A point-type smoke detection method and detector capable of excluding interference from aerosol interference

Abstract

The present invention discloses a point-type smoke detection method and detector capable of excluding the interference of interfering aerosols, belonging to the technical field of fire alarm; wherein, the detector includes an optical chamber, a first to a third light source and a photoelectric converter; the first light source is used for emitting a first blue light signal and a first infrared light signal; the second light source is used for emitting a second blue light signal; the third light source is used for emitting a second infrared light signal; the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter; the detection method includes: using four-way light sources to respectively emit a first blue light signal, a first infrared light signal, a second blue light signal and a second infrared light signal, and based on the change values and slopes of the scattered light intensities of each light signal, combined with the carbon monoxide concentration, it is possible to accurately distinguish fire smoke and interfering aerosols, greatly reducing the false alarm rate of fire detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire alarm, and more specifically, relates to a smoke fire detection method and a detector. Background Art

[0002] In fire detection, smoke is the most sensitive fire detection feature; in the initial stage of a fire, a fire detector can quickly respond, effectively reducing the difficulty of fire extinguishing and extending the escape time of trapped people, and reducing casualties and property losses. Currently, the most widely used is the point-type photoelectric smoke fire detector. The point-type photoelectric smoke fire detector has a simple structure, low cost, and is easy to maintain, and does not pollute the environment, being deeply loved by the market.

[0003] A fire detector is an important part of a fire prevention system. With the rapid development of semiconductor technology and optoelectronic processes in recent years, the point-type photoelectric smoke fire detector has become the mainstream product in the market. However, the point-type photoelectric smoke fire detector still has defects: the point-type photoelectric smoke fire detector judges the fire situation based on the intensity of the scattered light of smoke particles, but non-fire typical interference sources, such as: cooking fumes, dust, water vapor, will also trigger false alarms of the point-type photoelectric smoke fire detector; indoors, the cooking fumes generated during the cooking process are the main reason for the false alarms of the point-type photoelectric smoke fire detector. Cooking fumes are mainly composed of water vapor, oxygen-containing organic compounds, trace CO gas, etc. These substances will also cause light scattering to make the point-type photoelectric smoke fire detector reach the alarm condition, resulting in false alarms of the point-type photoelectric smoke fire detector. This defect in principle has become a problem and bottleneck that has restricted traditional smoke detection technology for many years. Studying the characteristics and methods of identifying fire smoke and non-fire aerosols to correctly sense the pyrolysis and smoldering smoke in the early stage of a fire has become an urgent technical problem in this field. Summary of the Invention

[0004] In view of the above defects or improvement requirements of the prior art, the present invention provides a smoke fire detection method and a detector, which are used to solve the technical problem of a relatively high false alarm rate in existing fire detection technology.

[0005] To achieve the above object, in a first aspect, the present invention provides a smoke fire detection method, including:

[0006] Obtaining the scattered light intensity value P of the first blue light signal emitted by the current first light source through a photoelectric converter B1 and the scattered light intensity value P of the first infrared light signal I1 and the scattered light intensity value P of the second blue light signal emitted by the second light source B2 and the scattered light intensity value P of the second infrared light signal emitted by the third light source I2, subtract it from the corresponding background value and then perform filtering to obtain the corresponding change value of the scattered light intensity ΔP B1 , ΔP I1 , ΔP B2 , ΔP I2 ;

[0007] When ΔP B1 is greater than or ΔP I1 is greater than or ΔP B2 is greater than or ΔP I2 is greater than , calculate the slopes K B1 , K I1 , K B2 , K I2 ;

[0008] When K B1 , K I1 , K B2 , K I2 are all greater than the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is in the range of [R TH1 , R TH2 and the current concentration of carbon monoxide N CO is greater than or equal to N TH1 , then it is determined that there is black smoke from a fire and an alarm is issued;

[0009] When K B1 , K I1 , K B2 , K I2 are all less than or equal to the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is in the range of [R TH2 , R TH3 and the current concentration of carbon monoxide N CO is greater than or equal to N TH1 , then it is determined that there is white smoke from a fire and an alarm is issued;

[0010] Among them, K TH , R TH1 , R TH2 , R TH3 , N TH1 are all preset threshold values, and R TH1 < R TH2 < R TH3 ; P B1 , PI1 , P B2 , P I2 The background values of P are the scattered light intensity values of the first blue light signal respectively obtained by the photoelectric converter in a smokeless environment. The scattered light intensity value of the first infrared light signal The scattered light intensity value of the second blue light signal and the scattered light intensity value of the second infrared light signal

[0011] The first light source, the second light source, and the third light source are all LED light sources, and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, while the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter.

