GB2252190A

GB2252190A - Fire alarm device

Info

Publication number: GB2252190A
Application number: GB9200959A
Authority: GB
Inventors: Shigeru Ohtani; Hiromitsu Ishii; Takashi Ono
Original assignee: Hochiki Corp
Current assignee: Hochiki Corp
Priority date: 1991-01-18
Filing date: 1992-01-17
Publication date: 1992-07-29
Anticipated expiration: 2012-01-17
Also published as: JP2889382B2; GB9200959D0; CH689497A5; JPH04330596A; FI916181A0; GB2252190B; AU1002292A; FI916181A; AU650939B2; DE4200947A1; FI107414B

Abstract

A fire alarm device for measuring the physical quantities of parameters arising from the outbreak of a fire and giving a fire alarm, in which membership functions showing the correlation between measured physical quantities and the danger degree which a person would actually feel with respect to the physical quantities are preset, the danger degree with respect to the physical quantities detected by a fire detection means being obtained by using the membership functions. An alarm in accordance with the danger degree is then given. The fire alarm device is thus capable of judging the outbreak of a fire based on an actual fire situation and giving an alarm in accordance with the degree of danger which a person would actually feel with respect to the scale, situation and so on of the fire. <IMAGE>

Description

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DESCRIPTION

FIRE'ALARM DEVICE The present invention relates to a fire alarm device for measuring physical quantities such as heat, smoke and so on arising from the outbreak of a fire and reporting the fire.

In a typical known fire alarm devicer a smoke sensor and a heat sensor are set in every surveillance area, and absolute values or change values of the physical quantities of substances (heat, smoke and so on) arising from a fire are detected by these sensors so as to detect the outbreak of the fire. In other words, it is determined that a fire has occurred by comparing data obtained from the sensors with a preset threshold value.

However, in such a conventional fire alarm device, measured values detected by the heat sensor and the smoke sensor show the quantities of heat and smoke accumulated in the surveillance area. Therefore, these values do not directly reflect the scale and so on of the origin of the fire.

Thus, the detection result of the conventional fire alarm device does not clearly indicate whether measured values are obtained from a large-scale fire, or whether the quantity of accumulated heat is large though the scale of the fire is not so large. Therefore, the scale and situation of a fire origin as criteria for judging the outbreak of the fire are not fixed, and thus it is impossible to give an alarm based on an actual fire situation.

while a fire alarm device is already known from our international Application PCT/JP90/00062 (designated states: AT,AU,DE,F1,GB,US), which calculates the scale of a fire origin and carries out a fire determination by it, if a person actually encounters a fire in practice, he/she empirically judges the degree of danger associated with the fire and takes action depending upon the degree of danger. Accordingly, the contents of an alarm should ideally be related to the degree of danger in consideration of the means for escape.

An object of the present invention is to provide a fire alarm device capable of judging a fire based on how an actual fire situation is perceived and giving an alarm depending upon the degree of danger which a person would actually feel with respect to the scalet situation and so on of the fire.

In order to achieve the above object, a fire alarm device in accordance with the present invention comprises a detection means for detecting one or more physical quantities which increase with the outbreak of a fire, such as changes in temperature, smoke density, generated gas density and atmospheric pressure, and a danger degree calculating means for enabling membership functions to be preset representative of the correlation between the arising value per unit time, such as heat release rate, smoke generation rate and gas value calculated by the quantities and the degree of danger which a person would feel with regard to such value, and for calculating the degree of danger with regard to the physical quantities by using the membership functions so as to give an alarm in accordance with the degree of danger.

The invention also includes a fire alarm device having a detection means for detecting one or more physical quantities arising from the outbreak of the fire and outputting analog data and a danger degree calculating means for enabling membership functions to be preset representative of the correlation between -3the analog value outputted by detecting said one or more physical quantities and the danger degree which a person would feel with respect to said analog value and calculating the danger degree with respect to said analog value outputted by said detection means by adopting said membership functions.

According to a fire alarm device having such construction, since the outbreak of a fire is judged and the danger of degree is obtained by using the membership functions, a result equivalent to the judgment of the person can be obtained. Therefore, it is possible to give a highprecision and proper fire alarm.

Furthermore, such a fire alarm device is effective in reducing false alarms.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:- Fig.1 is a structural view of one embodiment of a fire alarm device according to the present invention; Fig.2 is an explanatory view showing an example of a membership function concerning the heat release rate to be set in a danger degree calculating portion of the device; and Fig.3 is an explanatory view showing an example of a membership function concerning the smoke generation rate to be set in the danger degree calculating portion of the device.

The construction of the illustrated embodiment of fire alarm device will be first explained with reference to Fig.l. Detectors la to ln, such as heat sensors and smoke sensors, detect as analog values the physical quantities of parameters, such v i -4as heat temperature, smoke density and gas density, increasing with the outbreak of a fire. One detector or a plurality of detectors are placed in every surveillance area.

Output signals of the detectors la to 1n are timesequentially supplied to a danger degree calculating portion 3 through a transmission line 2 by sequentially scanning the detectors la to 1n in a predetermined cycle.

