Multi-mode air-breathing smoke-sensing fire detector

Abstract

The utility model, which relates to the fire hazard detector field, discloses a multi-mode air-breathing type smoke-sensing fire hazard detector comprising a detection module, a main board, a state display part module, a blower fan module and a housing module. The utility model provides a multi-mode air-breathing smoke-sensing fire hazard detector, which performs composite analysis and calculation on sampled air through multiple detection means, and can greatly improve the accuracy of identifying different particle contents of the sampled air, thereby fundamentally reducing the false alarm rate and improving the detection accuracy. The air-breathing smoke-sensing fire detector can actively and uninterruptedly collect particles in the air of a monitored place by adopting an air-breathing mode for analysis, and can detect smoke and give an alarm very early and faster, so that the sensitivity is improved, and the false alarm rate is reduced.

Description

Technical Field

[0001] The utility model relates to the field of fire detectors, in particular to a multi-mode aspirating smoke fire detector. Background Art

[0002] Aspirating smoke detectors can detect smoke at the earliest stages of a fire, providing early warning. Compared to traditional smoke detectors, aspirating smoke detectors actively and continuously collect and analyze airborne particles in the monitored area, enabling much earlier and faster smoke detection and alarm activation. They offer advantages such as rapid alarm, simple operation, wide coverage, and a long service life. These advantages have led to their widespread adoption in numerous large-scale applications, including subway systems, large warehouses, computer rooms, bridges and tunnels, large supermarkets, cold storage facilities, and even outdoor locations such as forests. Aspirating smoke detectors boast exceptionally high sensitivity, with a detection range typically reaching 0.002% to 20% OBS / m, compared to the 3% to 5% OBS / m range of traditional smoke detectors.

[0003] Aspirating smoke detectors are generally designed to be highly sensitive, so slight interference can cause false alarms. When the air environment is poor, such as when there is a lot of dust, oil, other chemicals, or when there are a lot of water vapor particles in the air, aspirating smoke detectors may mistake these substances in the air for smoke, resulting in false alarms. Currently, most aspirating smoke detectors on the market use photoelectric smoke detection methods, using light sources such as LEDs and laser beams. The detection principle is to use LEDs and laser beams to illuminate the sampled air sucked into the detector, and then receive the scattered light generated by the smoke particles through a photosensitive sensor. The scattered light is analyzed to calculate the concentration of the smoke particles. When there are other particles such as dust, oil, water vapor, and chemicals in the air, these particles can also generate scattered light in the detector, causing the detector to generate false alarms. To solve the problem of false alarms, dust filters and condensate separators are generally added to the air intake end of the detector when laying the pipeline. This can reduce the incidence of false alarms, but in some scenes with heavy pollution, the effect is not very good.

[0004] Therefore, those skilled in the art provide a multi-mode aspirating smoke fire detector to solve the problems raised in the above background technology. Utility Model Content

[0005] The purpose of the present invention is to provide a multi-mode aspirating smoke fire detector to solve the problem that the aspirating smoke detector proposed in the above background technology is generally designed to have a relatively high sensitivity, and a slight interference may cause a false alarm. When the air environment is relatively poor, such as when there is a lot of dust, oil, other chemical substances, and a lot of water vapor particles in the air, the aspirating smoke fire detector may mistakenly judge these substances in the air as smoke, thereby generating a false alarm. At present, most of the aspirating smoke fire detectors on the market use a photoelectric smoke detection method, and the light sources used are LED and laser beams. The detection principle The principle is to use LED and laser beams to illuminate the sampled air sucked into the detector, and then use a photosensitive sensor to receive the scattered light generated by the smoke particles. The scattered light is analyzed to calculate the concentration of the smoke particles. When there are other dust, oil, water vapor, chemical substances and other particles in the air, these particles can also generate scattered light in the detector, causing the detector to generate false alarms. To solve the problem of false alarms, dust filters and condensate separators are generally added to the air intake end of the detector when laying the pipeline. This can reduce the incidence of false alarms, but in some scenes with heavier pollution, the effect is not very good.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A multi-mode aspirating smoke fire detector, comprising a detection module, a main board, a status display module, a fan module and a housing module;

