Dual-wavelength smoke temperature composite fire detector and detection method

Abstract

The invention provides a dual-wavelength smoke temperature composite fire detector and a detection method. The dual-wavelength smoke temperature composite fire detector comprises an infrared transmitting device, a blue light transmitting device, a 1 # light receiving device and a 2 # light receiving device, a thermistor is also included; optical axes of the infrared transmitting device, the blue light transmitting device, the 1 # light receiving device and the 2 # light receiving device are intersected at one point, the 1 # light receiving device receives forward scattered light of smoke particles to the infrared transmitting device and backward scattered light of the smoke particles to the blue light transmitting device, and the 2 # light receiving device receives backward scattered light of the smoke particles to the infrared transmitting device; and forward scattering light of the smoke particles to the blue light emitting device; the thermistor obtains environment temperature information; and identifying the type of the smoke according to the forward and backward scattering characteristic data of the smoke under the dual wavelengths and the environment temperature. According to the invention, functions of smoke detection and temperature detection are combined, and accuracy and reliability of fire detection are greatly improved by monitoring fire characteristic parameters of smoke and temperature at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of fire detection and alarm, and in particular to a dual-wavelength smoke-temperature composite fire detector and a detection method. Background Art

[0002] In the field of fire safety, fire detectors are one of the key components. Photoelectric smoke detectors based on the scattering principle and temperature detectors based on thermistors are the two most widely used fire detectors. Photoelectric smoke detectors use the smoke generated in the early stage of a fire to change the transmission characteristics of light to detect fire. When smoke enters the detector, it changes the optical path between the light emitting tube and the light receiving tube, causing the received light intensity to change, and then generates an electrical signal change. The detector issues an alarm based on the electrical signal state. Temperature detectors use temperature-sensitive thermistors to detect changes in external temperature. When a fire occurs, the ambient temperature rises rapidly, and the physical properties of the thermistor (such as resistance) change. The detector converts this change into temperature change. The smoke-temperature composite detector, also known as a composite smoke-temperature fire detector or a smoke-temperature integrated detector, is a device that combines the functions of a smoke detector and a temperature detector in the same detector. It can detect smoke and temperature at the same time, which can improve the accuracy and timeliness of fire detection. In addition, composite detection technology can be used in the alarm algorithm to reduce false alarms and missed alarms.

[0003] Due to differences in particle size, composition, microscopic morphology and other factors, different types of smoke particles have significantly different scattering intensities for the same wavelength of light at different angles, and also have significantly different scattering intensities for different wavelengths of light at the same angle.

[0004] Existing smoke and temperature composite detectors use a single wavelength and angle scattering signal to detect smoke concentration when detecting smoke. Since non-fire smoke particles (such as water mist and dust) also scatter light, it can cause false alarms. In addition, some fire smoke particles do not scatter light significantly, making it difficult to trigger the alarm, resulting in missed reports of fire smoke. Therefore, it is necessary to improve the anti-interference ability of smoke and temperature composite detectors to solve the problem of inconsistent detection performance for different types of smoke. Summary of the invention

[0005] In view of the defects in the prior art, an object of the present invention is to provide a dual-wavelength smoke and temperature composite fire detector and a detection method.

[0006] A dual-wavelength smoke and temperature composite fire detector provided by the present invention comprises: an infrared emitting device, a blue light emitting device, a 1# light receiving device, a 2# light receiving device; and a thermistor;

[0007] The optical axes of the infrared emitting device, the blue light emitting device, the 1# light receiving device, and the 2# light receiving device intersect at one point, the 1# light receiving device receives the forward scattered light of the infrared emitting device from smoke particles, and the backscattered light of the blue light emitting device from smoke particles, and the 2# light receiving device receives the backscattered light of the infrared emitting device from smoke particles, and the forward scattered light of the blue light emitting device from smoke particles;

[0008] The thermistor obtains ambient temperature information;

[0009] The type of smoke can be identified based on the forward and backward scattering characteristic data of the smoke at dual wavelengths and the ambient temperature.

