RU64409U1 - COMBINED FIRE DETECTOR FOR ROOM WITH AN AGGRESSIVE AND (OR) EXPLOSIVE ENVIRONMENT - Google Patents

Abstract

The invention relates to a fire alarm technique, namely, to combined fire detectors and can be used to detect a fire when the ambient temperature and / or smoke appear at the detector installation site. The objective of the utility model is to expand the scope by increasing the reliability of fire detection, the life of the detector, the safety of the detector when operating in an aggressive and (or) explosive atmosphere. The technical result is achieved by the fact that in the known combined fire detector containing a measuring chamber including a temperature sensor and a smoke sensor, including a radiator and a receiver, a signal processing unit, the first output of which is connected to a smoke sensor, and the second output of the signal processing unit is connected to the sensor input temperature, and the alarm driver, the reference voltage generation unit and the comparator unit, the smoke detector output is connected to the first input of the formator unit of the reference voltage and the first input of the comparator unit, the output of the temperature sensor is connected to the second input of the reference voltage generation unit and the second input of the comparator unit, the output of which is connected to the input of the signal processing unit, the third output of which is connected to the input of the alarm notification generator, the output of which is a signal output detector, and the third and fourth inputs of the comparator unit are connected respectively to the first and second outputs of the unit for forming the reference voltage, according to useful models, the measuring chamber is hermetically sealed, while the smoke detector further comprises a chimney with a transparent wall mounted between the emitter and the receiver, reflectors mounted outside the chimney with the possibility of multiple passage of the probe laser beam through the chimney from the emitter to the receiver, a red filter installed in front of the photodetector and the temperature sensor contains a violet LED connected to a power amplifier and irradiating the surface of the “sheet” created and h thermosensitive luminescent optical fibers placed on a transparent wall of the chimney, when

This output ends of the optical fibers are assembled into a bundle and output to a photoresistor connected to an amplifier, the output of which is the output of the temperature sensor. The inventive utility model can be widely used in fire alarm systems in rooms, in vehicles, warehouses and other objects, because the inventive detector maintains high reliability of fire detection, both in normal conditions and in aggressive (chemical production) or explosive (special production) environments.

Description

The invention relates to a fire alarm technique, namely, to combined fire detectors and can be used to detect a fire when the ambient temperature and / or smoke appear at the detector installation site.

Known thermal fire detector for a closed explosive room (patent RU No. 2031446, IPC G08B 17/06. Publ. 03/20/1995) designed to signal the occurrence of a fire in an indoor environment with an explosive atmosphere, which responds to an increase in ambient temperature.

This detector contains a heat-sensitive thread located in the room and protected by a perforated casing, enveloping the rotary unit of the thread tensioner and connected at one end to a sealing spring-loaded valve, and the other through a rod with a spring-loaded contact interacting with the signaling contact.

The device for tensioning the thread includes a spring-loaded fork, a rotary unit, a protective casing, a direction indicator.

The detector operates as follows. In the event of an increase in temperature during ignition or decomposition of an explosive product in the room, the heat-sensitive thread breaks, and the contact of the signaling device closes, which turns on the alarm system and the gas fire extinguishing system. At the same time

with this, the second end of the heat-sensitive thread releases a spring-loaded valve, when opened, the closed room is connected to the atmosphere, thereby creating a condition for the air contained in the room to exit and be replaced by a fire-extinguishing gas composition.

The economic effect is to prevent possible emergency situations during transportation, storage or production of explosive materials.

The disadvantage of the detector is the lack of possible consideration of the variety of conditions under which a fire occurs, for example, the presence of smoke, which leads to an increase in the probability of false alarms.

Among the combined fire detectors, a device is known that responds to the appearance of two factors, for example, smoke, as well as increased temperature at the facility (US patent No. 6195011, IPC, 2001).

The device contains a first smoke detector and a second temperature sensor, the outputs of which are connected to the inputs of the signal processing unit through the corresponding first and second analog-to-digital converters, the first output of which is connected to the input of the first analog-to-digital converter and the first smoke sensor, the second output of the signal processing unit is connected to the input of the second analog-to-digital converter and the second temperature sensor, and the third output of the signal processing unit is the signal output of the detector.

