Particulate matter concentration detection module

Abstract

The utility model discloses a kind of particulate matter concentration detection modules, including shell, detecting element, fan and circuit board;Shell includes main body, upper cover and lower cover, the first side of main body is equipped with airflow passage and light beam passage, airflow passage and light beam passage meet, lower cover cover is equipped in the first side of main body, lower cover inboard is equipped with dustproof sealing membrane, dustproof sealing membrane extrusion between the first side of main body and lower cover, upper cover cover is equipped in the second side of main body, air inlet and exhaust port are equipped on it;Detecting element includes light emitter and light receiver, light emitter emits light beam along light beam passage, light receiver is equipped at the meeting place of airflow passage and light beam passage;Fan is arranged in shell, for introducing airflow of outside into airflow passage by air inlet, and make the airflow that enters airflow passage by exhaust port discharge;Circuit board is arranged in shell, detecting element and / or fan electrically connected circuit board.The particulate matter concentration detection module of the utility model can improve the detection accuracy.

Description

Technical Field

[0001] This utility model relates to the field of particulate matter concentration detection technology, specifically, to a particulate matter concentration detection module. Background Technology

[0002] A laser dust concentration detection device is a device that uses MIE scattering theory to count or measure the mass concentration of suspended particles in the air. A typical dust concentration detection device includes a fluid flow channel, a laser emitting component for generating laser light, and a laser detection component for sensing the scattered light. The fluid to be tested flows in the fluid flow channel. When dust particles in the fluid flow over the laser detection component, they are irradiated by the laser, generating scattered light. The laser detection component receives the scattered light, and the concentration of dust in the fluid is determined by analyzing the scattered light. In related technologies, the outer casing of the particulate matter concentration detection module is prone to static electricity, attracting surrounding dust. Dust can enter the airflow channel through gaps in the casing, affecting the detection results of the particulate matter concentration detection module. Utility Model Content

[0003] The purpose of this invention is to provide a particulate matter concentration detection module to solve the above-mentioned technical problems.

[0004] The particulate matter concentration detection module proposed in this utility model includes a housing, a detection element, a fan, and a circuit board. The housing includes a main body, an upper cover, and a lower cover. The first side of the main body is provided with an airflow channel and a beam channel, which intersect. The lower cover is located on the first side of the main body, and a dustproof sealing film is provided on the inner side of the lower cover. The dustproof sealing film is squeezed between the first side of the main body and the lower cover. The upper cover is located on the second side of the main body and is provided with an air inlet and an exhaust outlet. The detection element includes a light emitter and a light receiver. The light emitter emits a light beam along the beam channel, and the light receiver is located at the intersection of the airflow channel and the beam channel. The fan is located inside the housing and is used to introduce external airflow into the airflow channel through the air inlet and to discharge the airflow into the airflow channel through the exhaust outlet. The circuit board is located in the housing, and the detection element and / or the fan are electrically connected to the circuit board.

[0005] According to one embodiment of the present invention, the main body is provided with a first through hole, a second through hole and a third through hole, and the dustproof sealing film is provided with clearance positions corresponding to the first through hole, the second through hole and the third through hole. The clearance positions allow the inner surface of the lower cover to be exposed. The circuit board is provided with copper leakage areas corresponding to the first through hole and the third through hole. Springs are installed in the first through hole, the second through hole and the third through hole. The two ends of the springs in the first through hole and the third through hole respectively abut against the copper leakage area and the clearance position. The two ends of the springs in the second through hole respectively abut against the lower surface of the upper cover and the clearance position of the corresponding area of ​​the lower cover.

[0006] According to one embodiment of the present invention, the housing is further provided with a light trap structure. The light beam emitted by the light emitter is emitted along the beam channel and enters the light trap structure after passing through the intersection of the airflow channel and the beam channel.

[0007] According to one embodiment of the present invention, the light trap structure is formed by a light-blocking plate, an extension plate and a reflector. The light-blocking plate is located downstream of the intersection of the beam channel and the airflow channel and has a light-transmitting hole. The extension plate extends from one side of the light-blocking plate along the propagation direction of the beam to the edge of the main body and has an extinction structure. The reflector and the light-blocking plate form an angle of less than 90°.

