An air path system for a particle counting sensor

Abstract

The utility model provides a kind of gas path system of particle counting sensor, and sensor shell is combined and installed, the sensor shell inside has the cavity for light beam and the light-sensitive area formed by the overlapping of to-be-measured airflow, the gas path system of particle counting sensor includes the air inlet pipe and exhaust pipe combined and installed with the sensor shell, the air inlet pipe and the exhaust pipe all pass through the sensor shell and stretch into the cavity inside, and the air inlet pipe and the exhaust pipe are located at the opposite sides of light-sensitive area, and the air inlet pipe and the exhaust pipe are coaxially arranged;The air inlet pipe has gas outlet in one end in the cavity, and the exhaust pipe has air inlet in one end in the cavity, and the cross-sectional projection of the air inlet along the exhaust pipe axial direction is greater than and covers the cross-sectional projection of the gas outlet along the exhaust pipe axial direction.The gas path system of particle counting sensor can effectively reduce the settling amount of particulate matter in to-be-measured airflow in the cavity.

Description

Technical Field

[0001] This utility model relates to the field of environmental monitoring technology, and more precisely to a gas path system for a particle counting sensor. Background Technology

[0002] A particle counting sensor is a device used to detect the size and number of particles in an environment. A particle counting sensor typically consists of a light source, an optical module, a gas path module, and a photodetector. The light beam emitted by the light source is shaped by the optical module to form a collimated beam. The gas path module delivers the airflow to be detected. The beam illuminates the overlapping area of ​​the airflow, forming a photosensitive region. Particles in the airflow emit scattered light after being illuminated. This scattered light is received by a photodetector located on one side of the photosensitive region and converted into a photocurrent. The photocurrent is then amplified and processed by a circuit to convert it into a voltage pulse signal. By comparing different voltage pulse signals, the particle size can be determined. Particle counting sensors are high-precision testing instruments; factors such as particle velocity, airflow pressure, temperature, and internal particle deposition all affect their measurement accuracy.

[0003] Prolonged operation of particle counting sensors in high-concentration particle environments can lead to particle deposition within the sensor's internal cavities, affecting the counting accuracy and, in severe cases, rendering the sensor unable to count. For example, particle deposition on the inner walls of cavities can impair stray light absorption; deposition in mirrors can prevent them from effectively collecting scattered light and projecting it onto the photodetector; and deposition on the photodetector can prevent the photodetector from acquiring the scattered particle light, thus affecting the generation of voltage pulse signals.

[0004] To address the issue of particle deposition in particle counting sensors under high-concentration particulate environments, existing technologies generally employ a sheath gas protection structure in the air inlet pipe. This sheath gas protection structure needs to output sheath gas to envelop the measured airflow, preventing particle deposition. However, the sheath gas output by this structure not only needs to fully envelop the measured airflow but also must avoid affecting its flow. This requires high adjustment precision and involves a relatively complex structure, resulting in limited effectiveness in preventing deposition in highly polluted environments.

[0005] In summary, there is a need in this field for a technical solution that can effectively avoid particle deposition inside particle counting sensors and has a simpler mechanism. Utility Model Content

[0006] In view of this, the purpose of this utility model is to provide a gas path system for a particle counting sensor, which prevents internal particle deposition by improving the gas path structure.

[0007] To achieve the above objectives, this utility model provides a gas path system for a particle counting sensor, which is installed in conjunction with a sensor housing. The sensor housing has a cavity inside for the light beam and the gas flow to be measured to overlap and form a photosensitive area. The gas path system of the particle counting sensor includes an inlet pipe and an exhaust pipe installed in conjunction with the sensor housing. Both the inlet pipe and the exhaust pipe extend through the sensor housing into the cavity, and are located on opposite sides of the photosensitive area. The inlet pipe and the exhaust pipe are coaxially arranged. The end of the inlet pipe located in the cavity has an outlet, and the end of the exhaust pipe located in the cavity has an inlet. The cross-sectional projection of the inlet along the axis of the exhaust pipe is greater than and covers the cross-sectional projection of the outlet along the axis of the exhaust pipe.

[0008] Preferably, the distance between the air outlet and the air inlet is 3-20mm.

[0009] Preferably, along the air intake direction, the air intake passage in the air intake pipe includes a first air intake passage and a second air intake passage arranged in sequence and connected to each other, wherein the cross-sectional area of ​​the second air intake passage is smaller than the cross-sectional area of ​​the first air intake passage.

[0010] Preferably, the first air intake channel and the second air intake channel are gradually connected by a transition channel, which is a tapered channel.