[0008] Detection module: The smoke fire detector contains 1-8 detection modules, each of which includes 4 detection parts, namely the smoke detection part, the wind speed detection part, the humidity detection part and the chemical gas concentration detection part. Each detection module detects the sampled air of different pipes and performs detection independently of each other. The smoke detection part detects by photoelectric means, which contains dual light sources or multiple light sources with different wavelengths. No more than 4 light sources can be selected. The peak wavelength of the light source with the largest peak wavelength is recorded as λ1, and the peak wavelength of the light source with the smallest peak wavelength is recorded as λ2. The value of λ1-λ2 is above 200nm. The smoke detection part contains 1-4 photosensors. When there are 2-4 photosensors, the angle θ of the direction in which different photosensors receive scattered light relative to the emission direction of the same reference light source is different. The difference in the angle θ between each two photosensors is more than 20°.

[0009] As a preferred embodiment of the present invention: the communication part module: the communication part module includes an Ethernet communication part module and an RS485 communication part module;

[0010] Mainboard: The main controller module, power control module, data storage module and communication module constitute the mainboard.

[0011] As a preferred embodiment of the present invention: the smoke detection module has a light source, a photosensor, and an operational amplifier. The photosensor converts the reflected light generated by the sampled air into an electrical signal, which is then amplified by the operational amplifier. Dual light sources and multiple light sources can be selected, and less than 4 light sources can be selected, which can be a combination of red light LED, blue light LED, infrared light LED, ultraviolet light LED, and white light LED.

[0012] As a preferred embodiment of the present invention: the chemical gas concentration detection part can detect one or more of hydrogen, carbon monoxide, methane and ethylene VOC, and electrolyte vapor.

[0013] As a preferred embodiment of the present invention: the smoke detection module uses multiple light sources, and when using multiple photosensors, different photosensors receive reflections generated by different light sources, generate different electrical signals, and these electrical signals are subjected to combined operations such as weighted subtraction and ratio.

[0014] As a preferred embodiment of the present invention: the humidity detection part detects the humidity of the sampled air. If the humidity is very low, the calculation of the sampled air particle concentration will be little affected by water vapor and condensation. If the humidity is very high, the calculation of the sampled air particle concentration needs to consider the influence of water vapor and condensation. The algorithm for calculating the large-diameter particle concentration can be adjusted and the threshold for large-diameter particle alarm can be increased.

[0015] As a preferred embodiment of the present invention: the chemical gas concentration detection part detects the concentration of a specific gas in the sampled air. If the concentration of the specific gas is detected to be on an upward trend and exceeds the standard, the detector alarm strategy needs to be adjusted to be more sensitive. If the concentration of the specific gas is normal or very low, the detector alarm strategy can be adjusted to normal according to the actual air conditions.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] This utility model discloses a multi-mode aspirating smoke fire detector. It proposes a multi-mode aspirating smoke fire detector. Through a variety of detection methods, it performs a composite analysis and calculation on the sampled air, which can greatly improve the accuracy of identifying different particle contents in the sampled air, thereby fundamentally reducing the false alarm rate. The aspirating smoke fire detector can actively and continuously collect particles in the air of the monitored place by aspiration for analysis, and can detect smoke very early and quickly, and issue an alarm. To improve sensitivity and reduce the false alarm rate, we adopt multi-mode detection and adopt multiple methods for comprehensive judgment. As for the light source, red and blue light sources can be selected. The peak wavelength of red light LED is generally around 720nm, and the peak wavelength of blue light LED is generally around 470nm. When the particle size of smoke particles is in the range of 0.1-10μm, Mie scattering is used to calculate the scattered light intensity. When the particle size is in the range of 0.01-0.1μm, its scattering model gradually approaches Rayleigh scattering. The smaller the particle size, for example, the particle size is less than 0.015μm. When the light intensity is larger, Rayleigh scattering is more suitable to calculate the scattered light intensity. The scattered light intensity of Mie scattering is inversely proportional to the square of the wavelength, and the scattered light intensity of Rayleigh scattering is inversely proportional to the fourth power of the wavelength. Since blue light sources are more sensitive to tiny smoke particles, the use of red light sources in actual applications can better detect changes in large smoke particles, and the use of blue light sources can better detect changes in tiny smoke particles. This is very important for fire detection, because the smoke particles produced by fire in the brewing and germination stages will be smaller than the particles of later combustion products. Therefore, red and blue light sources have great advantages for very early fire detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent from the detailed description of the non-limiting embodiments with reference to the following drawings:

[0019] Figure 1 This is a structural diagram of a multi-mode aspirating smoke fire detector.

