Testing device and testing method for postprocessor temperature field calibration

Abstract

The invention provides a testing device and a testing method for postprocessor temperature field calibration, and belongs to the technical field of internal combustion engine postprocessing, and the method comprises the following steps: installing the testing device, fixing a plurality of thermocouple probes on a base, and enabling the end surfaces of the thermocouple probes to extend to a specified measurement area of a diesel particle filter; triggering and starting a regeneration process of the diesel particulate filter under a target working condition, and synchronously collecting temperature data from the thermocouple probe in real time; calculating the maximum temperature gradient in the diesel particulate filter based on the temperature data; and comparing the maximum temperature gradient with a preset safety threshold, and adjusting a regeneration control strategy according to a comparison result. According to the invention, the test efficiency, the data accuracy and the economical efficiency are obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aftertreatment of internal combustion engines, in particular to a testing device and method for calibrating temperature field of an aftertreatment device. BACKGROUND

[0002] Currently, DPF (Diesel Particulate Filter) regeneration technology has been widely applied in diesel engine aftertreatment systems. DPF regeneration is a PM (Particulate Matter) removal technology that is constantly improving with the development of high-temperature material technology, sensor technology and control algorithms. Its principle is to make the soot particles deposited in the DPF undergo oxidation reaction by raising the exhaust gas temperature or adding catalyst, thereby restoring the filtering performance of the DPF. With the increase of use time, the trapped particulate matter will clog the DPF carrier, causing the engine back pressure to rise, affecting the engine performance and fuel economy. Therefore, it is necessary to periodically remove the trapped particulate matter by high-temperature oxidation reaction through the "regeneration" process to restore the filtering performance of the DPF.

[0003] DPF regeneration strategies include active regeneration and passive regeneration and other ways, each of which has its advantages and disadvantages and applicable conditions, and selecting a suitable regeneration strategy needs to consider multiple factors such as engine operating conditions, emission levels, fuel economy, etc. The DPF regeneration process, especially active regeneration, involves complex high-temperature chemical reactions and thermal management, and the temperature control in the process is the key to determining the regeneration effect and the safety of the DPF carrier.

[0004] However, in the test, calibration and control strategy development of the regeneration process, the existing technical means faces the following severe challenges: the traditional DPF temperature field test method usually needs to drill holes on the DPF carrier to install contact type temperature sensors such as thermocouples. This destructive installation not only causes irreversible damage to the DPF sample, making it unable to be repeatedly used for subsequent verification tests, greatly increasing the research and development cost, but also may cause stress concentration at the hole, leading to cracks or even breakage of the carrier at high temperature regeneration. In addition, the test process involves frequent disassembly, installation and cooling of the DPF, the operation process is complicated, the preparation time for a single test can be as long as several hours, and the test efficiency is extremely low. At the same time, the synchronous monitoring of multiple parameters (such as temperature, pressure, NOx concentration) requires high technical level of the operator, further increasing the complexity and human error risk of the test. The selection and control of DPF regeneration strategy are highly dependent on accurate carbon load estimation and temperature field distribution. Currently, carbon load is mainly estimated by model, which is easily affected by fluctuations in engine original soot concentration, exhaust flow, oxygen concentration and other factors. Model estimation deviation will directly lead to improper regeneration timing - too early regeneration reduces fuel economy, and too late regeneration makes carbon load too high. Under high carbon load, the intense combustion of particulate matter will release a large amount of heat, which is easy to cause local temperature to be too high (hot spot) and huge maximum temperature gradient. If the control system cannot adjust the regeneration intensity (such as fuel injection amount) in real time and accurately, it will far exceed the thermal endurance limit of the DPF carrier material (and its catalytic coating), causing permanent damage such as carrier melting, sintering or cracking. The accuracy limitation of the sensor itself, the inconsistency of the installation position and the insertion depth, and the interference in the signal transmission process will all introduce significant measurement errors. The distortion of temperature field data directly affects the judgment of the real thermal state inside the DPF, making the control strategy calibrated based on this data have safety hazards in actual application. In addition, if the mathematical model and algorithm are not fully verified by high-precision experimental data, the calculation results will deviate from the physical reality, reducing the reliability of the entire control system. High-performance temperature control equipment, sensors, data acquisition systems, and frequent replacement of damaged DPF samples constitute high hardware and material costs. At the same time, the long test period, complex operation process and dependence on professionals result in huge human and time cost investment. These factors jointly restrict the rapid iteration development and optimization of the DPF aftertreatment system. SUMMARY

[0005] Therefore, it is necessary to provide a test device and test method for calibrating the temperature field of an aftertreatment device to solve the technical problems of low efficiency, inaccurate data and high cost in the prior art.

[0006] In order to solve the above technical problems, in a first aspect, the present application provides a test device for calibrating the temperature field of an aftertreatment device, comprising: a device body, an airflow channel being formed inside the device body, a plurality of groups of seats being uniformly arranged on the device body in a circumferential direction, a first connecting portion for mounting a thermocouple probe being arranged inside each seat; a first docking portion being arranged at an air inlet end of the device body, and a second docking portion being arranged at an air outlet end of the device body; the first docking portion being configured to dock with a first connecting member of a diesel particulate filter and to be locked by a first locking assembly; the second docking portion being configured to dock with a second connecting member of a downstream exhaust pipe of an engine and to be locked by a second locking assembly; wherein the test device is connected in series between the diesel particulate filter and the downstream exhaust pipe in a detachable manner through the first docking portion and the second docking portion.

[0007] In a possible implementation, at least one second connecting portion for connecting a pressure sensor and at least one third connecting portion for connecting a NOx sensor are further arranged on the device body.

[0008] In a possible implementation, a limiting structure is arranged in the first connecting portion, the limiting structure being used to limit an axial position of the thermocouple probe during installation, so as to ensure that insertion depths of all the thermocouple probes are consistent.

[0009] In a possible implementation, the limiting structure is an annular stepped surface formed on an inner wall of the threaded interface, the annular stepped surface being in abutment with an end surface of a connecting nut or a sealing bush of the thermocouple probe.

[0010] In a second aspect, the present application further provides a test method applied to the test device of the first aspect, the method comprising the following steps: installing the test device and fixing a plurality of thermocouple probes on the seats, end surfaces of the thermocouple probes extending to a designated measurement area of the diesel particulate filter; triggering a regeneration process of the diesel particulate filter under a target working condition, and synchronously collecting temperature data from the thermocouple probes in real time; calculating a maximum temperature gradient inside the diesel particulate filter based on the temperature data; comparing the maximum temperature gradient with a preset safety threshold, and adjusting a regeneration control strategy according to a comparison result.

