A particulate matter concentration measuring device and method thereof

Abstract

This invention provides a particulate matter concentration measuring device and method. The device includes: a light-emitting unit; a first laser light-transmitting window for isolating the light-emitting unit from the airflow to be detected while ensuring light transmission; a light trapping unit; a second laser light-transmitting window for isolating the light trapping unit from the airflow to be detected while ensuring light transmission; a main photoelectric sensor for measuring the particulate matter concentration by detecting laser light scattered by particulate matter in the airflow to be detected; a main photoelectric sensor light-transmitting window for isolating the main photoelectric sensor from the airflow to be detected while ensuring light transmission; a cleaning brush component for cleaning the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window; and a fan for providing forward and reverse airflow. This invention effectively achieves efficient and low-cost cleaning of the particulate matter concentration measuring device.

Description

Technical Field

[0001] This invention relates to the field of detection, and more specifically, to a particulate matter concentration measuring device and method thereof. Background Technology

[0002] Currently, particulate matter sensors using the laser scattering principle are widely used in gridded air micro-stations, construction site dust monitoring, and indoor environmental detection. They are characterized by simple structure, low cost, and high detection accuracy. However, existing products on the market also have some inherent defects:

[0003] 1) Existing particulate matter sensors have limited range, and may experience problems such as exceeding the range or inaccurate detection values ​​when used in environments with sandstorms or severe dust.

[0004] 2) Over time, dust accumulation can build up inside the airflow channel, especially around the photoelectric sensor, affecting detection accuracy. Manual cleaning is too costly. Sensors with backflushing cleaning capabilities have complex structures and high material costs.

[0005] 3) The light-emitting device used in conjunction with the photoelectric sensor may experience aging due to prolonged operation, leading to detection errors.

[0006] Patent application CN201910390162.3 discloses a technical solution that uses sheath flow technology to protect a photoelectric conversion device from particulate matter contamination in the measured airflow. By using filtered clean air to wrap the measured airflow, the photoelectric conversion device can avoid direct contact with particulate matter in the measured airflow, thereby reducing particulate matter contamination of the photoelectric conversion device.

[0007] However, sheath flow technology requires clean air, and the components that generate clean air also get dirty and require regular maintenance. In addition, protective gas can delay the time it takes for the photoelectric converter to become dirty, but it cannot completely prevent the photoelectric converter from getting dirty.

[0008] Patent application CN202110890608.6 discloses an automatic backflushing system for a particulate matter dust meter. The automatic backflushing system consists of a backflushing air pump, a three-way solenoid valve, and a data acquisition and control board. The data acquisition and control board controls the backflushing air pump and the three-way solenoid valve to open for backflushing and cleaning.

[0009] However, backflush pumps require additional backflush pumps and three-way valves, resulting in large system size and high cost. While general gas backflush can remove conventional dust accumulation in the air path, it cannot completely remove dust particles with strong adhesion to the surface of the photoelectric converter.

[0010] Therefore, conventional sheath flow technology and backflush pumps in the existing technology are not the optimal methods to solve the cleaning problem of particulate matter concentration measurement devices. Summary of the Invention

[0011] This invention provides a particulate matter concentration measuring device and method, wherein the laser transmission optical path and the airflow channel are isolated by a light-transmitting window, and the area where the light-emitting part and the photoelectric sensor are located is sealed and will not be contaminated by dust. The entire optical path can be cleaned by cleaning the surface of the light-transmitting window on the side of the airflow channel. Furthermore, by utilizing a fan reversing self-blowing cleaning structure, the particulate matter concentration measuring device can be cleaned efficiently and at low cost without the need for an additional back-blowing pump.

[0012] In a first aspect, the present invention provides a particulate matter concentration measuring device, characterized in that the device comprises:

[0013] The light-emitting part emits a laser beam used to measure the concentration of particulate matter in the airflow to be detected;

[0014] The first laser light-transmitting window is positioned in front of the light-emitting end of the light-emitting part to isolate the light-emitting part from the airflow to be detected while ensuring light transmission.

[0015] A light trapping unit includes a laser receiver for receiving laser light emitted by a light-emitting unit to prevent laser light reflection;

[0016] The second laser light-transmitting window is positioned in front of the laser receiving end of the light trap section to isolate the light trap section from the airflow to be detected while ensuring light transmission.

[0017] A main photoelectric sensor is used to measure the particle concentration by detecting laser light scattered by particles in the airflow to be detected;

[0018] The light-transmitting window of the main photoelectric sensor is positioned in front of the detection end of the main photoelectric sensor to isolate the main photoelectric sensor from the airflow to be detected while ensuring light transmission.

[0019] The cleaning brush component includes a first brush strip, a second brush strip, and a third brush strip, which are used to clean the first laser light transmission window, the second laser light transmission window, and the main photoelectric sensor light transmission window, respectively.

[0020] A fan is used to provide both forward and reverse airflow.

[0021] Secondly, the present invention also provides a method for measuring particulate matter concentration, characterized in that the method includes:

[0022] The light-emitting part emits a laser for measuring the concentration of particulate matter in the airflow to be detected;

[0023] By setting the first laser light-transmitting window in front of the light-emitting end of the light-emitting part, the light-emitting part is isolated from the airflow to be detected while ensuring light transmission.

[0024] The light trap section is a laser receiver that receives the laser light emitted by the light-emitting section to prevent laser reflection.

[0025] By setting a second laser light-transmitting window in front of the laser receiving end of the light trap section, the light trap section is isolated from the airflow to be detected while ensuring light transmission.

