CN104459817B - Fire sign detection device and method - Google Patents

Abstract

The invention provides a fire sign detection device and method. The device comprises a shell, a shading hood, a suction fan, a master control unit and a detection assembly. The suction fan, the master control unit and the detection assembly are arranged in the shell, the suction fan is located at a suction inlet of an upper cover, the input end of the suction fan is connected with a fan control output end of the master control unit, a detection chamber of a maze structure is disposed in the inner space of the shell, the detection assembly arranged in the detection chamber comprises a light source module and a scatter receiving detection amplifier circuit module, the light source module comprises two emitting tubes and two collimating lenses, and the input ends of the two emitting tubes are connected with the light source control output end of the master control unit. Multi-information synthesis detection is combined with a sunk detection light path structure of special design so that sensitive detection of micro sign information in the pyrolysis process in a fire breeding stage can be achieved, meanwhile, categories of pyrolysis particles with different attributes are judged, early sign detection is achieved, and meanwhile reliability of a detector is greatly improved.

Description

Device and method for detecting fire symptoms

technical field

The invention belongs to the technical field of fire sign detection, and in particular relates to a fire sign detection device and method.

Background technique

Fires caused by electrical reasons account for a quarter of the fire accidents over the years. Therefore, electrical fire prevention is the top priority in fire safety, especially all kinds of power distribution cabinets, switch cabinets, control cabinets, etc., which carry electrical energy. For important functions such as transmission and distribution or signal decision-making, early detection of fires for such cabinet-type electronic control equipment has always been a practical need in safety production, and it is of great significance to prevent fires, protect people's lives and property, and avoid huge economic losses.

In all kinds of cabinet-type electronic control equipment, although there are overcurrent or residual current monitoring and protection devices to prevent failures, the hidden danger of heating is not only caused by overcurrent or residual current, but also due to poor contact, wrong matching of wire diameters and in-equipment Many factors such as the short circuit of the DC weak current part of the instrument can lead to abnormal heating of the conductor. The variety of fault types makes the existing electrical fire monitoring system highlight the lack of protection capabilities. Therefore, it is very necessary to carry out cabinet-type electrical control equipment from the perspective of fire detection and alarm Early warning and prevention of fire signs, research and development to provide targeted protection during the pyrolysis stage of fire incubation for such places.

The possible products and phenomena of the pyrolysis process in the fire breeding stage include three types of symptoms: smoke, temperature, and gas. According to the different pyrolysis combustibles, the above three types of products and phenomena may or may not occur, so relevant tests need to be carried out Research, determine the effective fire signs in the target protection site, and establish the experimental simulation method for the effective fire signs, and finally evaluate the technical direction of the possible detection technology for detecting the signs, and provide directional suggestions and related information for the development of sign detectors. The support of symptom characteristic law data.

The purpose of developing fire sign detectors is to provide early warning and protection capabilities in the fire breeding stage. Therefore, a high-sensitivity detection method must be established first to achieve sensitive detection of tiny symptom information during the pyrolysis process in the fire breeding stage. However, due to the weak sign information, it is easy to be submerged with the disturbances in the environment. High-sensitivity detection may lead to an increase in the false alarm probability of the sign detector in some cases. The sign detector is a feature of high-sensitivity signs The specific implementation of attribute recognition and detection technology, the selection of key components, the design of recognition algorithms, the design and improvement of circuit systems, the optimization of optical paths and the cooperation of various structural components all require repeated testing, analysis and adjustment during the development process. .

Contents of the invention

The object of the present invention is to provide a fire sign detection device and method.

Technical scheme of the present invention is:

A fire sign detection device, comprising: a casing, a hood, a suction fan, a main control unit and a detection assembly;

The housing includes an upper cover and a base. The suction fan, the main control unit and the detection component are all arranged in the housing formed by the fastening of the upper cover and the base. There is an air suction inlet in the center of the upper cover, and a shading is installed at the suction inlet of the upper cover. cover;

The main control unit is fixed at the base; the suction fan is located at the suction inlet of the upper cover, and the input end of the suction fan is connected to the fan control output end of the main control unit;

A detection chamber with a labyrinth structure is arranged in the inner space of the housing, and a detection assembly is arranged in the detection chamber, including a light source module for emitting a detection beam and a scattering reception detection amplification circuit module for receiving a scattered signal generated by the irradiation of the detection beam;

The light source module includes two emission tubes and two collimating lenses, and the input ends of the two emission tubes are respectively connected to the light source control output ends of the main control unit.

