A performance comprehensive evaluation test method for wheel hub motor assembly under extreme working condition

Abstract

A comprehensive performance evaluation test method for hub motor assemblies under extreme working conditions is disclosed. A test bench is constructed, comprising a base, a multi-degree-of-freedom vibration platform mounted on the base, an environmental simulation chamber located above the multi-degree-of-freedom vibration platform, and a load loading mechanism located within the environmental simulation chamber. The hub motor assembly under test is fixed at the center position of the multi-degree-of-freedom vibration platform, ensuring that the wheel axle centerline of the hub motor assembly coincides with the rotation center of the multi-degree-of-freedom vibration platform. The interior of the environmental simulation chamber is connected to an external medium source via a piping system. This invention, through the combined motion of the lower translation module and the middle rotation module of the multi-degree-of-freedom vibration platform, not only simulates the up-and-down bumps and left-and-right swaying of a vehicle traveling on rough roads, but also ensures that the hub motor assembly under test remains rigidly fixed and centered under severe vibration through the arc-shaped contact surface of the hydraulic locking claws on the upper clamping flange.

Description

Technical Field

[0001] This invention belongs to the field of hub motor testing technology, specifically a comprehensive performance evaluation test method for hub motor assemblies under extreme working conditions. Background Technology

[0002] With the rapid development of new energy vehicle technology, in-wheel motors, as a major component driving vehicles, have been widely used due to their compact structure, high transmission efficiency, and flexible control. However, in-wheel motors are directly integrated inside the wheel, operating in extremely harsh environments. They must withstand high-frequency mechanical vibrations and impacts from the road surface, as well as the corrosive effects of rain, snow, mud, and alternating high and low temperatures. Furthermore, they must bear enormous driving torque and braking loads at high speeds. Therefore, conducting a comprehensive performance evaluation of the in-wheel motor assembly under extreme conditions during the research and development phase is crucial, as it directly relates to the vehicle's driving safety and reliability.

[0003] Most existing in-wheel motor testing technologies suffer from the following technical problems: First, traditional test benches mostly use vibration tables with a single degree of freedom, which can only realize simple harmonic vibration in the vertical or horizontal direction. They cannot simulate the complex motion state of up-and-down bumping, left-and-right swaying and torsional vibration that occurs when a vehicle is driving on a rough road. Existing fixtures mostly use rigid bolt connections or simple planar clamping methods. Under severe high-frequency complex vibration, the motor under test is prone to slight relative slippage or loosening, resulting in loss of installation alignment accuracy, introducing additional eccentric loads and false vibration signals. This makes the test data unable to truly reflect the dynamic characteristics of the motor rotor, and may even cause the test to be interrupted due to unstable clamping.

[0004] Secondly, in terms of environmental adaptability testing, existing environmental chambers are usually single-function and have a slow temperature switching process, requiring several hours to complete the transition from extreme cold to high temperature. They cannot reproduce the millisecond-level drastic temperature changes that occur when a vehicle is driven from an icy or snowy road into a high-temperature environment or is exposed to the sun after being washed by heavy rain. The gradual temperature changes cannot effectively stimulate the concentration of thermal stress inside the insulating material, and it is also difficult to verify the dynamic sealing performance of the seals under rapid thermal expansion and contraction.

[0005] Furthermore, when the test bench undergoes multi-degree-of-freedom vibration, the fixed loading roller cannot follow the spatial trajectory of the tire, causing slippage, separation, or drastic changes in the contact angle between the roller and the tire tread. This results in huge fluctuations in the applied normal pressure and resistance torque, making it impossible to maintain a constant level. This not only leads to distorted load data and an inability to accurately assess the output characteristics of the motor under dynamic load, but also causes wear on the tire or damage to the loading equipment due to poor contact. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a comprehensive evaluation and testing method for the performance of hub motor assembly under extreme working conditions, so as to at least partially solve the above-mentioned technical problems.

[0007] The technical solution adopted in this invention is as follows: This invention proposes a comprehensive performance evaluation and testing method for hub motor assemblies under extreme operating conditions, comprising the following steps: Step 1: Construct a test bench, which includes a base, a multi-degree-of-freedom excitation platform set on the base, an environmental simulation chamber located above the multi-degree-of-freedom excitation platform, and a load loading mechanism set inside the environmental simulation chamber. Step 2: Fix the hub motor assembly under test at the center position of the multi-degree-of-freedom vibration platform, so that the wheel axle centerline of the hub motor assembly under test coincides with the rotation center of the multi-degree-of-freedom vibration platform; Step 3: Connect the interior of the environmental simulation chamber to the external medium source through a piping system, which includes a coolant circulation pipe, a spray pipe, and a gas replacement pipe; Step 4: The output end of the load loading mechanism contacts the tread of the tire of the wheel hub motor assembly under test to form a friction transmission pair; Step 5: Under the preset extreme working condition sequence, the multi-degree-of-freedom excitation platform is synchronously controlled to generate composite vibration signals, the environmental simulation chamber adjusts the temperature, humidity and medium concentration, the load loading mechanism applies dynamic resistance torque, and the electrical parameters, mechanical vibration parameters and thermal imaging data of the hub motor assembly under test are collected in real time.

[0008] In one embodiment of the present invention, the multi-degree-of-freedom vibration platform includes a lower translation module, a middle rotation module, and an upper clamping flange. The lower translation module is slidably connected to the top surface of the base via a first linear guide pair. The middle rotation module is mounted on the center of the top surface of the lower translation module via a slewing bearing. The upper clamping flange is slidably connected to the top surface of the middle rotation module in a radial direction via a second linear guide pair. The center of the upper clamping flange has a mounting through hole for the hub motor assembly to be tested. Four hydraulic locking claws are evenly distributed circumferentially on the inner wall of the mounting through hole, and each hydraulic locking claw has an arc-shaped contact surface at its end.

[0009] In one embodiment of the present invention, the environmental simulation chamber is a double-layered hollow structure, including an inner chamber and an outer chamber, with a heat-insulating cavity formed between the inner and outer chambers. A drainage channel is provided at the bottom of the inner chamber, and the lowest point of the drainage channel is connected to a waste liquid collection tank through a one-way valve. Twelve high-pressure atomizing nozzles are evenly arranged along the circumference on the inner side of the top of the inner chamber. The spray angle of each high-pressure atomizing nozzle is adjustable, and the inlet end of the high-pressure atomizing nozzle is connected to a high-temperature steam source and a low-temperature ice-water mixture source through a three-way valve.