[0026] The main photoelectric sensor measures the particle concentration by detecting laser light scattered by particles in the airflow to be detected;

[0027] By setting a light-transmitting window for the main photoelectric sensor in front of the detection end of the main photoelectric sensor, the main photoelectric sensor is isolated from the airflow to be detected while ensuring light transmission;

[0028] The first, second, and third brush strips of the cleaning brush component clean the first laser light transmission window, the second laser light transmission window, and the main photoelectric sensor light transmission window, respectively.

[0029] The fan provides both forward and reverse airflow.

[0030] The particulate matter concentration measuring device and method provided by this invention are as follows: First, the light-emitting part and photoelectric sensor are isolated from the airflow to be detected by setting a light-transmitting window. The entire optical path can be cleaned by cleaning the surface of the light-transmitting window on the airflow channel side. Furthermore, the self-reverse fan cleaning structure eliminates the need for an additional back-flushing pump, achieving efficient and low-cost cleaning of the particulate matter concentration measuring device. Second, the use of a variable frequency fan and speed monitoring allows for control of the generation of a specified airflow rate. Variable flow rate particulate matter concentration calculation and optimal flow rate tracking algorithms allow for different flow rates to be used for different particulate matter concentrations, balancing the large range required for high concentrations and the high precision required for low concentrations. This results in a wider detection range and adaptability to harsh environments. Third, an auxiliary photoelectric sensor is used to assess the aging of the laser diode. An adjustable power light-emitting part driving circuit is added to control the light intensity, ensuring the system maintains a constant light intensity and preventing the detection error from increasing over time. This achieves component aging compensation, enabling the product to maintain long-term operational stability and accuracy. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is an external view of the particulate matter concentration measuring device 10 provided in an embodiment of the present invention;

[0033] Figure 2 This is an internal view of the particulate matter concentration measuring device 10 provided in an embodiment of the present invention;

[0034] Figure 3 This is an exploded view of the particulate matter concentration measuring device 10 provided in an embodiment of the present invention;

[0035] Figure 4 This is a diagram of a cleaning brush component for laser windows;

[0036] Figure 5 This is a diagram of a cleaning brush component for the sensor window;

[0037] Figure 6a and Figure 6b This is a diagram showing the status changes of the cleaning brush component used for laser windows;

[0038] Figure 7a and Figure 7b This is a diagram showing the status changes of the cleaning brush component at the sensor window;

[0039] Figure 8 This is a flowchart of the particulate matter concentration measurement method provided in the embodiments of the present invention;

[0040] Figure 9 This is a flowchart of the variable flow rate particulate matter detection procedure provided in an embodiment of the present invention;

[0041] Figure 10 This is a flowchart of the laser power stabilization procedure provided in an embodiment of the present invention. Detailed Implementation

[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Invention Overview

[0044] As mentioned above, the present invention provides a particulate matter concentration measuring device and method, which achieves efficient and low-cost cleaning of the particulate matter concentration measuring device.

[0045] Exemplary device

[0046] Figures 1-3 These are, respectively, an external view, an internal view, and an exploded view of the particulate matter concentration measuring device 10 provided in this embodiment of the invention. The device provided in this embodiment includes:

[0047] The light-emitting part 101 emits a laser for measuring the concentration of particulate matter in the airflow to be detected. For example, the light-emitting part can be a laser diode.

[0048] The first laser light-transmitting window 102 is disposed in front of the light-emitting end of the light-emitting part 101 to isolate the light-emitting part 101 from the airflow to be detected while ensuring light transmission.

[0049] The light trapping unit 103 includes a laser receiving end for receiving laser light emitted by the light emitting unit 101 to prevent laser light reflection.

[0050] Specifically, the laser that has passed through the detection zone is captured as soon as it reaches the light trap unit 103, thus avoiding reflection and secondary passage through the detection zone, which would cause errors in the particulate matter concentration measurement results.

[0051] The second laser light transmission window 104 is disposed in front of the laser receiving end of the light trap section 103 to isolate the light trap section 103 from the airflow to be detected while ensuring light transmission.

[0052] The main photoelectric sensor 105 is used to measure the particle concentration by detecting laser light scattered by particles in the airflow to be detected.

[0053] Specifically, the laser emitted by the light-emitting unit 101 will be scattered when it encounters particles in the airflow to be detected. The photoelectric sensor collects the intensity of the scattered light within a certain angle range, and linearly converts the angle of the scattered light and the corresponding intensity of the scattered light into voltage. Then, the measured angle and voltage are sent to the data processing system. The data processing system performs data processing according to the Mie scattering theory according to the pre-programmed program, and can obtain the equivalent particle size of the particles and the number of particles of different sizes per unit volume.

[0054] The main photoelectric sensor has a light-transmitting window 106, which is positioned in front of the detection end of the main photoelectric sensor 105 to isolate the main photoelectric sensor 105 from the airflow to be detected while ensuring light transmission.

[0055] The materials of the aforementioned light-transmitting windows 102, 104, and 106 are materials that are transparent to lasers, such as glass, acrylic, sapphire, etc., and are not limited here.

[0056] The cleaning brush component 107 includes a first brush bar 1171, a second brush bar 1172 and a third brush bar 1271, which are used to clean the first laser light transmission window 102, the second laser light transmission window 104 and the main photoelectric sensor light transmission window 106, respectively.

[0057] The brush bar includes a handle and a brush head. The handle can be made of polymer materials, bamboo, wood, etc. The brush head can be shaped like a scraper or bristles, and can be made of rubber, PA, PTFE, PBT, PE, PP, PVC, palm fiber, various animal and plant hairs, etc.

[0058] Fan 108 is used to provide both forward and reverse airflow.