The fire notification in the device is generated according to the OR logic when one of the controlled factors reaches the threshold level, as well as when both factors grow together if the calculated coefficient of their mutual correlation reaches the set threshold value.

However, it is known that an unsteady, rapidly changing value of factors (fluctuations in smoke and temperature) is characteristic of the initial stage of a fire. Therefore, during this period, the value of the cross-correlation coefficient may be small, which does not cause the device to trip, as a result of which the reliability of the device is reduced.

In addition, since a non-hermetic measuring chamber is used, the reliability of fire detection and the life of the detector is reduced due to contamination or degradation of the optoelectronic elements passing through the aerosol stream, in addition, due to safety conditions, the presence of open electrical contacts inside the measuring chamber precludes the use of a detector in explosive rooms.

Partially indicated disadvantages are eliminated in the fire detection device, which is closest to the inventive combined fire detector (patent RU No. 2275688, IPC G08B 17/06, G08B 17/10, publ. 04/27/2006).

The circuit of the prototype device is more perfect from the point of view of deciding on the formation of an alarm message.

The detector contains a first smoke sensor, a second temperature sensor, a reference voltage generating unit, a comparator unit, a signal processing unit, and an alarm notification generator.

The output of the first smoke detector is connected to the first input of the reference voltage generating unit and the first input of the comparator unit, the output of the second temperature sensor is connected to the second input of the reference voltage generating unit and the second input of the comparator unit, the output of which is connected to the input of the signal processing unit, the first output of which is connected to the input of the first sensor, the second output of the signal processing unit is connected to the input of the second sensor, the third output of the signal processing unit is connected to the input of the alarm driver alarm, the output of which is the signal output of the device.

The first smoke detector contains a power amplifier, the outputs of which are connected to a radiating LED, and a light energy receiver in the form of a photodiode, outputs connected to a signal amplifier. The input of the power amplifier is the input of the first smoke sensor, the output of the signal amplifier is the output of the smoke sensor.

The second temperature sensor contains a thermistor connected to the amplifier, the output of which is the output of the temperature sensor, and the input is the control input of the amplifier.

The reference voltage generating unit contains the first and second reference voltage drivers, the first input of the reference voltage generating unit is the input of the second reference voltage driver, the output of which is the second output of the reference voltage generating unit, the second input of the reference voltage generating unit is the input of the first reference voltage generating device, the output of which is the first output of the block forming the reference voltage.

The comparator block contains the first comparator, the second comparator and the logical element "OR". the comparator outputs are connected to the inputs of the OR gate, the output of which is the output of the comparator unit, the first and second inputs of the comparator unit are respectively the output of the first smoke sensor and the output of the second temperature sensor. Third and fourth block inputs

the comparators are respectively the first and second outputs of the block forming the reference voltage.

The signal processing unit comprises a setting pulse generator, a counter and a pulse generator. The first input of the counter is the input of the signal processing unit, and its output is the third output of the signal processing unit. The output of the installation pulse generator is connected to the second input of the counter, the first output of the pulse generator is connected to the third input of the counter, and the other two outputs of the pulse generator are the first and second output of the signal processing unit, respectively.

Voltage diagrams characterizing the operation of the detector are shown in Fig.5, Fig.6.

Combined fire detector operates as follows.

Under normal environmental conditions, after turning on the power, the generator of the setting pulse returns the counter to its initial state, at which a logical zero signal is generated at its output, indicating the absence of a fire. The generator generates voltage pulses at its outputs that enter the first and second sensors. In the first sensor, the pulse is amplified in the amplifier and leads to the emission of the light pulse by the converter into the optical camera in the infrared frequency range. If there are no particles of smoke in the chamber, reflected light does not reach the photodetector, and the amplitude of the signal U _C2 (Figure 5) at the amplifier output is small. In this case, the second driver of the reference voltage generates a set maximum threshold voltage U _P3 (Fig.6), supplied to the input of the comparator.

