An automatic test system and method for vehicle brake system HCU fluid circuit performance

Abstract

The application belongs to the technical field of brake system performance testing, and relates to an automatic testing system and method for HCU liquid path performance of a vehicle brake system. The system is arranged in a fully-closed safety cabinet, and comprises an upper computer, a servo cylinder pressure building, HCU control, dynamic cooling and a programmable load simulation unit. The system is cooperatively controlled through a CAN bus to realize accurate cooperation of pressure building, pressure maintenance, pressure reduction and valve body driving. The dynamic cooling system adjusts air cooling parameters according to load and time length to ensure stable coil temperature rise. The programmable load unit simulates working condition load by combining multiple steel cylinders. The testing method comprises the steps of preparation, parameter configuration, automatic exhaust, automatic testing, safety monitoring and report generation. Data is collected at high frequency throughout the process, and a PDF report with diagnostic suggestions is automatically analyzed and generated for archiving and storage in a three-level structure. The application realizes full-process automation, has high testing precision, high safety and traceable data, and can efficiently complete HCU liquid path performance detection.

Description

Technical Field

[0001] This invention belongs to the field of vehicle braking system performance testing technology, specifically relating to an automatic testing system and method for the HCU hydraulic circuit performance of a vehicle braking system. Background Technology

[0002] With the widespread application of automotive hydraulic control systems, the performance testing requirements for HCUs are increasing. Traditional testing platforms are mostly semi-open structures that rely on manual operation, which presents the following problems:

[0003] 1. Low testing efficiency and insufficient automation: manual replacement of pipelines and manual control of pressure and valve body operation are required, resulting in poor test consistency;

[0004] 2. Lack of efficient cooling methods: The valve body coil uses natural cooling or simple air cooling, resulting in unstable temperature rise during continuous testing, which affects the test accuracy;

[0005] 3. Poor safety: Hydraulic pipelines and electrical equipment are mostly open or semi-closed, posing safety hazards;

[0006] 4. Inflexible load simulation: Using actual vehicle calipers or fixed loads, it is impossible to simulate the pressure characteristics under different working conditions;

[0007] 5. Data processing relies on manual labor: Test data is scattered, and reports need to be manually organized, which is inefficient and prone to errors.

[0008] Although existing HCU hydraulic system testing benches can perform multi-channel pressure testing, they still have the aforementioned shortcomings and cannot achieve fully automated testing and intelligent report generation. There is an urgent need for an efficient, accurate, and safe HCU hydraulic circuit performance testing device. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic testing system and method for the hydraulic circuit performance of a vehicle braking system (HCU).

[0010] To achieve the objectives of this invention, the following technical solutions will be adopted.

[0011] An automated testing system for the hydraulic circuit performance of a vehicle braking system's hydraulic control unit (HCU) is housed in a fully enclosed safety cabinet comprising dedicated fixtures, coil fixtures, and a safety relay system; including:

[0012] The HCU under test is mounted in a dedicated fixture and connected to the HCU control unit via an aviation quick-connect plug; wherein: the coil fixture includes a coil frame with a gas path network, a dynamic cooling system integrated on the coil frame to provide high-pressure cooling gas to the gas path network, and the HCU control unit;

[0013] The host computer control unit, developed based on LabVIEW, communicates with the servo electric cylinder pressure-building unit, HCU control unit, and programmable load simulation unit via CAN bus. It controls the servo electric cylinder pressure-building unit to perform pressure-building, pressure-holding, and pressure-reducing operations, while simultaneously controlling the HCU control unit to drive the valve body coils and motors of each tested HCU according to a preset duty cycle and timing sequence. It also controls the programmable load simulation unit to simulate dynamic load characteristics under different braking conditions and collect data. Furthermore, it connects to the safety relay system via an I / O serial port to monitor and verify the safety door of the fully enclosed safety cabinet and send power-off signals to the HCU control unit. A test report is generated upon completion of the test.

[0014] The servo electric cylinder pressure building unit has built-in pressure and displacement sensors. It is connected to the programmable load simulation unit through hydraulic lines and performs pressure building, pressure holding and pressure reduction operations through dual closed-loop control of pressure and displacement.

[0015] The HCU control unit includes an ECU controller, a temperature sensor, and a current sensor. The ECU controller controls the HCU valve body coil and motor under test to operate according to a preset duty cycle and timing sequence. In conjunction with the servo electric cylinder pressure building unit, it performs pressure building, pressure holding, and pressure reduction operations to energize each HCU valve body coil under test, so that each HCU valve body under test is in an open or closed state.

[0016] The dynamic cooling system cools the coil of each tested HCU valve body through the gas network. The pressure of the high-pressure cooling gas and the cooling time are dynamically adjusted by the host computer control unit according to the current load and duration of the test item.

[0017] The programmable load simulation unit uses a combination of multiple cylinders to simulate different wheel cylinder loads. The upper computer control unit independently controls the solenoid valve of each cylinder to simulate the dynamic load characteristics under different braking conditions.

[0018] Furthermore, the host computer control unit also includes an anomaly monitoring module, which constructs a real-time system status profile by scanning data streams from temperature, current, pressure, and displacement sensors.

[0019] Furthermore, each tested HCU valve body coil is integrated onto the coil frame via a coil mounting slot, and the air circuit network can directly act on the side and back of each tested HCU valve body coil.

[0020] Furthermore, the tested HCU valve body coil includes a booster valve coil, a pressure limiting valve coil, a pressure reducing valve coil, and a suction valve coil. The booster valve coil and the pressure limiting valve coil both have a rated parameter of 12V / 3A, and their opening degree is controlled by the host computer control unit via PWM within a duty cycle range of 0-100%. The pressure reducing valve coil and the suction valve coil both have a rated parameter of 12V / 3A, and their opening degree is switched between 0% and 100% by the host computer control unit. The motor has a rated parameter of 12V / 30A, and its speed is adjusted by the host computer control unit via PWM within a duty cycle range of 0-100%.

[0021] Furthermore, the safety relay system is used to monitor and verify the locking status of all safety door locks in the fully enclosed safety cabinet in real time.

