Dust particle counter and dust particle counting method

Abstract

The embodiment of the invention provides a dust particle counter and a dust particle counting method. The dust particle counter comprises a connecting pipe, and the connecting pipe comprises an air inlet section and a coating section; the air inlet section and the coating section are sequentially arranged in the airflow direction, and the inner diameters of the air inlet section and the coating section are sequentially decreased to form a stepped flow channel, or the coating section coats the air inlet section in the radial direction, and a clean airflow flow channel of the coating section coats the outer side of a to-be-detected airflow flow channel of the air inlet section; at least one first clean air inlet is formed in the side wall of the wrapping section, and the first clean air inlet is communicated with clean air flow; one end of the first air pipe is inserted into the air inlet section, and the other end is communicated with to-be-detected air flow; wherein the volume flow of the clean air flow is greater than that of the air flow to be measured. According to the dust particle counter provided by the embodiment of the invention, dust of the to-be-detected air flow is prevented from falling into the laser sensing cavity by designing a flowing mode that the to-be-detected air flow is wrapped by the clean air flow, so that light path pollution is reduced, and counting accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of dust particle detection technology, and in particular to a dust particle counter and a dust particle counting method. Background Technology

[0002] The dust particle counter uses the principle of laser scattering. The airflow to be measured enters the optical sensing cavity, and the airflow is irradiated by a laser beam, causing dust particles to generate scattering pulses for counting. In actual operation, some particles in the airflow containing dust particles will gradually deposit on the inner wall of the cavity, the laser window, and the sensor surface due to factors such as decreased flow velocity, turbulence, and electrostatic adsorption. This leads to optical path contamination, increased scattering substrate, and decreased signal-to-noise ratio, resulting in counting drift or even failure.

[0003] Currently, attempts are being made to reduce the amount of dust inside the cavity by adding simple filters at the cavity inlet or by regularly wiping and cleaning it manually. However, the filters are prone to clogging, have high pressure loss, and cannot prevent micron-sized particles from entering. Manual maintenance requires stopping and disassembling the machine, which reduces the efficiency of online detection and may introduce secondary pollution.

[0004] Therefore, there is an urgent need for a dustproof technology that can keep the cavity clean without interrupting detection, prevent dust accumulation, and be easy to maintain, so as to ensure the high accuracy and stability of dust particle counting in the long term. Summary of the Invention

[0005] This application provides a dust particle counter and a dust particle counting method to solve or alleviate one or more technical problems in the prior art.

[0006] As a first aspect of the embodiments of this application, the embodiments of this application provide a dust particle counter, including: Laser sensing cavity; The connecting pipe includes an air inlet section and a covering section; the air inlet section and the covering section are arranged sequentially along the airflow direction and their inner diameters decrease sequentially to form a stepped flow channel, or the covering section covers the air inlet section in the radial direction, and the clean airflow channel of the covering section covers the outside of the airflow channel to be measured of the air inlet section; the side wall of the covering section is provided with at least one first clean air inlet, and the first clean air inlet is connected to the clean airflow. The first trachea has one end inserted into the air intake section and the other end connected to at least the airflow to be measured. Multiple flow sensors are used to detect the flow rate of the clean airflow and the total flow rate of the clean airflow and the airflow to be measured; In this process, the volumetric flow rate of the clean airflow is greater than that of the airflow to be measured, causing the clean airflow to form an annular air curtain that completely envelops the airflow to be measured as it enters the laser sensing cavity.

[0007] In one embodiment, the connecting pipe further includes a guide section, an air inlet section, a covering section and a guide section arranged sequentially along the airflow direction, with the inner diameter decreasing sequentially to form a stepped flow channel; the first air pipe abuts against the first step between the air inlet section and the covering section.

[0008] In one embodiment, the inner surface of at least a portion of the arc of the first clean air inlet is inclined in a direction from the outside to the inside toward the guide section, with an inclination angle of 15°-70°.

[0009] In one embodiment, the first clean air inlet is cylindrical or conical. In the case of a conical inlet, the larger opening faces outward and the smaller opening faces inward.

