Flame detector based on high curie point relaxor ferroelectric single crystal

Abstract

The invention relates to a flame detector based on a high curie point relaxor ferroelectric single crystal. The flame detector comprises a shell, a bottom plate, a shell cover, a PCB group, a main control module and an infrared sensor, the bottom plate and the shell cover are installed at the two ends of the shell respectively, the PCB set is arranged in the shell and is of a multi-layer structure, the main control module and the infrared sensor are connected with each other and are fixed to the PCB set respectively, and the optical lens is installed on the shell cover; the infrared sensor is a relaxor ferroelectric single crystal pyroelectric sensor, the chemical composition of the relaxor ferroelectric single crystal of the infrared sensor is (1-x-y) Pb (In1 / 2Nb1 / 2) O < 3-y > Pb (Mg1 / 3Nb2 / 3) O < 3-x > bTiO < 3-z > Mn, x is equal to 0.20-0.40, y is equal to 0.18-0.60, and z is equal to 0.003-0.03. Compared with the prior art, the system has the advantages of high anti-interference capability, long detection distance and the like.

Description

Technical Field

[0001] The invention relates to the technical field of flame detection, in particular to a flame detector based on a high Curie point relaxor ferroelectric single crystal. Background Art

[0002] Flame detectors play an important role in fire fighting. Since the flames in the early stages of a fire contain ultraviolet and infrared rays of different wavelengths that are invisible to the naked eye, flame detectors can be used to detect fires in a timely manner, effectively preventing the spread of fire and reducing losses caused by fire.

[0003] Flame detectors are also called photosensitive fire detectors. They are used to respond to the optical characteristics of fire. When a substance burns, it produces smoke and heat, and also produces visible or invisible light radiation that is not in the atmosphere. The flame detector will detect it. Among them, the infrared flame detector that relies on detecting infrared light to realize the alarm function is called an infrared flame detector. Infrared spectrum flame detection technology mainly uses the "atmospheric window principle" on the earth's surface. Sunlight is a full light spectrum. When penetrating the earth's atmosphere, due to the nitrogen in the atmosphere, 2 , O 2 , O 3 , H 2 O、CO 2 Gases absorb part of the spectrum, and there is almost no energy near the center of the infrared band of 4.0-5.0μm that reaches the earth's surface. However, ordinary organic matter or gas combustion has high energy characteristics in this band, so it is effective to judge flame combustion by monitoring the flame characteristic band of the infrared "atmospheric window".

[0004] At present, there are many flame detector products for fire protection on the market, but due to the limitation of technology level and environmental influences such as temperature and humidity, they are prone to failure or false alarm. Most flame detectors use pyroelectric sensors with lithium tantalate as sensitive elements for data acquisition. The sensitivity and accuracy of sensor data acquisition will directly affect the range and response time of flame detection, and its signal-to-noise ratio will also affect the false alarm of flame detection. These problems may lead to false alarms, missed alarms and performance degradation, requiring regular maintenance and calibration, affecting its reliability and stability in complex environments.

[0005] For example, the invention with publication number CN103943771A discloses a relaxor ferroelectric single crystal pyroelectric infrared detector and a method for preparing the same. The detector comprises: a base provided with pins; a shell with a window packaged together with the base to form a receiving space; a sensitive element arranged in the receiving space, the sensitive element being made of a relaxor ferroelectric single crystal and having a thickness of less than 20 μm; an upper electrode and a lower electrode respectively arranged on the upper surface of the sensitive element and the lower surface of the sensitive element; an absorption layer covering the upper electrode of the sensitive element; and a current mode circuit connected to the sensitive element.

[0006] The above-mentioned prior art pyroelectric infrared sensor based on relaxor ferroelectric single crystal has a high voltage response rate and specific detection rate, but the Curie temperature of the relaxor ferroelectric single crystal needs to be further improved to adapt to more harsh environments and further improve the detection level and anti-interference ability of the sensor. Summary of the invention

[0007] The purpose of the present invention is to provide a flame detector based on a high Curie point relaxor ferroelectric single crystal in order to overcome the defects of the above-mentioned prior art that the sensor based on the relaxor ferroelectric single crystal has a low Curie temperature, which limits the detection level and anti-interference ability of the sensor.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A flame detector based on a high Curie point relaxor ferroelectric single crystal, comprising a housing, a bottom plate, a housing cover, a PCB board assembly, a main control module and an infrared sensor;