[0022] The method for testing the HCU fluid circuit performance using the aforementioned automated testing system includes the following steps:

[0023] S61. Test preparation: Connect the HCU under test to the HCU control unit via an aviation quick-connect plug, configure the cylinder load combination of the programmable load simulation unit, close the safety door of the fully enclosed safety cabinet, and unlock the parameter setting permission after verifying the safety door locking status through the safety relay system.

[0024] S62. Parameter Configuration and Identity Binding: Select the target test item through the host computer control unit, set the test parameters, including the cooling pressure of the dynamic air cooling system, cooling time, servo electric cylinder pressure build-up rate, and number of test repetitions. Scan the QR code of the HCU under test to complete the unique binding of test data and product identity.

[0025] S63, Automated Exhaust: The host computer control unit starts the automated exhaust process, sequentially executing the high-pressure blowing to purge the pipeline, vacuum pumping to establish a negative pressure environment, and servo electric cylinder reciprocating pressure building to assist exhaust, so as to completely remove the residual gas in the pipeline.

[0026] S64. Test Execution: The host computer control unit sends control commands through the CAN bus to control the servo electric cylinder pressure building unit to build up pressure to the target pressure according to the preset mode and maintain it stably. At the same time, it controls the ECU controller to drive the coil and motor of each tested HCU valve body to act according to the preset duty cycle and timing. The dynamic air cooling system dynamically adjusts the pressure and cooling time of the high-pressure cooling gas according to the current load and duration. The hydraulic circuit pressure, coil drive voltage and current data are collected at high frequency throughout the process.

[0027] S65. Safety monitoring and fault handling: During the test, the pressure, current and equipment status are monitored in real time. If an abnormal pressure rise or current overload fault is detected, an emergency stop command is immediately triggered to stop the servo cylinder, cut off the power and release the pressure.

[0028] S66. Data Processing and Report Generation: After the test is completed, the host computer control unit automatically parses the collected TDMS format data, calculates the pressure build-up rate and leakage rate characteristic values, plots performance curves and marks key points, generates a PDF test report with diagnostic suggestions, and archives the data according to a three-level classification storage structure of product model-production batch-individual product.

[0029] Furthermore, the first level of the three-level classification storage structure is the product model level, where independent data storage directories are established according to different HCU models; the second level is the production batch level, where subdirectories are divided according to production batches under the same model directory; and the third level is the individual product level, where independent data folders are established under the same batch directory using the product serial number as a unique identifier.

[0030] Furthermore, the high-pressure blowing time is 3-8 seconds, the target vacuum degree of vacuum pumping is ≤-0.09MPa, and the number of times the servo electric cylinder reciprocates to build up pressure is 2-5 times.

[0031] Furthermore, the pressure build-up rate of the servo electric cylinder is adjustable within the range of 0.1-5MPa / s, the stable holding time is 5-30s, and the data acquisition frequency is not less than 1kHz.

[0032] Furthermore, the cooling pressure of the dynamic air cooling system is adjusted within the range of 0.3-1.0 MPa, and the ratio of cooling time to test duration is 1:2-1:5.

[0033] Furthermore, the diagnostic suggestions are generated based on a preset fault knowledge base, including abnormal data feature matching and troubleshooting direction prompts corresponding to sealing ring leakage, valve core jamming, and abnormal coil resistance.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Fully automated process: From parameter setting to report generation, no manual intervention is required, significantly improving testing efficiency and data consistency;

[0036] 2. High testing accuracy: Dual-mode control of servo electric cylinder and fine PWM drive achieve millimeter-level accuracy and millisecond-level response;

[0037] 3. High stability: The dynamic cooling system ensures controllable coil temperature rise and guarantees data repeatability during long-term continuous testing;

[0038] 4. High safety: The fully enclosed structure and safety interlock design achieve physical isolation between humans and machines, eliminating potential safety hazards;

[0039] 5. Good versatility: quick replacement of aviation plugs and programmable load simulation, adaptable to different HCU models and test conditions;

[0040] 6. Convenient data traceability: Three-level classification storage is bound to product identity, supporting quality traceability and statistical analysis. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the architecture of the testing system described in this invention;

[0042] Figure 2 This is a schematic diagram of the dynamic cooling system structure described in this invention;

[0043] Figure 3 This is a flowchart of the automated testing and report generation process described in this invention. Detailed Implementation

[0044] As an embodiment of the present invention, such as Figure 1 As shown, an automatic testing system for the hydraulic circuit performance of a vehicle braking system (HCU) is housed in a fully enclosed safety cabinet comprising dedicated fixtures, coil fixtures, and a safety relay system; including:

[0045] The HCU under test is mounted in a dedicated fixture and connected to the HCU control unit via an aviation quick-connect connector. The coil fixture includes a coil frame with a gas path network, a dynamic cooling system integrated into the coil frame to provide high-pressure cooling gas to the gas path network, and the HCU control unit.

[0046] The aviation quick-connect plug uses an M12 waterproof aviation plug (12 pins), of which 4 pins are used for coil power supply (2mm² wire diameter), 2 pins are used for temperature sensor (shielded wire), and 2 pins are used for CAN_H / CAN_L (twisted pair shielded); the plug and tooling connection is equipped with a foolproof positioning pin to ensure the uniqueness of the wiring.

[0047] Coil fixture: Made of 6061-T6 aluminum alloy, the positioning surface is hard anodized, and the whole is a rectangular aluminum frame; Positioning mechanism: It has 4 sets of positioning grooves corresponding to the HCU valve body coil under test. The grooves are embedded with silicone thermal pads (thickness 3mm, thermal conductivity ≥3W / m·K). After the coil is installed, the back is tightly attached to the aluminum frame, and the side is exposed to the airflow of the jet hole;

[0048] The host computer control unit, developed based on LabVIEW, communicates with the servo electric cylinder pressure-building unit, HCU control unit, and programmable load simulation unit via CAN bus. It controls the servo electric cylinder pressure-building unit to perform pressure-building, pressure-holding, and pressure-reducing operations, while simultaneously controlling the HCU control unit to drive the valve body coils and motors of each tested HCU according to a preset duty cycle and timing sequence. It also controls the programmable load simulation unit to simulate dynamic load characteristics under different braking conditions and collect data. Furthermore, it connects to the safety relay system via an I / O serial port to monitor and verify the safety door of the fully enclosed safety cabinet and send power-off signals to the HCU control unit. A test report is generated upon completion of the test.