[0011] Preferably, the second air intake channel is a straight circular channel, or the end of the second air intake channel near the exhaust pipe is a flat opening.

[0012] Preferably, the first direction is the propagation direction of the light beam on the optical axis within the cavity, and the maximum length of the air outlet along the first direction is less than the length of the air inlet along the first direction; the second direction is the direction perpendicular to the first direction and the axis of the air inlet pipe, and the maximum width of the air outlet along the second direction is less than the width of the air inlet along the second direction.

[0013] Preferably, the exhaust pipe has an exhaust channel with a uniform inner diameter.

[0014] Preferably, the diameter of the exhaust channel is 1.2-3 times the maximum length of the air outlet along the first direction, and the maximum length of the air outlet along the first direction is 1-3 times the maximum width of the air outlet along the second direction.

[0015] Preferably, the sensor housing has a stepped hole for inserting the air intake pipe and the exhaust pipe, and an elastic sealing ring is provided at the bottom of the stepped hole. The air intake pipe and the exhaust pipe are respectively fixedly connected to the sensor housing through external baffles.

[0016] Compared with the prior art, the advantages of the air path system of the particle counting sensor disclosed in this utility model are: the air path system of the particle counting sensor improves the air path structure so that the airflow to be measured is transmitted from the outlet of the inlet pipe to the inlet of the exhaust pipe faster and more completely, effectively reducing the amount of particulate matter in the airflow to be measured settling in the cavity. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] like Figure 1 The image shown is a cross-sectional view of the gas path system of a particle counting sensor according to this application.

[0019] like Figure 2 The image shown is a cross-sectional view of the combined gas path system and optical path system of a particle counting sensor according to this application. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1 and Figure 2As shown, this application discloses a gas path system for a particle counting sensor. The gas path system is installed in conjunction with a sensor housing 1. The sensor housing 1 has a cavity 10 inside which a light beam 51 overlaps with the gas flow 6 to be measured to form a photosensitive area 4. The gas path system of the particle counting sensor includes an inlet pipe 2 and an exhaust pipe 3 installed in conjunction with the sensor housing 1. Both the inlet pipe 2 and the exhaust pipe 3 extend through the sensor housing 1 into the cavity 10, and are located on opposite sides of the photosensitive area. The inlet pipe 2 and the exhaust pipe 3 are coaxially arranged. The gas to be measured enters the cavity 10 through the inlet pipe 2 and is discharged through the exhaust pipe 3. The end of the inlet pipe 2 located in the cavity 10 has an outlet 25, and the end of the exhaust pipe 3 located in the cavity 10 has an inlet 32. The cross-sectional projection of the inlet 32 ​​along the axis of the exhaust pipe 3 is larger than and covers the cross-sectional projection of the outlet 25 along the axis of the exhaust pipe 3. The gas to be tested discharged from the air inlet pipe 2 through the air outlet 25 can enter the exhaust pipe 3 through the air inlet 32 ​​without obstruction, thereby reducing the amount of particles in the gas to be tested deposited in the cavity 10.

[0022] A particle counting sensor typically includes an optical system, a gas system, and a scattered light collection and receiving system. In the optical system, a light source 5, such as a laser, emits a light beam 51, which is collimated and compressed by an optical shaping module and then intersects with the gas to be measured 6 transmitted in the gas system in the cavity 10 of the housing to form a photosensitive area. After passing through the photosensitive area, the light beam propagates to the light trap 7 and is then removed by the light trap 7.

[0023] In some embodiments, the propagation direction of the light beam on the optical axis within the cavity 10 is taken as the first direction X, and the maximum length of the outlet 25 along the first direction is less than the length of the inlet 32 ​​along the first direction; the direction perpendicular to the first direction and the axis of the inlet pipe is taken as the second direction, and the maximum width of the outlet 25 along the second direction is less than the width of the inlet 32 ​​along the second direction. The outlet 25 can be of various shapes, such as a round or flat opening, preferably a flat ellipse or a flat rectangle, etc., and the maximum length of the outlet 25 along the first direction is greater than the maximum width of the outlet 25 along the second direction. The flat outlet discharges a more concentrated and faster flow of the gas to be tested, and the residence time of a single particle inside the cavity 10 is shorter, further reducing the amount of particles deposited in the cavity 10.

[0024] The intake pipe 2 and the exhaust pipe 3 are coaxially arranged to ensure that the exhaust port 25 is aligned with the center of the intake port 32, further reducing the amount of particles deposited in the cavity 10.