[0010] In one embodiment, the inner diameter of the first trachea is smaller than the inner diameter of the covering section.

[0011] In one embodiment, the clean airflow channel is an annular channel or includes multiple channels, which are evenly distributed around the airflow channel to be tested.

[0012] In one embodiment, the connecting pipe includes an outlet located downstream of the coating section; the dust particle counter includes a first connecting pipe and a second connecting pipe; The first connecting pipe is an air inlet assembly, and its air outlet is connected to the air inlet of the laser sensing cavity. The first air pipe is connected to the gas source to be tested. The second connecting pipe is the gas outlet assembly, which discharges gas from the laser sensing cavity after the first gas pipe is connected to the detection.

[0013] In one embodiment, the clean airflow rate of the intake assembly is greater than the clean airflow rate of the exhaust assembly.

[0014] In one implementation, a controller is also included; The controller is electrically connected to the flow sensor and is used to adjust the clean airflow rate of the first clean air inlet and / or the second clean air inlet according to the measurement value of the flow sensor.

[0015] As a second aspect of the embodiments of this application, this application provides a dust particle counting method, applied to a dust particle counter in any of the above embodiments, including: A clean airflow is introduced from the first clean air inlet; After the preset duration, the airflow to be measured is introduced into the first trachea; Obtain the counting results; the flow rate of the air to be measured is the difference between the total flow rate and the flow rate of the clean air.

[0016] The dust particle counter provided in this application embodiment is designed to cover the flow of the air to be measured with clean airflow, thereby preventing dust from falling into the laser sensing cavity, thus reducing optical path contamination and improving counting accuracy.

[0017] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0018] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0019] Figure 1 A schematic diagram of the gas path structure of a dust particle counter according to an embodiment of this application is shown.

[0020] Figure 2 A schematic diagram of the structure of a connecting pipe according to an embodiment of this application is shown.

[0021] Figure 3 A cross-sectional structural schematic diagram of a connecting pipe according to an embodiment of this application is shown.

[0022] Figure 4 A schematic diagram of the connecting pipe according to another embodiment of this application is shown.

[0023] Figure 5 A cross-sectional structural schematic diagram of a connecting pipe according to another embodiment of this application is shown.

[0024] Figure 6 A schematic diagram of a connecting tube connected to a laser sensing cavity according to another embodiment of this application is shown.

[0025] Figure 7 A schematic flowchart of a dust particle counting method according to an embodiment of this application is shown. Detailed Implementation

[0026] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0027] This application provides a dust particle counter. Figure 1 A schematic diagram of the gas path structure of a dust particle counter according to an embodiment of this application is shown.

[0028] Example 1 Figure 2 A schematic diagram of the structure of a connecting pipe according to an embodiment of this application is shown. Figure 3 A cross-sectional structural schematic diagram of a connecting pipe according to an embodiment of this application is shown. Figures 1 to 3 As shown, the dust particle counter includes: a laser sensing cavity 100, a connecting tube 200, and a first air tube 300 (illustrated by a quick-connect connector in the connecting tube).

[0029] The laser sensing cavity 100 can be integrally machined from 316L stainless steel. For example, the inner cavity diameter is 20 mm, the length is 35 mm, and the inner wall roughness Ra≤0.2 μm to reduce particle retention.

[0030] The connecting pipe 200 includes an air inlet section 201 and a covering section 202 in sequence along the airflow direction.

[0031] In some optional examples, the connecting pipe may further include a guide section 203, which connects to the laser sensing cavity 100. If there is no guide section 203, then the covering section 202 connects to the laser sensing cavity 100. The inner diameters of the inlet section 201, the covering section 202, and the guide section 203 decrease sequentially to form a stepped flow channel. The sidewall of the covering section 202 is provided with at least one first clean air inlet 211, which connects to a clean airflow.

