Flow type braking particulate matter measuring system and method based on inertia test bed method

Abstract

The invention relates to the technical field of automobile emission testing, in particular to a flowing type braking particulate matter measuring system and method based on an inertia test bed method, and the method comprises the steps that a cooling air conditioning system provides filtered cooling air; the brake test cabin is provided with a brake, the brake test cabin is arranged on the inertia test bench, and the inertia test bench drives the brake to rotate; the brake test cabin is communicated with the cooling air conditioning system through a pipeline to form a measuring pipeline; a wind speed sensor is arranged at the inlet of the brake test cabin to measure the wind speed at the inlet of the brake test cabin; the measuring pipeline is provided with a monitoring unit for monitoring environment information of the measuring pipeline, and the particulate matter sampling and analyzing equipment is used for collecting brake wear particulate matters and sample gas in the measuring pipeline and analyzing the quantity and the quality of the brake wear particulate matters. According to the scheme, flow type braking particulate matter measurement is carried out, the test authenticity can be improved, external interference is avoided, the aerosol mixing uniformity is guaranteed, and the measurement accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of automotive emissions testing technology, specifically to a flow-type braking particulate matter measurement system and method based on the inertial test bench method. Background Technology

[0002] With the continuous increase in the number of vehicles, the problem of particulate matter emissions from motor vehicles is becoming increasingly prominent. Particulate matter emitted by motor vehicles includes not only traditional exhaust emissions but also non-exhaust emissions such as brake wear, tire wear, road surface wear, and road dust. Among these, brake wear particulate matter (BRPM) is a significant component of non-exhaust particulate matter, contributing 11%-21% of total traffic-related PM10 emissions and 20%-55% of non-exhaust PM10 emissions. BRPM not only causes environmental pollution but also has a significant impact on human health because it contains many chemical components that affect human health.

[0003] Common methods for measuring brake wear particulate matter include test methods and real-road test methods. Test methods combine data on vehicle braking characteristics with vehicle dynamics, reproducing the braking cycle using a brake particulate matter emission collection and analysis system under various conditions to obtain results. Real-road test methods install a real-time brake particulate matter emission collection and analysis device on the vehicle being tested to obtain data on braking conditions during vehicle operation, as well as data on particulate matter concentration, quantity, and size distribution during braking. However, these methods all have certain limitations. Test methods are too idealistic and cannot truly reflect the emission characteristics of brake particles during actual vehicle travel. Real-road test methods also struggle to distinguish particulate matter generated by braking friction from aerosols generated by other traffic and particulate matter in the outside air.

[0004] To address the aforementioned issues, a braking particulate matter testing system was established, providing a cyclic testing environment to improve test accuracy and avoid interference from particulate matter in the outside air. However, uneven aerosol mixing during the testing process may affect the accuracy of the measurement results.

[0005] Therefore, there is an urgent need for a flow-type braking particulate matter measurement system and method based on the inertial test bench method. This method can improve the authenticity of the test, reduce external interference, and ensure the uniformity of aerosol mixing, thereby improving the accuracy of the measurement. Summary of the Invention

[0006] One of the objectives of this invention is to provide a flow-type braking particulate matter measurement system based on the inertial test bench method. This system can improve the authenticity of the test, reduce external interference, and ensure the uniformity of aerosol mixing, thereby improving the accuracy of the measurement.

[0007] The first basic solution provided by this invention is a flow-type braking particulate matter measurement system based on the inertial test bench method, comprising: a cooling air conditioning system, an inertial test bench, and a braking test chamber; Cooling air conditioning system, used to provide the filtered air required for measurement; Brake test chamber, used to install different types of brakes; The braking test chamber is set on an inertial test bench, which is used to simulate the kinetic energy of a moving car, causing the brakes in the braking test chamber to rotate. Furthermore, the braking test chamber and the cooling air conditioning system are connected by pipes to form a measurement pipeline; a wind speed sensor is installed at the entrance of the braking test chamber to measure the wind speed at the entrance of the braking test chamber; The measuring pipeline is equipped with a monitoring unit and particulate matter sampling and analysis equipment; The monitoring unit is used to monitor and measure environmental information from the pipeline. Particulate matter sampling and analysis equipment is used to collect brake wear particles and sample gas from the measurement pipeline, and to analyze the quantity and quality of brake wear particles.

