A machine and method for detecting clearance of automotive wheel hub units

Abstract

This invention discloses a clearance testing machine and method for automotive wheel hub units, belonging to the field of precision testing and automated control technology for automotive parts. The method includes: setting up a probe assembly comprising a primary main drive and a secondary vibration unit, and a multi-point hydraulic adaptive floating support platform below it; placing the automotive wheel hub unit on the platform, utilizing Pascal's principle to connect the hydraulic column, and automatically finding equipotential surfaces through fluid flow to eliminate tilting errors caused by microscopic unevenness; driving the probe to feed and generate axial shear vibration, utilizing thixotropy to destroy the grease network structure and liquefy it, thereby eliminating the virtual stiffness of the oil film; real-time monitoring and feedback, maintaining a static micro-load, and when the system determines a sudden change in stiffness from viscosity to elasticity, locking the position reading and calculating the axial clearance. This invention effectively avoids measurement data distortion caused by workpiece machining tolerances or clamping tilt, significantly improving the physical reference accuracy of clearance testing.

Description

Technical Field

[0001] This invention relates to the field of precision inspection and automated control of automotive parts, specifically to a machine and method for detecting clearance in automotive wheel hub units. Background Technology

[0002] With the rapid development of automotive precision manufacturing processes, the assembly quality of the wheel hub unit, as a key load-bearing component, directly affects the safety and comfort of the entire vehicle. This pursuit of high-precision assembly has significantly increased the requirements for the detection of internal clearances in the wheel hub unit.

[0003] Currently, existing testing technologies typically employ high-pressure loading to attempt to eliminate the influence of the oil film formed by internal grease in order to obtain the metal-to-metal contact interface. However, this method faces an irreconcilable contradiction: if the loading force is insufficient, it is difficult to penetrate the thixotropic grease network structure, leading to virtual stiffness interference with the measurement readings; if the loading force is blindly increased, the low stiffness of the hub unit flange makes it prone to elastic deformation, thus miscounting the structural deformation in the clearance value; in addition, installation tilt caused by workpiece machining errors or microscopic unevenness of the reference surface is difficult to eliminate automatically under traditional rigid support, easily introducing measurement axis deviation and Abbe error, further reducing the reliability of the test data.

[0004] Therefore, how to effectively eliminate oil film interference without compromising the geometric accuracy of the workpiece, and how to achieve adaptive alignment of the installation datum to ensure measurement authenticity, has become an urgent problem to be solved in this field.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure and therefore does not constitute information about prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a machine and method for detecting clearance in automotive wheel hub units, in order to solve the problems mentioned in the background art. The technical solution of this invention includes:

[0007] S1. Set up a loading probe assembly and an adaptive floating support platform, wherein the loading probe assembly includes a primary main drive unit and a secondary vibration unit integrated at the output end of the primary main drive unit, and the adaptive floating support platform is located directly below the loading probe assembly, and the adaptive floating support platform includes multiple hydraulic support columns distributed at multiple points.

[0008] S2. Place the car wheel hub unit on the adaptive floating support platform and connect the hydraulic support column using Pascal's principle. When there is a microscopic unevenness in the reference surface of the car wheel hub unit, the fluid in the hydraulic support column with greater force flows to the hydraulic support column with less force, driving the hydraulic support column to automatically find the mechanical equipotential surface to eliminate tilt error.

[0009] S3. Control the primary main drive unit to drive the secondary vibration unit to feed towards the automobile wheel hub unit, and at the same time start the secondary vibration unit to generate an axial shear vibration field. Utilize the thixotropic principle to destroy the mesh structure of the lubricating grease inside the automobile wheel hub unit, causing it to liquefy and eliminating the virtual stiffness generated by the oil film.

[0010] S4. Monitor the feedback signal of the secondary vibration unit in real time, and use the primary main drive unit to maintain a preset static micro-load to keep the measurement loop closed. When it is determined that the feedback signal represents a sudden change in stiffness from viscosity-dominated to elastic-dominated, lock the current position reading and calculate the axial clearance in combination with the drawing requirements.

[0011] Optionally, in step S1, the base of the adaptive floating support platform is provided with a common oil cavity, and the multiple hydraulic support columns are all interconnected with the common oil cavity. The number of hydraulic support columns is three, forming a three-point adaptive floating support structure.