The voltage pulse from the generator opens the amplifier, from the output of which a normalized signal corresponding to the normal ambient temperature is supplied to the input of the comparator U _C4 (Fig.6) and the input of the second driver of the reference voltage. At normal ambient temperature, the driver generates a set maximum threshold voltage U _P1 (Figure 5), which is input to the comparator.

In the absence of a fire, the signals coming from the outputs of the first and second sensors to the corresponding inputs of the comparators have an amplitude much lower than the threshold voltages supplied from the outputs of the reference voltage conditioners. Therefore, the outputs of the comparators are constantly present logic zero signals received at the corresponding inputs of the logical element "OR". As a result, at the output of the OR gate, a logic zero signal is generated, which, entering the first input

counter, blocks it for counting pulses from the generator. The logical zero signal generated at the output of the counter leads to the formation of a “Norm” notification unit, in which the indicator light does not light, and the electronic key included in the fire alarm loop is closed.

In a fire with only one factor, for example smoke during smoldering cotton, the appearance of smoke particles in the optical chamber of the first sensor will cause an increase in the signal at the amplifier output (curve U _C1 in FIG. 5). Since the temperature of the medium at the detector installation site does not practically change, the comparator threshold voltage supplied from the former remains at its maximum (curve U _P1 in FIG. 5). After reaching the threshold value at the time t _{2 by the} voltage U _C1 , the pulses of the logical unit appear at the output of the comparator, which are fed to the input of the logical element "OR" and cause the appearance of pulses of the logical unit at its output. After the accumulation of a certain number of these pulses by the counter for a certain time, which constitutes a delay in operation, a logical unit signal appears at the output of the counter, which is fed to the input of the unit and causes the formation of a "Fire" notification. In this case, the light indicator turns on in the continuous glow mode, the electronic key opens and closes the line of the fire alarm loop. After decreasing the smoke concentration, the pulses of the logical unit from the output of the "OR" element cease, and after a certain time the detector switches back to standby mode.

In a fire with only heat, for example, during the burning of alcohol, an increase in temperature will cause an increase in the signal at the output of the amplifier (curve U _C3 in FIG. 6). Since there is practically no smoke in this case, the voltage of the threshold of the comparator supplied from the former remains maximum (curve U _P3 in Fig.6). After reaching the threshold value at the time t _{4 by the} voltage U _C3 , pulses of a logical unit appear at the output of the comparator, which pass through the OR logic element and are accumulated by the counter, which causes the detector to operate as described above.

The real, almost most common fire associated with the burning of various materials, for example cellulose-containing, is accompanied by both the formation of smoke and an increase in temperature. In this case, the voltages at the inputs of the comparator will correspond to the curve U _П2 and U _C1 in Fig. 5, and the voltages at the inputs of the comparator will correspond to the curve U _П4 and U _C3 in Fig. 6. Depending on the nature of the combustible load and the characteristics of the fire, the control signal can reach a threshold value at either the first or second

comparator. However, in any case, since t ₁ <t ₂ and t ₃ <t ₄ in the known detector, a significant reduction in the time of detection of a real fire is achieved.

However, the disadvantage of the combined detector (patent RU No. 2275688, MPK G08B 17/06, G08B 17/10, publ. 04/27/2006), is the limited scope - due to reduced reliability of fire detection and the life of the detector due to contamination and ( or) degradation of optoelectronic elements by an aerosol stream. In addition, according to safety conditions, the presence of open electronic contacts inside an impermeable measuring chamber precludes the use of the detector in hazardous areas.

The objective of the utility model is to expand the scope by increasing the reliability of fire detection, the life of the detector, the safety of the detector when operating in an aggressive and (or) explosive atmosphere.