[0059] The arrangement of the first laser light-transmitting window 102, the second laser light-transmitting window 104, and the main photoelectric sensor light-transmitting window 106 ensures that the area where the light-emitting part 101, the light trap part 103, and the main photoelectric sensor 105 are located is enclosed and will not be contaminated by particulate matter in the airflow to be detected. The entire optical path can be cleaned by cleaning the surfaces of these three light-transmitting windows on the airflow channel side, which greatly simplifies the difficulty of cleaning the light-emitting part 101 and the main photoelectric sensor 105.

[0060] Furthermore, the cleaning brush component 107 includes: a cleaning brush component 117 for the laser window, which is used to clean the first laser light transmission window 102 and the second laser light transmission window 104; and a cleaning brush component 127 for the sensor window, which is used to clean the light transmission window 106 of the main photoelectric sensor.

[0061] like Figure 4 As shown, the cleaning brush component 117 for the laser window includes a first driving surface 1173, a first brush bar 1171, a second brush bar 1172, a first starting surface 1174, and a first rotating shaft 1175.

[0062] The first brush bar 1171 and the second brush bar 1172, along with the first driving surface 1173, are all fixed to the first rotating shaft 1175. One side of the first driving surface 1173 is connected to the first starting surface 1174, and the first driving surface 1173 and the first starting surface 1174 form an obtuse angle. When in the opposite airflow direction, the starting surface is used to activate the first driving surface 1173 to swing to one side. The first driving surface 1173 and the first starting surface 1174 can also be smoothly transitioned into one piece by an arc, or the functions of the first driving surface 1173 and the first starting surface 1174 can be achieved by a single arc surface. Therefore, the first starting surface 1174 can be omitted, and this is not a limitation.

[0063] When the first driving surface 1173 is driven, the first brush bar 1171 and the second brush bar 1172 are driven by the first rotating shaft 1175 to clean the first laser light transmission window 102 and the second laser light transmission window 104 respectively.

[0064] like Figure 5 As shown, the sensor window cleaning brush component 127 includes a second driving surface 1272, a second starting surface 1273, and a second rotating shaft 1274.

[0065] One side of the second driving surface 1272 is the third brush strip 1271, which is used to clean the light-transmitting window 106 of the main photoelectric sensor.

[0066] The second driving surface 1272 is fixedly connected to a second rotating shaft 1274 perpendicular to the third brush bar 1271. One side of the second driving surface 1272 is connected to a second starting surface 1273, forming an obtuse angle between them. When in the opposite airflow direction, the second starting surface 1273 initiates the second driving surface 1272 to swing to one side. The second driving surface 1272 and the second starting surface 1273 can also be smoothly transitioned into one piece using an arc, or a single curved surface can be used to achieve the functions of both. Therefore, the second starting surface 1273 can be omitted, and this is not a limitation.

[0067] When the second driving surface 1272 is driven, it rotates around the second rotating axis 1274 and drives the third brush strip 1271 to clean the light-transmitting window 106 of the main photoelectric sensor.

[0068] In one embodiment, when in the normal airflow direction, i.e. the forward airflow direction, since the starting surface and the driving surface are connected at an obtuse angle, the first driving surface 1173 and the second driving surface 1272 of the cleaning brush component 107 remain in close contact with the inside of the airflow channel. When the forward airflow blows in, the driving surface cannot be activated to swing to one side.

[0069] When in the opposite airflow direction, the first starting surface 1174 and the second starting surface 1273 respectively activate the first driving surface 1173 and the second driving surface 1272 to swing to one side, and the brush strip of the cleaning brush component 107 sweeps across the light-transmitting window.

[0070] When the airflow direction is restored to the positive direction, the cleaning brush component 107 returns to its original position. Through repeated forward and reverse blowing, the cleaning brush component 107 cleans the light-transmitting window repeatedly.

[0071] Sectional view Figure 6a and Figure 6b Half of the cleaning brush component 117 for the laser window is shown. Figure 6a In normal working condition, the laser window cleaning brush component 117 is in close contact with the side wall and is maintained in position by the soft rubber damping that is in close contact with the glass window; Figure 6b The cleaning brush component 117 for the laser window brushes across the surface of the laser-transmitting window under the action of the reverse blowing force.

[0072] Figure 7a In normal working condition, the sensor window is held in place by the cleaning brush component 127 against the side wall and maintained in position by soft rubber damping. Figure 7b The cleaning brush component 127 brushes the surface of the light-transmitting window 106 of the main photoelectric sensor under the action of the back-blowing air force.

[0073] It should be noted that the relative positions of the cleaning brush component 117 for the laser window and the cleaning brush component 127 for the sensor window are compatible, and they will not collide or interfere with each other during cleaning. Figure 3 As shown in the exploded view of the device 10, the swing range of the second drive surface 1272 of the sensor window cleaning brush component 127 is between the two brush strips 1171 and 1172 of the laser window cleaning brush component 117.

[0074] When cleaning the light-transmitting window, the cleaning brush component 107 does not, but is not limited to, the repeated blowing of forward and reverse airflows mentioned above.

[0075] In another embodiment, the device 10 further includes an elastic system for resetting the cleaning brush component 107;

[0076] The first driving surface 1173 and the second driving surface 1272 of the cleaning brush component 107 are kept in close contact with the inside of the airflow channel by the elastic system under the normal airflow direction. The positive airflow will not generate blowing force on the first driving surface 1173 and the second driving surface 1272, and will not affect the detection.

[0077] When in the opposite airflow direction, the drive face of the cleaning brush component 107 swings to one side, and the brush strip of the cleaning brush component 107 sweeps across the light-transmitting window.

