Laser methane gas detection device

Abstract

The utility model discloses a laser methane gas detection device, belongs to the technical field of gas detection, and solves the problem that a laser methane sensor is easily influenced by interference factors such as water mist and greasy dirt in air to interfere gas detection. Comprising a circuit board and a laser reflecting part, the laser reflecting part is installed on the surface of the circuit board, and a laser transmitter and a laser receiver are further installed on the surface of the circuit board; a grating partition plate is arranged in the laser reflecting part, and the laser transmitter and the laser receiver are distributed on the two sides of the grating partition plate; a cavity is formed in the laser reflecting piece, and laser emitted by the laser emitter is reflected to the laser receiver through the inner wall of the laser reflecting piece and the grating partition plate; according to the utility model, greasy dirt and water vapor existing in gas to be detected are filtered through the filter screen, scattered light emitted by laser beams and part of reflected light are shielded by utilizing the grating partition plate in the laser reflecting piece, and the measurement precision and accuracy of gas detection are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of gas detection, and relates to a laser methane gas detection device. Background Technique

[0002] TDLAS (Tunable Diode Laser Absorption Spectroscopy) is the abbreviation of tunable semiconductor laser absorption spectroscopy technology. This technology utilizes the narrow linewidth of the tunable semiconductor laser and the characteristic that the wavelength changes with the injection current to measure single or several absorption lines of molecules that are very close and difficult to distinguish. In the field of gas detection, the TDLAS gas detection technology uses laser wavelength modulation to pass through the characteristic absorption region of the measured gas. When the semiconductor laser emits a laser beam with a specific wavelength through the measured gas, the measured gas absorbs the laser beam, resulting in attenuation of the laser intensity. The attenuation of the laser intensity is proportional to the content of the measured gas. By measuring the attenuation information of the laser intensity, the concentration of the measured gas can be analyzed and obtained.

[0003] However, the material properties of the laser are very sensitive to temperature changes. Even a 1°C change in temperature will cause a 0.1nm drift in the laser wavelength. At the same time, methane gas is mainly used in places such as underground pipelines and kitchens. Interference factors such as water mist and oil stains in the air will affect the light source emitted by the laser, resulting in false alarms of the sensor. Therefore, there is an urgent need for a methane gas detection device that can measure stably, has strong anti-interference ability, and is suitable for narrow spaces such as underground pipelines and kitchens. Summary of the Utility Model

[0004] The technical solution of the utility model is used to solve the problem that the laser methane sensor is easily affected by interference factors such as water mist and oil stains in the air and interferes with gas detection.

[0005] The utility model solves the above technical problems through the following technical solutions:

[0006] A laser methane gas detection device includes a circuit board and a laser reflector. The laser reflector is installed on the surface of the circuit board, and a laser emitter and a laser receiver are also installed on the surface of the circuit board. A grating partition is arranged inside the laser reflector, and the laser emitter and the laser receiver are distributed on both sides of the grating partition. A cavity is formed inside the laser reflector, and the laser emitted by the laser emitter is reflected to the laser receiver through the inner wall of the laser reflector and the grating partition.

[0007] It also includes an upper shell and a lower shell. The bottom opening of the upper shell is clamped with the top opening of the lower shell. A filter screen is installed at the bottom and the inner wall of the lower shell.

[0008] It also includes an adapter and a copper stud. The adapter is fixedly installed on the inner wall of the top of the upper shell. One end of the copper stud is fixed to the adapter by epoxy resin glue, and the other end of the copper stud penetrates through the circuit board and is fixedly connected to the laser reflector. The two copper studs are symmetrically distributed on both sides of the grating partition.