The technical result is achieved by the fact that in the known combined fire detector containing a measuring chamber including a temperature sensor and a smoke sensor, including a radiator and a receiver, a signal processing unit, the first output of which is connected to a smoke sensor, and the second output of the signal processing unit is connected to the sensor input temperature, and the alarm driver, the reference voltage generation unit and the comparator unit, the smoke detector output is connected to the first input of the formator unit of the reference voltage and the first input of the comparator unit, the output of the temperature sensor is connected to the second input of the reference voltage generation unit and the second input of the comparator unit, the output of which is connected to the input of the signal processing unit, the third output of which is connected to the input of the alarm notification generator, the output of which is a signal output detector, and the third and fourth inputs of the comparator unit are connected respectively to the first and second outputs of the unit for forming the reference voltage, according to useful models, the measuring chamber is hermetically sealed, while the smoke detector further comprises a chimney with a transparent wall mounted between the emitter and the receiver, reflectors mounted outside the chimney with the possibility of multiple passage of the probe laser beam through the chimney from the emitter to the receiver, a red filter installed in front of the photodetector and the temperature sensor contains a violet LED connected to a power amplifier and irradiating the surface of the “sheet” created and h thermosensitive luminescent optical fibers located on the transparent wall of the chimney, when

This output ends of the optical fibers are assembled into a bundle and output to a photoresistor connected to an amplifier, the output of which is the output of the temperature sensor.

In the inventive device, the known units, as well as the comparators in the unit of comparators can be performed identically to fire detectors.

The inventive design of a combined fire detector for rooms with an aggressive and (or) explosive atmosphere, thanks to the sealing of the measuring chamber, provides reliable protection of the optoelectronic elements from pollution, erosion and chemical exposure to the environment, which significantly increases the reliability of fire registration and the life of the detector, at the same time eliminates the possibility of an emergency when a spark occurs on the contacts of optoelectronic elements in rooms with explosive oh environment.

Thanks to the proposed design of the smoke sensor, the laser beam, reflected from two mirrors, crosses the transparent walls of the chimney three times and then gets on the red filter, which protects the phototransistor from the emission of the violet LED.

Since the absorption capacity of smoke:

ζ = 1-exp (-α _l · X), where:

α _l - spectral absorption coefficient

X is the optical density of the smoke,

increasing the length of the laser beam leads to an exponential increase in the absorption capacity of the cross section of the chimney, i.e. to increase the sensitivity of the sensor to the presence of smoke compared to the prototype. Due to the fact that the proposed detector uses a red rather than an infrared beam, there is an additional increase in the sensitivity of the smoke sensor, since the light scattering coefficient:

β ~ λ ^-4 ,

Where:

λ is the radiation wavelength, i.e. with decreasing wavelength, the intensity of light scattering by smoke increases sharply.

The invention is illustrated by drawings, where:

figure 1 presents the design of the inventive combined fire detector:

figure 2 presents a schematic diagram of the inventive combined fire detector;

figure 3 presents a diagram of the change in time (t) of the output voltage (U _B1 ) of the smoke detector;

figure 4 presents a diagram of the change in time (t) of the output voltage (U _B2 ) of the temperature sensor;

figure 5, figure 6 presents voltage diagrams characterizing the operation of the detector (prototype);

Figure 1 shows such designations: a protective grid 1, a chimney 2, laser beams 3, 4, 5, a transparent wall 6 of the measuring chamber 7 emitting a laser diode 8, a phototransistor 9 with a red filter, reflectors 10, 11, a pressure ring 12, upper and lower sealed covers 13, 14, sealed connector 15, “sheet” of luminescent optical fibers 16, purple LED 17, fiber optic bundle 18, photoresistor 19.

Figure 2 shows the following notation:

2 - chimney;

6 - transparent wall of the measuring chamber;

8 - emitting laser diode;

9 - phototransistor;

10, 11 - reflectors;

16 - “sheet” of luminescent optical fibers;

17 - purple LED;

18 - fiber optic bundle;

19 - photoresistor;

20 - smoke sensor;

21 - temperature sensor;

22 - block forming the reference voltage;

23 - block comparators;

24 - signal processing unit;

25 - shaper alarm notification;

26 - power amplifier;

27 - signal amplifier;

28 - amplifier;

29 - amplifier;

30 - the first driver of the reference voltage;

31 - the second driver of the reference voltage;

32 - the first comparator of the reference voltage;

33 is a second comparator of the reference voltage;

34 - logical element "OR";

35 - generator installation pulse;

36 - pulse counter;

37 - pulse generator;

38 - electronic key;

39 - indicator light.