[0012] Further preferably, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both within the range of [40°, 90°); the angles between the emission directions of the second blue light signal and the second infrared light signal and the receiving direction of the photoelectric converter are both within the range of (90°, 140°], and the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is greater than the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter.

[0013] Further preferably, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both 40°; the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is 140°; the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter is 100°.

[0014] Further preferably, when ΔP B1 is greater than or ΔP I1 is greater than or ΔP B2 is greater than or ΔP I2 is greater than , for the first blue light signal, the first infrared light signal, the second blue light signal, and the second infrared light signal respectively, calculate the difference between the current scattered light intensity change value and the scattered light intensity change value at each moment within the previous preset time period, and average all the differences to obtain the slopes K B1 , K I1 , K B2 , K I2 .

[0015] Further preferably, the above smoke fire detection method further includes:

[0016] When K B1 、K I1 、K B2 、K I2 are all greater than the preset threshold value K TH 、and the ratio of ΔP I1 to ΔP B2 is not within the range of [R TH1 , R TH2 , and the current concentration N of carbon monoxide CO is less than N TH1 , it is determined as dust and no alarm is issued;

[0017] When K B1 、K I1 are all greater than the preset threshold value K TH 、and K B2 、K I2 are all less than or equal to the preset threshold value K TH 、and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH3 , R TH4 , and the current concentration N of carbon monoxide CO is greater than or equal to N TH2 , it is determined as lampblack and no alarm is issued;

[0018] When K B1 、K I1 are all greater than the preset threshold value K TH 、and K B2 、K I2 are all less than or equal to the preset threshold value K TH 、and the ratio of ΔP I1 to ΔP B2 is not within the range of [R TH3 , R TH4 , and the current concentration N of carbon monoxide CO is less than N TH2 , it is determined as water vapor and no alarm is issued;

[0019] Among them, R TH4 、N TH2 are both preset threshold values, and R TH4 >R TH3 ,N TH2 <N TH1 .

[0020] In a second aspect, the present invention provides a smoke fire detector, including: a controller, an optical chamber, and a first light source, a second light source, a third light source, and a photoelectric converter disposed in the optical chamber;

[0021] The first light source, the second light source, and the third light source are all LED light sources; the first light source is used to emit a first blue light signal and a first infrared light signal; the second light source is used to emit a second blue light signal; the third light source is used to emit a second infrared light signal; and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter;

[0022] The controller is used to execute the smoke fire detection method provided in the first aspect of the present invention.

[0023] Further preferably, the above-mentioned smoke fire detector further includes a carbon monoxide sensor for real-time sensing of the concentration N of carbon monoxide in the current environment CO 。

[0024] Further preferably, the above-mentioned smoke fire detector further includes a temperature sensor for real-time sensing of the ambient temperature.

[0025] Generally speaking, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0026] 1. The present invention provides a smoke fire detection method that uses four light sources to respectively emit a first blue light signal, a first infrared light signal, a second blue light signal, and a second infrared light signal, and receives scattered light intensity signals at multiple angles. Considering that the particle size distribution and refractive index and other specific physical parameters of real fire smoke and non-fire interference aerosols can be calculated from the scattered light intensity information under the above optical paths, based on the change values and slopes of the scattered light intensities of each optical signal, combined with the concentration N of carbon monoxide CO , it is possible to accurately distinguish fire smoke and non-fire interference aerosols, thereby eliminating the interference of non-fire typical interference aerosols and greatly reducing the false alarm rate of fire detection.