[0008] The second objective of this invention is to provide a method for measuring particulate matter in flowing braking systems based on an inertial test bench. This method improves the authenticity of the test, avoids external interference, and ensures the uniformity of aerosol mixing, thereby enhancing the accuracy of the measurement.

[0009] This invention provides a second basic solution: a method for measuring particulate matter in flowing braking systems based on an inertial test bench, employing the aforementioned system for measuring particulate matter in flowing braking systems based on an inertial test bench, comprising: S1. The cooling air conditioning system starts, providing cooling air to the measurement pipeline at preset temperature, preset humidity, and preset flow rate. The monitoring unit monitors the environmental information of the measurement pipeline throughout the process and feeds it back to the control system. The control system controls the operation of the cooling air conditioning system and the inertial test bench based on the feedback environmental information. S2. Test the wind speed using a wind speed sensor, measure the wind speed value at the entrance of the braking test chamber, and determine if the wind speed is consistent. If yes, proceed to S3; otherwise, adjust the airflow using the cooling air conditioning system and then proceed to S2 again. S3. Install the brakes. Cooling air, after passing through the filter, enters the brake test chamber through the ventilation duct. The inertial test bench drives the brakes inside the test chamber to rotate, simulating the acceleration, cruising, and braking deceleration processes under real driving conditions, generating wear particles, which are released into the cooling air. S4. The wear particles generated during the braking process form a uniform aerosol with the cooling air and are transported to the sampling plane by the airflow. The particulate matter sampling and analysis equipment collects particulate matter samples on the sampling plane and analyzes and measures the particulate matter according to its category to obtain the measurement results.

[0010] Beneficial Effects: In this solution, the cooling air conditioning system, inertial test bench, and brake test chamber form a measurement pipeline. The brake test chamber is located on the inertial test bench, which simulates the kinetic energy of a moving vehicle, causing the brakes in the test chamber to rotate, thus simulating the operation and use of the brakes during actual vehicle operation. The cooling air conditioning system provides the cooling air required for the measurement, which flows through the measurement pipeline. A monitoring unit is installed on the measurement pipeline to monitor the environmental information of the pipeline. Particulate matter sampling and analysis equipment is used to collect brake wear particles and sample air from the measurement pipeline, and analyze the quantity and mass of brake wear particles, thereby completing the flow-type brake particulate matter measurement. The measurement loop formed by the inertial test bench method can avoid the interference of environmental particulate matter because the cooling air provided by the cooling air conditioning system is filtered. At the same time, the particle emission generated by brake wear is closer to the actual situation. It has the advantages of high test accuracy and repeatability, making it the most reliable method for testing and certification. Furthermore, the setting of the monitoring unit can ensure the consistency of the test environment.

[0011] Specifically, a wind speed sensor is installed at the entrance of the brake test chamber in this scheme to measure the wind speed at the entrance of the brake test chamber. When the system is tested, it involves a complex dynamic state of fluid-solid particle-thermodynamic coupling. In order to ensure the uniformity of aerosol mixing, it is necessary to verify the consistency of the wind speed at the entrance of the brake test chamber through the wind speed sensor.

[0012] In summary, this method for measuring particulate matter in flowing brake systems can improve the authenticity of the test, avoid external interference, and ensure the uniformity of aerosol mixing, thereby improving the accuracy of the measurement. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the inertial test bench structure of an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 2 This is a schematic diagram of the open measurement pipeline in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 3 This is a schematic diagram of a closed measurement pipeline in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 4This is a plan view of the braking test chamber in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 5 This is a schematic diagram showing the installation position of the wind speed sensor in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 6 This is a schematic diagram of the sampling probe layout in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 7 This is a schematic diagram showing the bending radius in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention; Figure 8 This is a data diagram of the emission test process in an embodiment of the flow-type braking particulate matter measurement system based on the inertial test bench method of the present invention. Detailed Implementation

[0014] The following detailed description illustrates the specific implementation methods: The markings in the accompanying drawings include: 1. Cooling air conditioning system; 2. Braking test chamber; 3. Particulate matter sampling and analysis equipment; 4. Monitoring unit; 5. Sampling plane; 6. Inertial test bench; 6. Base; 601. Support frame; 602. Drive motor; 603.

