A dynamic force test method for a suspension shock absorber under whole vehicle working conditions

Abstract

The present application is suitable for the technical field of automobile suspension testing, and provides a kind of suspension damper whole vehicle operating condition dynamic force testing method, this method is arranged strain sensor on the surface of suspension spring, and is arranged displacement sensor along the movement direction of damper;Three groups of corresponding relations of damper stroke and spring total stress, buffer block deformation and acting force, damper damping force and movement speed are obtained in advance;Strain and displacement signals are synchronously collected under real vehicle driving condition, buffer block acting force is solved according to displacement signal and the contact state of buffer block and cap is judged, damper speed is obtained by filtering and deriving displacement signal to solve damper damping force, spring pure stress is solved in combination with contact state, and total dynamic force of damper is obtained by superimposing corresponding component force in different states;The present application does not need to disassemble suspension and special force sensor, is convenient to operate, low in cost, can accurately obtain total dynamic force of damper under whole vehicle operating condition and each component force composition, provides reliable data support for chassis tuning and suspension optimization.

Description

Technical Field

[0001] This invention relates to the field of automotive suspension testing technology, specifically a method for testing the dynamic force of suspension dampers under vehicle operating conditions. Background Technology

[0002] The total dynamic force exerted on the vehicle body by the suspension dampers directly affects the vehicle's ride comfort, handling stability, and NVH performance, and is a key prerequisite parameter for chassis design, tuning, and suspension optimization.

[0003] Currently, there are two main types of testing methods in the industry: Firstly, the bench test method requires disassembling the shock absorber for testing, which cannot simulate complex working conditions such as bumps, speed bumps, and steering of a real vehicle. The test results deviate greatly from the actual force, and the reference value is limited. The second method is the real vehicle testing method, which requires the installation of multiple dedicated force sensors. This method is complex, costly, and can easily damage the original suspension structure. It is also difficult to take into account the coordinated force of the spring, buffer block, and shock absorber. Some methods ignore the force of the buffer block or shock absorber. In addition, it is easily affected by factors such as vehicle vibration and temperature, and cannot accurately obtain the total dynamic force of the shock absorber.

[0004] Furthermore, existing real-vehicle testing methods are susceptible to interference from vehicle vibrations and temperature changes, and some technical solutions neglect the force exerted by the buffer block under extreme operating conditions, resulting in insufficient accuracy of the final measurement results. Therefore, in view of the above situation, there is an urgent need to provide a dynamic force testing method for suspension shock absorbers under vehicle operating conditions to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a method for testing the dynamic force of suspension dampers under vehicle operating conditions, effectively solving the problems mentioned in the background art.

[0006] This invention is implemented as follows: a method for testing the dynamic force of a suspension shock absorber under vehicle operating conditions, comprising the following steps: S1. Install strain sensors on the surface of the suspension springs and displacement sensors along the direction of motion of the shock absorber. S2. Pre-obtain the correspondence between the spring strain of the shock absorber and the total force of the spring, Ft1; pre-obtain the correspondence between the deformation of the buffer block and the applied force; pre-obtain the correspondence between the damping force of the shock absorber and the motion speed. S3. Under actual vehicle driving conditions, simultaneously collect the strain signal from the strain sensor and the displacement signal from the displacement sensor. S4. Calculate the force Fh2 of the buffer block based on the displacement signal and determine the contact state between the buffer block and the cap. The velocity of the damper is obtained by differentiating the displacement signal, and the damping force Fj3 of the damper is calculated by combining the relationship between the damper damping force and the velocity. Based on the contact state of the buffer block, the pure force Ft2 of the spring is calculated by combining the total force Ft1 of the spring and the force Fh2 of the buffer block. The total dynamic force F of the shock absorber is obtained by superimposing the corresponding component forces based on the contact state of the buffer block.

[0007] As a further aspect of the present invention: in S1, the strain sensor is a strain gauge sensor, which is attached to the uniformly stressed area of ​​the suspension spring. The detection direction of the displacement sensor is consistent with the extension and retraction direction of the shock absorber.

[0008] As a further aspect of the present invention: in S1, both the strain sensor and the displacement sensor are connected to the data acquisition instrument to achieve synchronous acquisition of strain signals and displacement signals.

[0009] As a further aspect of the present invention: in S2, the correspondence between the shock absorber stroke and the total force on the spring, Ft1, is obtained by calibration. The relationships between the deformation of the buffer block and the applied force, and between the damping force of the shock absorber and the motion speed, were obtained through bench testing.

[0010] As a further aspect of the present invention: in S2 and S3, the bench damping force test, bench spring force calibration, buffer block force test and vehicle operating conditions are combined to dynamically calculate the composition of various forces of the suspension damper and the magnitude of each component.

