Gas detection device based on NDIR

Abstract

The utility model provides a gas detection device based on NDIR, which comprises a PCB (printed circuit board), a bottom plate and an upper cover, the upper cover is provided with an optical cavity, the periphery of the bottom plate is embedded with the inner wall of a coaming to seal the optical cavity, the bottom plate is provided with a first through hole and a second through hole, an infrared light source on the PCB penetrates through the first through hole to extend into the optical cavity, and the infrared light source on the PCB penetrates through the second through hole to extend into the optical cavity. The dual-channel infrared sensor penetrates through the second through hole and extends into the light cavity; the dual-channel infrared sensor is provided with a first channel and a second channel, the cover plate is provided with a V-shaped reflecting plate and a light gathering plate, the light gathering plate is provided with a first reflecting surface corresponding to the first channel and a second reflecting surface corresponding to the second channel, the two sides of the light gathering plate are respectively provided with a main detection air hole, and the cover plate is provided with a plurality of auxiliary detection air holes. On the basis of an original main detection gas hole, a plurality of auxiliary detection gas holes are additionally formed in the cover plate, the gas exchange rate is increased, meanwhile, the light gathering plate is designed to be provided with double reflecting surfaces, and the increase of infrared light loss caused by the auxiliary detection gas holes is made up.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection, in particular to a gas detection device based on NDIR. Background Art

[0002] With the advancement of gas technology, non-dispersive infrared (NDIR) gas detection technology has been widely used due to its high sensitivity, high selectivity and stability.

[0003] In NDIR gas detection devices, the design of the gas chamber directly affects the performance of gas detection. In the design of the gas chamber of traditional NDIR gas detection devices, optical components such as focusing cone plates, oblique reflectors, V-shaped reflectors and arc reflectors are usually used to optimize the interaction between the infrared light emitted by the infrared light source and the gas being measured. These optical components can reflect the infrared light multiple times, ensuring that the infrared light can pass through the gas area being measured multiple times and be projected onto the photosensitive chip multiple times, thereby enhancing the strength of the detection signal and improving the sensitivity of the detection.

[0004] However, in practical applications, the existing NDIR gas detection device gas chamber design has an obvious shortcoming: the detection air holes are often located below the two sides of the focusing cone plate. Due to the limited area of ​​this location, the detection air holes are small and the gas exchange rate is slow. This not only limits the flow of gas entering the gas chamber, but also affects the uniformity and stability of the measured gas concentration inside the gas chamber, thereby prolonging the time for the gas chamber to detect the actual concentration of the gas and reducing the detection response speed. Utility Model Content

[0005] Based on this, the purpose of the present invention is to provide a NDIR gas detection device to solve the technical problems mentioned in the above background technology.

[0006] The utility model proposes a gas detection device based on NDIR, comprising a PCB board, a bottom plate and an upper cover arranged in sequence from bottom to top, the upper cover comprising a cover plate and a surrounding plate arranged at the periphery of the cover plate, the cover plate and the surrounding plate are combined to form an optical cavity, the periphery of the bottom plate is embedded with the inner wall of the surrounding plate to close the optical cavity, a first through hole and a second through hole are opened on the bottom plate, an infrared light source and a dual-channel infrared sensor are arranged on the PCB board, the infrared light source extends into the optical cavity through the first through hole, and the dual-channel infrared sensor extends into the optical cavity through the second through hole;

[0007] The dual-channel infrared sensor has a first channel and a second channel that are adjacent to each other. A V-shaped reflecting plate corresponding to the infrared light source and a focusing plate corresponding to the dual-channel infrared sensor are provided on one side of the cover plate located in the optical cavity. A first reflecting surface corresponding to the first channel and a second reflecting surface corresponding to the second channel are provided on the focusing plate. Main detection air holes are provided on one side of the focusing plate adjacent to the first reflecting surface and on one side adjacent to the second reflecting surface, respectively. A plurality of auxiliary detection air holes are provided on the cover plate.

