Commercial vehicle suspension system coupling test bench, control system and test method thereof

Abstract

The invention discloses a commercial vehicle suspension system coupling test bench, a control system and a test method thereof, the test bench comprises a four-column portal frame, a vertical loading unit, a decoupling force arm, a frame fixing support seat and a rotary loading counter-force unit, and the rotary loading counter-force unit can switch a transverse / longitudinal loading state to adapt to commercial vehicle suspension test. The control system comprises an upper computer touch screen unit and a lower computer unit, the upper computer touch screen unit comprises a parameter setting module, a process setting module and other module points, the lower computer unit comprises an MCU / ECU, an action control module and a fuzzy algorithm control module, instruction and data interaction is achieved through Ethernet communication, and control precision and data reliability are improved. The test method comprises the steps of configuration, transverse bending fatigue test, braking fatigue test and data monitoring termination, and short-period and high-precision fatigue reliability verification of the suspension is realized by standardizing a load applying rule. The problems that an existing test bed is poor in adaptability, high in cost and long in real vehicle test period are solved, and a low-cost and high-adaptability test scheme is provided.

Description

Technical Field

[0001] This invention relates to the field of commercial vehicle testing technology, and in particular to a commercial vehicle suspension system coupling test bench, control system and testing method. Background Technology

[0002] Currently, many multi-degree-of-freedom coupling test benches for automotive suspensions are primarily designed for passenger cars. However, due to the larger size and load of commercial vehicle chassis suspension systems, existing multi-degree-of-freedom coupling test benches suitable for general passenger cars cannot meet the testing requirements of commercial vehicle chassis suspension systems. Commercial vehicle suspensions are generally large in size and bear high loads, and the widespread use of leaf spring plus airbag composite suspensions makes their mechanical characteristics more complex, requiring dedicated commercial vehicle test benches. Purchasing new multi-degree-of-freedom coupling test benches is prohibitively expensive, typically requiring investments of hundreds of millions of yuan, which few companies can afford. Therefore, many commercial vehicle manufacturers have had to conduct chassis suspension system testing at proving grounds, performing real-vehicle tests to verify fatigue reliability under conditions such as heavy-load cornering and emergency braking. However, real-vehicle testing not only poses risks to the personal safety of test personnel but also cannot achieve high-frequency repeated loading, with test cycles lasting several months and costs remaining high. Furthermore, real-vehicle testing makes it difficult to accurately control load parameters and quantify subtle attitude changes of the suspension under extreme conditions, resulting in low-precision test data that is insufficient to support the optimized design of the suspension system. With the development of the logistics industry, users' requirements for the comfort and handling of commercial vehicles continue to increase, and the existing testing mode has become a bottleneck for the upgrading of commercial vehicle suspension technology. Summary of the Invention

[0003] The purpose of this invention is to provide a commercial vehicle suspension system coupling test bench to solve the problems of poor adaptability of existing passenger car test benches and high cost of dedicated commercial vehicle test benches, and to provide a low-cost, highly adaptable ground test equipment for commercial vehicle suspensions.

[0004] To address the aforementioned issues, the technical solution adopted in this test bench is as follows: This commercial vehicle suspension system coupling test bench includes a four-post gantry frame, a vertical loading unit, a decoupling arm, a frame fixing support, and a rotational loading reaction unit. Two vertical loading units are suspended on the four-post gantry frame. Each vertical loading unit is a heavy-duty servo hydraulic cylinder, and its output end is sequentially connected to a first force sensor and a decoupling arm. The decoupling arm is connected to the wheel hub of the suspension under test via a transition plate. Each decoupling arm corresponds to a set of rotational loading reaction units. The frame fixing support is located below the four-post gantry frame and is used to fix the frame of the suspension under test. The rotary loading reaction unit includes a servo hydraulic cylinder, a mounting plate, a reaction seat, and a second force sensor. The servo hydraulic cylinder is fixed to the reaction seat, which has multiple height adjustment holes, via the mounting plate. The output end of the servo hydraulic cylinder is connected to the decoupling arm via the second force sensor. Each group of rotary loading reaction units switches to two working states by adjusting the position of the reaction seat: one is a lateral loading state, in which the reaction seat is positioned on the lateral side of the decoupling arm, and the servo hydraulic cylinder is connected to the lateral surface of the decoupling arm via the second force sensor; the other is a longitudinal loading state, in which the reaction seat is positioned on the longitudinal side of the decoupling arm, and the servo hydraulic cylinder is connected to the longitudinal surface of the decoupling arm via the second force sensor. Both the lateral and longitudinal surfaces of the decoupling arm are provided with connection structures adapted to the second force sensor.

[0005] A more specific technical solution for the above-mentioned commercial vehicle suspension system coupling test bench can be as follows: the decoupling arm includes, from top to bottom, a loading section, a wheel end connection section, and a force-bearing section in the vertical direction. The top of the loading section has a first T-slot, which is engaged and fixed by a first connecting block hinged to the lower end of the first force sensor. The force-bearing section has a second T-slot with a four-sided double-groove structure, which is adapted to the connection structure of the second force sensor. The side of the loading section has a bending moment scale, the zero point of which is aligned with the transition plate and the wheel hub mounting surface. The side of the force-bearing section has a tire radius scale along the vertical direction, and a digital angle display instrument is mounted on the decoupling arm.

