Wireless laser methane sensor for coal mine

Abstract

The invention belongs to the technical field of methane sensors, and particularly relates to a wireless laser methane sensor for a coal mine. The sensor comprises a sensor shell and a detection assembly installed below the sensor shell. The detection assembly comprises a round shell, an upper cover plate, a lower cover plate and a circuit board installed in the round shell. A light path seat is installed on the lower surface of the circuit board, a detection chamber is arranged on the light path seat, a vortex-shaped light path groove is formed in the detection chamber, a laser and a detector are installed at the two ends of the light path groove respectively, and the laser faces the inner wall of one side of the light path groove; a signal processing module is mounted on the circuit board and is used for carrying out algorithm processing on the optical signal received by the detector; the vortex-shaped light path groove is formed in the light path seat, and a laser signal reaches the detector after being reflected for 50-60 times in the light path groove, so that the laser path is greatly prolonged, energy in laser is fully absorbed by methane, the laser attenuation is increased, and the sensitivity of the sensor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of methane sensors, and in particular to a wireless laser methane sensor for coal mines. Background Art

[0002] Laser methane sensors are used in coal mine roadways, working faces, gob areas, return air roadways, mechanical and electrical chambers, etc. in the coal mine safety detection system to continuously monitor the methane concentration. When the methane concentration exceeds the limit, it can automatically give out sound and light alarms. It can be carried by coal mine underground workers, methane detectors, underground managers, etc., and can also be fixedly used in the above places; among them, the principle of the laser methane sensor is: when the laser passes through the gas to be measured, methane molecules will absorb the laser energy matching their absorption spectral lines, resulting in the attenuation of the transmitted light intensity. According to the Lambert-Beer law, the absorption intensity is proportional to the methane concentration; by detecting the degree of light intensity attenuation and combining calibration data, the concentration can be calculated.

[0003] Existing laser methane sensors are provided with an optical path groove, and multiple groups of lenses are provided in the optical path groove. The laser emits a laser signal, and the laser signal irradiates on the lenses and reaches the detector after 2-3 reflections; however, the existing sensors have the following deficiencies: since the laser only reflects 2-3 times and then reaches the detector, the laser travel distance is short, the methane absorbs less energy in the laser, the laser attenuation is not obvious enough, and the sensor sensitivity is insufficient; secondly, after the sensor is violently vibrated, the angles of the laser, the detector and the lenses may shift, so that the detector cannot receive the laser signal and is easily damaged. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a wireless laser methane sensor for coal mines. By providing a vortex-shaped optical path groove on the optical path seat, the laser travel distance is greatly increased, and the sensitivity of the sensor is improved, aiming to solve the problems in the background art.

[0005] To achieve the above technical purpose, the specific technical solution of the present invention is as follows. A wireless laser methane sensor for coal mines proposed by the present invention includes: a sensor housing and a detection component installed below the sensor housing; the detection component includes a circular housing, an upper cover plate, a lower cover plate, and a circuit board installed in the circular housing; a signal processing module is installed on the circuit board for performing algorithm processing on the optical signal received by the detector.

[0006] As a preferred technical solution of the present invention, reflection layers are provided on both inner walls of the optical path groove, and the laser signal reaches the detector after several reflections in the optical path groove.

[0007] As a preferred technical solution of the present invention, the reflective layer is made of mirror silver material, and the reflective layer is fixedly pasted on the inner wall of the optical path groove.

[0008] As a preferred technical solution of the present invention, the optical path groove includes multiple interconnected arc-shaped grooves, and along the laser propagation direction, the width of the arc-shaped groove in the next section is smaller than that of the arc-shaped groove in the previous section.

[0009] As a preferred technical solution of the present invention, the laser and the detector are respectively installed at the outer end and the inner end of the optical path groove, and a first installation groove is provided on the optical path base for installing the laser; a second installation groove is provided on the optical path base for installing the detector.

