A gas transmitter based on NDIR principle
By using a planar reflector in the gas transmitter to extend the optical path and install a heat insulation plate to reduce the temperature impact, the problem of insufficient measurement accuracy and sensitivity for low-concentration gases in the prior art is solved, and a high-precision and low-cost gas detection effect is achieved.
Patent Information
- Application Number
- CN202421137140.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-23
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-05-23
AI Technical Summary
When measuring lower concentration gas, existing gas transmitters based on NDIR principle require a longer optical path to improve measurement accuracy and sensitivity. However, the linear long optical path gas chamber is not easily too long due to the instrument structure, resulting in a larger overall size and complex optical structure.
By providing a planar reflector at one end of the air chamber light path tube, the optical path is extended to improve measurement accuracy and sensitivity, and a heat insulation plate is provided in the transmitter housing to reduce temperature influence, simplifying the structure to achieve the advantages of small size and low cost.
High accuracy and sensitivity measurement of low-concentration gases are achieved, and the detection accuracy reaches the PPM level, while reducing the overall size and cost of the equipment.
Smart Images
Figure CN222719433U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of gas transmitters, and in particular to a gas transmitter based on the NDIR principle. Background Art
[0002] The NDIR-based gas transmitter is a gas detection device based on non-dispersive infrared (NDIR) sensing technology. The working principle of the NDIR sensor is to determine the gas concentration by measuring the infrared radiation absorbed or emitted by the measured gas. This sensing technology has the characteristics of high precision and high sensitivity, and can monitor the gas concentration in the environment in real time and accurately.
[0003] The theoretical basis of NDIR technology is the Lambert-Beer law. According to this law, the reduction of light intensity is proportional to the gas concentration and the optical path length, so the concentration of the gas can be calculated by measuring the change in light intensity after passing through the gas. NDIR technology is suitable for the detection of a variety of gases, such as CO, CO2, CH4, SF6, etc.
[0004] According to the Lambert-Beer law, when measuring gases at lower concentrations, a longer optical path is required to improve the measurement accuracy and sensitivity of gas transmitters based on the NDIR principle. This is because the absorption intensity of a gas is proportional to its concentration and optical path length. At lower concentrations, the gas's absorption of infrared light is relatively weak, so in order to obtain sufficient absorption signals, the optical path length needs to be increased to ensure the measurement effect. However, the linear long optical path gas chamber is limited by the instrument structure and cannot be too long. At present, mechanical light cutting structures are mostly used for PPM-level measurements of CO, CO2, CH4, etc. The overall size of the structure is relatively large and the optical structure is complex. Summary of the invention
[0005] In order to improve the measurement accuracy and sensitivity of measuring relatively low concentration gases, the present application provides a gas transmitter based on the NDIR principle.
[0006] The gas transmitter based on the NDIR principle provided in this application adopts the following technical solution:
[0007] A gas transmitter based on the NDIR principle comprises a transmitter housing, a light source transmitter, an air chamber component and an infrared photoelectric detector, wherein the air chamber component is located in the transmitter housing, the air chamber component comprises an air chamber optical path tube, a plug and a plane reflector, the air chamber optical path tube is fixedly connected to the transmitter housing through a mounting seat, two plugs are provided, the two plugs are located at both ends of the air chamber optical path tube and are fixedly connected to the mounting seat at the end of the air chamber optical path tube, the light source transmitter is fixedly connected to one plug, the plane reflector is fixedly connected to another plug, the plane mirror reflector is used to reflect the light path emitted by the light source transmitter, the infrared photoelectric detector is connected to the bottom of the plug on which the light source transmitter is installed, and the infrared photoelectric detector is used to receive infrared light after being absorbed by the gas.
[0008] Optionally, a heat insulation plate is fixedly connected to the transmitter housing, and the heat insulation plate divides the transmitter housing into a first chamber and a second chamber. A main circuit board is provided in the first chamber, and the main circuit board is connected to the heat insulation plate. The light source emitter, air chamber component and infrared photodetector are all located in the second chamber.