[0011] In a possible implementation, the comparison of the maximum temperature gradient with the preset safety threshold and the adjustment of the regeneration control strategy according to a comparison result are as follows: if the maximum temperature gradient exceeds the preset safety threshold and a duration is less than a preset duration, a control parameter is lowered to reduce a regeneration rate. If the maximum temperature gradient exceeds the preset safety threshold and lasts for a time period greater than or equal to a preset time period, terminate the regeneration process.

[0012] In one possible implementation, the method further includes: acquiring exhaust pressure data and downstream NOx concentration data of the diesel particulate filter; calculating real-time carbon loading based on the exhaust pressure data and the downstream NOx concentration data; If the real-time carbon loading exceeds a carbon loading threshold, reducing the urea injection amount to reduce the regeneration rate.

[0013] In one possible implementation, the method further includes: If the downstream NOx concentration data is lower than a preset nitrogen oxide concentration threshold, increasing the urea injection amount; If the downstream NOx concentration data exceeds a preset nitrogen oxide concentration threshold, reducing the urea injection amount.

[0014] In one possible implementation, the method further includes: repeating triggering the regeneration process under different target operating conditions for testing, and generating a regeneration boundary mapping based on the test results; the target operating conditions include carbon loading and regeneration temperature, and the regeneration boundary mapping is used to define a safe regeneration operation boundary allowed by an engine control unit under the target operating conditions.

[0015] In one possible implementation, the method further includes: after triggering the regeneration process of the diesel particulate filter, controlling the engine to quickly switch from a current speed and torque to an idle state to simulate an extreme operating condition of sudden idle return in vehicle operation; updating the safe regeneration operation boundary according to the temperature data of the diesel particulate filter under the extreme operating condition.

[0016] The beneficial effects of the present application are: the test device for calibrating the temperature field of the after-treatment device provided by the present application has airflow channels inside the whole test device, standardized flanges (first / second docking parts) at both ends, and integrated bases in the circumferential direction. The test device is designed with the first docking part and the second docking part matching the standard flange interfaces of the DOC and the downstream exhaust pipe of the engine. In this way, when there is a test requirement, the original flange connection between the DPF inlet and the downstream exhaust pipe can be disconnected, the first docking part of the test device is aligned with the inlet flange of the DPF (i.e. the first connecting piece), and the second docking part of the test device is aligned with the flange of the downstream exhaust pipe (i.e. the second connecting piece). The two docking interfaces are locked by the first locking assembly and the second locking assembly respectively, so that the test device is connected to the engine after-treatment system as an independent external module, without any drilling, welding or structural modification of the expensive DPF, completely eliminating the irreversible damage to the sample caused by the installation of sensors in the traditional test method, so that the same DPF can be used for subsequent bench testing, vehicle verification and even final vehicle installation without damage, greatly reducing the research and development material cost. Further, the precise threaded base uniformly distributed in the circumferential direction and with uniform depth eliminates random errors caused by manual installation from a mechanical structure, ensuring that the spatial position of each test and each measurement point has high repeatability, providing a fundamental guarantee for accurately calculating the maximum temperature gradient and drawing reliable temperature field cloud maps. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 An embodiment structure schematic diagram of the test device for calibrating the temperature field of the after-treatment device provided by the present application is provided. Figure 2 Another embodiment structure schematic diagram of the test device for calibrating the temperature field of the after-treatment device provided by the present application is provided. Figure 3 An embodiment flow schematic diagram of the test method provided by the present application is provided. Figure 4 A temperature field distribution cloud diagram provided by the present application is provided. Figure 5 Another embodiment flow schematic diagram of the test method provided by the present application is provided. DETAILED DESCRIPTION

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0021] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] Before demonstrating the embodiments, the following terms will be explained.

[0024] DPF (Digital Fusion Filter): Its main function is to filter particulate matter (PM) from diesel engine exhaust. Diesel engines produce a large amount of particulate matter during combustion, primarily composed of soot, sulfates, and metal oxides. The DPF captures and stores these particles inside the filter through physical interception and diffusion deposition.

[0025] SCR: Its main function is to reduce nitrogen oxide (NOx) emissions from diesel engine exhaust. NOx is a general term for nitrogen oxides, mainly including nitric oxide (NO) and nitrogen dioxide (NO2). NOx is an important precursor to acid rain and photochemical smog, and is harmful to the environment and human health.

[0026] This invention provides a testing device and a testing method for temperature field calibration of a post-processor, which are described below.

[0027] Figure 1A schematic diagram of an embodiment of the test apparatus for post-processor temperature field calibration provided by the present invention is shown below. Figure 1 As shown, the testing apparatus includes: The device body 1 has an airflow channel inside. The device body 1 is uniformly provided with multiple sets of bases along the circumference. The base is provided with a first connecting part 4 for installing thermocouple probes. The device body 1 has a first docking part 2 at the air inlet end and a second docking part 3 at the air outlet end; The first docking part 2 is configured to dock with the first connector of the diesel particulate filter and be locked by the first locking assembly; The second docking part 3 is configured to dock with the second connector of the downstream exhaust pipe of the engine and lock it by the second locking assembly; The testing device is connected in series between the diesel particulate filter and the downstream exhaust pipe in a detachable manner through the first docking part 2 and the second docking part 3.

[0028] It should be noted that the device body 1 is preferably a hollow cylindrical structure, with its outer wall forming the airflow channel. The inner diameter and smoothness of this channel are optimized to ensure smooth exhaust airflow and minimize the impact on engine back pressure and flow field, thereby ensuring that the test conditions are close to real-world operating conditions. The device body 1 is made of high-temperature resistant stainless steel (such as 310S, 316L) or high-temperature nickel-based alloy to withstand the high-temperature exhaust gas (above 800°C) that may occur during DPF regeneration, and possesses good resistance to thermal fatigue and oxidation.

[0029] The device body 1 is provided with multiple sets of bases, and the structural details of the multiple sets of bases on the device body 1 for mounting thermocouples are as follows: Figure 2 As shown, multiple sets of bases are evenly distributed along the circumference of the circular device body 1. The number of bases is determined according to the size of the DPF and the measurement accuracy requirements. Preferably, the number of bases is 8, 10, or 12 sets to ensure that the temperature field distribution at the DPF inlet end face can be captured densely enough.