[0027] 2. Further, in the smoke fire detection method provided by the present invention, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both within the range of [40°, 90°); the angles between the emission directions of the second blue light signal and the second infrared light signal and the receiving direction of the photoelectric converter are both within the range of (90°, 140°], and the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is greater than the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter. Among them, the acute-angle scattered light has a high signal-to-noise ratio and good anti-interference performance, and the obtuse-angle scattered light carries rich information such as the refractive index of the aerosol, which helps to distinguish the types of aerosols, further reducing the false alarm rate of fire detection.

[0028] 3. Further, in the smoke fire detection method provided by the present invention, considering that different aerosols have different inherent physical parameters, which will lead to different changing trends of the scattering signals of each optical path after entering the detector's optical chamber, by processing the scattered light signals through the method provided by the present invention, typical interference sources such as cooking fume, dust, and water vapor can be accurately distinguished, and real fire smoke and various non-fire aerosols can be more accurately identified.

[0029] 4. Further, in the smoke fire detector provided by the present invention, since various physical parameters of the aerosol entering the optical chamber can be obtained, early fire smoke can be accurately identified and its type information can be obtained without reducing the detector's sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a top view schematic diagram of a smoke detector structure provided by an embodiment of the present invention;

[0031] Figure 2 It is a three-dimensional structure schematic diagram of the smoke detector provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] To achieve the above objectives, in the first aspect, the present invention provides a smoke fire detection method, including:

[0034] Obtaining the scattered light intensity value P of the first blue light signal emitted by the current first light source and the scattered light intensity value P of the first infrared light signal through a photoelectric converter B1 and the scattered light intensity value P of the second blue light signal emitted by the second light source I1 and the scattered light intensity value P of the second infrared light signal emitted by the third light source B2 and subtracting them from the corresponding background values and then performing filtering to obtain the corresponding scattered light intensity change values ΔP I2 , ΔP B1 , ΔP I1 , ΔP B2 , ΔP I2 ;

[0035] When ΔP B1 is greater than or ΔP I1 is greater than or ΔP B2Greater than or ΔP I2 Greater than When this is the case, the slopes K B1 , K I1 , K B2 , K I2 ; are calculated for each scattered light signal respectively; In an alternative embodiment, for the first blue light signal, the first infrared light signal, the second blue light signal, and the second infrared light signal respectively, the difference between the current scattered light intensity change value and the scattered light intensity change value at the previous moment is calculated to obtain the slopes K B1 , K I1 , K B2 , K I2 of each scattered light signal. In another alternative embodiment, for the first blue light signal, the first infrared light signal, the second blue light signal, and the second infrared light signal respectively, the difference between the current scattered light intensity change value and the scattered light intensity change value at each moment within the previous preset time period (which is 10 s in this embodiment) is calculated, and all the differences are averaged to obtain the slopes K B1 , K I1 , K B2 , K I2 .

[0036] When K B1 , K I1 , K B2 , K I2 are all greater than the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH1 , R TH2 , and the current concentration N of carbon monoxide CO is greater than or equal to N TH1 , then it is determined that there is black smoke from a fire and an alarm is issued;

[0037] When K B1 , K I1 , K B2 , K I2 are all less than or equal to the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH2 , R TH3 , and the current concentration N of carbon monoxide CO is greater than or equal to N TH1 , then it is determined that there is white smoke from a fire and an alarm is issued;

[0038] Among them, K TH , RTH1 , R TH2 , R TH3 , N TH1 are all preset threshold values, and R TH1 < R TH2 < R TH3 ; P B1 , P I1 , P B2 , P I2 The background values of P are respectively the scattered light intensity values of the first blue light signal obtained through the photoelectric converter in a smokeless environment The scattered light intensity value of the first infrared light signal The scattered light intensity value of the second blue light signal

[0039] The first light source, the second light source, and the third light source are all LED light sources, and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with the receiving direction of the photoelectric converter

[0040] In an alternative embodiment, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both within the range of [40°, 90°); the angles between the emission directions of the second blue light signal and the second infrared light signal and the receiving direction of the photoelectric converter are both within the range of (90°, 140°], and the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is greater than the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter

[0041] Preferably, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both 40°; the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is 140°; the angle between the emission direction of the second infrared signal and the receiving direction of the photoelectric converter is 100°

[0042] In an alternative embodiment, in addition to being able to identify the above-mentioned fire black smoke and fire white smoke, a detection method capable of identifying interfering aerosols including cooking fumes, dust, water vapor, etc. is also provided. Specifically, the above-mentioned smoke fire detection method further includes

[0043] When K B1 , K I1 , K B2 , K I2 are all greater than the preset threshold value K TH , and ΔPI 1 and ΔPB2 The ratio is not within the range of [R TH1 , R TH2 , and the current concentration N of carbon monoxide CO is less than N TH1 . In this case, it is determined as dust and no alarm is issued;

[0044] When both K B1 and K I1 are greater than the preset threshold value K TH , and both K B2 and K I2 are less than or equal to the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH3 , R TH4 , and the current concentration N of carbon monoxide CO is greater than or equal to N TH2 . In this case, it is determined as lampblack and no alarm is issued;

[0045] When both K B1 and K I1 are greater than the preset threshold value K TH , and both K B2 and K I2 are less than or equal to the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is not within the range of [R TH3 , R TH4 , and the current concentration N of carbon monoxide CO is less than N TH2 . In this case, it is determined as water vapor and no alarm is issued;

[0046] Among them, both R TH4 and N TH2 are preset threshold values, and R TH4 > R TH3 , N TH2 < N TH1 .

[0047] It should be noted that in the early stage of a fire, the present invention preliminarily determines the type of smoke using the slope of the light scattering signal, and then completes the final classification of the smoke through the ratio and the concentration of the carbon monoxide sensor, greatly reducing the false alarm rate of the smoke detector. Considering that, for example, in a kitchen scenario, lampblack is one of the main interference sources causing false alarms of the smoke detector, the present invention uses the ratio of the first infrared light scattering signal to the second blue light scattering signal, combined with the concentration of carbon monoxide, to accurately identify lampblack and water vapor, and is particularly suitable for fire detection in a kitchen scenario. Thus, the present invention provides a detector based on the triple combination of smoke, temperature, and carbon monoxide, which can accurately identify the type of early fire smoke without reducing the sensitivity of the detector.

[0048] A detector based on the triple combination of smoke, temperature, and carbon monoxide can accurately identify the type of early fire smoke without reducing the sensitivity of the detector;

[0049] In a second aspect, the present invention provides a smoke fire detector, including: a controller, a light chamber, and a first light source, a second light source, a third light source, and a photoelectric converter disposed in the light chamber;

[0050] The first light source, the second light source, and the third light source are all LED light sources; the first light source is used to emit a first blue light signal and a first infrared light signal; the second light source is used to emit a second blue light signal; the third light source is used to emit a second infrared light signal; and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter;

[0051] The controller is used to execute the smoke fire detection method provided in the first aspect of the present invention.

[0052] The related technical solutions are the same as the smoke fire detection method provided in the first aspect of the present invention and will not be elaborated here.

[0053] In an optional implementation manner, the above-mentioned smoke fire detector further includes a carbon monoxide sensor for real-time sensing of the concentration N of carbon monoxide in the current environment CO .

[0054] In an optional implementation manner, the above-mentioned smoke fire detector further includes a temperature sensor for real-time sensing of the ambient temperature.

[0055] To further illustrate the smoke fire detection method and detector provided by the present invention, the following will be described in detail with a specific embodiment:

[0056] As Figure 1As shown in the figure, in this embodiment, three LED light sources and a photoelectric converter are arranged in the light chamber of the detector; these three LED light sources are respectively denoted as the first light source, the second light source, and the third light source. The first light source is a dual-wavelength LED light source 1 that can emit two wavelengths of blue light and infrared light. The second light source is an LED light source 3 that can emit blue light. The third light source is an LED light source 2 that can emit infrared light. The photoelectric converter 4 uses a photodiode, which is a photoelectric conversion device that can convert the received light intensity signal into an electrical signal. Denote the blue light signal emitted by the first light source as the first blue light signal, the infrared light signal emitted by the first light source as the first infrared light signal, the blue light signal emitted by the second light source as the second blue light signal, and the infrared light signal emitted by the third light source as the second infrared light signal.