[0011] As a further aspect of the present invention: in S4, the contact state between the buffer block and the cap is determined based on the damper stroke corresponding to the displacement signal. When the buffer block is in a free state and not in contact with the cap, it is determined to be in a non-contact state; When the buffer block comes into contact with the cap, it is determined to be in a contact state.

[0012] As a further aspect of the present invention: In S4, the pure force value Ft2 of the spring is calculated based on the contact state, specifically as follows: When the buffer block is in an uncontacted state, Ft2 = Ft1; When the buffer block is in contact, Ft2 = Ft1 - Fh2.

[0013] As a further aspect of the present invention: in S4, the superposition method of the total dynamic force F is as follows: When the buffer block is in an uncontacted state, F = Ft2 + Fj3; When the buffer block is in contact, F = Ft2 + Fh2 + Fj3.

[0014] As a further aspect of the present invention, S5 is included after S4: The total dynamic force and component force data obtained from the solution are organized and output.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This method does not require disassembling the entire vehicle suspension structure. It only requires placing strain sensors on the spring surface and displacement sensors along the direction of shock absorber movement to carry out the test. There is no need to install multiple dedicated force sensors, which avoids damage to the original suspension structure, greatly simplifies the test installation process, and reduces the cost of test equipment and manual operation.

[0016] This method can be used to complete the test under the actual driving conditions of the vehicle, and can fully cover a variety of complex real vehicle conditions such as driving on bumpy roads, going over speed bumps, and turning. It solves the problems of traditional bench testing being unable to simulate the complex driving conditions of real vehicles and the large deviation between the test results and the actual force. The test data is closer to the force situation of the vehicle when it is running, and has higher engineering reference value.

[0017] This method fully considers the synergistic force relationship among the spring, buffer block, and shock absorber. It constructs separate calculation logics for the two states of the buffer block and the cap being in contact and not in contact, and fully incorporates three types of force components: the pure force of the spring, the force of the buffer block, and the damping force of the shock absorber. This avoids the result deviation caused by the omission of some force components in existing methods, and can accurately obtain the total dynamic force of the shock absorber acting on the vehicle body, effectively improving the accuracy of the test results.

[0018] This method can not only output the total dynamic force of the suspension damper, but also simultaneously obtain the dynamic changes of the pure force of the spring, the force of the buffer block, and the damping force of the damper. It can clearly present the force composition of the damper under different working conditions, and provide comprehensive and accurate data for vehicle chassis design, suspension parameter tuning and suspension structure optimization, thereby supporting the improvement of vehicle ride comfort, handling stability and NVH performance.

[0019] This testing method has a clear process and is highly practical. It can be adapted to the testing needs of suspension shock absorbers of various passenger vehicles, filling the current technical gap in the industry where the total dynamic force of the vehicle shock absorber can be accurately obtained without disassembling the suspension or using a dedicated force sensor. It has high value for promotion and application. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1This is a schematic diagram of the suspension damper and sensor layout structure involved in the present invention; Figure 2 This is a flowchart illustrating the overall process of the testing method of the present invention. Figure 3 This is a schematic diagram of the strain versus total dynamic force curve of the strain gauge sensor; Figure 4 A schematic diagram showing the relationship between damping force and velocity of a shock absorber. Figure 5 This is a schematic diagram showing the relationship between the compression of the buffer block and the applied force.

[0022] In the attached diagram: 1-Spring, 2-Buffer block, 3-Strain gauge sensor, 4-Cap, 5-Vibration damper, 6-Displacement sensor. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The present invention will be further explained below with reference to specific embodiments.

[0025] like Figure 1 As shown, the test objects involved in this invention include a spring 1, a buffer block 2, a strain gauge sensor 3, a clamp 4, a vibration damper 5, and a displacement sensor 6. The strain gauge sensor 3, as a strain detection component, is attached to the surface of the spring wire of the spring 1. The displacement sensor 6 is arranged along the axial movement direction of the vibration damper 5 and is used to collect real-time stroke data of the vibration damper 5. The clamp 4 is fixed to the end of the piston rod of the vibration damper 5 and moves with the extension and retraction of the vibration damper 5. During the compression stroke, it can contact and compress the buffer block 2.

[0026] like Figure 2 As shown in the figure, this embodiment provides a dynamic force testing method for suspension shock absorbers under vehicle operating conditions. Using a compact sedan as the test object, a vehicle condition inspection is conducted before testing to confirm that all suspension components are in good condition, without looseness or deformation, that the shock absorbers have no oil leaks, and that the springs are in normal elasticity. Simultaneously, strain gauge sensors 3, displacement sensors 6, a data acquisition instrument, calibration loading equipment, and an MTS test bench are prepared, ensuring that the equipment's metrological condition is qualified. The entire testing method is implemented through the following steps: S1: Vehicle Sensor Deployment Select the middle section of the spring wire with uniform stress on the spring 1 of the suspension as the pasting area. After cleaning the paint and oxide layer on the surface of this area, paste the strain gauge sensor 3 flatly on the area with uniform stress on the spring 1. Make sure to fix and protect the lead wire to ensure that the sensor will not fall off or have its signal interrupted due to vibration or scratches during vehicle operation.