[0012] Optionally, in step S3, the primary main drive unit uses a voice coil motor or an air-bearing cylinder to provide a static field to maintain contact; the secondary vibration unit uses a piezoelectric ceramic vibration unit to provide a high-frequency, low-amplitude physical intervention field.

[0013] Optionally, the vibration frequency range generated by the secondary vibration unit is 200Hz to 1kHz, and the vibration amplitude is less than 5μm, and the static micro-load applied by the primary main drive unit is 10N to 20N.

[0014] Optionally, the steps of S4 include:

[0015] Establish a real-time calculation model, set the excitation signal, and monitor the displacement response;

[0016] Monitor the complex impedance or phase lag of the driving current of the secondary vibration unit;

[0017] When a step change in the phase hysteresis is detected, or the amplitude decays to the trigger pre-screening threshold under constant driving force, it is determined that the steel ball has penetrated the oil film and contacted the metal raceway, confirming it as a true contact zero point. The pre-screening threshold is set to 3 to 5 times the root mean square value of the background noise of the impedance change rate signal collected by the system under no-load conditions.

[0018] Optionally, steps S3 to S4 employ a segmented closed-loop control strategy:

[0019] Phase 1: Activate the maximum vibration amplitude to control the primary main drive unit to feed rapidly;

[0020] In the second stage, when a slight change in impedance is detected, the feed speed of the first-stage main drive unit is reduced, and the vibration amplitude of the second-stage vibration unit is lowered.

[0021] Phase 3: When a sudden change in stiffness is detected, a latching action is immediately executed.

[0022] Optionally, in step S2, the adaptive floating support platform relies entirely on hydrostatic balance to ensure that the inner ring motion axis of the car wheel hub unit is parallel to the measurement axis without sensor feedback, so that the reaction force on the car wheel hub unit is purely axially distributed.

[0023] A clearance testing machine for automotive wheel hub units, comprising:

[0024] frame;

[0025] A probe assembly is loaded and mounted on the frame to provide axial movement and vibration excitation;

[0026] An adaptive floating support platform is mounted on the frame and located directly below the loading probe assembly to support the automotive wheel hub unit;

[0027] And the central control system;

[0028] The loading probe assembly includes a primary main drive unit that provides a static holding field and a secondary vibration unit that provides a high-frequency shear field;

[0029] The adaptive floating support platform includes multiple hydraulic support columns connected by a common oil cavity;

[0030] The central control system is electrically connected to both the primary main drive unit and the secondary vibration unit.

[0031] Optionally, the central control system is equipped with a phase-locking algorithm based on dynamic stiffness mutation, which is used to determine the metal contact state based on the complex impedance change fed back by the secondary vibration unit.

[0032] This invention provides a machine and method for detecting clearance in automotive wheel hub units, which has the following improvements and advantages compared with the prior art:

[0033] 1. This invention achieves automatic compensation for microscopic unevenness of the reference surface of the automotive wheel hub unit by setting up an adaptive floating bearing platform based on Pascal's principle and utilizing multi-point distributed and connected hydraulic support columns. When the wheel hub is placed, the force difference drives the fluid to flow in the common oil cavity, automatically finding the mechanical equipotential surface to eliminate tilting error. This pure hydrostatic balance mechanism can ensure that the height of the inner ring movement axis of the measured part is parallel to the measurement axis without the need for complex active leveling sensor feedback, ensuring that the reaction force is distributed in a pure axial direction. This effectively avoids the distortion of measurement data caused by workpiece machining tolerances or clamping tilt, and significantly improves the physical reference accuracy of clearance detection.

[0034] 2. This invention introduces a composite loading probe assembly comprising a primary main drive unit and a secondary vibration unit. Utilizing the axial shear vibration field generated by the secondary vibration unit, it cleverly applies the thixotropic principle to process the lubricating grease inside the wheel hub. High-frequency micro-amplitude vibration effectively disrupts the internal network structure of the lubricating grease, causing it to liquefy instantaneously and rapidly eliminating the virtual stiffness and viscous damping interference generated by the oil film. This design solves the problem of floating zero point caused by differences in oil film thickness and viscosity under traditional static loading methods, ensuring that the measuring probe can penetrate the oil film and directly contact the metal raceway, thereby obtaining the true mechanical clearance value and greatly improving the reproducibility of the test results.