The scattering receiving detection amplifier circuit module includes three photosensitive sensors and three detection amplifier circuits; the output terminals of each photosensitive sensor are respectively connected to the input terminals of each detection amplifier circuit, and the output terminals of each detection amplifier circuit are respectively connected to the signal input terminal of the main control unit.

The light source module and the scatter receiving detection amplifying circuit module are mounted on the base in a clamping and fixing manner.

The detection chamber is provided with multiple exit pupil diaphragms, photosensitive areas and extinction light traps for multiple reflections and absorption of incompletely collimated paraxial stray light;

The multiple exit pupil diaphragm is located behind the collimating lens; the exit pupil diaphragm is designed with a sharp angle of 30°;

The photosensitive area is the place where the smoke particles in the gas pass through the channel of the detection chamber and the light beam emitted by the light source module intersects. The photosensitive area is cylindrical; the light source module, the scattering receiving detection amplifier circuit module, and the extinction optical trap are distributed on a spherical surface around the photosensitive area. ;

The extinction light trap is an optical trap, which adopts the design method of optical dead space. After entering the extinction light trap, the light enters the dead space after multiple reflections;

The light source module and the extinction light trap are symmetrically distributed to form a light source plane, the forward photosensitive sensor is arranged on one side of the extinction light trap, and the backward photosensitive sensor is arranged on the light source module side.

The housing is made of ABS engineering plastics, and the inner surface of the housing is coated with a shielding metal foil film to isolate external electromagnetic interference.

The photosensitive sensor adopts a sunken design, and its installation angle forms a spatial angle with the emitted light beam, and the installation plane of the photosensitive sensor is lower than the plane of the light source.

A shading sheet is arranged between the photosensitive area and the suction fan.

The method for detecting fire signs by using the fire sign detection device includes the following steps:

Step 1: The main control unit controls the suction fan to inhale the gas in the detection environment, and the gas enters the detection chamber of the housing through the suction inlet;

Step 2: The main control unit controls the two emission tubes to emit light beams sequentially in different emission modes at fixed time intervals. The light beams enter the photosensitive area after passing through the collimating lens. multiple reflection absorption;

The three different launch modes are as follows:

Emission mode 1: One emission tube emits a 50 ms beam;

Emission mode 2: Another emission tube emits a 50 millisecond beam;

Emission mode 3: two emission tubes emit 50 millisecond beams at the same time;

Step 3: When the light beam passes through the photosensitive area, if the gas contains fire sign particles, it will scatter;

Step 4: Three photosensitive sensors receive the scattered beams, the extinction trap absorbs the parallel beams, and the parallel beams not absorbed by the extinction trap are emitted through the through hole of the extinction trap and then absorbed by the hood;

Step 5: Three photosensitive sensors receive the fire sign particles and the scattered light signal generated by the emitted light beam is amplified by the photoelectric detection amplifier circuit and then transmitted to the main control unit;

Step 6: The main control unit calculates the background increment of scattered light received by the three photosensitive sensors in different emission modes;

Step 7: Calculate the ratio Kij of the background increments of scattered light received by the three photosensitive sensors in each emission mode, obtain the interval of the Kij value, and compare the interval of the Kij value with the Kij corresponding to the different types of fire symptom particles obtained in advance sampling Comparison of the standard interval of the value: if the interval of the Kij value falls into a certain standard interval, the current gas contains fire sign particles corresponding to the standard interval, and the fire sign particles determine whether there is a fire sign in the current detection environment.

The launch modes include:

Emission mode 1: One emission tube emits a 50 ms beam;

Emission mode 2: Another emission tube emits a 50 millisecond beam;

Emission mode 3: Both emission tubes emit 50ms beam simultaneously.

The fire symptom particles are dust, water vapor particles, diesel particles, PVC pyrolysis particles or wood pyrolysis particles.

Beneficial effect:

By adopting multi-information compound detection combined with the uniquely designed sunken detection optical path structure, the sensitive detection of tiny sign information in the pyrolysis process of the fire breeding stage can be realized, and the classification of pyrolysis particles with different attributes can be judged at the same time, so as to realize the detection of early signs. While detecting, the reliability of the detector is greatly improved.