[0006] In some possible implementations, the transition plate includes a lever arm connection and a hub connection. The lever arm connection is provided with positioning screw holes in the circumferential direction, and the hub connection is provided with multiple sets of rim bolt holes of different specifications.

[0007] Another objective of this invention is to provide a coupling test control system for commercial vehicle suspension systems to address the problems of low load control accuracy, insufficient safety and data reliability in actual vehicle testing, thereby improving the controllability and data quality of commercial vehicle suspension tests.

[0008] To solve the above problems, the technical solution adopted by this control system is: a commercial vehicle suspension system coupling test control system, applied to the above-mentioned commercial vehicle suspension system test bench, including an upper computer touch screen unit, a lower computer unit and an Ethernet communication link; The host computer touch screen unit is equipped with a test parameter setting module, a test process setting module, a data dynamic display module, a force-position curve drawing module, a data storage and query module, and a first communication module; The lower-level machine unit includes an MCU / ECU and is equipped with an action control module, a fuzzy algorithm control module, and a second communication module. The Ethernet communication link connects the first communication module and the second communication module to enable instruction and data interaction between the upper and lower level machines; The host computer receives user input through the test parameter setting module and the test process setting module, and sends the parameters and instructions to the slave computer's second communication module via the first communication module and the Ethernet link. The slave computer's fuzzy algorithm control module receives the instruction parameters and feedback data from the force sensor, displacement sensor in the cylinder, and digital angle display of the test bench. After processing, it generates a control signal and sends it to the action control module to drive the loading unit of the test bench. The slave computer transmits real-time data back to the host computer via the second communication module. The host computer visualizes the data through the data dynamic display module and the force-position curve drawing module, and stores and retrieves the data through the data storage and query module.

[0009] In the above-mentioned technical solution of the coupling test control system for commercial vehicle suspension system, a more specific technical solution may be: the fuzzy algorithm control module is configured to: based on preset fuzzy rules and upper computer instructions, perform fuzzification, inference and defuzzification processing on the force value, displacement and tilt angle data fed back by the test bench, generate a precise control signal and send it to the action control module to realize closed-loop control of load application.

[0010] In some possible implementations, the test parameter setting module is configured to receive user input parameters including at least the target force value, target displacement value, test speed, or holding time.

[0011] In some possible implementations, a protection control module is also provided, which includes a force protection submodule, a displacement protection submodule, and an emergency stop interface; the force protection submodule is used to trigger a shutdown when the real-time force value exceeds a set range; the displacement protection submodule is used to stop the machine when the cylinder displacement exceeds a preset value; the emergency stop interface automatically records the force value, displacement, and timestamp data at the time of the fault during an emergency stop.

[0012] Another objective of this invention is to provide a coupling test method for commercial vehicle suspension systems, which solves the problems of long test cycles and inaccurate simulation of operating conditions in real vehicle testing. By standardizing load application rules and procedures, it enables short-cycle, high-precision fatigue reliability verification of commercial vehicle suspensions.

[0013] To address the aforementioned issues, the technical solution employed in this method is: a coupling test method for commercial vehicle suspension systems, applied to the aforementioned commercial vehicle suspension system test bench, comprising the following steps: Test configuration steps: Based on the full-load axle load G of the commercial vehicle under test, set the target load of the vertical loading unit, and configure the working state of the rotary loading reaction unit according to the test type; First test execution steps: When conducting the transverse bending fatigue test, control the vertical loading unit to apply vertical alternating loads Fz1 and Fz2 with a phase difference of 180 degrees, and control the rotary loading reaction unit in the transverse loading state to apply transverse alternating loads Fy1 and Fy2, with Fz1 and Fy1 in phase, and Fz2 and Fy2 in phase; where Fz1 is the vertical load at the left wheel end of the vehicle, Fz2 is the vertical load at the right wheel end of the vehicle, and Fy1 is the transverse load at the left wheel end of the vehicle. The load Fy2 is the lateral load on the right wheel end of the vehicle; the second test execution step: when conducting the brake fatigue test, the vertical loading unit is controlled to apply a constant vertical load Fz, and the rotating loading reaction unit in the longitudinal loading state is controlled to apply multiple forward braking loads Fx1 and one rearward braking load Fx2 in one test cycle; where Fx1 is the wheel end braking load in the forward direction of the vehicle, and Fx2 is the wheel end braking load in the reverse direction of the vehicle; data monitoring and termination steps: in the first or second test execution step, the load and suspension attitude are monitored in real time by force sensor and digital display angle meter until the test reaches the predetermined number of cycles or the suspension system fails.

[0014] In the above-mentioned technical solution of the coupling test method for commercial vehicle suspension system, a more specific technical solution may be: in the first test execution step, Fz1=Fz2=-0.2G~-1.25G, Fy1=Fy2=0~0.4G, where '-' represents tension and G is the full-load axle load of the vehicle; the test load waveform is a sine wave with a frequency of 0.2Hz.