[0020] Figure 2 The figure is a schematic diagram of the structure of the detection part of a multi-mode aspirating smoke fire detector.

[0021] Figure 3 The figure is a schematic diagram of the structure of the smoke detection part scheme A in a multi-mode aspirating smoke fire detector.

[0022] Figure 4 This is a structural diagram of the smoke detection scheme B in a multi-mode aspirating smoke fire detector. DETAILED DESCRIPTION

[0023] In an embodiment of the present invention, a multi-mode aspirating smoke fire detector includes a detection module, a main board, a status display module, a fan module and a housing module;

[0024] Detection module: The smoke fire detector contains 1-8 detection modules, each of which includes 4 detection parts, namely the smoke detection part, the wind speed detection part, the humidity detection part and the chemical gas concentration detection part. Each detection module detects the sampled air of different pipes and performs detection independently of each other. The smoke detection part detects by photoelectric means, which contains dual light sources or multiple light sources with different wavelengths. No more than 4 light sources can be selected. The peak wavelength of the light source with the largest peak wavelength is recorded as λ1, and the peak wavelength of the light source with the smallest peak wavelength is recorded as λ2. The value of λ1-λ2 is above 200nm. The smoke detection part contains 1-4 photosensors. When there are 2-4 photosensors, the angle θ of the direction in which different photosensors receive scattered light relative to the emission direction of the same reference light source is different. The difference in the angle θ between each two photosensors is more than 20°.

[0025] Working method of aspirating smoke fire detector: different wavelengths of light have different scattering characteristics for different types of particles, such as dust, oil, water vapor, and chemicals, and the scattered light intensity is different. Let the light source be L(i), the photosensor be S(j), and the angle of the direction in which the scattered light is received by the photosensor S(j) relative to the emission direction of the light source L(i) is θ(i,j). The induced electrical signal generated by the scattered light generated by L(i) irradiating the sampled air on S(j) is recorded as f(L(i), S(j), θ(i,j)), where i and j are natural numbers from 1 to 4, L(1)-L(4) represent 4 light sources with different wavelengths, S(1)-S(4) represent 4 photosensors, θ(1,1)-θ(1,4) represent the receiving angles of the 4 photosensors relative to the emitting light source L(1), and θ(2,1)-θ(4,4) have the same meaning. When using two light sources and one photosensor, the angle can be calculated by f(L(1), S(1), θ(1,1)) - f(L(2),S(1),θ(2,1)), f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)) , that is, the difference and ratio of the weighted two electrical signals and the amplified electrical signals, the result of the combination of the difference and the ratio can be used to identify the current state of the sampled air containing particles, the change in the content of a specific type of particles, and the different types of particles have different reflection characteristics for the same light at different angles; when using two light sources and two photosensors, it can be determined by f(L(1),S(1),θ(1,1)) - f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) - f(L(2),S(2),θ(2,2)), f(L(1),S(1),θ(1.1)) - f(L(2),S(2),θ(2,2)), and the values of f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) / f(L(2),S(2),θ(2,2)), and f(L(1),S(1),θ(1,1)) / f(L(2),S(2),θ(2,2)) are used to comprehensively judge the condition of particles in the air. This can be judged comprehensively based on multiple sets of data, thereby improving the reliability of the judgment and reducing the false alarm rate.

[0026] A multi-mode aspirating smoke fire detector is proposed. Through a variety of detection methods, the sampled air is subjected to composite analysis and calculation, which can greatly improve the accuracy of identifying the different particle contents in the sampled air, thereby fundamentally reducing the false alarm rate. The aspirating smoke fire detector can actively and continuously collect the particles in the air of the monitored place by aspiration for analysis, and can detect smoke very early and quickly, and issue an alarm. In order to improve sensitivity and reduce the false alarm rate, we adopt multi-mode detection and use multiple methods to make comprehensive judgments.

