High-precision non-dispersive infrared gas sensor

Abstract

The high-precision non-dispersive infrared gas sensor comprises an infrared light source assembly, a gas chamber and a multi-channel detector, the gas chamber comprises an inner tube, a light source fixing seat and a detector fixing seat are respectively mounted at two ends of the inner tube, the inner tube is formed by splicing two semicircular glass tubes, and a gold film is plated on the inner wall of each glass tube. The gas chamber main body of the high-precision non-dispersive infrared gas sensor is formed by splicing the two semicircular glass tubes, the vacuum coating treatment process on the inner walls of the semicircular glass tubes is simple, and the coated inner walls have high smoothness and are uniform and consistent, so that the inner walls have high reflectivity, multiple reflections of infrared light in the gas chamber are enhanced, and the quality of the gas chamber is improved. The measurement precision is improved. The glass material has low thermal conductivity, and can reduce the interference of ambient temperature on gas measurement.

Description

Technical Field

[0001] This utility model belongs to the field of gas detection equipment, and in particular relates to a high-precision non-dispersive infrared gas sensor. Background Technology

[0002] Non-dispersive infrared gas sensors are a commonly used type of infrared optical gas sensor, mainly used to detect the concentration of gases such as CO2, CO, and CH4 in the air. They are characterized by high selectivity, high sensitivity, and high stability.

[0003] Existing non-dispersive infrared gas sensors typically consist of an infrared light source, a gas cell, a multi-channel detector, and electronic signal processing circuitry. The light emitted from the infrared light source is modulated and enters the straight-tube gas cell. At the other end of the gas cell, a multi-channel detector acquires the signal. One channel of the multi-channel detector without characteristic absorption serves as the reference channel, while the remaining spectral channels with characteristic absorption serve as measurement channels. During measurement, the absorbance value of the gas is detected using the measurement channels to calculate the gas concentration. The reference channel is used to detect light energy attenuation and fluctuations in the system, and corrections are made to the measurement channels. In existing technologies, to increase the equivalent optical path through multiple reflections of the beam, the gas cell body is often made of gold-plated metal tubing, and the inner wall needs to be polished to obtain high reflectivity. However, using gold-plated metal tubing as an absorption cell has the following drawbacks:

[0004] (1) Difficulty in internal polishing and difficulty in controlling reflectivity: Polishing the inner wall of metal tubes requires high process requirements, especially for long metal tubes, making it difficult to ensure uniform polishing results. Differences in polishing results can lead to fluctuations in reflectivity between different batches of sensors, thus affecting measurement accuracy. Secondly, metal tubes can only be processed by electroplating, resulting in low reflectivity, low signal-to-noise ratio, and high price;

[0005] (2) Metallic materials have high thermal conductivity and are easily affected by temperature fluctuations: Metals have good thermal conductivity, and the temperature inside the gas chamber will change rapidly when the ambient temperature fluctuates. Such temperature fluctuations may lead to changes in the gas absorption characteristics, thereby affecting the measurement accuracy and stability. Summary of the Invention

[0006] This invention addresses the technical problem of the difficulty in polishing the interior of a gold-plated metal tube in the gas chamber of a non-dispersive infrared gas sensor, which is easily affected by temperature fluctuations. It proposes a high-precision, low-cost, and easy-to-maintain non-dispersive infrared gas sensor.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A high-precision non-dispersive infrared gas sensor includes a light source module, a gas chamber, and a multi-channel detector. The gas chamber includes an inner tube, with a light source mounting base and a detector mounting base installed at both ends of the inner tube, respectively. The inner tube is composed of two semi-circular glass tubes spliced ​​together, and the inner wall of the glass tube is coated with a reflective film.

[0009] Preferably, the inner tube is fitted with an outer tube.

[0010] Preferably, the light source mounting base is provided with an air inlet hole that communicates with the inner tube, and an air inlet nozzle is connected to the air inlet hole; the detector mounting base is provided with an air outlet hole that communicates with the inner tube, and an air outlet nozzle is connected to the air outlet hole.

[0011] Preferably, the light source module includes an infrared light source assembly and an infrared light source base, with the infrared light source base mounted on a light source mounting bracket and the infrared light source assembly mounted on the infrared light source base.

[0012] Preferably, the multi-channel detector includes a detector body, which is installed inside a shielding box, and the shielding box is installed on a detector mounting base.

[0013] Preferably, the system also includes a module mounting plate, on which the light source mounting base, detector mounting base, and outer tube are all mounted.

[0014] Preferably, the module fixing plate has an L-shaped cross-section.

[0015] Preferably, the reflective film is a gold film.

[0016] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0017] 1. The gas chamber of this high-precision non-dispersive infrared gas sensor is composed of two semi-circular glass tubes joined together. The vacuum coating process on the inner wall of the semi-circular glass tubes is simple, and the coated inner wall has high and uniform smoothness, ensuring high reflectivity and enhancing the multiple reflections of infrared light in the gas chamber, thereby improving measurement accuracy. The glass material has low thermal conductivity, which reduces the interference of ambient temperature on gas measurement.