[0010] The bottom plate and the shell cover are respectively installed at two ends of the shell, the PCB board group is arranged inside the shell and has a multi-layer structure, the main control module and the infrared sensor are connected to each other and are respectively fixed on the PCB board group, and the shell cover is installed with an optical lens;

[0011] The infrared sensor is a relaxor ferroelectric single crystal pyroelectric sensor, and the chemical composition of the relaxor ferroelectric single crystal of the infrared sensor is: (1-xy)Pb(In 1 / 2 Nb 1 / 2 ) 3 -yPb(Mg 1 / 3 Nb 2 / 3 ) 3 -xbTiO 3 -zMn, wherein x=0.20-0.40, y=0.18-0.60, z=0.003-0.03.

[0012] Preferably, an infrared light emitting tube is provided at one end of the PCB board group close to the shell cover, the infrared light emitting tube is connected to the main control module, the infrared sensor is arranged adjacent to the infrared light emitting tube, and the infrared light emitting tube is used to transmit an infrared signal to the infrared sensor.

[0013] Preferably, a columnar tube for mounting an infrared light-emitting tube is provided on the PCB board group, and a reflective cap and a light-transmitting hole are provided at one end of the columnar tube away from the PCB board group. The infrared signal emitted by the infrared light-emitting tube is reflected to the receiving end of the infrared sensor through the reflective cap; the light-transmitting hole is located between the reflective cap and the emitting end of the infrared light-emitting tube.

[0014] Preferably, the infrared light emitting tube is installed at the center of the PCB board group close to one end of the shell cover, and there are multiple infrared sensors, each of which is evenly distributed around the infrared light emitting tube.

[0015] Preferably, the infrared sensor is a pyroelectric external sensor with a filter, and the filter on each infrared sensor has a different light transmission band, and the light transmission band ranges from 2.7 to 5.1 μm.

[0016] Preferably, a signal light is further provided at one end of the PCB board group close to the shell cover, and the signal light is connected to the main control module. Different flashing colors of the signal lights are used to display the working status of the flame detector.

[0017] Preferably, the PCB board assembly comprises a mounting plate, a first fixing plate and a second fixing plate;

[0018] The infrared sensor is fixed on a mounting plate, a metal bracket is provided between the first fixing plate and the second fixing plate, the first fixing plate and the second fixing plate are spaced and connected by the metal bracket, the mounting plate is fixed by bolts on a side of the first fixing plate away from the second fixing plate, and the main control module is installed on a side of the second fixing plate close to the first fixing plate.

[0019] Preferably, the shell cover is threadedly connected to the shell, a U-shaped groove is provided at the connection between the shell and the housing, a circular rubber pad is provided in the U-shaped groove, and an anti-radio frequency coating, a rubber inner membrane and a heat insulation layer are provided on the inner wall of the shell.

[0020] Preferably, the main control module is integrated with a main control circuit, a power supply circuit, an alarm circuit, a communication circuit, and a control circuit for a signal lamp and an infrared light emitting tube.

[0021] Preferably, the orientation of the relaxor ferroelectric single crystal is <100> Direction or <111> direction, the operating temperature range of the flame detector is -100-110°C, and the operating frequency range of the flame detector is 0.1-39.8Hz.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) This solution uses a new type of relaxor ferroelectric single crystal pyroelectric sensor, and integrates the infrared sensor and the main control module on a PCB board group inside the shell. When a fire occurs in the detection environment, the infrared light generated by the flame can enter the shell through the optical lens on the shell cover, and then be detected by the infrared sensor and transmitted to the main control module for processing.

[0024] By using an infrared sensor made of a new relaxor ferroelectric single crystal for flame detection, based on the high Curie point characteristics of the new relaxor ferroelectric single crystal, the infrared sensor has better voltage response capability and lower signal-to-noise ratio. Compared with the traditional pyroelectric infrared sensor made of relaxor ferroelectric single crystal, the detection level and anti-interference ability of the infrared sensor using the new relaxor ferroelectric single crystal are further improved.