[0008] According to one embodiment of the present invention, the matting structure is a serrated structure provided on the extension plate.

[0009] According to one embodiment of the present invention, a detection bracket is provided inside the housing, a beam channel is provided on the detection bracket, the emitting end of the light emitter faces the entrance of the beam channel, a clearance groove is provided on the detection bracket, the clearance groove forms the intersection of the airflow channel and the beam channel, a clearance hole is provided on the bottom surface of the clearance groove, and a light receiver is provided on the circuit board and aligned with the clearance hole.

[0010] According to one embodiment of the present invention, a light-blocking plate and an extension plate are disposed on a detection bracket. Along the direction of light transmission, the light-blocking plate is located downstream of the clearance groove, and the reflector is disposed on the housing.

[0011] According to one embodiment of the present invention, the main body is provided with a mounting position for accommodating the detection bracket. The shape of the mounting position is adapted to the detection bracket, and the detection bracket is disposed on the circuit board and placed in the mounting position.

[0012] According to one embodiment of the present invention, the airflow channel includes a first channel and a second channel. The first channel is disposed on the same side as the beam channel, and the second channel is located on the side of the circuit board away from the first channel. The first channel and the beam channel intersect and then communicate with the second channel.

[0013] According to one embodiment of the present invention, the first channel is located on one side of the mounting position, and a groove is provided on the other side of the mounting position. The part of the circuit board corresponding to the groove is provided with an air passage hole. The airflow in the first channel enters the groove after passing through the intersection of the first channel and the beam channel, and then enters the second channel through the air passage hole.

[0014] Compared with the prior art, the particulate matter concentration detection module of this utility model has the following advantages:

[0015] The particulate matter concentration detection module of this utility model has a dustproof sealing film between the lower cover and the main body, which can improve the sealing between the lower cover and the main body and prevent dust around the lower cover from entering the airflow channel through the gap between the lower cover and the main body. This avoids the dust from entering the intersection of the airflow channel and the beam channel and affecting the detection results of the particulate matter concentration detection module, thereby improving the detection accuracy of the particulate matter concentration detection module. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the particulate matter concentration detection module of this utility model;

[0017] Figure 2 This is a schematic diagram of the particulate matter concentration detection module of this utility model from another direction;

[0018] Figure 3 This is an exploded view of the particulate matter concentration detection module of this utility model;

[0019] Figure 4 This is a schematic diagram of the internal structure of the particulate matter concentration detection module of this utility model;

[0020] Figure 5 This is a schematic diagram of the internal structure of another embodiment of the particulate matter concentration detection module of this utility model;

[0021] Figure 6 This is a schematic diagram of the internal structure of another embodiment of the particulate matter concentration detection module of this utility model;

[0022] Figure 7 This is a schematic diagram of the detection bracket in this utility model.

[0023] In the diagram: a. Airflow channel, b. Beam channel, c. Light trap structure, 1. Housing, 11. Main body, 111. First through hole, 112. Second through hole, 113. Third through hole, 114. Reflector, 115. Mounting position, 116. Slot, 12. Top cover, 121. Air inlet, 122. Exhaust outlet, 13. Bottom cover, 131. Dustproof sealing film, 2. Detection element, 21. Light emitter, 22. Light receiver, 3. Fan, 4. Circuit board, 41. Vent hole, 5. Detection bracket, 51. Light blocking plate, 511. Light transmission hole, 52. Extension plate, 521. Extinction structure, 53. Clearance groove, 531. Clearance hole.