[0008] Furthermore, in the NDIR-based gas detection device, the first reflection surface is an arc surface or a conical surface, and the second reflection surface has the same structure as the first reflection surface.

[0009] Furthermore, in the NDIR-based gas detection device, the V-shaped reflection plate has a third reflection surface and a fourth reflection surface that are arranged opposite to each other, and the infrared light source is located between the third reflection surface and the fourth reflection surface.

[0010] Furthermore, the NDIR-based gas detection device, wherein the enclosure includes a first enclosure, a second enclosure, a third enclosure and a fourth enclosure connected in sequence, the V-shaped reflector is arranged at the angle between the second enclosure and the third enclosure, and the focusing plate is arranged at the angle between the first enclosure and the second enclosure.

[0011] Furthermore, in the NDIR-based gas detection device, a first arc-shaped reflection plate is provided at the angle between the first surrounding edge and the fourth surrounding edge, and a second arc-shaped reflection plate is provided at the angle between the fourth surrounding edge and the third surrounding edge.

[0012] Furthermore, in the NDIR-based gas detection device, an oblique reflection plate is provided on the fourth surrounding edge, and the oblique reflection plate is located between the first curved reflection plate and the second curved reflection plate, and the inclined surface of the oblique reflection plate gradually protrudes from the first curved reflection plate toward the second curved reflection plate.

[0013] Furthermore, in the NDIR-based gas detection device, a plurality of the auxiliary detection holes are located between the first arc-shaped reflection plate and the second arc-shaped reflection plate, and the plurality of the auxiliary detection holes are arranged at intervals along the length direction of the fourth surrounding edge.

[0014] Furthermore, in the NDIR-based gas detection device, the number of the secondary detection holes is an even number.

[0015] Furthermore, in the NDIR-based gas detection device, the upper surface of the cover plate is covered with a waterproof and breathable membrane.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] On the basis of retaining the original main detection air holes, several additional auxiliary detection air holes are opened on the cover plate to increase the gas exchange rate. At the same time, in order to reduce the increase in infrared light loss caused by the auxiliary detection air holes, the focusing plate is designed as a double reflection surface to improve the energy reception of the dual-channel infrared sensor. In this way, the gas detection efficiency can be improved without affecting the original gas detection accuracy, and fast and accurate gas detection can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an exploded view of the NDIR-based gas detection device in the present utility model;

[0019] Figure 2 It is a schematic diagram of the specific structure of the upper cover in the utility model;

[0020] Description of main component symbols:

[0021] 10. PCB board; 20. bottom plate; 30. upper cover; 31. cover plate; 32. enclosure; 21. first perforation; 22. second perforation; 11. infrared light source; 12. dual-channel infrared sensor; 121. first channel; 122. second channel; 41. V-shaped reflector; 42. focusing plate; 421. first reflective surface; 422. second reflective surface; 423. main detection air hole; 50. auxiliary detection air hole; 411. third reflective surface; 412. fourth reflective surface; 321. first surrounding edge; 322. second surrounding edge; 323. third surrounding edge; 324. fourth surrounding edge; 61. first arc reflector; 62. second arc reflector; 63. oblique reflector; 70. waterproof breathable membrane; 80. air inlet cavity.

[0022] The following specific implementation manner will further illustrate the present utility model in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] See also Figure 1 and Figure 2 The NDIR-based gas detection device in the utility model comprises a PCB board 10, a bottom plate 20 and an upper cover 30 arranged in sequence from bottom to top, the upper cover 30 comprises a cover plate 31, and a surrounding plate 32 arranged at the periphery of the cover plate 31, the cover plate 31 and the surrounding plate 32 are combined to form an optical cavity, the periphery of the bottom plate 20 is engaged with the inner wall of the surrounding plate 32 to close the optical cavity, the bottom plate 20 is provided with a first through hole 21 and a second through hole 22, the PCB board 10 is provided with an infrared light source 11 and a dual-channel infrared sensor 12, the infrared light source 11 extends into the optical cavity through the first through hole 21, and the dual-channel infrared sensor 12 extends into the optical cavity through the second through hole 22;