[0025] (2) This solution sets an infrared light-emitting tube controlled by the main control module near the infrared sensor. The infrared light-emitting tube can directly transmit infrared signals to the infrared sensor. If the infrared sensor is not faulty, it can receive infrared signals normally and the flame detector alarms. If the flame detector does not work, it means that the infrared sensor is faulty. The infrared light-emitting tube can be used to regularly self-check the infrared sensor to ensure that the flame detector can work normally, reducing the workload of on-site maintenance, improving maintenance efficiency, and improving the reliability of the flame detector.

[0026] (3) This scheme installs the infrared light-emitting tube in the columnar tube. The infrared signal emitted by the infrared light-emitting tube is transmitted to the reflective cap through the light-transmitting hole, and then reflected to the receiving end of the infrared sensor through the reflective cap, completing the self-detection of the infrared sensor. The light-transmitting hole and the reflective plate are set in such a way that the infrared sensor receives the signal from the infrared light-emitting tube as much as possible, thereby improving the accuracy of the infrared sensor's self-detection. In addition, multiple infrared sensors are set around the infrared light-emitting tube and are equipped with filters, thereby narrowing the detection range of the infrared sensor and improving the detection accuracy and anti-interference ability of the flame detector.

[0027] (4) In this solution, the main control module can process the detection signal of the infrared sensor, transmit the detection environment conditions to the signal light, and flash the signal light of the corresponding color according to the detection result to show the current environmental problems to the outside world, making the detection result more intuitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the explosion structure of the flame detector provided by the present invention;

[0029] Figure 2 A schematic diagram of the structure of the components on the PCB board assembly provided by the present invention;

[0030] Figure 3 A schematic top view of the upper end surface of the PCB board assembly provided by the present invention;

[0031] Figure 4 A schematic diagram of the structure of the infrared sensor and the infrared light emitting tube provided by the present invention;

[0032] Figure 5 The simulation data and experimental data diagram of voltage response rate and frequency change provided by the present invention;

[0033] Figure 6 This is a diagram of the experimental results of the anti-interference of the flame detector provided by the present invention;

[0034] Figure 7 A schematic diagram of the flame detector provided by the present invention for detecting various burning objects;

[0035] In the figure: 1. outer shell, 2. bottom plate, 3. shell cover, 4. PCB board assembly, 31. optical lens, 41. infrared light emitting tube, 42. reflective cap, 43. mounting plate, 44. first fixing plate, 45. second fixing plate, 46. infrared sensor, 47. filter, 48. signal light. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0039] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0040] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] Example 1

[0043] like Figure 1 and Figure 2 As shown, this embodiment provides a flame detector based on a high Curie point relaxor ferroelectric single crystal, comprising a housing 1, a bottom plate 2, a housing cover 3, a PCB board group 4, a main control module and an infrared sensor;

[0044] The bottom plate 2 and the shell cover 3 are respectively installed at both ends of the shell 1, the PCB board group 4 is arranged inside the shell 1 and has a multi-layer structure, the main control module and the infrared sensor are connected to each other and fixed on the PCB board group 4 respectively, and the shell cover 3 is installed with an optical lens 31;

[0045] The infrared sensor is a relaxor ferroelectric single crystal pyroelectric sensor. The chemical composition of the relaxor ferroelectric single crystal of the infrared sensor is: (1-xy)Pb(In 1 / 2 Nb 1 / 2 ) 3 -yPb(Mg 1 / 3 Nb 2 / 3 ) 3 -xbTiO 3 -zMn, where x = 0.20-0.40, y = 0.18-0.60, z = 0.003-0.03, and the orientation of the single crystal is <100> Direction or <111> The Curie temperature of the relaxor ferroelectric single crystal is in the range of 180-250°C.

[0046] A new type of relaxor ferroelectric single crystal pyroelectric sensor is used, and the infrared sensor and the main control module are integrated on a PCB board group in the housing 1. When a fire occurs in the detection environment, the infrared light generated by the flame can enter the housing 1 through the optical lens 31 on the shell cover 3, and then be detected by the infrared sensor and transmitted to the main control module for processing.

[0047] By using an infrared sensor made of a new relaxor ferroelectric single crystal for flame detection, based on the high Curie point characteristics of the new relaxor ferroelectric single crystal, the infrared sensor has better voltage response capability and lower signal-to-noise ratio. Compared with the traditional pyroelectric infrared sensor made of relaxor ferroelectric single crystal, the detection level and anti-interference ability of the infrared sensor using the new relaxor ferroelectric single crystal are further improved.