[0010] As a preferred technical solution of the present invention, an air inlet is provided at the bottom of the lower cover plate, and a dust-proof net is installed at the air inlet; a wire outlet hole is provided on the upper cover plate, a connecting wire is connected to the circuit board, the connecting wire passes through the wire outlet hole, and a dust-proof plug is installed in the wire outlet hole.

[0011] As a preferred technical solution of the present invention, a temperature sensor, a thermistor, a semiconductor temperature controller, and a photodiode are respectively installed on the circuit board.

[0012] As a preferred technical solution of the present invention, a display, a buzzer, a signal lamp, and a handle are provided on the sensor housing.

[0013] As a preferred technical solution of the present invention, an installation ring for circuit board installation is provided on the inner wall of the circular shell, and dust-proof rings are connected between the circular shell and the upper cover plate and the lower cover plate.

[0014] The beneficial effects of the present invention are as follows: 1. In the present invention, by providing a vortex-shaped optical path groove on the optical path base, the laser signal reaches the detector after 50 - 60 reflections in the optical path groove. Compared with the existing situation where the laser signal reaches the detector after 2 - 3 times, the present invention greatly increases the laser path, enables methane to fully absorb the energy in the laser, increases the laser attenuation, and improves the sensitivity of the sensor.

[0015] 2. The vortex groove of the present invention is provided with multiple arc-shaped grooves, and the width of the arc-shaped groove gradually decreases in the direction close to the detector, so that the width of the last arc-shaped groove is adapted to the diameter of the detector, thereby ensuring that the laser signal can finally reach the detector. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a wireless laser methane sensor for coal mines proposed by the present invention.

[0017] Figure 2 It is a schematic structural diagram of the detection component proposed by the present invention.

[0018] Figure 3 This is a sectional view of the detection component proposed by the present invention.

[0019] Figure 4 This is a structural diagram of the circuit board proposed by the present invention.

[0020] Figure 5 This is a structural diagram of the optical path seat proposed by the present invention.

[0021] In the figure: 1, sensor housing; 2, detection component; 21, round shell; 22, upper cover plate; 221, wire outlet hole; 222, dust plug; 223, connecting wire; 23, lower cover plate; 231, air inlet; 24, circuit board; 241, optical path seat; 242, detection chamber; 243, optical path groove; 244, reflection layer; 245, first installation groove; 246, laser; 247, second installation groove; 248, detector; 249, temperature sensor; 2410, semiconductor temperature controller; 2411, thermistor; 2412, photodiode; 2413, signal processing module; 25, dust screen; 26, dust ring; 27, installation ring; 3, handle; 4, display; 5, buzzer; 6, signal lamp. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0023] This embodiment discloses a wireless laser methane sensor for coal mines, as Figures 1 - 5 shown, including: a sensor housing 1 and a detection component 2 installed below the sensor housing 1; a control circuit board is provided inside the sensor housing 1, and a display 4, a buzzer 5, a signal lamp 6 and a handle 3 are provided on the sensor housing 1. The display 4 is used to display information such as temperature and methane concentration. If the methane concentration exceeds the normal value, the buzzer 5 will automatically give an alarm and the signal lamp 6 will flash, sending out a signal in the first time.

[0024] As Figures 2 - 3As shown in the figure, the detection component 2 includes a circular shell 21, an upper cover plate 22, a lower cover plate 23, and a circuit board 24 installed inside the circular shell 21. The upper cover plate 22 and the lower cover plate 23 are both fixedly connected to the circular shell 21 by means of clamping; among them, an air inlet 231 is provided at the bottom of the lower cover plate 23, and methane gas enters the inside of the circular shell 21 through the air inlet 231. A dust-proof net 25 is installed at the air inlet 231 to prevent dust from entering the inside of the circular shell 21. The dust-proof net 25 can be disassembled and cleaned regularly; an outgoing line hole 221 is provided on the upper cover plate 22, and a connecting line 223 is connected to the circuit board 24. The connecting line 223 passes through the outgoing line hole 221 and extends into the sensor housing 1. The connecting line 223 is connected to the internal circuit board, and a dust-proof plug 222 is installed in the outgoing line hole 221. The dust-proof plug 222 is made of rubber material, and the connecting line 223 passes through the dust-proof plug 222.