[0015] In some possible implementations, in the second test execution step, Fz=G, Fx1=Fx2=0.3G, where G is the full-load axle load of the vehicle; the test load waveform is a sine wave with a frequency of 0.5Hz to 2Hz.

[0016] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. The test bench enables precise laboratory testing of large-size, high-load, and complex mechanical characteristics suspensions for commercial vehicles in a low-cost and highly adaptable manner. Its four-post gantry frame combined with a rotary loading reaction unit that can switch working states allows for loading under both lateral and longitudinal conditions, avoiding the need to purchase multiple sets of dedicated equipment for different test items and greatly reducing equipment investment costs. It adopts heavy-duty servo hydraulic cylinders and frame-fixed support seats, specifically designed for the characteristics of large size and high load of commercial vehicles. The decoupling arm and transition plate serve as intermediate connecting parts, realizing multi-directional connection between the loading unit and the suspension under test, avoiding mutual interference of multi-directional loads, achieving independent and precise control of the stress state of the suspension in each direction, and improving adaptability to different commercial vehicle models with different wheelbases and leaf spring-airbag composite suspensions.

[0017] 2. A scale is set on the decoupling lever arm. The bending moment scale ensures accurate calculation of the applied torque and eliminates test data deviations caused by installation errors. The tire radius scale can quickly set the loading lever arm to simulate the force conditions at the real tire contact point, achieving high-precision reproduction of real vehicle working conditions in a laboratory environment. A digital display angle meter is set up to quantify the attitude changes of the suspension under load in real time and accurately. The T-slot connection method is flexible, providing multi-angle and multi-position connection, enhancing the adaptability to different sensors and reaction force units.

[0018] 3. The transition plate is equipped with multiple sets of wheel rim bolt holes of different specifications, which allows the test bench to quickly connect wheel hubs of different brands and models of commercial vehicles without the need to customize special tooling for each vehicle model, significantly shortening the test preparation time and improving the utilization rate of the equipment.

[0019] 4. A control system integrating control, monitoring, and data processing was constructed. Through real-time feedback from force sensors, displacement sensors, and digital angle meters, combined with rapid processing by the lower-level computer, a closed-loop control was formed, ensuring the consistency of loading in each test. The upper-level computer touch screen unit provides an intuitive interface for parameter setting, process control, and data visualization. The data storage and query module can systematically record and manage massive amounts of test data, greatly improving data reliability. The upper and lower-level computers are separated via Ethernet, making the system structure clear, easy to maintain and upgrade, and providing the possibility for remote monitoring and operation.

[0020] 5. The fuzzy algorithm control module can handle problems such as system nonlinearity and time-varying parameters. It does not rely on a precise mathematical model, but rather on reasoning based on fuzzy rules, i.e., expert experience, so that the control system can still maintain the accuracy and stability of load application when facing various situations.

[0021] 6. The test parameter setting module allows all load parameters to be preset, avoiding the arbitrariness of manual operation.

[0022] 7. The force and displacement protection of the protection control module can prevent overload from causing mechanical damage to the suspension sample or test bench itself; the emergency stop interface and fault data recording function can not only respond quickly in emergency situations, but also provide a complete data chain for subsequent accident analysis, fundamentally improving the safety of laboratory testing compared to dangerous real vehicle testing.

[0023] 8. The test methods provide a standardized and repeatable laboratory testing process, replacing expensive and inefficient real-vehicle testing; the load application methods for two typical harsh conditions, lateral bending fatigue and braking fatigue, enable accurate laboratory simulation of real-vehicle heavy-load cornering, emergency braking, and other conditions, and can be repeated at high frequency; fatigue testing that would take months for a real vehicle can be completed in a few days or weeks on the test bench, significantly reducing time and manpower costs and accelerating product development and optimization iteration; real-time monitoring of load and suspension attitude until failure can accurately obtain the fatigue life and failure mode of the suspension system, providing direct basis for reliability design and material selection.

[0024] 9. By quantifying specific load parameters, the scientific nature and comparability of the test were ensured; the proportional relationship between the load and the full-load axle load G was clarified, so that the test conditions were based on the actual use of the vehicle, ensuring the engineering reference value of the test results; the given frequency range not only considered the frequency response characteristics of simulating real working conditions, but also took into account the needs of accelerated fatigue testing in the laboratory, and further compressed the test cycle while ensuring the validity of the data. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the commercial vehicle suspension system testing device.

[0026] Figure 2 This is a schematic diagram of another state of the commercial vehicle suspension system test device.

[0027] Figure 3 This is an exploded view of the wheel end assembly.

[0028] Figure 4 This is a schematic diagram of the decoupling lever arm and assembly structure.

[0029] Figure 5 This is a schematic diagram of the assembly structure for a transverse bending fatigue test.

[0030] Figure 6 This is a schematic diagram of the assembly structure for the brake fatigue test.

[0031] Figure 7 This is a schematic diagram of the structure of the test control system for the suspension system of this commercial vehicle.

[0032] Figure 8 This is a force-displacement dual-parameter protection control logic diagram.

[0033] Figure 9 This is a logic diagram for controlling the number of tests and providing emergency stop protection.