[0032] In one example, the inner diameter of the inlet section 201 of the connecting pipe 200 is 8-12 mm, for example, 8 mm, 9 mm, 11 mm, or 12 mm; the inner diameter of the covering section 202 is 6-9 mm, for example, 6 mm, 7.5 mm, 8 mm, or 9 mm; and the inner diameter of the guide section 203 is 4-6 mm, for example, 4 mm, 5 mm, or 6 mm. A first step 213 is provided between the inlet section 201 and the covering section 202, and a second step 214 is provided between the covering section 202 and the guide section 203. The inlet section 201, the covering section 202, and the guide section 203 can be integrally formed.

[0033] In one example, the three sections of the connecting pipe 200 are connected by a conical transition of 90°-120° to form a stepped flow channel. For example, if the angle is 90°, it forms an L-shaped step. If the angle is greater than 90°, such as 92°, 100°, 105°, 110°, 115°, or 120°, the conical surface gradually widens from the end face of the guide section 203. In one example, in the covering section 202, after a second step 214 of a certain width is retained on the end face of the guide section 203, the conical surface gradually widens towards the air intake section 201 to form a conical surface. Similarly, after a first step 213 of a certain width is retained on the end face of the covering section 202, the air intake section 201 gradually widens away from the covering section 202 to form a conical surface.

[0034] Multiple flow sensors are used, for example, a first flow sensor 460 is used to detect the flow rate of the clean airflow entering the laser sensing cavity 100 and connected to the first connecting pipe. A second flow sensor 450 is used to detect the flow rate of the clean airflow exiting the laser sensing cavity 100 and connected to the second connecting pipe.

[0035] A flow sensor that detects the total flow rate of the clean airflow and the airflow to be measured can be installed in the guide section.

[0036] In one example, the total length of the connecting tube 200 can be 20 mm to 40 mm, such as 20 mm, 28 mm, 32 mm, 36 mm or 40 mm.

[0037] In one example, the first clean air inlet 211 can be a through hole with a diameter of 1.2 mm to 4 mm, for example, the diameter can be 1.2 mm, 2 mm, 3 mm or 4 mm.

[0038] The first trachea 300 has one end inserted into the air intake section 201 and abutting against the first step 213 of the stepped flow channel, and the other end connected to at least the airflow to be measured.

[0039] The volumetric flow rate of the clean airflow is greater than that of the gas to be tested, so that the clean airflow forms an annular air curtain in the enveloping section 202 and completely envelops the gas to be tested before entering the laser sensing cavity 100.

[0040] The dust particle counter provided in this application embodiment is designed to cover the flow of the air to be measured with clean airflow, thereby preventing dust from falling into the laser sensing cavity 100, thus reducing optical path contamination and improving counting accuracy.

[0041] The laser sensing cavity 100 is a key area for optical particle detection, and it typically contains a laser emitter, an optical lens group, and a photodetector.

[0042] In this embodiment, the connecting pipe 200 serves as an airflow pretreatment unit. Its interior is precisely machined into an axially continuous channel consisting of an inlet section 201, a covering section 202, and a guide section 203. The inner diameters of these three sections decrease in a stepped manner, forming a stepped flow channel. The first air pipe 300 serves as the channel for the airflow to be measured. Its outlet end is inserted into the inlet section 201 and abuts against the first step 213 formed at the transition from the inlet section 201 to the covering section 202. The first clean air inlet 211 is located on the side wall of the covering section 202 to introduce clean, dry air (i.e., clean airflow) treated by the high-efficiency filter 500. Through precise flow control, the volumetric flow rate of the clean airflow is always greater than the volumetric flow rate of the airflow to be measured. After the clean airflow enters the covering section 202 with higher momentum from the first clean air inlet 211, due to the Venturi effect and fluid viscosity, it adheres tightly to the inner wall of the covering section 202, forming a high-speed, stable annular air curtain. This air curtain acts like a dynamic "clean air sleeve," completely enveloping and "suspending" the airflow to be tested from the first air duct 300, which is located at the center. Both flow together through the guide section 203 and finally enter the laser sensing cavity 100. During this process, dust particles in the airflow to be tested are constrained at the center of the clean air curtain, preventing them from contacting the flow channel wall and the subsequent inner wall of the cavity. This effectively prevents dust accumulation on the sensitive optical element from the source, ensuring the long-term detection accuracy of the dust particle counter.