Description of drawings

Fig. 1 is a schematic diagram of the principle of fire sign detection according to a specific embodiment of the present invention;

Fig. 2 is a schematic diagram of the overall structure of a fire sign detection device according to a specific embodiment of the present invention, wherein, 1 - upper cover, 2 - detection assembly, 3 - base;

Fig. 3 is a simplified schematic diagram of the internal structure of the detection chamber according to a specific embodiment of the present invention;

Fig. 4 is a schematic diagram of the three-dimensional structure of the section of the exit pupil diaphragm according to the specific embodiment of the present invention;

Fig. 5 is a schematic diagram of a three-dimensional structure of a cross-section of an extinction optical trap according to a specific embodiment of the present invention;

6 is a cross-sectional view of a sunken design structure of a photosensitive sensor according to a specific embodiment of the present invention;

FIG. 7 is a schematic diagram of a detection amplifier circuit according to a specific embodiment of the present invention;

Fig. 8 is a flowchart of a method for detecting fire signs according to a specific embodiment of the present invention.

detailed description

The specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings.

According to the corresponding conclusions of the study on the determination of fire signs and the selection of detection technology, the early signs of fire of typical combustibles in the target protection site are pyrolysis particles, which are a kind of aerosol particles, so they can be detected by light scattering technology. The principle of symptom detection is shown in Figure 1. A light source is used to irradiate the area where pyrolysis particles are introduced. In the absence of pyrolysis particles, the light propagates in a straight line. When there are pyrolysis particles, due to the scattering effect of the particles on light, the There is also scattered light in directions other than the straight-line propagation direction, and the detection of symptoms can be completed by collecting and sensing the scattered light.

The fire sign is a kind of weak information, so a high-sensitivity detection technology is required. The key to realizing symptom detection based on the principle of light scattering is to improve the signal-to-noise ratio between the scattered light intensity when there are pyrolytic particles and the background light radiation intensity received by the photoelectric conversion device without pyrolytic particles, while maintaining the scattered light intensity of different types of particles. Distinguishability of features for attribute identification.

Point detectors can locate the location of the fire when they constitute an automatic fire alarm system. For the symptom detectors designed to issue early warning during the fire breeding stage, the positioning capability provided by the point structure helps to quickly deal with faulty equipment and avoid Untimely treatment caused by the hidden trouble spot investigation process leads to greater losses. The air-breathing structure can provide more stable smoke in and out performance, and can effectively reduce the signal instability caused by the natural diffusion of smoke caused by the point structure. To sum up, in order to meet the actual needs, the best design of the detector structure in this embodiment should be a point-shaped structure with air-breathing capability.

According to the scattering theory, different single particles produce different scattering fields when they scatter light. For particle swarms, if the distance between particles is much larger than the particle size, the scattering field of the particle swarm is approximately the same as that of each single particle. The superposition of the scattered field, so property identification can be achieved by measuring the scattered field of the particle population.

A fire sign detection device, as shown in Figure 2, comprising: a housing, a hood, a suction fan, a main control unit and a detection assembly 2;

The housing is made of ABS engineering plastics, and the inner surface of the housing is coated with shielding metal foil to isolate external electromagnetic interference.

The housing includes an upper cover 1 and a base 3. The suction fan, the main control unit and the detection component 2 are all arranged in the housing formed by fastening the upper cover and the base. There is an air suction inlet in the center of the upper cover. Install a sunshade at the entrance.

The main control unit adopts C8051F410 chip. C8051F410 is an analog-digital hybrid chip with C51 core, which is widely used. Based on this chip, functions such as analog quantity acquisition, alarm calculation, and communication can be easily completed, which is very beneficial to simplifying circuit design and improving the stability of the entire system. After the detector is powered on, all function registers are reset first, and interrupts are turned off. Utilize on-chip flash to store address coding, besides, some important data needed in the working process are also stored in flash. Different environments and different working conditions cause the detectors to work in different environments. Therefore, as time changes, the background incremental value of the scattered light of the photosensitive sensor may fluctuate. For this reason, the background needs to be updated periodically . Considering that the environmental conditions cannot be changed suddenly, the change period of the background value of the analog quantity of the photosensitive sensor is much longer than that caused by pyrolysis particles or other interfering particles, so the interruption period of the background follow-up floating timer is set to be far It is used to detect the interrupt period of the timer. A sequence of probing periods is included in a local follow-float period.

