GB2126766A

GB2126766A - Structural element for the construction of burglar proof rooms or receptacles

Info

Publication number: GB2126766A
Application number: GB08319511A
Authority: GB
Inventors: Werner Messerli; Theodor Schiff; Eric Wyttenbach
Original assignee: Securiton AG
Current assignee: Securiton AG
Priority date: 1982-07-22
Filing date: 1983-07-19
Publication date: 1984-03-28
Also published as: AT395917B; FR2530847B1; IT1198650B; IT8309480A0; GB8319511D0; DE3227397A1; DE3227397C2; ATA230483A; IT8309480A1; FR2530847A1; CH659533A5; GB2126766B

Abstract

The structural element comprises a gas-tight envelope formed of at least one plastics film (1) and provided with an opening for producing a positive or a negative pressure in the envelope, stiffening means (2) being disposed in the latter. Furthermore, a pressure- dependent electric switch (4, 5, 8) is mounted in the envelope in such a way that upon a change in pressure brought about by a leak or by damage to the envelope, the switch is actuated and sets off an alarm. The structural element is economical, easy to assemble, and cannot be sabotaged. <IMAGE>

Description

SPECIFICATION Structural element for the construction of burglar-proof rooms or receptacles This invention relates to the construction of burglar-proof rooms or receptacles, and more particularly to structural elements used in such construction, of the type having a gas-tight envelope of plastics with at least one opening for producing pressure above or below atmospheric pressure in the envelope and with stiffening means disposed in the envelope.

French published patent application No.

7632494 describes a jacketing for producing burglar-proof rooms consisting of structural elements formed of two gas-tight plastics plates which are separated from one another by stiffening means and welded together hermetically at the circumference. Positive or negative pressure is produced in these structural elements, and they are mounted on the walls of a strongroom, for instance, air-tightly connected to one another, and connected to a component sensitive to variations in pressure, disposed within the strongroom. Any attempt to damage the enclosure thus formed, causing a variation in pressure, sets of an alarm.

These prior art structural elements used for burglar-proofing have the drawback, however, that between them, as well as between them and the component sensitive to pressure variations, which component is situated outside of the structural elements themselves, it is necessary to provide air-tight, pneumatic connections, which can be sabotaged. The pressure-sensitive component is expensive and, because it is separate from the structural elements, incurs additional installation expense. Furthermore, with a component which is sensitive to pressure variations but is disposed away from the structural elements, the response time in the event of a burglary attempt tends to be longer.

Thus, there is a need for structural elements for the construction of burglar-proof rooms or receptacles which fulfill their purpose better than the prior art structural elements and ensure that an alarm is reliably set off. Such structural elements should also be low-priced, easy to assemble, proof against sabotage, and quick to respond.

According to the present invention, there is provided a structural element of the type initially mentioned, wherein the envelope is formed of at least one flexible plastics film, and an electric, pressure-dependent switch is mounted in the envelope in such a way that it is actuated upon a change in pressure brought about by a leak in or damage to the envelope.

Two emboidments of the invention will now be described in detail, but way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a structural element in a first embodiment of the invention, Figure 2 is a detail of the structural element of Figure 1, in section, and on a larger scale, Figure 3 is a partial section through a structural element in a second embodiment of the invention, and Figures 4 and 5 are diagrams of different possibilities for electrically connecting the structural element according to the invention to an alarm device (not shown).

Figure 1 shows a plastics film 1 comprising two layers of polyethylene with a layer of aluminium between them. The layers of polyethylene have high mechanical strength, while the layer of aluminium is gas-tight. The film 1 is folded together and gas-tightly welded together at the ends so that it forms a gas-tight envelope. The envelope may be formed of two films welded together at the edges instead. In the envelope is an insert of porous material 2, e.g. cardboard. The cardboard must be at least 0.5 mm thick. Also disposed in the envelope are two flexible diaphragms 4 of nylon. Cemented to the surface of the porous material 2 facing the diaphragms 4 is a copper strip 5. The attachment 3 of the diaphragms 4 is shown in detail in Figure 2.A nipple 10 of brass bears the diaphragm 4 which is secured to the envelope 1 by means of a washer 11 of nylon, two washers 12, 14 of metal, and a nut 1 5. Between the washers 12 and 14 there is a soldering tab 7. The two nipples 10 are connected by means of a hose 6. It is possible however, to close each nipple 10 separately, in which case the connection 6 is not necessary.

Negative pressure is produced in the envelope by means of a pump via one on the nipples 10 until one end of each nipple 10 comes in contact 8 with the copper strip 5 owing to the bending of the flexible diaphragms 4. The insert of porous material 2 prevents the plastics film from sticking together after the air has been exhausted. Any leak in the envelope and any damage thereto causes an immediate rise in pressure and hence the opening of the pressure-dependent electric switch comprising the two contact locations 8.