The detector measurement circuit contains (FIG. 2) a first smoke sensor 20, a temperature sensor 21, a reference voltage generation unit 22. a comparator unit 23, a signal processing unit 24, an alarm notification generator 25

The output of the smoke detector 20 is connected to the first input of the reference voltage generating unit 22 and the first input of the comparator unit 23, the output of the second temperature sensor 21 is connected to the second input of the reference voltage generating unit 22 and the second input of the comparators 23, the output of which is connected to the input of the signal processing unit 24 the first output of which is connected to the input of the sensor 20, the second, third outputs of the signal processing unit 24 are connected to the input of the sensor 21, the fourth output of the signal processing unit 24 is connected to the input of the driver alarm notification 25, the output of which is the signal output of the device.

The smoke sensor 20 contains a power amplifier 26, the outputs of which are connected to a laser emitting LED 8. a transparent wall 6 of the measuring chamber, a chimney 2, reflectors 10, 11, a light energy receiver in the form of a phototransistor 9 with a red filter, the outputs connected to a signal amplifier 27. Input the power amplifier 26 is the input of the smoke sensor 20, the output of the signal amplifier 27 is the output of the smoke sensor 20.

The temperature sensor 21 contains a violet LED 17, the input of which is connected to a power amplifier 28, connected to the other output of block 24, a “sheet” (layer) 16 made of luminescent optical fibers, placed on the side surface of the transparent wall 6 of the chimney 2 (using a pressure ring ), or from the inside or outside of the transparent wall. The most effective from the point of view of ensuring the highest heating rate of the LEDs is to install in the middle of the chimney 2 between the transparent wall 6 of the chimney 2 and the surface of the clamping metal ring located in the middle of the chimney. The output ends of the luminescent optical fibers are assembled in a fiber optic bundle 18, the radiation receiver in the form of a photoresistor 19 connected to

the amplifier 29, the output of which is the output of the temperature sensor 21, and the input is the control input of the amplifier 29 connected to the third output of the block 24.

The reference voltage generating unit 22 contains the first 30 and second 31 reference voltage drivers, the first input of the reference voltage generating unit 22 is the input of the second reference voltage driver 31, the output of which is the second output of the reference voltage generating unit 22, the second input of the reference voltage generating unit 22 is an input the first voltage reference driver 30, the output of which is the first output of the voltage reference forming unit 22.

The comparator unit 23 contains a first comparator 32, a second comparator 33 and an OR gate 34, the outputs of the comparators 32, 33 are connected to the inputs of an OR gate 34, the output of which is the output of the comparators 23, the first and second inputs of the comparators 23 respectively, the output of the smoke detector 20 and the output of the temperature sensor 21. The third and fourth inputs of the comparator unit are respectively the first and second outputs of the unit for generating the reference voltage 22.

Signal processing unit 24 comprises a setting pulse generator 35, a counter 36 and a pulse generator 37, the first input of counter 36 is the input of signal processing unit 24, and its output is the fourth output of signal processing unit 24. The output of the setting pulse generator 35 is connected to the second input of counter 36 , the first output of the pulse generator 37 is connected to the third input of the counter 36, and the remaining three outputs of the pulse generator 37 are respectively the first, second and third outputs of the signal processing unit 24. The electronic key 38 includes Indicator 39.

Below are descriptions of the detector design shown in FIG. 1 and the measurement circuit shown in FIG. 2.

The design of the proposed combined detector (Figure 1) works as follows.

Smoke D passes through a protective grid 1 installed on the inlet end of the chimney 2 and intersects the laser beams 3, 4, 5 and moves along the chimney 2 formed by the transparent wall 6 of the measuring chamber 7. The emitting laser diode 8, a phototransistor 9 with a red filter and two reflectors 10 , 11 form a closed optical circuit, which provides three-fold passage of laser beams 3, 4, 5 through the chimney 2.

The optical axes of the beams 3, 4, 5 are located above the metal clamping ring 12, by means of which a “sheet” of luminescent optical fibers is fixed on the transparent wall 6 of the measuring chamber 7. Upper 13 and lower 14

sealed covers protect all elements of the measuring chamber 7 from aggressive and (or) explosive atmospheres. Communication elements of the measuring chamber 7 is carried out through a sealed connector 15.