[0049] The servo electric cylinder pressure-building unit, with built-in pressure and displacement sensors, is connected to the programmable load simulation unit via hydraulic lines. It performs pressure-building, pressure-holding, and pressure-reducing operations through dual closed-loop control of pressure and displacement. The servo electric cylinder uses a T-slot cast iron base, rigidly connected to the frame of a fully enclosed safety cabinet via four sets of M16 high-strength bolts, with an installation flatness ≤0.05mm / m. The output end of the servo electric cylinder is connected to the piston rod of the hydraulic master cylinder via a floating coupling, with a floating amount of ±0.5mm to eliminate radial off-center load and ensure that the coaxiality between the HCU master cylinder interface and the servo electric cylinder output end is ≤0.05mm. A ball screw-type servo electric cylinder (5mm lead) is used to convert rotary motion into linear motion, achieving closed-loop control in conjunction with a magnetic grating displacement sensor.

[0050] The HCU control unit includes an ECU controller, a temperature sensor, and a current sensor. The ECU controller controls the HCU valve body coil and motor under test to operate according to a preset duty cycle and timing sequence. In conjunction with the servo electric cylinder pressure building unit, it performs pressure building, pressure holding, and pressure reduction operations to energize each HCU valve body coil under test, so that each HCU valve body under test is in an open or closed state.

[0051] The dynamic cooling system uses high-pressure cooling gas to directly act on the sides and back of each tested HCU valve body coil through the gas path network. The pressure and cooling time of the high-pressure cooling gas are dynamically adjusted by the host computer control unit according to the current load and duration of the test item.

[0052] The programmable load simulation unit uses a combination of multiple cylinders to simulate different wheel cylinder loads. The upper computer control unit independently controls the solenoid valve of each cylinder to simulate the dynamic load characteristics under different braking conditions.

[0053] As an embodiment of the present invention, the servo electric cylinder pressure-building unit is equipped with pressure and displacement sensors to achieve closed-loop control of the pressure-building process, with a response accuracy down to the millisecond level. Specifically: the pressure sensor is a strain gauge sensor with an accuracy class of 0.25%FS (full-scale error ≤ ±0.25%), a range of 0-20MPa, and a sampling frequency ≥2kHz, used for real-time acquisition of hydraulic circuit pressure; the displacement sensor is a magnetic scale with a resolution of 1μm and a stroke accuracy of ±0.01mm, used for closed-loop position control of the servo electric cylinder;

[0054] As an embodiment of the present invention, the host computer control unit further includes an anomaly monitoring module. The anomaly monitoring module constructs a real-time system status profile by scanning data streams from temperature, current, pressure, and displacement sensors. Specifically, the temperature sensor is attached to the coil frame, uses a PT100 platinum resistance thermometer with an accuracy of ±0.5℃, and is used to monitor the coil temperature rise and feed it back to the dynamic cooling system.

[0055] As an embodiment of the present invention, the fully enclosed safety cabinet is welded from 2mm cold-rolled steel plate, with an 8mm thick explosion-proof tempered glass observation window on the front, and an overall protection level of IP54; a dual-circuit hard-wired system is formed by a safety relay and a door magnetic switch, the door magnetic switch is normally closed, and the response time is ≤10ms; the safety relay is connected in series to the emergency stop terminal and the programmable power enable terminal of the servo cylinder driver to form a hardware-level emergency stop circuit independent of software control; a leakage collection tank with a volume of ≥50L is set at the bottom of the cabinet, and a liquid level sensor is configured to automatically trigger a shutdown alarm when the hydraulic oil leakage exceeds 5L.

[0056] As an embodiment of the present invention, the structural details and key parameter ranges of the gas path network are as follows:

[0057] Structural details: The aluminum frame (300mm×200mm×80mm) has an annular air chamber with a cross-sectional size of 10mm×8mm. Four 6mm diameter branch copper pipes lead to the mounting positions of the pressure boosting valve, pressure limiting valve, pressure reducing valve, and suction valve respectively. Each HCU valve body coil mounting position under test has six 1.2mm diameter air jet holes, four of which are aligned with the side of the coil and two are aligned with the back of the coil, forming a directional cooling airflow to ensure that forced convection heat dissipation evenly covers the coil surface.

[0058] Key parameter range: Cooling medium: dry compressed air or nitrogen, gas source pressure 0.6-1.0MPa, working pressure adjustment range after filter and pressure reducing valve is 0.3-0.8MPa; Flow control: each coil branch is equipped with a mass flow sensor (range 0-50L / min, accuracy ±2%FS), and the stepless flow rate adjustment is achieved from 0-30L / min through a proportional valve; Dynamic cooling strategy: the ratio of cooling time to test duration is set to 1:3; when the coil temperature exceeds 80℃, the forced cooling mode is automatically triggered, and gas is continuously supplied until the temperature drops below 60℃.

[0059] As an embodiment of the present invention, the tested HCU valve body coil includes a booster valve coil, a pressure limiting valve coil, a pressure reducing valve coil, and a suction valve coil, wherein:

[0060] Both the booster valve coil and the pressure relief valve coil have a rated value of 12V / 3A, and the host computer controls the opening degree of any valve within the duty cycle range of 0-100% via PWM.

[0061] Both the pressure reducing valve coil and the suction valve coil are rated at 12V / 3A, and are controlled by the host computer to switch between two discrete opening states of 0% or 100%.

[0062] The motor has a rated voltage of 12V / 30A and its speed can be adjusted arbitrarily within the duty cycle range of 0-100% by the host computer via PWM.

[0063] As an embodiment of the present invention, the method for testing the HCU fluid circuit performance using the aforementioned automatic testing system includes the following steps:

[0064] S1. Test preparation: Connect the HCU under test to the HCU control unit via an aviation quick-connect plug, configure the cylinder load combination of the programmable load simulation unit, close the safety door of the fully enclosed safety cabinet, and unlock the parameter setting permission after verifying the safety door locking status through the safety relay system.

[0065] S2. Parameter Configuration and Identity Binding: The target test item is selected via the host computer control unit, and test parameters are set. These parameters include the cooling pressure of the dynamic air-cooling system, cooling time, servo electric cylinder pressure build-up rate, and number of test repetitions. The QR code of the HCU under test is scanned to uniquely bind the test data to the product identity. The binding mechanism is as follows:

[0066] QR code parsing: Using an industrial barcode scanner with an RS232 interface, the QR code (DM code or QR code) of the tested HCU product is parsed. The QR code contains 26 characters of information: product model (8-bit ASCII) + production batch (6-digit date + 2-digit serial number) + serial number (10-digit serial number).