[0027] Displacement sensors 6 are installed along the extension and retraction direction of the suspension damper 5. The two ends of the displacement sensors 6 are fixed to the vehicle body side and the suspension movement side respectively. The installation angle is adjusted so that the displacement detection direction is consistent with the axis direction of the damper 5, ensuring that the displacement acquisition value corresponds completely with the actual stroke of the damper.

[0028] Connect the signal output cables of strain gauge sensor 3 and displacement sensor 6 to the same data acquisition instrument, complete the power-on debugging of the equipment, set a unified sampling trigger mode, realize the synchronous acquisition of the time axis of strain signal and displacement signal, and ensure that the two sets of signals correspond one-to-one in the time domain.

[0029] S2: Precalibration and Feature Acquisition The calibration method was used to obtain the correspondence between the shock absorber stroke and the total spring force, Ft1. With the vehicle stationary, the suspension was subjected to graded loading, and the shock absorber stroke value and the corresponding strain gauge sensor 3 output value were recorded under each load level. Simultaneously, the total spring force under the corresponding stroke was calibrated. Finally, a correlation Ft1 between the strain gauge sensor deformation and the total dynamic force was established through fitting, forming a relationship as follows: Figure 3 The characteristic curves shown are shown.

[0030] The relationship between deformation and applied force of the suspension damper buffer block 2 was measured using bench testing. The buffer block 2 was clamped onto the bench fixture, and a uniform compression test was performed along the axial direction of the buffer block. The reaction force values ​​of the buffer block under different compression deformations were collected, and the corresponding curves of the buffer block compression and applied force were plotted. Figure 5 As shown.

[0031] The damping force and velocity curves of the core of vibration damper 5 were measured using an MTS test bench. Vibration damper 5 was mounted on the MTS electro-hydraulic servo test bench, and reciprocating excitation was performed simulating the actual working direction of the damper. The damping force output of the damper at different motion velocities was collected, and the corresponding curve of damping force versus motion velocity was plotted. Figure 4 As shown.

[0032] The above three sets of characteristic relationships provide basic parameters for subsequent calculation of dynamic forces in actual vehicles.

[0033] S3: Real-vehicle multi-condition dynamic test After completing sensor deployment and pre-load characteristic acquisition, dynamic testing of the actual vehicle under multiple operating conditions was conducted. The data acquisition device was set to continuous acquisition mode, and the vehicle was driven to complete various typical driving conditions in sequence. Data acquisition was maintained uninterrupted throughout the test, and strain and displacement signals under all conditions were stored synchronously.

[0034] The actual vehicle driving conditions include, but are not limited to: bumpy road driving conditions, where the vehicle travels at a constant speed along a set bumpy road section and the dynamic response of the suspension under continuous bumpy conditions is collected; speed bump driving conditions, where the vehicle passes through a standard speed bump perpendicularly at a set speed and the force changes at the moment of impact are collected; and steering driving conditions, where the vehicle performs steady-state steering and the lateral force and dynamic travel changes of the suspension are collected during the steering process.

[0035] S4: Dynamic Force Solution Based on the relationship between the acquired strain and displacement signals and the previously acquired characteristics, the component forces and the total dynamic force are calculated step by step: The method for determining the force and contact state of the buffer block is as follows: The actual stroke of the damper at the current moment is obtained based on the displacement signal, and the force Fh2 of the buffer block 2 is calculated by combining the deformation and force characteristic curve of the buffer block. At the same time, the contact state between the buffer block 2 and the end cap 4 of the damper 5 is determined according to the damper stroke: when the damper compression stroke does not reach the critical value of buffer block contact, the buffer block 2 is not in contact with the cap 4 and is in a free state, which is determined to be a non-contact state; when the damper compression stroke reaches or exceeds the critical value, the buffer block 2 contacts the cap 4 and produces compression deformation, which is determined to be a contact state.

[0036] The displacement signal is differentiated to obtain the real-time movement speed of the 5 cores of the shock absorber. Combined with the pre-acquired damping force versus speed curve of the shock absorber, the damping force value at the current speed is matched, and the damping force Fj3 of the shock absorber is calculated.

[0037] The total force Ft1 of the spring is obtained by combining the strain signal with the calibration relationship; the total force Ft1 of the spring is composed of the pure force Ft2 of spring 1 and the force Fh2 of buffer block 2, and is related to the displacement of the suspension damper.