[0015] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connection," "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0016] In the description of this specification, it should be understood that the directional terms such as "upper," "lower," "left," and "right" used in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should also be understood that when referring to an element being connected to another element "upper," "lower," "left," or "right," it can be directly connected to the other element "upper," "lower," "left," or "right," or indirectly connected through an intermediate element.

[0017] Example 1 This embodiment provides a flow-type braking particulate matter measurement system based on the inertial test bench method, including: a cooling air conditioning system 1, an inertial test bench 6, a braking test chamber 2, a particulate matter sampling and analysis device 3, and a monitoring unit 4; Cooling air conditioning system 1, used to provide the filtered air required for measurement; Specifically, the cooling air conditioning system 1 includes: a compressed air source, a condenser, a thermostat, an expansion valve, and a fan; The compressed air source is connected to the brake installed in the brake test chamber 2 via a pipeline to provide cooling air to the brake; the condenser is used to convert gas into liquid, in this embodiment, it converts high temperature and high pressure (temperature exceeding 100 degrees and pressure higher than atmospheric pressure) gas into normal temperature and pressure (temperature 25±c℃, c is an error constant, pressure one standard atmosphere) liquid; the thermostat is used to control the temperature of the cooling air; the expansion valve is used to regulate the flow rate of the cooling air; and the fan is used to send the cooling air into the brake.

[0018] To ensure that the regulated cooling air meets the temperature and humidity requirements, the cooling air conditioning system 1 is equipped with a condenser, thermostat, and expansion valve. The cooling air conditioning system 1 employs closed-loop proportional-integral / derivative control and monitors the status of all equipment and interfaces through sensors in the monitoring unit 4. In other embodiments, an alarm can be installed for alarm functions. The minimum flow rate Qmin and maximum operating flow rate Qmax of the cooling air conditioning system 1 are controlled as follows: 100 ≤ Qmin ≤ 300 m³ / h, Qmax ≥ 5Qmin; Qmax - Qmin ≥ 1000 m³ / h. This system should continuously monitor and control the temperature and humidity of the air conditioning cooling air. Therefore, temperature and humidity sensors are installed in monitoring unit 4. The stability of the cooling air temperature and humidity is evaluated through sensor feedback signals. To avoid the influence of the temperature feedback signal by the heat load generated by braking, the sensor is installed upstream of the braking test chamber 2. The minimum accuracy of the temperature sensor is ±1℃. The sensor used to measure absolute and relative humidity has a rated value of 50% and a test accuracy of ±5% of the rated value. The sampling frequency for cooling air temperature, humidity, and flow rate of this system is 1Hz. The requirements for the rated value, the maximum permissible deviation of the average value, and the maximum permissible deviation of the instantaneous value are shown in Table 1. Table 1: Temperature, Humidity, and Flow Rate Requirements The brake test chamber 2 is set on the inertial test bench 6; the brake test chamber 2 is used to install different types of brakes; the inertial test bench 6 is used to simulate the kinetic energy of a moving car, driving the brakes in the brake test chamber 2 to rotate. Specifically, such as Figure 1As shown, the inertial test bench 6 includes a base 601, a support frame 602, and a drive motor 603; The base 601 is used to fix the brake test chamber 2; the support frame 602 is installed on the base 601 to support the brake test chamber 2; the drive motor 603 is installed on the support frame 602 to simulate the kinetic energy of a car and drive the brake test chamber 2 to move.

[0019] Braking test chamber 2 and cooling air conditioning system 1 are connected by pipes to form a measurement pipeline; Specifically, the brake test chamber 2 is a sealed structure with brake mounting slots inside, and different types of brakes are installed using different tooling. The brake test chamber 2 has an air inlet on one side and an air outlet on the other. The air inlet of the brake test chamber is connected to the air outlet of the cooling air conditioning system via a pipe. Both the air outlet of the brake test chamber and the air inlet of the cooling air conditioning system are connected to pipes, forming an open measurement pipeline. Figure 2 As shown; Alternatively, the air inlet and outlet of the brake test chamber are connected to the air outlet and inlet of the cooling air conditioning system via pipes, forming a closed measurement pipeline, such as... Figure 3 As shown; Open-type measurement pipelines can exhaust exhaust gases, placing lower demands on the filtration requirements of the cooling air conditioning system and facilitating practical applications; closed-type measurement pipelines, while requiring higher filtration standards from the cooling air conditioning system, can completely avoid interference from environmental particulate matter. The specific piping setup is as follows: Open measurement piping: The straight pipe connected to the air inlet of brake test chamber 2 is the first straight pipe, the straight pipe connected to the air outlet of brake test chamber 2 is the second straight pipe, and the straight pipe connected to the end of the second straight pipe that is not connected to the air outlet through the first bend is the third straight pipe; The air inlet of the cooling air conditioning system 1 is connected to the fourth straight pipe, the air outlet of the cooling air conditioning system 1 is connected to the fifth straight pipe, the end of the fifth straight pipe that is not connected to the air outlet of the cooling air conditioning system 1 is connected to the sixth straight pipe through the third bend, and the end of the sixth straight pipe that is not connected to the third bend is connected to the end of the first straight pipe that is not connected to the air inlet of the brake test chamber 2 through the fourth bend.