The main control unit is fixed at the base 3; the suction fan is located at the suction inlet of the upper cover 1, and the input end of the suction fan is connected to the fan control output end of the main control unit;

A detection room with a labyrinth structure is set in the inner space of the housing, and the detection component is set in the detection room, including a light source module for emitting a detection beam and a scattering reception detection amplification circuit module for receiving a scattered signal generated by the irradiation of the detection beam; the light source module and The scatter receiving detection amplifying circuit module is installed on the base 3 in a clamping and fixing manner.

The light source module includes two emission tubes and two collimating lenses, and the input ends of the two emission tubes are respectively connected to the light source control output ends of the main control unit.

The scattering receiving detection amplifier circuit module includes three photosensitive sensors and three detection amplifier circuits; the output terminals of each photosensitive sensor are respectively connected to the input terminals of each detection amplifier circuit, and the output terminals of each detection amplifier circuit are respectively connected to the signal input terminal of the main control unit.

Filtering or isolating the stray light scattered by non-pyrolytic particles from the photosensitive sensor as much as possible is a necessary and sufficient condition to achieve high signal-to-noise ratio detection, and it is also a technical difficulty to achieve high-sensitivity detection. For this reason, in this embodiment, an optimized design for the optical path is carried out, and finally a detection chamber with excellent performance is obtained. As shown in Figure 3, the detection room is equipped with multiple exit pupil diaphragms, photosensitive areas and extinction light traps for multiple reflections and absorption of incompletely collimated paraxial stray light; a shading sheet is set between the photosensitive area and the suction fan , A filter is fixed at the front end of the suction fan.

In view of the fact that the technology of semiconductor laser diodes is very mature, and the price is low, and the volume is small, so this implementation mode adopts laser diodes as the emission tubes. The laser emitted by the semiconductor laser diode is a Gaussian beam, which is different from the helium-neon laser. Its divergence angle is wider, and the typical divergence angle is about θ _⊥ = ±10°, θ _|| = ±20°. If it is directly used in the detector A large part of the optical path cannot enter the optical trap, but causes multiple reflections of stray light in the detector. For this reason, a collimator lens is designed in front of the semiconductor laser beam, and the laser excitation place of the semiconductor laser diode is set at the collimator. At the focus of a straight lens. Collimating lenses are divided into aspherical lenses and spherical lenses. Among them, aspheric lenses are more difficult to process and have a low degree of standardization, but they can strictly collimate the light passing through the self-focus. Spherical lenses are available in a large number of standard specifications, which are easy to process and low in price, but they cannot be completely collimated for light rays at a large angle to the optical axis, and they still diverge after exiting the lens. Considering the ease of engineering processing and manufacturing, the spherical lens collimation method is adopted, and part of the collimation performance sacrificed is compensated by designing multiple exit pupil diaphragms. The multiple exit pupil diaphragms are located behind the collimating lens; the exit pupil diaphragms are designed with a sharp angle of 30°, as shown in Figure 4, the paraxial stray light that is not completely collimated will be absorbed by the multiple reflections of the adjacent exit pupil diaphragms , The periphery of the aperture is designed with a sharp angle, which can avoid secondary light pollution caused by filtering stray light, and greatly improves the collimation characteristics of the exit pupil laser beam.

The photosensitive area is the place where the smoke particles in the gas pass through the channel of the detection chamber and the light beam emitted by the light source module intersects. The photosensitive area is cylindrical; the light source module, the scattering receiving detection amplifier circuit module, and the extinction optical trap are distributed on a spherical surface around the photosensitive area. .

In order to ensure that all the laser exit pupil beams are absorbed as much as possible in the state of no pyrolysis particles, so that the background light intensity of the detection chamber received by the photosensitive sensor is relatively low, the extinction light trap shown in Figure 5 is designed, and the extinction light trap is The optical trap adopts the design method of the optical dead cavity. After entering the extinction optical trap, the light enters the dead zone after multiple reflections; In the small-angle cone, it is absorbed after multiple reflections by the cone surface, and a small part of the unreflected light on the optical axis and the light that is not completely absorbed are emitted through the through hole, which avoids part of the light being reflected back to the photosensitive area due to the closed hole The problem.