[0024] The implementation and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The following drawings will disclose several embodiments of this utility model. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit this utility model. That is, in some embodiments of this utility model, these practical details are not essential. In addition, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0026] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0027] Furthermore, in this utility model, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the utility model. They are merely used to distinguish components or operations described with the same technical terms and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0028] To further understand the content, features, and effects of this utility model, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0029] This utility model discloses a particulate matter concentration detection module. Please refer to [link / reference]. Figures 1 to 4The particulate matter concentration detection module proposed in this utility model includes a housing 1, a detection element 2, a fan 3, and a circuit board 4. The housing 1 includes a main body 11, an upper cover 12, and a lower cover 13. The first side of the main body 11 is provided with an airflow channel a and a beam channel b, which intersect. The lower cover 13 is placed on the first side of the main body 11, and a dustproof sealing film 131 is provided on the inner side of the lower cover 13. The dustproof sealing film 131 is pressed between the first side of the main body 11 and the lower cover 13. The upper cover 12 is placed on the first side of the main body 11. On both sides, an air inlet 121 and an exhaust outlet 122 are provided; the detection element 2 includes a light emitter 21 and a light receiver 22. The light emitter 21 emits a light beam along the beam channel b, and the light receiver 22 is located at the intersection of the airflow channel a and the beam channel b; the fan 3 is located inside the housing 1 and is used to introduce external airflow into the airflow channel a through the air inlet 121 and to discharge the airflow into the airflow channel a through the exhaust outlet 122; the circuit board 4 is located in the housing 1, and the detection element 2 and / or the fan 3 are electrically connected to the circuit board 4.

[0030] In this embodiment, the upper cover 12 and the lower cover 13 are opposite each other along the thickness direction of the main body 11. The circuit board 4 is disposed between the upper cover 12 and the lower cover 13. The air inlet 121 and the exhaust outlet 122 are both opened on the upper cover 12. Thus, when the particulate matter concentration detection module is installed in the application device, it is only necessary to keep the parts of the upper cover 12 where the air inlet 121 and the exhaust outlet 122 are not blocked. There is no need to expose the main body 11 and the lower cover 13, thereby simplifying the installation method of the particulate matter concentration detection module.

[0031] The air inlet 121 allows the measured airflow to enter the airflow channel a, and the exhaust port 122 allows the measured airflow to exit the airflow channel a. The fan 3 drives the airflow to enter the airflow channel a through the air inlet 121, flow along the airflow channel a, and then exit through the exhaust port 122. The circuit board 4 provides power to the fan 3 and the detection element 2 and distributes electrical signals.

[0032] The light emitter 21 emits a laser beam along the beam channel b. Since the beam channel b intersects with the air intake channel a, the laser beam enters the air intake channel a along the beam channel b. The beam entering the air intake channel a irradiates the fluid being measured flowing through the intersection of the air intake channel a and the beam channel b, generating scattered light. Part of the scattered light is received by the light receiver 22 installed at the intersection of the air intake channel a and the beam channel b. The light receiver 22 converts the received scattered light into an electrical signal. The signal adjustment circuit on the circuit board 4 amplifies the signal, performs noise reduction, and then sends the detection result to the processing unit. The processing unit calculates the dust concentration in the fluid being measured based on the processed detection signal.

[0033] The dustproof sealing film 131 is disposed between the lower cover 13 and the main body 11, which can improve the sealing between the lower cover 13 and the main body 11, prevent dust around the lower cover 13 from entering the airflow channel a through the gap between the lower cover 13 and the main body 11, and thus prevent this part of the dust from entering the intersection of the airflow channel a and the beam channel b and affecting the detection results of the particulate matter concentration detection module, thereby improving the detection accuracy of the particulate matter concentration detection module.

[0034] The particulate matter concentration detection module of this utility model, such as Figures 1 to 3 As shown, the main body 11 is provided with a first through hole 111, a second through hole 112 and a third through hole 113. The dustproof sealing film 131 is provided with clearance positions corresponding to the first through hole 111, the second through hole 112 and the third through hole 113. The clearance positions allow the inner surface of the lower cover 13 to be exposed. The circuit board 4 is provided with copper leakage areas corresponding to the first through hole 111 and the third through hole 113. Springs are installed in the first through hole 111, the second through hole 112 and the third through hole 113. The two ends of the springs in the first through hole 111 and the third through hole 113 respectively abut against the copper leakage area and the clearance position. The two ends of the springs in the second through hole 112 abut against the lower surface of the upper cover 12 and the clearance position of the corresponding area of ​​the lower cover 13 respectively.