[0043] In one embodiment, the sidewall of the guide section 203 is provided with at least one second clean air inlet 212, which is connected to the clean airflow.

[0044] In this embodiment, a second clean air inlet 212 is further provided on the side wall of the guide section 203. The guide section 203 serves as the last rectification channel before the airflow enters the laser sensing cavity 100, and its shape is typically a straight tube of equal diameter or a tapered tube. The purpose of providing the second clean air inlet 212 is to perform secondary shaping and kinetic energy replenishment on the airflow. When the main airflow (i.e., the airflow to be measured wrapped by the air curtain) passes through the covering section 202 and enters the narrower guide section 203, the flow field may be slightly disturbed. By supplementing the airflow with clean airflow through the second clean air inlet 212, the main airflow can be "refocused," the integrity of the annular air curtain can be strengthened, and the airflow can be smoothly injected into the laser sensing cavity 100 in a more stable state with a higher degree of laminarization. The provision of the second clean air inlet 212 enhances the stability of the dustproof air curtain at the end of the entire transmission path, avoids the local failure of the clean air curtain or the diffusion of the airflow to be measured due to abrupt changes in the flow channel, forms a double air curtain protection, and further improves the reliability of dust prevention.

[0045] In one embodiment, at least a portion of the inner surface of the first clean air inlet 211 is inclined in a direction from the outside to the inside toward the guide section 203, with an inclination angle of 15°-70°.

[0046] In this embodiment, the inner wall of the air inlet (i.e., the side facing the center of the flow channel) is designed as a slope with a specific angle. This slope is inclined towards the downstream guide section 203 along the airflow inlet direction (from the outside of the pipe to the inside), and the angle is preferably between 15° and 70°. For example, it can be designed with an angle of 15°, 30°, 45°, 50°, 60°, or 70°. This inclined structure is equivalent to a built-in guide plate or nozzle, which can more effectively guide the clean airflow, giving it a downstream axial velocity component after entering the flow channel, rather than just radial impact. This helps the clean airflow to adhere to the inner wall more quickly and smoothly, forming a forward-rotating annular flow, reducing eddies and energy loss at the airflow inlet, and making the formed annular air curtain more uniform, tighter, and with higher enveloping efficiency.

[0047] At least part of the inner surface of the arc can be, for example, the inner surface of the entire clean air inlet can be a closed annular side, which can be the left side tilted while the right side is not tilted.

[0048] In one example, at least part of the inner surface of the arc can also be inclined radially toward the stepped flow channel, so that the clean airflow cuts into the inner wall of the stepped flow channel and flows close to the inner wall to form an annular air curtain.

[0049] In one embodiment, the first clean air inlet 211 is cylindrical or conical. In the case of a conical shape, the larger opening of the cone faces outward and the smaller opening faces inward.

[0050] This application provides two preferred cross-sectional shapes for the first clean air inlet 211. The first is cylindrical, where the inlet is a short circular tube of uniform diameter, which is simple to manufacture and provides a stable airflow. The second is conical, with a converging design where the larger opening faces outward and the smaller opening faces inward. This conical opening acts as an accelerating nozzle. According to fluid mechanics principles, when the clean airflow passes through this converging cross-section, the velocity increases, and pressure energy is partially converted into kinetic energy. When the higher-velocity clean airflow enters the covering section 202 or the guide section 203, it has stronger momentum, can more rapidly sweep the inner wall, and form a stronger, less turbulent annular air curtain. At the same time, the smaller opening facing inward also limits the airflow diffusion angle, making the airflow more concentrated and directional, improving the utilization efficiency of the clean airflow and the formation quality of the air curtain.

[0051] In one embodiment, an annular slit is provided between the outlet end face of the first trachea 300 and the first step 213, and the width s of the annular slit satisfies 0.1mm≤s≤0.3mm.