[0035] 3. This invention establishes a phase-locking discrimination mechanism based on dynamic stiffness mutation. It determines the contact state by real-time monitoring of the complex impedance or driving current phase lag of the secondary vibration unit. Unlike the traditional single force threshold judgment, this system can sensitively capture the instantaneous step signal of the system transitioning from grease viscosity dominance to metal contact elasticity dominance. When a phase lag mutation or amplitude decay to near zero is detected, it is immediately determined as a true contact zero point and the reading is locked. This discrimination algorithm based on physical characteristics overcomes the masking of minute contact signals by environmental noise and friction, and achieves contact point identification with micron-level accuracy.

[0036] 4. This invention adopts a dynamic-static separation drive architecture and a segmented closed-loop control strategy. A stable static micro-load is provided by a primary main drive unit to maintain the contact loop closure, while piezoelectric ceramics are used to independently provide high-frequency physical intervention. This decoupling design not only ensures the constant static field required for measurement, but also independently realizes high-precision dynamic excitation. Combined with the segmented control logic of rapid feed-impedance micro-change deceleration-stiffness mutation latching, it not only ensures high-precision measurement, but also improves the efficiency of the detection cycle and effectively prevents feed overshoot from damaging the precision wheel hub raceway. Attached Figure Description

[0037] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0038] Figure 1 This is a schematic diagram of the external structure of this device;

[0039] Figure 2 This is a schematic diagram of the adaptive floating support platform of this device;

[0040] Figure 3 This is a schematic diagram of the structure of the probe loading assembly of this device;

[0041] Figure 4 This is a schematic diagram of the process flow of the method of the present invention.

[0042] In the diagram: 100, Loading probe assembly; 110, Primary main drive unit; 120, Secondary vibration unit; 200, Adaptive floating bearing platform; 210, Hydraulic support column; 220, Common oil chamber; 300, Automobile wheel hub unit; 400, Central control system. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0044] Example 1:

[0045] Please see Figure 1-4 A method for detecting clearance in automotive wheel hub units, comprising:

[0046] S1. Set up a loading probe assembly 100 and an adaptive floating support platform 200. The loading probe assembly 100 includes a primary main drive unit 110 and a secondary vibration unit 120 integrated into the output end of the primary main drive unit 110. The adaptive floating support platform 200 is located directly below the loading probe assembly 100. The adaptive floating support platform 200 includes multiple hydraulic support columns 210 distributed in multiple points.

[0047] S2. Place the car wheel hub unit 300 on the adaptive floating support platform 200, and use Pascal's principle to connect the hydraulic support column 210. When there is micro-unevenness in the reference surface of the car wheel hub unit 300, the fluid in the hydraulic support column 210 with large force flows to the hydraulic support column 210 with small force, driving the hydraulic support column 210 to automatically find the mechanical equipotential surface to eliminate tilt error.

[0048] S3. Control the primary main drive unit 110 to drive the secondary vibration unit 120 to feed towards the automobile wheel hub unit 300. At the same time, start the secondary vibration unit 120 to generate an axial shear vibration field. Use the thixotropic principle to destroy the mesh structure of the lubricating grease inside the automobile wheel hub unit 300 and liquefy it, eliminating the virtual stiffness generated by the oil film.

[0049] S4. Monitor the feedback signal of the secondary vibration unit 120 in real time, and use the primary main drive unit 110 to maintain the preset static micro-load to keep the measurement loop closed. When it is determined that the feedback signal represents a sudden change in stiffness from viscosity-dominated to elastic-dominated, lock the current position reading and calculate the axial clearance in combination with the design specifications.

[0050] In this embodiment, the contradiction between the low stiffness and easy deformation of the metal flange and the difficulty in breaking the internal grease film in the clearance detection of automobile wheel hub units in the prior art is solved by physical field coupling. The loading probe assembly 100 and the adaptive floating bearing platform 200 are positioned opposite each other to solve the oil film interference during the top loading process and the problem of datum plane alignment at the bottom, respectively. When the loading probe assembly 100 is pressed down, the primary main drive unit 110 provides basic feeding action, which, together with the physical intervention of the secondary vibration unit 120, makes the detection process no longer simply rely on high pressure extrusion, but uses physical characteristics to change the properties of the medium.