[0035] The springs in the first through hole 111 and the third through hole 113 pass through the dustproof sealing film 131 and abut against the lower cover 13, while the other end abuts against the exposed copper area of ​​the circuit board 4, thus enabling the lower cover 13 to conduct electricity with the circuit board 4. The spring in the second through hole 112 passes through the dustproof sealing film 131 and abuts against the lower cover 13, while the other end abuts against the upper cover 12, thus enabling the lower cover 13 to conduct electricity with the upper cover 12. When the particulate matter concentration detection module is installed, the lower cover 13 is in contact with the installation environment, meaning the lower cover 13 is grounded. The exposed copper area of ​​the circuit board 4 and the upper cover 12 are both connected to the lower cover 13, allowing both the exposed copper area of ​​the circuit board 4 and the upper cover 12 to be grounded through the lower cover 13. This means that the static electricity of the exposed copper area and the upper cover 12 can be discharged to the installation environment through the lower cover 13, thereby grounding the entire housing 1 and preventing the housing 1 from becoming charged. This prevents the housing 1 from attracting surrounding dust due to being charged, thus reducing the possibility that the attracted dust will enter the airflow channel a and affect the detection results. In addition, the housing 1 is not charged after being grounded, which can prevent the charge from affecting the signal transmission and reception of the signal devices on the circuit board 4, thus playing a role in resisting signal interference.

[0036] The particulate matter concentration detection module of this utility model, such as Figures 4 to 7 As shown, the housing 1 is also provided with a light trap structure c. The light beam emitted by the light emitter 21 is emitted along the beam channel b and enters the light trap structure c after passing through the intersection of the airflow channel a and the beam channel b.

[0037] The light trap structure c is used to reduce the reflected light generated when the light beam emitted by the light emitter 21 passes through the avoidance groove and shines on the side wall of the housing 1, which then enters the avoidance groove again and generates new scattered light that is received by the light receiver 22, thus affecting the detection results.

[0038] When the light beam emitted by the light emitter 21 enters the light trap structure c through the light-transmitting hole, it will illuminate the side wall of the light trap structure c and be reflected. The emitted light will be blocked by the light-blocking plate 51 and will be difficult to penetrate the relief groove, thereby avoiding the generation of new scattered light that will be received by the light receiver 22 and affect the detection results.

[0039] The particulate matter concentration detection module of this utility model, such as Figures 5 to 6 As shown, the light trap structure c is surrounded by a light-blocking plate 51, an extension plate 52, and a reflector 114. The light-blocking plate 51 is located downstream of the intersection of the beam channel b and the airflow channel a, and has a light-transmitting hole 511 on it. The extension plate 52 extends from one side of the light-blocking plate 51 along the propagation direction of the beam to the edge of the main body 11. The extension plate 52 has an extinction structure 521 on it. The reflector 114 forms an angle of less than 90° with the light-blocking plate 51.

[0040] The light-blocking plate 51, reflector 114, and extension plate 52 form a triangular light trap structure c. The surface of the reflector 114 forms an acute angle with the surface of the light-blocking plate 51. The light beam entering the light trap structure c first hits the reflector 114, which reflects most of the light onto the extinction structure 521 of the extension plate 52. The extinction structure 521 includes at least one protrusion, which can reflect the reflected light generated on the extinction structure 521 again. Through multiple reflections, most of the reflected light can be canceled out. Very little reflected light re-enters the clearance groove through the light-transmitting hole 511, thus reducing interference from light on the detection results and improving the accuracy of the detection results.

[0041] The particulate matter concentration detection module of this utility model, such as Figures 5 to 7 As shown, the extinction structure 521 is a serrated structure disposed on the extension plate 52. The extinction structure 521 may be composed of multiple continuously arranged protrusions, the protrusions being triangular, so that the combined extinction structure 521 is serrated. The serrated extinction structure 521 can improve the extinction effect after light irradiation, canceling out more reflected light, thereby further reducing the interference of interfering light on the detection results and further improving the accuracy of the detection results.

[0042] The particulate matter concentration detection module of this utility model, such as Figure 7As shown, a detection bracket 5 is provided inside the housing 1, and a beam channel b is provided on the detection bracket 5. The emitting end of the light emitter 21 faces the entrance of the beam channel b. A clearance groove 53 is provided on the detection bracket 5. The clearance groove 53 forms the intersection of the airflow channel a and the beam channel b. A clearance hole 531 is provided on the bottom surface of the clearance groove 53. The light receiver 22 is provided on the circuit board 4 and is aligned with the clearance hole 531.