[0078] When the airflow stops, the cleaning brush component 107 returns to its original position using an elastic system. Through repeated back-blowing and stopping actions, the cleaning brush component 107 cleans the light-transmitting window repeatedly.

[0079] In the above embodiments, preferably, the reverse airflow velocity is higher than the forward airflow velocity. The reverse airflow can, on the one hand, drive the brush strip to clean the light-transmitting window through the driving surface; on the other hand, the gas blown back from the fan 108 to the detection area and then discharged through the air intake channel can blow out the accumulated dust and flocculent matter throughout the air path, thereby cleaning the entire air path.

[0080] When cleaning the light-transmitting window, the cleaning brush component 107 is not limited to the aforementioned wind-driven cleaning.

[0081] In another embodiment, the driving component of the cleaning brush component 107 is an independent driving component, such as a motor or electromagnet, used to drive the first brush strip 1171, the second brush strip 1172 and the third brush strip 1271 to clean the first laser light transmission window 102, the second laser light transmission window 104 and the main photoelectric sensor light transmission window 106. Due to the stronger driving capability, it is used in conjunction with a cleaning brush with greater adhesion.

[0082] Preferably, the fan 108 is a reversible speed-adjustable fan. By utilizing the reversible self-blowing cleaning structure of the fan 108, efficient and low-cost cleaning of the particulate matter concentration measuring device can be achieved without the need for an additional backflush pump.

[0083] In addition, to address the limited measurement range of existing particulate matter sensors, this invention employs a variable frequency fan and speed monitoring to control the generation of a specified airflow rate, a variable flow rate particulate matter concentration calculation and an optimal flow rate tracking algorithm, which uses different flow rates for different particulate matter concentrations, balancing the large measurement range required for high concentrations and the high precision required for low concentrations, resulting in a higher detection range and adaptability to harsh environments.

[0084] During normal operation, the fan rotates forward, and the airflow to be tested is drawn into the testing area through the air intake channel and then discharged from the outlet.

[0085] The speed of fan 108 is adjustable and the actual speed can be detected; it is used for:

[0086] By precisely controlling the speed of fan 108 to control the airflow rate, the corresponding relationship between the speed of fan 108 and the airflow rate is obtained.

[0087] Based on the correspondence between fan speed and airflow, a functional relationship between airflow velocity, particulate matter number, particulate matter size and particulate matter concentration is established so as to obtain particulate matter concentration under different airflow conditions.

[0088] When particulate matter concentrations are high, cross-interference and misjudgment can occur between particles. Using a low fan speed controls the number of particles, thereby reducing misjudgments and increasing the upper limit of concentration measurement. For example, when the fan speed is 1000 rpm, the measurement range for PM2.5 particulate matter concentration is 30 ppm to 1200 ppm, and when the fan speed is 2000 rpm, the measurement range is 10 ppm to 800 ppm. If the measured PM2.5 concentration is 800 ppm at a fan speed of 2000 rpm, reaching the upper limit of that speed, the fan speed is automatically reduced to 1000 rpm, and a more accurate value, such as 900 ppm, can be obtained by measuring again.

[0089] When the particulate matter concentration is low, the amount of particulate matter data detected in a certain period of time is too small to make accurate measurement. Using a high fan speed increases the number of particulate matter to make the measurement results more accurate and raises the lower limit of concentration measurement.

[0090] The fan speed is dynamically adjusted according to the actual particulate matter concentration to change the airflow velocity and achieve the ideal detection accuracy.

[0091] Specifically, an optimal fan speed tracking algorithm can be established based on the functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration.

[0092] Considering the power consumption and dust accumulation issues caused by different fan speeds, the device 10 allows the user to change the fan speed to achieve a balanced control of accuracy, power consumption, and dust accumulation.

[0093] Furthermore, the light-emitting part 101 is prone to aging and decay when turned on for a long time, which can lead to deviations in measurement results. As the decay increases, the measurement error also increases.

[0094] Therefore, the device also includes an auxiliary photoelectric sensor 109, which is independent of the main photoelectric sensor 105, for evaluating the actual light intensity. The auxiliary photoelectric sensor 109 is installed in the light trap section 103, enabling it to evaluate the light intensity of the entire light path, not limited to the aging evaluation of the light-emitting section 101, such as the attenuation of light due to dirt in the light-transmitting window can also be compensated accordingly.

[0095] When the assessed light intensity is below a predetermined threshold, a cleaning operation is initiated.

[0096] If the evaluated light intensity is still below a predetermined threshold after the cleaning operation, the power of the light-emitting unit 101 is adjusted so that the emitted laser always maintains a constant light intensity, thereby controlling the measurement error from increasing over time.

[0097] Exemplary methods

[0098] Accordingly, this invention also provides a method for measuring particulate matter concentration. Figure 8 This is a flowchart of the particulate matter concentration measurement method provided in the embodiments of the present invention, as follows: Figure 8 As shown, the method provided in this embodiment includes the following steps:

[0099] S801: The light-emitting part emits a laser for measuring the concentration of particulate matter in the airflow to be detected;

[0100] S802: By setting a first laser light-transmitting window in front of the light-emitting end of the light-emitting part, the light-emitting part is isolated from the airflow to be detected while ensuring light transmission;

[0101] S803: The laser receiving end of the light trap unit receives the laser emitted by the light emitting unit to prevent laser reflection;

[0102] S804: By setting a second laser light-transmitting window in front of the laser receiving end of the light trap section, the light trap section is isolated from the airflow to be detected while ensuring light transmission;

[0103] S805: The main photoelectric sensor measures the particle concentration by detecting the laser light scattered by the particles in the airflow to be detected;

[0104] S806: By setting a light-transmitting window of the main photoelectric sensor in front of the detection end of the main photoelectric sensor, the main photoelectric sensor is isolated from the airflow to be detected while ensuring light transmission;

[0105] S807: The first brush strip, the second brush strip, and the third brush strip of the cleaning brush component clean the first laser light transmission window, the second laser light transmission window, and the main photoelectric sensor light transmission window, respectively;

[0106] S808: The fan provides both forward and reverse airflow.