[0048] In a preferred embodiment, an infrared light emitting tube 41 is provided at one end of the PCB board group 4 close to the shell cover 3, the infrared light emitting tube 41 is connected to the main control module, and an infrared sensor 46 is arranged adjacent to the infrared light emitting tube 41, and the infrared light emitting tube 41 is used to emit infrared signals to the infrared sensor 46.

[0049] An infrared light emitting tube 41 controlled by the main control module is arranged near the infrared sensor 46. The infrared light emitting tube 41 can directly transmit an infrared signal to the infrared sensor 46. If the infrared sensor 46 is not faulty, it can normally receive the infrared signal and the flame detector alarms; if the flame detector does not work, it means that the infrared sensor 46 is faulty. The infrared light emitting tube 41 can periodically perform self-inspection on the infrared sensor 46 to ensure that the flame detector can work normally, reduce the workload of on-site maintenance, improve maintenance efficiency, and improve the reliability of the flame detector.

[0050] The self-inspection is carried out by direct radiation of the infrared light source in the window, and the infrared light source that can replace the open flame is introduced. The automated self-inspection system reduces manual intervention, makes the operation easier during inspection, and improves the safety and reliability of the fire detector.

[0051] Specifically, if Figure 2 and Figure 3 As shown, a columnar tube for mounting an infrared light-emitting tube 41 is provided on the PCB board group 4, and a reflective cap 42 and a light-transmitting hole are provided at one end of the columnar tube away from the PCB board group 4. The infrared signal emitted by the infrared light-emitting tube 41 is reflected by the reflective cap 42 to the receiving end of the infrared sensor 46; the light-transmitting hole is located between the reflective cap 42 and the emitting end of the infrared light-emitting tube 41.

[0052] The infrared light emitting tube 41 is installed at the center of the PCB board assembly 4 close to one end of the shell cover 3 . There are multiple infrared sensors 46 , and each infrared sensor 46 is evenly distributed around the infrared light emitting tube 41 .

[0053] The infrared sensor 46 is a pyroelectric external sensor with a filter 47. The filter 47 on each infrared sensor 46 has a different light transmission band, and the light transmission band ranges from 2.7 to 5.1 μm. In this embodiment, there are four pyroelectric external sensors with filters 47, and the filters 47 on each sensor allow light to pass through the bands of 2.7 μm, 3.8 μm, 4.3 μm, and 5.1 μm, respectively.

[0054] The infrared light-emitting tube is installed in the columnar tube, and the infrared signal emitted by the infrared light-emitting tube is emitted to the reflective cap through the light-transmitting hole, and is reflected to the receiving end of the infrared sensor 46 through the reflective cap, thereby completing the self-detection of the infrared sensor 46. The light-transmitting hole and the reflective plate are arranged so that the infrared sensor 46 can receive the signal from the infrared light-emitting tube as much as possible, thereby improving the accuracy of the self-detection of the infrared sensor 46. In addition, multiple infrared sensors 46 are arranged around the infrared light-emitting tube, and are provided with a filter 47, thereby narrowing the detection range of the infrared sensor 46 and improving the detection accuracy and anti-interference ability of the flame detector. Among them, the columnar tube for installing the infrared light-emitting tube can be made of rigid materials, including plastics and metals, which are not limited here.

[0055] In a preferred embodiment, a signal light 48 is further provided at one end of the PCB assembly 4 close to the housing cover 3. The signal light 48 is connected to the main control module, and the flashing colors of each signal light 48 are different to indicate the working state of the flame detector. In this embodiment, the signal light 48 is a green, yellow, and red LED light, and the flashing colors represent the working states of normal operation, fire warning, and fire alarm, respectively.

[0056] The main control module can process the detection signal of the infrared sensor 46, transmit the detection environment conditions to the signal light, and flash the signal light of the corresponding color according to the detection result to show the current environmental problems to the outside world and make the detection result more intuitive.

