KR900008377B1 - Dual spectrum fire sensor with discrimination - Google Patents

Abstract

A sensor system responsive to a fire or explosion comprises: a first control signal means for generating a first control signal when the first detector detects electromagnetic energy within a first spectral band having an amplitude greater than a first predetermined level; a second control signal means responsive to a second radiant energy detector; a third control signal means responsive to the first and second radiant energy detectors; a fourth control signal means for generating a fourth control signal; and an output gate means for generating an output signal only when the first, second and fourth control signals are all simultaneously gemerated.

Description

Dual spectrum fire detector with identification function

1 is a schematic diagram showing a three-channel detector system according to a first embodiment of the present invention.

2 is a timing diagram illustrating the operation of the detector system of FIG.

3 is a schematic diagram showing a three channel detector system according to a second embodiment of the present invention.

4 is a timing chart showing the operation of the detector system of FIG.

* Explanation of symbols for main parts of the drawings

10: 3-channel detector system 63 and 70: rise time detection circuit

15 photon detector 75 variable delay circuit

20: thermal detector 80: double time constant circuit

25, 30, 35 and 40: amplifiers 85 and 86: switches

45 and 50: threshold circuit 90: switch driver

60: comparator-critical circuit 95: dual threshold circuit

The present invention relates to the field of devices for detecting the presence of undesirable fires or explosions in protected areas or compartments, and then releasing fire extinguishing products to extinguish the fire.

More specifically, the present invention relates to a device for releasing fire extinguishing only when detecting a fire, for example by identifying a fire from a flash generated by a projectile penetrating a wall of a protected area.

There are many cases where areas or compartments must be protected from fire to protect human life. For example, flight crew, passenger cabin and engines are areas where fires could soon cause disasters. However, fire extinguishers loaded on airplanes increase weight to reduce performance and, in general, are loaded with only the amount of extinguishing fire required to extinguish the expected fire. The timing of the evolution is important. If released too soon, the extinguishant is consumed before it is really needed, and if released too late, it is not suitable for extinguishing fire.

Military vehicles, such as airplanes, tanks and troop transport vehicles, are susceptible to fire caused by the penetration of projectiles or shells. As projectiles or shell debris penetrate the compartment walls, radiant energy flashes in the ultraviolet, visible, and infrared spectral regions are created. Prior art fire detectors, based on their individual capabilities, can be flashed even if the fire detector judges the flash to be a fire and releases the extinguishing fire before the fire actually occurs, or if the fire detector determines that only the flash is generated and no fire is generated. Only one of these functions, which continues to exist, does not release the extinguishing product by only one of the functions of quickly determining the occurrence of fire (in the technical term, "detector" means a radiation sensing element that converts electromagnetic radiation into an electrical signal). do.

The term "sensor" refers to a system that uses at least one "detector" including other electronic devices by amplifying or processing the "detector" signal).

The fire detector system described in US Pat. No. 4,206,454 to Shapira et al. Can not only detect a fire, but also react to evolve by judging the glare generated by projectile penetration. Projectile flashes radiate into fast rising long-wave components and slow-rising short-wave components that enable the evolutionary product to operate as soon as the long-wave component passes the critical level. However, this operation becomes unnecessary if no fire occurs by projectile penetration, or too soon if the fire ignition is delayed, such as when the leaking fuel is subsequently ignited.

The fire detector system described in Bright's U.S. Patent No. 4,220,857 is equally unreasonable because it judges the projectile flash as a fire. When colliding, the projectile releases or explodes a small amount of small peat material, producing a large amount of carbon dioxide as the product of combustion, even if combustion continues for a short time and does not produce a slow hydrocarbon flame.

Bright's system responds to situations where the non-planckian emission of carbon dioxide molecules at 4.4 micrometers (example) exceeds the planckian emission at adjacent wavelengths, resulting in a fire output signal. do. Therefore, evolution is released to evolve flashes and explosions that will soon disappear with regulation.