The danger degree calculating portion 3 contains membership functions showing the correlation between the arising value per unit time, such as heat release rate, smoke generation rate and gas value calculated by the physical quantities increasing with the outbreak of a fire and the danger degree which a person would f eel with regard to the physical quantities, or data corresponding to the membership functions, in the shape of a lookup table. The danger degree calculating portion 3 calculates data on the danger degree based on signal values transferred from the detectors la to ln according to the membership functions and the like, and transfers the data to a fire judging portion 4. The membership functions are obtained by making many subjects experience combustion states on the assumption of various kinds of fires, and converting the degree of danger with regard to the combustion states felt by the subjects into numerical values or functions by statistical processing.

The danger judging portion 4 compares a plurality of preset threshold values with the data on the danger degree supplied from the danger degree calculating portion 3, and judges the outbreak of a fire based on the relation between the threshold values and the data. If it is judged that the fire has occurred, the danger judging portion 4 determines the kind of an alarm, and transfers a corresponding alarm:o signal to various kinds of alarm devices and fire prevention devices through an alarm output portion 5.

4 k Fig. 2 illustrates a membership function expressing the degree of danger which a subject would feel with respect to the heat release rate of an inflammable article when a fire occurs. In other words, the horizontal axis indicates the heat release rate Qf [kW] of an inflammable article which corresponds to the scale of the fire, and the vertical axis indicates the degree to which the subject would feel danger with regard to the heat release rate (danger degree Df). Assuming that the danger degree of a state where all subjects feel danger is 1.0, the membership function of the danger degree is formed by statistically processing the ratio of the subjects who feel danger when the heat release rate Qf is less than that of the above state.

Membership functions which are thus obtained empirically or data corresponding to the functions are preset in the danger degree calculating portion 3. The danger degree calculating portion 3 finds a heat release rate Qf based on a signal transferred from the heat sensor of the detectors la to 1n, calculates a danger degree Df based on the heat release rate Qf, and outputs the danger degree Df to the fire judging portion 4.

On the other hand, Fig. 3 shows a membership function concerning the smoke generation rate obtained in the same manner as Fig. 2. The danger degree is determined based on the quantity of smoke by presetting the membership function concerning the smoke generation rate Qs shown in Fig. 3 in the danger degree calculating portion 3. In other words, the membership function shown in Fig. 3 is obtained by converting the ratio Ds of a plurality of subjects who would feel danger with regard to the smoke generation rate Qs [g/s] when, for example, a "kotatsu" (inflammable article A) and a 'Itatamill (inflammable article B) are burnt, into numerical values.

The danger degree calculating portion 3 finds a smoke generation rate Qs based on a signal representing the smoke 1 A density transferred from the smoke sensor of the detectors la to ln in the same manner as in the case of the heat release rate, and outputs a danger degree Ds corresponding to the smoke generation rate Qs.

When the data representing the danger degree output from the danger degree calculating portion 3 is supplied to the fire judging portion 4, it is compared with threshold values preset in the fire judging portion 4. Alarm data in accordance with the comparison result is output from a plurality of preset data. For example, in Fig. 2 or 3, if both of the danger degrees Df and Ds are less than 0.5, it is judged that an incipient fire has occurred, a pre-alarm is given to a guardroom to broadcast a message for escape. On the other hand, if both the danger degrees Df and Ds are more than 0.5, it is judged that the fire has been enlarged, all alarm devices in the building are made to give alarms, and a control operation is performed to operate fire preventing equipment, such as a fire door.

The level of the danger degree to give pre and main alarms can be changed depending upon the use condition of the room.

According to the embodiment described above, since the outbreak of a fire is detected and the danger degree is obtained by using the membership functions, the judgement result equivalent to the judgment of a person with regard to the fire can be obtained, and a high-precision and proper fire alarm can be output.

The above judgement process of the fire judging portion 4 is given as an example. Therefore, it is possible to process the danger degree Df obtained based on the membership function concerning the heat release rate and the danger degree Ds obtained based on the membership function concerning the smoke generation rate under a compound condition. Furthermore, various processes can be conducted, for example, one of the danger degree Qf or Qs has priority over the other in order to judge the fire situation and so on.

Although the membership functions concerning the heat release rate and the smoke generation rate of the physical quantities are formed and the danger degree is output according to the membership functions in the above embodiment, other physical quantities, for example, a change in atmospheric pressure or the like may be used. In addition, it is also possible to form a membership function with respect to analog outputs from the detectors so as to output the danger degree.

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Claims

1. A fire alarm device for judging the outbreak of a fire and giving an alarm, comprising:

detection means for detecting one or more physical quantities arising from the outbreak of the fire; danger degree calculating means for enabling membership functions to be preset representative of the correlation between the arising value per unit time, such as heat release rate, smoke generation rate and gas value calculated by said physical quantities and the danger degree which a person would feel with respect to said arising value, and for calculating the danger degree with respect to said arising value by comparing said physical quantities detected by said detection means with said membership functions; and fire judging means for determining an appropriate alarm depending upon said danger degree.

2. A fire alarm device for judging the outbreak of a fire and giving an alarm, comprising:

detection means for detecting one or more physical quantities arising from the outbreak of the fire and outputting analog data; danger degree calculating means for enabling membership functions to be preset representative of the correlation between the analog value outputted by detecting said one or more physical quantities and the danger degree which a person would feel with respect to said analog value, and for calculating the danger degree with respect to said analog value outputted by said detection means by comparison with said membership functions; and fire judging means for determining an appropriate alarm depending upon said danger degree.

3. A fire alarm device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.