Most of the detectors based on the principle of light scattering are trying to expand the light-receiving range of the photosensitive sensor as much as possible, so that all the scattered light is received by the photosensitive sensor. However, in doing so, the energy of the light scattering field of the particles is mixed and superimposed, and it is impossible to distinguish the properties of the particles. In addition, the reflector used for light collection also increases the contaminated area, and the response performance of the detector will drift due to the dust on the mirror under long-term operation. Therefore, under the premise of optimizing the structure of the detection chamber, light source, photosensitive sensor, and detection amplifier circuit to ensure the detection sensitivity, a small-angle light-receiving channel is designed for the photosensitive sensor. This makes it impossible for scattered light at other angles outside the range of light collection angle θ±10° to reach the photosensitive sensor, ensuring the accuracy of angle positioning of laser scattered light when identifying particle properties. In addition, although the small-angle multiple exit pupil diaphragm reduces the total amount of light reaching the photosensitive sensor, it also suppresses the reflected stray light from other side walls in the case of no smoke, so that the background output of the photosensitive sensor is correspondingly reduced To a certain extent, it makes up for the shortcoming of collecting a small amount of scattered light. In addition, the photosensitive sensors are all placed under the detection chamber, between the detection chamber and the base. This sunken design avoids the situation that multiple photosensitive devices are in the dark room to block the diffusion of smoke when receiving from multiple angles. Appear.

The light source module and the extinction light trap are symmetrically distributed to form a light source plane, the forward photosensitive sensor is arranged on one side of the extinction light trap, and the backward photosensitive sensor is arranged on the light source module side. As shown in Figure 6, the photosensitive sensor adopts a sunken design, and its installation angle forms a spatial angle with the emitted light beam, and the installation plane of the photosensitive sensor is lower than the plane of the light source.

The photosensitive sensors are all placed under the plane composed of two emission tubes in the detection room. This sunken design avoids the formation of smoke caused by the formation of multiple photosensitive devices in the dark room when multiple photosensitive tubes receive scattered light at the same time. The unfavorable detection angle, and the installation of the detection sensor obliquely downward ensures that when the detector is working normally, the dust particles in the air will not fall to the surface of the sensor due to the influence of gravity, which greatly improves the reliability of the detector.

The photosensitive sensor adopted in this embodiment is a photosensitive diode. When the photodiode has light, it will generate a weak current. If the photodiode is reverse-biased, the weak current will also be amplified, and the magnitude of the weak current is proportional to the received light power. Therefore, based on photodiode scattered light detection, a detection amplifier circuit is required. Through experiments, it is found that the scattered light energy produced by pyrolysis particles with a concentration below 0.8% obs/m is extremely small, and the received light power is only at the level of 10 ^-10 ~ 10 ^-9 W when the photosensitive sensor receives light at a solid angle of 0.01 sr , for the current photosensitive sensor whose photoelectric conversion efficiency is on the order of 10 ^-1 A/W, its output current is only 10 ^-11 ~ 10 ^-10 A. Generally, the current signal is converted into a voltage signal for amplification. For this reason, a pre-transimpedance amplifier is designed to realize I/V conversion amplification, as shown in Figure 7. However, for current AD converters, at least it needs to be amplified to the mV level before reliable measurement is possible. Therefore, if a first-stage preamplifier is used, the feedback resistor R _f needs to be at least 1GΩ. However, the time constant brought by the feedback resistance of 1GΩ is huge, and the step response time reaches the second level. Therefore, the amplification factor of the previous stage is reduced, and a two-stage amplification circuit is used. The final amplification factor is R ₁ R ₈ /R ₅ . For the amplifying circuit, the selection of the operational amplifier is very important. For the measurement of small current signals, the input bias current and offset voltage of the operational amplifier must be very small. The OPA2340 is a precision operational amplifier, and its input bias current is typically 0.2 pA, which is lower than the photocurrent output of the photosensitive sensor, and the offset voltage is less than 2.5μV, it is used as the core operational amplifier in the detection amplifier circuit.