[0030] The first docking part 2 and the second docking part 3 are standardized flanges integrated into the air inlet and outlet ends of the device body 1. The mating surfaces, bolt hole spacing, and hole diameters of the first docking part 2 and the second docking part 3 are designed to fully match the DPF inlet flange and downstream exhaust pipe flange in the target engine aftertreatment system, and are respectively designed with flange structures that match the connecting parts of the diesel particulate filter and the downstream exhaust pipe. The first locking assembly and the second locking assembly are preferably V-type clamps. Each V-type clamp consists of two semi-circular clamps, a quick-locking lever (based on the principle of a cam or eccentric wheel), and a hinge shaft. The first docking part 2 and the second docking part 3 have multiple evenly distributed bolt holes. The test device is firmly connected between the DPF and the exhaust pipe through the first locking assembly (such as high-strength bolts and nuts) and the second locking assembly, ensuring that there will be no loosening or leakage during engine operation. At the same time, the sealing structure of the first docking part 2 and the second docking part 3 uses high-temperature resistant and corrosion-resistant gaskets to ensure airtightness. In actual operation, place the device body 1 between the DPF and the downstream pipeline, aligning its first mating part 2 with the first connector of the DPF (i.e., the DPF inlet flange) and its second mating part 3 with the second connector of the downstream pipeline (i.e., the downstream pipeline flange). Then, tighten these two mating points with V-clamps and turn the quick-locking lever to generate a huge radial locking force instantly, pressing and sealing both ends.

[0031] In summary, the testing device for after-treatment temperature field calibration provided by this invention has an internal airflow channel, standardized flanges at both ends (first / second mating parts 3), and an integrated base in the circumferential direction. The testing device is designed with a first mating part 2 and a second mating part 3 that match the standard flange interfaces of the DOC and the downstream exhaust pipe of the engine. In this way, when testing is required, the original flange connection between the DPF inlet and the downstream exhaust pipe can be disconnected, the first mating part 2 of the testing device can be aligned with the inlet flange of the DPF (i.e., the first connector), and the second mating part 3 of the testing device can be aligned with the flange of the downstream exhaust pipe (i.e., the second connector). The two mating interfaces are locked with the first locking component and the second locking component, respectively, allowing the testing device to be connected to the engine aftertreatment system as an independent external module. There is no need to drill, weld, or modify the expensive DPF at all, completely eliminating the irreversible damage to the sample caused by the installation of sensors in traditional testing methods. This allows the same DPF to be used without damage for subsequent bench testing, vehicle verification, and even final vehicle installation, significantly reducing the cost of R&D materials. Furthermore, the circumferentially uniform and depth-uniform precision threaded base eliminates random errors caused by human installation from a mechanical structure perspective, ensuring high repeatability of the spatial position of each test and each measuring point. This provides a fundamental guarantee for accurately calculating the maximum temperature gradient (ΔT / ΔL) and drawing reliable temperature field cloud maps.

[0032] In some embodiments of the present invention, such as Figure 1 As shown, the device body 1 is also provided with at least one second connection part for connecting a pressure sensor and at least one third connection part for connecting a NOx sensor.

[0033] It should be noted that one or more second connection parts are machined at a suitable location on the device body 1 (such as near the intake flange to accurately measure the airflow pressure entering the DPF). The second connection part is a pressure measurement port, typically a short pipe fitting welded or precision-machined onto the body wall, perpendicular to the axis of the device body 1. Its location is usually in the central region of the airflow channel to avoid interference from the wall boundary layer on the pressure measurement. The second connection part is usually a standard threaded interface (such as M10×1.0 or 1 / 8 NPT), allowing a high-frequency response pressure sensor to be directly screwed in. To adapt to the high-temperature exhaust environment, a capillary tube or cooler can be added between the sensor and the interface to protect the sensor core from high-temperature damage. The second connection part is used to monitor the exhaust pressure data at the DPF inlet in real time. Exhaust pressure data is a key parameter for calculating engine back pressure and assessing the degree of blockage caused by DPF carbon load.

[0034] One or more third connections are machined at a suitable location on the device body 1 (e.g., near the outlet flange for accurate measurement of downstream NOx concentration after DPF treatment). The third connection is a NOx sensor interface. Typically, it is a flange or sleeve larger than the pressure measurement port, welded to the device body 1 and located downstream of the airflow channel. The third connection is used to adapt to standard automotive or industrial NOx sensors. The NOx sensor is inserted radially or obliquely into the airflow channel through this flange, ensuring its sensitive element is exposed to the exhaust gas flow for accurate measurements. A high-temperature sealing ring is also used at the third connection to ensure airtightness. The third connection is used to measure the concentration of nitrogen oxides in the exhaust gas, i.e., the downstream NOx concentration, downstream of the DPF (or, in some designs, simultaneously upstream).

[0035] In this system, the cables for all sensors (thermocouples, pressure sensors, NOx sensors) are brought together and connected to a unified data acquisition and control unit. This unit is programmed to synchronously trigger and record data from all channels, ensuring that temperature, pressure, and NOx concentration are correlated at the same timestamp.

[0036] In this embodiment, a second connection part and a third connection part are provided on the device body 1, which realizes the synchronous measurement of multiple parameters such as temperature, pressure and NOx concentration, making the entire test system more compact and efficient, reducing the complexity of external connections and equipment, and allowing operators to acquire multiple important measurement data simultaneously in an integrated system, which facilitates comprehensive monitoring and analysis of the DPF regeneration process.

[0037] In some embodiments of the present invention, the first connecting part 4 is provided with a limiting structure, which is used to limit the axial position of the thermocouple probe during installation to ensure that the insertion depth of all the thermocouple probes is consistent.

[0038] It should be noted that the limiting structure is designed to create a reliable mechanical reference surface. When the thermocouple probe is installed in place, a part of it will make close contact with this reference surface, preventing further movement and achieving precise axial positioning. By using the limiting structure to define the axial position of all thermocouple probes during installation, the angle between the axis of each base and the axis of the main body, as well as the distance from the end face of each base to the front face of the DPF carrier, are strictly controlled and kept consistent. This ensures that the insertion depth of all thermocouple probes is consistent (e.g., a target depth of 10mm with an error controlled within ±1mm), which is crucial for achieving accurate temperature field mapping and gradient calculation.