[0020] The closed measuring pipeline is a rectangular measuring pipeline; The straight pipe connected to the air inlet of the brake test chamber 2 is the first straight pipe, the straight pipe connected to the air outlet of the brake test chamber 2 is the second straight pipe, the straight pipe connected at the end of the second straight pipe that is not connected to the air outlet through the first bend is the third straight pipe, the straight pipe connected at the end of the third straight pipe that is not connected to the first bend through the second bend is the fourth straight pipe, the end of the fourth straight pipe that is not connected to the second bend is connected to the air inlet of the cooling air conditioning system 1, the straight pipe connected to the air outlet of the cooling air conditioning system 1 is the fifth straight pipe, the straight pipe connected at the end of the fifth straight pipe that is not connected to the air outlet of the cooling air conditioning system 1 through the third bend is the sixth straight pipe, and the end of the sixth straight pipe that is not connected to the third bend is connected to the end of the first straight pipe that is not connected to the air inlet of the brake test chamber 2 through the fourth bend.

[0021] In this embodiment, the dimensions of the brake test chamber 2 should meet the requirements of the test equipment during the test, including the target speed, braking test inertia, and braking torque capacity. An overly large brake test chamber 2 may result in low-pressure areas, leading to lower air velocities to meet the brake's target temperature and longer particle delivery times. The main dimensions of the brake test chamber 2 are as follows: Figure 4 As shown, where: A is the test chamber exit plane; A1 is the test chamber lateral symmetry line; B is the transition zone cutoff plane; A2 is the longitudinal symmetry line; α is the transition section angle; h A h is the height of the cutoff plane in the transition region. B This refers to the maximum height of the test chamber; A1 The maximum length of the test chamber; l i d represents the length of the transition zone; d represents the inlet and outlet pipe diameters of the test chamber. The dimensional requirements for brake test chamber 2 are as follows: Brake test chamber 2 is designed longitudinally symmetrically according to plane A1, 1200mm ≤ lA1 ≤ 1400mm; Brake test chamber 2 is designed laterally symmetrically according to plane A2, 600mm ≤ hD ≤ 750mm; h A / hB >60%; i =h A ;d=d i To avoid sudden changes in the cross-sectional shape and size of the transition region, ensure a smooth transition angle of 15°≤α≤30°.

[0022] A wind speed sensor is installed at the entrance of the brake test chamber 2 to measure the wind speed at the entrance of the brake test chamber 2; Specifically, the braking particulate matter measurement system involves a complex dynamic state of fluid-solid particle-thermodynamic coupling. In order to ensure the uniformity of aerosol mixing, it is necessary to verify the consistency of the wind speed at the inlet of the braking test chamber 2 through a wind speed sensor.

[0023] In this embodiment, a wind speed sensor is installed to measure the wind speed at several measurement locations at the entrance of the brake test chamber 2. Specifically, a rectangular frame with a length and width greater than the diameter of the brake is set, and the wind speed values ​​at the center nine points of each of the nine squares are evenly distributed within the rectangular frame. Without installing the brake assembly or brake clamp, the wind speed is measured as follows: Figure 4 The wind speed values ​​at nine locations in plane C are shown; during these measurements, all cooling air ducts used for brake emission testing should remain connected to the brake test chamber.