[0010] In one embodiment of the present invention, the load loading mechanism includes a gantry support, a horizontal moving slide, a vertical lifting cylinder, and a roller loading assembly. The gantry support spans above the environmental simulation chamber. The horizontal moving slide reciprocates along the crossbeam of the gantry support via a gear and rack mechanism. The vertical lifting cylinder is fixed to the bottom of the horizontal moving slide. The roller loading assembly is suspended from the piston rod end of the vertical lifting cylinder via a force sensor. The roller loading assembly includes a loading roller, a built-in brake, and a high-inertia flywheel. The outer surface of the loading roller is covered with a replaceable friction coefficient adjustment layer.

[0011] In one embodiment of the present invention, a crushing stone impact simulation subsystem is further included. The crushing stone impact simulation subsystem includes a storage hopper, a screw feeder, an acceleration pipe, and an impact target area. The storage hopper is located at a high external position outside the environmental simulation chamber. The inlet end of the acceleration pipe is connected to the outlet of the screw feeder, and the outlet end of the acceleration pipe passes through the side wall of the environmental simulation chamber and points to the lower half of the hub motor assembly under test. Three electromagnetic acceleration coils are arranged axially at intervals inside the acceleration pipe. The impact target area is located directly below the hub motor assembly under test, and a grid-shaped rebound baffle is provided at the bottom of the impact target area.

[0012] In one embodiment of the present invention, a combined mud and water soaking and flushing module is further included. The combined mud and water soaking and flushing module includes a mud preparation tank, a submersible pump, and an annular spray pipe. The mud preparation tank is connected to a drainage trough at the bottom of the environmental simulation chamber through a feed pipe. The submersible pump is immersed in the mud liquid in the mud preparation tank. The outlet of the submersible pump is connected to the annular spray pipe through a flexible hose. The annular spray pipe is sleeved on the outside of the wheel hub motor assembly under test. A plurality of oblique nozzles are evenly distributed on the inner wall of the annular spray pipe facing the wheel hub motor assembly under test. The axis of the oblique nozzles forms a 45-degree angle with the radial direction of the wheel hub motor assembly under test.

[0013] In one embodiment of the present invention, the data acquisition system includes an embedded main control unit, a high-frequency current transformer, a three-phase voltage sampling module, a six-dimensional force sensor array, a fiber optic temperature sensor network, and a high-speed industrial camera. The high-frequency current transformer is sleeved on the three-phase input cable of the hub motor assembly under test. The six-dimensional force sensor array is embedded between the upper clamping flange and the mounting interface of the hub motor assembly under test. The fiber optic temperature sensor network is attached to the stator winding end and the bearing outer ring surface of the hub motor assembly under test. The high-speed industrial camera is aimed at the air gap position of the hub motor assembly under test through a transparent observation window.

[0014] In one embodiment of the present invention, the execution logic of the extreme working condition sequence is as follows: First, the multi-degree-of-freedom excitation platform is started, causing the lower translation module to perform a sinusoidal reciprocating motion of ±50mm at a frequency of 0.5Hz, while the middle rotation module swings at a frequency of 1Hz and ±30 degrees; then, the environmental simulation chamber is turned on, and an ice-water mixture at a temperature of -40℃ is sprayed through a high-pressure atomizing nozzle for 10 minutes, followed by switching to high-temperature steam at 85℃ for 20 minutes; during this period, the gravel impact simulation subsystem is started simultaneously, and the electromagnetic acceleration coil is controlled to launch ceramic projectiles with a diameter of 10mm at a frequency of 5 shots per second; finally, the roller loading component of the load loading mechanism is controlled to apply a resistance torque from 0 to 90% of the peak torque in a step manner, and a pulsating torque with a frequency of 20Hz and an amplitude of 10% of the peak torque is superimposed during the peak holding phase.

[0015] In one embodiment of the present invention, an online sealing performance monitoring unit is further included. The online sealing performance monitoring unit includes a tracer gas generator, a mass spectrometer leak detector, and a negative pressure suction hood. The tracer gas generator is connected to the air inlet of the environmental simulation chamber and is used to fill the environmental simulation chamber with a mixture of helium and air. The negative pressure suction hood is fastened to the outside of the bearing sealing cover of the hub motor assembly under test. The negative pressure suction hood is connected to the air intake of the mass spectrometer leak detector through a sampling tube. When the helium concentration in the environmental simulation chamber reaches a preset threshold, the negative pressure suction hood is activated and gas is drawn into the mass spectrometer leak detector at a constant flow rate for analysis.

[0016] In one embodiment of the present invention, a real-time correction module based on digital twin is further included. The real-time correction module includes a local server, a 3D modeling engine, and a feedback controller. The local server communicates with the data acquisition system via gigabit Ethernet to receive real-time acquired electrical parameters, mechanical vibration parameters, and thermal imaging data. The 3D modeling engine runs a finite element model of the hub motor assembly under test on the local server and maps the real-time data to the corresponding nodes of the finite element model to calculate the stress concentration factor and the predicted temperature rise. When the stress concentration factor exceeds the safety threshold or the predicted temperature rise exceeds the insulation class limit, the feedback controller sends a load reduction command to the multi-degree-of-freedom excitation platform, environmental simulation chamber, or load loading mechanism to adjust the vibration amplitude, ambient temperature, or resistance torque.

[0017] The beneficial effects of the technical solution of this invention are as follows: This invention uses a multi-degree-of-freedom vibration platform to simulate the up-and-down bumps and left-and-right swaying of a vehicle traveling on rough roads through the combined motion of the lower translation module and the middle rotation module. Furthermore, the arc-shaped contact surface of the hydraulic locking claw on the upper clamping flange ensures that the hub motor assembly under test remains rigidly fixed and aligned even under severe vibration, avoiding additional errors caused by loose installation. This ensures that the inertial load applied to the motor fully conforms to the principles of dynamics.

[0018] The environmental simulation chamber of this invention adopts a double-layer hollow structure to effectively isolate the interference of extreme internal temperatures on external equipment. The twelve high-pressure atomizing nozzles evenly distributed on the top can complete the switching from a -40°C ice-water mixture to 85°C high-temperature steam in milliseconds. The intense thermal shock test greatly accelerates the aging process of the motor insulation material and verifies the reliability of the seals under thermal expansion and contraction. Combined with the one-way valve drainage system at the bottom, it ensures the controllability of the medium concentration inside the chamber and the purity of the test environment.

[0019] The load loading mechanism of this invention utilizes the straddle layout of the gantry bracket and the gear and rack drive of the horizontal moving slide to achieve flexible spatial tracking of the loading roller, ensuring that the loading roller always maintains the optimal contact angle with the tire tread regardless of the movement of the vibration platform. The real-time feedback of the force sensor, combined with the adjustment of the vertical lifting cylinder, ensures that the applied positive pressure remains constant. The replaceable friction coefficient adjustment layer further expands the coverage of the test scenario, enabling the simulation of different adhesion conditions from icy and snowy roads to dry asphalt roads.