[0025] Preferably, an installation ring 27 for installing the circuit board 24 is provided on the inner wall of the circular shell 21. Bolt holes are provided on the installation ring 27, and the circuit board 24 is fixedly installed on the installation ring 27 by bolts. Moreover, dust-proof rings 26 are connected between the circular shell 21 and the upper cover plate 22 and the lower cover plate 23 respectively. The dust-proof rings 26 are used to prevent dust from entering the inside of the circular shell 21.

[0026] As Figures 4 - 5 shown in the figure, an optical path seat 241 is installed on the lower surface of the circuit board 24. The optical path seat 241 is circular and faces the air inlet 231. A detection chamber 242 is provided on the optical path seat 241. After the gas enters the circular shell 21 through the air inlet 231, it then enters the detection chamber 242. A spiral optical path groove 243 is provided in the detection chamber 242. A laser 246 and a detector 248 are respectively installed at both ends of the optical path groove 243. Among them, the laser 246 and the detector 248 are respectively installed at the outer end and the inner end of the optical path groove 243. The laser 246 emits a laser signal, and the laser signal reaches the detector 248 after being reflected several times in the optical path groove 243. Moreover, a first installation groove 245 is provided on the optical path seat 241 for installing the laser 246; a second installation groove 247 is provided on the optical path seat 241 for installing the detector 248; among them, the laser 246 faces the inner wall of the optical path groove 243, and the laser signal emitted by the laser 246 directly irradiates on the inner wall of the optical path groove 243. In this embodiment, the number of reflections of the laser signal in the optical path groove 243 is between 50 and 60 times, as opposed to 2 to 3 times in the prior art, which greatly increases the propagation distance of the laser, enabling the methane gas to fully absorb the energy in the laser. Even when the methane concentration is relatively low, the attenuation of the laser is also relatively obvious, thereby improving the sensitivity of the sensor; among them, a signal processing module 2413 is installed on the circuit board 24 to perform algorithm processing on the optical signal received by the detector 248, calculate the attenuation degree of the laser signal, and thus obtain the methane concentration in the air.

[0027] Among them, reflective layers 244 are provided on both inner walls of the optical path groove 243. The laser signal reaches the detector 248 after 50-60 reflections in the optical path groove 243. In this embodiment, the reflective layer 244 is made of mirror silver with a high reflectivity curved surface. The reflectivity of the mirror silver material can reach 97%. The reflective layer 244 is fixedly pasted on the inner wall of the optical path groove 243 with glue. It should be noted that since the laser signal will attenuate each time it is reflected by the reflective layer 244, when measuring the methane concentration, the laser signal received by the detector 248 should be compared with the laser signal received when the methane gas concentration is 0. The difference between the two is the attenuation value of the laser signal caused by the methane gas. Therefore, when writing the algorithm, it is necessary to measure the magnitude of the laser signal value received by the detector 248 when the methane concentration is 0 and write this value into the algorithm formula.

[0028] Preferably, the optical path groove 243 includes multiple interconnected arc-shaped grooves. Along the laser propagation direction, the width of the next arc-shaped groove is smaller than that of the previous arc-shaped groove. In this embodiment, there are three arc-shaped grooves, and the widths of the three arc-shaped grooves are 1 cm, 0.75 cm, and 0.5 cm respectively. The number of turns of the optical path groove 243 is 1.5 turns, so that the width of the optical path groove 243 near the detector 248 is smaller, and the width of the end of the optical path groove 243 is nearly the same as the diameter of the detector 248. Even if there is a slight deviation in the installation angle between the detector 248 and the laser 246, the laser signal can finally be reflected onto the detector 248.