[0024] The measuring pipeline is equipped with particulate matter sampling and analysis equipment 3 and monitoring unit 4; The particulate matter sampling and analysis device 3 is used to collect brake wear particles and sample gas from the measurement pipeline, and to analyze the quantity and mass of brake wear particles; Specifically, the particulate matter sampling and analysis device 3 includes a sampling probe, a sampling tube, and an analyzer; The sampling probe is installed on sampling plane 5 to collect braking particulate matter; Sampling tubes are used to transport sample gas to analytical equipment; The analyzer is used to analyze the quantity and quality of brake particulate matter. Figure 2 and Figure 3 In this context, PM2.5 represents particulate matter with a cutoff diameter of 2.5 μm; PM10 represents particulate matter with a cutoff diameter of 10 μm; SPN represents the solid particle number; SPN10 represents the number of solid particles with a diameter greater than 10 nm; TPN represents the total particle number; TPN10 represents the total number of particles with a diameter greater than 10 nm. The sampling probe is set on the second right straight tube and is set as the sampling plane 5. The second straight tube is divided into a second left straight tube and a second right straight tube. The second right straight tube is connected to the outlet of the brake test chamber 2, and the second left straight tube is connected to the first bend. Sampling plane 5 is the plane formed by the inlets of the four sampling probes (PM2.5, PM10, SPN10, and TPN10) in the sampling channel. It is perpendicular to the airflow direction. The layout requirements of the sampling probes are as follows: Figure 6 As shown. PM and particulate number (PN) sampling locations should be within the same cross-sectional area of ​​the sampling channel. Sampling probes are equidistantly arranged along the central longitudinal axis of the sampling channel, with a minimum distance 'a' between each sampling probe being 47.5 mm, and a minimum radial distance of 47.5 mm between the sampling probe and the pipe wall (distance measurement is performed using the outer diameter of the sampling probe).

[0025] In this embodiment, the second straight pipe serves as the sampling channel. In other embodiments, the sampling channel can be set as a bent pipe, or the sampling probe can be placed on the first bent pipe. However, regardless of the setting method, the design of the sampling channel should meet the following requirements: cooling air should flow through a circular pipe, and the cross-section between the outlet of the brake test chamber 2 and the sampling plane 5 should remain unchanged; the channel surface in contact with aerosol needs to be made of electropolished stainless steel or other equivalent materials; any transition between adjacent sections should be free of potential BWP accumulation defects or features; 190≤d i ≤225mm; the bending angle of the sampling channel should be ≤90°; if there is no bending in the sampling channel, a section with a length of at least 6d should be installed between the outlet of the brake test chamber 2 and the sampling plane 5. i For a straight pipe, if there is a bend in the sampling channel, the bend radius r b ≥2d i , where r b Definition as follows Figure 7 As shown; in addition, when the sampling channel is curved, a length ≥6d should be set before the sampling plane 5 and after the curve. i Straight pipe.

[0026] Monitoring unit 4 is used to monitor and measure environmental information of the pipeline; Specifically, in this embodiment, the monitoring unit 4 includes several sensors, including a temperature sensor, a humidity sensor, a pressure sensor, and a flow sensor, for monitoring and measuring the temperature, humidity, pressure, and flow rate of the pipeline; Temperature, humidity, pressure, and flow sensors are installed at different points in the measuring pipeline to monitor the temperature, humidity, pressure, and flow rate of the test environment in real time and feed the data back to the control system. Figure 2 and 3 As shown, the temperature and humidity sensors are installed on the right, and the pressure and flow sensors are installed on the left. The sensor signal lines are connected to the external system via data lines, and digital signal processing is used for data acquisition and control. The monitoring unit 4 is installed on the third straight pipe, which is divided into a third upper straight pipe and a third lower straight pipe. The third upper straight pipe is connected to the first bend pipe, and the third lower straight pipe in the closed measuring pipeline is connected to the second bend pipe. The above pipe size design requirements are as follows: L1≥2d i L2≥6d i L3≥2d i L4≥2d i L5≥5d i Where L1 is the length of the first pipe, L2 is the length of the second right pipe, L3 is the length of the second left pipe, L4 is the length of the third upper pipe, L5 is the length of the third lower pipe, and d iThe diameter is the diameter of the straight pipe.

[0027] The inner walls of the pipes are made of stainless steel with an electropolished surface (or equivalent surface) and are equipped with multiple pipe supports to fix the pipes and maintain their stability.