[0057] Specifically, the PCB board group 4 includes a mounting plate 43, a first fixing plate 44 and a second fixing plate 45, and the mounting plate 43, the first fixing plate 44 and the second fixing plate 45 are all circuit boards;

[0058] The infrared sensor is fixed on the mounting plate 43, a metal bracket is provided between the first fixing plate 44 and the second fixing plate 45, the first fixing plate 44 and the second fixing plate 45 are spaced and connected by the metal bracket, the mounting plate 43 is fixed by bolts on the side of the first fixing plate 44 away from the second fixing plate 45, and the main control module is installed on the side of the second fixing plate close to the first fixing plate 44. The last fixing plate 44 of the multi-layer PCB circuit board is mainly used as an infrared signal conditioning circuit board, and also plays a certain protective role in the mutual clamping of the bottom circuit main board (second fixing plate 45).

[0059] Optionally, the shell cover 3 of this embodiment is threadedly connected to the shell 1, and a U-shaped groove is provided at the connection between the shell 1 and the housing 3. A circular rubber pad is provided in the U-shaped groove, and an anti-radio frequency coating, a rubber inner film and a heat insulation layer are provided on the inner wall of the shell 1. By providing a circular rubber pad at the connection between the shell and the shell cover 3, the air tightness and sealing effect between the shell cover and the body can be effectively enhanced. The rubber inner mold is fixed on the inner wall of the shell to play a waterproof and dustproof effect.

[0060] Specifically, the main control module integrates a main control circuit, a power supply circuit, an alarm circuit, a communication circuit, and a control circuit for a signal light and an infrared light-emitting tube.

[0061] Wherein, the orientation of the relaxor ferroelectric single crystal is <100> Direction or <111> The working temperature range of the flame detector is -100-110℃, and the working frequency range of the flame detector is 0.1-39.8Hz. The new single crystal has stable physical and chemical properties, long service life, wide temperature detection range, and wide measurement frequency range. It can be used in some harsh environments, which improves the application range of the flame detector.

[0062] In combination with the above preferred implementation modes, Figures 4 to 6 As shown, this embodiment provides a flame detector based on a high Curie point relaxor ferroelectric single crystal, including a shell body and a shell cover. A multi-layer PCB circuit board is arranged inside the shell body, and an infrared sensor 46, a signal light, an infrared light-emitting tube set and a series of hardware circuits are arranged on the circuit board. An optical lens is installed at the top of the shell cover. With the new relaxor ferroelectric single crystal pyroelectric infrared sensor 46 up to 8.5×10 4 V / W has excellent voltage response capability and low signal-to-noise ratio, and performs intelligent algorithm fusion analysis on four-band infrared signals. Compared with traditional flame detectors, it has stronger anti-interference ability and longer alarm distance.

[0063] like Figure 5 and Figure 6 As shown, corresponding tests were conducted based on the flame detector's anti-interference ability and the detection of actual types of combustible combustion. The flame detector's anti-interference ability and detection distance have been significantly improved.

[0064] The preparation method of the specific flame detector comprises the following steps:

[0065] S1: Fix the infrared light-emitting tube in a cylindrical tube with a non-conductive upper end and openings on both sides, and a light-blocking structure is provided on the edge of the cylinder;

[0066] S2: Figure 2As shown in the figure, solder the pins of the infrared light sensor, infrared light-emitting tube and LED signal light to the corresponding pads on the lower surface of the PCB circuit board in sequence, 5 mm apart from each other, and use a brush dipped in board cleaning water to clean the solder joints and the entire board surface;

[0067] S3: Take out the circuit board and the circuit board and insert the connector into the silk-screen position. After the connector is close to the PCB board, solder one pin first. Confirm that the header is tightly attached as a whole and there is no skew, then solder the remaining PIN pins. Apply three-proof paint on all components and solder joints on the front and back surfaces. The coating layer should be intact without holes and uniform in thickness.

[0068] S4: There are small screw holes on the base of the shell. Assemble the circuit board and two M3*15 copper studs through the two vias in the middle of the mainboard to connect the two layers of circuit boards.

[0069] S5: Insert the two terminal wires into the connector on the sensor circuit board, and use round head screws + spring washers and flat washers to lock and connect the circuit boards on each layer;

[0070] S6: Connect the prepared program writer to the detector mainboard through the serial port, burn the flame detector alarm program, and make appropriate band coefficient corrections;

[0071] S7: Connect and fix the connected circuit board and the whole assembly to the screw holes in the shell body, then place a 2.5μm thick sapphire window piece on the shell cover, put a rubber ring on it and tighten it, close the shell base and tighten the bolts.