[0067] Software implementation: The host computer LabVIEW program integrates the NI Vision QR code recognition module, which automatically fills the parsed data into the test configuration cluster and serves as the basis for generating the file path, thus achieving a unique binding between test data and product identity.

[0068] S3. Automated Exhaust: The host computer control unit initiates the automated exhaust process, sequentially executing high-pressure air blowing to purge the pipeline, vacuum pumping to establish a negative pressure environment, and servo electric cylinder reciprocating pressure building to assist exhaust, thoroughly removing residual gas from the pipeline; the specific steps are as follows:

[0069] S31: The host computer control unit controls the relay module via RS232 to open the high-pressure pneumatic ball valve (diameter DN8), with an air source pressure of 0.6MPa, a purging time set to 5s, and an airflow velocity ≥15m / s;

[0070] S32: Start the vacuum pump (pumping speed ≥40L / min), monitor the vacuum gauge (Pirani vacuum gauge) through the IO module, and maintain the vacuum level of the pipeline for 10s when it reaches -0.095MPa to desorb dissolved gas;

[0071] S33: The servo electric cylinder reciprocates at a rate of 0.5MPa / s 3 times, with a stroke of 50mm. It uses oil compression-expansion to drive air bubbles to the wheel cylinder cylinder. Finally, it opens the wheel cylinder exhaust valve for 2 seconds to completely expel the residual gas.

[0072] S4. Test execution: The host computer control unit sends control commands through the CAN bus to control the servo electric cylinder pressure building unit to build up pressure to the target pressure according to the preset mode and maintain it stably. At the same time, it controls the ECU controller to drive the coil and motor of each tested HCU valve body to act according to the preset duty cycle and timing. The dynamic air cooling system dynamically adjusts the pressure and cooling time of the high-pressure cooling gas according to the current load and duration. The hydraulic circuit pressure, coil drive voltage and current data are collected at high frequency throughout the process.

[0073] S5. Safety monitoring and fault handling: During the test, the pressure, current and equipment status are monitored in real time. If an abnormal pressure rise or current overload fault is detected, an emergency stop command is immediately triggered to stop the servo cylinder, cut off the power and release the pressure.

[0074] Security protection timing logic:

[0075] Monitoring cycle: The system scans the data streams from temperature, pressure, displacement, and current sensors at a cycle of 10ms;

[0076] Emergency stop triggering conditions: pressure change rate > 5MPa / ms (abnormal pressure surge) or coil current > 3.5A (current overload);

[0077] Emergency stop sequence: After an anomaly is detected, the following actions shall be completed within 50ms:

[0078] An emergency stop command is sent to the servo electric cylinder via CAN to perform rapid braking (deceleration ≥ 5 m / s²).

[0079] The programmable power supply (12V / 30A) output is cut off via I / O;

[0080] Open the pressure relief valve (normally closed solenoid valve, opens when energized) to reduce the pipeline pressure to below 0.1 MPa within 3 seconds.

[0081] S6. Data Processing and Report Generation: After the test is completed, the host computer control unit automatically parses the collected TDMS format data, calculates the pressure build-up rate and leakage rate characteristic values, plots performance curves and marks key points, generates a PDF test report with diagnostic suggestions, and archives the data according to a three-level classification storage structure of product model-production batch-individual product.

[0082] As an embodiment of the present invention, the purging time of the high-pressure blowing is 3-8s, the target vacuum degree of the vacuum pump is ≤-0.09MPa, and the number of times the servo electric cylinder reciprocates to build up pressure is 2-5 times.

[0083] As an embodiment of the present invention, the pressure build-up rate of the servo electric cylinder is adjustable in the range of 0.1-5MPa / s, the stable holding time is 5-30s, and the data acquisition frequency is not less than 1kHz.

[0084] As an embodiment of the present invention, the cooling pressure adjustment range of the dynamic air cooling unit is 0.3-1.0 MPa, and the ratio of cooling time to test duration is 1:2-1:5.

[0085] As an embodiment of the present invention, the diagnostic suggestions are generated based on a preset fault knowledge base, including abnormal data feature matching and troubleshooting direction prompts corresponding to sealing ring leakage, valve core jamming, and abnormal coil resistance.

[0086] As an embodiment of the present invention, the front of the fully enclosed safety cabinet is equipped with an acrylic observation window with a safety interlock. All high-pressure hydraulic lines, air lines, electrical control units, and the HCU under test are all built inside the fully enclosed safety cabinet. During the testing process, the equipment safety relay ensures that all protective doors are locked before the test program can be started, fundamentally eliminating the safety hazards of open testing platforms. The safety structure design of the fully enclosed safety cabinet is as follows:

[0087] The cabinet frame is made of 2mm cold-rolled steel plate welded together, with an 8mm thick explosion-proof tempered glass observation window on the front, and an overall protection level of IP54.

[0088] Safety interlock: A dual-circuit hard-wired system is formed by a safety relay and a door magnetic switch. The door magnetic switch is normally closed and has a response time of ≤10ms. The safety relay is connected in series to the emergency stop terminal and the programmable power enable terminal of the servo cylinder driver to form a hardware-level emergency stop circuit independent of software control.

[0089] Leakage protection: A leakage collection tank with a volume of ≥50L is installed at the bottom of the cabinet and equipped with a liquid level sensor. When the hydraulic oil leakage exceeds 5L, a shutdown alarm will be automatically triggered.

[0090] The system uses a servo electric cylinder as a high-precision pressure source and communicates with the host computer in real time via a CAN bus. It supports closed-loop control in both pressure and displacement modes and is equipped with high-precision pressure and displacement sensors, achieving millimeter-level accuracy and millisecond-level response in the pressure build-up process, which significantly improves the accuracy of pressure control and data acquisition.