[0027] Solution 1: The detection section includes a blue LED (wavelength approximately 470nm) L(1), a red LED (wavelength approximately 720nm) L(2), a photosensor S(1), a humidity detection section, and a chemical gas concentration detection section. The angle θ(1,1) = 135° relative to the emission direction of the blue LED and the angle θ(2,1) = 135° relative to the emission direction of the red LED are received by the photosensor. The blue LED and the red LED light sources are irradiated alternately. The value of f(L(1), S(1), θ(1,1)) / f(L(2), S(1), θ(2,1)) is used to determine the presence of particles in the air. When the ratio is relatively large, the content of smaller smoke particles is high. When the ratio is relatively small, the content of larger dust particles is high. The humidity sensor calculates the humidity of the sampled air. If the humidity value is high, the alarm threshold for large-diameter particles can be raised. Furthermore, a weighted calculation is performed on the smoke concentration formula to eliminate the possible influence of water vapor and prevent false alarms. The carbon monoxide sensor calculates the carbon monoxide content of the sampled air. If the concentration of a specific gas is detected to be rising or exceeding the standard, the alarm threshold can be lowered to increase product sensitivity. If the concentration of a specific gas is normal or very low, the system raises the alarm threshold to prevent false alarms.

[0028] Communication module: The communication module includes Ethernet and RS485 communication modules. The mainboard consists of a main controller module, power control module, data storage module, and communication module. The smoke detection module includes a light source, photosensor, and operational amplifier. The photosensor converts reflected light from the sampled air into an electrical signal, which is then amplified by the operational amplifier. Dual or multiple light sources are available, with up to four light sources available, including combinations of red, blue, infrared, ultraviolet, and white LEDs. The chemical gas concentration detection module can detect one or more of hydrogen, carbon monoxide, methane, ethylene (VOC), and electrolyte vapor. When the smoke detection module uses multiple light sources and multiple photosensors, each photosensor receives reflections from different light sources, generating different electrical signals. These signals are then processed through weighted subtraction and ratio calculations to identify the current particle content in the sampled air and changes in the concentration of specific particle types. The humidity detection section detects the humidity of the sampled air. If the humidity is very low, the particle concentration calculation of the sampled air will be minimally affected by water vapor and condensation. If the humidity is very high, the effects of water vapor and condensation need to be considered. The algorithm for calculating the concentration of large-diameter particles can be adjusted, and the threshold for large-diameter particle alarms can be raised to prevent false alarms. The chemical gas concentration detection section detects the concentration of specific gases in the sampled air. If the concentration of a specific gas is detected to be on an upward trend or exceeds the standard, the detector alarm strategy needs to be adjusted to be more sensitive. If the concentration of a specific gas is normal or very low, the detector alarm strategy can be adjusted to normal according to the actual air conditions to prevent false alarms.

[0029] For the light source, you can choose red and blue light sources. The peak wavelength of red LED is generally around 720nm, and the peak wavelength of blue LED is generally around 470nm. When the particle size of smoke particles is at the level of 0.1-10μm, Mie scattering is used to calculate the scattered light intensity; when the particle size is at the level of 0.01-0.1μm, its scattering model gradually approaches Rayleigh scattering. The smaller the particle size, for example, when the particle size is less than 0.015μm, the more suitable Rayleigh scattering is to calculate the scattered light intensity. The scattered light intensity of Mie scattering is inversely proportional to the square of the wavelength, and the scattered light intensity of Rayleigh scattering is inversely proportional to the square of the wavelength. The power is inversely proportional. Since blue light sources are more sensitive to tiny smoke particles, red light sources can better detect changes in large smoke particles in actual applications, and blue light sources can better detect changes in tiny smoke particles. This is very important for fire detection, because the smoke particles produced by fire in the brewing and germination stages are smaller than the particles of later combustion products. Therefore, red and blue light sources have great advantages in very early fire detection.