[0052] In this embodiment, the outlet end face of the first air tube 300 is not completely sealed off from the first step 213. Instead, an annular slit with a width of s is retained, where 0.1 mm ≤ s ≤ 0.3 mm. This slit allows a very small portion of the clean airflow to seep back into the periphery of the outlet of the first air tube 300 before forming the main annular air curtain, creating a weak "pre-cleaning" airflow to sweep away particles that may be attached to the outer wall of the first air tube 300. This slit size prevents large particles from passing through, yet it is small enough to ensure that the vast majority of the clean airflow forms the main air curtain according to the designed path. It balances manufacturing tolerance tolerance, pre-cleaning function, and main airflow path fidelity, making the system more lenient in terms of assembly precision requirements while enhancing dustproof robustness. In one embodiment, the inner diameter of the first air tube 300 is smaller than the inner diameter of the covering section 202.

[0053] It is understandable that if the inner diameter of the first trachea 300 is too large, approaching the inner diameter of the covering section 202, it will compress or even block the annular flow channel of the clean airflow, causing the air curtain to fail to close completely in an annular shape or to have uneven thickness. By ensuring that the inner diameter of the first trachea 300 is smaller than the inner diameter of the covering section 202, it is ensured that the airflow to be tested is injected in the form of a relatively concentrated "core flow" with a small cross-section, while the clean airflow has sufficient space around it to expand and form a uniform and continuous air curtain layer, achieving a perfect "sheath flow" (the core flow is wrapped by the sheath flow) structure. This is the fluid dynamics basis for achieving efficient dust prevention and isolation.

[0054] In the above embodiment, the connecting pipe 200 includes an outlet dust particle counter located downstream of the covering section 202, which includes a first connecting pipe 220 and a second connecting pipe 210. The first connecting pipe 220 is an air inlet assembly, and its outlet end is connected to the air inlet of the laser sensing cavity 100, and the first air pipe 300 is connected to the gas source to be tested. The second connecting pipe 210 is an air outlet assembly, and its first air pipe 300 is connected to the gas discharged from the laser sensing cavity 100 after detection.

[0055] The connection between the outlet end of the first connecting tube 220 and the laser sensing cavity 100 can be a fixed connection that fits snugly or a fixed connection that is fast-plugged.

[0056] This application extends the application of the connecting pipe 200 from the air inlet end of the laser sensing cavity 100 to the air outlet end of the laser sensing cavity 100, forming a complete system-level dustproof solution. The connecting pipe 200 has an additional air outlet end downstream of the covering section 202, enabling a quick and reliable sealed connection with the laser sensing cavity 100 or other pipelines.

[0057] In this embodiment, the dust particle counter is configured with a first connecting pipe 220 (as an air inlet component) and a second connecting pipe 210 (as an air outlet component). The air inlet component is responsible for safely introducing the "test airflow enveloped by a clean air curtain" into the laser sensing cavity 100. The air outlet component works in the opposite way: its first air pipe 300 is connected to the cavity's exhaust port to lead out the detected waste gas; at the same time, clean airflow is still introduced from the clean air inlet of the second connecting pipe 210, establishing a "clean air plug" or "airlock" at the outlet of the laser sensing cavity 100. This ensures that the exhaust airflow is included by the clean airflow at the outlet end, preventing dust from falling into the outlet path, and also preventing external ambient air (which may contain dust) from flowing back into the cavity due to pressure difference. It also avoids the deposition of trace particles that may have diffused to the edge of the cavity due to turbulence at the outlet. The cooperation of the air inlet and outlet components is equivalent to constructing a dynamic, bidirectional clean airflow barrier for the laser sensing cavity 100, completely isolating the cavity from the external polluted environment.

[0058] In one embodiment, the clean airflow rate of the intake assembly is greater than the clean airflow rate of the exhaust assembly.