[0020] The gravel impact simulation subsystem of this invention accelerates ceramic projectiles in multiple stages using electromagnetic acceleration coils, giving the particles extremely high kinetic energy. This makes the impact effect far exceed that of traditional gravity drop tests, and can realistically simulate the destructive force of stones on the motor housing during high-speed driving. Combined with the secondary impact effect formed by the grid-like rebound baffle below, it can assess the structural strength and coating adhesion of the motor housing.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of the method for comprehensive performance evaluation and testing of hub motor assembly under extreme working conditions proposed in this embodiment of the invention; Figure 2 This is the first test flowchart of the test method for comprehensive performance evaluation of hub motor assembly under extreme working conditions proposed in this embodiment of the invention. Figure 3 This is the second test flowchart of the comprehensive performance evaluation test method for hub motor assembly under extreme working conditions proposed in this embodiment of the invention; Figure 4 This is the third test flowchart of the comprehensive performance evaluation test method for hub motor assembly under extreme working conditions proposed in this embodiment of the invention; Figure 5This is the fourth test flowchart of the comprehensive performance evaluation test method for hub motor assembly under extreme working conditions proposed in this embodiment of the invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] The following describes a method for comprehensive performance evaluation and testing of a hub motor assembly under extreme operating conditions, with reference to the accompanying drawings.

[0025] like Figures 1 to 5 As shown in the figure, this invention provides a comprehensive performance evaluation test method for a hub motor assembly under extreme operating conditions, including the following steps: Step 1: Construct a test bench. The test bench includes a base, a multi-degree-of-freedom excitation platform set on the base, an environmental simulation chamber located above the multi-degree-of-freedom excitation platform, and a load loading mechanism set inside the environmental simulation chamber. Step 2: Fix the hub motor assembly under test at the center position of the multi-degree-of-freedom vibration platform, so that the wheel axle centerline of the hub motor assembly under test coincides with the rotation center of the multi-degree-of-freedom vibration platform; Step 3: Connect the interior of the environmental simulation chamber to the external medium source through a piping system, which includes coolant circulation pipes, spray pipes, and gas replacement pipes; Step 4: The output end of the load loading mechanism contacts the tread of the tire of the wheel hub motor assembly under test to form a friction transmission pair; Step 5: Under the preset extreme working condition sequence, the multi-degree-of-freedom excitation platform is synchronously controlled to generate composite vibration signals, the environmental simulation chamber adjusts the temperature, humidity and medium concentration, the load loading mechanism applies dynamic resistance torque, and the electrical parameters, mechanical vibration parameters and thermal imaging data of the hub motor assembly under test are collected in real time.

[0026] In a specific application of this invention, the multi-degree-of-freedom vibration platform is mounted on a base and serves as the power input source, starting to operate according to a preset program. The lower translation module drives the middle rotation module to perform reciprocating linear motion in the horizontal plane, thereby simulating the lateral displacement impact generated when a vehicle travels on a rough road surface. At the same time, the middle rotation module drives the upper clamping flange to swing at an angle, thereby replicating the tilting posture of the vehicle when cornering or crossing obstacles. The composite motion is directly transmitted to the wheel hub motor assembly under test, which is fixed at the center of the upper clamping flange, so that the wheel axle centerline of the wheel hub motor assembly under test changes its spatial position synchronously with the rotation center of the multi-degree-of-freedom vibration platform.

[0027] The environmental simulation chamber surrounds the multi-degree-of-freedom vibration platform and completely encloses the hub motor assembly under test within its closed space. The piping system then supplies coolant, spray water mist, or specific gases from an external medium source into the environmental simulation chamber. The coolant circulation pipe flows within the chamber walls to maintain a stable temperature for the chamber structure. The spray pipes spray liquids of different temperatures onto the surface of the hub motor assembly under test to simulate the thermal shock conditions of heavy rain or snow cover. The gas replacement pipes fill the environmental simulation chamber with high-humidity air or corrosive gases to accelerate the aging process of the hub motor assembly's seals. The load loading mechanism is activated inside the environmental simulation chamber and adjusts the position of its output end. The roller loading component of the load loading mechanism moves downward until the friction coefficient adjustment layer covering the outer surface is tightly pressed against the tire surface of the hub motor assembly under test. The contact point between the two forms a friction transmission pair and generates sufficient positive pressure to transmit torque.

[0028] When the hub motor assembly under test vibrates under the drive of the multi-degree-of-freedom excitation platform, the load loading mechanism automatically compensates for the positional deviation through the horizontal moving slide and the vertical lifting cylinder to maintain the contact stability of the friction transmission pair. The built-in brake inside the load loading mechanism starts to work and applies resistance to the large inertia flywheel. The large inertia flywheel converts the resistance torque into a dynamic load and transmits it to the tire of the hub motor assembly under test through the loading roller. The hub motor assembly under test must output a corresponding electromagnetic torque to overcome this dynamic resistance torque.

[0029] At this time, the preset extreme working condition sequence commands are synchronously issued to each execution unit. The frequency of the composite vibration signal output by the multi-degree-of-freedom excitation platform is aligned with the frequency of the dynamic resistance torque pulsation applied by the load loading mechanism on the time axis. The temperature and humidity change curves in the environmental simulation chamber are coupled with the mechanical load change curves. The wheel hub motor assembly under test continues to operate in this extreme environment of multi-field coupling of electricity, heat, force, and vibration. The high-frequency current transformer captures the current waveform distortion on the three-phase input cable of the wheel hub motor assembly under test in real time. The three-phase voltage sampling module synchronously records the fluctuation amplitude of the terminal voltage. The six-dimensional force sensor array senses the three-directional forces and three-directional torques received at the mounting interface of the wheel hub motor assembly under test from the multi-degree-of-freedom excitation platform.

[0030] The fiber optic temperature sensor network converts minute temperature changes at the stator winding end and bearing outer ring surface of the hub motor assembly under test into optical signals and transmits them to the data acquisition system. A high-speed industrial camera continuously captures deformation images of the air gap position of the hub motor assembly under test through the transparent observation window of the environmental simulation chamber. If the gravel impact simulation subsystem is activated, simulated gravel is released from the high-level storage hopper. The screw feeder controls the flow rate of the simulated gravel, and the electromagnetic acceleration coil in the acceleration pipe gives the simulated gravel extremely high initial velocity. The simulated gravel passes through the side wall of the environmental simulation chamber and impacts the lower half of the outer shell of the hub motor assembly under test, causing local pits or coating peeling. If the mud immersion and flushing combined module is activated, the submersible pump pumps high-concentration mud slurry from the mud preparation tank to the annular spray pipe. The angled nozzles on the annular spray pipe spray high-speed mud slurry at a 45-degree angle onto the surface of the hub motor assembly under test to simulate the wear effect under muddy road conditions.