[0025] In some embodiments, the distance between the air outlet 25 and the air inlet 32 ​​is as close as possible without disturbing the propagation of the light beam in the cavity, preferably 3-20 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 12 mm, 15 mm, 18 mm, etc., and more preferably 4-10 mm. By shortening the distance between the air outlet 25 and the air inlet 32, the residence time of a single particle inside the cavity 10 can be further reduced, and the amount of particle deposition in the cavity 10 can be further reduced.

[0026] In some embodiments, the intake pipe 2 has an intake channel 20 inside. Along the intake direction Y, the intake channel 20 includes a first intake channel 21 and a second intake channel 22 arranged sequentially and connected. The cross-sectional area of ​​the second intake channel 22 is smaller than that of the first intake channel 21. Alternatively, the second intake channel 22 can be a straight circular channel; or the end of the second intake channel 22 near the exhaust pipe 3 can be a flat opening, i.e., a flat-mouth opening. When the end near the exhaust pipe 3 is flat, the outlet has a flat shape. Alternatively, the first intake channel 21 and the second intake channel 22 can be gradually connected by a transition channel 23, which is a conical channel. The intake channel 20 can accelerate the gas to be tested, increasing the speed at which the gas passes through the inner cavity 10 and reducing the amount of particles deposited in the cavity 10.

[0027] In some embodiments, the exhaust pipe 3 has an exhaust channel 30 with a uniform inner diameter, which helps the gas to be discharged quickly.

[0028] In some embodiments, the diameter of the exhaust channel 30 is preferably 1.2-3 times the maximum length of the outlet 25 along the first direction, for example, 1.3, 1.8, 2.1, 2.5 times, etc.; the maximum length of the outlet 25 along the first direction is 1-3 times the maximum width of the outlet 25 along the second direction, for example, 1, 1.5, 2 times, etc., to ensure that the gas to be tested is completely discharged. For example, the outlet is a flat opening, the diameter of the exhaust channel 30 is twice the maximum length of the outlet 25 along the first direction, and the maximum length of the outlet 25 along the first direction is twice the maximum width of the outlet 25 along the second direction. For example, when the second intake channel 22 is a uniformly straight circular channel, the outlet is a circular opening, the diameter of the exhaust channel 30 is 1.8 times the maximum length of the outlet 25 along the first direction, and the maximum length of the outlet 25 along the first direction is once the maximum width of the outlet 25 along the second direction. For example, the diameter of the exhaust channel 30 can be set to 6-12mm, such as 6.5mm, 7.0mm, 8.0mm, 9.0mm, etc., without any specific limitation.

[0029] In some embodiments, the sensor housing 1 has a stepped hole for inserting an air inlet pipe 2 and an exhaust pipe 3, and an elastic sealing ring is provided at the bottom of the stepped hole. The air inlet pipe 2 and the exhaust pipe 3 are respectively fixedly connected to the sensor housing 1 through an external baffle.

[0030] Specifically, the sensor housing 1 has a first stepped hole 11 at the position where the air inlet pipe 2 is inserted. The side of the air inlet pipe 2 has a first baffle 24, and the first baffle 24 has a first stepped portion corresponding to the first stepped hole 11. The air inlet pipe 2 is inserted into the first stepped hole 11 through the first stepped portion, and the first baffle 24 is fixedly connected to the sensor housing 1 by bolts. Furthermore, a first elastic sealing ring 111 is provided at the bottom of the first stepped hole 11 to prevent external particles from entering the cavity 10 through the connection.

[0031] The sensor housing 1 has a second stepped hole 12 at the position where the exhaust pipe 3 is inserted. The side of the exhaust pipe 3 has a second baffle 31, and the second baffle 31 has a second stepped portion corresponding to the second stepped hole 12. The exhaust pipe 3 is inserted into the second stepped hole 12 through the second stepped portion, and the second baffle 31 is fixedly connected to the sensor housing 1 by bolts. Furthermore, a second elastic sealing ring 121 is provided at the bottom of the second stepped hole 12 to prevent external particles from entering the cavity 10 through the connection.