[0059] This application embodiment further specifies that the clean airflow rate of the inlet component is greater than that of the outlet component. This flow configuration strategy aims to actively control the pressure state inside the laser sensing cavity 100, maintaining a slightly positive pressure environment within the laser sensing cavity 100. Since the total amount of gas injected at the inlet end (clean + measured) is slightly greater than the total amount discharged at the outlet end, the excess clean gas will form a slight positive pressure within the cavity. This slightly positive pressure has two functions: First, it ensures that any possible leakage direction is outward, i.e., clean gas leaks outward, rather than external dusty air seeping inward. Second, the positive pressure environment helps suppress disordered eddies in the internal airflow, promoting directional and smooth airflow from the inlet end to the outlet end, further reducing the chance of particles colliding with the cavity wall due to random motion.

[0060] In one implementation, a controller is also included.

[0061] The controller is electrically connected to the flow sensor and is used to adjust the clean airflow rate of the first clean air inlet 211 and / or the second clean air inlet 212 according to the measurement value of the flow sensor.

[0062] This application embodiment realizes intelligent and adaptive adjustment of the dustproof air curtain. The system includes a clean airflow module (such as a precision proportional valve or speed-regulating pump, which can adjust the on / off state and flow rate of the clean airflow), a flow sensor, and a controller (such as an MCU). The flow sensor monitors the actual flow rate of the clean airflow or total airflow in real time and transmits the signal to the controller. The controller has a pre-stored algorithm (for example, setting the total clean airflow to K times the flow rate to be measured, where K>1). It dynamically calculates the required total amount of clean airflow based on the real-time measured flow rate to be measured and instructs the clean airflow module to proportionally adjust the flow rate entering the first and second clean air inlets 212. This achieves optimal air curtain coverage under different sampling flow rates (such as when the equipment is set to high, medium, and low sampling rates). The system can automatically adapt to changes in operating conditions and maintain stable and efficient dustproof performance under any sampling conditions. At the same time, it avoids excessive waste of clean gas at low sampling flow rates or the risk of dustproof failure when the sampling flow rate is suddenly increased, achieving accurate, efficient, and energy-saving intelligent dustproofing.

[0063] In one embodiment, the inner wall of the laser sensing cavity 100 is coated with a hydrophobic and oleophobic coating, the thickness of which is less than or equal to 10 μm.

[0064] This application embodiment adds a passive, materials-based protection layer to the inner wall of the laser sensing cavity 100 (especially the area through which the optical window and laser beam pass). An extremely thin hydrophobic and oleophobic coating is applied to its inner wall. The coating material can be a fluoropolymer or a silicon-based material, with a thickness controlled to ≤10μm to avoid affecting optical properties and cavity dimensions. The hydrophobic and oleophobic properties significantly reduce the adhesion force (van der Waals force) of most particles to the inner wall, making it difficult for dust particles to adhere stably. During the counting process, even a very small number of submicron-sized particles miraculously break through the dynamic air curtain's protection and come into contact with the inner wall of the cavity due to Brownian motion or extreme turbulence. Under the continuous blowing of clean airflow within the cavity, these "escaped dust particles" are easily carried away again, preventing them from gradually accumulating and forming dirt. This provides valuable "fault tolerance" and "self-cleaning" redundancy for the dynamic air curtain dust protection, complementing the active air curtain protection to jointly ensure the ultimate cleanliness of the laser sensing cavity 100, thereby guaranteeing long-term counting accuracy.

[0065] Example 2 The difference between this embodiment and Embodiment 1 is the structure of the connecting pipe 200. The connecting pipe 200 provided in this embodiment is as follows: Figures 4 to 6As shown, the connecting pipe 200 includes an inlet section 201 and a covering section 202. The covering section 202 covers the inlet section 201 in the radial direction, and the clean airflow channel of the covering section 202 covers the outside of the test airflow channel 400 of the inlet section 201. The clean airflow channel is an annular channel or includes multiple channels, which are evenly distributed around the test airflow channel 400.