[0029] Preferably, a temperature sensor 249, a thermistor 2411, a semiconductor temperature controller 2410, and a photodiode 2412 are respectively installed on the circuit board 24. The temperature sensor 249 is used to detect the air temperature, and the thermistor 2411 and the semiconductor temperature controller 2410 are used to adjust the internal temperature of the detection component 2, avoiding the influence of a large temperature change range on the laser signal.

[0030] Working principle: In this embodiment, the laser 246 emits a laser signal that irradiates on the reflective layer 244 on the inner wall of the optical path groove 243. The laser signal reaches the detector 248 after 50-60 reflections. The detector 248 sends the received laser signal to the signal processing module 2413. The signal processing module 2413 performs algorithm processing on the laser signal to calculate the laser attenuation value caused by the methane gas, thereby calculating the methane concentration in the air. In this embodiment, the optical path travel is greatly increased, so that the methane gas can fully absorb the energy in the laser. Even when the methane gas concentration is low, the laser attenuation degree is also obvious, thus improving the sensitivity of the sensor.

[0031] Finally, it should be noted that in the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0032] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wireless laser methane sensor for coal mines, characterized in that, Comprising: A sensor housing (1) and a detection component (2) mounted below the sensor housing (1); The detection component (2) includes a circular shell (21), an upper cover plate (22), a lower cover plate (23), and a circuit board (24) mounted inside the circular shell (21); A light path seat (241) is mounted on the lower surface of the circuit board (24). A detection chamber (242) is provided on the light path seat (241). A spiral light path groove (243) is provided in the detection chamber (242). A laser (246) and a detector (248) are respectively mounted at both ends of the light path groove (243). The laser (246) faces the inner wall on one side of the light path groove (243); A signal processing module (2413) is mounted on the circuit board (24) for performing algorithm processing on the optical signal received by the detector (248).

2. The wireless laser methane sensor for coal mines according to claim 1, wherein, Reflective layers (244) are provided on both inner walls of the light path groove (243). The laser signal reaches the detector (248) after being reflected several times in the light path groove (243).

3. The wireless laser methane sensor for coal mines according to claim 2, characterized in that, The reflective layer (244) is made of mirror silver material and is pasted and fixed on the inner wall of the light path groove (243).

4. The wireless laser methane sensor for coal mines according to claim 3, characterized in that, The light path groove (243) includes multiple interconnected arc-shaped grooves. Along the laser propagation direction, the width of the arc-shaped groove in the next section is smaller than that of the arc-shaped groove in the previous section.

5. The wireless laser methane sensor for coal mines according to claim 4, characterized in that, The laser (246) and the detector (248) are respectively mounted at the outer end and the inner end of the light path groove (243). A first mounting groove (245) is provided on the light path seat (241) for mounting the laser (246); a second mounting groove (247) is provided on the light path seat (241) for mounting the detector (248).

6. The wireless laser methane sensor for coal mines according to claim 5, characterized in that, An air inlet (231) is provided at the bottom of the lower cover plate (23). A dust-proof net (25) is mounted at the air inlet (231); an outlet hole (221) is provided on the upper cover plate (22). A connecting wire (223) is connected to the circuit board (24). The connecting wire (223) passes through the outlet hole (221), and a dust-proof plug (222) is mounted in the outlet hole (221).

7. The wireless laser methane sensor for coal mines according to claim 6, characterized in that, A temperature sensor (249), a thermistor (2411), a semiconductor temperature controller (2410), and a photodiode (2412) are respectively mounted on the circuit board (24).

8. The wireless laser methane sensor for coal mines according to claim 7, characterized in that, A display (4), a buzzer (5), a signal lamp (6), and a handle (3) are provided on the sensor housing (1).

9. The wireless laser methane sensor for coal mines according to claim 8, characterized in that, An installation ring (27) for mounting the circuit board (24) is provided on the inner wall of the circular shell (21). Dust-proof rings (26) are connected between the circular shell (21) and the upper cover plate (22) and the lower cover plate (23).

Images