[0043] The detection bracket 5 forms a beam channel b. A light emitter 21 is installed at the entrance of beam channel b. The light beam emitted by the light emitter 21 can enter the clearance groove 53 along beam channel b. The clearance groove 53 forms a partial air intake channel a, which is located on the flow path of the measured airflow. As the measured airflow flows from the air inlet 121 to the exhaust channel, it passes through the clearance groove 53. Therefore, the light beam entering the clearance groove 53 will irradiate the measured airflow flowing through the clearance groove 53, generating scattered light. Some of the scattered light will enter the clearance hole 531 and is finally received by the light receiver 22, which is aligned with the clearance hole 531. The detection bracket 5 ensures that the light beam emitted by the light emitter 21 can stably enter the clearance groove 53, that is, the intersection of the air intake channel a and the beam channel b, thus ensuring that the light beam can irradiate the measured airflow flowing through the clearance groove 53.

[0044] The particulate matter concentration detection module of this utility model, such as Figures 5 to 6 As shown, the light-blocking plate 51 and the extension plate 52 are disposed on the detection bracket 5. Along the light transmission direction, the light-blocking plate 51 is located downstream of the clearance groove 53, and the reflector 114 is disposed on the housing 1.

[0045] The reflector 114 of the light trap structure c is formed by the inner wall of the housing 1 instead of the detection bracket 5. This simplifies the shape of the detection bracket 5 and increases the distance between the reflector 114 and the light-transmitting hole 511, making it more difficult for the light reflected by the reflector 114 to reach the light-transmitting hole 511. This further reduces the interference of interfering light on the detection results and further improves the accuracy of the detection results.

[0046] The particulate matter concentration detection module of this utility model, such as Figure 3 As shown, the main body 11 is provided with a mounting position 115 for accommodating the detection bracket 5. The shape of the mounting position 115 is adapted to the detection bracket 5. The detection bracket 5 is located on the circuit board 4 and is placed in the mounting position 115.

[0047] The testing bracket 5 can be adapted and installed within the mounting position 115, thereby improving the installation stability of the testing bracket 5 within the housing 1, reducing the idle space within the housing 1, and improving the effective utilization rate of the space within the housing 1. The testing bracket 5 is connected to the circuit board 4, which can provide support for the circuit board 4, and the circuit board 4 can also provide positioning for the testing bracket 5.

[0048] The particulate matter concentration detection module of this utility model, such as Figures 2 to 3 As shown, the airflow channel a includes a first channel and a second channel. The first channel is located on the same side as the beam channel b, and the second channel is located on the side of the circuit board 4 away from the first channel. The first channel and the beam channel b intersect and then connect with the second channel.

[0049] The first channel is connected to the air inlet 121, and the second channel is connected to the exhaust outlet 122. The airflow to be measured flows into the air inlet channel a from the air inlet 121, then flows through the exhaust channel, and finally flows out of the exhaust outlet 122. The first channel and the second channel are located on both sides of the circuit board 4.

[0050] The particulate matter concentration detection module of this utility model, such as Figure 6 As shown, the first channel is located on one side of the mounting position 115, and the other side of the mounting position 115 is provided with a recess 116. The part of the circuit board 4 corresponding to the recess 116 is provided with an air passage 41. The airflow in the first channel enters the recess 116 after passing through the intersection of the first channel and the beam channel b, and then enters the second channel through the air passage 41.

[0051] The air passage 41 connects the first channel and the second channel. The airflow that flows into the first channel from the air inlet 121 flows through the detection bracket 5 installed at the mounting position 115 and then flows into the second channel located on the other side of the circuit board 4 through the air passage 41 at the sink 116. The sink 116 can ensure that the airflow has a certain buffer space before flowing into the air passage 41, preventing the airflow from becoming turbulent at the air passage 41.

[0052] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A particulate matter concentration detection module, characterized in that, include: The housing (1) includes a main body (11), an upper cover (12) and a lower cover (13). The first side of the main body (11) is provided with an airflow channel (a) and a beam channel (b), which intersect. The lower cover (13) is placed on the first side of the main body (11), and a dustproof sealing film (131) is provided on the inner side of the lower cover (13). The dustproof sealing film (131) is squeezed between the first side of the main body (11) and the lower cover (13). The upper cover (12) is placed on the second side of the main body (11), and an air inlet (121) and an exhaust outlet (122) are provided thereon. The detection element (2) includes a light emitter (21) and a light receiver (22), wherein the light emitter (21) emits a light beam along the beam channel (b), and the light receiver (22) is located at the intersection of the airflow channel (a) and the beam channel (b); A fan (3) is disposed inside the housing (1) for introducing external airflow into the airflow channel (a) through the air inlet (121) and discharging the airflow that has entered the airflow channel (a) through the exhaust port (122); A circuit board (4) is disposed in the housing (1), and the detection element (2) and / or fan (3) are electrically connected to the circuit board (4).

