WO2004066237A1

WO2004066237A1 - Fire alarm

Info

Publication number: WO2004066237A1
Application number: PCT/GB2004/000124
Authority: WO
Inventors: Diana Burlington
Original assignee: Diana Burlington
Priority date: 2003-01-18
Filing date: 2004-01-15
Publication date: 2004-08-05
Also published as: GB2397422A; GB0301213D0; EP1590778A1

Abstract

A portable warning device comprising a generally circular moulded plastics housing (10) which is provided with a main vent (12) for allowing the ingress of air from the outer surroundings into the housing for testing. A water detecting probe (22) is attached to the device via a flexible lead which is wound on a spool (24) in the housing. When in use, the user unwinds the lead from the spool (24) so that the water detecting probe (22) hangs down below the device. A rate of rise of temperature detector (100 - Figure 4), carbon monoxide detector (200 - Figure 4) and microprocessor (300 - Figure 4) which registers an output from various detectors and sounds an alarm (SPK1 - Figure 4), are housed within the housing (10). In use, air from the surrounding area enters the housing (10) through the main vent(12) and/or an optional secondary vent (36) where it can be tested by the carbon monoxide detector (200), and the rate of rise of temperature detector (100). If either of those detectors registers it detection variable at a level greater than some predetermined threshold the alarm is sounded to alert the user of potential danger. The water detecting probe (22) is arranged to sound the alarm in the event that it comes into contact with water, to indicate flooding. The device may also include an LPG detector which is detachable from the device and mountable at a lower position relative thereto, which causes the alarm to sound in the event that LPG is detected.

Description

Fire Alarm

This invention relates to a fire alarm and, more particularly but not necessarily, to a personal portable fire alarm for detection of a fire in its vicinity, and including means to alert the user accordingly.

It is well known to provide smoke detectors and/or carbon monoxide detectors in buildings such as residential accommodation, hotels, etc. to detect smoke and/or carbon monoxide in the air and sound an alarm in the event that such substances are detected. This type of device may be supplied by batteries and/or wired into the building's main power supply, and is usually mounted in a suitable location within the building.

However, although a person may have the protection of a smoke or carbon monoxide detector in separate units within their home, a traveller would need to rely on the facilities provided in their chosen temporary accommodation, which may not always be reliable and, in some cases, may not be available at all. US Patent Number 4321591 describes aportable, battery-powered multiple warning device including a smoke detector, a gas detector, an alarm clock and/or burglar alarm contained within a single unit which can be easily carried by a user and which includes an audible alarm which is activated in the event that smoke or gas is detected so as to alert the user.

There are two types of conventional smoke detector currently in common use. One such smoke detector comprises a light emitter and detector arranged within a housing having apertures therein. Under normal circumstances, the detector receives light from the emitter at some maximum intensity. In the event of a fire, smoke enters the housing and smoke particles in the light path between the emitter and the detector cause the intensity of light reaching the detector to be reduced or infra-red light from the source is scattered by smoke particles and this scattered light is detected by an infra-red detector. In response to the reduced light intensity or the detection of scattered light, an alarm is triggered. However, this type of smoke detector is not particularly suitable for use as a portable fire alarm because of the risk of contamination: it will be appreciated that a portable alarm is likely to be carried around in a user's luggage or pocket such that dust and fabric particles, and the like, may enter the alarm housing and interrupt the light path, thereby causing false alarms to be triggered and reducing the overall effectiveness of the device. Another known type of smoke detector employs a radioactive material to detect smoke. However, the use of radioactive material in a portable alarm is obviously undesirable and may be dangerous, particularly in the event that the device becomes damaged.

It is also known to employ a carbon monoxide detector as a fire alarm. Smouldering fires usually give off carbon monoxide gas which, when detected in quantities exceeding some predetermined threshold, cause an alarm to be triggered. However, such detectors tend not to be particularly effective in detecting fires having pockets of intense heat.

We have now devised an improved arrangement. In accordance with the present invention, there is provided a fire alarm, comprising means for detecting one or more combustion gases, particularly but not necessarily exclusively carbon monoxide, in the vicinity of said fire alarm, means for detecting a rise in temperature in the vicinity of said fire alarm, and means for causing an alarm to be triggered in response to detection of one or more said combustion gases and in response to detection of a rise in said temperature.