The fire detector system described in US Pat. No. 4,101,767 to Lennington et al. Makes it difficult to distinguish flash from fire. The Lennington system is basically a single channel fire detector (using detector 30) with identification circuits (detectors 10 and 20) to prevent output while the color temperature is greater than some value (e.g. -2400K.). The detector system is specially designed to operate in an attack against armored vehicles. In this case, the long wavelength signal (4.4 micrometers) falls below the detector dark field value following a thermal thermal collision before the short wavelength detector displays a color temperature less than the preset value.

However, in airplane applications, this is rare, and the Lennington system can release evolution in order to extinguish the flash that will disappear on its own.

It is a primary object of the present invention to overcome the above mentioned disadvantages of the prior art fire detectors and to provide a new and improved fire detector which is operable to detect the presence of a fire and to release a fire extinguishing product.

It is also an object of the present invention to provide a new and improved fire detector capable of distinguishing a fire from abrupt flash radiation and the radiation energy resulting from the fire to be determined as a continuous flash by the detector system after the flash has occurred. will be.

To overcome these drawbacks of the prior art and at the same time achieve these objects of the present invention, the present invention electrically simulates what can occur optically in the event of a flash without subsequent fire. The timing of a fire extinguishing product may not be too early at times so that false alarms are generated (i.e. the extinguishing agent is released when a flash appears but there is no fire), but it should not be too late for the extinguishing agent to be unsuitable for extinguishing the fire.

The present invention is capable of detecting electromagnetic energy within a first predetermined critical spectral band and generating a first control signal proportional to the amplitude of the detected energy, and a first detector for generating electromagnetic energy within a second predetermined critical spectral band. A first detector capable of detecting and generating a first control signal proportional to the amplitude of the detected energy, and electromagnetic energy within a second predetermined critical spectral band, capable of detecting and proportional to the amplitude of the detected energy A three channel detector system having a second detector capable of generating a first control signal is provided.

The first channel of the detector system responds to the first detector and generates a third control signal whenever the first control signal exceeds a first predetermined threshold level. The second channel of the detector system responds to the second detector and generates a fourth control signal whenever the second control signal exceeds a second predetermined threshold level. The second channel of the detector system responds to the second detector and generates a fourth control signal whenever the second control signal exceeds a second predetermined threshold level. The third channel of the detector system is responsive to the first and second control signals and generates a fifth control signal until the difference in amplitude of the first and second control signals exceeds a third predetermined threshold level. If the third level is exceeded, the third channel prevents generating the fifth control signal for a period referred to as the "delay period". After the delay period, the third channel will again generate a fifth control signal. The first, second and third channels are electrically supplied to an output circuit which generates an output signal only when the third, fourth and fifth signals are simultaneously received from the first, second and third channels, respectively. When an output signal is generated, the output signal can be processed or used to operate the electromechanical fire extinguishing device.

The length of the delay period can be determined in various ways by other types of delay circuits combined with the third channel. The type of delay circuit used depends on the type of fire or explosion that can be expected to occur within the monitoring area. The simple form of the delay circuit merely prevents the fifth control signal from occurring during the predetermined period after the difference between the first and second control signals exceeds the third predetermined level.

Hereinafter, with reference to the accompanying drawings will be described in more detail the present invention.

In FIG. 1, the three channel detector system 10 includes a photon detector 15 that responds to radiant energy within a spectral band of relatively short wavelength (e.g., 0.7 to 1.2 microns or 0.1 to 2.0 microns), and a relatively long wavelength (e.g., For example, it has a heat detector 20 which responds to a spectral band of 7 to 30 microns or 5 to 30 microns). The analog output of each detector 15 and 20 is amplified by amplifiers 25 and 30, respectively. The outputs of amplifiers 25 and 30, hereinafter referred to as contacts a and b, respectively, are fed to amplifiers 35 and 40, respectively. The output of the amplifier 35 is supplied to a threshold device 45 having a predetermined threshold level V _T1 .

The output of the amplifier 40 is supplied to a threshold device 50 having a predetermined threshold level V _T2 . Threshold devices 45 and 50 convert the respective analog outputs of amplifiers 35 and 40 into logic control signals. If the output of the amplifier 35 is below the threshold level V _T1 , the threshold device 45 does not generate a control signal (its output is logic 0), but if the output of the amplifier 35 exceeds the threshold level V _T1 , The threshold device 45 generates a control signal (its output is logic 1). The threshold device 50 operates in a similar way. The outputs of the threshold devices 45 and 50, hereinafter referred to as contacts q and r, are supplied to the AND gate 55.