[0057] In this embodiment, the angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both 40°; the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is 140°; the angle between the emission direction of the second infrared signal and the receiving direction of the photoelectric converter is 100°. Specifically, as Figure 2 shown, the spatial angle formed by the dual-wavelength LED light source and the photoelectric converter is 40 degrees, the spatial angle formed by the blue light LED light source and the photoelectric converter is 140 degrees, and the spatial angle formed by the infrared light LED light source and the photoelectric converter is 100 degrees; finally, a temperature sensor and a carbon monoxide sensor are integrated in the fire detector.

[0058] For the convenience of description, in this embodiment, the first blue light signal is denoted as the 40-degree blue light signal, the first infrared light signal is denoted as the 40-degree infrared light signal, the second blue light signal is denoted as the 140-degree blue light signal, and the second infrared light signal is denoted as the 100-degree infrared light signal.

[0059] When smoke enters the fire detector, it will gather in the light chamber maze. Specifically, as shown in 5 of Figure 1 and Figure 2 , the light signal will be scattered when passing through the smoke and finally received by the photoelectric converter.

[0060] This embodiment provides a smoke, temperature, and carbon monoxide triple composite detector and method that can identify black smoke, white smoke, oil fume, dust, and water vapor, including the following steps:

[0061] Step 1, initialize the system. In a smokeless environment, turn on the 40-degree blue light source, the 40-degree infrared light source, the 140-degree blue light source, and the 100-degree infrared light source respectively, and record the AD sampling values of the four-way light scattering signal intensities received by the photodiode respectively, which are the background values of each signal, denoted as

[0062] Step 2: Every time interval t, turn on the 40-degree blue light source, 40-degree infrared light source, 140-degree blue light source, and 100-degree infrared light source respectively, and send four-way optical pulse signals. After subtracting the corresponding background values from the AD sampling values of the four-way light scattering signals received by the photodiode respectively, use the FIR low-pass filter for filtering to remove the high-frequency noise in the signals and obtain the corresponding scattered light intensity change values ΔP B1 , ΔP I1 , ΔP B2 , ΔP I2 ; Among them, considering the computing power of the single-chip microcomputer, the order of the FIR low-pass filter is set to 25, and to filter out high-frequency interference and 50Hz power frequency interference, the cut-off frequency of the filter is set to 30Hz;

[0063] Step 3: When the 40-degree blue light scattering signal ΔP B1 is less than or equal to the preset threshold or when the 40-degree infrared light scattering signal ΔP I1 is less than or equal to the preset threshold or when the 100-degree infrared light scattering signal ΔP I2 is less than or equal to the preset threshold or when the 140-degree blue light scattering signal ΔP B2 is less than or equal to the preset threshold , return to Step 2; when the 40-degree blue light scattering signal ΔP B1 is greater than the preset threshold or when the 40-degree infrared light scattering signal ΔP I1 is greater than the preset threshold or when the 100-degree infrared light scattering signal ΔP I2 is greater than the preset threshold or when the 140-degree blue light scattering signal ΔP B2 is greater than the preset threshold , calculate the slopes K B1 , K I1 , K B2 , K I2 ;

[0064] The intensity of the light scattering signal is the sampling value of the AD converter, which is a discrete digital signal. The slope K of the light scattering signal is obtained by subtracting the light scattering signal measured each time within the previous preset time period from the currently measured light scattering signal and taking the average value, as shown in the following formula:

[0065]

[0066] In the formula, P is the currently measured light scattering signal, P preis the light scattering signal measured at any time during the previous preset time period, and ΔT is the time difference between two measurements of the scattered light signal.

[0067] Step 4, record the concentration of carbon monoxide in the environment, denoted as N CO , record the ambient temperature, denoted as T, and use the slope K of the light scattering signal calculated in the above steps B1 、K I1 、K B2 、K I2 and the preset threshold value K TH to preliminarily judge the type of smoke based on the magnitude relationship between them. Further, use the ratio of the scattered light intensity of the 40-degree infrared light scattering signal to the 140-degree blue light scattering signal and the concentration N of carbon monoxide in the environment CO to distinguish the type of smoke.