[0031] The online sealing performance monitoring unit then fills the environmental simulation chamber with a helium-containing gas mixture. Under the action of the pressure difference, the tracer gas attempts to penetrate the sealing gap of the hub motor assembly under test. The negative pressure suction hood forms a local low-pressure zone outside the bearing seal cover of the hub motor assembly under test and sucks in the leaked helium-containing gas. The mass spectrometer leak detector analyzes the helium concentration in the sucked gas to quantify the degree of sealing failure. The real-time correction module based on digital twins receives real-time data uploaded by all sensors on the local server. The 3D modeling engine maps the real-time data to the corresponding nodes of the finite element model of the hub motor assembly under test and calculates the stress concentration factor and temperature rise prediction value in real time. Once the calculation result exceeds the safety threshold, the feedback controller immediately sends a command to the multi-degree-of-freedom excitation platform to reduce the vibration amplitude or a command to the load loading mechanism to reduce the resistance torque. The entire system ensures that the hub motor assembly under test can still complete the predetermined test process without catastrophic damage under working conditions close to the failure limit through this closed-loop control logic.

[0032] In one specific embodiment, the multi-degree-of-freedom vibration platform includes a lower translation module, a middle rotation module, and an upper clamping flange. The lower translation module is slidably connected to the top surface of the base via a first linear guide pair. The middle rotation module is mounted on the center of the top surface of the lower translation module via a slewing bearing. The upper clamping flange is slidably connected to the top surface of the middle rotation module via a second linear guide pair. The center of the upper clamping flange has a mounting through hole for the hub motor assembly to be tested. Four hydraulic locking claws are evenly distributed circumferentially on the inner wall of the mounting through hole, and each hydraulic locking claw has an arc-shaped contact surface at its end.

[0033] The environmental simulation chamber has a double-layered hollow structure, consisting of an inner chamber and an outer chamber. A heat-insulating cavity is formed between the inner and outer chambers. A drainage channel is provided at the bottom of the inner chamber, and the lowest point of the drainage channel is connected to a waste liquid collection tank through a one-way valve. Twelve high-pressure atomizing nozzles are evenly arranged along the circumference on the inner side of the top of the inner chamber. The spray angle of each high-pressure atomizing nozzle is adjustable, and the inlet end of the high-pressure atomizing nozzle is connected to a high-temperature steam source and a low-temperature ice-water mixture source through a three-way valve.

[0034] In a specific application of this invention, the lower translation module, as the bottom foundation of the entire kinematic chain, first receives displacement commands from the control system. The slider at the bottom of the lower translation module performs high-precision linear reciprocating motion along the first linear guide pair fixed to the top surface of the base. The linear motion directly transmits the horizontal acceleration and impact force to the middle rotating module installed at the center of its top surface. The middle rotating module obtains the degree of freedom to rotate around the vertical axis through the slewing bearing connected to the lower translation module at its bottom. The large-diameter balls inside the slewing bearing can simultaneously withstand the huge axial load from the upper structure and the overturning moment generated when the vehicle is cornering at its limit. Driven by the servo motor, the middle rotating module swings at an angle relative to the lower translation module to simulate the steering action of the vehicle or the body roll caused by uneven road surface. The upper clamping flange is radially slidably connected to the top surface of the middle rotating module through the second linear guide pair, so that the upper clamping flange can be radially fine-tuned according to the wheel track change or eccentric mass distribution of the hub motor assembly under test to eliminate the unbalanced centrifugal force during rotation.

[0035] When the hub motor assembly under test is placed in the mounting through hole in the center of the upper clamping flange, the four hydraulic locking claws retract synchronously towards the center under the action of the hydraulic system. The arc-shaped contact surface at the end of each hydraulic locking claw wraps around the outer circumferential surface of the hub motor assembly under test. The arc-shaped contact surface increases the contact area and uses the wedge self-locking principle to firmly fix the hub motor assembly under test to prevent it from loosening or falling off during severe vibration.

[0036] The environmental simulation chamber located above now encloses the entire motion mechanism. The double-layered hollow structure of the environmental simulation chamber begins to play a role in thermal insulation. The heat-insulating cavity formed between the inner and outer chambers effectively blocks the interference of external environmental temperature and reduces energy loss during extreme internal temperature tests. When the test needs to simulate rainstorm or extreme cold conditions, the control system opens the three-way valve to connect the low-temperature ice-water mixture source. Twelve high-pressure atomizing nozzles atomize the ice-water mixture into tiny droplets and spray them at an adjustable angle onto the vibrating hub motor assembly under test. The tiny droplets undergo a phase change and absorb heat instantly upon contact with the high-temperature motor housing, thereby generating severe thermal shock stress.

[0037] When the test requires simulating a high-temperature and high-humidity environment, the three-way valve switches to a high-temperature steam source. High-pressure atomizing nozzles spray high-temperature steam to quickly fill the inner chamber space, causing condensation on the surface of the tested hub motor assembly to accelerate the aging test of the insulation materials. A drainage trough at the bottom of the inner chamber collects waste liquid and condensate after spraying. The waste liquid, under gravity, converges at the lowest point of the drainage trough and flows through a one-way valve to a waste liquid collection tank. The one-way valve prevents odors or harmful gases from flowing back into the inner chamber, thus ensuring the purity of the test environment. Throughout the process, the mechanical... The motion and environmental simulation chamber maintains spatial and temporal synchronization in its thermal and humidity regulation. The linear vibration of the lower translation module and the oscillation of the middle rotation module are superimposed and transmitted to the wheel hub motor assembly under test through the upper clamping flange. The medium flow field sprayed from the high-pressure atomizing nozzle covers all exposed surfaces of the wheel hub motor assembly under test. The constant clamping force provided by the hydraulic locking claw ensures that the vibration energy is transmitted to the interior of the wheel hub motor assembly under test without loss. The heat insulation cavity maintains the uniformity of the internal chamber temperature to avoid local hot and cold spots affecting the accuracy of the test results. The rapid drainage capability of the drainage trough prevents water accumulation from causing short circuit risks to electrical components.

