Decoupled measurement method and system for fixed caliper drag chatter characteristics

Abstract

The application belongs to the technical field of vehicle brake system testing, and provides a fixed brake caliper drag oscillation characteristic decoupling measurement method and system. First, according to the time domain drag torque signal, the direct current component of the torque signal is extracted by integral method to represent the sealing ring return characteristic. Then, according to the time domain drag torque signal, the alternating current component of the torque signal is extracted by residual analysis to represent the dynamic response of the brake caliper to the brake disc geometric runout. Finally, whether the hydraulic sealing return is poor is determined according to the direct current component; the brake disc precision risk and failure mode are determined according to the drag fluctuation amplitude and coupling sensitivity factor; and the single drag torque average is disassembled into the sealing ring constant component and the geometric fluctuation component, so that the engineers can clearly distinguish whether the fault source is the hydraulic sealing system (formula / slot) or the mechanical structure system (stiffness / tolerance).

Description

Technical Field

[0001] This invention belongs to the field of vehicle braking system testing technology, and particularly relates to a decoupled measurement method and system for the drag and vibration characteristics of fixed brake calipers. Background Technology

[0002] Fixed brake calipers lack dynamic compensation capabilities. When the brake disc experiences slight axial oscillation or disc thickness variation (DTV), the brake disc surface will periodically interfere and scrape against the friction pads, resulting in brake drag. Existing brake drag detection methods and standards typically use the time-domain averaging method for evaluation.

[0003] Existing average evaluation methods treat drag torque as a scalar, which cannot analyze the dynamic characteristics of the torque signal and cannot achieve decoupled measurement of constant and fluctuating components. When faced with brake shudder or excessive drag, engineers lack quantitative evidence to determine the root cause of the problem. This makes it difficult to determine during product development and rectification whether to optimize the material and groove design of the sealing ring or to adjust the stiffness characteristics of the caliper bracket to accommodate brake disc deformation by making concessions. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a decoupled measurement method and system for the drag and vibration characteristics of a fixed brake caliper. This invention decomposes the single drag torque mean into a constant component of the sealing ring and a geometric fluctuation component, enabling engineers to clearly distinguish whether the source of the fault is the hydraulic sealing system or the mechanical structure system.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper, comprising: Obtain the time-domain drag torque signal of the fixed brake caliper; Based on the time-domain drag torque signal, the DC component of the torque signal is extracted by integration to characterize the return characteristics of the sealing ring; Based on the time-domain drag torque signal, the AC component of the torque signal is extracted through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc; the drag fluctuation amplitude is determined based on the AC component; a three-dimensional thermal-vibration-drag characteristic map is constructed based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; the dangerous areas that cause the drag fluctuation amplitude to exceed the threshold are identified using the thermal-vibration-drag three-dimensional characteristic map; and the coupling sensitivity factor is determined based on the ratio of the drag fluctuation amplitude to the thickness difference change amplitude within one revolution of the brake disc. The DC component is used to determine whether there is a problem with the hydraulic seal return; the drag fluctuation amplitude and coupling sensitivity factor are used to determine the brake disc accuracy risk and failure mode.

[0006] Furthermore, the time-domain drag torque signal is converted into an angular domain signal, and the angular domain signal is separated into DC and AC components through a mathematical model.

[0007] Furthermore, the angular domain signal within one rotation cycle is integrated and averaged to obtain the DC component, which characterizes the piston seal's return capability. If the DC component exceeds a set threshold, it is determined to be a hydraulic seal return failure, regardless of the brake disc's accuracy. The DC component represents the constant drag torque component caused by the seal. : ; in, This is the constant dragging torque component caused by the sealing ring; This is the instantaneous drag torque function in the angular domain. For integration variables; This refers to the rotation angle of the brake disc.

[0008] Furthermore, the AC component characterizes the periodic interference caused by brake disc end face runout or thickness difference. The residual after subtracting the DC component from the original signal: ; in, This is the angular domain signal within one rotation cycle; This is the DC component.

[0009] Furthermore, the drag fluctuation amplitude is the peak-to-peak value of the drag torque fluctuation within one revolution of the brake disc: .

[0010] Furthermore, the coupling sensitivity factor for: ; in, This is the coupling sensitivity factor; This is to reduce the amplitude of fluctuations; This represents the measured thickness difference variation amplitude within one revolution of the brake disc. Current test temperature The compression modulus correction factor for the lower friction plate.

[0011] Furthermore, the construction of the thermal-vibration-drag three-dimensional characteristic map includes: constructing a three-dimensional characteristic surface with the brake disc temperature as the X-axis, the brake disc end face runout as the Y-axis, and the drag fluctuation amplitude as the Z-axis.

[0012] Furthermore, if the AC component amplitude is greater than the threshold, the brake caliper is deemed to have a risk of vibration under the current operating conditions; if the AC component amplitude is greater than or equal to the preset amplitude value and the coupling sensitivity factor is greater than or equal to the preset sensitivity value, the caliper structure stiffness design is deemed unreasonable, making it overly sensitive to disc deformation; if the AC component amplitude is greater than or equal to the preset amplitude value but the coupling sensitivity factor is less than the preset sensitivity value, the brake disc processing quality is deemed to be faulty, while the caliper itself is deemed to be qualified; if the AC component amplitude is less than the preset amplitude value but the coupling sensitivity factor is greater than or equal to the preset sensitivity value, the seal is deemed to be aging or lubrication failure.