Figure 3 shows a diagram of the change in time t of the output voltage U _{B1 of the} prototype smoke detector. in which the phototransistor 9 is included in the Darlington analog circuit.

At an early stage of combustion, i.e. at a low smoke density, the analog signal at the output of the Darlington circuit initially increases due to the appearance of an additional light flux formed as a result of scattering by smoke particles not only of rays 3, 4, 5, but also as a result of scattering of part of the rays 3, 4, 5, which is reflected from the surface of the transparent wall 6 inside the chimney 2 (section 1-2 in figure 3).

With increasing smoke density, the output signal of the phototransistor decreases (section 2-3 in Figure 3) since the effect of light absorption begins to prevail: not only rays 3, 4, 5, but also scattered rays are absorbed. After the cessation of combustion, the output signal of the phototransistor returns to its initial level (section 3-4 in Figure 3), after aeration of the room.

This nature of the dependence U _B1 (t) allows you to reliably distinguish the initial stage of the fire by increasing the output of the smoke detector.

Figure 4 shows a diagram of the change in time t of the output voltage U _{B2 of the} prototype temperature sensor shown in Figure 1 with an analog output (without amplifiers and generators).

A “sheet” 16 of luminescent optical fibers is illuminated by the pump radiation of a violet LED 17, and visible luminescence radiation, the intensity of which depends on the temperature of the “sheet”, is fed through a fiber optic bundle 18 to a photoresistor 19, the resistance of which changes and is recorded. The sensitivity range of the temperature sensor can be adjusted by changing the current of the violet LED 17. Section 1-2 (in Figure 4) corresponds to turning on the purple LED 17, section 2-3 corresponds to the standby mode, section 3-4 to the heating process of the “sheet” 16 of the luminescent optical fibers.

The temperature sensor works most efficiently at an ambient temperature of ≥50 ° C. The operation of the measuring circuit of the inventive utility model is similar to the operation of the device circuit (Figure 5, Figure 6) and is carried out as follows.

Under normal environmental conditions, after turning on the power, the generator of pulse 35 leads the counter 36 to its initial state, in which a logical zero signal is generated at its output, indicating the absence of a fire. The generator 37 generates voltage pulses at its outputs, which enter the smoke sensor 20 and the temperature sensor 21. In the sensor 20, the pulse is amplified in the amplifier 26, which causes the laser diode 8 to emit red light probing through the transparent wall 6 of the chimney 2, due to the presence of reflectors 10, 11.

The voltage pulse from the generator 37 in the sensor 21 is amplified in the amplifier 28, which leads to the emission of a violet LED on the “sheet” of luminescent optical fibers 16. The visible luminescent radiation of the fibers to the sheets assembled in the bundle 18 is supplied to the photoresistor 19. The voltage pulse from the generator 37 opens the amplifier 29, the output of which a normalized signal corresponding to a normal ambient temperature, is input to the comparator 33 U _C4 (6) and the input of the second reference voltage generator 30. During normal evap e environment generator 30 generates a prescribed maximum threshold voltage U _P1 (5), supplied to the comparator 32.

In the absence of a fire, the signals coming from the outputs of the sensor 20 and the sensor 21 to the corresponding inputs of the comparators 32, 33 have an amplitude much lower than the threshold voltages supplied from the outputs of the reference voltage formers 30, 31. Therefore, signals are constantly present at the outputs of the comparators 32, 33 logic zero, received at the corresponding inputs of the logical element "OR" 34. As a result, the output of the logical element "OR" 34 generates a logic zero signal, which, arriving at the first input of the counter 36, blocks it for counting that the pulses from the generator 37. The generated while the output signal of the counter 36, a logic zero results in the formation of an alarm signal generator 25, a notice "Norm" in which the LED 39 is not lit, and the electronic key 38 that is included in the fire alarm loop is closed.