[0027] The dual-channel infrared sensor 12 has a first channel 121 and a second channel 122 adjacent to each other. A V-shaped reflecting plate 41 corresponding to the infrared light source 11 and a focusing plate 42 corresponding to the dual-channel infrared sensor 12 are provided on one side of the cover plate 31 located in the optical cavity. A first reflecting surface 421 corresponding to the first channel 121 and a second reflecting surface 422 corresponding to the second channel 122 are provided on the focusing plate 42. Main detection air holes 423 are provided on one side of the focusing plate 42 adjacent to the first reflecting surface 421 and on one side adjacent to the second reflecting surface 422, respectively. A plurality of auxiliary detection air holes 50 are provided on the cover plate 31.

[0028] On the basis of retaining the original main detection air hole 423, a plurality of auxiliary detection air holes 50 are additionally opened on the cover plate 31 to increase the gas exchange rate. At the same time, in order to reduce the increase in infrared light loss caused by the auxiliary detection air holes 50, the focusing plate 42 is designed as a double reflection surface to improve the infrared light reception of the dual-channel infrared sensor 12. In this way, the gas detection efficiency can be improved without affecting the original gas detection accuracy, and fast and accurate gas detection can be achieved, thereby effectively reducing the T90 time.

[0029] What needs to be explained about T90 time is that T90 time refers to the time required for the gas detection device to read zero and rise to 90% of the concentration of the detected gas in the environment. As one of the core parameters affecting the performance of the gas detection device, it directly determines the response speed and sensitivity of the detection device to the detected gas. Therefore, reducing T90 time can greatly improve the performance of the gas detection device.

[0030] In addition, the actual detection principle of the gas detection device is: the infrared light emitted by the infrared light source 11 is reflected multiple times in the optical cavity, so that the gas in the optical cavity effectively absorbs the infrared light, and finally reaches the dual-channel infrared sensor 12 to generate a signal voltage difference, thereby realizing the detection of gas concentration. The entire process is realized in the optical cavity. The reading of the gas detection device is actually the gas concentration in the optical cavity. The detected gas in the environment needs to pass through the main detection air hole 423 and the auxiliary detection air hole 50 in the detection device to enter the optical cavity. Therefore, in order to truly detect the concentration of the measured gas in the environment, it is necessary to wait for the measured gas in the environment to be completely exchanged with the air inside the optical cavity or reach 90% exchange. This period of time is almost equivalent to the T90 time.

[0031] Specifically, the first reflecting surface 421 is an arc surface or a conical surface, and the second reflecting surface 422 has the same structure as the first reflecting surface 421 .

[0032] For further information, see Figure 2, the enclosure 32 includes a first enclosure 321, a second enclosure 322, a third enclosure 323 and a fourth enclosure 324 connected in sequence, the V-shaped reflector 41 is arranged at the angle between the second enclosure 322 and the third enclosure 323, and the focusing plate 42 is arranged at the angle between the first enclosure 321 and the second enclosure 322. It can be understood that the focusing plate 42 is used to reflect the light penetrating the dual-channel infrared sensor 12 back to the first channel 121 and the second channel 122, so as to reduce the loss of infrared light. Specifically, the first reflection surface 421 on the focusing plate 42 is used to guide the infrared light into the first channel 121, and the second reflection surface 422 is used to guide the infrared light into the second channel 122. Among them, the first channel 121 is used as the main detection channel, and the second channel 122 is used as the reference detection channel. Through the mutual compensation between the two, a series of performances such as gas detection accuracy, resolution, service life, and anti-interference can be greatly improved.

[0033] The V-shaped reflector 41 has a third reflective surface 411 and a fourth reflective surface 412 that are arranged opposite to each other, and the infrared light source 11 is located between the third reflective surface 411 and the fourth reflective surface 412. The third reflective surface 411 and the fourth reflective surface 412 are used to guide the infrared light emitted by the infrared light source 11 to propagate along a predetermined path, avoiding unnecessary direct or reflected interference, thereby improving the accuracy and reliability of detection. In this embodiment, the angle formed between the third reflective surface 411 and the fourth reflective surface 412 is an acute angle.