The outputs of amplifiers 25 and 30 are supplied to comparator-threshold circuit 60. This comparator-threshold circuit 60 generates a logic control signal only when the difference between the amplitudes of the two inputs of this circuit exceeds a predetermined level. In addition, the output of the amplifier 25 is supplied to the rise time sensing circuit 65, and the output of the amplifier 30 is supplied to the other rise time sensing circuit 70. Each rise time sensing circuit generates an analog output that is proportional to the rate of change of the input signal of the circuit.

The output of the rise time sensing circuit 65, hereinafter referred to as the contact d, the output of the rise time sensing circuit 70, hereinafter referred to as the contact e, and the output of the comparator-threshold circuit 60, referred to hereinafter as the contact c, are variable Three inputs to the delay circuit 75 are configured. This variable delay circuit 75 generates a logic control signal for a predetermined fixed period after receiving the control signal at all three input terminals.

The outputs of the amplifiers 25 and 30 are also supplied to the double time constant circuit 80 via a pair of single station switches 85 and 86. The state of the pair of switches 85 and 86 is controlled by the switch driver 90. The switch driver 90 is controlled by the output of the comparator-threshold circuit 60. If the comparator-critical circuit 60 generates a control signal, the switch driver 90 drives the pair of switches 85 and 86 in the closed state, and if the control signal is not generated, the switch driver Drives 85 and 86 in the open state. Therefore, the double time constant circuit 80 receives the outputs of the amplifiers 25 and 30 when the comparator-critical circuit 60 generates a logic control signal (ie, when the contact c is "high"). .

When the pair of switches 85 and 86 are closed, the double time constant circuit 80 is charged by the potential at the contacts a and b. The outputs of the double time constant circuit 80, hereinafter referred to as contacts g and h, are supplied to the double threshold circuit 95. The double threshold circuit 95 converts the analog signal at the contacts g and h into a logic signal called contacts k and m hereinafter. The two outputs of the double threshold circuit 95 are supplied to the input of the AND gate 98.

The output of AND gate 98, hereinafter referred to as contact n, the output of comparator-threshold circuit 60, and the output of variable delay circuit 75, hereinafter referred to as contact f, constitute the input to NOR gate 99. do. The output of NOR gate 99, hereinafter referred to as contact P, constitutes a third input to AND gate 55.

The output of AND gate 55, hereinafter referred to as contact s, is supplied to an electromechanical fire extinguishing device (not shown).

In most cases, large amplitude optical signals take longer to attenuate than small amplitude optical signals. Therefore, by charging the time constant circuit with the amplitude of the optical signal (long or short wavelength or both), the attenuation of the time constant circuit can be used to model or simulate the attenuation of the optical signal in the event of no fire. have.

Rise time variable delay operates in a similar manner. When an anti-aircraft projectile penetrates the surface of an airplane, it can be stimulated to generate a fast rising optical signal. This is especially true at long wavelengths. As a result, the time constant circuit, in which the delay is increased with the rise time of the optical signal, provides a short delay (i.e., in the range of 1 to 30 msec) for the fast rising signal, thereby releasing the extinguisher in almost accurate time. However, for very low rise times (a few tenths of a second), such as may occur when a mechanic moves around, a very long delay (several seconds) may occur.

Therefore, the advantage of delay over rise time is that it can increase immunity to ordinary false alarms that cause stimulation, and the delay over amplitude better simulates delay in projectile penetration and more effectively identifies between flash and fire. To do it.

The operation of the detector system of FIG. 1 is shown in the timing diagram of FIG. The scenario shown in FIG. 2 occurs when a projectile or anti-aircraft debris explodes through the walls of the area monitored by the detector system 10 to cause a fire. When projectile anti-aircraft debris penetrates through the wall, a flash of radiant energy emanates. This flash includes the relatively fast rising short wavelength component detected by the photon detector 15 to generate the waveform shown at contact point a in FIG. This flash also includes the relatively slow rising long wavelength component detected by the thermal detector 20 to generate the waveform shown at contact point b in FIG.