[0013] Secondly, the present invention also provides a decoupled measurement system for the drag and jitter characteristics of a fixed brake caliper, comprising: The data acquisition module is configured to acquire the time-domain drag torque signal of the fixed brake caliper. The DC component decoupling module is configured to: extract the DC component of the torque signal by integration based on the time-domain drag torque signal to characterize the return characteristics of the sealing ring; The AC component decoupling module is configured to: extract the AC component of the torque signal from the time-domain drag torque signal through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc; determine the drag fluctuation amplitude based on the AC component; construct a three-dimensional thermal-vibration-drag characteristic map based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; identify the danger zone that causes the drag fluctuation amplitude to exceed the threshold using the thermal-vibration-drag three-dimensional characteristic map; and determine the coupling sensitivity factor based on the ratio of the drag fluctuation amplitude to the thickness difference change amplitude within one rotation of the brake disc. The measurement and judgment module is configured to: determine whether there is a problem with the hydraulic seal return based on the DC component; and determine the brake disc accuracy risk and failure mode based on the drag fluctuation amplitude and coupling sensitivity factor.

[0014] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the decoupling measurement method for the drag jitter characteristics of the fixed brake caliper described in the first aspect.

[0015] Fourthly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the steps of the decoupling measurement method for the drag jitter characteristics of the fixed brake caliper described in the first aspect.

[0016] Fifthly, the present invention also provides a computer program product, the computer program product comprising a computer program, which, when executed by a processor, implements the steps of the decoupling measurement method for the drag and jitter characteristics of the fixed brake caliper described in the first aspect.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention first extracts the DC component of the time-domain drag torque signal through integration to characterize the return characteristics of the sealing ring; then, it extracts the AC component of the torque signal through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc; the drag fluctuation amplitude is determined based on the AC component; a three-dimensional thermal-vibration-drag characteristic map is constructed based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; and the three-dimensional thermal-vibration-drag characteristic map is used to calibrate the factors causing the drag fluctuation amplitude. Dangerous areas exceeding thresholds; determining the coupling sensitivity factor based on the ratio of drag fluctuation amplitude to the thickness difference change amplitude within one rotation of the brake disc; finally, determining whether there is hydraulic seal return failure based on the DC component; judging the brake disc accuracy risk and failure mode based on drag fluctuation amplitude and coupling sensitivity factor; decomposing the single drag torque mean into a constant component of the seal ring and a geometric fluctuation component, enabling engineers to clearly distinguish whether the source of failure is the hydraulic sealing system (change formula / groove) or the mechanical structure system (change stiffness / tolerance).

[0018] 2. The present invention and the proposed sensitivity factor can directly quantify the sensitivity of fixed calipers to disc deformation without relying on subjective evaluation, thus solving the problem that NVH problems are difficult to predict at the component bench stage.

[0019] 3. By constructing a three-dimensional thermal-vibration-drag map, this invention not only examines the condition of new discs at room temperature, but also covers high-temperature thermal deformation conditions, effectively avoiding the problem of missing detection of abnormal vibrations in high-performance vehicles on the track or after continuous braking. Attached Figure Description

[0020] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0021] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram comparing the signal waveforms of Embodiment 1 of the present invention; Figure 3 This is the thermal-vibration-hysteresis three-dimensional mapping map of Embodiment 1 of the present invention; Figure 4This is a flowchart illustrating the measurement steps and data analysis of Embodiment 2 of the present invention; Figure 5 This is a flowchart of the processing in Embodiment 3 of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] Example 1: As the automotive industry continues to demand higher braking performance from vehicles, fixed-piston brake calipers are widely used in the braking systems of high-end passenger cars and high-performance sports cars due to their excellent structural rigidity, extremely low hydraulic hysteresis, and direct pedal force feedback. Unlike common floating calipers, fixed-piston brake calipers have their housings rigidly connected to the steering knuckle or suspension by bolts, and their structure does not include floating pins or sliding guide mechanisms to eliminate axial displacement of the brake disc.

[0025] However, while this high-rigidity fixed mounting method brings performance advantages, it also introduces significant geometric sensitivity issues. During actual vehicle operation, brake discs inevitably experience side run-out (SRO) or thermal coning due to high temperatures. Because fixed brake calipers lack adaptive compensation capabilities, when the brake disc experiences even slight axial oscillations or thickness changes, the brake disc surface will periodically interfere and scrape against the friction pads, thus causing brake drag.

[0026] Existing brake drag detection methods and standards typically employ the time-domain averaging method for evaluation. This involves measuring and calculating the average drag torque over a period of time under specific speed and pressure release conditions. This traditional detection method has significant technical limitations, primarily in the following aspects: Existing average evaluation methods treat drag torque as a scalar, failing to analyze the dynamic characteristics of the torque signal. Physically, the residual drag torque of a fixed brake caliper is actually composed of two independent coupled physical components: first, a constant component (DC term), mainly caused by insufficient return capability of the piston seal or piston jamming, manifesting as continuous constant resistance; second, a fluctuating component (AC term), mainly caused by the interference between the brake disc's geometric error (SRO / DTV) and the rigidity of the brake caliper structure, manifesting as periodic fluctuations with changes in wheel angle.

[0027] Average values ​​alone cannot distinguish between the two drastically different failure mechanisms mentioned above. For example, the average drag torque obtained from the tests is the same, but... The two samples may have completely different actual operating conditions: Operating condition A: Torque is constant at 2 This primarily affects fuel economy (fuel consumption / electricity consumption) and friction plate wear. Operating condition B: Torque at 0... Up to 4 The values ​​fluctuated wildly between these values ​​(the mean remained at 2). This low-frequency, large-amplitude torque fluctuation is directly transmitted to the suspension system, inducing brake jerking or low-frequency vibration of the vehicle body, which seriously affects the NVH (Noise, Vibration, and Harshness) performance of the entire vehicle.