[0091] In terms of load simulation, the system employs programmable cylinder banks to achieve high-fidelity load simulation. Each simulated wheel cylinder load consists of two small-capacity cylinders and one large-capacity cylinder, with each cylinder controlled independently by a solenoid valve for flexible on / off switching. All cylinders undergo PV characteristic curve calibration using specialized equipment, enabling precise simulation of dynamic load characteristics under different braking conditions. Combined with the precise control of the servo electric cylinder, high-precision performance verification of the HCU under all operating conditions, including pressurization, pressure holding, and depressurization, can be achieved. Cylinder calibration requirements include:

[0092] Volume calibration: Each cylinder is calibrated using the standard volume method (water volume method), with a volume accuracy error of ≤±0.5%. The calibration data is engraved on the bottom of the cylinder in the form of a QR code.

[0093] PV characteristic calibration: Using nitrogen as the medium, 10 pressure points were uniformly selected within the range of 0-18MPa, and the pressure-volume correspondence was recorded. The least squares method was used to fit the PV characteristic curve, and the coefficient of determination R² of the fitted curve was ≥0.999.

[0094] Load simulation accuracy: Each cylinder is controlled by an independent solenoid valve with a response time of ≤15ms. Combined with calibration curves, high-fidelity simulation of wheel cylinder load under different braking conditions is achieved.

[0095] To address the issue of coil heating affecting test consistency during testing, the system integrates a highly efficient dynamic cooling system. All control valve coils are integrated and mounted within an aluminum alloy frame with internal air channels. During testing, high-pressure cooling gas flows through the air channel network within the frame, directly acting on the sides and back of each coil to achieve efficient and uniform forced convection cooling. The host computer can dynamically adjust the on-time and waiting interval of the cooling airflow according to the current load and duration of different test items, ensuring that the coils are always within the optimal operating temperature range. This guarantees the stability and data repeatability of long-term, high-load continuous testing. Figure 2 As shown.

[0096] As an embodiment of the present invention, before testing, the operator scans the QR code of the HCU product under test using a barcode scanner. The host computer automatically parses and obtains basic information such as product model, serial number, and production batch, completing the unique binding of test data with product identity. Based on the product information obtained from the barcode scan, the system establishes a three-level classification storage mechanism: the first level is the product model level, establishing independent data storage directories according to different HCU models; the second level is the production batch level, dividing the same model directory into subdirectories according to production batches; the third level is the individual product level, establishing independent data folders under the same batch directory using the product serial number as a unique identifier. All raw data files, process parameter records, and test result reports generated during the testing process are automatically archived and stored on the local disk and network storage (NAS) according to the above three-level classification structure, realizing orderly management and efficient traceability of test data. Among them: Three-level classification storage:

[0097] Level 1 (Product Model Level): Create a folder named after the product model (e.g., "HCU_ABS_V2.1"), and embed the standard test parameter XML configuration file for that model.

[0098] Second level (production batch level): Create a batch subfolder under the first level directory, named in the format "YYYYMMDD_XX" (e.g., "20260115_03").

[0099] Level 3 (Individual Product Level): Create an independent folder named after the serial number in the batch directory (e.g., "SN_202601150001") to store the original TDMS data file (naming rule: model_serial number_test item_timestamp.tdms), PDF test report, and test log file;

[0100] Data synchronization: By calling the Robocopy command through LabVIEW's System Exec VI, real-time mirror backup of the local disk and NAS (Network Attached Storage) is achieved, ensuring dual redundant data storage.

[0101] This system uses LabVIEW as its core host computer control platform, achieving fully automated operation from test initiation to report generation. Before testing, operators only need to input the product model, serial number, and preset test parameters (such as cooling wait time for each function and number of repeated tests) into the human-machine interface to start the test process with one click. During testing, the host computer precisely controls the servo electric cylinder to perform pressure build-up, pressure holding, and pressure release operations via the CAN bus, and simultaneously controls the ECU controller to drive the HCU solenoid valves to operate according to preset duty cycles.

[0102] The system performs high-frequency real-time monitoring and acquisition of hydraulic circuit pressure, coil drive voltage, and current throughout the entire process. All data is synchronously stored in TDMS standard format to local and network storage (NAS). When abnormal pressure surges, current overloads, or other fault signs are detected, the system will automatically trigger a safety protection sequence: immediately stop the electric cylinder operation, cut off the programmable power output, and control the corresponding valves to depressurize the pipeline, ensuring the safety of equipment and products.

[0103] After testing, the system automatically enters the intelligent report generation phase. The LabVIEW program calls the stored TDMS data file and automatically completes data parsing, characteristic value calculation (such as pressure build-up rate, leakage rate, response time, etc.), and performance curve plotting. The report generation module automatically identifies key test points and tolerance ranges in the curve graph and clearly presents all calculation results in a structured table format. Furthermore, based on preset algorithms and rule bases, the system can perform preliminary analysis and diagnosis of abnormal data points, providing possible causes of problems in the final PDF test report, greatly assisting subsequent troubleshooting. All raw data and reports are automatically archived and backed up to a designated storage path, achieving traceability of the testing process and standardized data management. Figure 3 As shown.

[0104] The principle of dynamic air cooling ensuring controllable temperature rise: In existing technologies, coil temperature rise leads to changes in resistance, which in turn causes the drive current to drift, resulting in deviations in valve core opening control. This invention rapidly conducts heat from the back of the coil to the frame body through a coil frame (aluminum alloy thermal conductivity ≥150W / m·K); simultaneously, high-pressure gas (0.3-0.8MPa) is directly injected onto the sides and back of the coil, forming forced convection cooling (convective heat transfer coefficient ≥200W / (m²·K)), which is more than 20 times more efficient than natural cooling (heat transfer coefficient approximately 10W / (m²·K)). Actual measurements show that after 20 consecutive pressurization tests (each coil energized for 5 seconds), the coil temperature stabilized at 75±5℃, and the current fluctuation was <±1%, thus ensuring the repeatability of the test data (Cpk≥1.33).

[0105] The principle behind the improved pressure build-up accuracy of servo electric cylinders: Traditional hydraulic systems use proportional valves and accumulators for pressure build-up, which suffers from hydraulic compressibility hysteresis and valve core dead zone nonlinearity. This invention uses a servo electric cylinder to directly drive the master cylinder piston, converting rotary motion into linear motion (5mm lead) via a ball screw. Combined with a 1μm resolution magnetic grating displacement sensor and a 0.25%FS pressure sensor, a pressure-displacement dual closed-loop control is formed. The electric cylinder response time (from command to reaching 90% of the target pressure) is ≤50ms, with a pressure control accuracy of ±0.05MPa. Compared to traditional hydraulic systems (response time 200-500ms, accuracy ±0.2MPa), the response speed is improved by 4-10 times, and the accuracy by 4 times. This allows for precise capture of pressure jumps at the moment the HCU valve body opens (detecting pressure changes at the 10ms level).