If the waveform at the contact a exceeds the threshold V _T1 at time t ₁ , the signal at the contact q rises to logic 1 and remains on while the waveform at the contact remains above the threshold V _T1 . If the short wavelength component of the flash continues to rise faster than the long wavelength component, the difference between these amplitudes causes the comparator-critical circuit 60 to generate a logic control signal at time t ₂ . The signal at contact c activates the switch driver 90 to drive a closed pair of switches 85 and 86 of the switch driver 90, thereby converting the signal at contacts a and b into a double time constant circuit ( 80), resulting in the waveforms shown at contacts g and h in FIG.

Once the double time constant circuit 80 is charged, the waveform at the contacts g and h triggers the dual threshold circuit 95 at time t ₂ , generating a logic control signal at the contacts k and m. Since the two input signals of the AND gate 98 are both logic ones, a logic control signal is generated at time t ₂ . NOR gate 99 generates a logic control signal when all inputs are logic zero. When the comparator-threshold circuit 60 generates a control signal at time t ₂ , the output of the NOR gate is suppressed, preventing the control signal from being generated at contact s.

As the relatively slow rising long wavelength component of the flash increases, the rise time sensing circuit 70 generates an output. At time t ₃ , the outputs of the two rise time sensing circuits are of sufficient magnitude to turn on the variable delay circuit 75 and the control signal for a predetermined period (here t ₃ to t ₇ ) by the variable delay circuit 75. Is generated. The rapid rise time generated by the penetration of the shell in the period in which the variable delay circuit generates the control signal should be set to achieve a shorter delay than the delay of the amplitude variable delay circuit. Therefore, the variable amplitude delay circuit controls the evolution of the extinguisher during current damage.

However, for slower rise time signals, the variable delay circuit 75 is experimentally set so that the delay can be combined to suppress a malfunction due to, for example, the mechanic's movement.

The slow rising long wavelength component of the flash increases above the threshold level V _T2 at time t ₅ , resulting in a logical one waveform at contact r. At time t ₆ , the short wavelength component of the attenuated flash falls when the long wavelength component continues to increase due to the fire ignited by the projectile or shell debris. The difference between these amplitudes falls below the threshold level, causing the comparator-threshold circuit to stop generating control signals as can be seen at contact c at time t ₆ . This causes the pair of switches 85 and 86 to open and the output of the double time constant circuit 80 begins to attenuate. When the waveform at contact g or h attenuates below the threshold of double threshold circuit 95, one of the inputs (contact k here) is removed from AND gate 98 at time t ₇ so that the output is logical. To return to zero.

At time t ₈ , the inputs of the NOR gate 99 all go to logic zero, and the waveform at the contact p rises to logic one. Therefore, all three inputs of the AND gate 55 become logic one and the AND gate 55 generates an output control signal at time t ₈ . This control signal can be used to release the extinguishing material to extinguish the building fire before it becomes uncontrollable.

If no fire occurs due to projectile or shell debris, the waveform at contacts a and / or b will be below the respective threshold level V _T1 or V _T2 . In this case, at the contacts q and / or r, the logic becomes 0, and the AND gate 55 does not generate an output control signal at time t ₈ .

The particular circuit, or circuit form, that suppresses the release of the extinguisher for a period sufficient to cause the flash to disappear is not limited to that shown in the embodiment of FIG. Another three channel detector system 100 is shown in FIG. This detector system 100 has a photon detector 105 and a heat detector 110, each capable of detecting radiant energy within a predetermined spectrum band and generating an output proportional to the amplitude of the detected radiation. Like the system of FIG. 1, the photon detector detects radiation within a 0.7 to 1.2 micron or 0.1 to 1.2 micron bandwidth, for example, and the thermal detector is within a 7 to 30 micron or 2.0 to 5.0 micron bandwidth, for example. It can work. The output of the photon detector is amplified by the amplifier 115 and the output of the thermal detector 110 is amplified by the amplifier 120.