2. The particulate matter concentration detection module according to claim 1, characterized in that, The main body (11) is provided with a first through hole (111), a second through hole (112), and a third through hole (113). The dustproof sealing film (131) is provided with clearance positions (1311) corresponding to the first through hole (111), the second through hole (112), and the third through hole (113). The clearance positions (1311) allow the inner surface of the lower cover (13) to be exposed. The circuit board (4) is provided with clearance positions corresponding to the first through hole (111) and the third through hole (113). 3) In the corresponding copper leakage area, springs are installed in the first through hole (111), the second through hole (112) and the third through hole (113). The two ends of the springs in the first through hole (111) and the third through hole (113) respectively abut against the copper leakage area and the clearance position (1311). The two ends of the spring in the second through hole (112) abut against the lower surface of the upper cover (12) and the clearance position (1311) of the corresponding area of ​​the lower cover (13) respectively.

3. The particulate matter concentration detection module according to claim 1, characterized in that, The housing (1) is also provided with a light trap structure (c). The light beam emitted by the light emitter (21) is emitted along the light beam channel (b) and enters the light trap structure (c) after passing through the intersection of the airflow channel (a) and the light beam channel (b).

4. The particulate matter concentration detection module according to claim 3, characterized in that, The light trap structure (c) is surrounded by a light-blocking plate (51), an extension plate (52), and a reflector (114). The light-blocking plate (51) is located downstream of the intersection of the beam channel (b) and the airflow channel (a), and has a light-transmitting hole (511). The extension plate (52) is formed by extending from one side of the light-blocking plate (51) along the propagation direction of the beam to the edge of the main body (11). The extension plate (52) has an extinction structure (521). The reflector (114) forms an angle of less than 90° with the light-blocking plate (51).

5. The particulate matter concentration detection module according to claim 4, characterized in that, The matting structure (521) is a serrated structure provided on the extension plate (52).

6. The particulate matter concentration detection module according to claim 4, characterized in that, The housing (1) is provided with a detection bracket (5), the beam channel (b) is provided on the detection bracket (5), the emitting end of the light emitter (21) faces the entrance of the beam channel (b), the detection bracket (5) is provided with a clearance groove (53), the clearance groove (53) forms the intersection of the airflow channel (a) and the beam channel (b), the bottom surface of the clearance groove (53) is provided with a clearance hole (531), and the light receiver (22) is provided on the circuit board (4) and aligned with the clearance hole (531).

7. The particulate matter concentration detection module according to claim 6, characterized in that, The light-blocking plate (51) and the extension plate (52) are disposed on the detection bracket (5). Along the light transmission direction, the light-blocking plate (51) is located downstream of the clearance groove (53), and the reflector (114) is disposed on the housing (1).

8. The particulate matter concentration detection module according to claim 6, characterized in that, The main body (11) is provided with a mounting position (115) for accommodating the detection bracket (5). The shape of the mounting position (115) is adapted to the detection bracket (5). The detection bracket (5) is located on the circuit board (4) and is placed in the mounting position (115).

9. The particulate matter concentration detection module according to claim 8, characterized in that, The airflow channel (a) includes a first channel and a second channel. The first channel is located on the same side as the beam channel (b), and the second channel is located on the side of the circuit board (4) away from the first channel. The first channel and the beam channel (b) intersect and then communicate with the second channel.

10. The particulate matter concentration detection module according to claim 9, characterized in that, The first channel is located on one side of the mounting position (115), and the other side of the mounting position (115) is provided with a recess (116). The part of the circuit board (4) corresponding to the recess (116) is provided with an air passage (41). The airflow in the first channel enters the recess (116) after passing through its intersection with the beam channel (b), and then enters the second channel through the air passage (41).

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