[0106] The principle behind the three-tiered storage system for convenient traceability is as follows: QR code scanning uniquely binds product identity (model-batch-serial number) to test data, avoiding manual data entry errors (human entry error rate is approximately 0.5%, while QR code recognition error rate is <0.001%). The three-tiered directory structure (model / batch / individual unit) and file naming rules (including timestamps) ensure centralized storage of data throughout the entire product lifecycle. Traceability query time is reduced from 10-30 minutes of traditional manual searching to within 10 seconds (direct location via file path), supporting quality traceability and statistical analysis.

[0107] As an embodiment of the present invention, taking the HCU valve body sealing performance test of ABS as an example, the method for testing the HCU hydraulic circuit performance using the aforementioned automatic testing system is as follows:

[0108] In the fully automated testing process for ABS HCUs, the operator experience is designed to be highly integrated, safe, and intelligent, embodying the core design philosophy of "one-click start, full monitoring, and automatic decision-making." The entire process begins with rapid hardware preparation. The operator first precisely installs the ABS-HCU under test onto a dedicated fixture and quickly connects it to the corresponding integrated coil cooling fixture via an aviation quick-connect interface. This design significantly improves the efficiency and consistency of product replacement. Subsequently, based on the load simulation requirements of this test, the operator adjusts the activation status of the corresponding cylinder through the control panel on the side of the equipment, flexibly configuring the load characteristics of the wheel cylinder to simulate different operating conditions from no-load to full-load. After completing the load setting, the heavy safety door on the front of the equipment is closed, and the system enters the standby state.

[0109] The operator moves to the console and first triggers the "safety door lock" instruction in the upper computer software interface developed by LabVIEW. The upper computer verifies the physical status of all door locks in real time through a safety relay and unlocks the parameter setting interface only after receiving the feedback signal that all door locks have been reliably locked. This hardware and software interlock mechanism fundamentally eliminates the risk of personnel intervention during equipment operation and prioritizes safety.

[0110] In the parameter setting interface, the operator checks the test items to be executed this time from the preset test library, such as valve body sealability test, pressurization rate test, decompression characteristic test, etc., and sets detailed execution parameters for each test item, including the number of repeated tests and the dynamic cooling parameters configured for the estimated heat generation of the coil for this test item, such as cooling air flow pressure and intermittent cooling duration. This parameterized setting system makes the test process both standardized and customizable. For example, the specific parameters for the valve body sealability test: pressure build-up rate 0.5 MPa / s, target pressure 15 MPa, pressure holding time 30 s; leakage rate judgment criterion: a pressure drop ≤ 0.3 MPa / 30 s (i.e., leakage rate ≤ 0.01 MPa / s) is considered qualified; cooling parameters: since the coil does not generate heat during the pressure holding stage, the cooling time is set to 0 s, and only pre-cooled for 2 s before pressure build-up.

[0111] After confirming all parameters, the operator clicks the "start test" button, and the system enters the full-automatic operation mode. At the same time, the multi-dimensional abnormal monitoring system of the upper computer is started synchronously, continuously scanning the data streams from various sensors such as temperature, pressure, displacement, current, etc., to construct a real-time system health status profile. The first step of the test is automated pipeline cleaning and preparation. The upper computer controls the relay through the serial port to open the high-pressure pneumatic ball valve, and a strong air flow quickly purges the entire hydraulic pipeline, thoroughly removing any possible residual oil, laying a foundation for establishing a pure oil circuit environment. After the purging is completed, the high-pressure air valve closes.

[0112] Immediately afterwards, the system starts the second step - vacuum oil injection. The upper computer controls the vacuum pump to operate, pumping the inside of the pipeline to a high vacuum state. After reaching the preset vacuum degree threshold, the system automatically opens the precision ball valve of the oil supply system, and under the action of the pressure difference, the clean hydraulic oil quickly and smoothly fills the entire pipeline. This process effectively avoids the problem of air bubbles easily generated by traditional oil injection methods. Then it enters the third step, auxiliary exhaust and system pre-tightening. The upper computer sends instructions to the servo electric cylinder through the CAN bus to make it perform several reciprocating pressure build-up movements in a specific mode, using the compressibility of the oil to drive and gather any possible trace gases remaining in the pipeline to the wheel cylinder simulator, and finally, by controlling the instantaneous opening of the exhaust valve at the wheel cylinder end, these residual gases are completely discharged from the system. After these three automated preparation steps, the system has reached a highly consistent initial test state and is ready.

[0113] The core testing phase then proceeds according to a pre-set sequence. For each test item, the host computer acts as the overall commander, precisely and synchronously controlling the servo electric cylinder to establish the target pressure or stroke. Simultaneously, it drives the ECU via CAN commands, causing the ABS coil to operate according to a specific duty cycle and timing sequence. Throughout the entire process, the intelligent air-cooling system integrated within the coil fixture remains operational. Its unique feature is that cooling is not constant but dynamically adjusted based on the attributes of the currently executed test item (such as long operation time or high heat generation) and preset cooling parameters. For example, after a high-energy-consumption boost test, the system automatically extends the cooling time and increases the airflow pressure to ensure the coil temperature quickly returns to its optimal operating range, thus guaranteeing the accuracy of the next test data is not affected by temperature drift.

[0114] After all preset test items are successfully completed, the system does not stop working but enters the intelligent post-processing stage. The host computer automatically calls all time-series data files generated in this test and starts the embedded data analysis engine. The engine not only calculates key performance indicators and plots characteristic curves such as pressure-time and current-pressure, but also has preliminary diagnostic intelligence. It automatically compares the test results with preset pass / fail thresholds and generates a clear "pass / fail" conclusion. For any data points that exceed the standard, the analysis engine will perform pattern matching based on the fault knowledge base. In the test report, it not only marks the anomaly but also lists several of the most common causes that may lead to the anomaly, such as "seal leakage," "valve core jamming," or "abnormal coil resistance," providing strong directional guidance for the operator's subsequent troubleshooting. Diagnostic suggestion generation parameters: The system performs pattern matching on abnormal data based on the preset fault knowledge base.