[0107] The cleaning brush component includes a cleaning brush component for the laser window and a cleaning brush component for the sensor window. Step S807 specifically includes:

[0108] The laser window cleaning brush component cleans the first laser light transmission window and the second laser light transmission window. Specifically, the laser window cleaning brush component includes a first driving surface, a first brush strip, a second brush strip, and a first rotating shaft. The first brush strip and the second brush strip are fixed to the first rotating shaft along with the first driving surface. When the first driving surface is driven, the first brush strip and the second brush strip are driven by the first rotating shaft to clean the first laser light transmission window and the second laser light transmission window respectively.

[0109] The sensor window is cleaned by a cleaning brush component to clean the light-transmitting window of the main photoelectric sensor. Specifically, the sensor window cleaning brush component includes a second driving surface and a second rotating shaft. One side of the second driving surface is the third brush strip, which is used to clean the light-transmitting window of the main photoelectric sensor. The second driving surface is fixedly connected to the second rotating shaft, which is perpendicular to the third brush strip. When the second driving surface is driven, it rotates around the second rotating shaft and drives the third brush strip to clean the light-transmitting window of the main photoelectric sensor.

[0110] More specifically, one side of the first driving surface and the second driving surface of the cleaning brush component are respectively connected to the first starting surface and the second starting surface. When in the opposite airflow direction, the starting surface is used to start the driving surface to swing to one side.

[0111] Preferably, the first driving surface and the second driving surface form an obtuse angle with the first starting surface and the second starting surface, respectively.

[0112] When in the opposite airflow direction, the starting surface is used to initiate the swing of the drive surface to one side. The drive surface and the starting surface can also be smoothly transitioned into one piece by an arc, or a whole arc surface can be used to realize the functions of the drive surface and the starting surface. Therefore, the starting surface can be omitted and is not limited here.

[0113] In one embodiment, when in the normal airflow direction, i.e., the forward airflow direction, the driving surface of the cleaning brush component remains in close contact with the interior of the airflow channel.

[0114] When in the opposite airflow direction, the first and second drive faces of the cleaning brush component swing to one side, and the brush bar of the cleaning brush component sweeps across the light-transmitting window;

[0115] When the airflow direction is restored to the positive direction, the cleaning brush component returns to its original position. Through repeated forward and reverse blowing, the cleaning brush component cleans the light-transmitting window repeatedly.

[0116] In another embodiment, when in the opposite airflow direction, the drive face of the cleaning brush component swings to one side, and the brush strip of the cleaning brush component sweeps across the light-transmitting window;

[0117] When the airflow stops, the cleaning brush component returns to its original position using an elastic system. Through repeated back-blowing and stopping actions, the cleaning brush component cleans the light-transmitting window repeatedly.

[0118] In the two wind-driven cleaning embodiments described above, preferably, the reverse airflow velocity is higher than the forward airflow velocity.

[0119] In another embodiment, the driving component of the cleaning brush component is a motor or an electromagnet, used to drive the first, second and third brush strips to clean the first laser light-transmitting window, the second laser light-transmitting window and the main photoelectric sensor light-transmitting window.

[0120] Preferably, the fan can be a reversible speed-adjustable fan, whose speed is adjustable and the actual speed can be detected.

[0121] In addition, to address the limited measurement range of existing particulate matter sensors, the method further includes:

[0122] By precisely controlling the fan speed to control the airflow rate, the corresponding relationship between fan speed and airflow rate is derived.

[0123] Establish a functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration based on the correspondence between fan speed and airflow rate;

[0124] An optimal fan speed tracking algorithm is established based on the functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration.

[0125] When the particulate matter concentration is high, use a low fan speed to control the number of particulate matter and increase the upper limit of concentration measurement.

[0126] When the particulate matter concentration is low, use a high fan speed to control the number of particulate matter and increase the lower limit of concentration measurement.

[0127] The fan speed is dynamically adjusted according to the actual particulate matter concentration to achieve ideal detection accuracy.

[0128] Considering the power consumption and dust accumulation issues caused by different fan speeds, the method allows the user to change the fan speed to achieve a balanced control of accuracy, power consumption, and dust accumulation.

[0129] One specific implementation method is as follows Figure 9 The flowchart shown is for the variable flow rate particulate matter detection program. The memory is responsible for providing the current preferred rotational speed value, the flow rate-particulate matter calculation parameter table, the optimal flow rate-concentration correspondence table, and the power consumption and accuracy balance settings.

[0130] After measurement begins, the fan is first turned on clockwise, followed by the light-emitting unit. Then, the current preferred speed value is read from memory to precisely control the fan speed. This preferred speed value defaults to low speed and is continuously updated. The main photoelectric sensor value is read, and the number and size of particles are calculated based on the flow rate-particle density calculation parameter table stored in memory. This further determines whether the actual detection time interval exceeds the specified detection time interval.

[0131] If the specified detection time interval is exceeded, the particle concentration of different particle sizes is calculated and output. The particle concentration and airflow velocity are calculated according to the optimal flow rate-concentration correspondence table stored in the memory and the power consumption and accuracy balance setting value specified by the user. The preferred fan speed value is updated and stored in the memory. It is then determined whether to end the measurement. If yes, the measurement ends. Otherwise, the measurement returns to the precise control of the fan speed based on the updated current preferred speed value stored in the memory.