[0010] Preferably, it further comprises: a smoke chamber cover and a smoke chamber, wherein the smoke chamber cover and the smoke chamber surround and form a smoke detection chamber;

[0011] The periphery of the smoke chamber is provided with a circle of light shielding sheets which are embedded end to end. The light shielding sheets include a pointed head and an open tail. The head of each light shielding sheet is embedded in the tail of the adjacent light shielding sheet.

[0012] The smoke chamber is provided with a cylinder, and the smoke chamber cover is provided with a mounting hole which is interference-fitted with the cylinder;

[0013] The infrared emitting device, the blue light emitting device, the 1# light receiving device and the 2# light receiving device are located in a light shielding space surrounded by the guide sheet and the smoke chamber cover.

[0014] Preferably, it also includes a metal insect-proof net, which is arranged around the periphery of the shading sheet.

[0015] Preferably, the infrared emitting device and the blue light emitting device are located in the same plane, and the center line angle is 145°, and the 1# light receiving device and the 2# light receiving device are placed symmetrically about the emitting device, and the center line angle is 90°.

[0016] Preferably, it also includes a top cover and a main shell;

[0017] The top cover is installed on the main shell, and the main shell is arranged on the top of the smoke detection chamber. The outer surface of the main shell is provided with guide sheets distributed in a ring shape, and the inner side of the guide sheets is provided with openings. The air enters the interior of the detector from the openings through the guide sheets and enters the interior of the smoke detection chamber.

[0018] Preferably, it also includes a circuit board;

[0019] The infrared emitting device, the blue light emitting device, the 1# light receiving device, the 2# light receiving device and the thermistor are all electrically connected to the circuit board;

[0020] The circuit board is provided with a light emitting and receiving device bracket, and the light emitting and receiving device bracket is provided with a fixing groove, and the infrared emitting device, the blue light emitting device, the 1# light receiving device and the 2# light receiving device are fixed through the fixing groove;

[0021] The optical emitting and receiving device support comprises a thin tube, and the thermistor is extended and arranged in the thin tube.

[0022] Preferably, an alarm light is provided on the circuit board;

[0023] It also includes a light guide, which is made of transparent material. The light guide includes a light guide column, and one end of the light guide column is arranged close to the alarm light.

[0024] Preferably, a light shielding structure is provided on the bottom surface of the optical emitting and receiving device bracket close to the circuit board, and the light shielding structure is located at the installation position of the 1# optical receiving device and the 2# optical receiving device.

[0025] Preferably, a plurality of vertical smooth sheets are provided on the smoke chamber cover, and the smooth sheets are arranged parallel to the light emitting device.

[0026] A detection method of a dual-wavelength smoke-temperature composite fire detector provided by the present invention comprises: obtaining forward and backward scattered light signals of smoke at two wavelengths through two light emitting devices and two light receiving devices, and obtaining the ambient temperature through a thermistor;

[0027] A fire detection alarm model is established, and the forward and backward scattered light signals of two wavelengths and temperature information of smoke are used as the input of the model. A neural network model is used to identify and classify the smoke type. After the smoke type is identified, an alarm is issued according to the threshold corresponding to the smoke type.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention combines the functions of smoke detection and temperature detection, and greatly improves the accuracy and reliability of fire detection by simultaneously monitoring the fire characteristic parameters of smoke and temperature. This composite detection method enables the detector to detect and alarm in time at the early stage of a fire, effectively preventing the spread of fire.

[0030] 2. The present invention uses two light emitting devices and two light receiving devices with a specially designed smoke detection chamber to detect the forward and backward scattering characteristic data of smoke at dual wavelengths. The recognition algorithm distinguishes common interferences such as dust and water mist, so that the detector can greatly reduce false alarms.