In case of fire in the presence of only one factor, for example, smoke during smoldering of cotton, the appearance of smoke particles in the optical chamber of the sensor 20 will first cause an increase in the signal at the output of amplifier 27 (curve U _C1 in FIG. 5). Since the temperature of the medium at the installation site of the detector does not practically change, the threshold voltage of the comparator 32 supplied from the former 30 remains at its maximum (curve U _P1 in FIG. 5). After reaching at time t ₂

voltage U _{C1 of the} threshold value at the output of the comparator 32 there are pulses of a logical unit, which are fed to the input of the logical element "OR" 34 and cause the appearance of pulses of a logical unit at its output. After the accumulation of a certain number of these pulses by the counter 36 for a certain time, which constitutes a delay in operation, a logic unit signal appears at the output of the counter 36, which is fed to the input of the shaper 25 and causes the formation of a "Fire" notification. In this case, the light indicator turns on in the continuous glow mode, the electronic key opens and closes the line of the fire alarm loop.

In a fire with heat only, for example, during alcohol burning, an increase in temperature will cause an increase in the luminescence intensity of the “sheet” 16, and as a result, an increase in the signal at the output of the amplifier 29 (curve U _C3 in FIG. 6). Since virtually no smoke is generated, the threshold voltage of the comparator 33 supplied from the former 31 remains at its maximum (curve U _P3 in FIG. 6). After reaching the threshold value at the time t _{4 by the} voltage U _C3 , pulses of a logical unit appear at the output of the comparator 33, which pass through the OR gate 34 and are accumulated by the counter 36, which causes the detector to operate similarly to the one described above.

The real, almost most common fire associated with the burning of various materials, for example cellulose-containing, is accompanied by both the formation of smoke and an increase in temperature. In this case, the voltages at the inputs of the comparator 32 will correspond to the curves U _П2 and U _C1 in Fig. 5, and the voltages at the inputs of the comparator 33 will correspond to the curves U _П4 and U _C3 in Fig. 6. Depending on the nature of the combustible load and the fire characteristics, the control signal can reach a threshold value either at the first 32 or at the second 33 comparators.

Thus, the presence of a sealed measuring chamber provides the possibility of using the inventive combined detector in those difficult conditions - aggressive and (or) explosive atmospheres where known fire detectors cannot be used, which expands the scope of the claimed utility model.

In addition, the use of a thermo-maximum low-temperature temperature sensor (luminescent fiber has a diameter of 0.2 mm, which is much smaller than the diameter of a standard thermistor, equal to 3-4 mm.) Helps to reduce the thermal inertia of the temperature sensor used in the inventive detector.

The inventive utility model can be widely used in fire alarm systems in rooms, in vehicles, warehouses and other objects, because the inventive detector maintains high reliability of fire detection, both in normal conditions and in aggressive (chemical production) or explosive (special production) environments.

Claims (1)

A combined fire detector comprising a measuring chamber, including a temperature sensor and a smoke sensor, including an emitter and a receiver, a signal processing unit, the first output of which is connected to a smoke sensor, and the second output of the signal processing unit is connected to the input of the temperature sensor, and an alarm driver, block the reference voltage generation unit and the comparator unit, the smoke detector output is connected to the first input of the reference voltage generating unit and the first input of the compar unit sensors, the output of the temperature sensor is connected to the second input of the reference voltage generation unit and the second input of the comparator unit, the output of which is connected to the input of the signal processing unit, the third output of which is connected to the input of the alarm notification generator, the output of which is the signal output of the detector, and the third and fourth inputs block comparators are connected respectively with the first and second outputs of the block forming the reference voltage, characterized in that the measuring chamber is hermetically sealed, while The smoke detector additionally contains a chimney with a transparent wall mounted between the emitter and the receiver, reflectors installed outside the chimney with the possibility of multiple passage of the probe laser beam through the chimney from the emitter to the receiver, a red filter installed in front of the photodetector, and the temperature sensor contains a purple LED, connected to a power amplifier and irradiating the surface of the “sheet”, created from heat-sensitive luminescent optical fibers, p located on the transparent wall of the chimney, while the output ends of the optical fibers are assembled into a bundle and output to a photoresistor connected to an amplifier, the output of which is the output of the temperature sensor.