[0132] If the specified detection time interval has not been exceeded, return to read the value of the main photoelectric sensor.

[0133] Furthermore, prolonged use of light-emitting devices can lead to aging and degradation, causing deviations in measurement results. To address this issue, the method further includes:

[0134] An auxiliary photoelectric sensor is used to evaluate the actual light intensity. This auxiliary photoelectric sensor is installed in the light trap unit, enabling it to evaluate the light intensity throughout the entire optical path.

[0135] When the assessed light intensity is below a predetermined threshold, a cleaning operation is initiated.

[0136] If the assessed light intensity is still below a predetermined threshold after the cleaning operation, the power of the light-emitting part is adjusted so that the emitted laser always maintains a constant light intensity.

[0137] One specific implementation method is as follows Figure 10 The flowchart shown illustrates the laser power stabilization procedure. The memory is responsible for providing the power adjustment value for the light-emitting unit and the target laser power value.

[0138] After the detection begins, the fan is first stopped, the light-emitting unit is turned on, and the power of the light-emitting unit is adjusted based on the laser tube power adjustment value stored in the memory. After a predetermined time delay (e.g., waiting for one minute), the airflow to be detected is stabilized before reading the value from the auxiliary photoelectric sensor. This further determines whether the value differs from the target laser power value stored in the memory.

[0139] If there is no difference, the test ends.

[0140] If there is a difference, determine whether the difference from the target laser power value is greater than the difference threshold:

[0141] 1. If the difference is greater than the threshold, determine whether the device has already undergone a cleaning operation:

[0142] 1. If a cleaning operation has been performed, calculate the power adjustment value of the light-emitting part, update the adjustment value, store the updated power adjustment value of the light-emitting part in the memory, and then end the detection;

[0143] 2. If no cleaning operation has been performed, self-cleaning will begin. The fan will start high-speed reverse rotation. After high-speed reverse rotation for a certain period of time, the fan will then rotate high-speed forward for a certain period of time. Then, it will be determined whether the specified number of forward and reverse rotation cycles has been exceeded. If yes, the fan will return to the stop fan step and the power of the light-emitting part will be checked again. Otherwise, the fan will continue to rotate high-speed reverse rotation.

[0144] 2. If the difference is less than the threshold, calculate the power adjustment value of the light-emitting part and update the adjustment value. Store the updated power adjustment value of the light-emitting part in the memory and end the detection.

[0145] It should be noted that although several devices, units, or modules of the particulate matter concentration measuring device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the invention, the features and functions of two or more modules described above can be embodied in one module. Conversely, the features and functions of one module described above can be further divided and embodied by multiple modules.

[0146] Furthermore, although the operation of the particulate matter concentration measurement method of the present invention is described in a specific order in the accompanying drawings, this does not require or imply that the operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0147] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A particulate matter concentration measuring device, characterized in that, The device includes: The light-emitting part emits a laser beam used to measure the concentration of particulate matter in the airflow to be detected; A light trapping unit includes a laser receiver for receiving laser light emitted by a light-emitting unit to prevent laser light reflection; A main photoelectric sensor is used to measure the particle concentration by detecting laser light scattered by particles in the airflow to be detected; At least one light-transmitting window is disposed before the detection end of the main photoelectric sensor to isolate the main photoelectric sensor from the airflow to be detected while ensuring light transmission; and / or it is disposed before the light-emitting end of the light-emitting part to isolate the light-emitting part from the airflow to be detected while ensuring light transmission; and / or it is disposed before the laser receiving end of the light trap part to isolate the light trap part from the airflow to be detected while ensuring light transmission. A cleaning brush component, including a brush strip for cleaning the light-transmitting window; A fan, which provides forward and reverse airflow to drive the brush bar; When in the opposite airflow direction, the brush strip sweeps across the light-transmitting window; When the airflow direction is restored to the positive direction, the brush bar returns to its original position. Through multiple changes in airflow direction, the cleaning brush component cleans the light-transmitting window repeatedly.

2. The particulate matter concentration measuring device according to claim 1, characterized in that, The cleaning brush component includes: The first laser light-transmitting window is positioned in front of the light-emitting end of the light-emitting part to isolate the light-emitting part from the airflow to be detected while ensuring light transmission. The second laser light-transmitting window is positioned in front of the laser receiving end of the light trap section to isolate the light trap section from the airflow to be detected while ensuring light transmission. The light-transmitting window of the main photoelectric sensor is positioned in front of the detection end of the main photoelectric sensor to isolate the main photoelectric sensor from the airflow to be detected while ensuring light transmission. The cleaning brush component includes a first brush strip, a second brush strip, and a third brush strip, which are used to clean the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window, respectively. A cleaning brush component for laser windows, used for cleaning the first laser light-transmitting window and the second laser light-transmitting window; and A cleaning brush component for the sensor window is used to clean the light-transmitting window of the main photoelectric sensor.

3. The particulate matter concentration measuring device according to claim 2, characterized in that, The cleaning brush component for the laser window includes a first driving surface, a first brush strip, a second brush strip, and a first rotating shaft; wherein The first brush strip and the second brush strip are fixed on the first rotating shaft along with the first driving surface. When the first driving surface is driven, the first brush strip and the second brush strip are driven by the first rotating shaft to clean the first laser light transmission window and the second laser light transmission window respectively.