[0009] Optionally, two air nozzle connectors are provided on one side of the transmitter housing close to the second chamber, and the air nozzle connectors are connected to the air chamber optical path tube.
[0010] Optionally, the transmitter housing includes a base shell, a wiring shell and a sealing shell, the wiring shell and the sealing shell are respectively located on both sides of the insulation board, the wiring shell is located in the first chamber, and the sealing shell is located in the second chamber, and the wiring shell and the sealing shell are both fixed to the base shell by bolts.
[0011] Optionally, a slot is provided on the bottom shell, and folded edges are integrally provided at the edges of the wiring shell and the sealing shell that are close to each other, and the folded edges of the wiring shell and the sealing shell are inserted into the slot.
[0012] Optionally, a temperature sensor is also connected to the plug at the end of the air chamber optical path tube away from the plane reflector.
[0013] Optionally, a socket is fixedly connected to the outside of the wiring shell, and the socket and the main circuit board are electrically connected by a wire.
[0014] In summary, the present application includes at least one of the following beneficial technical effects:
[0015] 1. The present application sets a plane reflector at one end of the optical path tube of the gas chamber. When the light source emitter emits infrared light, the infrared light path is reflected by the plane reflector and then received by the infrared photodetector. The light signal received by the infrared photodetector is amplified and filtered by the signal processing circuit, and finally outputs an electrical signal corresponding to the concentration of the target gas. The plane reflector can fully extend the optical path in a smaller space, thereby improving the measurement accuracy and sensitivity of the transmitter for low-concentration gas to be measured, and its detection accuracy reaches the PPM level. In addition, the structure of the present application is relatively simple, and compared with the traditional mechanical light cutting structure, it has the advantages of small size and low cost.
[0016] 2. The present application sets a heat insulation board in the transmitter housing, which can effectively block the heat emitted by the main circuit board during operation from being transmitted to the second chamber. Since the absorption spectrum of the gas and the degree of infrared absorption may be affected by temperature, temperature changes may cause deviations in gas concentration measurement results. Therefore, setting a heat insulation board can effectively improve the detection accuracy of the transmitter;
[0017] 3. The present application configures the transmitter housing to include three parts: a bottom housing, a wiring housing, and a sealing housing, which facilitates disassembly, inspection, and maintenance of the transmitter during actual use, thereby having good practicality. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the overall structure of a gas transmitter based on the NDIR principle according to an embodiment of the present application;
[0019] Figure 2 This is an exploded view of a gas transmitter based on the NDIR principle according to an embodiment of the present application;
[0020] Figure 3 is a horizontal cross-sectional view of a gas transmitter based on the NDIR principle according to an embodiment of the present application;
[0021] Figure 4 It is a partially enlarged view of a gas chamber component of a gas transmitter based on the NDIR principle in an embodiment of the present application.
[0022] Explanation of the reference numerals: 1. transmitter housing; 11. bottom housing; 111. card slot; 12. wiring housing; 121. folded edge; 13. sealing housing; 14. heat insulation board; 141. first chamber; 142. second chamber; 15. main circuit board; 16. air nozzle connector; 17. socket; 2. light source transmitter; 3. air chamber component; 31. air chamber optical path tube; 311. mounting seat; 312. temperature sensor; 32. plug; 33. plane reflector; 34. lens; 4. infrared photodetector. DETAILED DESCRIPTION
[0023] The following is combined with Figure 1-4 This application is described in further detail.
[0024] The present application embodiment discloses a gas transmitter based on the NDIR principle. Figure 1-Figure 4 A gas transmitter based on the NDIR principle includes a transmitter housing 1, a light source transmitter 2, a gas chamber component 3 and an infrared photodetector 4.