[0038] In one specific embodiment, the load loading mechanism includes a gantry support, a horizontal moving slide, a vertical lifting cylinder, and a roller loading assembly. The gantry support spans above the environmental simulation chamber. The horizontal moving slide reciprocates along the crossbeam of the gantry support via a gear and rack mechanism. The vertical lifting cylinder is fixed to the bottom of the horizontal moving slide. The roller loading assembly is suspended from the piston rod end of the vertical lifting cylinder via a force sensor. The roller loading assembly includes a loading roller, a built-in brake, and a high-inertia flywheel. The outer surface of the loading roller is covered with a replaceable friction coefficient adjustment layer.

[0039] It also includes a crushed stone impact simulation subsystem, which comprises a storage hopper, a screw feeder, an acceleration pipe, and an impact target area. The storage hopper is located high outside the environmental simulation chamber. The inlet end of the acceleration pipe connects to the outlet end of the screw feeder, and the outlet end of the acceleration pipe passes through the side wall of the environmental simulation chamber and points towards the lower half of the hub motor assembly under test. Three electromagnetic acceleration coils are axially spaced inside the acceleration pipe. The impact target area is located directly below the hub motor assembly under test, and the bottom of the impact target area is equipped with a grid-like rebound baffle. It also includes mud and water immersion... The combined immersion and flushing module includes a mud preparation tank, a submersible pump, and an annular spray pipe. The mud preparation tank is connected to a drainage trough at the bottom of the environmental simulation chamber via a feed pipe. The submersible pump is immersed in the mud liquid in the mud preparation tank. The outlet of the submersible pump is connected to the annular spray pipe via a flexible hose. The annular spray pipe is sleeved on the outside of the wheel hub motor assembly under test. Several oblique nozzles are evenly distributed on the inner wall of the annular spray pipe facing the wheel hub motor assembly under test. The axis of the oblique nozzles forms a 45-degree angle with the radial direction of the wheel hub motor assembly under test.

[0040] In a specific application of this invention, the horizontal moving slide, driven by a servo motor, reciprocates linearly along the crossbeam of the gantry bracket via a gear and rack mechanism to track the horizontal displacement of the wheel hub motor assembly under test under the action of the multi-degree-of-freedom excitation platform in real time. The vertical lifting cylinder is fixed at the bottom of the horizontal moving slide and changes its spatial position synchronously with the movement of the slide. The piston rod of the vertical lifting cylinder extends or retracts to precisely adjust the height of the roller loading assembly suspended at its end. The force sensor monitors the contact pressure between the roller loading assembly and the tire tread of the wheel hub motor assembly under test in real time and feeds the signal back to the control system to maintain a constant positive pressure.

[0041] The loading roller in the roller loading assembly is driven to rotate by the hub motor assembly under test under the action of friction. The replaceable friction coefficient adjustment layer on the outer surface of the loading roller is in close contact with the tire tread to simulate the adhesion coefficient under different road conditions. The shaft of the loading roller is connected to the internal high inertia flywheel. The high inertia flywheel uses rotational inertia to simulate the inertia of the vehicle mass when the vehicle is moving. The built-in brake applies a controllable electromagnetic resistance torque to the high inertia flywheel, thereby transmitting the resistance to the loading roller and finally acting on the hub motor assembly under test to simulate climbing or braking conditions.

[0042] Simultaneously, the gravel impact simulation subsystem starts working. Simulated gravel at a high position in the storage hopper falls into the screw feeder under the action of gravity. The screw feeder controls the falling flow of simulated gravel through rotating blades and feeds it evenly into the inlet of the acceleration pipe. The three electromagnetic acceleration coils inside the acceleration pipe are energized in sequence to generate a traveling wave magnetic field. The traveling wave magnetic field generates a continuous electromagnetic thrust on the ferromagnetic simulated gravel, causing it to accelerate rapidly in the pipe and obtain an extremely high exit velocity. The high-speed flying simulated gravel passes through the opening in the side wall of the environmental simulation chamber and directly impacts the lower half of the test hub motor assembly, which is vibrating and rotating, to reproduce the impact damage of gravel road surface to motor housing. After impact, the simulated gravel falls into the impact target area located directly below the test hub motor assembly. The grid-like rebound baffle at the bottom of the impact target area bounces some of the gravel back to form a secondary impact to simulate the complex effect of gravel splashing in real road conditions.

[0043] The mud immersion and flushing combined module also intervenes in the testing process simultaneously. The submersible pump in the mud preparation tank is started and pumps the prepared high-concentration mud liquid through a flexible hose to the annular spray pipe fitted on the outside of the wheel hub motor assembly under test. Several oblique nozzles on the inner wall of the annular spray pipe spray high-speed mud jets into the radial direction of the wheel hub motor assembly under test at a 45-degree angle. The 45-degree angled jets allow the mud to both flush the motor gaps axially and impact the rotating surface tangentially, thus simulating the erosion effect of mud on the motor seals and heat sinks when the vehicle is driving on a muddy road. After flushing, the mud falls into the drainage trough at the bottom of the environmental simulation chamber and flows back to the mud preparation tank through the feed pipe to form a cycle or discharge.

[0044] The horizontal movement and vertical lifting motion of the gantry support always follow the motion trajectory of the multi-degree-of-freedom excitation platform to ensure that the contact point between the roller loading assembly and the tire tread does not slip. The force sensor continuously corrects the stroke of the vertical lifting cylinder during severe vibration to compensate for the distance changes caused by simulated road vibration. The built-in brake dynamically adjusts the magnitude and frequency of the resistance torque according to the preset extreme working condition sequence to simulate torque fluctuations during rapid acceleration and deceleration. The emission frequency of the electromagnetic acceleration coil is synchronized with the rotation phase of the wheel hub motor assembly under test to ensure that the gravel always hits the specific weak area of ​​the motor housing. The spray pressure of the angled nozzle is automatically adjusted according to the speed of the wheel hub motor assembly under test to maintain a constant relative scouring intensity.

[0045] In one specific implementation, the data acquisition system includes an embedded main control unit, a high-frequency current transformer, a three-phase voltage sampling module, a six-dimensional force sensor array, a fiber optic temperature sensor network, and a high-speed industrial camera. The high-frequency current transformer is sleeved on the three-phase input cable of the hub motor assembly under test. The six-dimensional force sensor array is embedded between the upper clamping flange and the mounting interface of the hub motor assembly under test. The fiber optic temperature sensor network is attached to the stator winding end and the outer ring surface of the bearing of the hub motor assembly under test. The high-speed industrial camera is aimed at the air gap position of the hub motor assembly under test through a transparent observation window. The execution logic of the extreme working condition sequence is as follows: First, the multi-degree-of-freedom excitation platform is started, causing the lower translation module to... The system performs a sinusoidal reciprocating motion of ±50mm at a frequency of 0.5Hz, while the middle rotating module oscillates at a frequency of ±30 degrees at a frequency of 1Hz. Then, the environmental simulation chamber is activated, and a mixture of ice and water at a temperature of -40℃ is sprayed through a high-pressure atomizing nozzle for 10 minutes, followed by switching to high-temperature steam at 85℃ for 20 minutes. During this period, the gravel impact simulation subsystem is activated simultaneously, and the electromagnetic acceleration coil is controlled to launch ceramic projectiles with a diameter of 10mm at a frequency of 5 shots per second. Finally, the roller loading component of the load loading mechanism is controlled to apply a resistance torque from 0 to 90% of the peak torque in a step manner, and a pulsating torque with a frequency of 20Hz and an amplitude of 10% of the peak torque is superimposed during the peak holding phase.