[0051] The adaptive floating bearing platform 200 eliminates installation tilt caused by workpiece machining errors through the dynamic balance of internal fluids. Through this multi-physics field synergy, the system can penetrate grease and identify the real metal contact interface with extremely low contact force. The position feedback grating ruler in the loading probe assembly 100 is arranged along the central axis and coincides with the measurement axis of the automobile wheel hub unit 300, thereby obtaining an accurate axial clearance value without causing elastic deformation of the workpiece.

[0052] In step S1, the base of the adaptive floating support platform 200 is provided with a common oil cavity 220, and multiple hydraulic support columns 210 are interconnected with the common oil cavity 220. There are three hydraulic support columns 210, forming a three-point adaptive floating support structure.

[0053] In this embodiment, the core of the adaptive floating support platform 200 lies in the fluid connectivity design of the common oil chamber 220; the three hydraulic support columns 210 are arranged in a triangle to form a defined support plane; when the car wheel hub unit 300 is placed on the hydraulic support column 210, if there is a microscopic height difference or flatness error on the bottom surface of the car wheel hub unit 300, the hydraulic support column 210 at the higher point will instantly bear a large external load, causing the fluid pressure in the chamber to rise; based on the principles of hydrostatics and Pascal's principle, this local pressure difference drives the fluid to flow from the high-pressure area to the low-pressure area, that is, to the other hydraulic support columns 210 with smaller force, pushing the other hydraulic support columns 210 to float upward; the redistribution of fluid in the common oil chamber 220 makes the fluid pressure at the three support points quickly tend to be balanced, and the height of the hydraulic support column 210 is adaptively adjusted accordingly;

[0054] To prevent excessive turbulence of the fluid between the common oil chamber 220 and the hydraulic support column 210, which could cause workpiece swaying, a throttling damping structure, such as a micro-orifice throttling valve or a porous media plug, is provided in the connecting flow channel between the hydraulic support column 210 and the common oil chamber 220. This throttling damping structure utilizes the friction resistance effect when the fluid passes through the micro-orifice to filter out high-frequency pressure fluctuations, enabling the system to quickly attenuate oscillation energy and enter a steady-state support mode after rapid alignment.

[0055] This process does not require an external power source. Instead, it utilizes the workpiece's own gravity and loading force to trigger fluid balance, allowing the automotive wheel hub unit 300 to automatically align under stress, eliminating bending moments caused by uneven bottom surfaces, and ensuring the parallelism between the measurement axis and the workpiece axis during the testing process.

[0056] In step S3, the primary main drive unit 110 uses a voice coil motor or an air-bearing cylinder to provide a static field to maintain contact; the secondary vibration unit 120 uses a piezoelectric ceramic vibration unit to provide a high-frequency, low-amplitude physical intervention field.

[0057] In this embodiment, the primary main drive unit 110 is selected from voice coil motors or low-friction air-float cylinders. These actuators have extremely low frictional hysteresis and precise force control characteristics. The main function of the primary main drive unit 110 is to deliver the loading probe assembly 100 to contact the workpiece and maintain a constant and small static load. This load is mainly used to eliminate mechanical backlash and maintain the closure of the measurement circuit, but is not enough to cause deformation of the metal parts.

[0058] The secondary vibration unit 120, integrated at the output of the primary main drive unit 110, employs a piezoelectric ceramic actuator. These devices possess extremely high response frequencies and nanometer-level displacement resolution. The secondary vibration unit 120 superimposes a high-frequency axial reciprocating motion onto a static load. To achieve closed-loop monitoring of this high-frequency physical intervention field, the secondary vibration unit 120 integrates a high-frequency strain gauge sensor, or the central control system 400 is equipped with a high-bandwidth voltage-current sampling circuit. This sampling circuit is used to acquire in real time the driving voltage waveform of the piezoelectric ceramic under the inverse piezoelectric effect and the current response waveform generated by the load reaction force, providing the original physical signal for subsequent impedance analysis without the need to deploy additional, difficult-to-install large displacement sensors.