[0028] This embodiment also provides a method for measuring particulate matter in flowing braking systems based on the inertial test bench method. The method employs the aforementioned particulate matter measurement system for flowing braking systems based on the inertial test bench method, and includes the following components: S1. The cooling air conditioning system 1 is activated, providing cooling air to the measuring pipeline at a preset temperature, humidity, and flow rate. The monitoring unit 4 monitors the temperature, humidity, and flow rate of the measuring pipeline throughout the process. In other embodiments, the monitoring data is fed back to the control system, which then controls the operation of the cooling air conditioning system 1 and the inertial test bench 6 based on the feedback temperature, humidity, and flow rate. In this embodiment, the blower of the cooling air conditioning system 1 provides the test system with cooling air at a specific temperature, humidity, and flow rate. The preset temperature is 23±2℃, the preset humidity is 45~55%, and the preset flow rate is 720m³ / h. 3 ·h -1 .

[0029] S2. Measure the wind speed at the inlet of the braking test chamber 2 using a wind speed sensor to determine if the wind speed is consistent. If so, proceed to S3; otherwise, adjust the airflow using the cooling air conditioning system 1 and then proceed to S2 again. Specifically, the wind speed verification should ensure that the requirements are met simultaneously at both the minimum (300 m³ / h) and maximum (1500 m³ / h) operating flow rates of the measurement pipeline. Before each measurement, the cooling air should be stabilized for at least 2 minutes. When the cooling air flow rate reaches within 5% of the set value, the airflow is considered to have reached a stable state. If the wind speed variation in each area of ​​the nine-square grid does not exceed 35% of the arithmetic mean of all measured values ​​for the set air flow rate, the wind speed uniformity verification is considered passed. The wind speed verification results are shown in the table below. Under the three cooling air flow rates, the wind speed at each location is less than 35% of the arithmetic mean of all measured values, indicating that the wind speed meets the requirements of the test system. The distribution of the nine measuring points at plane C is shown in Table 2: Table 2: Distribution of measuring points at nine locations on plane C The measurement sequence, corresponding to Table 2, is shown in Table 3: Table 3: Measurement Sequence Plane C has dimensions of 500mm width, 576mm height, and an area of ​​0.288m². 2 ; The average wind speed measured over two minutes, i.e., air velocity (m / s), is shown in Table 4-6. Table 4: Minimum airflow 300m³ 3 At / h, the minimum wind speed at each measuring point corresponds to the following in Table 2: The average value was 0.26, the maximum value was 0.30 (13% less than 35% of the average), and the minimum value was 0.24 (9% less than 35% of the average). Table 5: Maximum airflow 1500m 3 At / h, the maximum wind speed at each measuring point corresponds to the following in Table 2: The average value is 0.95, the maximum value is 1.28 (35% difference from the average), and the minimum value is 0.65 (31% difference from the average, less than 35%). Table 6: Average airflow rate 800m³ 3 At / h, the average wind speed at each measuring point corresponds to the following in Table 2: The average value is 0.57, the maximum value is 0.72, which is 26% less than 35% of the average value, and the minimum value is 0.39, which is 32% less than 35% of the average value.

[0030] S3. Install the brake. Cooling air passes through the filter and enters the brake test chamber 2 through the ventilation duct. The inertial test bench drives the brake in the brake test chamber 2 to rotate, simulating the acceleration, cruising and braking deceleration process under real driving conditions of a car, generating wear particles, which are released into the cooling air. S4. The wear particles generated during the braking process form a uniform aerosol with the cooling air and are transported to the sampling plane 5 by the airflow. The particulate matter sampling and analysis device 3 collects particulate matter samples on the sampling plane 5, and analyzes and measures the particulate matter according to its category to obtain the measurement results. In this embodiment, the brake used in the test is a disc brake, and the ratio of its rated wheel load (Ln-f) to the mass of the brake disc (DM) is 54. According to the UN GTR-24 standard, for the case where 45 < Ln-f / DM < 65, the cooling flow rate should satisfy that the average brake temperature (ABT) of the brake ≥ 55 °C, the average initial brake temperature (IBT) is 75 °C ± 25 °C, and the average final brake temperature (FBT) is 115 °C ± 35 °C. First, set the initial value of the cooling air flow rate according to engineering experience. In the absence of a suitable reference, start the test with a flow rate of 950 m3 / h; then, heat the brake to (40 ± 1) °C according to the requirements of the UN GTR-24 standard, run a sub-cycle of the WLTP-brake (World Light-duty Test Procedure-Brake) cycle, and measure and record the brake temperature; if the brake temperature meets the aforementioned ABT, IBT, and FBT requirements, record the cooling air flow rate and use it for subsequent running-in and emission tests. In this test, when the cooling air flow rate is adjusted to 720 m 3 / h, it meets the above requirements for the brake disc temperature, so this flow rate is used for running-in and emission tests, that is, collecting particulate matter samples.