Because this switch has two contact locations 8, it affords high switching reliability. Furthermore, the switch can easily be connected by means of the soldering tabs 7.

Figure 3 is a section through part of a structural element according to a second embodiment which differs from the first embodiment principally in that positive pressure is produced in the envelope.

Corresponding components in the two embodiments have the same reference numerals, only one contact location 8 of the switch being shown in Figure 3. This embodiment differs structurally from that of Figure 1 in that the copper strip 5 is cemented to the surface of the porous material 2 remote from the diaphragms 4, and the nipple 10 is somewhat longer. Two holes 1 6 are provided in the cardboard 2 for the passage of the nipples 1 0.

Any leak in the envelope 1 and any damage thereto cause an immediate drop in pressure and hence the opening of the pressure-dependent electric switch comprising the two contact locations 8.

In Figure 4, the switches 25-29 of the structural elements 20-24 are connected in series, and the output of the switches 26, 29 is connected to an alarm device (not shown).

In Figure 5, each switch 25-29 of the structural elements 29-24 is separately connected to an alarm device (not shown), so that in case of an alarm, it can immediately be ascertained which structural element is defective.

Surfaces which are as smooth as possible are particularly suitable for mounting the self-adhering structural elements according to the invention.

The film 1 is very resistant but must not be exposed to friction with any objects. It is further to be heeded that the non-affixed surfaces of the envelope of each mounted structural element are free in order to ensure that the film lifts off the porous material 2. The electric switch is protected from dust by the envelope without any additional housing.

The structural element according to the invention can be used for the protection of receptacles or rooms, e.g. of alarm-system cabinets, strongrooms, safes, data-storage cabinets, data-processing rooms, motor vehicles, and the like.

Claims

1. A structural element for the construction of burglar-proof rooms or receptacles, having a gastight envelope of plastics with at least one opening for producing pressure above or below atmospheric pressure in the envelope and with stiffening means disposed in the envelope, wherein the envelope is formed of at least one flexible plastics film, and an electric, pressuredependent switch is mounted in the envelope in such a way that it is actuated upon a change in pressure brought about by a leak in or damage to the envelope.

2. A structural element in accordance with claim 1, wherein the stiffening means are formed of porous material, the area of which is substantially equal to the area of the envelope, and the thickness of which is at least 0.5 mm.

3. A structural element in accordance with claim 2, wherein the porous material consists of a piece of cardboard.

4. A structural element in accordance with claim 1 , wherein the plastics film comprises two layers of polyethylene between which a layer of aluminium is disposed.

5. A structural element in accordance with claim 2, wherein the electric, pressure-dependent switch comprises two diaphragms of flexible plastics, each diaphragm being mounted on a nipple of brass, one end of which forms a contact part of the switch, wherein a contact strip of copper is cemented to the surface of the porous material facing the diaphragms, and wherein the whole is designed in such a way that when there is negative pressure in the envelope, the switch is closed at the contact locations formed by the said end of each nipple and the contact strip, and upon an increase in pressure the switch opens.

6. A structural element in accordance with claim 2, wherein the electric, pressure-dependent switch comprises two diaphragms of flexible plastics, each diaphragm being mounted on a nipple of brass, one end of which forms a contact part of the switch, wherein a contact strip of copper is cemented to the surface of the porous material remote from the diaphragms, and wherein the whole is designed in such a way that when there is positive pressure in the envelope, the contact is closed at the contact locations formed by the said end of each nipple and the contact strip, and upon a drop in pressure the switch opens.

7. A structural element in accordance with claim 5 or 6, wherein the diaphragms are of nylon, and a soldering tab means of which the switch is connectible is mounted on each nipple.

8. A structural element in accordance with claim 5 or 6, wherein the nipples are pneumatically connected to one another by means of a hose.

9. A structural element in accordance with claim 5 or 6, wherein each nipple is separately closed.

10. An assembly of structural elements in accordance with claim 1, wherein the structural elements are separated from one another pneumaticaily.

11. An assembly of structural elements in accordance with claim 10, wherein the switch of each structural element is separately connected to an alarm device.

12. An assembly of structural elements in accordance with claim 10, wherein the switches of the structural elements are electrically connected in series.

1 3. A structural element for the construction of burglar-proof rooms or receptacles, substantially as hereinbefore described with reference to the accompanying drawings.

14. An assembly of structural elements for the construction of burglar-proof rooms or receptacles, substantially as hereinbefore described with reference to the accompanying drawings.

1 5. An alarm system for protecting rooms or receptacles against burglary attempts, comprising structural elements substantially as hereinbefore described with reference to the accompanying drawings.