[0046] In a specific application of this invention, a high-frequency current transformer is mounted on the three-phase input cable of the hub motor assembly under test and senses the alternating magnetic field inside the cable in real time, thereby converting the large current signal into a weak voltage signal and transmitting it to the main control unit to capture the current harmonic distortion rate of the motor under severe load fluctuations. The three-phase voltage sampling module is directly connected in parallel to the motor input terminal and synchronously records the phase voltage amplitude and phase angle at each moment to calculate the instantaneous power factor. The six-dimensional force sensor array is precisely embedded between the upper clamping flange and the mounting interface of the hub motor assembly under test, thus becoming the only force transmission channel between the two.

[0047] When the multi-degree-of-freedom excitation platform starts and drives the lower translation module to perform a large-stroke sinusoidal reciprocating motion of ±50mm at a frequency of 0.5Hz according to the preset logic, the six-dimensional force sensor array instantly senses the huge inertial force from the horizontal direction and the impact load caused by the acceleration change. At the same time, the middle rotation module performs a large-amplitude swing of ±30 degrees at a frequency of 1Hz to simulate the edge conditions of a vehicle's sharp turn or rollover. At this time, the six-dimensional force sensor array can also calculate the forces and torques acting on the motor shaft in three directions to evaluate the dynamic stiffness of the installation structure. The fiber optic grating temperature sensor network is tightly attached to the stator winding end and bearing outer ring surface of the hub motor assembly under test and uses the physical characteristics of light wavelength changing with temperature to monitor the hot spot temperature in real time.

[0048] When the environmental simulation chamber is opened and a mixture of ice and water at -40°C is sprayed into the chamber through a high-pressure atomizing nozzle, the fiber optic grating temperature sensor network records the process of the motor housing surface temperature dropping sharply within 10 minutes and captures the minute deformation caused by thermal stress inside the winding due to the different thermal expansion coefficients of the materials. Subsequently, the control system switches the air source to spray high-temperature steam at 85°C through the high-pressure atomizing nozzle for 20 minutes. The fiber optic grating temperature sensor network continues to track the temperature recovery curve and monitor the performance degradation signs of the insulation material under alternating hot and cold shocks.

[0049] A high-speed industrial camera focuses its lens on the air gap of the hub motor assembly under test through a transparent observation window on the environmental simulation chamber and continuously captures the relative motion between the rotor and stator at a high frame rate. When the gravel impact simulation subsystem is started synchronously and the electromagnetic acceleration coil fires ceramic projectiles with a diameter of 10mm at a frequency of 5 shots per second to impact the motor housing, the high-speed industrial camera captures the micron-level vibration displacement generated at the moment of impact on the housing and the dynamic change in the air gap width to determine whether the rotor is at risk of rubbing. At the same time, the roller loading component of the load loading mechanism applies a huge resistance torque from 0 to 90% of the peak torque in a step manner. The high-frequency current transformer records the transient process of the current surge. When the resistance torque reaches the peak and is maintained, the system superimposes a pulsating torque with a frequency of 20Hz and an amplitude of 10% of the peak torque to simulate the torque fluctuation caused by high-frequency bumps on the road surface.

[0050] At this stage, the six-dimensional force sensor array detects the high-frequency alternating force component superimposed on the average load, the fiber optic temperature sensor network monitors the further rise in winding temperature due to increased copper loss, and the embedded main control unit aligns and fuses all these high-frequency data from different sensors on the time axis. The system identifies potential electromagnetic faults by analyzing the correlation between current waveform and vibration spectrum, evaluates the ultimate capacity of the heat dissipation system by comparing the hysteresis of temperature change rate and load curve, and judges the stability of mechanical structure by observing the correspondence between air gap image captured by high-speed camera and six-dimensional force data.

[0051] In one specific embodiment, the system further includes an online sealing performance monitoring unit, which comprises a tracer gas generator, a mass spectrometer leak detector, and a negative pressure suction hood. The tracer gas generator is connected to the air inlet of the environmental simulation chamber and is used to fill the environmental simulation chamber with a mixture of helium and air. The negative pressure suction hood is fastened to the outside of the bearing sealing cover of the hub motor assembly under test. The negative pressure suction hood is connected to the air intake of the mass spectrometer leak detector through a sampling tube. When the helium concentration in the environmental simulation chamber reaches a preset threshold, the negative pressure suction hood is activated and gas is drawn into the mass spectrometer leak detector at a constant flow rate for analysis.

[0052] In a specific application of this invention, the tracer gas generator first starts and continuously supplies a mixture of helium and air to the air inlet of the environmental simulation chamber. Due to its extremely small atomic diameter and strong penetrating ability, the helium molecules quickly diffuse and distribute evenly within the environmental simulation chamber. When the helium concentration sensor in the environmental simulation chamber detects that the gas concentration has reached a preset safety threshold, the control system immediately instructs the online monitoring unit for sealing performance to enter the working state. At this time, the negative pressure suction hood is tightly fastened to the outside of the bearing sealing cover of the wheel hub motor assembly under test and forms a partially enclosed space. The vacuum pump extracts gas from inside the negative pressure suction hood at a constant flow rate through the sampling tube, so that the gas pressure inside the negative pressure suction hood is lower than the background gas pressure in the environmental simulation chamber, thereby establishing a stable pressure difference between the inner and outer surfaces of the bearing sealing cover.

[0053] If the bearing seal of the hub motor assembly under test has tiny cracks, pores, or assembly gaps, the high concentration of helium molecules in the environmental simulation chamber will be driven by the pressure difference to pass through the defect and enter the internal cavity of the bearing. Subsequently, these leaking helium molecules are captured by the airflow generated by the negative pressure suction hood and flow at high speed along the sampling tube to the intake port of the mass spectrometer leak detector. The ion source inside the mass spectrometer leak detector ionizes the helium atoms in the intake gas into positively charged helium ions. The magnetic field separates the helium ions from other gas ions according to the specific mass-to-charge ratio of the helium ions and guides them to the detector. The detector converts the helium ion flow into an electrical signal and displays the leakage rate value in real time. Because the background content of helium in the air is extremely low and its chemical properties are stable, the mass spectrometer leak detector can identify even extremely small amounts of helium signals, thereby quantifying the degree of seal failure.