[0031] The specific implementation process is as follows: Using this solution, measure the right front axle brake equipped on a certain light vehicle, and obtain the Figure 8 test results as shown. The results of the PM2.5 emission factor, PM10 emission factor, TPN10 emission factor, and SPN10 emission factor are 0.50 mg / km, 0.60 mg / km, 6.16106×10 8 pieces / km, and 4.79815×10 8 pieces / km respectively.

[0032] Compared with the prior art, this solution has the following beneficial effects: By setting the cooling air conditioning system 1 and the inertia test bench 6, this solution realizes the uniform mixing of particulate matter and cooling air and simulates the kinetic energy of the vehicle during driving, thus more truly reflecting the emission characteristics of brake particles during the actual driving of the vehicle and improving the accuracy of the evaluation of brake wear particulate emissions; This solution adopts a fully enclosed brake particulate matter measurement system design, effectively avoiding the mixing of brake particulate matter with aerosols generated by other traffic and particulate matter in the external air, ensuring the accuracy and reliability of the test results; This solution optimizes the structure and control of the cooling air conditioning system 1, achieving precise control of the test environment temperature, humidity, and flow rate, thereby improving the test's adjustment accuracy and response speed. For the separation of complex dynamic states involving fluid-solid particle-thermodynamic coupling, this scheme verifies the consistency of wind speed by setting up a wind speed sensor to measure the inlet wind speed of the braking test chamber 2 in order to ensure the uniformity of aerosol mixing.

[0033] Example 2 This embodiment is basically the same as the above embodiment, except that it also includes a control system, which is used to receive environmental information collected by the monitoring unit 4 and control the operation of the inertial test bench 6 and the cooling air conditioning system 1.

[0034] Specifically, the control system includes a central processing unit, input devices, and output devices; The central processing unit controls the operation of the inertial test bench 6, the cooling air conditioning system 1, and the piping system; the input device is used to set test parameters; and the output device is used to display test data and environmental information. The control system adopts a modular design for easy maintenance and upgrades.

[0035] The sensor signal lines of the monitoring unit are connected to the control system via data lines, and digital signal processing is used for data acquisition and control, which facilitates the automatic and accurate regulation of the system.

[0036] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A flow-through brake particulate matter measurement system based on an inertial test bench method, characterized in that It includes: a cooling air conditioning system, an inertial test bench, and a braking test chamber; Cooling air conditioning system, used to provide the filtered air required for measurement; Brake test chamber, used to install different types of brakes; The braking test chamber is set on an inertial test bench, which is used to simulate the kinetic energy of a moving car, causing the brakes in the braking test chamber to rotate. The braking test chamber and the cooling air conditioning system are connected by pipes to form a measurement pipeline; a wind speed sensor is installed at the entrance of the braking test chamber to measure the wind speed at the entrance of the braking test chamber; The measuring pipeline is equipped with a monitoring unit and particulate matter sampling and analysis equipment; The monitoring unit is used to monitor and measure environmental information from the pipeline. Particulate matter sampling and analysis equipment is used to collect brake wear particles and sample gas from the measurement pipeline, and to analyze the quantity and quality of brake wear particles.

2. The flow-through brake particulate matter measurement system based on the inertia test bed method according to claim 1, characterized in that The air inlet of the brake test chamber is connected to the air outlet of the cooling air conditioning system through a pipe. Both the air outlet of the brake test chamber and the air inlet of the cooling air conditioning system are connected to pipes, forming an open measurement pipeline.

3. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 1, characterized in that... The air inlet and outlet of the braking test chamber are connected to the air outlet and air inlet of the cooling air conditioning system through pipes, forming a closed measurement pipeline.

4. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 2, characterized in that... The straight pipe connected to the air inlet of the brake test chamber is the first straight pipe, the straight pipe connected to the air outlet of the brake test chamber is the second straight pipe, and the straight pipe connected to the end of the second straight pipe that is not connected to the air outlet through the first bend is the third straight pipe; The air inlet of the cooling air conditioning system is connected to the fourth straight pipe, and the air outlet of the cooling air conditioning system is connected to the fifth straight pipe. The end of the fifth straight pipe that is not connected to the air outlet of the cooling air conditioning system is connected to the sixth straight pipe through the third bend. The end of the sixth straight pipe that is not connected to the third bend is connected to the end of the first straight pipe that is not connected to the air inlet of the brake test chamber through the fourth bend.

5. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 3, characterized in that... The straight pipe connected to the air inlet of the brake test chamber is the first straight pipe, the straight pipe connected to the air outlet of the brake test chamber is the second straight pipe, and the straight pipe connected at the end of the second straight pipe that is not connected to the air outlet via a first bend is the third straight pipe; the straight pipe connected at the end of the third straight pipe that is not connected to the first bend via a second bend is the fourth straight pipe, the end of the fourth straight pipe that is not connected to the second bend is connected to the air inlet of the cooling air conditioning system, the straight pipe connected to the air outlet of the cooling air conditioning system is the fifth straight pipe, the straight pipe connected at the end of the fifth straight pipe that is not connected to the air outlet of the cooling air conditioning system via a third bend is the sixth straight pipe, and the end of the sixth straight pipe that is not connected to the third bend is connected to the end of the first straight pipe that is not connected to the air inlet of the brake test chamber via a fourth bend.

6. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 4 or 5, characterized in that... The particulate matter sampling and analysis device is installed on the second right straight pipe, which is divided into a second left straight pipe and a second right straight pipe. The second right straight pipe is connected to the outlet of the braking test chamber, and the second left straight pipe is connected to the first bend pipe. The monitoring unit is installed on the third straight pipe, which is divided into the third upper straight pipe and the third lower straight pipe.

7. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 6, characterized in that... , the pipe dimensions are: L1≥2d i ; L2≥6d i ; L3≥2d i ; L4≥2d i ; L5≥5d i ; where L1 is the length of the first pipe, L2 is the length of the second right pipe, L3 is the length of the second left pipe, L4 is the length of the third upper pipe, L5 is the length of the third lower pipe, and d i is the diameter of the straight pipe.

8. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 1, characterized in that... The particulate matter sampling and analysis equipment includes a sampling probe, a sampling tube, and an analyzer; The sampling probe is installed on the sampling plane to collect brake wear particles; Sampling tubes are used to transport sample gas to analytical equipment; The analyzer is used to analyze the quantity and quality of brake wear particles. The sampling probes are installed on the pipe at a sampling plane. The sampling plane is a plane formed by the inlets of the four sampling probes (PM2.5, PM10, SPN10, and TPN10), which is perpendicular to the airflow direction. The sampling probes are arranged at the four corners of a square.

9. The flow-type braking particulate matter measurement system based on the inertial test bench method according to claim 1, characterized in that... The wind speed sensor is configured by setting a rectangular frame with a length and width greater than the diameter of the brake, and uniformly setting the wind speed values ​​at the center of each of the nine grids within the rectangular frame.

10. A method for measuring particulate matter in flowing braking systems based on an inertial test bench, characterized in that... The system employing the flow-type braking particulate matter measurement system based on the inertial test bench method as described in any one of claims 1-9 includes: S1. The cooling air conditioning system is activated, providing cooling air to the measuring pipeline that meets the preset temperature, preset humidity, and preset flow rate. The monitoring unit also monitors the environmental information of the measuring pipeline throughout the process. S2. Test the wind speed using a wind speed sensor, measure the wind speed value at the entrance of the braking test chamber, and determine if the wind speed is consistent. If yes, proceed to S3; otherwise, adjust the airflow using the cooling air conditioning system and then proceed to S2 again. S3. Install the brakes. Cooling air, after passing through the filter, enters the brake test chamber through the ventilation duct. The inertial test bench drives the brakes inside the test chamber to rotate, simulating the acceleration, cruising, and braking deceleration processes under real driving conditions, generating wear particles, which are released into the cooling air. S4. The wear particles generated during the braking process form a uniform aerosol with the cooling air and are transported to the sampling plane by the airflow. The particulate matter sampling and analysis equipment collects particulate matter samples on the sampling plane and analyzes and measures the particulate matter according to its category to obtain the measurement results.

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