[0115] If the leakage rate exceeds the standard (>0.01MPa / s), the test report will indicate the troubleshooting direction for "seal ring leakage";

[0116] If the pressure build-up rate is abnormal (more than 20% below the set value), the "valve core stuck" error message will be displayed, indicating the troubleshooting direction.

[0117] If the current waveform is distorted (harmonic content > 15%), it indicates "abnormal coil resistance" and the troubleshooting direction.

[0118] After the report is generated, for ease of maintenance and environmental cleanliness, the system will perform a final automated cleanup after operator confirmation. The host computer will restart the high-pressure blowing program to blow the test oil in the pipeline back to the waste oil collection device, ensuring that there is no oil leakage at the pipeline and interface when disassembling ABS products, and maintaining a clean working environment. Thus, a complete closed-loop testing process, from installation, setup, testing, analysis to cleanup, is automatically completed by the system. The operator's core role shifts from repetitive manual operation to process supervision and decision-making confirmation, achieving a comprehensive improvement in testing efficiency, data quality, and personnel safety.

[0119] As an embodiment of the present invention, a timing control mechanism for the operation of the electric cylinder and the valve body.

[0120] The testing system of this invention establishes a precise timing control mechanism for different test items, with the electric cylinder action and coil action executed collaboratively according to a preset timing sequence. Taking pump capacity testing as an example, the specific parameter configuration is as follows: Product identity binding: QR code parsing is "HCU_ABS_V2.1_20260115_SN202601150001";

[0121] Dynamic cooling parameters: The cooling gas pressure is adjusted to 0.6MPa, and the ratio of cooling time to test duration is set to 1:3 to ensure that the coil temperature does not exceed 80℃;

[0122] Servo electric cylinder pressure build-up parameters: pressure build-up rate set to 1.0 MPa / s, target pressure 3 MPa, and stable holding time 10 s;

[0123] Data acquisition parameters: Sampling frequency set to 2kHz, recording duration 20s;

[0124] Coil drive parameters: pressure booster valve duty cycle 80%, motor speed 50%, duration 5s;

[0125] Number of test repetitions: Set to 3 times, and take the average as the final result;

[0126] Pass / fail threshold: Pressure rise time ≤ 5s (from 0 to 8MPa) is considered pass / fail.

[0127] Its automated exhaust timing logic:

[0128] Step S1 (High-pressure air blowing): The host computer controls the relay module via RS232 to open the high-pressure pneumatic ball valve (diameter DN8), with an air source pressure of 0.6MPa, a blowing time of 5s, and an airflow velocity of ≥15m / s;

[0129] Step S2 (vacuum pumping): Start the vacuum pump (pumping speed ≥40L / min), monitor the vacuum gauge (Pirani vacuum gauge) through the IO module, and maintain the vacuum level of the pipeline for 10 seconds when it reaches -0.095MPa to desorb dissolved gas;

[0130] Step S3 (Auxiliary Exhaust): The servo electric cylinder reciprocates at a rate of 0.5MPa / s 3 times, with a stroke of 50mm, using oil compression-expansion to drive air bubbles to the wheel cylinder cylinder. Finally, the wheel cylinder exhaust valve is opened for 2s to completely expel the residual gas.

[0131] Its timing control flow is as follows:

[0132] At time T0: The host computer control unit sends a command via CAN to open the main cylinder pneumatic ball valve, close the wheel cylinder pneumatic ball valve, and establish the hydraulic circuit of the main cylinder-pressure reducing valve-pressure boosting valve;

[0133] T0+100ms: The ECU controller sends a 100% duty cycle command (fully open) to the pressure reducing valve coil for 500ms.

[0134] T0+600ms: The servo electric cylinder starts to build up pressure, builds up to 3MPa at a rate of 1.0MPa / s, and maintains it stably for 10s;

[0135] T0+10600ms: Close the pneumatic ball valve of the main cylinder and cut off the hydraulic circuit of the main cylinder;

[0136] T0+10700ms: Send an 80% duty cycle command to the booster valve coil and a 50% speed command to the motor, lasting for 5 seconds;

[0137] T0+15700ms: Acquire pressure sensor data (acquisition frequency 2kHz) to determine whether the pressure rises from 0 to ≥8MPa within 5s to evaluate pump capacity.

[0138] Its security protection timing logic:

[0139] Monitoring cycle: The system scans the data streams from temperature, pressure, displacement, and current sensors at a cycle of 10ms;

[0140] Emergency stop triggering conditions: pressure change rate > 5MPa / ms (abnormal pressure surge) or coil current > 3.5A (current overload);

[0141] Emergency stop sequence: After an anomaly is detected, the following actions shall be completed within 50ms:

[0142] An emergency stop command is sent to the servo electric cylinder via CAN to perform rapid braking (deceleration ≥ 5 m / s²).

[0143] The programmable power supply (12V / 30A) output is cut off via I / O;

[0144] Open the pressure relief valve (normally closed solenoid valve, opens when energized) to reduce the pipeline pressure to below 0.1 MPa within 3 seconds.

[0145] After the test is completed, the host computer uses the pressure data collected by the pressure sensor to determine whether the pressure has risen to a specified threshold position within a specified time, thereby evaluating the pump's performance. Different test items can be configured with different timing parameters according to their technical characteristics, enabling flexible customization of the test process.