[0018] 2. This infrared gas sensor has a simple manufacturing process, low manufacturing cost, high sensor stability, and an overall modular design, making it portable. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the high-precision non-dispersive infrared gas sensor of this utility model;

[0020] Figure 2 This is an exploded view of the high-precision non-dispersive infrared gas sensor of this utility model;

[0021] In the above figures: 1. Light source module; 11. Infrared light source base; 12. Infrared light source assembly; 2. Air chamber; 21. Inner tube; 22. Outer tube; 23. Light source mounting base; 231. Air inlet; 24. Air inlet nozzle; 25. Detector mounting base; 251. Air outlet; 26. Air outlet nozzle; 3. Multi-channel detector; 31. Detector body; 32. Shielding box; 4. Module mounting plate. Detailed Implementation

[0022] To better understand this utility model, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0023] Example: Figure 1 As shown, a high-precision non-dispersive infrared gas sensor includes an infrared light source assembly 12, a gas chamber 2, and a multi-channel detector 3. The gas chamber 2 includes an inner tube 21 and an outer tube 22 fitted over the inner tube 21. A light source mounting base 23 and a detector mounting base 25 are respectively installed at both ends of the inner tube 21 and the outer tube 22. The outer tube 22 can be made of metal or plastic to protect the inner tube 21. The light source mounting base 23 has an air inlet 231 communicating with the inner tube 21, and an air inlet nozzle 24 is connected to the air inlet 231. The detector mounting base 25 has an air outlet 251 communicating with the inner tube 21, and an air outlet nozzle 26 is connected to the air outlet 251. The inner tube 21 is composed of two glass tubes with a semi-circular cross-section, and the inner wall of the glass tube is coated with a reflective film. The reflective film can be various metal films, preferably a pure gold film with high infrared reflectivity. Before assembly, the inner wall of each semi-circular glass tube is vacuum-coated to form a uniform gold film. The inner wall of the glass tube is smooth, and the vacuum coating process ensures that the inner wall has a very high reflectivity. Furthermore, the coating enhances the multiple reflections of infrared light in the gas chamber 2, improving measurement accuracy.

[0024] The light source module 1 includes an infrared light source assembly 12 and an infrared light source base 11. The infrared light source base 11 is mounted on a light source mounting bracket 23, and the infrared light source assembly 12 is mounted on the infrared light source base 11. The multi-channel detector 3 includes a detector body 31 and a shielding box 32. The detector body 31 is mounted inside the shielding box 32, and the shielding box 32 is mounted on a detector mounting bracket 25. The detector body 31 can be selected according to the detection requirements; in this embodiment, a four-channel detector is used. Infrared light enters the inner tube 21 from one end of the gas chamber 2. After multiple reflections by the gold-plated inner wall of the inner tube 21, the optical path is extended, thereby improving the sensitivity of the gas absorption signal. After the infrared light passes through the gas sample, it is received and detected by the detector at the other end.

[0025] To enable modular assembly, a module fixing plate 4 is also provided. The module fixing plate 4 has an L-shaped cross-section, and the light source fixing seat 23, detector fixing seat 25 and outer tube 22 are all installed on the module fixing plate 4.

[0026] In this embodiment, the high-precision non-dispersive infrared gas sensor's gas chamber 2 is composed of two semi-circular glass tubes joined together. The vacuum coating process on the inner wall of the semi-circular glass tubes is simple, and the coated inner wall has a high and uniform smoothness, ensuring high reflectivity and enhancing the multiple reflections of infrared light in the gas chamber 2, thereby improving measurement accuracy. The glass material has low thermal conductivity, reducing the interference of ambient temperature on gas measurement. The gold plating layer produced by the vacuum coating process on the inner tube 21 has strong corrosion resistance, and its smooth surface is easy to wipe, preventing the accumulation of contaminants that could affect performance and reducing maintenance workload.

[0027] This embodiment presents a high-precision non-dispersive infrared gas sensor. The infrared gas sensor boasts a simple manufacturing process, low cost, and high stability. Its modular design makes it portable.

[0028] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the present invention.

Claims

1. A high precision nondispersive infrared gas sensor characterized by: The application relates to a light source module, a gas chamber and a multi-channel detector, wherein the gas chamber comprises an inner tube, a light source fixing base and a detector fixing base are respectively arranged at two ends of the inner tube, the inner tube is spliced by two semicircular glass tubes, and a reflecting film is coated on the inner wall of the glass tube.

2. The high precision nondispersive infrared gas sensor of claim 1, wherein: An outer tube is sleeved on the inner tube.

3. The high precision nondispersive infrared gas sensor of claim 1, wherein: An air inlet hole is arranged on the light source fixing base and connected with an air inlet nozzle, and an air outlet hole is arranged on the detector fixing base and connected with an air outlet nozzle.

4. The high precision nondispersive infrared gas sensor of claim 1, wherein: The light source module comprises an infrared light source assembly and an infrared light source base, the infrared light source base is arranged on the light source fixing base, and the infrared light source assembly is arranged on the infrared light source base.

5. The high precision nondispersive infrared gas sensor of claim 1, wherein: The multi-channel detector comprises a detector body, the detector body is arranged in a shielding box, and the shielding box is arranged on the detector fixing base.

6. The high precision nondispersive infrared gas sensor of claim 2, wherein: A module fixing plate is further arranged, and the light source fixing base, the detector fixing base and the outer tube are arranged on the module fixing plate.

7. The high precision non-dispersive infrared gas sensor of claim 6, wherein: The module fixing plate is L-shaped in cross section.

8. The high precision nondispersive infrared gas sensor of claim 1, wherein: The reflecting film is a gold film.

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