various profiles are possible, especially with extruded sections, and the angle can be chosen to suit particular circumstances. Both sides of the body channel preferably have the same angled face (as illustrated) in order to ensure that the channel is not handed - this in turn ensures that the release mechanism can be fitted either way up, thus allowing a single assembly to be used for both left and right hinged doors.

The flat outer face of the touch bar can be customised by the application of printing, embossing or decorative motifs without adversely affecting function of the mechanism.

Claims (12)

CLAIMS:

1. A latch release device for a bolt of a hinged leaf of a door or window, the device comprising a body for attachment to the leaf, a cover for the body and a release mechanism for connection to a bolt and adapted for actuation by inward movement of said cover relative to said body, the release mechanism including a lever having a moment arm which reduces on said relative inward movement.

2. A release device according to claim 1 wherein said lever arm includes a peg and slot connection, the peg moving along the slot to vary said moment arm.

3. A release device according to claim 1 or claim 2 wherein the lever is pivoted to the body and has a first moment arm for connection to said bolt and a second moment arm having a slot for engagement by a peg of said cover, said second moment arm reducing on said relative movement.

4. A release device according to claim 3 wherein said first moment arm is substantially constant during said relative inward movement.

5. A release device according to any preceding claim wherein said body and cover comprise respective generally 'U' shaped channels fitting within one another to define an enclosed longitudinal space for said release mechanism.

6. A release device according to claim 5 wherein the cover fits over the body and is adapted to extend generally horizontally of said leaf, in use.

7. A release device according to any preceding claim wherein the cover and body are biased apart by means of a spring.

8. A release device according to any preceding claim wherein the end of the device adjacent the hinged edge of said leaf in use, is tapered away from said edge.

9. A release device according to any preceding claim wherein inward movement of said cover relative to said body is non perpendicular.

10. A release device according to any preceding claim wherein the generally horizontal outer face of the device is, in use, tapered downwardly away from said body to prevent relative movement being obstructed by items resting on said outer face.

11. A release device according to any preceding claim wherein said cover is a close fit over said body, the upper face of the body, in use, being at an angle sufficient to urge items up the face of said leaf on said relative inward movement.

12. A relative device substantially as described herein with reference to the accompanying drawings.