[0068] Specifically, the specific method for distinguishing the type of smoke is as follows:

[0069] If the slopes K B1 、K I1 、K B2 、K I2 of the light scattering signal are all greater than the predetermined threshold value K TH , it indicates that the type of smoke may be black smoke or dust. Further, if the ratio R is within the range of [predetermined threshold value R TH1 , predetermined threshold value R TH2 and the concentration N of carbon monoxide CO is higher than the predetermined threshold value N TH1 then the type of smoke is black smoke, and an alarm signal is issued; otherwise, the type of smoke is dust in the typical interference source, and an interference signal is issued;

[0070] If the slopes K B1 、K I1 、K B2 、K I2 of the light scattering signal are all less than or equal to the predetermined threshold value K TH , it indicates that the type of smoke may be white smoke. Further, if the ratio R is within the range of [predetermined threshold value R TH2 , predetermined threshold value R TH3 and the concentration N of carbon monoxide CO is greater than or equal to the predetermined threshold value N TH1 , then the type of smoke is white smoke, and an alarm signal is issued;

[0071] If the slopes K B1 、K I1 are greater than the predetermined threshold value K TH , K B2 、K I2are all less than or equal to a predetermined threshold value K TH , indicating that the type of smoke may be oil fume or water vapor. Further, if the ratio R is within the range of [predetermined threshold value R TH3 , predetermined threshold value R TH4 , and the carbon monoxide concentration N CO is greater than or equal to a predetermined threshold value N TH2 , then the type of smoke is oil fume among the typical interference sources, and an interference signal is emitted; otherwise, the type of smoke is water vapor among the typical interference sources, and an interference signal is emitted;

[0072] Among them, R TH1 <R TH2 <R TH3 <R TH4 ; N TH1 >N TH2 . It should be noted that the slope threshold value K TH , the threshold values R TH1 of the light scattering signal ratio, R TH2 , R TH3 , R TH4 , the carbon monoxide concentration threshold value N TH1 , N TH2 are all determined in advance through known smoke in a laboratory environment. In this embodiment, the values are K TH = 10, R TH1 = 0.5, R TH2 = 0.9, R TH3 = 2.3, R TH4 = 3.3, N TH1 = 60, N TH2 = 30.

[0073] A photodiode is a device that converts a light scattering signal into a current signal. The stronger the light scattering signal, the greater the current output by the photodiode. To reduce high-frequency noise, in this embodiment, an operational amplifier is used to build an integration circuit to convert the current signal output by the photodiode into a voltage signal for the AD converter to collect. The conversion relationship is as follows:

[0074]

[0075] In the formula, U is the voltage signal to be collected; I is the current of the photodiode; C is the capacitance value of the integration capacitor, T is the integration duration, generally dozens of milliseconds; the AD sampling value is the intensity P of the light scattering signal.

[0076] In summary, the present invention uses a four-channel light-emitting diode (LED) light source, with two channels using blue LED light sources and the other two channels using infrared LED light sources (blue light refers to light with a wavelength of 450 nm, and infrared light refers to light with a wavelength of 950 nm). At the same time, a temperature sensor and a carbon monoxide sensor are added on the basis of a point-type photoelectric smoke fire detector to form a point-type smoke, temperature, and carbon monoxide triple composite detector, which can exclude the interference of typical interference sources (oil fume, dust, water vapor) without reducing the sensitivity of the detector, and improve the accuracy of detection of the point-type photoelectric smoke fire detector.