[0054] Throughout the testing process, the multi-degree-of-freedom excitation platform continuously outputs composite vibration signals, causing high-frequency vibrations in the tested hub motor assembly. The mechanical vibration dynamically expands the microscopic defects in the seals, thereby increasing the helium leakage flux. Simultaneously, the drastic temperature changes within the environmental simulation chamber cause thermal expansion and contraction of the sealing rubber material, which in turn alters the clamping force of the sealing contact surface. The negative pressure suction hood, through a flexible connection structure, automatically adjusts its position to follow the movement trajectory of the tested hub motor assembly to maintain tightness and prevent external air from mixing in and interfering with the test results. The inner wall of the sampling pipeline undergoes special polishing treatment to reduce the adsorption and retention of helium molecules and ensure the real-time nature of the detection response. The mass spectrometer leak detector performs time-synchronous correlation analysis with the collected leakage rate data and the current vibration amplitude, temperature value, and load torque.

[0055] The system determines whether the seals are fatigued and loose by observing the fluctuation characteristics of the leakage rate as a function of vibration frequency. It locates the aging failure temperature range of the sealing material by analyzing the abrupt change points of the leakage rate during temperature cycling. The online monitoring method avoids the risk of residual moisture corroding the internal components of the motor in traditional water testing methods. It also overcomes the limitation of static leak detection in reflecting the sealing performance under dynamic operating conditions. The tracer gas generator, negative pressure suction hood, and mass spectrometer leak detector form a closed-loop detection system through airflow path and signal feedback. The system monitors the sealing integrity assessment of the hub motor assembly under test in real time in the extreme test environment of multi-physics coupling, ensuring that any minor sealing failure can be captured and recorded before it causes water ingress or grease loss inside the motor.

[0056] In one specific implementation, a real-time correction module based on digital twins is also included. The real-time correction module includes a local server, a 3D modeling engine, and a feedback controller. The local server communicates with the data acquisition system via gigabit Ethernet to receive real-time electrical parameters, mechanical vibration parameters, and thermal imaging data. The 3D modeling engine runs a finite element model of the hub motor assembly under test on the local server and maps the real-time data to the corresponding nodes of the finite element model to calculate the stress concentration factor and the predicted temperature rise. When the stress concentration factor exceeds the safety threshold or the predicted temperature rise exceeds the insulation level limit, the feedback controller sends a load reduction command to the multi-degree-of-freedom excitation platform, environmental simulation chamber, or load loading mechanism to adjust the vibration amplitude, ambient temperature, or resistance torque.

[0057] In specific applications of this invention, the local server continuously receives massive real-time data streams from high-frequency current transformers, a six-dimensional force sensor array, and a fiber optic temperature sensor network. The 3D modeling engine loads a high-precision finite element model of the hub motor assembly under test within the local server and maps the received discrete sensor data to the corresponding mesh nodes of the finite element model through an interpolation algorithm. The 3D modeling engine uses the mapped boundary conditions to solve the thermal and mechanical coupling equations in real time to calculate the stress distribution and temperature field evolution trend of each tiny unit inside the motor. The 3D modeling engine pays special attention to the stress concentration factor and temperature rise prediction value of key parts such as the stator winding ends, bearing raceways, and housing connections.

[0058] When the stress concentration factor calculated by the 3D modeling engine exceeds the safety threshold of the material's yield strength, the feedback controller immediately intervenes. The feedback controller generates a load reduction command based on the severity of the over-limit and sends it to the multi-degree-of-freedom vibration platform or load loading mechanism via the network. After receiving the command, the multi-degree-of-freedom vibration platform quickly reduces the amplitude of the sinusoidal reciprocating motion of the lower translation module or reduces the oscillation frequency of the middle rotation module to alleviate mechanical shock. Alternatively, the vertical lifting cylinder in the load loading mechanism slightly retracts to reduce the normal pressure of the roller loading component on the tire, thereby reducing the torque load transmitted to the motor shaft.

[0059] When the 3D modeling engine predicts that the winding hot spot temperature is about to exceed the heat resistance limit of the insulation material, the feedback controller sends an adjustment command to the environmental simulation chamber. The environmental simulation chamber then shuts off the high-temperature steam source and increases the spray ratio of the low-temperature ice-water mixture in the high-pressure atomizing nozzle to accelerate heat dissipation. At the same time, the feedback controller also instructs the built-in brake in the load loading mechanism to reduce the resistance torque to reduce the copper loss heat generation inside the motor. The dynamic adjustment mechanism based on real-time calculation results makes the test process no longer blindly execute the preset program.

[0060] Adaptive control is implemented based on the actual load-bearing capacity and real-time status of the hub motor assembly under test. The local server continuously compares the deviation between the measured data and the simulation prediction values ​​and uses historical data to correct the material parameters of the finite element model to improve the accuracy of subsequent calculations. The 3D modeling engine transforms the invisible internal stress field and temperature field into a visualized cloud map for operators to monitor. The feedback controller completes closed-loop control from data reception and logical judgment to command issuance within milliseconds to prevent irreversible damage to the hub motor assembly under test before it reaches destructive failure.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0062] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A comprehensive performance evaluation and testing method for hub motor assembly under extreme operating conditions, characterized in that, Includes the following steps: Step 1: Construct a test bench, which includes a base, a multi-degree-of-freedom excitation platform set on the base, an environmental simulation chamber located above the multi-degree-of-freedom excitation platform, and a load loading mechanism set inside the environmental simulation chamber. Step 2: Fix the hub motor assembly under test at the center position of the multi-degree-of-freedom vibration platform, so that the wheel axle centerline of the hub motor assembly under test coincides with the rotation center of the multi-degree-of-freedom vibration platform; Step 3: Connect the interior of the environmental simulation chamber to the external medium source through a piping system, which includes a coolant circulation pipe, a spray pipe, and a gas replacement pipe; Step 4: The output end of the load loading mechanism contacts the tread of the tire of the wheel hub motor assembly under test to form a friction transmission pair; Step 5: Under the preset extreme working condition sequence, the multi-degree-of-freedom excitation platform is synchronously controlled to generate composite vibration signals, the environmental simulation chamber adjusts the temperature, humidity and medium concentration, the load loading mechanism applies dynamic resistance torque, and the electrical parameters, mechanical vibration parameters and thermal imaging data of the hub motor assembly under test are collected in real time.