4. The particulate matter concentration measuring device according to claim 3, characterized in that, The cleaning brush component for the sensor window includes a second driving surface and a second rotating shaft; One side of the second driving surface is the third brush strip, which is used to clean the light-transmitting window of the main photoelectric sensor; The second driving surface is fixedly connected to a second rotating shaft that is perpendicular to the third brush strip. When the second driving surface is driven, it rotates around the second rotating shaft and drives the third brush strip to clean the light-transmitting window of the main photoelectric sensor.

5. The particulate matter concentration measuring device according to any one of claims 4, characterized in that, The first driving surface and the second driving surface of the cleaning brush component are respectively connected to the first starting surface and the second starting surface. When in the opposite airflow direction, the starting surface is used to start the driving surface to swing to one side.

6. The particulate matter concentration measuring device according to claim 5, characterized in that, The first driving surface and the second driving surface form an obtuse angle with the first starting surface and the second starting surface, respectively.

7. The particulate matter concentration measuring device according to claim 5 or 6, characterized in that: When in the normal airflow direction, i.e. the positive airflow direction, the driving surface of the cleaning brush component remains in close contact with the inside of the airflow channel; When in the opposite airflow direction, the first and second drive faces of the cleaning brush component swing to one side, and the brush bar of the cleaning brush component sweeps across the light-transmitting window; When the airflow direction is restored to the positive direction, the cleaning brush component returns to its original position. Through repeated forward and reverse blowing, the cleaning brush component cleans the light-transmitting window repeatedly.

8. The particulate matter concentration measuring device according to claim 5 or 6, characterized in that, The device further includes: an elastic system for resetting the cleaning brush component; When in the opposite airflow direction, the drive face of the cleaning brush component swings to one side, and the brush strip of the cleaning brush component sweeps across the light-transmitting window; When the airflow stops, the cleaning brush component returns to its original position using an elastic system. Through repeated back-blowing and stopping actions, the cleaning brush component cleans the light-transmitting window repeatedly.

9. The particulate matter concentration measuring device according to claim 1, characterized in that, The wind speed of the reverse airflow is higher than that of the forward airflow.

10. The particulate matter concentration measuring device according to claim 2, characterized in that, The driving component of the cleaning brush assembly is a motor or electromagnet, used to drive the first, second and third brush strips to clean the first laser light-transmitting window, the second laser light-transmitting window and the main photoelectric sensor light-transmitting window.

11. The particulate matter concentration measuring device according to any one of claims 1-6, characterized in that, The fan is a reversible speed-adjustable fan, its speed is adjustable and the actual speed can be detected, and it is used for: By precisely controlling the fan speed to control the airflow rate, the corresponding relationship between fan speed and airflow rate is derived. Establish a functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration based on the correspondence between fan speed and airflow rate; When the particulate matter concentration is high, use a low fan speed to control the number of particulate matter and increase the upper limit of concentration measurement. When the particulate matter concentration is low, use a high fan speed to control the number of particulate matter and increase the lower limit of concentration measurement. The fan speed is dynamically adjusted according to the actual particulate matter concentration to achieve ideal detection accuracy.

12. The particulate matter concentration measuring device according to claim 1, characterized in that: An optimal fan speed tracking algorithm is established based on the functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration.

13. The particulate matter concentration measuring device according to claim 1, characterized in that: The device allows the user to adjust the fan speed to achieve a balance between accuracy, power consumption, and dust accumulation.

14. The particulate matter concentration measuring device according to claim 1, characterized in that, The device also includes an auxiliary photoelectric sensor for assessing the actual light intensity.

15. The particulate matter concentration measuring device according to claim 14, characterized in that, The auxiliary photoelectric sensor is installed in the light trap unit, enabling it to evaluate the light intensity of the entire optical path.

16. The particulate matter concentration measuring device according to claim 15, characterized in that, When the assessed light intensity is below a predetermined threshold, a cleaning operation is initiated.

17. The particulate matter concentration measuring device according to claim 16, characterized in that, If the assessed light intensity is still below a predetermined threshold after the cleaning operation, the power of the light-emitting part is adjusted so that the emitted laser maintains a constant light intensity.

18. A method for measuring particulate matter concentration, characterized in that, The method includes: The light-emitting part emits a laser for measuring the concentration of particulate matter in the airflow to be detected; By setting the first laser light-transmitting window in front of the light-emitting end of the light-emitting part, the light-emitting part is isolated from the airflow to be detected while ensuring light transmission. The light trap section is a laser receiver that receives the laser light emitted by the light-emitting section to prevent laser reflection. By setting a second laser light-transmitting window in front of the laser receiving end of the light trap section, the light trap section is isolated from the airflow to be detected while ensuring light transmission. The main photoelectric sensor measures the particle concentration by detecting laser light scattered by particles in the airflow to be detected; By setting a light-transmitting window for the main photoelectric sensor in front of the detection end of the main photoelectric sensor, the main photoelectric sensor is isolated from the airflow to be detected while ensuring light transmission; The brush strip of the cleaning brush component cleans the first laser light transmission window, the second laser light transmission window, and / or the light transmission window of the main photoelectric sensor; The fan provides both forward and reverse airflow to drive the brush bar; When in the opposite airflow direction, the brush bar sweeps across the light-transmitting window; wherein the light-transmitting window includes the first laser light-transmitting window, the second laser light-transmitting window and / or the main photoelectric sensor light-transmitting window; When the airflow direction is restored to the positive direction, the brush bar returns to its original position, and the light-transmitting window is cleaned repeatedly by changing the airflow direction multiple times.