[0030] Solution 2: The detection section includes a blue LED (wavelength approximately 470nm) L(1), a red LED (wavelength approximately 720nm) L(2), two photosensors S(1) and S(2), a humidity detection section, and a chemical gas concentration detection section. The angle of the scattered light received by photosensor S(1) relative to the emission direction of the blue LED is θ(1,1) = 45°, and the angle of the scattered light received by photosensor S(2) relative to the emission direction of the blue LED is θ(1,2) = 135°, and the angle of the scattered light received by photosensor S(2) relative to the emission direction of the red LED is θ(2,2) = 45°. The blue LED and the red LED light sources are irradiated alternately. The values of f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) / f(L(2),S(2),θ(2,2)), and f(L(1),S(1),θ(1,1)) / f(L(2),S(2),θ(2,2)) are used to comprehensively judge the presence of particles in the air. Based on Scheme 1, Scheme 2 makes a comprehensive judgment based on multiple sets of data, which improves the reliability of the judgment and reduces the false alarm rate. The humidity value of the sampled air is calculated by a humidity sensor. If the humidity value is large, the alarm threshold for large-diameter particles can be increased. Alternatively, a weighted calculation is performed on the smoke concentration calculation formula to eliminate the possible influence of water vapor and prevent false alarms. The carbon monoxide content of the sampled air is calculated by the carbon monoxide sensor. If the concentration of a specific gas is detected to be on an upward trend or exceeds the standard, the alarm threshold can be lowered to increase the sensitivity of the product. If the concentration of a specific gas is normal or very low, the system will raise the alarm threshold to prevent false alarms.

[0031] The operating principle of the present invention is as follows: The multi-mode aspirating smoke fire detector comprises a detection module, a main board, a status display module, a fan module, and a housing module. The smoke detection module comprises a light source, a photosensor, and an operational amplifier. The photosensor converts the reflected light generated by the sampled air into an electrical signal, which is then amplified by the operational amplifier. Dual or multiple light sources, up to four, can be used, and can be a combination of red LEDs, blue LEDs, infrared LEDs, ultraviolet LEDs, and white LEDs. The chemical gas concentration detection section can detect one or more of hydrogen, carbon monoxide, methane and ethylene (VOC), and electrolyte vapor. When the smoke detection module uses multiple light sources and multiple photosensors, different photosensors receive reflections from different light sources, generating different electrical signals. These electrical signals are then processed through weighted subtraction and ratio calculations to identify the particle content in the sampled air and changes in the content of specific types of particles. The humidity detection section detects the humidity of the sampled air. If the humidity is very low, the particle concentration calculation of the sampled air will be minimally affected by water vapor and condensation. If the humidity is very high, the effects of water vapor and condensation need to be considered. The algorithm for calculating the concentration of large-diameter particles can be adjusted, and the threshold for large-diameter particle alarms can be raised to prevent false alarms. The chemical gas concentration detection section detects the concentration of specific gases in the sampled air. If the concentration of a specific gas is detected to be on an upward trend or exceeds the standard, the detector alarm strategy needs to be adjusted to be more sensitive. If the concentration of a specific gas is normal or very low, the detector alarm strategy can be adjusted to normal according to the actual air conditions to prevent false alarms.

[0032] Detection module: The smoke fire detector contains 1-8 detection modules, each of which includes 4 detection parts, namely the smoke detection part, the wind speed detection part, the humidity detection part and the chemical gas concentration detection part. Each detection module detects the sampled air of different pipes and performs detection independently of each other. The smoke detection part detects by photoelectric means, which contains dual light sources or multiple light sources with different wavelengths. No more than 4 light sources can be selected. The peak wavelength of the light source with the largest peak wavelength is recorded as λ1, and the peak wavelength of the light source with the smallest peak wavelength is recorded as λ2. The value of λ1-λ2 is above 200nm. The smoke detection part contains 1-4 photosensors. When there are 2-4 photosensors, the angle θ of the direction in which different photosensors receive scattered light relative to the emission direction of the same reference light source is different. The difference in the angle θ between each two photosensors is more than 20°.