2. The comprehensive performance evaluation and testing method for hub motor assembly under extreme operating conditions according to claim 1, characterized in that, The multi-degree-of-freedom vibration platform includes a lower translation module, a middle rotation module, and an upper clamping flange. The lower translation module is slidably connected to the top surface of the base via a first linear guide pair. The middle rotation module is mounted on the center of the top surface of the lower translation module via a slewing bearing. The upper clamping flange is radially slidably connected to the top surface of the middle rotation module via a second linear guide pair. The center of the upper clamping flange has a mounting through hole for the hub motor assembly to be tested. Four hydraulic locking claws are evenly distributed circumferentially on the inner wall of the mounting through hole, and each hydraulic locking claw has an arc-shaped contact surface at its end.

3. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 2, characterized in that, The environmental simulation chamber has a double-layered hollow structure, including an inner chamber and an outer chamber, with a heat-insulating cavity formed between the inner and outer chambers. The bottom of the inner chamber is provided with a drainage channel, and the lowest point of the drainage channel is connected to a waste liquid collection tank through a one-way valve. Twelve high-pressure atomizing nozzles are evenly arranged along the circumference on the inner side of the top of the inner chamber. The spray angle of each high-pressure atomizing nozzle is adjustable, and the inlet end of the high-pressure atomizing nozzle is connected to a high-temperature steam source and a low-temperature ice-water mixture source through a three-way valve.

4. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 3, characterized in that, The load loading mechanism includes a gantry support, a horizontal moving slide, a vertical lifting cylinder, and a roller loading assembly. The gantry support spans above the environmental simulation chamber. The horizontal moving slide reciprocates along the crossbeam of the gantry support via a gear and rack mechanism. The vertical lifting cylinder is fixed to the bottom of the horizontal moving slide. The roller loading assembly is suspended from the piston rod end of the vertical lifting cylinder via a force sensor. The roller loading assembly includes a loading roller, a built-in brake, and a high-inertia flywheel. The outer surface of the loading roller is covered with a replaceable friction coefficient adjustment layer.

5. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 4, characterized in that, It also includes a crushed stone impact simulation subsystem, which includes a storage hopper, a screw feeder, an acceleration pipe, and an impact target area. The storage hopper is located at a high external position outside the environmental simulation chamber. The inlet end of the acceleration pipe is connected to the outlet of the screw feeder, and the outlet end of the acceleration pipe passes through the side wall of the environmental simulation chamber and points to the lower half of the hub motor assembly under test. Three electromagnetic acceleration coils are arranged axially at intervals inside the acceleration pipe. The impact target area is located directly below the hub motor assembly under test, and a grid-shaped rebound baffle is provided at the bottom of the impact target area.

6. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 5, characterized in that, It also includes a combined mud and water soaking and flushing module, which includes a mud preparation tank, a submersible pump, and an annular spray pipe. The mud preparation tank is connected to a drainage trough at the bottom of the environmental simulation chamber through a feed pipe. The submersible pump is immersed in the mud liquid in the mud preparation tank. The outlet of the submersible pump is connected to the annular spray pipe through a flexible hose. The annular spray pipe is sleeved on the outside of the hub motor assembly under test. Several oblique nozzles are evenly distributed on the inner wall of the annular spray pipe facing the hub motor assembly under test. The axis of the oblique nozzles forms a 45-degree angle with the radial direction of the hub motor assembly under test.

7. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 6, characterized in that, The data acquisition system includes an embedded main control unit, a high-frequency current transformer, a three-phase voltage sampling module, a six-dimensional force sensor array, a fiber optic temperature sensor network, and a high-speed industrial camera. The high-frequency current transformer is sleeved on the three-phase input cable of the hub motor assembly under test. The six-dimensional force sensor array is embedded between the upper clamping flange and the mounting interface of the hub motor assembly under test. The fiber optic temperature sensor network is attached to the stator winding end and the outer ring surface of the bearing of the hub motor assembly under test. The high-speed industrial camera is aimed at the air gap position of the hub motor assembly under test through a transparent observation window.

8. The comprehensive performance evaluation and testing method for hub motor assembly under extreme operating conditions according to claim 7, characterized in that, The execution logic of the extreme working condition sequence is as follows: First, the multi-degree-of-freedom excitation platform is started, causing the lower translation module to perform a sinusoidal reciprocating motion of ±50mm at a frequency of 0.5Hz, while the middle rotation module swings at a frequency of 1Hz and ±30 degrees. Then, the environmental simulation chamber is turned on, and a mixture of ice and water at a temperature of -40℃ is sprayed through a high-pressure atomizing nozzle for 10 minutes, followed by switching to high-temperature steam at 85℃ for 20 minutes. During this period, the gravel impact simulation subsystem is started simultaneously, and the electromagnetic acceleration coil is controlled to launch ceramic projectiles with a diameter of 10mm at a frequency of 5 shots per second. Finally, the roller loading component of the load loading mechanism is controlled to apply a resistance torque from 0 to 90% of the peak torque in a step manner, and a pulsating torque with a frequency of 20Hz and an amplitude of 10% of the peak torque is superimposed during the peak holding phase.

9. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 8, characterized in that, It also includes an online sealing performance monitoring unit, which includes a tracer gas generator, a mass spectrometer leak detector, and a negative pressure suction hood. The tracer gas generator is connected to the air inlet of the environmental simulation chamber and is used to fill the environmental simulation chamber with a mixture of helium and air. The negative pressure suction hood is fastened to the outside of the bearing sealing cover of the hub motor assembly under test. The negative pressure suction hood is connected to the air intake of the mass spectrometer leak detector through a sampling tube. When the helium concentration in the environmental simulation chamber reaches a preset threshold, the negative pressure suction hood is activated and gas is drawn into the mass spectrometer leak detector at a constant flow rate for analysis.

10. The comprehensive performance evaluation and testing method for hub motor assembly under extreme working conditions according to claim 9, characterized in that, It also includes a real-time correction module based on digital twins. The real-time correction module includes a local server, a 3D modeling engine, and a feedback controller. The local server communicates with the data acquisition system via gigabit Ethernet to receive real-time electrical parameters, mechanical vibration parameters, and thermal imaging data. The 3D modeling engine runs a finite element model of the hub motor assembly under test on the local server and maps the real-time data to the corresponding nodes of the finite element model to calculate the stress concentration factor and the predicted temperature rise. When the stress concentration factor exceeds the safety threshold or the predicted temperature rise exceeds the insulation level limit, the feedback controller sends a load reduction command to the multi-degree-of-freedom excitation platform, environmental simulation chamber, or load loading mechanism to adjust the vibration amplitude, ambient temperature, or resistance torque.

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