[0034] Furthermore, a first arc-shaped reflective plate 61 is provided at the angle between the first surrounding edge 321 and the fourth surrounding edge 324, and a second arc-shaped reflective plate 62 is provided at the angle between the fourth surrounding edge 324 and the third surrounding edge 323. In this embodiment, the first arc-shaped reflective plate 61 and the second arc-shaped reflective plate 62 are arranged relative to each other in an eight-shaped shape. It can be understood that during the gas detection process, the infrared light source 11 emits infrared light, which passes through the gas to be measured in the optical cavity, enters the measurement channel of the dual-channel infrared sensor 12 after being reflected by the first arc-shaped reflective plate 61 and the second arc-shaped reflective plate 62, and generates an electrical signal, which is converted into a digital signal by the processing module on the PCB board 10, and finally the digital signal is converted into gas concentration data.

[0035] Furthermore, an oblique reflection plate 63 is provided on the fourth surrounding edge 324, and the oblique reflection plate 63 is located between the first curved reflection plate 61 and the second curved reflection plate 62, and the oblique surface of the oblique reflection plate 63 gradually protrudes from the first curved reflection plate 61 toward the second curved reflection plate 62. The oblique reflection plate 63 is used to combine the first curved reflection plate 61 and the second curved reflection plate 62 to increase the number of reflections of infrared light in the optical cavity, so that the gas in the optical cavity effectively absorbs the infrared light, making the data measured by the dual-channel infrared sensor 12 more accurate.

[0036] Furthermore, the plurality of auxiliary detection air holes 50 are located between the first arc-shaped reflection plate 61 and the second arc-shaped reflection plate 62 , and the plurality of auxiliary detection air holes 50 are arranged at intervals along the length direction of the fourth surrounding edge 324 .

[0037] Illustratively, in this embodiment, the number of the auxiliary detection air holes 50 is an even number, specifically 4 rectangular air holes. Of course, the number may also be 2 or 6. This embodiment is only an example and not a limitation.

[0038] It can be understood that the number of openings of the auxiliary detection air hole 50 is an even number, so that the gas can enter and exit one by one, and the convection rate is increased. Secondly, by adding 4 rectangular air holes, not only the opening area is increased, but also the number of convection holes is increased. On the whole, the exchange rate between the ambient gas being measured and the optical cavity air can be increased, the T90 time can be greatly reduced, the reading waiting time can be reduced, and the true concentration of the ambient gas being measured can be accurately reflected.

[0039] It should be noted that, although the air exchange rate in the optical cavity is increased after the auxiliary detection air hole 50 is added, the loss of infrared light emitted by the infrared light source 11 is also increased. In order to reduce the infrared light loss caused by the opening of the auxiliary detection air hole 50, the present embodiment changes the focusing plate 42 into a double reflection surface design, which reduces the infrared light loss from the design principle. The double reflection surfaces correspond to the two channels of the dual-channel infrared sensor 12 respectively. Compared with the original single reflective cone surface, the infrared light loss is reduced and the voltage signal generation size is increased.

[0040] It can be seen that by adding four auxiliary detection holes 50, the cooperation between the double-reflective surface focusing plate 42 and the dual-channel infrared sensor 12, rapid and accurate detection of the gas to be measured in the environment can be achieved, greatly improving the performance of the gas detection device.

[0041] Furthermore, the upper surface of the cover plate 31 is covered with a waterproof breathable membrane 70. It can be understood that the waterproof breathable membrane 70 is used to allow gas to enter the optical cavity through the main detection air hole 423 and / or the auxiliary detection air hole 50, while preventing external moisture from entering, ensuring the reliable operation of the gas detection device and reducing damage to the device caused by moisture or water ingress.