[0033] Communication module: The communication module includes the Ethernet communication module and the RS485 communication module. Mainboard: The main controller module, power control module, data storage module, and communication module constitute the mainboard. Working method of aspirating smoke detector: Light of different wavelengths has different scattering characteristics for different types of particles, such as dust, oil, water vapor, and chemicals, and the scattered light intensity is different. Let the light source be L(i), the photosensor be S(j), and the angle of the direction in which the scattered light is received by the photosensor S(j) relative to the emission direction of the light source L(i) is θ(i, j). The induced electrical signal generated by the scattered light generated by L(i) irradiating the sampled air on S(j) is recorded as f(L(i), S(j), θ(i, j)), where i and j are natural numbers from 1 to 4, L(1)-L(4) represent four light sources with different wavelengths, S(1)-S(4) represent four photosensors, θ(1,1)-θ(1,4) represent the receiving angles of the four photosensors relative to the emitting light source L(1), and θ(2,1)-θ(4,4) have the same meaning. When using two light sources and one photosensor, it can be expressed by f(L(1), S(1), θ(1,1)). - f(L(2),S(1),θ(2,1)), f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)), that is, the difference and ratio of the weighted two electrical signals and the amplified electrical signals. The result of the combination of the difference and the ratio can be used to identify the particle content in the current sampled air, the change in the content of a specific type of particles, and the different types of particles have different reflection characteristics for the same light at different angles. When using two light sources and two photosensors, the results can be obtained by f(L(1),S(1),θ(1,1)) - f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) - f(L(2),S(2),θ(2,2)), f(L(1),S(1),θ(1.1)) - f(L(2),S(2),θ(2,2)), and the values of f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) / f(L(2),S(2),θ(2,2)), and f(L(1),S(1),θ(1,1)) / f(L(2),S(2),θ(2,2)) are used to comprehensively judge the condition of particles in the air. This can be judged comprehensively based on multiple sets of data, thereby improving the reliability of the judgment and reducing the false alarm rate.

[0034] A multi-mode aspirating smoke fire detector is proposed. Through a variety of detection methods, the sampled air is subjected to composite analysis and calculation, which can greatly improve the accuracy of identifying the different particle contents in the sampled air, thereby fundamentally reducing the false alarm rate. The aspirating smoke fire detector can actively and continuously collect the particles in the air of the monitored place by aspiration for analysis, and can detect smoke very early and quickly, and issue an alarm. In order to improve sensitivity and reduce the false alarm rate, we adopt multi-mode detection and use multiple methods to make comprehensive judgments.

[0035] Solution 1: The detection section includes a blue LED (wavelength approximately 470nm) L(1), a red LED (wavelength approximately 720nm) L(2), a photosensor S(1), a humidity detection section, and a chemical gas concentration detection section. The angle θ(1,1) = 135° relative to the emission direction of the blue LED and the angle θ(2,1) = 135° relative to the emission direction of the red LED are received by the photosensor. The blue LED and the red LED light sources are irradiated alternately. The value of f(L(1), S(1), θ(1,1)) / f(L(2), S(1), θ(2,1)) is used to determine the presence of particles in the air. When the ratio is relatively large, the content of smaller smoke particles is high. When the ratio is relatively small, the content of larger dust particles is high. The humidity sensor calculates the humidity of the sampled air. If the humidity value is high, the alarm threshold for large-diameter particles can be raised. Furthermore, a weighted calculation is performed on the smoke concentration formula to eliminate the possible influence of water vapor and prevent false alarms. The carbon monoxide sensor calculates the carbon monoxide content of the sampled air. If the concentration of a specific gas is detected to be rising or exceeding the standard, the alarm threshold can be lowered to increase product sensitivity. If the concentration of a specific gas is normal or very low, the system raises the alarm threshold to prevent false alarms.

[0036] For the light source, you can choose red and blue light sources. The peak wavelength of red LED is generally around 720nm, and the peak wavelength of blue LED is generally around 470nm. When the particle size of smoke particles is at the level of 0.1-10μm, Mie scattering is used to calculate the scattered light intensity; when the particle size is at the level of 0.01-0.1μm, its scattering model gradually approaches Rayleigh scattering. The smaller the particle size, for example, when the particle size is less than 0.015μm, the more suitable Rayleigh scattering is to calculate the scattered light intensity. The scattered light intensity of Mie scattering is inversely proportional to the square of the wavelength, and the scattered light intensity of Rayleigh scattering is inversely proportional to the square of the wavelength. The power is inversely proportional. Since blue light sources are more sensitive to tiny smoke particles, red light sources can better detect changes in large smoke particles in actual applications, and blue light sources can better detect changes in tiny smoke particles. This is very important for fire detection, because the smoke particles produced by fire in the brewing and germination stages are smaller than the particles of later combustion products. Therefore, red and blue light sources have great advantages in very early fire detection.