[0059] This high-frequency, low-amplitude physical intervention field acts directly on the grease between the steel ball and the raceway. By utilizing the physical phenomenon of shear thinning, it reduces the viscosity of the grease, allowing the steel ball to penetrate the oil film smoothly, thus creating conditions for subsequent precise contact testing.

[0060] The vibration frequency range generated by the secondary vibration unit 120 is 200Hz to 1kHz, and the vibration amplitude is less than 5μm. The static micro-load applied by the primary main drive unit 110 is 10N to 20N.

[0061] In this embodiment, considering the thixotropic properties of automotive grease, the vibration frequency of the secondary vibration unit 120 is set between 200Hz and 1kHz. Within this frequency range, the soap-based fiber structure inside the grease will break down, exhibiting fluid properties. Here, fluid properties refer to the shear thinning phenomenon where the viscosity of a non-Newtonian fluid decreases sharply as the shear rate increases. That is, the grease temporarily changes from a semi-solid paste to a low-viscosity liquid-like state, thereby losing its supporting force on the steel ball.

[0062] The vibration amplitude is controlled within 5μm. This tiny amplitude is sufficient to disrupt the oil film structure, while being far smaller than the peak-to-trough difference in surface roughness of the bearing raceway, thus preventing vibration from causing fretting wear or indentation on the precision raceway surface. The static micro-load of 10N to 20N applied by the primary main drive unit 110 is far below the mechanical threshold for micron-level elastic deformation of the flange. This parameter combination ensures the liquefaction failure of the grease while guaranteeing the geometric stability of the metal structure, eliminating the superimposed effects of deformation error and oil film thickness error.

[0063] The steps in S4 include:

[0064] Establish a real-time calculation model, set the excitation signal, and monitor the displacement response;

[0065] Monitor the phase lag of the complex impedance or driving current of the secondary vibration unit 120;

[0066] When a step change in phase lag is detected, or the amplitude decays to the trigger pre-screening threshold under constant driving force, it is determined that the steel ball has penetrated the oil film and contacted the metal raceway, confirming it as a true contact zero point. The pre-screening threshold is set to 3 to 5 times the root mean square value of the background noise of the impedance change rate signal acquired by the system under no-load conditions.

[0067] In this embodiment, the detection system does not determine contact by directly measuring the force value, but rather infers the contact state by monitoring the rate of change of dynamic physical quantities; the established real-time calculation model focuses on the system's response characteristics to excitation signals; the calculation logic is as follows: the system adopts impedance analysis logic based on the lock-in amplification principle; firstly, the controller applies a known frequency to the secondary vibration unit. and amplitude The sinusoidal excitation voltage signal is denoted as ;

[0068] Among them, frequency The selection of the frequency range should avoid the inherent frequency range of the loaded probe assembly 100, and is usually set to the first-order resonant frequency of the system. 0.5 to 0.8 times that is ;in, The system uses the natural frequency parameters pre-determined and stored in the control system by performing frequency sweep modal analysis on the loaded probe assembly 100 to ensure that the system is in the stiffness control region and that the phase response has linearity.

[0069] The response current signal in the loop is read in real time by the sampling circuit. The sampling frequency of the analog-to-digital conversion in the sampling circuit Set as excitation frequency At least 20 times, that is To ensure the accuracy of phase calculation; due to the difference between the viscous damping of the grease and the elastic stiffness of the contact interface, the response current will experience amplitude attenuation and phase lag relative to the excitation voltage, denoted as . ;

[0070] The processor uses an orthogonal demodulation algorithm to process the acquired data. The phase lag angle is calculated by multiplying the signal with the reference signal and performing a low-pass filter. and equivalent impedance modulus The cutoff frequency of the low-pass filter Set as excitation frequency 1 / 5 to 1 / 2, to effectively filter out carrier frequencies At the same time, ensure that the bandwidth of the filter is sufficient to cover the envelope step change generated at the moment of contact, and avoid judgment lag caused by excessive smoothing;

[0071] The computational logic follows an interactive form that adheres to Ohm's law:

[0072]

[0073] in, For the excitation voltage amplitude, This is the measured current amplitude;