[0042] See also Figure 1 The upper surface of the cover plate 31 is concave to form an air inlet cavity 80 connected to the main detection air hole 423. The air inlet cavity 80 helps to stabilize the flow rate and flow direction of the gas, ensuring that the gas can enter the optical cavity smoothly and orderly through the main detection air hole 423.

[0043] In summary, the NDIR-based gas detection device in the above-mentioned embodiment of the utility model, on the basis of retaining the original main detection air hole 423, additionally opens a plurality of auxiliary detection air holes 50 on the cover plate 31, thereby improving the gas exchange rate. At the same time, in order to reduce the increase in infrared light loss caused by the auxiliary detection air holes 50, the focusing plate 42 is designed as a double reflection surface to improve the energy reception of the dual-channel infrared sensor 12. In this way, the gas detection efficiency can be improved without affecting the original gas detection accuracy, thereby achieving fast and accurate gas detection.

[0044] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0045] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A gas detection device based on NDIR, comprising a PCB board, a bottom plate and an upper cover arranged in sequence from bottom to top, characterized in that: The upper cover includes a cover plate and a surrounding plate arranged at the periphery of the cover plate, the cover plate and the surrounding plate are combined to form a light cavity, the periphery of the bottom plate is embedded with the inner wall of the surrounding plate to close the light cavity, the bottom plate is provided with a first through hole and a second through hole, the PCB board is provided with an infrared light source and a dual-channel infrared sensor, the infrared light source extends into the light cavity through the first through hole, and the dual-channel infrared sensor extends into the light cavity through the second through hole; The dual-channel infrared sensor has a first channel and a second channel that are adjacent to each other. A V-shaped reflecting plate corresponding to the infrared light source and a focusing plate corresponding to the dual-channel infrared sensor are provided on one side of the cover plate located in the optical cavity. A first reflecting surface corresponding to the first channel and a second reflecting surface corresponding to the second channel are provided on the focusing plate. Main detection air holes are provided on one side of the focusing plate adjacent to the first reflecting surface and on one side adjacent to the second reflecting surface, respectively. A plurality of auxiliary detection air holes are provided on the cover plate.

2. The NDIR-based gas detection device according to claim 1, characterized in that: The first reflecting surface is an arc surface or a conical surface, and the second reflecting surface has the same structure as the first reflecting surface.

3. The NDIR-based gas detection device according to claim 1, characterized in that: The V-shaped reflection plate has a third reflection surface and a fourth reflection surface that are arranged opposite to each other, and the infrared light source is located between the third reflection surface and the fourth reflection surface.

4. The NDIR-based gas detection device according to claim 1, characterized in that: The enclosure includes a first enclosure, a second enclosure, a third enclosure and a fourth enclosure connected in sequence, the V-shaped reflector is arranged at the angle between the second enclosure and the third enclosure, and the focusing plate is arranged at the angle between the first enclosure and the second enclosure.

5. The NDIR-based gas detection device according to claim 4, characterized in that: A first arc-shaped reflective plate is provided at an angle between the first surrounding edge and the fourth surrounding edge, and a second arc-shaped reflective plate is provided at an angle between the fourth surrounding edge and the third surrounding edge.

6. The NDIR-based gas detection device according to claim 5, characterized in that: An oblique reflection plate is provided on the fourth surrounding edge, and the oblique reflection plate is located between the first arc reflection plate and the second arc reflection plate. The oblique surface of the oblique reflection plate gradually protrudes from the first arc reflection plate toward the second arc reflection plate.

7. The NDIR-based gas detection device according to claim 5, characterized in that: The plurality of auxiliary detection air holes are located between the first arc-shaped reflection plate and the second arc-shaped reflection plate, and the plurality of auxiliary detection air holes are arranged at intervals along the length direction of the fourth surrounding edge.

8. The NDIR-based gas detection device according to claim 1, characterized in that: The number of the secondary detection pores is an even number.

9. The NDIR-based gas detection device according to claim 1, characterized in that: The upper surface of the cover plate is covered with a waterproof and breathable membrane.

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