[0037] Solution 2: The detection section includes a blue LED (wavelength approximately 470nm) L(1), a red LED (wavelength approximately 720nm) L(2), two photosensors S(1) and S(2), a humidity detection section, and a chemical gas concentration detection section. The angle of the scattered light received by photosensor S(1) relative to the emission direction of the blue LED is θ(1,1) = 45°, and the angle of the scattered light received by photosensor S(2) relative to the emission direction of the blue LED is θ(1,2) = 135°, and the angle of the scattered light received by photosensor S(2) relative to the emission direction of the red LED is θ(2,2) = 45°. The blue LED and the red LED light sources are irradiated alternately. The values of f(L(1),S(1),θ(1,1)) / f(L(2),S(1),θ(2,1)), f(L(1),S(2),θ(1,2)) / f(L(2),S(2),θ(2,2)), and f(L(1),S(1),θ(1,1)) / f(L(2),S(2),θ(2,2)) are used to comprehensively judge the presence of particles in the air. Based on Scheme 1, Scheme 2 makes a comprehensive judgment based on multiple sets of data, which improves the reliability of the judgment and reduces the false alarm rate. The humidity value of the sampled air is calculated by a humidity sensor. If the humidity value is large, the alarm threshold for large-diameter particles can be increased. Alternatively, a weighted calculation is performed on the smoke concentration calculation formula to eliminate the possible influence of water vapor and prevent false alarms. The carbon monoxide content of the sampled air is calculated by the carbon monoxide sensor. If the concentration of a specific gas is detected to be on an upward trend or exceeds the standard, the alarm threshold can be lowered to increase the sensitivity of the product. If the concentration of a specific gas is normal or very low, the system will raise the alarm threshold to prevent false alarms.

[0038] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent substitutions and changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-mode aspirating smoke fire detector, characterized in that: The multi-mode aspirating smoke fire detector comprises a detection module, a main board, a status display module, a fan module and a housing module; Detection module: The smoke fire detector contains 1-8 detection modules, each detection module includes 4 detection parts, namely smoke detection part, wind speed detection part, humidity detection part and chemical gas concentration detection part. Each detection module detects the sampled air of different pipes and performs detection independently of each other; the smoke detection part detects by photoelectric means, which contains dual light sources or multiple light sources with different wavelengths, and no more than 4 light sources are selected. The peak wavelength of the light source with the largest peak wavelength is recorded as λ1, and the peak wavelength of the light source with the smallest peak wavelength is recorded as λ2. The value of λ1-λ2 is above 200nm. The smoke detection part contains 1-4 photosensors. When there are 2-4 photosensors, the angle θ of the direction of receiving scattered light relative to the emission direction of the same reference light source is different for different photosensors, and the difference in angle θ between each two photosensors is more than 20°.

2. The multi-mode aspirating smoke detector according to claim 1, characterized in that: Also includes: Communication part module, the communication part module includes Ethernet communication part module and RS485 communication part module; Mainboard: The main controller module, power control module, data storage module and communication module constitute the mainboard.

3. The multi-mode aspirating smoke detector according to claim 1, characterized in that: Also includes: Smoke Detection module, the smoke detection module has a light source, a photosensor, and an operational amplifier. The photosensor converts the reflected light generated by the sampled air into an electrical signal, which is then amplified by the operational amplifier. Dual light sources and multiple light sources can be selected with less than 4 light sources, which can be combined among red LED, blue LED, infrared LED, ultraviolet LED, and white LED.

4. The multi-mode aspirating smoke detector according to claim 1, characterized in that: The chemical gas concentration detection part can detect one or more of hydrogen, carbon monoxide, methane and ethylene VOC, and electrolyte vapor.

5. The multi-mode aspirating smoke fire detector according to claim 3, characterized in that: The smoke detection module uses multiple light sources and multiple photosensors. Different photosensors receive reflections from different light sources and generate different electrical signals. These electrical signals are subjected to weighted subtraction and ratio combination operations.

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