[0032] In a preferred embodiment, the intake pipe 2 and the exhaust pipe 3 are coaxially arranged to ensure that the exhaust port 25 is aligned with the center of the intake port 32, further reducing the amount of particles deposited in the cavity 10. The distance between the exhaust port 25 and the intake port 32 is 4-10 mm. By shortening the distance between the exhaust port 25 and the intake port 32, the residence time of a single particle inside the cavity 10 can be further reduced, further reducing the amount of particles deposited in the cavity 10. The cross-sectional area of ​​the second intake channel 22 is smaller than that of the first intake channel 21. The area of ​​the second intake channel 22 is as follows: it is a straight circular channel; or the end of the second intake channel 22 near the exhaust pipe 3 is a flat opening, i.e., a flat-mouth opening. The first intake channel 21 and the second intake channel 22 are gradually connected by a transition channel 23, which is a conical channel. The intake channel 20 can accelerate the gas to be tested, increase the speed of the gas to be tested passing through the inner cavity 10, and reduce the amount of particles deposited in the cavity 10. The exhaust pipe 3 has a straight exhaust channel 30 with a uniform inner diameter, which helps the gas to be tested to be discharged quickly. The diameter of the exhaust channel 30 is 1.2-3 times the maximum length of the outlet 25 along the first direction, and the maximum length of the outlet 25 along the first direction is 1-3 times the maximum width of the outlet 25 along the second direction, to ensure that the gas to be tested is completely discharged. The sensor housing 1 has a first stepped hole 11 at the position where the air inlet pipe 2 is inserted. The side of the air inlet pipe 2 has a first baffle 24, and the first baffle 24 has a first stepped portion corresponding to the first stepped hole 11. The air inlet pipe 2 is inserted into the first stepped hole 11 through the first stepped portion. The first baffle 24 is fixedly connected to the sensor housing 1 by bolts. Furthermore, a first elastic sealing ring 111 is provided at the bottom of the first stepped hole 11 to prevent external particles from entering the cavity 10 through the connection. The sensor housing 1 has a second stepped hole 12 at the position where the exhaust pipe 3 is inserted. The side of the exhaust pipe 3 has a second baffle 31, and the second baffle 31 has a second stepped portion corresponding to the second stepped hole 12. The exhaust pipe 3 is inserted into the second stepped hole 12 through the second stepped portion. The second baffle 31 is fixedly connected to the sensor housing 1 by bolts. Furthermore, a second elastic sealing ring 121 is provided at the bottom of the second stepped hole 12 to prevent external particles from entering the cavity 10 through the connection.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An air path system of a particle counting sensor, which is installed in combination with a sensor housing having a cavity inside for forming a light sensitive area by overlapping a light beam with an air flow to be measured, characterized in that, The gas path system of the particle counting sensor includes an inlet pipe and an exhaust pipe that are mounted together with the sensor housing. Both the inlet pipe and the exhaust pipe extend through the sensor housing into the cavity and are located on opposite sides of the photosensitive area. The inlet pipe and the exhaust pipe are coaxially arranged. The end of the inlet pipe located in the cavity has an outlet, and the end of the exhaust pipe located in the cavity has an inlet. The cross-sectional projection of the inlet along the axis of the exhaust pipe is greater than and covers the cross-sectional projection of the outlet along the axis of the exhaust pipe.

2. The air path system of the particle count sensor according to claim 1, wherein The distance between the air outlet and the air inlet is 3-20mm.

3. The air path system of the particle count sensor according to claim 1, wherein Along the air intake direction, the air intake pipe includes a first air intake channel and a second air intake channel arranged in sequence and connected to each other, wherein the cross-sectional area of ​​the second air intake channel is smaller than the cross-sectional area of ​​the first air intake channel.

4. The air path system of the particle count sensor according to claim 3, wherein The first air intake channel and the second air intake channel are gradually connected by a transition channel, which is a tapered channel.

5. The air path system of the particle counting sensor according to claim 3 or 4, wherein The second intake channel is a straight circular channel, or the end of the second intake channel near the exhaust pipe is a flat opening.

6. The air path system of the particle count sensor according to claim 1, wherein, The first direction is the propagation direction of the light beam on the optical axis within the cavity, and the maximum length of the air outlet along the first direction is less than the length of the air inlet along the first direction; the second direction is the direction perpendicular to the first direction and the axis of the air inlet pipe, and the maximum width of the air outlet along the second direction is less than the width of the air inlet along the second direction.

7. The air path system of the particle count sensor according to claim 6, wherein The exhaust pipe has a straight exhaust channel with a uniform inner diameter.

8. The air path system of the particle count sensor according to claim 7, wherein The diameter of the exhaust channel is 1.2-3 times the maximum length of the exhaust port along the first direction, and the maximum length of the exhaust port along the first direction is 1-3 times the maximum width of the exhaust port along the second direction.

9. The gas path system of the particle counting sensor as described in claim 1, characterized in that, The sensor housing has a stepped hole for inserting the air intake pipe and the exhaust pipe, and an elastic sealing ring is provided at the bottom of the stepped hole. The air intake pipe and the exhaust pipe are respectively fixedly connected to the sensor housing through external baffles.

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