[0074] When the steel ball is suspended in a grease-coated state, the system load is mainly due to fluid viscous damping, and the phase lag angle is [not specified]. In the first stable state, corresponding to viscosity dominance; the moment the steel ball contacts the metal raceway, a phase lag angle occurs. A significant amplitude jump or polarity reversal occurs, along with an increase in impedance modulus. Rapidly rising; the system detected this or rate of change A point is identified as a contact point when the time exceeds a preset threshold; this preset threshold... The system is configured to continuously acquire impedance change rate signals for at least 10 signal cycles under no-load conditions. Root mean square value of background noise 3 to 5 times, that is To ensure effective differentiation between real contact mutation signals and environmental interference noise;

[0075] When the steel ball is suspended in a grease-coated state, the secondary vibration unit 120 faces a load dominated by viscous damping. At this time, the phase difference between the driving voltage and the displacement response is large, and the complex impedance is low. As the steel ball penetrates the oil film and contacts the metal raceway, the load characteristics instantly change from viscous fluid to rigid metal, causing the equivalent stiffness of the system to tend to infinity. This sudden change in physical properties is directly reflected in the electrical characteristics, manifested as a step-like change in the phase lag of the driving current, or a sudden decay of the vibration amplitude under constant driving force. The moment the system captures this characteristic signal, it determines that the steel ball has completely settled on the raceway surface. The position data recorded at this time is the true zero-point position, and there is no need to perform oil film thickness compensation calculation based on estimation.

[0076] It is worth noting that, since the adaptive floating support platform 200 will experience vertical displacement during the alignment process, the system monitors the change in floating height in real time using high-precision displacement sensors installed on the side of the adaptive floating support platform 200. To eliminate the influence of the secondary vibration unit 120 still being in a vibration state at the moment of determination on the position accuracy, the system locks the grating ruler reading of the current primary main drive unit 110. Afterwards, minor compensation and baseline correction calculations will be performed; the final axial clearance value... The calculation logic is as follows:

[0077]

[0078] in, This is the theoretical reference height value for zero clearance, set according to the product technical specifications and calibrated using a standard sample. The instantaneous reading at the moment when the stiffness change is triggered; This is the compensation amount for half the vibration amplitude; This is the floating height deviation of the adaptive floating platform relative to its initial calibration zero position; since the contact is determined to occur at the hard boundary of the vibration, i.e., the trough position, this compensation amount... The measurement corresponds to half of the vibration amplitude, ensuring that the measured value corresponds to the tight fit between the steel ball and the raceway.

[0079] Steps S3 to S4 employ a segmented closed-loop control strategy:

[0080] Phase 1: Activate the maximum vibration amplitude to control the rapid feed of the primary drive unit 110;

[0081] In the second stage, when a slight change in impedance is detected, the feed speed of the first-stage main drive unit 110 is reduced, and the vibration amplitude of the second-stage vibration unit 120 is lowered.

[0082] Phase 3: When a sudden change in stiffness is detected, a latching action is immediately executed.

[0083] In this embodiment, a segmentation strategy is adopted in order to balance detection efficiency and equipment security;

[0084] In the first stage, the primary drive unit 110 quickly approaches the workpiece, at which time the secondary vibration unit 120 outputs the maximum amplitude, using high energy to quickly disperse the thick grease and reduce fluid resistance.

[0085] In the second stage, when the system detects a slight change in impedance, it indicates that the probe has approached the metal interface. At this time, the primary main drive unit 110 reduces its speed and enters the search mode, while the secondary vibration unit 120 reduces its amplitude to prevent the steel ball from being damaged by a high-energy impact with the raceway.

[0086] In phase three, once the monitoring algorithm identifies the characteristic peak of stiffness change, indicating that metal contact has been achieved, the system immediately triggers the latching command of the grating ruler to record the current coordinate value. This strategy effectively protects the high-precision piezoelectric components and workpiece surface while ensuring cycle time.

[0087] In step S2, the adaptive floating support platform 200 relies entirely on hydrostatic balance to ensure that the inner ring motion axis of the car wheel hub unit 300 is parallel to the measurement axis without sensor feedback, so that the reaction force on the car wheel hub unit 300 is purely axially distributed.

[0088] In this embodiment, the design of the adaptive floating support platform 200 abandons the complex electronic level or displacement sensor feedback adjustment; it relies on the physical properties of fluids being incompressible and having equal pressure everywhere to achieve passive mechanical balance; no matter how irregular the bottom geometry of the car wheel hub unit 300 is, as long as it is placed on the hydraulic support column 210, each support point will automatically adjust its height until the force is uniform.