[0028] Because current technology cannot achieve decoupled measurement of the two components mentioned above, engineers lack quantitative evidence to determine the root cause when faced with issues such as excessive brake shudder or drag. This makes it difficult to determine during product development and rectification whether to optimize the material and groove design of the sealing ring (for the constant component) or to adjust the stiffness characteristics of the caliper bracket to accommodate brake disc deformation through "concession" (for the fluctuating component).

[0029] To solve at least one of the above problems, such as Figure 1 As shown, this embodiment provides a decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper, including: S1. Construct a multi-physics synchronous acquisition and testing platform (rotational speed synchronization and domain transformation): The raw time-domain signal acquired by the dynamic torque sensor Synchronization with the angle encoder signal is performed. An interpolation algorithm maps the time-dependent signal to an angle-domain signal with the brake disc rotation angle as the independent variable. To eliminate the influence of speed fluctuations on test results, and to ensure that subsequent integration and fluctuation analysis are strictly based on the geometric position of the brake disc, spatial alignment is achieved.

[0030] The fixed brake caliper and brake disc to be tested are mounted on the braking inertia test bench, and the following high-precision sensor system is configured: S1.1 Dynamic Torque Acquisition Unit: A high-frequency dynamic torque sensor is used to connect to the brake caliper mounting bracket, and the sampling rate is set to [value missing]. It is used to capture transient drag torque fluctuations.

[0031] S1.2, Geometric Error Monitoring Unit: High-resolution eddy current displacement sensors are symmetrically arranged on both sides of the brake disc to monitor in real time the disc thickness variation (DTV) and end face runout of the brake disc as the angle changes.

[0032] S1.3, Thermal monitoring unit: Install an infrared thermal imager or multi-point thermocouples to monitor the temperature field distribution of the brake disc and friction pads in real time.

[0033] S1.4 Synchronous Trigger Mechanism: By using a high-resolution angle encoder as the main shaft signal, strict alignment of torque, displacement, and temperature signals in the angular domain is ensured.

[0034] S2. Signal decoupling model based on angular domain transform (signal decoupling operation): The acquired time-domain drag torque signal Convert to angular domain signal ,in, The angle of rotation of the brake disc ( The signal is separated into two orthogonal components, direct current (DC) and alternating current (AC), using a mathematical model. The physical properties of the original signal are then decoupled using the following mathematical model: S2.1 Calculate the DC component to characterize the return performance of the sealing ring.

[0035] Separate the DC component (sealing ring characteristics) for the angular domain signal within one rotation cycle. By performing integral averaging, the constant drag torque component caused by the sealing ring is obtained. This characterizes the piston seal's return capability. If the DC component... Exceeding the set threshold (e.g., 1) The result was determined to be a problem with the hydraulic seal return, and was unrelated to the accuracy of the brake disc.

[0036] Define the constant drag torque component caused by the sealing ring. For the brake disc to rotate for one complete cycle ( The integral mean of the internal drag torque, which eliminates the interference of periodic fluctuations, purely represents the constant resistance caused by insufficient piston seal return distance or piston jamming, and its expression is: ; in, The constant drag torque component caused by the sealing ring (unit: N) m); This is the instantaneous drag torque function in the angular domain. The variable is the integral variable, representing the rotation angle (unit: ...). ); This refers to the rotation angle of the brake disc.

[0037] S2.2 Extract the AC component to characterize geometric interference and structural stiffness.

[0038] Separate the AC components (geometric interference characteristics), calculate the residual between the original signal and the DC component, and the criterion is... Characterizes periodic interference caused by brake disc end face run-out or thickness difference (DTV).

[0039] Define AC components The residual after subtracting the DC component from the original signal represents the torque fluctuation caused by the periodic impact of the brake disc geometric error (SRO / DTV) on the friction pads, i.e.: ; To quantify the intensity of brake jitter (Judder), the drag fluctuation amplitude is further defined. ,Right now: ; in, Peak-to-peak value of drag torque fluctuation during one revolution of the brake disc (unit: ).

[0040] S3. Calculate the stiffness-susceptibility factor: To evaluate the incompatibility or sensitivity of fixed brake calipers to brake disc geometric errors, a dimensionless or normalized coupling sensitivity factor is constructed. This factor incorporates the temperature characteristics of the friction pads to isolate the influence of material properties and solely evaluate the coupling effect between the caliper's structural stiffness and geometric errors. It is: ; in, This is the coupling sensitivity factor; a higher value indicates a worse NVH robustness of the system. The measured thickness difference variation within one revolution of the brake disc (unit: ); Current test temperature Correction factor for the compressive modulus of the lower friction plate (dimensionless, range of values) This is used to correct the problem of structural interference caused by the softening of friction materials due to high temperatures.

[0041] S4. Construct a three-dimensional characteristic map of "thermal-vibration-hysteresis" (comprehensive criteria and output): Perform multi-condition scanning tests. With the brake disc temperature (Temperature) as the X-axis, the brake disc run-out (Run-out / DTV) as the Y-axis, and the amplitude of the AC component separated in step S2 as the Z-axis, construct a three-dimensional characteristic surface. Through this atlas, calibrate the dangerous area that causes the amplitude of the AC component to exceed the vehicle's NVH threshold (such as 2N m), so as to guide the design of the caliper bracket stiffness or the formulation of the brake disc machining tolerance. For example, as shown in , for the NVH (noise, vibration, and harshness) threshold determination, if the amplitude of the AC component