[0039] In this embodiment, by setting a limiting structure within the first connecting portion 4, the insertion depth of all thermocouple probes is ensured to be consistent, thereby significantly improving the accuracy of temperature measurement. Due to the improved accuracy, the collected data is more reliable, reducing measurement errors caused by inconsistent insertion depths and further enhancing the reliability of the test results. Moreover, the use of the limiting structure simplifies the installation process of the thermocouple probes; operators do not need to perform complex measurements and adjustments, but simply insert the probes into the limiting structure, improving installation efficiency.

[0040] In some embodiments of the present invention, the limiting structure is an annular stepped surface formed on the inner circumference of the threaded interface, and the annular stepped surface abuts against the end face of the connecting nut or sealing bushing of the thermocouple probe.

[0041] It should be noted that the annular stepped surface is formed during a precision machining process when processing the first connecting part 4 (i.e., the precision thread inside the thermocouple base). Specifically, after tapping, a smooth annular plane, perfectly perpendicular to the thread axis, is cut at the bottom of the threaded hole using a tool at a specific angle. This plane is the annular stepped surface, which serves as the reference surface for the entire limiting structure. The end face of the connecting nut attached to the thermocouple probe, or the end face of a specially designed sealing bushing, abuts against the annular stepped surface.

[0042] The simplest solution is direct contact with the connecting nut. When the thermocouple probe is inserted into the base and tightened, the inner end face of the connecting nut (the plane near the hexagonal head of the nut) contacts the annular stepped surface at the bottom of the threaded hole. The tightening torque ensures that these two planes fit tightly, thus preventing the probe from penetrating further. A better solution is contact with the sealing bushing end face. A separate sealing bushing (usually made of high-temperature alloy or stainless steel) is fitted onto the thermocouple probe and then screwed into the base. One end of the bushing has an outer edge whose end face abuts against the annular stepped surface, while the other end may compress a flexible graphite ring, achieving both sealing and limiting functions.

[0043] In this embodiment, mechanical hard limiting ensures that the temperature measuring points of all thermocouples are located on the same precise measuring plane in front of the DPF inlet. Regardless of which operator, when, or how many times the test is repeated, as long as the thermocouples are tightened to the limiting surface, the position of all sensors is completely consistent with the first test. This completely eliminates the serious problems of inconsistent insertion depth and inability to compare data across batches caused by reliance on operator feel or experience in traditional methods, providing a stable and reliable experimental platform for research and development. Moreover, since the operator does not need to use a depth gauge for repeated measurement and adjustment during installation, nor does he need to worry about installation being too deep or too shallow, the entire installation process becomes as simple, fast, and reliable as tightening a screw. This limiting structure requires no additional parts (in the direct contact scheme) or only a simple bushing with multiple functions, making full use of the components of the threaded connection itself, achieving both fixed connection and precise positioning.

[0044] The testing device of this application is a detachable modular structure design. An improved external temperature sensor is connected through a transition ring (i.e., the first connecting part) to ensure uniform temperature distribution within the DPF. Multi-point temperature monitoring can be used to adjust the heating power or heat distribution in real time based on temperature feedback from different locations, thereby improving its high-temperature resistance and thermal stability.

[0045] The device body adopts a flange-type detachable structure, avoiding damage to DPF samples caused by welding or drilling, and enabling it to adapt to different models of DPF samples, thus improving the device's versatility and flexibility. It supports multiple batches of repeated experiments, improving equipment reuse rate and testing efficiency. The use of flange connections or snap-on fixing devices facilitates the replacement of DPF carriers of different specifications.

[0046] This application features a multi-hole integrated base design that monitors the three-dimensional temperature field distribution inside the DPF in real time. The non-contact or miniature embedded sensor design avoids damaging the sample structure, is compatible with standard thermocouple probes, and ensures consistent thermocouple probe insertion depth, thereby achieving precise mapping of the temperature field and improving the accuracy of temperature measurement.

[0047] Eight to ten thermocouple probes are screwed into the base, with the probe tips extending to a designated area at the front of the DPF carrier (distributed according to the carrier's honeycomb structure) to measure temperature data. Additionally, pressure and NOx sensors can be installed and connected. This allows for the measurement of not only temperature but also important parameters such as pressure and NOx concentration, providing more data support for comprehensive post-processing analysis. Multiple high-precision temperature sensors are placed at different key locations on the DPF carrier, including the inlet, outlet, central region, and near the wall. These sensors can accurately measure temperature changes inside the DPF in real time. The use of temperature sensors with high sensitivity and fast response ensures that data is captured instantaneously upon temperature changes, providing a reliable information foundation for subsequent precise control.

[0048] This application provides a detachable, multi-sensor integrated, non-destructive DPF temperature field testing device and method to improve testing efficiency, data accuracy, operational complexity, and economy.

[0049] Figure 3 This invention applies to the above. Figures 1 to 2 A schematic flowchart of an embodiment of the test method of the test apparatus shown is as follows: Figure 3 As shown, the test method includes the following steps: S100. Install the test device and fix multiple thermocouple probes on the base, with the end faces of the thermocouple probes extending to the designated measurement area of ​​the diesel particulate filter.

[0050] It should be noted that the designated measurement area specifically refers to the section of airflow channel in front of the DPF carrier inlet end and adjacent to the carrier. The tip of the probe extends precisely to this area to capture the temperature field of the airflow and reactant gas about to enter the DPF carrier, rather than the temperature inside the carrier.

[0051] Place the testing device at a suitable location between the diesel particulate filter and the downstream exhaust pipe. Then, sequentially install the thermocouple probes onto the first connecting part 4 of each set of bases, and adjust the length and angle of the probes so that the probe end face accurately extends into the designated measurement area inside the DPF. The designated measurement area can be divided according to the structure and regeneration principle of the DPF. For example, for a cylindrical DPF, test points 5 can be set at different positions along its axial and radial directions to comprehensively monitor the temperature distribution. Then, screw multiple (e.g., 8-10) standard thermocouple probes into the base of the device body 1, and use the annular stepped surface limiting structure inside the base to tighten all probes to the specified torque to ensure that their insertion depth is consistent.