The means for detecting the presence of one or more combustion gases preferably comprises a carbon monoxide detector which may be arranged to test the air either continuously or periodically at a predetermined rate. The means for causing an alarm to be triggered is then beneficially set to detect that the quantity of detected carbon monoxide exceeds some predetermined threshold, say 30 parts per million or less. The sensitivity of the alarm is set so as to ensure that it is suitable for detecting fire, but an additional advantage is, of course, that it will also detect the presence of carbon monoxide caused by faulty appliances and the like, as the quantity of carbon monoxide given off under such circumstances is significantly higher than the threshold level required to detect fire.

The means for causing an alarm to be triggered preferably also includes a rate of rise in temperature detector, such that in the event that a rise in temperature is detected in the vicinity of the alarm, the alarm will be triggered only if the rate of rise in temperature exceeds some predetermined threshold level.

Thus, the present invention provides a fire alarm which is suitable for detecting smouldering fires and fires having pockets of intense heat equally effectively, and which is safe and robust. Accordingly, the fire alarm of the present invention may be provided as a portable unit. The provision of a rate of rise of temperature detector to detect the presence of a fire has the advantage of being lower in cost than conventional smoke detection means, results in easier assembly of the unit in view of the lack of additional components and mouldings, and the elimination of the requirement for careful alignment of opto devices. Such a detector is also very sensitive, and may be designed to detect, for example, a 2°C per minute rise in temperature and it is also relatively easy to make such means water/moisture proof by, for example, covering the circuit board embodying such means with conformal coating lacquer, which is a big advantage when the user is, for example, boarding or camping in a wet environment.

The alarm may also include means for detecting the presence and/or level of liquid in the vicinity thereof, and means for causing an alarm to be triggered in the event that the level of liquid in the vicinity of the alarm exceeds some predetermined level, thereby alerting the user that there is a flood. In one embodiment of the invention, means may be provided to hang or otherwise mount the alarm unit at some height within an area, so that the alarm will be triggered in the event that liquid is detected at that height. The liquid detector preferably tests its surroundings continuously.

In one embodiment of the invention, a water level detector is removably connected to the main body of the alarm unit by, for example, a thin flexible lead, so that the water detector can be hung at or close to ground level with the rest of the device remaining well above ground level. Means may be provided for winding the lead around the removable section of the device to tidy it away. The alarm means may comprise an audible sounder and/or a vibrating mechanism. The device may be arranged to activate a different alarm in response to different types of danger. The alarm may comprise a piezo electric sounder disc, which may be fitted into a resonant cavity provided in the device housing, or more preferably it may comprise an electromagnetic sounder, which tends to be smaller than its piezo electric counterpart.

The device may incorporate other types of detector and/or alarm, such as a personal attack alarm for activation by the user in the event that they are in danger, detecting means (e.g. PIR) for detecting movement or heat in the vicinity of the device for early detection of predators, rodents and/or intruders. The device may also include means for detecting LPG (propane gas) for use, in particular, in boats, yachts, caravans, etc. Means are preferably provided to mount such LPG detection means low relative to the rest of the device because LPG is heavier than air.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a portable warning device according to an exemplary embodiment of the present invention;

Figure 2 is a front view of the device of Figure 1;

Figure 3 is a side cross-sectional view of the device of Figure 1; and

Figure 4 is a circuit diagram representing an exemplary implementation of a warning device according to an embodiment of the present invention.

Referring to Figures 1 to 3 of the drawings, a portable warning device according to an exemplary embodiment of the present invention comprises a generally circular moulded plastics housing 10. The housing 10 is provided with a main vent 12 for allowing the ingress of air from the outer surroundings into the housing for testing. A cavity 14 contains the batteries 16 to supply power to the device, the cavity 14 being provided with a cover 32, which can be removed by rotating it relative to the housing 10. The batteries 16 contact terminal 34 in the cavity 14 for connection to a printed circuit board (PCB) carrying the electrical circuit (see Figure 4), and a strap 18 is attached to the housing 10 via a loop 20 at the top for hanging the device at a convenient height in the user's accommodation. The overlapping portion between the housing 10 and the cover 32, provides a lip 34 to retain the strap 18.

A water detecting probe 22 is attached to the device via a flexible lead which is wound on a spool 24 in the housing. When in use, the user unwinds the lead from the spool 24 so that the water detecting probe 22 hangs down below the device (although the detecting probe 22 still works even if the lead is wound on the spool 24). The device may also have socket 26 for connecting another type of detector device, if required.

