Fire alarm system

• US 4,884,222 A
• Filed: 07/29/1985
• Issued: 11/28/1989
• Est. Priority Date: 07/31/1984
• Status: Expired due to Fees

• Current Assignee: Hochiki Corporation
• Original Assignee: Hochiki Corporation
• Inventors: Matsushita, Eiji, Nagashima, Tetsuya, Kitajima, Akira, Yuchi, Sadataka
• Primary Examiner(s): Lall, P. S.
• Assistant Examiner(s): Black, Thomas G.
• Application Number:
  US06/760,312
• Time in Patent Office: 1,583 Days
• Field of Search: 364/550, 364/557, 364/555, 364/554, 364/185, 340/577, 340/588, 340/589, 340/584, 340/628
• US Class Current: 340/506
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence

Abstract

A fire alarm system of the present invention is adapted to compute an approximation equation based on the detection data from a detector or detectors such about a smoke density, a temperature, a gas concentration, etc. and predictively determine a fire based on the approximation equation. The system including computing section for computing an approximation equation approximating a change in the physical phenomenon related to the occurrence of a fire which is output from the detector or detectors, sequentially sampled and stored and for computing a future value of the phenomenon estimated from the approximation by using a predetermined number of the data stored in a storing section. The future vale is compared with a data value preliminarily set in association with the fire alarming and an alarm is generated when the relation therebetween is not within a predetermined range.

Claims

1. A fire alarm system which comprises:

one or more detecting sections for detecting a change in the physical phenomen of the surroundings related to the occurrence of a fire and outputting analog data corresponding to the change;

a data sampling section for sampling the data from each of the detecting sections at periodic intervals;

a storing section for storing the data output from the data sampling section for each of;

said detecting sections;

a computing section for sequentially extracting the data from said storing section, computing from such data an approximation equation of said change, and computing a future value of said phenomen predicted from said approximation equation by using a predetermined number of the data stored in said storing section;

a comparing section for comparing said future value predicted by said computing section with a preliminarily set data value related to fire alarming and generating an output when the relation therebetween is not within a predetermined range; and

an alarming section for generating an alarm in response to the output from said comparing section.

2. A fire alarm system according to claim 1, wherein the plurality of detecting sections are sampled sequentially to derive data therefrom and said storing section stores said data at addresses assigned to the respective detecting sections.

3. A fire alarm system which comprises:

one or more detecting sections for detecting a change in the physical phenomena of the surroundings related to occurrence of a fire and outputting analog data corresponding to said change;

a data sampling section for sampling the data from each of said detecting sections at periodic intervals;

a storing section for storing the data output from said data sampling section for each of said detecting sections;

a computing section for sequentially extracting the data from said storing section;

computing a linear, quadratic or higher order approximation equation of said change; and

computing a preestimated time at which a future value of said phenomena as predicted from said approximation equation will exceed a predetermined value, such computation being carried out by using a predetermined number of the data stored in said storing section;

a comparing section for comparing said preestimated time with a predetermined time interval and generating an output when the preestimated time is shorter than such predetermined time interval; and

an alarming section for generating an alarm in response to the output from said comparing section.

4. A fire alarm system as claimed in claim 3, wherein said computing section carries out the computation of said preestimated time based on the values of the difference between the detection data at each sampling interval and the detection data at each preceding sampling interval.

5. A fire alarm system as claimed in claim 4, wherein said computing section compares, said difference value with a first and a second threshold level, outputs a cancelling signal for cancelling the detection data when said difference value is lower than the first threshold level, outputs a fire alarm signal when said difference value is above the second threshold level, and carries out a second computation, by a functional approximation method, when said difference value is higher than the first threshold level but lower than the second threshold level.

6. A fire alarm system as claimed in claim 3, wherein said computing section carries out the computation and preestimation based on a regression line obtained from the plural sampling date by approximation.

7. A fire alarm system as claimed in claim 3, wherein said computing section carries out the computation and preestimation based on a regression curve obtained from the plural sampling date by approximation.

8. A fire alarm system as claimed in claim 3, in which the computing section computes and preestimates from the detection data of plural kinds of physical phenomena which are caused to change by a fire, the times required for such phenomena to reach predetermined danger levels, and when such times are shorter than preset times for escape the comparing section generates an output to said alarming system to cause it to generate an alarm.