[0052] After installing the thermocouple probes, the first mating part 2 of the test device is locked to the first connector of the DPF using the first locking assembly. Then, the second mating part 3 is locked to the second connector of the downstream exhaust pipe using the second locking assembly, completing the installation of the test device. After installing the thermocouples, the flange of the downstream exhaust pipe connected to the DPF outlet in the engine aftertreatment system is removed, exposing the DPF outlet flange. The intake flange (i.e., the first mating part 2) of the test device is aligned and pressed tightly against the outlet flange of the DPF. The outlet flange (i.e., the second mating part 3) of the test device is aligned and pressed tightly against the flange of the downstream exhaust pipe. Subsequently, the first locking assembly is used to lock and seal the first mating part 2 to the DPF outlet flange, and the second locking assembly is used to lock and seal the second mating part 3 to the downstream exhaust pipe flange, thereby detachably connecting the test device in series between the DPF and the downstream exhaust pipe. Alternatively, the test device can be connected in series between the DPF and the downstream exhaust pipe using the flanges and clamps at both ends. S200, under the target operating conditions, trigger the start of the regeneration process of the diesel particulate filter, and simultaneously collect temperature data from the thermocouple probe in real time.

[0053] It should be noted that the engine is operated under specific conditions that trigger DPF regeneration via an engine bench control system. This is typically achieved by increasing exhaust temperature, for example, through post-injection fuel (injecting a small amount of fuel during the later stages of the combustion stroke or the exhaust stroke), allowing the fuel to oxidize and release heat in the DOC, and by adjusting engine parameters (such as the throttle body and EGR valve) to increase exhaust temperature. Simultaneously with triggering regeneration, data acquisition is initiated, recording temperature data from all thermocouple channels at a high sampling rate (e.g., above 10Hz), and assigning a uniform timestamp to all temperature data.

[0054] S300. Calculate the maximum temperature gradient inside the diesel particulate filter based on the temperature data.

[0055] It should be noted that: based on the known spatial coordinates of the thermocouples on the measurement cross-section, the ratio of the temperature difference between adjacent or specific thermocouples to the spatial distance is calculated. Specifically, the temperature gradient between every two test points 5 is calculated using the formula ΔT / ΔL, where ΔT is the temperature difference between the two test points 5 (unit: °C), and ΔL is the spatial distance between the two test points 5 (unit: cm). The system calculates and tracks the maximum temperature gradient across the entire cross-section of the DPF in real time.

[0056] S400. Compare the maximum temperature gradient with a preset safety threshold, and adjust the regeneration control strategy according to the comparison result.

[0057] It should be noted that one or more safety thresholds (e.g., 50°C / cm) are preset. These preset safety thresholds are determined through prior limit calibration tests. The calculated maximum temperature gradient is compared with the preset safety threshold. If the maximum temperature gradient is less than the preset safety threshold, the regeneration process is safe, and the current regeneration control strategy (e.g., maintaining the current fuel injection quantity) is maintained. If the maximum temperature gradient is greater than or equal to the preset safety threshold, a control signal is immediately generated. The control signal is sent to the engine management system via the CAN bus or bench control system, enabling the engine management system to adjust the regeneration control strategy according to the control signal instructions.

[0058] In this embodiment, the testing device is placed at a suitable position between the diesel particulate filter and the downstream exhaust pipe. Then, thermocouple probes are sequentially installed onto the first connecting part 4 of each base group, and the length and angle of the probes are adjusted so that the probe end face accurately extends to the designated measurement area inside the DPF. The designated measurement area can be divided according to the structure and regeneration principle of the DPF. For example, for a cylindrical DPF, measurement points can be set at different positions along its axial and radial directions to comprehensively monitor the temperature distribution. After installation, the first docking part 2 of the testing device is locked to the first connecting piece of the DPF using the first locking assembly, and then the second docking part 3 is locked to the second connecting piece of the downstream exhaust pipe using the second locking assembly, completing the installation of the testing device. After installation, by accurately and in real-time monitoring the internal temperature distribution during the DPF regeneration process, problems of uneven temperature distribution can be detected in a timely manner, and the regeneration control strategy can be adjusted accordingly to avoid DPF damage caused by local overheating, thereby improving the regeneration effect and the service life of the DPF. Furthermore, by comparing the temperature gradient with a preset safety threshold, timely measures can be taken upon detecting any anomalies, effectively preventing safety accidents caused by excessive temperature and ensuring the safe operation of the engine system. This provides accurate data support for optimizing the regeneration control strategy, making the control strategy more scientific and reasonable. It can be dynamically adjusted according to different operating conditions and the actual state of the DPF, improving the efficiency and reliability of the regeneration process. Furthermore, the testing device adopts a detachable series connection method, making installation and disassembly convenient and quick, without causing excessive interference to the normal operation and maintenance of the engine. At the same time, the installation and replacement of thermocouple probes are also relatively simple, reducing maintenance costs and workload.

[0059] In some embodiments of the present invention, step S400 includes: If the maximum temperature gradient exceeds the preset safety threshold and the duration is less than the preset duration, the control parameters are lowered to reduce the regeneration rate. If the maximum temperature gradient exceeds the preset safety threshold and the duration is greater than or equal to the preset duration, the regeneration process is terminated.

[0060] It should be noted that multiple high-precision temperature sensors are placed at different locations inside the DPF (Diesel Particulate Filter). These sensors can measure the temperature distribution inside the DPF in real time. The temperature sensors should be placed in key locations such as the DPF inlet, outlet, central area, and near the walls to comprehensively monitor temperature changes. For example, 10 to 20 temperature sensors can be evenly arranged along the axial and radial directions of the DPF to ensure accurate capture of detailed changes in the temperature field. The temperature field distribution cloud map is shown below. Figure 4 As shown.

[0061] If the maximum temperature gradient exceeds a preset safety threshold and its duration is less than a preset duration (e.g., 30 seconds), the control unit will lower the control parameters of the regeneration process to reduce the regeneration rate. Specific measures may include: reducing fuel injection quantity, adjusting throttle opening, and extending regeneration time. Reducing fuel injection quantity lowers the combustion heat inside the DPF, thereby reducing the temperature gradient. Adjusting the throttle opening controls the airflow entering the DPF, reducing the combustion rate. Appropriately extending the regeneration time makes the temperature distribution inside the DPF more uniform, avoiding localized overheating.

[0062] If the maximum temperature gradient exceeds a preset safety threshold and lasts for a duration greater than or equal to a preset duration (e.g., 30 seconds), the control unit will terminate the regeneration process. Specific measures may include: cutting off the fuel injection system, issuing an alarm, and recording data. Immediately cutting off the fuel injection system stops the combustion process and prevents further temperature increases. The alarm system notifies operators to check the DPF status to ensure safety, and records relevant data for subsequent fault analysis and system optimization.