[0009] Furthermore, the circuit board further includes a single-chip microcomputer, a laser driving circuit, a photoelectric conversion and amplification circuit, a PID circuit, a temperature control chip, a temperature and humidity sensor, and a communication circuit. The output end of the single-chip microcomputer is respectively connected to the input end of the communication circuit, the input end of the PID circuit, and the input end of the laser driving circuit. The input end of the single-chip microcomputer is respectively connected to the output end of the temperature and humidity sensor and the output end of the photoelectric conversion and amplification circuit. The output end of the PID circuit is connected to the input end of the temperature control chip. The output end of the laser driving circuit is connected to the input end of the laser emitter, and the output end of the temperature control chip is connected to the control end of the laser emitter. The output end of the laser receiver is connected to the input end of the photoelectric conversion and amplification circuit.

[0010] Furthermore, a clamping groove is provided at the top opening of the upper shell, and a clamping block is provided at the top opening of the lower shell. The lower shell is connected to the clamping groove of the upper shell through the clamping block.

[0011] Furthermore, multiple groups of cables are connected to the side of the circuit board away from the laser reflector. The multiple groups of cables extend to the outside through the top opening of the upper shell, and the top opening of the upper shell is filled with a protective coil.

[0012] Furthermore, the filter screen is made of stainless steel filter screen.

[0013] The advantages of the present utility model are as follows:

[0014] (1) The laser methane gas detection device disclosed by the present utility model is small in size and high in measurement accuracy. It filters the oil and water vapor existing in the gas to be measured through the filter screen, effectively preventing water mist and oil fume. The grating partition in the laser reflector blocks the scattered light and part of the reflected light emitted by the laser beam, avoiding the influence on the waveform signal received by the laser receiver after reflection, and improving the measurement accuracy and accuracy of gas detection.

[0015] (2) The laser methane gas detection device disclosed by the present utility model has high stability and strong anti-interference ability. When the laser emitter emits the waveform signal of the measurement gas, the environmental temperature is collected through the temperature and humidity sensor, and the temperature of the laser is controlled in real time by the PID circuit, ensuring the measurement accuracy and stability of the laser emitter and having strong anti-interference ability. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a laser methane gas detection device according to an embodiment of the present utility model;

[0017] Figure 2 It is a cross-sectional schematic diagram of a laser methane gas detection device according to an embodiment of the present utility model;

[0018] Figure 3 It is a schematic diagram of the circuit board structure of a laser methane gas detection device according to an embodiment of the present utility model;

[0019] Reference numerals: 10, upper housing; 11, lower housing; 20, laser emitter; 21, laser receiver; 30, laser reflector; 31, grating partition; 40, filter screen; 50, copper stud; 51, adapter; 60, protection coil; 70, circuit board; 71, single-chip microcomputer; 72, laser driving circuit; 73, photoelectric conversion and amplification circuit; 74, PID circuit; 75, temperature control chip; 76, temperature and humidity sensor; 77, communication circuit. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0021] The technical solutions of the present utility model will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments:

[0022] Embodiment 1

[0023] As Figure 1-2 shown, specifically, a laser methane gas detection device is disclosed, which includes a circuit board 70 and a laser reflector 30. The laser reflector 30 is installed on the surface of the circuit board 70, and a laser emitter 20 and a laser receiver 21 are also installed on the surface of the circuit board 70; a grating partition 31 is provided inside the laser reflector 30, and the laser emitter 20 and the laser receiver 21 are distributed on both sides of the grating partition 31; a cavity is formed inside the laser reflector 30, and the laser emitted by the laser emitter 20 is reflected to the laser receiver 21 through the inner wall of the laser reflector 30 and the grating partition 31;

[0024] It further includes an upper housing 10 and a lower housing 11. The bottom opening of the upper housing 10 is clamped with the top opening of the lower housing 11. A clamping groove is provided at the top opening of the upper housing 10, and a clamping block is provided at the top opening of the lower housing 11. The lower housing 11 is connected to the clamping groove of the upper housing 10 through the clamping block.