A method for detecting fire signs using a fire sign detection device, as shown in Figure 8, includes the following steps:

Step 1: The main control unit controls the suction fan to inhale the gas in the detection environment, and the gas enters the detection chamber of the housing through the suction inlet;

Step 2: The main control unit controls the two emission tubes to emit light beams sequentially in different emission modes at fixed time intervals. The light beams enter the photosensitive area after passing through the collimating lens. multiple reflection absorption;

The three different launch modes are as follows:

Emission mode 1: One emission tube emits a 50 ms beam;

Emission mode 2: Another emission tube emits a 50 millisecond beam;

Emission mode 3: two emission tubes emit 50 millisecond beams at the same time;

The fixed time interval is T0=30(ms) milliseconds

The transmission timing is 1; T0; 2; T0; 3; T0; the delay interval of 760 (ms) milliseconds;

1; T0; 2; T0; 3; T0; 760 (ms) millisecond delay interval;

Step 3: When the light beam passes through the photosensitive area, if the gas contains fire sign particles, it will scatter;

Step 4: Three photosensitive sensors receive the scattered beams, the extinction trap absorbs the parallel beams, and the parallel beams not absorbed by the extinction trap are emitted through the through hole of the extinction trap and then absorbed by the hood;

Step 5: Three photosensitive sensors receive the fire sign particles and the scattered light signal generated by the emitted light beam is amplified by the photoelectric detection amplifier circuit and then transmitted to the main control unit;

Step 6: The main control unit calculates the background increment of scattered light received by the three photosensitive sensors in different emission modes;

Each emission can receive 3 samples corresponding to the background incremental values of scattered light:

Transmit mode 1: AD11; AD12; AD13;

Transmitting mode 2: AD21; AD22; AD23;

Transmission mode 3: AD31; AD32; AD33;

Step 7: Calculate the ratio Kij of the background increments of scattered light received by the three photosensitive sensors in each emission mode, obtain the interval of the Kij value, and compare the interval of the Kij value with the Kij corresponding to the different types of fire symptom particles obtained in advance sampling Comparison of the standard interval of the value: if the interval of the Kij value falls into a certain standard interval, the current gas contains the fire sign particles corresponding to the standard interval, and it is determined whether there is a fire sign in the current detection environment according to the fire sign particles.

AD12/AD11=K121;

AD13/AD11=K131;

AD22/AD21=K221;

AD23/AD21=K231;

AD32/AD31=K321;

AD33/AD31=K331;

The fire symptom particles are dust, water vapor particles, diesel particles, PVC pyrolysis particles or wood pyrolysis particles.

The Kij values corresponding to different types of fire sign particles obtained by pre-sampling are as follows:

dust:

AD12/AD11=K121(2);

AD13/AD11=K131(5);

AD22/AD21=K221(8);

AD23/AD21=K231(1.2);

AD32/AD31=K321(7);

AD33/AD31 = K331 (6).

The standard interval of the Kij value corresponding to the dust is: [1.2,8].

Water Vapor Particles:

AD12/AD11=K121(6);

AD13/AD11=K131(3);

AD22/AD21=K221(4);

AD23/AD21=K231(3);

AD32/AD31=K321(4);

AD33/AD31=K331(1).

The standard interval of Kij value corresponding to water vapor particles is: [1,6].

Diesel particles:

AD12/AD11=K121(11);

AD13/AD11=K131(5);

AD22/AD21=K221(5);

AD23/AD21=K231(6);

AD32/AD31=K321(7);

AD33/AD31 = K331 (9).

The standard interval of Kij value corresponding to diesel particles is: [5,11].

PVC pyrolysis particles:

AD12/AD11=K121(1);

AD13/AD11=K131(5);

AD22/AD21=K221(2);

AD23/AD21=K231(6);

AD32/AD31=K321(2);

AD33/AD31 = K331 (3).

The standard interval of Kij value corresponding to PVC pyrolysis particles is: [1,6].

Wood pyrolysis particles:

AD12/AD11=K121(2);

AD13/AD11=K131(3);

AD22/AD21=K221(2);

AD23/AD21=K231(4);

AD32/AD31=K321(7);

AD33/AD31 = K331 (3).

The standard interval of Kij value corresponding to wood pyrolysis particles is: [2,7].

