GB2283271A

GB2283271A - Emergency cover plate

Info

Publication number: GB2283271A
Application number: GB9320735A
Authority: GB
Inventors: Peter Cash
Original assignee: Pickersgill-Kaye Ltd; Pickersgill Kaye Ltd
Current assignee: Pickersgill-Kaye Ltd; Pickersgill Kaye Ltd
Priority date: 1993-10-08
Filing date: 1993-10-08
Publication date: 1995-05-03
Anticipated expiration: 2013-10-08
Also published as: GB9320735D0; GB2283271B

Abstract

An emergency cover plate 1 is provided having a main body 1 and a mounting portion 3 by which it may be mounted in a frame 10, the mounting portion being connected to the main body 1 by a weakened section 4. The cover plate is adapted to be mounted in a frame 10 such that pressure on the cover plate causes the cover plate to break at the weakened section 4 allowing the cover plate to be expelled from the frame 10, without fracturing the main body 1. The invention finds particular use in fire alarms, emergency stop alarms or release mechanisms in vehicles. <IMAGE>

Description

EMERGENCY COVER PLATE The invention relates to an emergency cover plate, in particular for use in fire alarms or in emergency stop alarms or release mechanisms in vehicles.

In situations where emergency action is to be initiated, for example by setting of an alarm, or triggering an emergency door release button on a train, it is essential that the alarm activation means should be easily accessible and easy to activate but not to the extent that inadvertent triggering is possible.

In known manually operated fire alarm systems a trigger is mounted within a box in a prominent position, and triggering may only occur by breaking a breakable panel. Panels made of glass are generally scored or otherwise weakened in an attempt to cause the glass to break in a predicted manner. This reduces the risk of injury from broken glass, but is not always reliable. Alternative materials have been used, for example sugar glass, by which the risk of direct injury has been reduced. However, there have been suggestions that sugar glass in the powdered form (such as is produced on fracture) has toxic properties, rendering it unsuitable for safety applications.

Emergency release mechanisms for releasing vehicle doors, particularly doors opened and closed by hydraulic systems, are required adjacent each door, but must be protected from mis-use or accidental triggering by passengers. Attempts to prevent this have involved mounting such buttons behind glass plates, but as with fire alarms, there is concern about the safety of the plates when broken.

An aim of the present invention is therefore to provide a cover plate for a variety of emergency applications through which an alarm trigger or emergency release mechanism may be safely and easily accessed, while being resistant to mis-use or accidental activation.

According to one aspect of the present invention there is provided an emergency cover plate comprising a main body and a mounting portion connected thereto by a weakened section so that the main body of the cover plate is adapted to break away from its mounting at the weakened section.

The invention is further directed to an emergency cover device having a cover plate and a frame, wherein the cover plate comprises a main body and a mounting portion connected thereto by a weakened section and wherein the mounting portion of the cover plate is held in the frame so that pressure on the cover plate causes the mounting portion to break off and the cover plate to be released from the frame.

Advantageously, the weakened section is a tab formed as a continuation of the cover plate and which has a reduced thickness compared to the main body of the cover plate and/or has scoring or other weakening features to cause it to break in a predicted manner.

The tab is adapted to fit into a slot provided in the frame and abuts against a pressure plate so that pushing the cover plate against the pressure plate causes the tab to break off.

In an advantageous arrangement in accordance with the invention it is envisaged that the weakened section of the cover plate is provided as an area in the edge region of the cover plate and is weakened by means of scoring or cutting. When assembled into a frame the weakened section lies between outer and inner projections provided in the frame the inner projection acting as the pressure plate so that pressure on the cover plate against the inner projection causes the weakened section to break enabling it to pass over the outer projection.

In a further advantageous arrangement, the cover plate is resiliently mounted against the frame, for example by the use of a spring mechanism so that on breaking the weakened section, the cover plate is expelled forcibly from the frame.

It is envisaged that for ease of assembly the weakened section is located asymmetrically in the cover plate and that the interacting parts of the frame are located accordingly.

The invention may be constructed in a number of ways, but one specific example will now be described by way of example with reference to the accompanying drawings, in which: Figure 1A is a schematic view of the cover plate of an embodiment of the invention; Figure 1B is a view of the cover plate in the direction of the arrow X in Fig. 1A Figure 2A is a view of the frame from behind with the position of the cover plate when assembled shown in dotted lines.

Figure 2B is a cross section of the frame through line Y-Y and in the direction of the arrow Y in Fig. 2A showing the position of the tab and the pressure plate when assembled.

Figure 3A is a view from the front of the pressure plate against which the weakened section abuts, Figure 3B is a view of the pressure plate in the direction of the arrow Z in Fig. 3A.

Figures 1A and 1B illustrates the construction of the cover plate 1 from the front. This essentially comprises a plate made of a lightweight, strong} transpdrent plastics material, for example an acrylic plastics material such as PMMA. The plate is formed with an upper lip 2 which is insertable under the top edge of the frame 10 (Fig. 2A). The lateral dimensions of the cover plate 1 are such that the lateral edges lie flush with the sides of the frame and do not retain the cover plate 1 in the frame 10 in any way. The lower edge of the cover plate 1 has a tab 3 which forms a weak point in the construction of the cover plate 1. The tab 3 is machined so as to be considerably thinner than the remainder of the cover plate 1, for example half as thick. The front surface of the cover plate 1 and the tab 3 is consistent while at the rear, there is a step between the two sections of a depth dependent on the respective thicknesses of the main body of the cover plate 1 and the tab 3. To further weaken the tab 3, the join of the tab 3 and the main body of the cover plate 1 is provided with a score 4. Cut out portions 5 and 6 also serve to weaken the connection between the main body of the cover plate 1 and the tab 3.