[0031] 3. The smoke detection chamber disclosed in the present invention can almost completely avoid the influence of ambient light changes on smoke detection, reduce the reference value deviation caused by dust accumulation, and improve the accuracy and stability of the detector.

[0032] 4. The metal insect-proof net 5 configured in the smoke detection chamber disclosed in the present invention can prevent insects and large floating particles from accidentally entering, can reduce the entry of water vapor into the smoke detection chamber, and can reduce false alarms. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0034] Figure 1 It is a schematic diagram of the structure of the dual-wavelength smoke and temperature composite fire detector in the present invention;

[0035] Figure 2 It is a schematic diagram of the top cover structure in the present invention;

[0036] Figure 3 It is a schematic diagram of the main housing structure in the present invention;

[0037] Figure 4 This is a schematic diagram of the smoke chamber cover structure of the present invention;

[0038] Figure 5 This is a schematic diagram of the smoke chamber structure of the present invention;

[0039] Figure 6 It is a schematic diagram of the smoke chamber structure from another angle in the present invention;

[0040] Figure 7 It is a schematic diagram of the structure of the optical emitting and receiving device bracket in the present invention.

[0041] Description of reference numerals:

[0042] DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0044] The dual-wavelength smoke and temperature composite fire detector of the present invention uses an infrared emitting device 9 and a blue light emitting device 10 to irradiate the smoke in smoke detection, uses a 1# light receiving device 11 and a 2# light receiving device 12 to receive the scattered light of the smoke in the front and rear directions, and obtains the forward and backward scattered light signals of the smoke at two wavelengths; the temperature detection uses a thermistor 8 as a sensitive element, and detects the temperature by measuring the voltage across a fixed resistor connected in series with the thermistor 8.

[0045] By establishing a fire detection alarm model, using the forward and backward scattering information of smoke at two wavelengths and temperature information as the input of the model, an interference recognition algorithm is added to the fire detection alarm model to reduce false alarms, and a smoke type recognition algorithm is added to improve the consistency of different types of smoke alarms. The control unit integrated on the specially designed circuit board 13 can control the operation of the light emitting and light receiving devices, and process the collected information at the same time. Through the innovative smoke chamber 6 and product structure design, the smoke and temperature composite detector can reduce the interference of the environment and work more stably and reliably.

[0046] like Figures 1 to 7 As shown, a dual-wavelength smoke temperature composite detector of the present invention structurally includes a top cover 1, a light guide 2, a main shell 3, a smoke chamber cover 4, a metal insect-proof net 5, a smoke chamber 6, a light emitting and receiving device bracket 7, a thermistor 8, an infrared emitting device 9, a blue light emitting device 10, a 1# light receiving device 11, a 2# light receiving device 12, a circuit board 13 and a bottom shell 14.

[0047] The top cover 1 is connected and positioned with the main housing 3 through the hook 16, and the light guide 2 is installed between the top cover 1 and the main housing 3, and is limited by the hole and groove on the main housing 3. The smoke chamber cover 4 is connected with the cylinder 64 on the smoke chamber 6 by interference fit, and the smoke chamber cover 4 and the smoke chamber 6 together constitute a smoke detection chamber after being connected, and the mounting lug 63 on the smoke chamber 6 is fixed to the bottom shell 14 by screws. The metal insect-proof net 5 is fixed on the smoke chamber 6. The optical emitting and receiving device bracket 7 is provided with a fixing groove 72, and the infrared emitting device 9, the blue light emitting device 10, the 1# optical receiving device 11, and the 2# optical receiving device 12 are fixed by the groove on the optical emitting and receiving device bracket 7; the infrared emitting device 9, the blue light emitting device 10, the 1# optical receiving device 11, the 2# optical receiving device 12 and the thermistor 8 are connected to the circuit board 13; the optical emitting and receiving device bracket 7 is connected to the circuit board 13 through a buckle 73; the circuit board 13 is connected to the bottom shell 14 through screws, and the bottom shell 14 is connected and fixed to the main shell 3 through screws.