[0025] Reference Figure 2 and Figure 3 The transmitter housing 1 is in the shape of a rectangular parallelepiped as a whole. The transmitter housing 1 includes a bottom housing 11, a wiring housing 12 and a sealing housing 13. A slot 111 is provided on the side of the bottom housing 11. The edges of the wiring housing 12 and the sealing housing 13 close to each other are integrally provided with a folded edge 121. The folded edges 121 of the wiring housing 12 and the sealing housing 13 are plugged into the slot 111. The wiring housing 12 and the sealing housing 13 are both fixedly connected to the bottom housing 11 by bolts. The wiring housing 12, the sealing housing 13 and the bottom housing 11 surround the rectangular parallelepiped transmitter housing 1. A heat insulation board 14 is fixedly connected to the transmitter housing 1. The heat insulation board 14 divides the transmitter housing 1 into a first chamber 141 and a second chamber 142. The wiring housing 12 and the sealing housing 13 are respectively located on both sides of the heat insulation board 14. The wiring housing 12 is located at the first chamber 141, and the sealing housing 13 is located at the second chamber 142. The first chamber 141 is provided with a main circuit board 15, and the main circuit board 15 and the heat insulation board 14 are fixedly connected by screws.
[0026] Reference Figure 2 , Figure 3 and Figure 4 , the light source emitter 2, the air chamber component 3 and the infrared photodetector 4 are all located in the second chamber 142, and the air chamber component 3 includes an air chamber optical path tube 31, a plug 32 and a plane reflector 33. The air chamber optical path tube 31 is fixedly connected to the bottom shell 11 through a mounting seat 311 by screws, the air chamber optical path tube 31 is horizontally arranged along the axial direction, and the axial direction of the air chamber optical path tube 31 is parallel to the long side of the transmitter housing 1, and there are two plugs 32, which are located at both ends of the air chamber optical path tube 31 and are fixedly connected to the mounting seat 311 at the end of the air chamber optical path tube 31 by screws, the light source emitter 2 is fixedly connected to a plug 32, and a replaceable lens 34 is provided at the emitting end of the light source emitter 2, and the lens 34 is used to filter and obtain the infrared light required for detection, and the light path emitted by the light source emitter 2 can be developed into the air chamber optical path tube 31 through the lens 34 and extend axially of the air chamber optical path tube 31. The plane reflector 33 is fixedly connected to another plug 32. The plane reflector can reflect the light path emitted by the light source transmitter 2. The infrared photodetector 4 is connected to the bottom of the plug 32 where the light source transmitter 2 is installed. The infrared photodetector 4 is used to receive infrared light after being absorbed by the gas.
[0027] Reference Figure 1 and Figure 2 The transmitter housing 1 is provided with two air nozzle joints 16 on the side wall of the sealing shell 13. The two air nozzle joints 16 are respectively located at the two ends of the air chamber optical path tube 31 along the axial direction. One end of the air nozzle joint 16 passes through the sealing shell 13 and is fixedly connected to the mounting seat 311 at the end of the air chamber optical path tube 31. The end of the air nozzle joint 16 is connected to the inside of the air chamber optical path tube 31. One of the air nozzle joints 16 serves as the air inlet of the air chamber optical path tube 31, and the other air nozzle joint 16 serves as the air outlet of the air chamber optical path tube 31. A temperature sensor 312 is also fixedly connected to the plug 32 at the end of the air chamber optical path tube 31 away from the plane reflector 33. The light source emitter 2, the infrared photoelectric detector 4 and the temperature sensor 312 are all electrically connected to the main circuit board 15. A socket 17 is fixedly connected to the outside of the wiring shell 12, and the socket 17 and the main circuit board 15 are electrically connected by wires.