[0077] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A smoke fire detection method, characterized in that Including: Obtain the scattered light intensity value P of the first blue light signal emitted by the current first light source and the scattered light intensity value P of the first infrared light signal respectively through an optoelectronic converter B1 and the scattered light intensity value P of the second blue light signal emitted by the second light source I1 as well as the scattered light intensity value P of the second infrared light signal emitted by the third light source B2 ; subtract them from the corresponding background values and then perform filtering to obtain the corresponding scattered light intensity change values ΔP I2 ΔP B1 ΔP I1 ΔP B2 ΔP I2 ; When ΔP B1 is greater than or ΔP I1 is greater than or ΔP B2 is greater than or ΔP I2 is greater than respectively for the first blue light signal, the first infrared light signal, the second blue light signal and the second infrared light signal, calculate the difference between its current scattered light intensity change value and the scattered light intensity change value at each moment within the previous preset time period, and average all the differences to obtain the slopes K B1 , K I1 , K B2 , K I2 ; When K B1 , K I1 , K B2 , K I2 are all greater than the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH1 , R TH2 , and the current concentration N of carbon monoxide CO is greater than or equal to N TH1 , then it is determined that there is black smoke from a fire and an alarm is issued; When K B1 , K I1 , K B2 , K I2 are all less than or equal to the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH2 , R TH3 , and the current concentration N CO of carbon monoxide is greater than or equal to N TH1 , then it is determined that there is a fire white smoke and an alarm is issued; Among them, K TH , R TH1 , R TH2 , R TH3 , N TH1 are all preset threshold values, and R TH1 < R TH2 < R TH3 ; The first light source, the second light source, and the third light source are all LED light sources, and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter.

2. The smoke fire detection method according to claim 1, characterized in that The angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both within the range of [40°, 90°); the angles between the emission directions of the second blue light signal and the second infrared light signal and the receiving direction of the photoelectric converter are both within the range of (90°, 140°], and the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is greater than the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter.

3. The smoke fire detection method according to claim 1, characterized in that, The angles between the emission directions of the first blue light signal and the first infrared light signal and the receiving direction of the photoelectric converter are both 40°; the angle between the emission direction of the second blue light signal and the receiving direction of the photoelectric converter is 140°; the angle between the emission direction of the second infrared light signal and the receiving direction of the photoelectric converter is 100°.

4. The smoke fire detection method according to any one of claims 1-3, characterized in that, Further including: When K B1 , K I1 , K B2 , K I2 are all greater than the preset threshold value K TH , and the ratio of ΔP I1 to ΔP B2 is not within the range of [R TH1 , R TH2 , and the current concentration N CO of carbon monoxide is less than N TH1 , it is determined to be dust and no alarm is issued; When K B1 and K I1 are both greater than the preset threshold value K TH and, and K B2 and K I2 are both less than or equal to the preset threshold value K TH and, and the ratio of ΔP I1 to ΔP B2 is within the range of [R TH3 , R TH4 and the current concentration N CO of carbon monoxide is greater than or equal to N TH2 , it is determined to be lampblack and no alarm is issued; When K B1 and K I1 are both greater than the preset threshold value K TH and, and K B2 and K I2 are both less than or equal to the preset threshold value K TH and, and the ratio of ΔP I1 to ΔP B2 is not within the range of [R TH3 , R TH4 and the current concentration N of carbon monoxide CO is less than N TH2 , it is determined to be water vapor and no alarm is issued; wherein, R TH4 , N TH2 are both preset threshold values, and R TH4 > R TH3 , N TH2 < N TH1 .

5. A smoke fire detector, characterized in that, Including: A controller, an optical chamber, and a first light source, a second light source, a third light source, and a photoelectric converter arranged in the optical chamber; The first light source, the second light source, and the third light source are all LED light sources; the first light source is used for emitting a first blue light signal and a first infrared light signal; the second light source is used for emitting a second blue light signal; the third light source is used for emitting a second infrared light signal; and the emission directions of the first blue light signal and the first infrared light signal are both acute angles with respect to the receiving direction of the photoelectric converter, and the emission directions of the second blue light signal and the second infrared light signal are both obtuse angles with respect to the receiving direction of the photoelectric converter; The controller is used for executing the smoke fire detection method described in any one of claims 1-4.

6. The smoke fire detector according to claim 5, characterized in that, It also includes a carbon monoxide sensor for real-time sensing of the concentration N of carbon monoxide in the current environment CO .

7. The smoke fire detector according to claim 5 or 6, characterized in that, Further including a temperature sensor for real-time sensing of the ambient temperature.

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