[0063] For example, the location and power of the heating source are precisely calculated and optimized. Based on factors such as the geometry of the DPF and airflow distribution, the optimal location and power allocation of each heating source are determined, and a temperature distribution cloud map of the DPF front end is plotted to calculate the maximum temperature gradient. If the maximum temperature gradient exceeds the limit, the fuel injection strategy is adjusted or regeneration is terminated to avoid carrier cracking. The temperature gradient limit is determined based on experimental results. Regeneration tests are conducted under different carbon loads to determine the limit carbon load. The temperature gradient is strongly correlated with both carbon load and fuel injection quantity during the regeneration process. The limit boundary can be determined through experiments and limited in subsequent calibration. The calibration principle is to feed the temperature gradient back to the CPU to control and reduce the fuel quantity. Adjustments to the fuel injection strategy can include adjusting the injection quantity, throttle opening, and proportional valve opening. When the maximum temperature gradient exceeds the limit, the regeneration fuel quantity is reduced to decrease the regeneration rate. The regeneration time is appropriately extended to ensure that the carrier temperature does not exceed the temperature gradient limit (i.e., the preset safety threshold).

[0064] For example, a testing device is installed, with 10 thermocouple probes inserted to a depth of 10 mm from the front end of the DPF carrier, simulating a carbon loading of 5 g / L. Regeneration is triggered, and the peak temperature (≤900℃) and maximum temperature gradient (ΔT / ΔL=45℃ / cm) are recorded. The carbon loading is gradually increased to 4 g / L. If the maximum temperature gradient exceeds the limit (preset safety threshold = 55℃ / cm), the maximum safe distance for testing carbon loading is determined to be 5 g / L.

[0065] In this embodiment, by monitoring the maximum temperature gradient in real time and adjusting the regeneration rate or terminating the regeneration process in a timely manner, local overheating inside the DPF can be effectively prevented. Local overheating may lead to excessive sintering or ablation of the DPF carrier material, or even cause safety accidents such as fires. For example, if the maximum temperature gradient is found to exceed the safety threshold during the regeneration process and the duration is short, reducing the regeneration rate can prevent further increases in local temperature, thereby protecting the safety of the DPF carrier. Furthermore, by strictly controlling the temperature gradient to not exceed the safety threshold, these situations can be effectively avoided, extending the service life of the DPF. For example, when the maximum temperature gradient exceeds the safety threshold and the duration is long, terminating the regeneration process in a timely manner can prevent the carrier from being damaged by prolonged exposure to high temperature gradients. Furthermore, by lowering the control parameters to reduce the regeneration rate, incomplete regeneration or local overheating caused by excessively high temperature gradients can be avoided while ensuring the regeneration effect. For example, if the maximum temperature gradient is found to be close to the safety threshold during the regeneration process, appropriately reducing the regeneration rate can make the temperature distribution inside the DPF more uniform, thereby improving the regeneration effect. Furthermore, by monitoring the maximum temperature gradient in real time and automatically adjusting the regeneration rate or terminating the regeneration process according to the preset control strategy, this automated control method reduces errors caused by human intervention and improves the reliability and stability of the system.

[0066] In some embodiments of the present invention, such as Figure 5 As shown, it also includes: S500: Obtain exhaust pressure data and downstream NOx concentration data flowing through the diesel particulate filter; S600. Calculate the real-time carbon loading based on the exhaust pressure data and the downstream NOx concentration data. S700. If the real-time carbon load exceeds the carbon load threshold, reduce the urea injection rate to decrease the regeneration rate.

[0067] It should be noted that: a high-precision pressure sensor should be installed upstream of the diesel particulate filter (DPF) to measure the exhaust pressure flowing through the DPF in real time. The pressure sensor should be installed near the DPF inlet to ensure the accuracy of the measurement data. A high-precision NOx sensor should be installed downstream of the DPF to measure the NOx concentration after DPF treatment in real time. The NOx sensor should be installed near the DPF outlet to accurately monitor the composition of the treated gas. A high-precision data acquisition system should be provided to simultaneously acquire data from the pressure and NOx sensors. The data acquisition system should have fast response and high precision, capable of acquiring data at millisecond intervals and converting it into digital signals for storage and processing. The data acquisition system should also have data preprocessing functions, such as filtering and noise reduction, to improve the accuracy and reliability of the data. A central control unit (such as a PLC or microcontroller) should be set up to receive the pressure and NOx concentration data transmitted from the data acquisition system and perform real-time analysis and processing according to a preset algorithm. The control unit can adjust the urea injection volume based on the analysis results to control the regeneration rate. A carbon loading calculation model should be established based on the exhaust pressure and downstream NOx concentration data. The model can be calculated based on the following formula: Real-time carbon loading = f(exhaust pressure, downstream NOx concentration).

[0068] Where f is a function derived from experimental data and theoretical analysis, and can be linear or nonlinear. For example, suppose the relationship between carbon loading and exhaust pressure and NOx concentration is: Real-time carbon loading = a × exhaust pressure + b × downstream NOx concentration + c.

[0069] Among them, a, b, and c are coefficients obtained through experimental calibration.

[0070] A preset carbon loading threshold, such as 5 g / L, is used to determine whether the real-time carbon loading exceeds the allowable range. The control unit receives carbon loading data in real time and compares it with the preset threshold. If the real-time carbon loading does not exceed the preset threshold, the current regeneration control strategy can continue. If the real-time carbon loading exceeds the preset threshold, the control unit will reduce the urea injection rate to decrease the regeneration rate. Specific measures may include reducing the urea injection rate by adjusting the injection frequency or injection time of the urea injection pump, thereby reducing the amount of urea injected and ensuring that the regeneration process is carried out within a safe range.

[0071] In this embodiment, by monitoring exhaust pressure and downstream NOx concentration in real time and calculating real-time carbon load based on this data, DPF overload can be effectively prevented. When the carbon load exceeds a preset threshold, the urea injection rate is promptly reduced to decrease the regeneration rate, preventing excessively high internal temperatures of the DPF and thus protecting the safety of the DPF carrier and extending its service life. Furthermore, by monitoring the carbon load in real time and adjusting the urea injection rate, precise control of the regeneration rate can be achieved. This not only ensures the regeneration effect but also avoids energy waste and excessive emissions caused by excessively high regeneration rates. Furthermore, by optimizing the regeneration strategy and reducing unnecessary urea injection, fuel consumption can be reduced and energy efficiency improved.

[0072] In some embodiments of the present invention, it further includes: If the downstream NOx concentration data is lower than the preset nitrogen oxide concentration threshold, the urea injection rate will be increased; If the downstream NOx concentration data exceeds the preset nitrogen oxide concentration threshold, the urea injection rate will be reduced.