[0042] (empirical threshold), it is determined that there is a risk of jitter for this brake caliper under the current working conditions. For failure mode localization, if the amplitude of the AC component Figure 2 is high (greater than or equal to the preset amplitude value) and the coupling sensitivity factor is high (greater than or equal to the preset sensitivity value), it is determined that the caliper structure stiffness design is unreasonable and is too sensitive to the disc surface deformation; if the amplitude of the AC component is high but the coupling sensitivity factor is low (less than the preset sensitivity value, only due to excessive input DTV), it is determined that there is a problem with the brake disc machining quality and the caliper itself is qualified; if the amplitude of the AC component is low (less than the preset amplitude value) but the coupling sensitivity factor is high, it is determined that the sealing ring is aged or the lubrication has failed. Specifically, the failure characteristics of the sealing ring correspond to high DC and low fluctuation ( dominant);

[0043] The solid line in indicates that when the sealing ring has poor return, the drag torque shows an overall translational lift (such as remaining constant at Figure 2 ), but the waveform is relatively flat. This characteristic confirms that the DC component ( ) can independently characterize the piston return performance of the hydraulic system and is not affected by the rotational position of the brake disc. The brake disc deformation characteristics correspond to high AC and strong sine ( dominant); The dashed line in Figure 2 indicates that when there is a brake disc thickness difference (Disc Thickness Variation, DTV) or run-out, the drag torque shows a severe periodic sine oscillation (with a large peak-to-valley difference), but the average value may not be high. This characteristic confirms that the AC component ( The interference that sensitively reflects the geometric precision of the disk surface is the direct cause of low-frequency jitter. A comparison of the solid and dashed lines shows that the two failure modes have drastically different mathematical forms in the time-domain waveform (flat vs. fluctuating), proving that the DC / AC signal separation algorithm proposed in this embodiment can effectively distinguish between soft faults (sealing / lubrication problems) and hard faults (structural / machining precision problems), avoiding misjudgments caused by traditional methods that only consider the maximum torque value.

[0044] like Figure 3 As shown, the three-dimensional mapping of heat-vibration-drag demonstrates the coupling amplification effect of temperature and DTV (difference in brake disc thickness) on the vibration amplitude. Figure 3 This study reveals that brake judder is not a simple linear response to DTV (difference in brake disc thickness), but rather a nonlinear, strongly coupled physical process significantly regulated by temperature. Specifically, in the low-temperature, low-DTV region (blue safe zone), the judder amplitude changes gradually. However, once it enters the high-temperature, high-DTV region (red high-risk zone), the combined effects of thermal deformation and changes in material properties cause temperature to act as an amplifier, resulting in an exponential and rapid increase in judder amplitude that instantly exceeds the NVH (noise, vibration, and harshness) failure threshold (2.0 Nm). This confirms the necessity of introducing a temperature correction coefficient in this embodiment, meaning that only through multidimensional decoupled measurement can we accurately identify those products that are qualified under cold conditions but will experience thermal-vibration coupling failure under high-temperature conditions.

[0045] Example 2: Building upon Example 1, this example provides a method for troubleshooting and optimizing vibration in a high-performance four-piston fixed brake caliper based on thermo-mechanical coupling decoupling. This example aims to demonstrate how the decoupling measurement method for the drag vibration characteristics of fixed brake calipers proposed in this invention can solve the abnormal vibration problem of a high-performance four-piston fixed brake caliper under high-temperature conditions. Traditional methods often struggle to distinguish between the seal return force and the resistance caused by disc geometric errors. However, this example achieves precise fault location by separating the DC and AC components.

[0046] S1. Experimental Subjects and Test Environment Setup: High-performance sports car-specific opposed four-piston fixed brake calipers and matching drilled and ventilated brake discs were selected as test samples. The samples were tested after the initial break-in period and the initial cold-state thickness difference (DTV) of the brake discs was [value missing]. In this state, it is installed on a device equipped with a non-contact eddy current displacement sensor (for monitoring DTV (brake disc thickness difference) and end face runout) and a sampling frequency of not less than The high-precision braking inertia test was conducted on a high-frequency dynamic torque sensor.

[0047] S2. Measurement steps and data analysis, such as Figure 4 As shown: S2.1 Signal decoupling under reference operating conditions (cold state test): At room temperature ( In this environment, control the brake disc to Rotational speed simulation of low-speed following conditions is used to collect drag torque under non-braking conditions and measure the raw signal. The arithmetic mean is Subsequently, the original signal was decomposed in the time and frequency domain using the signal processing algorithm of this invention to extract the DC component representing the return resistance of the sealing ring. for And the AC component representing the amplitude of jitter fluctuations. for (Peak-to-peak value); This result indicates that under cold conditions Extremely low and If the value is within the normal range, it indicates that the caliper piston return function is normal and that the caliper is functioning correctly. The system is insensitive to minute DTV (brake disc thickness difference) and is therefore in a safe zone.

[0048] S2.2 Thermal coupling excitation test (simulating extreme downhill conditions): Performing 15 consecutive braking operations with a deceleration of 0.4g caused the surface temperature of the brake disc to rise rapidly to [temperature value missing]. Subsequently, thermal imaging and displacement sensors detected significant "thermal disc deformation" of the brake disc due to high-temperature thermal stress, causing the equivalent runout at the disc edge to change from the initial value. surge to After releasing the brake pedal, record the residual drag torque waveform. It was found that the original torque reading was... to It oscillates violently and exhibits typical high-frequency, large-amplitude sine wave characteristics, with its arithmetic mean measured as follows: .

[0049] S2.3 Multidimensional Feature Decoupling and Sensitivity Analysis: The sealing characteristics were calculated by performing a second decoupling operation on the high-temperature data. for (Due to the thermal expansion of the sealing ring and the change in brake fluid viscosity compared to the cold state) A slight increase (which is a normal physical phenomenon), and the vibration characteristics Gundam It far exceeds the objective evaluation standard (threshold) for vehicle NVH. Furthermore, the coupling sensitivity factor of this invention is introduced. Calculations revealed that, at temperatures ranging from Rise to During the process, the jitter amplitude increases non-linearly, indicating that the system has entered the strong thermal-vibration coupling region.