[0034] The following are the labels in the diagram: 1. Four-column gantry; 2. Heavy-duty servo hydraulic cylinder; 3. First force sensor; 4. Decoupling lever arm; 4-1. Loading section; 4-11. First T-slot; 4-2. Wheel end connection section; 4-3. Force-bearing section; 4-31. Second T-slot; 4-4. Bending moment scale; 4-5. Digital angle gauge; 4-6. Tire radius scale; 5. Transition plate; 5-1. Lever arm connection part; 5-2. Wheel hub connection part; 6. Wheel hub; 7. Frame; 8. Frame fixing support; 9. Second force sensor; 10. Servo hydraulic cylinder; 11. Mounting plate; 12. Reaction seat. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Figure 1 and Figure 2 The commercial vehicle suspension system testing apparatus shown mainly includes a gantry load-bearing frame, a vertical loading unit, a decoupling arm 4, a frame fixing support 8, and a rotational loading reaction unit. The gantry load-bearing frame preferably uses a four-column gantry 1, which consists of two gantry frames and a top crossbeam connecting them, forming a stable frame that provides sufficient rigidity and strength for the entire apparatus when subjected to extreme loads during commercial vehicle suspension system testing. The vertical loading unit uses heavy-duty servo hydraulic cylinders 2, two of which are suspended on the lower flange of the top crossbeam of the four-column gantry 1, simulating the core power source of the vehicle's axle load. Each heavy-duty servo hydraulic cylinder 2 has a first force sensor 3 and a decoupling arm 4 connected sequentially to its output end. The first force sensor 3 is responsible for real-time and accurate measurement of the vertical load, ensuring the accuracy of the test data. The decoupling arm 4 is firmly connected to the wheel hub 6 of the suspension under test via a transition plate 5, thus realistically transferring the simulated laboratory load to the suspension system. Meanwhile, the frame 7 of the commercial vehicle suspension system under test is rigidly fixed to the frame fixing support 8 installed below the gantry load-bearing frame.

[0036] like Figure 3As shown, to simulate complex actual working conditions, each decoupling arm 4 of this invention is equipped with a set of rotary loading reaction units. These units consist of a servo hydraulic cylinder 10, a mounting plate 11, a reaction seat 12, and a second force sensor 9. The output end of the servo hydraulic cylinder 10 is connected to the second force sensor 9 via a flange to ensure accurate acquisition of longitudinal or lateral loads. The other end is fixed to the reaction seat 12 via the mounting plate 11. By adjusting the positioning of the reaction seat 12, the entire unit can switch between two working states: lateral loading and longitudinal loading. When simulating a curve, the reaction seat 12 is positioned on the lateral side of the decoupling arm 4, so that the servo hydraulic cylinder 10 is connected to the lateral surface of the decoupling arm 4 via the second force sensor 9, thus achieving the lateral loading state. When simulating braking or driving conditions, the reaction seat 12 is simply moved to the longitudinal side of the decoupling arm 4, and the servo hydraulic cylinder 10 is connected to the longitudinal surface of the decoupling arm 4 via the second force sensor 9, thus switching to the longitudinal loading state.

[0037] It is worth mentioning that the frame mounting support 8 has multiple height adjustment holes for fixing the mounting plate 11 of the rotational loading reaction unit. This allows the overall installation height of the reaction unit to be flexibly adjusted according to the ground clearance and suspension travel of different commercial vehicles, further enhancing the adaptability of the entire device to different vehicle models.

[0038] like Figure 4As shown, the decoupling arm 4 is vertically divided into a loading section 4-1, a wheel end connecting section 4-2, and a force-bearing section 4-3. The loading section 4-1 is hinged to the first force sensor 3, the wheel end connecting section 4-2 is connected to the wheel hub 6 via a transition plate 5, and the force-bearing section 4-3 is hinged to the second force sensor 9. The top of the loading section 4-1 has a first T-slot 4-11, which quickly engages with the connecting block hinged to the lower end of the first force sensor 3 and is then locked with bolts. This not only achieves a gapless and highly rigid connection, ensuring the lossless transmission of vertical load from the cylinder to the decoupling arm 4, but also enables rapid installation and disassembly, effectively improving the equipment adjustment efficiency. More importantly, the decoupling arm 4 has connection structures adapted to the second force sensor 9 on both its transverse and longitudinal surfaces. Specifically, a second T-slot 4-31 with a four-sided double-groove structure is opened in the force-bearing section of the decoupling arm 4. The free end of the second force sensor 9 has a connection structure adapted to the second T-slot 4-31 of the decoupling arm 4. Quick connection is achieved by the T-block engaging with the slot. This provides a standardized mechanical interface for connecting the rotary loading reaction unit from four directions, giving the device extremely high loading flexibility. To further improve the accuracy and convenience of testing, a digital display angle meter 4-5 is also integrated on the decoupling arm 4 for real-time monitoring of the attitude angle changes of the suspension system. The decoupling arm 4 has a bending moment scale 4-4 on its side of the loading section 4-1. The zero point of the bending moment scale 4-4 is precisely aligned with the wheel hub mounting surface, which can guide the operator to quickly and accurately adjust the vertical loading point to the center of the wheel, eliminating the additional bending moment caused by inaccurate loading point and ensuring the accuracy and repeatability of the test. At the same time, the tire radius scale 4-6 set vertically along the force section 4-3 can help to quickly set the lateral or longitudinal loading height according to the tire specifications of the suspension under test, so as to accurately simulate the contact point of different tire specifications and make the test conditions closer to the real vehicle conditions.