[0066] This embodiment employs a connecting pipe 200 with a radially nested airflow structure. The inlet section 201 within this pipe forms the central flow channel for the airflow to be measured. The covering section 202 is not located downstream of the inlet section 201, but rather wraps around the inlet section 201 radially. The inlet section 201 (carrying at least the airflow to be measured) is nested within the covering section 202, and an annular, coaxial clean airflow channel 600 is formed between the inner wall of the covering section 202 and the outer wall of the inlet section 201. This annular clean airflow channel 600 is a preferred embodiment of the "clean airflow channel". Optionally, the clean airflow channel can also be composed of multiple independent, circumferentially uniformly distributed narrow straight grooves or small channels, which also surround the outside of the inlet section 201, collectively forming a distributed covering. The first air pipe serves as the input pipe for the airflow to be measured, with one end inserted into and connected to the inlet of the inlet section 201. During operation, the airflow to be measured enters the inlet section 201 through the first air pipe; simultaneously, a larger flow of clean airflow is injected into the annular (or multi-segment) clean airflow channel formed by the outer walls of the covering section 202 and the inlet section 201 through the first clean air inlet located on the side wall of the covering section 202. Other configurations of the dust particle counter in the above embodiment can employ various technical solutions now and in the future known to those skilled in the art, and will not be described in detail here.

[0067] This application also provides a dust particle counting method, applied to a dust particle counter described in any of the above embodiments, including: S410, clean airflow is introduced from the first clean air inlet 211.

[0068] The introduction of clean airflow through the first clean air inlet 211 is the start-up and pre-setting stage of the dust counting method. In practice, driven by the controller, the clean airflow module (such as a precision solenoid valve and flow controller) is first activated, simultaneously or sequentially introducing clean, dry air filtered by the high-efficiency filter 500 into the first clean air inlet 211 (located on the side wall of the covering section) and the optional second clean air inlet 212 (located on the side wall of the guide section) of the connecting pipe 200. This step precedes the introduction of the airflow to be measured 400, establishing a pure and stable "aerodynamic environment" within the laser sensing cavity 100 and its upstream flow channel. After entering, the clean airflow rapidly fills and purges the entire space from the connecting pipe 200 to the laser sensing cavity 100, pre-emptively removing any suspended particles that may remain in the pipes and cavity, and ensuring that the annular air curtain formation mechanism is ready. This allows a physical isolation barrier to be formed before the dust to be measured enters, preventing initial contact between the airflow to be measured 400 and potentially contaminated surfaces from the process flow.

[0069] S420, after the preset duration, the airflow to be measured 400 is introduced from the first trachea 300.

[0070] The preset duration can be 0.5 to 2 seconds, precisely timed by the controller. This ensures that the clean airflow introduced in step S410 has sufficient time to form a stable and complete annular air curtain within the encapsulation section, completely replacing the original gas in the cavity. In this case, the sampling pump starts, and the airflow to be tested 400 is drawn in through the first air tube 300. Since the clean air curtain is already stable and its flow rate is greater than that of the airflow to be tested 400, according to the principles of fluid dynamics, the airflow to be tested 400 will be completely enveloped in the center of the clean air curtain by the "sheath flow" effect, and the two form a stable laminar or quasi-laminar flow flowing forward together.

[0071] This application embodiment ensures that the dust prevention mechanism is activated before the risk of contamination through a strict timing control process. From the moment dust particles in the airflow to be measured 400 enter the system, they are confined to the center of the "clean air tunnel," and throughout their path through the laser sensing cavity 100, the particles do not come into contact with the cavity walls or optical components. This enforces physical isolation from an operational perspective, providing the most direct and effective methodological guarantee against dust accumulation within the sensitive cavity.

[0072] S430, obtain the counting result. In the counting result, the flow rate of the airflow to be measured 400 is the total airflow flow rate minus the flow rate of the clean airflow. The flow rate of the clean airflow includes the flow rates of the clean airflow in the first clean air inlet 211 and the second clean air inlet 212.