[0050] S3. Fault Judgment Comparison and Optimization Implementation: S3.1 Risk of misjudgment in traditional methods: If only the traditional national standard method is used to measure the average drag torque ( Engineers are highly likely to misdiagnose this as a piston return defect (due to the high value). Based on this misdiagnosis, subsequent corrective measures often mistakenly focus on optimizing the chamfering of the rectangular seal groove or replacing the seal with a low-modulus seal. This not only fails to solve the problem but may also increase the brake pedal travel due to excessive return.

[0051] S3.2, Precise Judgment: Decoupling analysis reveals that the dominant factor in the failure is... (Percentage) ), rather than .

[0052] S3.3, Physical Mechanism Diagnosis: Although the brake disc occurred Thermal deformation, but Only This indicates that the piston itself has done its best to return to its original position. Huge AC fluctuations ( This indicates that the rigidity of the bridge structure of the fixed caliper is too large, and it cannot "follow" the thermal deformation of the brake disc in the lateral direction, resulting in hard interference between the caliper and the disc surface during rotation (Clamping Effect).

[0053] S3.4 Judgment Conclusion: The fault attribute is hard interference caused by the mismatch between structural stiffness and thermal deformation, which belongs to the structural design fault category, rather than the hydraulic component functional fault.

[0054] S3.5 Optimization Measures and Verification: Based on the above assessment, we abandoned the modification of the sealing ring and instead implemented the following structural optimization method: Structural optimization method 1: Fine-tuning the caliper mounting bracket. While ensuring braking strength, the mounting hole positions are topologically optimized by introducing micron-level lateral flexibility to absorb some thermal deformation. Structural optimization method 2: Upgrading the brake disc heat treatment process. A stress-relieving annealing process is added. The amount of thermal deformation is controlled within Within.

[0055] S3.6 Verification results of structural optimization: After retesting, Maintain at (Ensuring pedal feel), but from Significantly reduced This successfully eliminated the high-temperature braking vibration phenomenon of the entire vehicle, verifying the effectiveness of the decoupling analysis method of this invention.

[0056] Example 3: Based on Example 1, this example provides a method for diagnosing and optimizing the cold-state vibration of brake calipers in new energy vehicles based on friction interface characteristics, including: For new energy vehicles equipped with high-performance six-piston fixed brake calipers, a noticeable low-frequency cold jerking accompanied by abnormal noise is observed during the first braking process after being parked overnight. Although this phenomenon diminishes with subsequent driving, troubleshooting methods based on traditional experience fall into a trap: with the measured brake disc thickness difference (DTV) being only 6μm (better than the national standard) and the end face runout being within acceptable limits, existing technical means cannot explain the cause of the jerking. Consequently, the fault is mistakenly attributed to improper modal matching of the suspension system, resulting in subsequent rectification work on the stiffness of the control arm bushing being time-consuming, labor-intensive, and ultimately ineffective.

[0057] The decoupling measurement method described in this invention was used to perform cold bench testing on the faulty sample, and the original total drag torque signal was monitored ( It exhibits significant periodic fluctuation characteristics, with its peak fluctuation reaching 5.0N. m, initially confirms the existence of the shaking phenomenon. For example... Figure 5 As shown, the method includes: S1. Regarding the fault phenomenon of cold braking vibration (without noise), traditional testing shows that the brake disc thickness difference (DTV) is only... The result falls within the acceptable range. This leads to a common misjudgment, based on traditional experience, that the problem is insufficient stiffness of the suspension system. However, this process avoids this pitfall and instead employs the decoupling diagnostic technique of this invention for in-depth troubleshooting.

[0058] S2. Through core decoupling diagnosis, the signal is decomposed into two dimensions: DC and AC. The results show the DC component ( The system is stable, eliminating mechanical and hydraulic jamming; while the AC component ( )Gundam Assuming the brake disc geometry is within acceptable limits, this directly pinpoints the root cause of the fault as "uneven friction coefficient of the disc surface".

[0059] S3. In-depth analysis of the microscopic causes revealed that the low-metal brake pads underwent electrochemical corrosion in a high-humidity environment. Corrosion products transferred to the brake disc surface, forming a non-uniform "transfer film," causing fluctuations in friction and resulting in brake torque variation (BTV). To address this, a dual physical and chemical improvement strategy was implemented: firstly, 3%-5% zirconium silicate was added as an abrasive to actively polish and remove the non-uniform transfer film; secondly, modified phenolic resin was used to improve hydrophobicity, cutting off the electrochemical corrosion path at its source.

[0060] S4. Verification results show that the jitter amplitude ( ) down to The noise level decreased by 84%, and the subjective driving experience was good with no noise. This case strongly demonstrates that the present invention can effectively solve hidden faults that cannot be identified by measuring DTV alone by distinguishing between mechanical resistance and friction fluctuations.

[0061] Further signal decoupling analysis using algorithms was performed to separate the DC component of the sealing characteristics ( Stable at 1.2N m, which directly indicates that the piston seal has not undergone cryogenic hardening or jamming, and its return function is in a completely normal state; in stark contrast, the AC component representing the vibration characteristics (m) Amplitude up to 3.8N m, and the frequency characteristics are mainly concentrated in the first and second orders of wheel rotation frequency.

[0062] Based on the above data, physical logic deduction is performed. Assuming that geometric quantities such as brake disc thickness difference (DTV) are within acceptable limits, and combined with... Verified normal piston contact pressure ( According to the braking torque formula: ; It can be seen that this leads to high amplitude The only variable is no longer geometric deformation, but the coefficient of friction. The distribution is uneven in the circumferential direction of the brake disc.