[0089] This purely mechanical hydraulic balancing method ensures that the axial force applied by the loading probe assembly 100 will not be decomposed into a radial component or generate a bending moment due to the tilt of the workpiece; therefore, the movement trajectory of the inner ring relative to the outer ring inside the car wheel hub unit 300 is strictly limited in the axial direction, ensuring that the detected displacement corresponds exactly to the axial clearance and eliminating the influence of Abbe error on measurement accuracy.

[0090] Example 2:

[0091] Please see Figure 1-3 A machine for testing clearance of automotive wheel hub units, comprising:

[0092] frame;

[0093] The probe assembly 100 is loaded and mounted on the frame to provide axial motion and vibration excitation;

[0094] An adaptive floating support platform 200 is mounted on the frame and located directly below the loading probe assembly 100 to support the automotive wheel hub unit 300.

[0095] And the central control system 400;

[0096] The loading probe assembly 100 includes a primary main drive unit 110 that provides a static holding field and a secondary vibration unit 120 that provides a high-frequency shear field;

[0097] The adaptive floating support platform 200 includes multiple hydraulic support columns 210 connected through a common oil cavity;

[0098] The central control system 400 is electrically connected to the primary main drive unit 110 and the secondary vibration unit 120 respectively, and is used to control the primary main drive unit 110 and the secondary vibration unit 120 to execute the automobile wheel hub unit clearance detection method in Embodiment 1.

[0099] In this embodiment, the frame serves as the basic support structure, ensuring the spatial relationship of each component. The loading probe assembly 100 is vertically mounted above the frame. The primary main drive unit 110, such as a linear module, works with a cylinder to handle large-stroke movement. The secondary vibration unit 120, such as a piezoelectric stack integrated at the probe end, handles micro-motion. The adaptive floating support platform 200 is mounted below, with its internal common oil chamber connected to multiple hydraulic support columns 210. The central control system 400, such as an industrial PC or a programmable logic controller (PLC), connects each driver and sensor via cables. The central control system 400 has built-in control logic to coordinate the feed action of the primary main drive unit 110 and the vibration output of the secondary vibration unit 120, and processes the electrical feedback signals from the piezoelectric unit, thereby achieving automated management of the entire detection process.

[0100] The central control system 400 is equipped with a phase-locking algorithm based on dynamic stiffness mutation, which is used to determine the metal contact state based on the complex impedance change fed back by the secondary vibration unit 120.

[0101] In this embodiment, the core function of the central control system 400 lies in data processing and discrimination. The algorithm running inside does not rely on simple threshold comparison, but performs dynamic trend analysis. The algorithm collects the voltage and current waveforms of the secondary vibration unit 120 in real time during the vibration process, calculates the phase difference between the two and the equivalent complex impedance. During the detection process, the algorithm continuously tracks the rate of change of these parameters. When the complex impedance value shows a sharp increase in slope, or the phase difference undergoes a sign reversal, the algorithm determines that this state corresponds to a physical solid-solid contact point. This algorithm logic transforms the fuzzy mechanical contact process into clear mathematical feature points, enabling the device to accurately capture micron-level clearance boundaries, thereby improving the repeatability and reproducibility of the detection results.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for detecting clearance in an automotive wheel hub unit, characterized in that, include: S1. Set up a loading probe assembly (100) and an adaptive floating support platform (200), wherein the loading probe assembly (100) includes a primary main drive unit (110) and a secondary vibration unit (120) integrated at the output end of the primary main drive unit (110), and the adaptive floating support platform (200) is located directly below the loading probe assembly (100), and the adaptive floating support platform (200) includes multiple hydraulic support columns (210) distributed in multiple points. S2. Place the car wheel hub unit (300) on the adaptive floating support platform (200) and connect the hydraulic support column (210) using Pascal's principle. When there is microscopic unevenness in the reference surface of the car wheel hub unit (300), the fluid in the hydraulic support column (210) with greater force flows to the hydraulic support column (210) with less force, driving the hydraulic support column (210) to automatically find the mechanical equipotential surface to eliminate tilt error. S3. Control the primary main drive unit (110) to drive the secondary vibration unit (120) to feed towards the automobile wheel hub unit (300), and at the same time start the secondary vibration unit (120) to generate an axial shear vibration field. Use the thixotropic principle to destroy the mesh structure of the lubricating grease inside the automobile wheel hub unit (300) to liquefy it and eliminate the virtual stiffness generated by the oil film. S4. Monitor the feedback signal of the secondary vibration unit (120) in real time, and use the primary main drive unit (110) to maintain the preset static micro-load to keep the measurement loop closed. When it is determined that the feedback signal represents a sudden change in stiffness from viscosity-dominated to elastic-dominated, lock the current position reading and calculate the axial clearance in combination with the drawing requirements.