[0025] It further includes an adapter 51 and a copper stud 50. The adapter 51 is fixedly installed on the inner wall of the top of the upper housing 10. One end of the copper stud 50 is fixed on the adapter 51 by epoxy resin glue. The other end of the copper stud 50 penetrates through the circuit board 70 and is fixedly connected to the laser reflector 30. The two copper studs 50 are symmetrically distributed on both sides of the grating partition 31.

[0026] In this embodiment, after the circuit board 70 is welded, it is fixedly connected to the laser transmitter through the copper stud 50, and then the copper stud 50 is fixed on the adapter 51 by epoxy resin glue. After the epoxy resin glue dries, the circuit board 70, the laser reflector 30 and the adapter 51 are installed on the inner wall of the upper housing 10 together.

[0027] A filter screen 40 is installed at the bottom and inner wall of the lower housing 11; in this embodiment, the filter screen 40 is made of stainless steel; gas enters the inside of the housing through the lower housing 11, and methane gas detection is carried out in the laser reflector 30. The filter screen 40 is used to filter oil and water vapor in the air, reducing the influence of environmental factors on methane gas detection. At the same time, the grating partition 31 blocks the scattered light and part of the reflected light of the emitted laser beam, preventing the laser receiver 21 from being affected by the adjacent laser transmitter 20 when receiving the reflected light, and improving the measurement accuracy and accuracy of gas detection. Multiple groups of cables are connected to the side of the circuit board 70 away from the laser reflector 30, and the multiple groups of cables extend to the outside through the top opening of the upper housing 10, and the top opening of the upper housing 10 is filled with a cable grommet 60. In this embodiment, the cable grommet 60 is used to block the top gap of the upper housing 10 to protect and fix the cables.

[0028] As Figure 3 shown, the circuit board 70 further includes a single-chip microcomputer 71, a laser drive circuit 72, a photoelectric conversion and amplification circuit 73, a PID circuit 74, a temperature control chip 75, a temperature and humidity sensor 76, and a communication circuit 77; the output end of the single-chip microcomputer 71 is respectively connected to the input end of the communication circuit 77, the input end of the PID circuit 74, and the input end of the laser drive circuit 72; the input end of the single-chip microcomputer 71 is respectively connected to the output end of the temperature and humidity sensor 76 and the output end of the photoelectric conversion and amplification circuit 73; the output end of the PID circuit 74 is connected to the input end of the temperature control chip 75; the output end of the laser drive circuit 72 is connected to the input end of the laser transmitter 20, and the output end of the temperature control chip 75 is connected to the control end of the laser transmitter 20; the output end of the laser receiver 21 is connected to the input end of the photoelectric conversion and amplification circuit 73.

[0029] As Figure 3As shown, the single-chip microcomputer 71 is connected to the laser driving circuit 72 and is used to send laser driving signals to drive the laser emitter 20 to emit a periodic waveform. The temperature and humidity sensor 76 collects the ambient temperature and humidity signals and sends them to the single-chip microcomputer 71. After the single-chip microcomputer 71 calculates the difference between the set temperature and humidity values and the ambient temperature and humidity values, it sends the result to the PID circuit 74 to adjust the output of the temperature control chip 75 in real time, ensuring that the temperature and humidity of the laser emitter 20 are maintained at the preset operating temperature. The measured gas in the laser reflector 30 absorbs the reflected laser beam. The laser receiver 21 receives the waveform reflected in the laser reflector 30, and the waveform signal is processed by the photoelectric conversion and amplification circuit 73. The single-chip microcomputer 71 determines whether methane gas exists in the environment. At the same time, the single-chip microcomputer 71 also communicates with an external host through the external communication circuit 77.