[0038] When buffer block 2 is in an uncontacted state, the buffer block has no force output, and the pure force on the spring is equal to the total force on the spring, that is, Ft2=Ft1; When the buffer block 2 is in contact, the total force on the spring includes the reaction force contribution of the buffer block. Therefore, by subtracting the force of the buffer block from the total force, we can obtain the pure force on the spring: Ft2 = Ft1 - Fh2.

[0039] Total dynamic force superposition: When the buffer block 2 is not in contact with the cap 4, the total dynamic force of the suspension damper is composed of the pure force of the spring and the damping force of the damper, that is, F=Ft2+Fj3; When the buffer block 2 contacts the cap 4, the total dynamic force is composed of the pure force of the spring, the force of the buffer block and the damping force of the shock absorber, that is, F=Ft2+Fh2+Fj3.

[0040] Among them, total dynamic force can directly affect the vehicle's ride comfort, handling stability and NVH performance, and is a key prerequisite for chassis design, tuning and suspension optimization.

[0041] S5: Data Processing and Output The total dynamic force, the pure force of the spring, the force of the buffer block, and the damping force of the shock absorber are processed in the time domain. The dynamic force time domain variation curves under different working conditions are output. The peak force value, variation range and other characteristic data under each working condition are statistically analyzed. At the same time, the composition of each component force in the total dynamic force is presented. Finally, the complete test results are output to complete the entire test process.

[0042] This invention eliminates the need to disassemble the suspension and dedicated force sensors, making it convenient and low-cost. It can accurately obtain the total dynamic force and component forces of the shock absorbers under vehicle operating conditions, providing reliable data support for chassis tuning and suspension optimization.

[0043] This embodiment verifies the feasibility and high precision of the method, which can achieve accurate testing of the dynamic force of the shock absorber under the whole vehicle condition without disassembling the suspension. It can be widely used in the suspension development and tuning of various passenger vehicles.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the dynamic force of a suspension shock absorber under vehicle operating conditions, characterized in that, Includes the following steps: S1. Install strain sensors on the surface of the suspension springs and displacement sensors along the direction of motion of the shock absorber. S2. Pre-obtain the correspondence between the spring strain of the shock absorber and the total force of the spring, Ft1; pre-obtain the correspondence between the deformation of the buffer block and the applied force; pre-obtain the correspondence between the damping force of the shock absorber and the motion speed. S3. Under actual vehicle driving conditions, simultaneously collect the strain signal from the strain sensor and the displacement signal from the displacement sensor. S4. Calculate the force Fh2 of the buffer block based on the displacement signal and determine the contact state between the buffer block and the cap. The vibration damper velocity is obtained by filtering and differentiating the displacement signal, and the vibration damper damping force Fj3 is calculated by combining the relationship between the vibration damper damping force and the velocity. Based on the contact state of the buffer block, the pure force Ft2 of the spring is calculated by combining the total force Ft1 of the spring and the force Fh2 of the buffer block. The total dynamic force F of the shock absorber is obtained by superimposing the corresponding component forces according to the contact state of the buffer block.

2. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 1, characterized in that, In S1, the strain sensor is a strain gauge sensor, which is attached to the elastic deformation area of ​​the suspension spring; The detection direction of the displacement sensor is consistent with the extension and retraction direction of the suspension damper.

3. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 2, characterized in that, In S1, both the strain sensor and the displacement sensor are connected to the data acquisition instrument to achieve synchronous acquisition of strain signals and displacement signals.

4. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 1, characterized in that, In S2, the relationship between the shock absorber stroke and the total force on the spring, Ft1, is obtained through calibration. The relationships between the deformation of the buffer block and the applied force, and between the damping force of the shock absorber and the motion speed, were obtained through bench testing.

5. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 1, characterized in that, In S2 and S3, bench damping force testing, bench spring force calibration, buffer block force testing, and vehicle operating conditions are combined to dynamically calculate the composition and magnitude of various forces in the suspension damper.

6. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 1, characterized in that, In S4, the contact state between the buffer block and the cap is determined based on the damper stroke corresponding to the displacement signal: When the buffer block is in a free state and not in contact with the cap, it is determined to be in a non-contact state; When the buffer block comes into contact with the card cap, it is determined to be in a contact state.

7. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 6, characterized in that, In S4, the pure force value Ft2 of the spring is calculated based on the contact state, specifically as follows: When the buffer block is in an uncontacted state, Ft2 = Ft1; When the buffer block is in contact, Ft2 = Ft1 - Fh2.

8. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 7, characterized in that, In S4, the total dynamic force F is superimposed in the following way: When the buffer block is in an uncontacted state, F = Ft2 + Fj3; When the buffer block is in contact, F = Ft2 + Fh2 + Fj3.

9. The method for testing the dynamic force of a suspension damper under vehicle operating conditions according to claim 1, characterized in that, S5 is included after S4: The total dynamic force and component force data obtained from the solution are organized and output.

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