[0039] To accommodate various types of commercial vehicle suspensions and different wheel hub sizes 6, the transition plate 5 in this embodiment consists of a lever arm connecting part 5-1 and a wheel hub connecting part 5-2. The lever arm connecting part 5-1 has multiple circumferentially arranged positioning screw holes, combined with multiple sets of wheel rim bolt holes of different sizes on the wheel hub connecting part 5-2. The transition plate can adopt a split structure, allowing the device to quickly adapt to diverse commercial vehicle wheel hubs by replacing or adjusting the wheel hub connecting part 5-2, significantly improving the equipment's versatility and testing efficiency. During assembly, the wheel hub connecting part 5-2 is first fastened to the left and right wheel hubs of the suspension under test using wheel rim bolts. Then, the lever arm connecting part 5-1 is fixed to the wheel end connecting section 4-2 of the decoupling lever arm 4 to complete the rigid connection between the wheel hub 6 and the decoupling lever arm 4, ensuring effective load transfer from the decoupling lever arm 4 to the suspension system.

[0040] This commercial vehicle suspension system testing device can perform tests under various working conditions according to testing requirements. Among them, the lateral bending fatigue test and the braking fatigue test are the most typical application scenarios. The two share the same set of equipment, and the working conditions can be switched by simply adjusting the assembly direction of the rotation loading reaction unit. Each functional unit will be assembled in sequence according to the logic of "vertical loading - force transmission - suspension under test fixing - lateral loading" to form a complete load application and transmission path.

[0041] Lateral bending fatigue testing primarily simulates the stress state of a commercial vehicle's suspension system under cornering conditions. The core of the test lies in precisely positioning the rotating reaction force unit to the lateral side to apply periodic lateral loads to simulate centrifugal force during cornering. For example... Figure 5 As shown, during the lateral bending fatigue test, the rotary loading reaction unit is placed in a lateral loading state, the vertical loading unit applies an axle load Fz, and the lateral loading unit applies a lateral force Fy to simulate the vehicle's cornering condition. Before the test begins, the two sets of rotary loading reaction units are fixed to the corresponding positions on the frame mounting support using mounting plates, ensuring the reaction seats are precisely positioned on the lateral side of the decoupling arm. The unit height is then adjusted to align the axis of the servo hydraulic cylinder with the lateral direction of the decoupling arm, forming a stable lateral load application path. Next, the commercial vehicle suspension system under test is fixed to the frame mounting support, and the support height is adjusted using the height adjustment hole to ensure the suspension is initially horizontal. Then, the decoupling arm is connected to the left and right wheel hubs using a transition plate. At this point, the vertical loading point is aligned with the wheel center using a moment scale, and the loading height matching the actual vehicle is set using a tire radius scale. The digital angle meter is then activated to zero the initial parameters, ensuring the initial test conditions are consistent with the actual vehicle conditions. During the test, the heavy-duty servo hydraulic cylinder of the vertical loading unit applies vertical loads according to a preset program to simulate the vehicle's own weight and load. At the same time, the servo hydraulic cylinder of the lateral side rotation loading reaction unit applies periodic lateral loads to simulate the centrifugal force of a curve. During this process, the first force sensor and the second force sensor collect vertical and lateral load data in real time, and the digital display angle instrument continuously records the changes in suspension tilt angle. All data are transmitted to the control system in a synchronized manner. By analyzing these data, the staff can accurately assess the lateral bending fatigue performance of the suspension. The entire process does not require dangerous real vehicle road tests, which not only ensures personnel safety but also significantly shortens the test cycle.

[0042] When braking fatigue testing is required, only the assembly direction of the rotating loading reaction unit needs to be adjusted. For example... Figure 6As shown, the rotary loading reaction unit is rotated 90° to the longitudinal loading state. This test is used to simulate the stress on the suspension system under heavy-load braking conditions of commercial vehicles. A stable vertical load Fz is continuously applied by the vertical loading unit to simulate the axle load state of the vehicle during braking. At the same time, the longitudinal loading unit applies a longitudinal load Fx to simulate the braking force and restoring force during the braking process. Before the test, ensure that the vertical load application conditions are consistent with the axle load state of the actual vehicle during braking. The digital angle display and force sensor also need to be recalibrated initially to avoid interference from the previous test data. When switching the rotary loading reaction unit, first remove the connecting bolts between the rotary loading reaction unit and the frame fixed support. Rotate the entire rotary loading reaction unit 90° around the decoupling arm to transfer the reaction seat from the lateral side to the longitudinal side of the decoupling arm. Then, readjust the fixed position of the mounting plate on the frame fixed support. Align the second force sensor with the longitudinal surface of the decoupling arm to complete the connection, so that the axis of the servo hydraulic cylinder coincides with the longitudinal direction of the decoupling arm, forming a stable longitudinal load application path. During the test, the vertical loading unit continuously applies a stable vertical load to simulate the vehicle load state during braking. Under this state, the servo hydraulic cylinder of the longitudinal side rotating loading reaction unit applies periodic longitudinal tension and pressure to accurately simulate the alternating action of braking force and restoring force during braking. During the test, the first force sensor monitors the stability of the vertical load in real time to ensure the consistency of test conditions, the second force sensor accurately collects the changes in longitudinal load, and the digital angle meter records the tilt angle fluctuations of the suspension during braking. These data together provide a reliable basis for verifying the braking fatigue performance of the suspension, thus comprehensively simulating emergency braking conditions and achieving a comprehensive assessment of the reliability of the suspension system under braking conditions.