A rate of rise of temperature detector (100 - see Figure 4), carbon monoxide detector (200 - see Figure 4) and microprocessor (300 - see Figure 4) which registers an output from various detectors and sounds an alarm (SPK1 - see Figure 4), are housed within the housing 10. The carbon monoxide detector (200 - see Figure 4) may comprise an electrochemical CO sensor including a substance which reacts with carbon monoxide and a number of electrodes, typically a mixture of active transition metals bound to the surface of a PTEE membrane so as to have a very high surface area. The metals act as a catalyst to speed up any chemical reaction while remaining unchanged themselves. The carbon monoxide detector and alarm means are preferably arranged to trigger the alarm in the event that the quantity of CO detected exceeds some predetermined threshold value, say around 30ppm or less.

The device further comprises a switch 28 for turning the device on and off. One or more LED's 30 may be provided to indicate that the device is switched on. The or one of the LED's may be arranged to change colour or otherwise indicate that the battery power is low.

In use, air from the surrounding area enters the housing 10 through the main vent 12 (and/or an optional secondary vent 36) where it can be tested by the carbon monoxide detector 200, and the rate of rise of temperature detector 100. If either of those detectors registers it detection variable at a level greater than some predetermined threshold the alarm is sounded to alert the user of potential danger. The water detecting probe 22 is arranged to sound the alarm in the event that it comes into contact with water, to indicate flooding. The device may also include an LPG detector which is detachable from the device and mountable at a lower position relative thereto, which causes the alarm to sound in the event that LPG is detected.

An embodiment of the present invention has been described above by way of example only, and it will be apparent to a person skilled in the art that modifications and variations can be made to the described embodiment without departing from the scope of the invention.

Claims

CLAIMS:

1. A fire alarm, comprising means for detecting one or more combustion gases in the vicinity of said fire alarm, means for detecting a rise in temperature in the vicinity of said fire alarm, and means for causing an alarm to be triggered in response to detection of one or more said combustion gases and in response to detection of a rise in said temperature.

2. A fire alarm according to claim 1 , wherein said means for detecting the presence of one or more combustion gases comprises a carbon monoxide detector.

3. A fire alarm according to claim 2, wherein said carbon monoxide detector is arranged to test the air either continuously or periodically at a predetermined rate.

4. A fire alarm according to claim 2 or claim 3, wherein said means for causing an alarm to be triggered is set to detect that the quantity of detected carbon monoxide exceeds some predetermined threshold, for example, 30 parts per million or less.

5. A fire alarm according to any one of the preceding claims, wherein the means for causing an alarm to be triggered includes a rate of rise in temperature detector, such that in the event that a rise in temperature is detected in the vicinity of the alarm, the alarm will be triggered only if the rate of rise in temperature exceeds some predetermined threshold level.

6. An alarm according to any one of the preceding claims, including means for detecting the presence and/or level of liquid in the vicinity thereof, and means for causing an alarm to be triggered in the event that the level of liquid in the vicinity of the alarm exceeds some predetermined level.

7. An alarm according to claim 6 including means for mounting an otherwise hanging the alarm at some height within an area, so that the alarm will be triggered in the event that liquid is detected at that height.

8. An alarm according to any one of the preceding claims, comprising a water level detector removably connected to the main body of the alarm unit by, for example, a thin flexible lead, so that the water detector can be hung at or close to ground level with the rest of the device remaining well above ground level.

9. An alarm according to claim 8, including means for winding the lead around the removable section of the device.

10. A fire alarm according to any one of the preceding claims, comprising an audible sounder and/or a vibrating mechanism.

11. A fire alarm according to any one of the preceding claims, arranged to activate a different alarm in response to different types of danger.

12. A fire alarm according to any one of the preceding claims, wherein said alarm means comprises a piezo electric sounder disc, fitted into a resonant cavity provided in the device housing and/or wherein said alarm means comprises an electromagnetic sounder.

13. An alarm according to any one of the preceding claims, incorporating one or more of a personal attack alarm for activation by the user in the event that they are in danger, detecting means (e.g. PIR) for detecting movement or heat in the vicinity of the device for early detection of predators, rodents and/or intruders, and means for detecting LPG (propane gas).

14. An alarm according to claim 13, including means for mounting said LPG detection means low relative to the rest of the device.

15. An alarm substantially as herein described with reference to the accompanying drawings.