[0048] The optical axes of the infrared emitting device 9, the blue light emitting device 10, the 1# light receiving device 11, and the 2# light receiving device 12 on the dual-wavelength smoke temperature composite detector intersect at one point. The 1# light receiving device 11 receives the forward scattered light of the smoke particles on the infrared emitting device 9 and the backscattered light of the blue light emitting device 10, and the 2# light receiving device 12 receives the backscattered light of the smoke particles on the infrared emitting device 9 and the forward scattered light of the blue light emitting device 10.

[0049] Reference Figure 1 , Figure 6 as well as Figure 7 As shown, the infrared emitting device 9, the blue light emitting device 10, the 1# light receiving device 11, and the 2# light receiving device 12 are all installed in the fixing groove 72 on the light emitting and receiving device bracket 7. When the installation is completed, the light emitting device and the receiving device enter the light guide groove 61 from the opening at the end of the light guide groove 61, so as to measure the smoke in the smoke chamber 6. The light emitting angle and the light receiving angle are fixed by the fixing groove 72 and the light guide groove 61. Figure 5 As shown, a shading structure 65 is provided at the bottom of the smoke chamber 6 at one end of the 1# light receiving device 11 and the 2# light receiving device 12. The shading structure 65 is used to prevent the light emitted by the light emitting device from entering the light receiving device through gaps or scattering effects, causing problems such as poor consistency and excessive background signals.

[0050] The entire smoke detection chamber can be divided into three parts: upper, middle and lower. The upper part is designed with a circumferentially distributed "human" shaped light shielding sheet 62, which includes a pointed head and an open tail. The head of each light shielding sheet 62 is embedded in the tail of the adjacent light shielding sheet 62 to form a head-to-tail embedding, which plays a role in allowing airflow to enter the smoke detection chamber and making it difficult for ambient light to enter the smoke detection chamber; the middle part is the fixed structure of the light emitting device and the light receiving device and the light shielding structure 65, and the lower part is the smoke chamber 6 fixed structure and the circuit board 13 protective cover. The smoke chamber cover 4 is provided with a plurality of vertical smooth sheets 41, and the direction of the smooth sheets 41 is parallel to the light emitting device. The metal insect-proof net 5 uses an etching process to process dense honeycomb-shaped regular hexagonal holes on the stainless steel sheet.

[0051] The smoke detection chamber has the function of blocking the entry of external light. At the same time, the design of the smoke detection chamber can allow the airflow containing smoke to enter and exit smoothly. The structural design of the smoke detection chamber can also prevent the light emitted by the light emitting device from entering the light receiving device through the gap or scattering effect, causing poor consistency and excessive background signal. In addition, the structural design of the smoke detection chamber can avoid drift caused by dust accumulation.

[0052] In a preferred embodiment, the infrared emitting device 9 is a plug-in lamp bead with a peak wavelength of 850nm, the blue light emitting device 10 is a plug-in lamp bead with a peak wavelength of 470nm, and the light receiving device is a plug-in photodiode with a sensing wavelength of 400-1100nm.

[0053] Reference Figure 7 As shown, the two light emitting devices are in the same plane, and the center line angle is about 145°. The center lines of the two light receiving devices intersect with the center lines of the two light emitting devices at the same point. The two light receiving devices are placed symmetrically, and the center line angle is about 90°. The forward scattering angle of smoke for the two wavelengths is about 45°, and the backward scattering angle is about 135°.

[0054] The metal insect screen 5 made of stainless steel sheet etching has the characteristics of small aperture and large hollow ratio. The smaller aperture has better protection effect on small mosquitoes and insects, and also has better filtering effect on large dust particles or floating objects. The large hollow ratio can reduce the obstruction of smoke, which is conducive to the entry of smoke into the smoke detection room. In addition, the metal insect screen 5 has the advantage of good effect on water vapor condensation, which can reduce the entry of water vapor into the smoke detector.