[0063] S5. Physical Mechanism Diagnosis (Root Cause Analysis): First, this embodiment clearly defines the nature of the fault, classifying it as Brake Torque Variation (BTV) induced by the friction pair interface. This is fundamentally different from the geometric hard interference based on the physical deformation of components in Embodiment 2. Through the decoupling analysis of this invention, macroscopic structural deformation factors are successfully eliminated, and the core of the problem is precisely locked onto the microscopic characteristics of the friction interface.

[0064] Secondly, in-depth causal analysis revealed that during long-term parking in a humid environment, the low-metal, high-friction coefficient brake pads in this vehicle underwent slight electrochemical corrosion and adhesion between their internal metal components and the cast iron brake disc surface. This microscopic interaction resulted in the formation of a non-uniform transfer film on the brake disc surface, which is difficult to detect with the naked eye. It is this non-uniform film that directly disrupts the consistency of the friction coefficient in the circumferential direction.

[0065] Finally, regarding system sensitivity, because high-performance six-piston fixed brake calipers lack the pin clearance buffer of traditional floating calipers, their high-rigidity body structure exhibits extremely high transmission efficiency for minute changes in disc friction. Therefore, minute fluctuations in the coefficient of friction caused by uneven distribution of the transfer film ( The jitter component was not absorbed by the system damping, but was instead amplified as a high-amplitude jitter characteristic component. This ultimately triggered noticeable cold-state vibrations in the vehicle body.

[0066] S6. Optimization measures: Based on the determination of friction coefficient fluctuation, instead of changing the expensive caliper aluminum alloy housing mold, the friction material formula can be adjusted specifically: To address the issue of uneven friction surfaces, this embodiment first introduces a physical cleaning mechanism, namely, adding 3% to 5% micron-sized zirconium silicate abrasive particles (Mohs hardness 6.5) to the brake pad friction material formulation. Utilizing the slight polishing effect generated by these hard particles during braking, the non-uniform transfer film adhering to the brake disc surface can be dynamically and continuously removed, thereby ensuring that the disc surface friction characteristics remain consistent and eliminating the torque fluctuation source that induces vibration at a physical level.

[0067] Meanwhile, to fundamentally suppress adhesion, this solution further optimizes the binder system. By adjusting the modification ratio of phenolic resin, the hygroscopicity of brake pads under low-temperature and high-humidity conditions is significantly reduced. This measure effectively blocks the media conditions for electrochemical corrosion, greatly reduces the tendency for static adhesion when the vehicle is stationary, and prevents disc surface damage and transfer film accumulation caused by corrosion adhesion.

[0068] S7. Verification result: Brake pads with an optimized formula were retested: First, the effectiveness of the optimization scheme was quantitatively verified by comparing bench test data before and after the improvement. Test results show that the sealing characteristic component ( It remains at 1.2N m remains unchanged, indicating that the physical adjustment of the brake pad formula did not negatively affect the piston movement resistance and the basic characteristics of the caliper system; at the same time, the vibration characteristic component, which reflects the severity of the fault, ( The magnitude of the amplitude has undergone a qualitative change, from the original 3.8N. m drops sharply to 0.6N m, from a data perspective, proves that the source of torque fluctuation has been effectively cut off.

[0069] Secondly, the improvements at the data level are highly consistent with the subjective evaluation results of the actual vehicle. Under the cold-state condition of the first braking in the morning, the previously frequent vibration phenomenon has completely disappeared, and the introduction of abrasive particles has not led to an increase in braking noise. This indicates that the improvement solution has successfully taken into account the NVH (noise, vibration and harshness) comfort requirements of the whole vehicle while solving the vibration problem.

[0070] Finally, the successful application of this embodiment profoundly demonstrates the technical advantages of the decoupling measurement method described in this invention. It proves that this method can not only effectively diagnose thermal-structural overt faults based on geometric deformation, but also possesses the ability to delve into the microscopic level and accurately diagnose cold-material interface friction faults, exhibiting strong universality and accuracy, and possessing extremely high engineering application value.

[0071] Example 4: Based on Example 1, this example provides a method for diagnosing and optimizing the structure of large-size multi-piston calipers with "dragging and uneven wear" based on piston damping consistency analysis, focusing on faults caused by machining tolerances and assembly consistency.

[0072] For a high-end SUV equipped with six-piston fixed brake calipers, there was an occasional low-frequency creeping sound and slight body vibration during low-speed coasting or when the brake pedal was released. Traditional testing methods were stuck after confirming that the brake disc thickness difference (DTV) was acceptable, ruling out brake pad corrosion (non-chemical corrosion) and normal friction coefficient (non-thermal fade). This led the engineering team to misjudge the problem as a design defect in the brake pad chamfer. However, repeated modifications to the chamfer failed to solve this persistent issue.

[0073] The method of this invention is used to decouple and analyze the drag torque signal, focusing on the DC component during the braking release phase. ) characteristics. Analysis revealed that after hydraulic release Instead of smoothly returning to zero according to the standard curve, it exhibits a step-like or long-tailed hysteresis residue, and its value remains at a certain level for a long period of time. Left and right, far exceeding The standard value; this abnormal feature reveals that there is an asynchronous return phenomenon of the six pistons inside the caliper, that is, some pistons (especially the guide end) are delayed in returning due to excessive resistance, which causes the brake pads to be loosened in a large area, but local areas are still pressed on the brake disc by residual pressure.