[0146] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. An automatic testing system for the hydraulic circuit performance of a vehicle braking system's hydraulic control unit (HCU), characterized in that: The automated testing system is housed in a fully enclosed safety cabinet containing dedicated fixed fixtures, coil fixtures, and a safety relay system; including: The HCU under test is mounted in a dedicated fixture and connected to the HCU control unit via an aviation quick-connect plug; wherein: the coil fixture includes a coil frame with a gas path network, a dynamic cooling system integrated on the coil frame to provide high-pressure cooling gas to the gas path network, and the HCU control unit; The host computer control unit, developed based on LabVIEW, communicates with the servo electric cylinder pressure-building unit, HCU control unit, and programmable load simulation unit via CAN bus. It controls the servo electric cylinder pressure-building unit to perform pressure-building, pressure-holding, and pressure-reducing operations, while simultaneously controlling the HCU control unit to drive the valve body coils and motors of each tested HCU according to a preset duty cycle and timing sequence. It also controls the programmable load simulation unit to simulate dynamic load characteristics under different braking conditions and collect data. Furthermore, it connects to the safety relay system via an I / O serial port to monitor and verify the safety door of the fully enclosed safety cabinet and send power-off signals to the HCU control unit. A test report is generated upon completion of the test. The servo electric cylinder pressure building unit has built-in pressure and displacement sensors. It is connected to the programmable load simulation unit through hydraulic lines and performs pressure building, pressure holding and pressure reduction operations through dual closed-loop control of pressure and displacement. The HCU control unit includes an ECU controller, a temperature sensor, and a current sensor. The ECU controller controls the HCU valve body coil and motor under test to operate according to a preset duty cycle and timing sequence. In conjunction with the servo electric cylinder pressure building unit, it performs pressure building, pressure holding, and pressure reduction operations to energize each HCU valve body coil under test, so that each HCU valve body under test is in an open or closed state. The dynamic cooling system cools the coil of each tested HCU valve body through the gas network. The pressure of the high-pressure cooling gas and the cooling time are dynamically adjusted by the host computer control unit according to the current load and duration of the test item. The programmable load simulation unit uses a combination of multiple cylinders to simulate different wheel cylinder loads. The upper computer control unit independently controls the solenoid valve of each cylinder to simulate the dynamic load characteristics under different braking conditions.

2. The automatic testing system for the hydraulic circuit performance of a vehicle braking system HCU according to claim 1, characterized in that: The host computer control unit also includes an anomaly monitoring module, which constructs a real-time system status profile by scanning data streams from temperature, current, pressure, and displacement sensors.

3. The automatic testing system for the hydraulic circuit performance of a vehicle braking system HCU according to claim 1, characterized in that: Each tested HCU valve body coil is integrated onto the coil frame via a coil mounting slot, and the air circuit network can directly act on the side and back of each tested HCU valve body coil.

4. The automatic testing system for the hydraulic circuit performance of a vehicle braking system HCU according to claim 3, characterized in that: The tested HCU valve body coils include a booster valve coil, a pressure limiting valve coil, a pressure reducing valve coil, and a suction valve coil. The booster valve coil and the pressure limiting valve coil are both rated at 12V / 3A, and their opening degree is controlled by the host computer control unit via PWM within a duty cycle range of 0-100%. The pressure reducing valve coil and the suction valve coil are both rated at 12V / 3A, and their opening degree is switched between 0% and 100% by the host computer control unit. The motor is rated at 12V / 30A, and its speed is adjusted by the host computer control unit via PWM within a duty cycle range of 0-100%.

5. An automatic testing system for the hydraulic circuit performance of a vehicle braking system HCU according to claim 1, characterized in that: The safety relay system is used to monitor and verify the locking status of all safety door locks in the fully enclosed safety cabinet in real time.

6. A method for testing the performance of the HCU fluid circuit using the automatic testing system according to any one of claims 1-5, characterized in that: Includes the following steps: S61. Test preparation: Connect the HCU under test to the HCU control unit via an aviation quick-connect plug, configure the cylinder load combination of the programmable load simulation unit, close the safety door of the fully enclosed safety cabinet, and unlock the parameter setting permission after verifying the safety door locking status through the safety relay system. S62. Parameter Configuration and Identity Binding: Select the target test item through the host computer control unit, set the test parameters, including the cooling pressure of the dynamic air cooling system, cooling time, servo electric cylinder pressure build-up rate, and number of test repetitions. Scan the QR code of the HCU under test to complete the unique binding of test data and product identity. S63, Automated Exhaust: The host computer control unit starts the automated exhaust process, sequentially executing the high-pressure blowing to purge the pipeline, vacuum pumping to establish a negative pressure environment, and servo electric cylinder reciprocating pressure building to assist exhaust, so as to completely remove the residual gas in the pipeline. S64. Test Execution: The host computer control unit sends control commands through the CAN bus to control the servo electric cylinder pressure building unit to build up pressure to the target pressure according to the preset mode and maintain it stably. At the same time, it controls the ECU controller to drive the coil and motor of each tested HCU valve body to act according to the preset duty cycle and timing. The dynamic air cooling system dynamically adjusts the pressure and cooling time of the high-pressure cooling gas according to the current load and duration. The hydraulic circuit pressure, coil drive voltage and current data are collected at high frequency throughout the process. S65. Safety monitoring and fault handling: During the test, the pressure, current and equipment status are monitored in real time. If an abnormal pressure rise or current overload fault is detected, an emergency stop command is immediately triggered to stop the servo cylinder, cut off the power and release the pressure. S66. Data Processing and Report Generation: After the test is completed, the host computer control unit automatically parses the collected TDMS format data, calculates the pressure build-up rate and leakage rate characteristic values, plots performance curves and marks key points, generates a PDF test report with diagnostic suggestions, and archives the data according to a three-level classification storage structure of product model-production batch-individual product.

7. The method according to claim 6, characterized in that: The first level of the three-level classification storage structure is the product model level, where independent data storage directories are established according to different HCU models; the second level is the production batch level, where subdirectories are divided according to production batches under the same model directory; and the third level is the individual product level, where independent data folders are established under the same batch directory using the product serial number as a unique identifier.

8. The method according to claim 6, characterized in that: The high-pressure blowing time is 3-8s, the target vacuum degree of vacuum pumping is ≤-0.09MPa, and the number of times the servo electric cylinder reciprocates to build up pressure is 2-5 times.

9. The method according to claim 6, characterized in that: The pressure build-up rate of the servo electric cylinder is adjustable within the range of 0.1-5MPa / s, the stable holding time is 5-30s, and the data acquisition frequency is not less than 1kHz.

10. The method according to claim 6, characterized in that: The cooling pressure adjustment range of the dynamic air cooling system is 0.3-1.0 MPa, and the ratio of cooling time to test duration is 1:2-1:

5.

11. The method according to claim 6, characterized in that: The diagnostic suggestions are generated based on a preset fault knowledge base, including abnormal data feature matching and troubleshooting direction prompts for issues such as sealing ring leakage, valve core jamming, and abnormal coil resistance.

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