[0073] It should be noted that by monitoring downstream NOx concentrations in real time and adjusting the urea injection rate, NOx emissions can be effectively prevented from exceeding standards. When the NOx concentration exceeds a preset threshold, the urea injection rate is promptly reduced to ensure that the NOx concentration remains within a reasonable range, thereby meeting environmental protection requirements. When the NOx concentration is below the preset threshold, the urea injection rate is increased to avoid excessive urea injection, reduce urea waste, and lower operating costs.

[0074] For example, an electrochemical sensor is installed at the NOx sensor interface (i.e., the third connection part) to synchronously collect NOx concentration data downstream of the DPF. Currently, carbon loading mainly relies on model estimation. Due to the lack of direct sensor measurement, it is difficult to predict changes in engine operating conditions in a timely manner, and accurate revision of carbon loading is challenging. By comparing the deviation between the measured NOx sensor value and the model estimate, it is possible to effectively determine whether the system is malfunctioning. During DPF regeneration, if urea injection is stopped, the catalytic efficiency of the SCR system and ammonia slip can be evaluated by comparing the NOx concentrations upstream and downstream of the DPF. If the downstream NOx concentration increases significantly, it indicates that nitrogen oxides are not fully reduced during regeneration. By collecting NOx concentration data under different carbon loading and temperature conditions, the correlation between the NOx formation model and the carbon loading model can be further calibrated, thereby establishing a carbon loading calculation method based on dynamic temperature changes. Based on the above data, the urea injection amount is dynamically adjusted to ensure that the NOx conversion efficiency is always not lower than 95%, while ensuring that the temperature gradient inside the DPF is always within a safe range, achieving synergistic optimization of emission control and carrier safety.

[0075] In this embodiment, precise control of the urea injection rate can be achieved by monitoring the NOx concentration in real time and adjusting the urea injection rate. This not only ensures that the NOx concentration remains within a reasonable range but also avoids energy waste and excessive emissions caused by excessive urea injection. Furthermore, by optimizing the urea injection strategy and reducing unnecessary urea injection, fuel consumption can be reduced and energy efficiency improved. For example, in the regeneration process, if the same NOx concentration control effect can be achieved by lowering the urea injection rate while avoiding NOx concentration exceeding the standard, then the urea injection rate can be reduced, thereby reducing energy waste.

[0076] In some embodiments of the present invention, it further includes: The regeneration process is repeatedly triggered under different target operating conditions for testing, and a regeneration boundary mapping map is generated based on the test results. The target operating conditions include carbon load and regeneration temperature, and the regeneration boundary mapping map is used to define the safe regeneration operation boundary allowed by the engine control unit under the target operating conditions.

[0077] It should be noted that different target operating conditions are determined, including different carbon loads and regeneration temperatures. For example, carbon loads can be set from 2 g / L to 6 g / L, and regeneration temperatures from 500°C to 700°C, to cover various operating conditions that the DPF may encounter in actual operation. Under each target operating condition, the DPF regeneration process is triggered. The control parameters of the regeneration process, such as fuel injection quantity and throttle opening, are adjusted by the control unit to achieve different carbon loads and regeneration temperatures. Under each target operating condition, real-time data on the temperature distribution, exhaust pressure, and NOx concentration inside the DPF are collected. The control unit analyzes the collected data to calculate key parameters such as the maximum temperature gradient and real-time carbon load.

[0078] Based on the test results, a regeneration boundary mapping map is generated. This map, using carbon loading and regeneration temperature as coordinate axes, defines the permissible safe regeneration operation boundaries under different target operating conditions. For example, the map can show that at a certain carbon loading, when the regeneration temperature exceeds a certain threshold, the maximum temperature gradient may exceed the safety threshold, thus defining the safe regeneration operation boundary.

[0079] In this embodiment, by generating a regeneration boundary mapping map, the safe regeneration operation boundaries allowed under different target operating conditions can be clearly defined, helping to prevent damage to the DPF during regeneration due to excessive temperature or carbon load. Furthermore, since the regeneration boundary mapping map provides the safe regeneration operation boundaries allowed under different target operating conditions, the engine control unit can subsequently precisely control the regeneration process based on these boundaries. This not only ensures the regeneration effect but also avoids energy waste and excessive emissions caused by excessive regeneration rates. Furthermore, real-time monitoring of the DPF's operating status and automatic adjustment of the regeneration process control parameters based on the regeneration boundary mapping map reduces human intervention errors and improves the system's reliability and stability.

[0080] For example, the thermocouples are arranged according to the specifications recommended by the DPF carrier manufacturer, and the following test methods are performed: (1) Carbon load accumulation stage: The engine is operated under specific conditions to accumulate carbon soot, and then the DPF is removed and weighed. The above process is repeated until the carbon load in the DPF reaches the target carbon load. During this process, the carbon load accumulation rate should be controlled to not be too fast. For example, the time required to reach a carbon load of 5 g / L should not be less than 2 hours. If the carbon load increases too slowly, the pre-injection amount can be appropriately increased, the EGR rate can be increased, or the boost pressure requirement can be reduced; if the increase is too fast, the opposite measures should be taken to adjust it.

[0081] (2) Regeneration Triggering and Data Acquisition Stage: Set the target regeneration temperature at the DPF inlet and select the engine speed and torque corresponding to the vehicle's driving condition of 120 km / h as the regeneration trigger conditions. When the DPF inlet temperature approaches the target regeneration temperature, quickly switch the engine to idle and record the highest temperature and maximum temperature gradient at each temperature measurement point. Continue the regeneration process for 20–30 minutes to thoroughly remove the carbon soot deposited in the DPF. After regeneration, the initial mass of the DPF needs to be remeasured to accurately calculate the actual carbon load (since the ash generated during the regeneration process cannot be completely removed, its influence must be eliminated by weighing).

[0082] (3) Extreme operating condition simulation and safety boundary confirmation: The above test was repeated at different idle speed switching points to simulate the extreme operating condition of the vehicle suddenly returning to idle speed (about 650 rpm) during active regeneration in harsh environments such as high altitude, high temperature and high humidity. Under this condition, the exhaust flow rate drops sharply and the heat dissipation capacity is weakened, while carbon soot combustion continues, which can easily lead to a sharp increase in the internal temperature and temperature gradient of the DPF, posing a risk of carrier burnout. By accurately measuring the internal temperature distribution of the DPF with thermocouples, the safe target regeneration temperature and carbon load range can be determined based on the temperature data, and the highest temperature and the maximum temperature gradient can be selected as the boundary calibration basis.