19. The particulate matter concentration measurement method according to claim 18, characterized in that, The cleaning brush component includes a cleaning brush component for the laser window and a cleaning brush component for the sensor window. The specific steps of cleaning the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window by the first brush strip, the second brush strip, and the third brush strip of the cleaning brush component respectively include: The laser window is cleaned with a cleaning brush component to clean the first laser light transmission window and the second laser light transmission window; The sensor window is cleaned using a cleaning brush component to clean the light-transmitting window of the main photoelectric sensor.

20. The particulate matter concentration measurement method according to claim 19, characterized in that, The laser window cleaning brush component includes a first driving surface, a first brush strip, a second brush strip, and a first rotating shaft. The specific steps of cleaning the first and second laser light-transmitting windows using the laser window cleaning brush component include: The first brush strip and the second brush strip are fixed on the first rotating shaft along with the first driving surface. When the first driving surface is driven, the first brush strip and the second brush strip are driven by the first rotating shaft to clean the first laser light transmission window and the second laser light transmission window respectively.

21. The particulate matter concentration measurement method according to claim 20, characterized in that, The sensor window cleaning brush component includes a second driving surface and a second rotating shaft. One side of the second driving surface is the third brush strip. The third brush strip is used to clean the light-transmitting window of the main photoelectric sensor. The specific steps of the sensor window cleaning brush component cleaning the light-transmitting window of the main photoelectric sensor include: The second driving surface is fixedly connected to the second rotating shaft which is perpendicular to the third brush bar. When the second driving surface is driven, it rotates around the second rotating shaft and drives the third brush bar to clean the light-transmitting window of the main photoelectric sensor.

22. The particulate matter concentration measurement method according to claim 19, characterized in that, The steps of cleaning the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window respectively by the first brush strip, the second brush strip, and the third brush strip of the cleaning brush component further include: one side of the first driving surface and the second driving surface of the cleaning brush component are respectively connected to the first starting surface and the second starting surface, and when in the opposite airflow direction, the starting surface is used to start the driving surface to swing to one side.

23. The particulate matter concentration measurement method according to claim 22, characterized in that, The first driving surface and the second driving surface form an obtuse angle with the first starting surface and the second starting surface, respectively.

24. The particulate matter concentration measurement method according to claim 22, characterized in that, The steps of cleaning the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window respectively using the first brush strip, the second brush strip, and the third brush strip of the cleaning brush component further include: When in the normal airflow direction, i.e. the positive airflow direction, the driving surface of the cleaning brush component remains in close contact with the inside of the airflow channel; When in the opposite airflow direction, the first and second drive faces of the cleaning brush component swing to one side, and the brush bar of the cleaning brush component sweeps across the light-transmitting window; When the airflow direction is restored to the positive direction, the cleaning brush component returns to its original position. Through repeated forward and reverse blowing, the cleaning brush component cleans the light-transmitting window repeatedly.

25. The particulate matter concentration measurement method according to claim 22 or 23, characterized in that, The steps of cleaning the first laser light-transmitting window, the second laser light-transmitting window, and the main photoelectric sensor light-transmitting window respectively using the first brush strip, the second brush strip, and the third brush strip of the cleaning brush component further include: When in the opposite airflow direction, the drive face of the cleaning brush component swings to one side, and the brush strip of the cleaning brush component sweeps across the light-transmitting window; When the airflow stops, the cleaning brush component returns to its original position using an elastic system. Through repeated back-blowing and stopping actions, the cleaning brush component cleans the light-transmitting window repeatedly.

26. The method for measuring particulate matter concentration according to any one of claims 18-23, characterized in that, The wind speed of the reverse airflow is higher than that of the forward airflow.

27. The particulate matter concentration measurement method according to claim 19, characterized in that, The driving component of the cleaning brush assembly is a motor or electromagnet, used to drive the first, second and third brush strips to clean the first laser light-transmitting window, the second laser light-transmitting window and the main photoelectric sensor light-transmitting window.

28. The method for measuring particulate matter concentration according to any one of claims 18-23, characterized in that, The fan is a reversible speed-adjustable fan, its speed is adjustable and the actual speed can be detected, and the method further includes: By precisely controlling the fan speed to control the airflow rate, the corresponding relationship between fan speed and airflow rate is derived. Establish a functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration based on the correspondence between fan speed and airflow rate; When the particulate matter concentration is high, use a low fan speed to control the number of particulate matter and increase the upper limit of concentration measurement. When the particulate matter concentration is low, use a high fan speed to control the number of particulate matter and increase the lower limit of concentration measurement. The fan speed is dynamically adjusted according to the actual particulate matter concentration to achieve ideal detection accuracy.

29. The particulate matter concentration measurement method according to claim 18, characterized in that, The method further includes: An optimal fan speed tracking algorithm is established based on the functional relationship between airflow velocity, particulate matter number, particulate matter size, and particulate matter concentration.

30. The particulate matter concentration measurement method according to claim 18, characterized in that: The user can adjust the fan speed to achieve a balance between accuracy, power consumption, and dust accumulation.

31. The method for measuring particulate matter concentration according to any one of claims 18-23, characterized in that, The method also includes: using an auxiliary photoelectric sensor to assess the actual light intensity.

32. The particulate matter concentration measurement method according to claim 31, characterized in that, The auxiliary photoelectric sensor is installed in the light trap unit, enabling it to evaluate the light intensity of the entire optical path.

33. The particulate matter concentration measurement method according to claim 32, characterized in that, The method further includes initiating a cleaning operation when the assessed light intensity is below a predetermined threshold.

34. The particulate matter concentration measurement method according to claim 33, characterized in that, The method further includes: if the evaluated light intensity is still lower than a predetermined threshold after the cleaning operation, adjusting the power of the light-emitting part so that the emitted laser always maintains a constant light intensity.

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