[0030] Working principle:

[0031] The gas to be measured enters the interior of the housing through the lower housing 11. The filter screen 40 is used to filter out oil, sewage, and water vapor in the air, and methane gas detection is carried out in the laser reflector 30. The single-chip microcomputer 71 drives the laser emitter 20 to emit a waveform signal. The emitted waveform signal is reflected in the laser reflector 30. The grating partition 31 blocks the scattered light and part of the reflected light of the emitted laser beam, preventing the laser receiver 21 from being affected by the adjacent laser emitter 20 when receiving the reflected light. When the emitted laser beam passes through the measured gas, the measured gas absorbs the laser beam, resulting in attenuation of the laser intensity. The laser receiver 21 receives the waveform reflected in the laser reflector 30, and the waveform signal is processed by the photoelectric conversion and amplification circuit 73. The single-chip microcomputer 71 determines whether methane gas exists in the environment. At the same time, the temperature and humidity sensor 76 collects the ambient temperature and humidity signals and sends them to the single-chip microcomputer 71. After the single-chip microcomputer 71 calculates the difference between the set temperature and humidity values and the ambient temperature and humidity values, it sends the result to the PID circuit 74 to adjust the output of the temperature control chip 75 in real time, ensuring that the temperature and humidity of the laser emitter 20 are maintained at the preset operating temperature.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser methane gas detection device, characterized in that: The invention comprises a circuit board (70) and a laser reflector (30), wherein the laser reflector (30) is mounted on the surface of the circuit board (70), and a laser transmitter (20) and a laser receiver (21) are also mounted on the surface of the circuit board (70); a grating partition (31) is arranged inside the laser reflector (30), and the laser transmitter (20) and the laser receiver (21) are distributed on both sides of the grating partition (31); a cavity is formed inside the laser reflector (30), and laser light emitted by the laser transmitter (20) is reflected onto the laser receiver (21) through the inner wall of the laser reflector (30) and the grating partition (31); It also comprises an upper shell (10) and a lower shell (11), wherein the bottom opening of the upper shell (10) is snap-fitted with the top opening of the lower shell (11), and a filter screen (40) is installed on the bottom and inner wall of the lower shell (11); It also includes an adapter (51) and a copper stud (50), wherein the adapter (51) is fixedly mounted on the inner wall at the top of the upper shell (10), one end of the copper stud (50) is fixed to the adapter (51) by epoxy resin glue, and the other end of the copper stud (50) passes through the circuit board (70) and is fixedly connected to the laser reflector (30), and the two copper studs (50) are symmetrically distributed on both sides of the grating partition (31).

2. A laser methane gas detection device according to claim 1, characterized in that: The circuit board (70) further comprises a single-chip microcomputer (71), a laser driving circuit (72), a photoelectric conversion amplifier circuit (73), a PID circuit (74), a temperature control chip (75), a temperature and humidity sensor (76), and a communication circuit (77); the output end of the single-chip microcomputer (71) is respectively connected to the input end of the communication circuit (77), the input end of the PID circuit (74), and the input end of the laser driving circuit (72); the input end of the single-chip microcomputer (71) is respectively connected to the output end of the temperature and humidity sensor (76) and the output end of the photoelectric conversion amplifier circuit (73); the output end of the PID circuit (74) is connected to the input end of the temperature control chip (75); the output end of the laser driving circuit (72) is connected to the input end of the laser transmitter (20), and the output end of the temperature control chip (75) is connected to the control end of the laser transmitter (20); and the output end of the laser receiver (21) is connected to the input end of the photoelectric conversion amplifier circuit (73).

3. A laser methane gas detection device according to claim 1, characterized in that: A card slot is provided at the top opening of the upper shell (10), a card block is provided at the top opening of the lower shell (11), and the lower shell (11) is connected to the card slot of the upper shell (10) via the card block.

4. A laser methane gas detection device according to claim 1, characterized in that: A plurality of cables are connected to a side of the circuit board (70) away from the laser reflector (30), and the plurality of cables extend to the outside through the top opening of the upper shell (10), and the top opening of the upper shell (10) is filled with a protective coil (60).

5. A laser methane gas detection device according to claim 1, characterized in that: The filter screen (40) is made of stainless steel.

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