[0055] The thermistor 8 is located on the central axis of the dual-wavelength smoke temperature composite detector and extends to the middle of the top cover 1 through the thin tube 71 on the light emitting and receiving device bracket 7. In a preferred embodiment, the thermistor 8 is an NTC thermistor 8 with a resistance of 100KΩ at 25°C.

[0056] The top cover 1 has a large-area hollow air inlet 15, which allows airflow to pass smoothly in different directions, which is beneficial for the thermistor 8 to detect the temperature of the environment.

[0057] The main shell 3 has a plurality of guide fins 31 and openings 32 in the radial direction. The design of the guide fins 31 and the openings 32 is simulated and optimized, which is conducive to the airflow entering the smoke detection chamber smoothly and quickly at different directions.

[0058] The light guide 2 is made of transparent plastic material and has two parallel light guide column structures and a circular ring structure perpendicular thereto. The light emitted by the alarm light on the circuit board 13 is coupled into the light guide column structure of the light guide 2 and then totally reflected and directed into the circular ring structure. The circular ring structure has a raised texture that can reflect the light more evenly, so that people can observe light signals in different directions to indicate the fire alarm or other status of the dual-wavelength smoke and temperature composite fire detector.

[0059] In the dual-wavelength smoke-temperature composite detector disclosed in the present invention, forward and backward scattered light signals of smoke at two wavelengths are obtained through two light emitting devices and two light receiving devices; temperature detection uses a thermistor 8 as a temperature detection element, and detects temperature by measuring the voltage across a fixed resistor connected in series with the thermistor 8. The control unit on the circuit board 13 performs electrical control and signal acquisition on the light emitting device, the light receiving device and the thermistor. By utilizing the difference in the forward and backward scattered signal characteristics of smoke to two wavelengths of light, common interference types including but not limited to dust and water vapor can be identified, and smoke-temperature composite information is used to further eliminate interference and effectively avoid false alarms.

[0060] In a specific embodiment, the detector disclosed in the present invention automatically adjusts the alarm threshold for different smoke types, utilizes the difference in the forward and backward scattering signal characteristics of smoke to two wavelengths of light to identify the type of smoke, and automatically adjusts the alarm threshold for the type of smoke to ensure the consistency of the alarm sensitivity of different types of smoke detection. Specifically: a neural network model is used to identify and classify the smoke type, and after the smoke type is identified, an alarm is issued according to the threshold corresponding to the smoke type, and the alarm thresholds of different types of smoke are calibrated using an optical smoke density meter.

[0061] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0062] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A dual-wavelength smoke and temperature composite fire detector, characterized in that: include: Infrared emitting device (9), blue light emitting device (10), 1# light receiving device (11), 2# light receiving device (12); also includes a thermistor (8); The optical axes of the infrared emitting device (9), the blue light emitting device (10), the first light receiving device (11), and the second light receiving device (12) intersect at one point; the first light receiving device (11) receives forward scattered light from smoke particles to the infrared emitting device (9) and back scattered light from smoke particles to the blue light emitting device (10); and the second light receiving device (12) receives back scattered light from smoke particles to the infrared emitting device (9) and forward scattered light from smoke particles to the blue light emitting device (10); The thermistor (8) obtains ambient temperature information; The type of smoke can be identified based on the forward and backward scattering characteristic data of the smoke at dual wavelengths and the ambient temperature.