[0083] Repeat the above test steps under multiple different combinations of carbon loading and target regeneration temperature, and record the peak temperature, maximum temperature gradient, and other key parameters for each test. During testing, it is recommended to proceed from high-temperature conditions to low-temperature conditions sequentially. Based on the interim test results, the test range for controlling the target parameters and carbon loading can be further expanded if necessary to fully cover possible operating condition boundaries. Combine the material tolerance limits provided by the DPF carrier and coating manufacturers to determine the safe boundary conditions for the test, including: the maximum tolerance temperature of the DPF carrier is below 1050℃, the maximum instantaneous temperature of the coating does not exceed 950℃ (test limit value), and the temperature gradient does not exceed 500℃ / cm. Finally, based on the statistical results of the test data, determine the corresponding safe carbon loading range for each temperature; to address potential overshoot in actual DPF inlet temperature control, a safety margin of 30℃ should be reserved in the calibration results.

[0084] In some embodiments of the present invention, it further includes: After triggering the regeneration process of the diesel particulate filter, the engine is controlled to quickly switch from the current speed and torque to the idle state to simulate the extreme condition of the vehicle suddenly returning to idle during operation. The safety regeneration operation boundary is updated based on the temperature data of the diesel particulate filter under the extreme operating conditions.

[0085] It should be noted that on the test bench, the engine is operated under high exhaust flow conditions (e.g., corresponding to a vehicle speed and torque of 120 km / h), and DPF regeneration is triggered under these conditions, causing the internal temperature of the DPF to rise and enter a stable combustion state. A rapid return to idle is then performed; that is, when the regeneration process enters a critical stage (e.g., carbon soot is undergoing severe oxidation and the temperature reaches its peak), the control unit issues a command to instantly release the throttle and switch the engine control target to idle speed (e.g., 650 rpm). This switching process should be completed within 1-3 seconds to simulate the extreme condition of a sudden return to idle speed during vehicle operation. Under this extreme condition, the peak value and spatial distribution of the internal temperature of the DPF are accurately captured using the aforementioned multi-thermocouple array, and the maximum peak temperature and maximum temperature gradient under this worst-case scenario are calculated. If the calculated peak temperature and gradient still do not exceed the material safety limits in this extreme test, it indicates that the current test combination (carbon loading, regeneration temperature) is very safe, and its safety boundary can be maintained or even appropriately relaxed. If the test data exceeds the safety limits, it proves that even though the combination is safe in normal steady-state testing, it poses a risk of burning out the DPF in real, dynamic driving environments. Therefore, the safety boundary is tightened to a more conservative level to ensure that the regeneration process is safe even in the event of sudden idling.

[0086] The above provides a detailed description of the testing device and method for post-processor temperature field calibration provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A testing device for temperature field calibration of a post-processor, characterized in that, include: The device body has an airflow channel inside, and multiple sets of bases are evenly arranged around the circumference of the device body. The bases are provided with a first connecting part for installing thermocouple probes. The device body has a first docking part at the air inlet end and a second docking part at the air outlet end. The first docking portion is configured to dock with the first connector of the diesel particulate filter and be locked by the first locking assembly; The second docking part is configured to dock with the second connector of the downstream exhaust pipe of the engine and lock it in place by the second locking assembly; The testing device is connected in series between the diesel particulate filter and the downstream exhaust pipe in a detachable manner through the first docking part and the second docking part.

2. The testing apparatus according to claim 1, characterized in that, The device body is also provided with at least one second connection part for connecting a pressure sensor and at least one third connection part for connecting a NOx sensor.

3. The testing apparatus according to claim 1, characterized in that, The first connecting part is provided with a limiting structure, which is used to limit the axial position of the thermocouple probe during installation to ensure that the insertion depth of all the thermocouple probes is consistent.

4. The testing apparatus according to claim 3, characterized in that, The limiting structure is an annular stepped surface formed on the inner circumference of the threaded interface, and the annular stepped surface abuts against the end face of the connecting nut or sealing bushing of the thermocouple probe.

5. A test method applied to the test apparatus according to any one of claims 1 to 4, characterized in that, Includes the following steps: Install the test device and fix multiple thermocouple probes to the base, with the end faces of the thermocouple probes extending to the designated measurement area of ​​the diesel particulate filter; The regeneration process of the diesel particulate filter is triggered under the target operating conditions, and temperature data from the thermocouple probe is collected in real time simultaneously. The maximum temperature gradient inside the diesel particulate filter is calculated based on the temperature data. The maximum temperature gradient is compared with a preset safety threshold, and the regeneration control strategy is adjusted based on the comparison result.

6. The test method according to claim 5, characterized in that, The maximum temperature gradient is compared with a preset temperature threshold, and the regeneration control strategy is adjusted based on the comparison result. If the maximum temperature gradient exceeds the preset safety threshold and the duration is less than the preset duration, the control parameters are lowered to reduce the regeneration rate. If the maximum temperature gradient exceeds the preset safety threshold and the duration is greater than or equal to the preset duration, the regeneration process is terminated.

7. The test method according to claim 5, characterized in that, Also includes: Acquire exhaust pressure data and downstream NOx concentration data flowing through the diesel particulate filter; The real-time carbon loading is calculated based on the exhaust pressure data and the downstream NOx concentration data. If the real-time carbon load exceeds the carbon load threshold, the urea injection rate is reduced to decrease the regeneration rate.

8. The test method according to claim 7, characterized in that, Also includes: If the downstream NOx concentration data is lower than the preset nitrogen oxide concentration threshold, the urea injection rate will be increased; If the downstream NOx concentration data exceeds the preset nitrogen oxide concentration threshold, the urea injection rate will be reduced.

9. The test method according to claim 5, characterized in that, Also includes: The regeneration process is repeatedly triggered under different target operating conditions for testing, and a regeneration boundary mapping map is generated based on the test results. The target operating conditions include carbon load and regeneration temperature, and the regeneration boundary mapping map is used to define the safe regeneration operation boundary allowed by the engine control unit under the target operating conditions.

10. The test method according to claim 8, characterized in that, Also includes: After triggering the regeneration process of the diesel particulate filter, the engine is controlled to quickly switch from the current speed and torque to the idle state to simulate the extreme condition of the vehicle suddenly returning to idle during operation. The safety regeneration operation boundary is updated based on the temperature data of the diesel particulate filter under the extreme operating conditions.

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