Claims (8)

1. A fire sign detection device, comprising: a housing, a hood, a suction fan, a main control unit and a detection assembly; The housing includes an upper cover and a base. The suction fan, the main control unit and the detection component are all arranged in the housing formed by the fastening of the upper cover and the base. There is an air suction inlet in the center of the upper cover, and a shading is installed at the suction inlet of the upper cover. cover; The main control unit is fixed at the base; the suction fan is located at the suction inlet of the upper cover, and the input end of the suction fan is connected to the fan control output end of the main control unit; A detection chamber with a labyrinth structure is arranged in the inner space of the housing, and a detection assembly is arranged in the detection chamber, including a light source module for emitting a detection beam and a scattering reception detection amplification circuit module for receiving a scattered signal generated by the irradiation of the detection beam; The light source module includes two emission tubes and two collimating lenses, and the input ends of the two emission tubes are respectively connected to the light source control output ends of the main control unit; It is characterized in that the detection chamber is provided with multiple exit pupil diaphragms, photosensitive areas and extinction light traps for multiple reflections and absorption of incompletely collimated paraxial stray light; The multiple exit pupil diaphragm is located behind the two collimating lenses; the exit pupil diaphragm is designed with a sharp angle of 30°; The photosensitive area is the place where the smoke particles in the gas pass through the channel of the detection chamber and the light beam emitted by the light source module intersects. The photosensitive area is cylindrical; the light source module, the scattering receiving detection amplifier circuit module, and the extinction optical trap are distributed on a spherical surface around the photosensitive area. ; The extinction light trap is an optical trap, which adopts the design method of optical dead space. After entering the extinction light trap, the light enters the dead space after multiple reflections; The light source module and the extinction light trap are symmetrically distributed to form a light source plane, the forward photosensitive sensor is arranged on one side of the extinction light trap, and the backward photosensitive sensor is arranged on the light source module side. 2. fire sign detection device according to claim 1, is characterized in that, described scattering receiving detection amplifying circuit module comprises three photosensitive sensors and three detecting amplifying circuits; The output end of each photosensitive sensor is respectively connected with each detecting amplifying circuit The input end and the output end of each detection amplifier circuit are respectively connected to the signal input end of the main control unit. 3 . The fire sign detection device according to claim 1 , wherein the light source module and the scattering receiving detection amplifying circuit module are mounted on the base in a clamping and fixing manner. 4 . 4 . The fire sign detection device according to claim 1 , wherein the housing is made of ABS engineering plastics, and the inner surface of the housing is covered with a shielding metal foil film to isolate external electromagnetic interference. 5. The fire sign detection device according to claim 1, wherein the photosensitive sensor adopts a sunken design, its installation angle forms a spatial angle with the emitted light beam, and the installation plane of the photosensitive sensor is lower than the plane of the light source. 6. The fire sign detection device according to claim 1, characterized in that a shading sheet is arranged between the photosensitive area and the suction fan. 7. The method for detecting fire signs using the fire sign detection device according to any one of claims 1-6, characterized in that: comprising the following steps: Step 1: The main control unit controls the suction fan to inhale the gas in the detection environment, and the gas enters the detection chamber of the housing through the suction inlet; Step 2: The main control unit controls the two emission tubes to sequentially emit light beams in different emission modes at fixed time intervals. The light beams enter the photosensitive area after passing through the collimating lens. multiple reflection absorption; The three different launch modes are as follows: Emission mode 1: One emission tube emits a 50 ms beam; Emission mode 2: Another emission tube emits a 50 millisecond beam; Emission mode 3: two emission tubes emit 50 millisecond beams at the same time; Step 3: When the light beam passes through the photosensitive area, if the gas contains fire sign particles, it will scatter; Step 4: Three photosensitive sensors receive the scattered beams, the extinction trap absorbs the parallel beams, and the parallel beams not absorbed by the extinction trap are emitted through the through hole of the extinction trap and then absorbed by the hood; Step 5: Three photosensitive sensors receive the fire sign particles and the scattered light signal generated by the emitted light beam is amplified by the photoelectric detection amplifier circuit and then transmitted to the main control unit; Step 6: The main control unit calculates the background increments received by the three photosensitive sensors in different emission modes; Step 7: Calculate the ratio Kij of each background increment received by the three photosensitive sensors in each emission mode, obtain the interval of the Kij value, and compare the interval of the Kij value with the Kij value corresponding to the different types of fire symptom particles obtained by pre-sampling Standard interval comparison: If the interval of the Kij value falls into a certain standard interval, the current gas contains fire sign particles corresponding to the standard interval, and the fire sign particles determine whether there is a fire sign in the current detection environment. 8. The method for detecting fire signs according to claim 7, wherein the fire sign particles are dust, water vapor particles, diesel particles, PVC pyrolysis particles or wood pyrolysis particles.