9. A fire alarm system as claimed in claim 8, further comprising a logical determining circuit for establishing said predetermined danger levels and a further fire danger level such that irrespective of said computation and preestimation, when the detection data exceeds said fire danger level the computing section generates an output to said alarming section to cause it to generate an alarm.

10. A fire alarm system as claimed in claim 3 wherein said computing circuit section is adapted to compare the periodically sampled detection data with a computation-initiating level so as to initiate the computation and preestimation only when said detection data exceed said computation-initiating level.

11. A fire alarm system according to claim 3 wherein said computing section comprises:

a first level comparing section for generating an output signal when said output data from said data sampling section exceeds a predetermined computation initiating level;

a running average computing section for extracting a predetermined number of data from said storing section by the output from said first level comparing section and computing running averages;

a running average storing section for sequentially storing the computation results of said running average computing section; and

a second level comparing section for outputting a signal for actuating said first computing section when said computation results of said running average computing section exceeds a predetermined level;

said first computing section being adapted to compute a regression line based on a predetermined number of running averages, and to determine said predetermined time on the basis of such regression line.

12. A fire alarm system according to claim 11, wherein said first level comparing section generates an output when a predetermined number of output data from said data sampling section successively exceed the predetermined computation initiating level.

13. A fire alarm system according to claim 11, wherein said second level comparing section comprises a difference computing section for computing differences between a plurality of computed running averages by said running average computing section and a difference comparing section for outputting a signal for actuating said first computing section when said computed differences exceed a predetermined value.

14. A fire alarm system according to claim 13, wherein said first level comparing section generates an output when a predetermined number of output data from said data sampling section successively exceed the predetermined computation initiating level.

15. A fire alarm system which comprises:

one or more detecting sections for detecting a change in the physical phenomena of the surroundings related to the occurrence of a fire and outputting analog data corresponding to the change;

a data sampling section for sampling the data from each of said detecting sections at periodic intervals;

a storing section for storing the data output from said data sampling section for each of said detecting sections; and

a computing section for sequentially extracting the data from said storing section;

computing a linear, quadratic or higher order approximation equation of said change; and

computing a future value of said phenomena after a predetermined time has passed, such computation being carried out by use of a regression line determined from a predetermined number of the data stored in said storing section;

a comparing section for comparing said future values of said phenomena with predetermined values thereof and generating an output when any of such future values exceeds the corresponding predetermined value; and

an alarming section for generating an alarm in response to the output from said comparing section.

16. A fire alarm system as claimed in claim 15, wherein said computing section carries out the computation and preestimation based on a regression line obtained from the plural sampling data by approximation.

17. A fire alarm system as claimed in claim 15, wherein said computing section derives a difference value from the detection data and compares it with a first and second threshold level;

outputs a cancelling signal for cancelling the detection data when the difference value is lower than the first threshold level;

outputs a fire alarm signal when the difference value is above the second threshold level; and

carries out a second computation, by the functional apprximation method, when the difference value is higher than the first threshold level but lower than the second threshold level.

18. A fire alarm system according to claim 15, which further comprises a level determining section provided between said storing section and said first computing section for outputting a signal for actuating said computing section when the output data from said data sampling section exceeds a predetermined computation initiating level.

19. A fire alarm system according to claim 15, wherein said computing section comprises:

a first comparing section for generating an output signal when the output data from said data sampling section exceeds the predetermined computation initiating level;

a running average computing section for extracting a predetermined number of data from said storing section by the output from said first comparing section and computing running averages;

a running average storing section for sequentially storing the computation result of said running average computing section; and

a level comparing section for outputting a signal for actuating said first computing section when computation result of said running average computing section exceeds the predetermined level;

said first computing section being adapted to compute regression lines based on a predetermined number of running averages, and to determine said predetermined time on the basis of said regression lines.

20. A fire alarm system according to claim 19, wherein said first level comparing section generates an output signal when a predetermined number of output data from said data sampling section successively exceed the predetermined computation initiating level.

21. A fire alarm system according to claim 19, wherein said second level comparing section comprises a difference computing section for computing differences between a plurality of running averages computed by said running average computing section and a difference comparing section for outputting a signal for actuating said first computing section when the computed differences exceed a predetermined value.

22. A fire alarm system according to claim 21, wherein said first level comparing section generates an output signal when a predetermined number of output signal from said data sampling section successively exceed the predetermined computation initiating level.