[0043] When this device is no longer used for automotive suspension testing, the suspension can be removed, and heavy-duty servo hydraulic cylinders can be used to complete vertical bending fatigue tests on axle housings, front axles, etc., improving the efficiency of the test bench and greatly reducing the development cost of the test bench.

[0044] Figure 7 The diagram shows the core architecture of the coupling test control system for the commercial vehicle suspension system. The system adopts a master-slave mode and is connected via an Ethernet communication link, combining powerful computing and control capabilities with a user-friendly human-machine interface.

[0045] The host computer touchscreen unit serves as the user's interface with the test bench. Operators can intuitively input or select key parameters for the test through its test parameter setting module. These parameters include at least the target force value, target displacement value, test speed, and load holding time. For example, before the transverse bending fatigue test, the vertical loads Fz1 and Fz2 can be set to a range of -0.2G to -1.25G, and the transverse loads Fy1 and Fy2 to a range of 0 to 0.4G. Through the test procedure setting module, users can program complex test steps, such as pre-loading before entering the main cycle test. After the test begins, the data dynamic display module refreshes the force, displacement, and angle data from each sensor in real time, using digital data and a dashboard format. The force-displacement curve plotting module simultaneously plots key curves such as load-time and displacement-time, making the test process readily apparent. All data is automatically recorded by the data storage and query module with timestamps for easy subsequent traceability, analysis, and report generation. The host computer sends control commands and parameters to the slave computer via Ethernet through its first communication module, and receives real-time data returned by the slave computer.

[0046] The lower-level MCU / ECU (Microcontroller Unit / Electronic Control Unit) is responsible for receiving instructions from the upper-level computer and driving precise hardware actions. Its second communication module is responsible for receiving all instructions and parameters from the upper-level computer. The motion control module directly sends control signals to the servo hydraulic cylinders of the heavy-duty servo hydraulic cylinders and the rotary loading reaction unit. To ensure the accuracy and stability of load control, a fuzzy algorithm control module is introduced into the system. This module is configured to: based on preset fuzzy rules and upper-level computer instructions, perform fuzzification, inference, and defuzzification processing on the force, displacement, and tilt angle data fed back from the test bench, generating precise control signals to be sent to the motion control module. Specifically, the module receives instruction parameters from the upper-level computer and feedback data from the first force sensor, the second force sensor, the cylinder's built-in displacement sensor, and the digital angle meter in real time, converts these precise clear values ​​into fuzzy quantities, performs inference according to fuzzy rules, and finally defuzzifies the inference results to generate precise control signals. This mechanism effectively overcomes the inherent nonlinearity and time-varying parameter problems of hydraulic systems, achieving high-precision, adaptive closed-loop control of load application.

[0047] The timing of the entire control process is as follows: After the system powers on and initializes, the touchscreen and MCU / ECU first establish a communication connection. The user completes parameter settings on the host computer and issues a start command, and the touchscreen sends control parameters to the MCU / ECU. After receiving the start signal, the MCU / ECU starts the test cycle and drives the loading unit to vibrate. During this process, the lower-level computer acquires feedback data such as loading force, displacement, and angle in real time. This data is used for closed-loop adjustment of the fuzzy algorithm control module and is also transmitted back to the host computer via the communication link. After receiving this real-time data, the host computer dynamically displays the force-position curve and stores it. This cycle will continue until the test task is completed.

[0048] The protection control module in this control system ensures that the safety protection mechanism is implemented in every aspect of the control process.

[0049] like Figure 8 The diagram shows the real-time protection control logic for both force and displacement parameters. This module includes a force protection submodule and a displacement protection submodule. The force protection submodule continuously monitors the readings of each force sensor; if the real-time force value exceeds the set range, it immediately triggers a shutdown to prevent overload damage to the test specimen or equipment. The displacement protection submodule monitors the cylinder stroke to prevent shutdown due to displacement exceeding a preset value. This effectively avoids equipment damage or instability caused by misoperation or sudden specimen breakage.

[0050] like Figure 9 The diagram illustrates the test cycle control and emergency stop protection logic. The control system rigorously counts the number of test cycles and automatically terminates the test normally after reaching the preset number. Simultaneously, the system hardware includes an emergency stop interface. Regardless of whether in automatic or manual mode, pressing the emergency stop switch in case of an emergency will trigger the highest-priority emergency stop. Crucially, upon triggering an emergency stop or the aforementioned protective stop, the system automatically records and saves the force value, displacement, and precise timestamp data at the moment of the fault, providing a complete and reliable data chain for subsequent fault analysis. Throughout the control process, the system continuously determines whether the test piece is damaged or an emergency stop has been triggered. If so, it immediately jumps to the end process; if not, it continues to determine whether the task has been completed, thus ensuring the safe and controlled operation of the test.