In Figure 1B, a side view of the cover plate 1 is shown which illustrates the relative thicknesses of the main body of the cover plate 1 and the tab 3. In an example of the cover plate constructed from PERSPEX, the thickness of the cover plate will optimally be 3.00mm and the thickness of the projection 1.50mm, to within say 10%.

Figure 2A shows the frame 10 from behind. A cut out area 11 is provided in which the cover plate 1 sits, the upper lip 2 of the cover plate 1 fitting behind upper section 12 of the frame 10 (see dotted lines). The emergency actuator is located in the cut out area 11 behind the cover plate. First and second recesses 13 and 14 are cut into the back of the lower section 15 of the frame 10, second recess 14 being cut into part of the first recess 13 so as to form a stepped configuration.

Figure 2B illustrates a cross-section of the frame 10 through the line Y-Y, and shows the position in the assembled state of the tab 3 and the pressure plate 2.

The second recess is adapted to receive the tab 3 of the cover plate 1 which is clamped into position between the pressure plate 20 and the lower section 15 of the frame.

Figs. 3A and 3B show views of the pressure plate 20. Pressure plate 20 is mounted in recess 14 of the frame 10 so as to retain the tab 3 of the cover plate 1 in recess 13. Pressure plate 20 is constructed in a stepped manner with a central raised section 21. In the assembled state of the cover plate and the frame 10, the raised section 21 of the pressure plate 20 abuts against the tab 3 so that the upper edge 22 of raised section 21 coincides with the weakened, scored edge of tab 3. The cover plate is held firmly in that position by means of a projection 23 provided on the surface of raised section 21 which mates with a hole 7 provided in the rear surface of the tab 3.

Once assembled, the cover plate 1, frame 10 and pressure plate 20 are mounted over an emergency door release mechanism, alarm, or any other emergency device so that the cover plate 1 prevents access to and initiation of the emergency procedure. To gain access to the emergency device, the main body of the cover plate 1 is struck firmly, causing a shearing force to be exerted on the projection 3 at its weak point i.e.

along its scored edge 4. The body of the cover plate 1 is pressed inwards beyond the pressure plate 20 resulting in the breaking off of the projection 3 along the edge 4 and allowing the cover plate 1 to be released through the cut-out portion 11 of the frame 10. Access to the underlying emergency device is thereby achieved.

In one advantageous arrangement the assembly is also provided with a spring device (not shown) mounted behind the cover plate 1 (position 8 in Fig. la). This serves two purposes in that it braces the cover plate 1 firmly against frame 10 and prevents noise through vibration, and it also aids the expulsion of the cover plate 1 from the frame 10 when the projection 3 is broken off. Preferably this spring is arranged behind the lower third of the cover plate 1.

It is envisaged that the invention, although described with particular reference to emergency release mechanisms and alarms, may be used in many different applications where a once-only breaking of a seal is required. Furthermore, the invention has been described with a breakable projection while it is envisaged that other configurations might be equally suitable while still falling within the scope of the present invention.

Claims

Claims:

1. A cover plate comprising a main body and a mounting portion connected thereto by a weakened section so that the main body of the cover plate is adapted to break away from the mounting at the weakened section.

2. A cover plate according to claim 1 in which the mounting portion is a tab formed as a continuation of the main body of the cover plate.

3. A cover plate according to claim 1 or 2 in which the weakened section has a cross-section of reduced thickness compared to the main body of the cover plate.

4. A cover plate according to any one of claims 1 to 3 in which the mounting portion is of reduced thickness compared to the main body of the cover plate.

5. A cover plate according to any preceding claim in which the outer surfaces of the main body and the mounting portion are continuous and in which a step is formed between the inner surfaces of the main body and the mounting portion.

6. A cover plate according to any preceding claim, made of a transparent material.

7. A cover plate according any preceding claim in which the weakened section includes scoring of the connection between the main body and the mounting portion.

8. An emergency device including a cover plate according to any one of claims 1 to 7 and a frame, wherein the cover plate is held in the frame by the mounting portion so that pressure on the cover plate causes the mounting portion to break and the cover plate to be released from the frame.

9. An emergency device according to claim 8 in which the frame includes outer and inner securing sections between which the mounting portion is adapted to be held.

10. An emergency device according to claim 9 in which the inner securing section acts as a pressure point such that pressure applied to the cover plate against the inner securing section causes the mounting portion to break at the weakened section.

11. An emergency device according to any one of claims 8 to 10 in which the cover plate is resiliently mounted against the frame so that on breaking at the weakened section the cover plate is expelled from the frame.

12. An emergency device according to claim 11 in which a spring means constitutes the resilient mounting.

13. An emergency device according to any one of claims 8 to 12 in which the mounting portion is provided asymmetrically on the cover plate so that the cover plate may be mounted in the frame in only one orientation.

14. An emergency device substantially as described herein with reference to any of the accompanying Figures 1 to 3B.