2. The method for detecting clearance of an automotive wheel hub unit according to claim 1, characterized in that, In step S1, the base of the adaptive floating support platform (200) is provided with a common oil cavity (220), and the multiple hydraulic support columns (210) are all connected to the common oil cavity (220). The number of hydraulic support columns (210) is three, forming a three-point adaptive floating support structure.

3. The method for detecting clearance of an automotive wheel hub unit according to claim 1, characterized in that, In step S3, the primary main drive unit (110) uses a voice coil motor or an air flotation cylinder to provide a static field to maintain contact; the secondary vibration unit (120) uses a piezoelectric ceramic vibration unit to provide a high-frequency, low-amplitude physical intervention field.

4. The method for detecting clearance of an automotive wheel hub unit according to claim 3, characterized in that, The vibration frequency range generated by the secondary vibration unit (120) is 200Hz to 1kHz, and the vibration amplitude is less than 5μm. The static micro-load applied by the primary main drive unit (110) is 10N to 20N.

5. The method for detecting clearance of an automotive wheel hub unit according to claim 1, characterized in that, The steps in S4 include: Establish a real-time calculation model, set the excitation signal, and monitor the displacement response; Monitor the phase lag of the complex impedance or driving current of the secondary vibration unit (120); When a step change in the phase hysteresis is detected, or the amplitude decays to the trigger pre-screening threshold under constant driving force, it is determined that the steel ball has penetrated the oil film and contacted the metal raceway, confirming it as a true contact zero point. The pre-screening threshold is set to 3 to 5 times the root mean square value of the background noise of the impedance change rate signal collected by the system under no-load conditions.

6. The method for detecting clearance of an automotive wheel hub unit according to claim 1, characterized in that, Steps S3 to S4 employ a segmented closed-loop control strategy: Phase 1: Activate the maximum vibration amplitude to control the primary main drive unit (110) to feed rapidly; In the second stage, when a slight change in impedance is detected, the feed speed of the first-stage main drive unit (110) is reduced, and the vibration amplitude of the second-stage vibration unit (120) is lowered. Phase 3: When a sudden change in stiffness is detected, a latching action is immediately executed.

7. The method for detecting clearance of an automotive wheel hub unit according to claim 1, characterized in that, In step S2, the adaptive floating support platform (200) relies entirely on hydrostatic balance to ensure that the inner ring motion axis of the car wheel hub unit (300) is parallel to the measurement axis without sensor feedback, so that the reaction force on the car wheel hub unit (300) is purely axially distributed.

8. A machine for testing the clearance of automotive wheel hub units, characterized in that, include: frame; A probe assembly (100) is mounted on the frame to provide axial movement and vibration excitation; An adaptive floating support platform (200) is mounted on the frame and located directly below the loading probe assembly (100) to support the automotive wheel hub unit (300). And the central control system (400); The loading probe assembly (100) includes a primary main drive unit (110) that provides a static holding field and a secondary vibration unit (120) that provides a high-frequency shear field. The adaptive floating platform (200) includes multiple hydraulic support columns (210) connected through a common oil cavity. The central control system (400) is electrically connected to the primary main drive unit (110) and the secondary vibration unit (120) respectively, and is used by the primary main drive unit (110) and the secondary vibration unit (120) to perform the automobile wheel hub unit clearance detection method as described in any one of claims 1 to 7.

9. The automobile wheel hub unit clearance testing machine according to claim 8, characterized in that, The central control system (400) is equipped with a phase-locking algorithm based on dynamic stiffness mutation, which is used to determine the metal contact state based on the complex impedance change fed back by the secondary vibration unit (120).

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