[0073] The flow rate of the measured airflow 400 is the total airflow rate minus the clean airflow rate. When performing optical counting, the dust particle counter detects all particles passing through the detection zone. However, due to the introduction of clean airflow in this method, the actual total airflow (Qt) passing through the detection zone of the laser sensing cavity 100 is the sum of the measured airflow 400 (Qs) and the clean airflow (Qc1 + Qc2). The total airflow can be obtained by a flow sensor. Qc1 and Qc2 are the flow rates introduced from the first and second clean air inlets 212, respectively, which are precisely controlled by the clean airflow module and fed back to the controller. Therefore, the actual sampled flow rate of the measured airflow 400, Qs = Qt - (Qc1 + Qc2). When calculating the final particle concentration per unit volume (e.g., particles / m³), the controller uses this corrected Qs as the denominator, eliminating the interference of the protective clean airflow on the concentration calculation and ensuring the accuracy of the counting results. Ensure the system provides strong dust protection while maintaining accurate quantitative analysis capabilities, thus achieving the dual goals of "dust prevention" and "accuracy." Ensure the output data is authentic and reliable.

[0074] In the description of this specification, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0076] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0077] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0078] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described above. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dust particle counter, characterized in that, include: Laser sensing cavity; A connecting pipe includes an air inlet section and a covering section; the air inlet section and the covering section are arranged sequentially along the airflow direction and their inner diameters decrease sequentially to form a stepped flow channel, or the covering section covers the air inlet section in the radial direction, and the clean airflow channel of the covering section covers the outside of the airflow channel to be tested of the air inlet section; the side wall of the covering section is provided with at least one first clean air inlet, and the first clean air inlet is connected to the clean airflow; A first trachea, one end of which is inserted into the air intake section, and the other end of which is connected to at least the airflow to be measured; Multiple flow sensors are used to detect the flow rate of the clean airflow and the total flow rate of the clean airflow and the airflow to be measured; The volumetric flow rate of the clean airflow is greater than that of the airflow to be measured, so that the clean airflow forms an annular air curtain that completely covers the airflow to be measured as it enters the laser sensing cavity.

2. The dust particle counter according to claim 1, characterized in that, The connecting pipe further includes a guide section. The air inlet section, the covering section and the guide section are arranged in sequence along the airflow direction, and the inner diameter decreases sequentially to form a stepped flow channel. The first air pipe abuts against the first step between the air inlet section and the covering section. The side wall of the guide section is provided with at least one second clean air inlet, which is connected to the clean airflow.

3. The dust particle counter according to claim 2, characterized in that, The inner surface of at least a portion of the arc of the first clean air inlet is inclined in a direction from the outside to the inside toward the guide section, with an inclination angle of 15°-70°.

4. The dust particle counter according to claim 2, characterized in that, The first clean air inlet is cylindrical or conical. In the case of a conical shape, the larger opening of the cone faces outward and the smaller opening faces inward.

5. The dust particle counter according to claim 2, characterized in that, The inner diameter of the first trachea is smaller than the inner diameter of the covered section.

6. The dust particle counter according to claim 1, characterized in that, The clean airflow channel is an annular channel or includes multiple channels, with the multiple channels evenly distributed around the airflow channel to be tested.

7. The dust particle counter according to any one of claims 2 to 6, characterized in that, The connecting pipe includes an air outlet located downstream of the covering section; the dust particle counter includes a first connecting pipe and a second connecting pipe; The first connecting pipe is an air inlet assembly, and its air outlet is connected to the air inlet of the laser sensing cavity. The first air pipe is connected to the gas source to be tested. The second connecting pipe is an exhaust assembly, which discharges gas from the laser sensing cavity after the first air pipe is connected to the detection.

8. The dust particle counter according to claim 7, characterized in that, The clean airflow rate of the air intake component is greater than that of the clean airflow rate of the air outlet component.

9. The dust particle counter according to claim 8, characterized in that, It also includes the controller; The controller is electrically connected to a plurality of the flow sensors and is used to adjust the clean airflow rate of the first clean air inlet and / or the second clean air inlet according to the measured values ​​of the flow sensors.

10. A method for counting dust particles, characterized in that, The dust particle counter according to any one of claims 1 to 9 comprises: A clean airflow is introduced from the first clean air inlet; After the preset duration, the airflow to be measured is introduced into the first trachea; Obtain the counting result; the flow rate of the airflow to be measured is the difference between the total flow rate and the flow rate of the clean airflow.

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