[0051] Based on the above-mentioned test apparatus and control system, the commercial vehicle suspension system coupling test method of the present invention accurately replicates the actual vehicle operating conditions in the laboratory through a standardized process. The specific implementation steps are as follows: First, the test configuration steps are performed. The operator sets the target load of the vertical loading unit in the host computer based on the full-load axle load G of the commercial vehicle under test. Simultaneously, depending on the type of test—transverse bending fatigue test or braking fatigue test—the lateral or longitudinal loading operation of the rotary loading reaction unit is adjusted on-site, as described above. Figure 5, Figure 6 As shown, precise positioning is achieved through the bending moment scale and tire radius scale on the decoupling arm to ensure that the loading conditions are consistent with the actual vehicle conditions.

[0052] Subsequently, the test execution phase begins. This system primarily supports two typical fatigue tests: 1. First Test Procedure: Lateral Bending Fatigue Test. This test simulates the heavy-load cornering conditions of a vehicle. The control system controls two vertical loading units to apply vertical alternating loads Fz1 and Fz2 with a phase difference of 180 degrees to the left and right wheel ends. Specifically, Fz1 = Fz2 = -0.2G ~ -1.25G, where '-' indicates tension. Simultaneously, two rotating loading reaction units in a lateral loading state are controlled to apply lateral alternating loads Fy1 and Fy2, with Fz1 and Fy1 in phase, and Fz2 and Fy2 in phase. Fy1 = Fy2 = 0 ~ 0.4G. The test load waveform uses a sine wave with a frequency set to 0.2Hz. This coupling of in-phase vertical and lateral loads accurately simulates the harsh stress state of the vehicle in a corner, where the outer suspension simultaneously bears the vehicle's sinking and centrifugal force.

[0053] 2. Second Test Execution Step: Braking Fatigue Test. This test simulates emergency braking and reverse braking conditions of the vehicle. In this step, a constant vertical load Fz, where Fz = G, is applied by the vertical loading unit to simulate the static axle load during braking. Simultaneously, the rotating loading reaction unit, under longitudinal loading, applies four forward braking loads Fx1 to simulate forward braking and one rearward braking load Fx2 to simulate reverse braking within a complete test cycle. Fx1 = Fx2 = 0.3G. The test load waveform is also a sine wave, but with a higher frequency, ranging from 0.5Hz to 2Hz, to achieve accelerated fatigue testing and significantly shorten the test cycle.

[0054] Finally, data monitoring and termination procedures are performed throughout the entire test. The system monitors all load data and suspension attitude in real time, such as subtle changes in roll angle and toe angle, using force sensors and digital angle gauges on the decoupled lever arm. The test will continue until the preset number of cycles is reached, or until suspension system failure occurs, such as leaf spring breakage, airbag deflation, or loosening of connectors. The host computer will record all data from start to finish, providing solid data support for evaluating the fatigue reliability of the suspension system and optimizing its design.

[0055] This testing method allows real-vehicle road tests, which previously required months at the test track, to be completed in just a few days or weeks in the laboratory. This greatly shortens the product development cycle, reduces testing costs and safety risks, and yields far more accurate and repeatable quantitative data than real-vehicle testing.

Claims

1. A coupling test bench for a commercial vehicle suspension system, characterized in that: The system includes a four-post gantry, vertical loading units, decoupling arms, a frame fixing support, and a rotational loading reaction unit. Two vertical loading units are suspended on the four-post gantry. Each vertical loading unit is a heavy-duty servo hydraulic cylinder, and its output end is sequentially connected to a first force sensor and a decoupling arm. The decoupling arm is connected to the wheel hub of the suspension under test through a transition plate. Each decoupling arm corresponds to a set of rotational loading reaction units. The frame fixing support is located below the four-post gantry and is used to fix the frame of the suspension under test. The rotary loading reaction unit includes a servo hydraulic cylinder, a mounting plate, a reaction seat, and a second force sensor. The servo hydraulic cylinder is fixed to the reaction seat, which has multiple height adjustment holes, via the mounting plate. The output end of the servo hydraulic cylinder is connected to the decoupling arm via the second force sensor. Each group of rotary loading reaction units switches to two working states by adjusting the position of the reaction seat: one is a lateral loading state, in which the reaction seat is positioned on the lateral side of the decoupling arm, and the servo hydraulic cylinder is connected to the lateral surface of the decoupling arm via the second force sensor; the other is a longitudinal loading state, in which the reaction seat is positioned on the longitudinal side of the decoupling arm, and the servo hydraulic cylinder is connected to the longitudinal surface of the decoupling arm via the second force sensor. Both the lateral and longitudinal surfaces of the decoupling arm are provided with connection structures adapted to the second force sensor.