[0074] Further analysis of the communication components ( It was found that the signal contained low-amplitude fluctuations highly correlated with wheel speed. Based on the analysis of the DC component, it was inferred that this fluctuation was caused by uneven piston return, resulting in a tapered contact between the brake pads and the brake disc. This non-parallel contact caused uneven wear of the brake pads, which in turn generated unstable frictional torque fluctuations, ultimately inducing vibration and abnormal noise at low vehicle speeds.

[0075] Based on the diagnostic clue of asynchronous piston return, a coordinate measuring machine was used to perform precision dimensional inspection on the caliper cylinder. The inspection results showed that there was a small but critical difference in the machining tolerance of the seal grooves of the piston mounting holes on the inner and outer sides of the caliper, thus accurately pinpointing a geometric deviation problem at the manufacturing process level.

[0076] Further analysis of the failure mechanism revealed that the chamfer size of the inner lower sealing groove was too small, causing the rectangular sealing ring (Seal) assembled at this location to be over-compressed, which significantly weakened the elastic potential energy required for the sealing ring to undergo roll-back deformation. This structural defect turned the piston into a "lazy piston" with roll-back failure, causing the brake pads to remain in a state of slight drag in this area for a long time, ultimately inducing low-frequency vibration.

[0077] To address the identified manufacturing defects, structural optimization of the caliper cylinder block machining process was implemented. By strictly correcting the chamfer dimensional tolerances of the sealing groove, the geometric deviations that caused the seal ring to be over-compressed were eliminated at the physical level, ensuring that the seal ring had sufficient deformation space to generate standard roll-back force. This fundamentally resolved the mismatch between structural design and manufacturing.

[0078] Furthermore, to further enhance the system's robustness and compensate for potential tolerance risks, a low-friction coefficient diamond-like carbon (DLC) coating technology was introduced onto the piston surface. This surface treatment process significantly reduces the mechanical resistance of the piston within the cylinder, assisting the piston to return to its original position more smoothly after hydraulic release, effectively preventing piston retention caused by excessive resistance, and completely resolving the vibration problem caused by micro-drag.

[0079] The improved braking system was verified using the detection method of this invention, and the results showed that the drag torque signal characteristics had undergone a fundamental change. The DC component during the brake release phase ( The curve changed from its previous abnormally sluggish shape to a smooth linear decline, and the residual resistance value was successfully reduced to... Completely satisfies less than The standard design requirements proved that the piston return function had been restored to normal.

[0080] Actual vehicle testing and disassembly further confirmed the improvement effect; the gurgling noise and vibration at low speeds completely disappeared. Meanwhile, inspection of the brake pad surface showed uniform contact marks, and the wedge-shaped wear previously caused by the lazy piston was eliminated, strongly validating the effectiveness of targeted structural improvements based on signal decoupling diagnostics.

[0081] In summary, Example 2 (hot state) covers extreme operating conditions (high temperature, thermal deformation, hydraulic coupling) and is suitable for high-performance scenarios; Example 3 (cold state / chemical state) covers environment / materials (high humidity, rust, friction film) and is suitable for new energy / long-term storage scenarios; Example 4 (mechanical / tolerance) covers manufacturing / structure (machining accuracy, multi-piston consistency) and is suitable for production quality control (QC) and precision design of parts. As shown in Table 1, comparing the three examples, the core of this invention lies in separating the complex jitter signal into geometric components (AC), friction components, and resistance components (DC) through signal decoupling, thereby accurately locating the fault source.

[0082] Table 1 Comparative Analysis of the Three Examples

[0083] As shown in Table 1, Example 2 verifies the diagnostic capability of the method for external geometric excitations (disc / hub). Example 3 verifies the sensitivity of the method to interfacial friction characteristics (plate / disc contact surface). Example 4 verifies the method's ability to provide in-depth diagnosis and improvement guidance for minute tolerances in internal mechanical structures (caliper body / seals), and solves the hidden lazy piston problem by introducing a DLC coating and correcting tolerances.

[0084] Table 2 summarizes the differences between the present invention and the prior art.

[0085] Table 2. Differences between the present invention and the prior art

[0086] As shown in Table 2, compared to traditional measurement methods that only focus on time-domain averages and have ambiguous physical meanings, the decoupled measurement method proposed in this invention achieves a comprehensive breakthrough from the data dimension to the application depth. By introducing joint time-frequency domain analysis ( ) and sensitivity factors ( This method successfully separates the mixed resistance torque into two independent components: friction pair viscosity and geometric interference. This improves fault diagnosis from fuzzy energy consumption assessment to precise physical location (effectively distinguishing between abnormal seal return and structural thermal deformation incompatibility). It also successfully expands its application scope to the evaluation of NVH characteristics such as low-frequency jitter and roughness.

[0087] Example 5: This embodiment provides a decoupled measurement system for the drag and jitter characteristics of a fixed brake caliper, including: The data acquisition module is configured to acquire the time-domain drag torque signal of the fixed brake caliper. The DC component decoupling module is configured to: extract the DC component of the torque signal by integration based on the time-domain drag torque signal to characterize the return characteristics of the sealing ring; The AC component decoupling module is configured to: extract the AC component of the torque signal from the time-domain drag torque signal through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc; determine the drag fluctuation amplitude based on the AC component; construct a three-dimensional thermal-vibration-drag characteristic map based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; identify the danger zone that causes the drag fluctuation amplitude to exceed the threshold using the thermal-vibration-drag three-dimensional characteristic map; and determine the coupling sensitivity factor based on the ratio of the drag fluctuation amplitude to the thickness difference change amplitude within one rotation of the brake disc. The measurement and judgment module is configured to: determine whether there is a problem with the hydraulic seal return based on the DC component; and determine the accuracy risk and failure mode of the brake disc based on the drag fluctuation amplitude and coupling sensitivity factor.