[0072] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A flame detector based on a high Curie point relaxor ferroelectric single crystal, characterized in that: It comprises a housing (1), a bottom plate (2), a housing cover (3), a PCB board assembly (4), a main control module and an infrared sensor; The bottom plate (2) and the shell cover (3) are respectively mounted on two ends of the shell (1); the PCB board group (4) is arranged inside the shell (1) and has a multi-layer structure; the main control module and the infrared sensor are interconnected and respectively fixed on the PCB board group (4); and an optical lens (31) is mounted on the shell cover (3); The infrared sensor is a relaxor ferroelectric single crystal pyroelectric sensor, and the chemical composition of the relaxor ferroelectric single crystal of the infrared sensor is: (1-xy)Pb(In 1 / 2 Nb 1 / 2 )O3-yPb(Mg 1 / 3 Nb 2 / 3 )O3-xbTiO3-zMn, wherein x=0.20-0.40, y=0.18-0.60, z=0.003-0.

03.

2. A flame detector based on a high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: An infrared light emitting tube (41) is provided at one end of the PCB board group (4) close to the shell cover (3); the infrared light emitting tube (41) is connected to the main control module; the infrared sensor is arranged adjacent to the infrared light emitting tube (41); and the infrared light emitting tube (41) is used to transmit an infrared signal to the infrared sensor.

3. A flame detector based on a high Curie point relaxor ferroelectric single crystal according to claim 2, characterized in that: The PCB board group (4) is provided with a columnar tube for mounting an infrared light-emitting tube (41); one end of the columnar tube away from the PCB board group (4) is provided with a reflection cap (42) and a light-transmitting hole; the infrared signal emitted by the infrared light-emitting tube (41) is reflected to the receiving end of the infrared sensor via the reflection cap (42); and the light-transmitting hole is located between the reflection cap (42) and the emitting end of the infrared light-emitting tube (41).

4. A flame detector based on a high Curie point relaxor ferroelectric single crystal according to claim 3, characterized in that: The infrared light emitting tube (41) is installed at the center of the PCB board group (4) close to one end of the shell cover (3), and there are multiple infrared sensors, each of which is evenly distributed around the infrared light emitting tube (41).

5. A flame detector based on a high Curie point relaxor ferroelectric single crystal according to claim 4, characterized in that: The infrared sensor is a pyroelectric external sensor with a filter. The filter on each infrared sensor has a different light transmission band, and the light transmission band ranges from 2.7 to 5.1 μm.

6. The flame detector based on high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: A signal light is also provided at one end of the PCB board group (4) close to the shell cover (3), and the signal light is connected to the main control module. The flashing colors of the signal lights are different and are used to display the working status of the flame detector.

7. The flame detector based on high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: The PCB board assembly (4) comprises a mounting plate (43), a first fixing plate (44) and a second fixing plate (45); The infrared sensor is fixed on the mounting plate (43); a metal bracket is provided between the first fixing plate (44) and the second fixing plate (45); the first fixing plate (44) and the second fixing plate (45) are spaced and connected by the metal bracket; the mounting plate (43) is fixed to a side of the first fixing plate (44) away from the second fixing plate (45) by bolts; and the main control module is installed on a side of the second fixing plate close to the first fixing plate (44).

8. The flame detector based on high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: The shell cover (3) is threadedly connected to the outer shell (1); a U-shaped groove is provided at the connection between the outer shell (1) and the housing (3); a circular rubber pad is provided in the U-shaped groove; and an anti-radio frequency coating, a rubber inner membrane and a heat insulation layer are provided on the inner wall of the outer shell (1).

9. The flame detector based on high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: The main control module is integrated with a main control circuit, a power supply circuit, an alarm circuit, a communication circuit, and a control circuit for a signal lamp and an infrared light emitting tube.

10. The flame detector based on high Curie point relaxor ferroelectric single crystal according to claim 1, characterized in that: The relaxor ferroelectric single crystal is oriented <100> Direction or <111> direction, the operating temperature range of the flame detector is -100-110°C, and the operating frequency range of the flame detector is 0.1-39.8Hz.

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