2. The commercial vehicle suspension system coupling test bench according to claim 1, characterized in that: The decoupling arm, from top to bottom vertically, includes a loading section, a wheel end connecting section, and a force-bearing section. The top of the loading section has a first T-slot, which is engaged and fixed by a first connecting block hinged to the lower end of the first force sensor. The force-bearing section has a second T-slot with a four-sided double-groove structure, which is adapted to the connection structure of the second force sensor. The side of the loading section has a bending moment scale, the zero point of which is aligned with the transition plate and the wheel hub mounting surface. The side of the force-bearing section has a tire radius scale along the vertical direction. A digital angle display instrument is mounted on the decoupling arm.

3. The control system for coupling test of commercial vehicle suspension system according to claim 2, characterized in that: The transition plate includes a lever arm connecting part and a hub connecting part. The lever arm connecting part is provided with positioning screw holes in the circumference, and the hub connecting part is provided with multiple sets of rim bolt holes of different specifications.

4. A coupling test control system for a commercial vehicle suspension system, characterized in that: The test bench for commercial vehicle suspension systems as described in any one of claims 1 to 3 includes an upper computer touch screen unit, a lower computer unit, and an Ethernet communication link; The host computer touch screen unit is equipped with a test parameter setting module, a test process setting module, a data dynamic display module, a force-position curve drawing module, a data storage and query module, and a first communication module; The lower-level machine unit includes an MCU / ECU and is equipped with an action control module, a fuzzy algorithm control module, and a second communication module. The Ethernet communication link connects the first communication module and the second communication module to enable instruction and data interaction between the upper and lower level machines; The host computer receives user input through the test parameter setting module and the test process setting module, and sends the parameters and instructions to the slave computer's second communication module via the first communication module and the Ethernet link. The slave computer's fuzzy algorithm control module receives the instruction parameters and feedback data from the force sensor, displacement sensor in the cylinder, and digital angle display of the test bench. After processing, it generates a control signal and sends it to the action control module to drive the loading unit of the test bench. The slave computer transmits real-time data back to the host computer via the second communication module. The host computer visualizes the data through the data dynamic display module and the force-position curve drawing module, and stores and retrieves the data through the data storage and query module.

5. The commercial vehicle suspension system coupling test control system according to claim 4, characterized in that: The fuzzy algorithm control module is configured to: based on preset fuzzy rules and host computer instructions, perform fuzzification, inference, and defuzzification processing on the force, displacement, and tilt angle data fed back from the test bench, generate precise control signals and send them to the motion control module to realize closed-loop control of load application.

6. The commercial vehicle suspension system coupling test control system according to claim 4, characterized in that: The test parameter setting module is configured to receive user input parameters including at least the target force value, target displacement value, test speed, or holding time.

7. The commercial vehicle suspension system coupling test control system according to claim 4, characterized in that: It is also equipped with a protection control module, which includes a force protection submodule, a displacement protection submodule, and an emergency stop interface; the force protection submodule is used to trigger a shutdown when the real-time force value exceeds the set range; the displacement protection submodule is used to stop the machine when the cylinder displacement exceeds the preset value; the emergency stop interface automatically records the force value, displacement, and timestamp data at the time of the fault during an emergency stop.

8. A coupling test method for a commercial vehicle suspension system, characterized in that: Applied to the commercial vehicle suspension system test bench according to any one of claims 1 to 3, the method includes the following steps: Test configuration steps: Based on the full-load axle load G of the commercial vehicle under test, set the target load of the vertical loading unit, and configure the working state of the rotary loading reaction unit according to the test type; First test execution steps: When conducting the transverse bending fatigue test, control the vertical loading unit to apply vertical alternating loads Fz1 and Fz2 with a phase difference of 180 degrees, and control the rotary loading reaction unit in the transverse loading state to apply transverse alternating loads Fy1 and Fy2, with Fz1 and Fy1 in phase, and Fz2 and Fy2 in phase; where Fz1 is the vertical load at the left wheel end of the vehicle, Fz2 is the vertical load at the right wheel end of the vehicle, and Fy1 is the transverse load at the left wheel end of the vehicle. The load Fy2 is the lateral load on the right wheel end of the vehicle; the second test execution step: when conducting the brake fatigue test, the vertical loading unit is controlled to apply a constant vertical load Fz, and the rotating loading reaction unit in the longitudinal loading state is controlled to apply multiple forward braking loads Fx1 and one rearward braking load Fx2 in one test cycle; where Fx1 is the wheel end braking load in the forward direction of the vehicle, and Fx2 is the wheel end braking load in the reverse direction of the vehicle; data monitoring and termination steps: in the first or second test execution step, the load and suspension attitude are monitored in real time by force sensor and digital display angle meter until the test reaches the predetermined number of cycles or the suspension system fails.

9. The commercial vehicle suspension system coupling test method according to claim 8, characterized in that: In the first test execution step, Fz1=Fz2=-0.2G~-1.25G, Fy1=Fy2=0~0.4G, where '-' represents tension and G is the full-load axle load of the vehicle; the test load waveform is a sine wave with a frequency of 0.2Hz.

10. The commercial vehicle suspension system coupling test method according to claim 8, characterized in that: In the second test execution step, Fz=G, Fx1=Fx2=0.3G, where G is the full-load axle load of the vehicle; the test load waveform is a sine wave with a frequency of 0.5Hz to 2Hz.

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