[0088] The working method of the system is the same as the decoupled measurement method of the drag and vibration characteristics of the fixed brake caliper in Embodiment 1, and will not be repeated here.

[0089] Example 6: This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper as described in Embodiment 1.

[0090] Example 7: This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements the steps of the decoupling measurement method for the drag jitter characteristics of the fixed brake caliper described in Embodiment 1.

[0091] Example 8: This embodiment provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the steps of the decoupling measurement method for the drag and jitter characteristics of the fixed brake caliper described in Embodiment 1.

[0092] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A decoupled measurement method for the drag and vibration characteristics of a fixed brake caliper, characterized in that, include: Obtain the time-domain drag torque signal of the fixed brake caliper; Based on the time-domain drag torque signal, the DC component of the torque signal is extracted by integration to characterize the return characteristics of the sealing ring; Based on the time-domain drag torque signal, the AC component of the torque signal is extracted through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc. The drag fluctuation amplitude is determined based on the AC component; a three-dimensional thermal-vibration-drag characteristic map is constructed based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; the dangerous area that causes the drag fluctuation amplitude to exceed the threshold is marked by the thermal-vibration-drag three-dimensional characteristic map. The coupling sensitivity factor is determined based on the ratio of the drag fluctuation amplitude to the thickness difference change amplitude within one revolution of the brake disc. Determine whether there is a problem with the hydraulic seal return based on the DC component; The accuracy risk and failure mode of the brake disc are determined based on the drag fluctuation amplitude and coupling sensitivity factor.

2. The decoupled measurement method for the drag and vibration characteristics of a fixed brake caliper as described in claim 1, characterized in that, The time-domain drag torque signal is converted into an angular domain signal, and the angular domain signal is separated into DC and AC components through a mathematical model.

3. The decoupled measurement method for the drag and vibration characteristics of a fixed brake caliper as described in claim 1, characterized in that, The DC component is obtained by integrating and averaging the angular domain signal over one rotation cycle, which characterizes the piston seal's return capability. If the DC component exceeds a set threshold, it is determined to be a hydraulic seal return failure, regardless of the brake disc's accuracy. The DC component represents the constant drag torque component caused by the seal. : ； in, This is the constant dragging torque component caused by the sealing ring; This is the instantaneous drag torque function in the angular domain. For integration variables; This refers to the rotation angle of the brake disc.

4. The decoupled measurement method for the drag and vibration characteristics of a fixed brake caliper as described in claim 1, characterized in that, The AC component characterizes the periodic interference caused by brake disc end face runout or thickness difference. The residual after subtracting the DC component from the original signal: ； in, This is the angular domain signal within one rotation cycle; This is the DC component.

5. The decoupled measurement method for the drag and vibration characteristics of a fixed brake caliper as described in claim 4, characterized in that, The drag fluctuation amplitude is the peak-to-peak value of the drag torque fluctuation within one revolution of the brake disc: 。 6. The decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper as described in claim 1, characterized in that, The coupling sensitivity factor for: ； in, This is the coupling sensitivity factor; This is to reduce the amplitude of fluctuations; This represents the measured thickness difference variation amplitude within one revolution of the brake disc. Current test temperature The compression modulus correction factor for the lower friction plate.

7. The decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper as described in claim 1, characterized in that, The construction of the thermal-vibration-drag three-dimensional characteristic map includes: constructing a three-dimensional characteristic surface with the brake disc temperature as the X-axis, the brake disc end face runout as the Y-axis, and the drag fluctuation amplitude as the Z-axis.

8. The decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper as described in claim 1, characterized in that, If the AC component amplitude is greater than the threshold, the brake caliper is determined to have a risk of vibration under the current operating conditions; if the AC component amplitude is greater than or equal to the preset amplitude value and the coupling sensitivity factor is greater than or equal to the preset sensitivity value, the caliper structure stiffness design is deemed unreasonable and it is too sensitive to disc deformation. If the AC component amplitude is greater than or equal to the preset amplitude value but the coupling sensitivity factor is less than the preset sensitivity value, it is determined to be a problem with the brake disc manufacturing quality, and the caliper itself is qualified; if the AC component amplitude is less than the preset amplitude value but the coupling sensitivity factor is greater than or equal to the preset sensitivity value, it is determined to be an aging seal or lubrication failure.

9. A decoupled measurement system for the drag and jitter characteristics of a fixed brake caliper, characterized in that, include: The data acquisition module is configured to acquire the time-domain drag torque signal of the fixed brake caliper. The DC component decoupling module is configured to: extract the DC component of the torque signal by integration based on the time-domain drag torque signal to characterize the return characteristics of the sealing ring; The AC component decoupling module is configured to: extract the AC component of the torque signal from the time-domain drag torque signal through residual analysis to characterize the dynamic response of the brake caliper to the geometric runout of the brake disc; determine the drag fluctuation amplitude based on the AC component; construct a three-dimensional thermal-vibration-drag characteristic map based on the drag fluctuation amplitude, brake disc temperature, and brake disc end face runout; and identify the dangerous areas that cause the drag fluctuation amplitude to exceed the threshold using the three-dimensional thermal-vibration-drag characteristic map. The coupling sensitivity factor is determined based on the ratio of the drag fluctuation amplitude to the thickness difference change amplitude within one revolution of the brake disc. The measurement and judgment module is configured to determine whether a hydraulic seal return failure occurs based on the DC component. The accuracy risk and failure mode of the brake disc are determined based on the drag fluctuation amplitude and coupling sensitivity factor.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of the decoupled measurement method for the drag and jitter characteristics of a fixed brake caliper as described in any one of claims 1-8.

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