The outputs of amplifiers 115 and 120, hereinafter referred to as contacts u and v, are fed to the input of comparator-threshold circuit 145. This comparator-threshold circuit generates a control signal at contact y whenever the difference between the amplitudes of its input signals exceeds a predetermined threshold. The outputs of amplifiers 115 and 120 are also fed to amplifiers 125 and 130, which are also fed to threshold circuits 135 and 140, respectively. Threshold circuit 135 generates a control signal at contact w when its input exceeds a predetermined threshold V _T3 , and threshold circuit 140 generates a contact signal when its input exceeds a predetermined threshold V _T4 . Generate a control signal at x. The outputs of the threshold circuits 135 and 140 constitute two inputs to the AND gate 155.

The delay function of the detector system 100 is performed by the fixed delay circuit 150. Fixed delay circuit 150 generates a logic control signal at contact z when there is no input signal from comparator-threshold circuit 145. When the comparator-threshold circuit 145 generates a logic control signal, the fixed delay circuit 150 stops generating the control signal during the input signal period and for a predetermined fixed predetermined period (delay period). Since the output of the fixed delay circuit 150 includes a third input to the AND gate 155, the output control signal at the contact zz is suppressed during the delay period.

The operation of the detector system 100 is shown in the timing diagram of FIG. 4 using the same scenario shown in FIG. When the short wavelength component of the flash rises above the threshold level V _T3 at time t ₁₁ , the output of the threshold circuit 135 is increased to logic 1 as shown at the contact w in FIG. If the difference between the amplitudes of the waveforms u and v exceeds the threshold of the comparator-threshold circuit 145 from time t ₁₂ to t ₁₃ , logic 1 is generated to the fixed delay circuit 150 (contact point y in FIG. 4). Supplied. The fixed delay circuit 150 stops generating a logic control signal at time t ₁₂ , as shown at contact z in FIG. 4, and the output of this fixed delay circuit is determined by the comparator-threshold circuit 145 at time t _13. The logic remains zero until the control signal generation is stopped for a later fixed predetermined period t ₁₃ to t ₁₅ .

At time t ₁₄ , the long wavelength component that causes the fire causes the waveform at contact V to exceed threshold V _T4 , and threshold circuit 140 generates logic one. When the fixed predetermined period of the fixed delay circuit 150 has elapsed time t ₁₅ , the fixed delay circuit 150 generates logic 1 again. Since all inputs of AND gate 155 are logic one, AND gate 155 generates an output control signal that can be used to release the extinguishing material to extinguish the generated fire.

The above described embodiments merely illustrate a number of possible special embodiments that may represent the principle application of the present invention. Many other devices may be devised in accordance with the principles of the invention by those skilled in the art without departing from the principles and scope of the invention.

Claims (4)

A detector system responsive to a fire or explosion, comprising: a first radiant energy detector for generating a first control signal when the first detector detects electromagnetic energy in a first spectrum band having an amplitude greater than a first predetermined threshold level; A first control signal device 45 responsive to 15), a second radiation to generate a second control signal when the second detector detects electromagnetic energy in a second spectrum band having an amplitude greater than a second predetermined threshold level; The second control signal device 50 responsive to the energy detector 20, the third time each time the ratio of the amplitude of the energy detected by the first detector and the energy detected by the second detector exceeds the third predetermined threshold level. The third control signal device 60 responsive to the first and second radiant energy detectors to generate a control signal, and generates a fourth control signal when the third control signal is not generated, but when the third signal is generated. Of course, the fourth control signal device 99 responsive to the third control signal so as not to generate the fourth control signal for a predetermined threshold time after the third control signal is stopped, and the first, second, and first A dual spectrum fire detector with an identification function, comprising an output gate device 55 responsive to first, second and fourth control signals to generate an output signal only when all four control signals are generated simultaneously. The dual spectrum fire detector of claim 1, wherein a third control signal is generated when the amplitude of the first detector output exceeds the amplitude of the second detector output. 10. The dual layer of claim 1, wherein the first spectrum band is a broad spectrum band in the 0.1 to 2.0 micron wavelength region and the second spectrum band is a broad spectrum band in the 5 to 30 micron wavelength region. Spectrum fire detector. The dual spectrum fire detector of claim 1, wherein the first spectral band is an optical spectral band in the 0.1 to 1.2 micron wavelength region and the second spectral band is an optical spectral band in the 2.0 to 5.0 micron wavelength region. .

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