[0028] The implementation principle of a gas transmitter based on the NDIR principle in the embodiment of the present application is as follows: when in use, connect one gas nozzle connector 16 to the gas source to be detected, and start detection when the other gas nozzle connector 16 flows out a gas flow with a stable air pressure. During detection, after the transmitter is powered on through the socket 17, the light source transmitter 2 emits an optical path, and the optical path emitted by the light source transmitter 2 passes through the lens 34 and is filtered to obtain the infrared light required for detection. The infrared appearance extends to the gas chamber optical path tube 31 and the gas chamber optical path tube 31 extends axially. The infrared optical path is emitted to the plane reflector 33 and then reflected. The infrared light is absorbed by the gas to be detected after contacting the gas in the gas chamber optical path tube 31, and then the reflected infrared light is received by the infrared photoelectric detector 4. The optical signal received by the infrared photoelectric detector 4 is amplified and filtered by the signal processing circuit, and finally an electrical signal corresponding to the target gas concentration is output to complete the measurement. The plane reflector 33 can fully extend the optical path in a small space, thereby improving the measurement accuracy and sensitivity of the transmitter for low-concentration gas to be detected, and its detection accuracy reaches the PPM level.
[0029] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A gas transmitter based on the NDIR principle, comprising a transmitter housing (1), a light source transmitter (2), a gas chamber component (3) and an infrared photodetector (4), characterized in that: The air chamber component (3) is located in the transmitter housing (1), and the air chamber component (3) comprises an air chamber optical path tube (31), a plug (32) and a plane reflector (33). The air chamber optical path tube (31) is fixedly connected to the transmitter housing (1) via a mounting seat (311). Two plugs (32) are provided, and the two plugs (32) are located at both ends of the air chamber optical path tube (31) and are fixedly connected to the mounting seat (311) at the end of the air chamber optical path tube (31). The light source transmitter (2) is fixedly connected to one plug (32), and the plane reflector (33) is fixedly connected to another plug (32). The plane reflector (33) is used to reflect the light path emitted by the light source transmitter (2). The infrared photoelectric detector (4) is connected to the bottom of the plug (32) on which the light source transmitter (2) is installed. The light path emitted by the light source emitter (2) is reflected by the plane reflector (33) at the other end of the air chamber light path tube (31) and then received by the infrared photoelectric detector (4).
2. The gas transmitter based on the NDIR principle according to claim 1, characterized in that: A heat insulation board (14) is fixedly connected to the transmitter housing (1), and the heat insulation board (14) divides the transmitter housing (1) into a first chamber (141) and a second chamber (142). A main circuit board (15) is arranged in the first chamber (141), and the main circuit board (15) is connected to the heat insulation board (14). The light source emitter (2), the air chamber component (3) and the infrared photoelectric detector (4) are all located in the second chamber (142).
3. The gas transmitter based on the NDIR principle according to claim 2 is characterized in that: Two air nozzle connectors (16) are provided on one side of the transmitter housing (1) close to the second chamber (142), and the air nozzle connectors (16) are in communication with the air chamber optical path tube (31).
4. The gas transmitter based on the NDIR principle according to claim 2 is characterized in that: The transmitter housing (1) comprises a bottom housing (11), a wiring housing (12) and a sealing housing (13); the wiring housing (12) and the sealing housing (13) are respectively located on both sides of a heat insulation board (14); the wiring housing (12) is located at a first chamber (141), and the sealing housing (13) is located at a second chamber (142); the wiring housing (12) and the sealing housing (13) are both fixedly connected to the bottom housing (11) by bolts.
5. The gas transmitter based on the NDIR principle according to claim 4 is characterized in that: The bottom shell (11) is provided with a card slot (111), and the edges of the wiring shell (12) and the sealing shell (13) close to each other are integrally provided with folded edges (121), and the folded edges (121) of the wiring shell (12) and the sealing shell (13) are inserted into the card slot (111).
6. The gas transmitter based on the NDIR principle according to claim 1, characterized in that: A temperature sensor (312) is also connected to the plug (32) at one end of the air chamber optical path tube (31) away from the plane reflector (33).
7. The gas transmitter based on the NDIR principle according to claim 4 is characterized in that: A socket (17) is fixedly connected to the outside of the wiring shell (12), and the socket (17) and the main circuit board (15) are electrically connected by a wire.