2. The dual-wavelength smoke and temperature composite fire detector according to claim 1 is characterized in that: Also includes: A smoke chamber cover (4) and a smoke chamber (6), wherein the smoke chamber cover (4) and the smoke chamber (6) surround and form a smoke detection chamber; A circle of light shielding sheets (62) embedded end to end is arranged on the periphery of the smoke chamber (6), the light shielding sheets (62) comprising a pointed head and an open tail, the head of each light shielding sheet (62) being embedded in the tail of an adjacent light shielding sheet (62); The smoke chamber (6) is provided with a cylinder, and the smoke chamber cover (4) is provided with a mounting hole which is interference-fitted with the cylinder; The infrared emitting device (9), the blue light emitting device (10), the 1# light receiving device (11) and the 2# light receiving device (12) are located in a light shielding space surrounded by the guide sheet (31) and the smoke chamber cover (4).

3. The dual-wavelength smoke and temperature composite fire detector according to claim 2 is characterized in that: It also comprises a metal insect-proof net (5), wherein the metal insect-proof net (5) is arranged around the periphery of the light-shielding sheet (62).

4. The dual-wavelength smoke and temperature composite fire detector according to claim 1 is characterized in that: The infrared emitting device (9) and the blue light emitting device (10) are located in the same plane, and the center line angle is 145°; the 1# light receiving device (11) and the 2# light receiving device (12) are placed symmetrically with respect to the emitting device, and the center line angle is 90°.

5. The dual-wavelength smoke and temperature composite fire detector according to claim 2 is characterized in that: It also includes a top cover (1) and a main housing (3); The top cover (1) is mounted on the main shell (3), and the main shell (3) is arranged on the top of the smoke detection chamber. The outer surface of the main shell (3) is provided with guide sheets (31) distributed along a ring shape, and the inner side of the guide sheets (31) is provided with openings (32). Air passes through the guide sheets (31) and enters the interior of the detector from the openings (32), and then enters the interior of the smoke detection chamber.

6. The dual-wavelength smoke and temperature composite fire detector according to claim 1 is characterized in that: Also includes a circuit board (13); The infrared emitting device (9), the blue light emitting device (10), the 1# light receiving device (11), the 2# light receiving device (12) and the thermistor (8) are all electrically connected to the circuit board (13); The circuit board (13) is provided with a light emitting and receiving device bracket (7), the light emitting and receiving device bracket (7) is provided with a fixing groove (72), and the infrared emitting device (9), the blue light emitting device (10), the first light receiving device (11) and the second light receiving device (12) are fixed through the fixing groove (72); The optical emitting and receiving device support (7) comprises a thin tube (71), and the thermistor (8) is extended and arranged in the thin tube (71).

7. The dual-wavelength smoke and temperature composite fire detector according to claim 6 is characterized in that: The circuit board (13) is provided with an alarm light; It also comprises a light guide (2), the light guide (2) is made of a transparent material, the light guide (2) comprises a light guide column, one end of the light guide column is arranged close to the alarm light.

8. The dual-wavelength smoke and temperature composite fire detector according to claim 6 is characterized in that: A light shielding structure (65) is provided on the bottom surface of the optical emitting and receiving device bracket (7) close to the circuit board (13), and the light shielding structure (65) is located at the installation position of the 1# optical receiving device (11) and the 2# optical receiving device (12).

9. The dual-wavelength smoke and temperature composite fire detector according to claim 2, characterized in that: A plurality of vertical smooth thin sheets (41) are arranged on the smoke chamber cover (4), and the smooth thin sheets (41) are arranged parallel to the light emitting device.

10. A detection method of a dual-wavelength smoke and temperature composite fire detector, based on the dual-wavelength smoke and temperature composite fire detector according to any one of claims 1 to 9, characterized in that: include: Through two light emitting devices and two light receiving devices, forward and backward scattered light signals of smoke at two wavelengths are obtained, and the ambient temperature is obtained through a thermistor (8); a fire detection alarm model is established, and the forward and backward scattered light signals of smoke at two wavelengths and temperature information are used as inputs of the model, and a neural network model is used to identify and classify the smoke type. After the smoke type is identified, an alarm is issued according to a threshold value corresponding to the smoke type.

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