Microscopic dimension analysis and evaluation method for stator assembly of vehicle drive motor

Abstract

The present application relates to the technical field of new energy automobile driving motor stator assembly, in particular to a micro size analysis and evaluation method for vehicle driving motor stator assembly, which comprises the following steps: before the stator assembly is assembled, the micro size of the stator tooth space is accurately measured, then the micro size of the tooth space is subjected to Fourier decomposition and analysis, the stability coefficients of the second-order component and the high-order component of the micro size are calculated in sequence, the comprehensive evaluation coefficient of the micro size of the stator assembly is obtained by integration, and the score and risk rating are completed according to the preset grading standard. The method realizes the quantitative analysis and early risk prediction of the micro size of the stator tooth, can effectively avoid the problems of noise deterioration, layered deformation and scanning failure after assembly, reduces the waste of samples, shortens the detection period and improves the assembly reliability of the motor.

Description

Technical Field

[0001] This invention relates to the field of stator assembly technology for drive motors in new energy vehicles, specifically to a method for microscopic dimensional analysis and evaluation of automotive drive motor stator assemblies. Background Technology

[0002] In new energy vehicle drive motors, the stator assembly is a core component of the power output unit. Its structural precision and dimensional consistency directly determine the overall performance, operational stability, and service life of the drive motor, forming the core foundation for ensuring its long-term reliable operation. Among these components, the stator teeth, as a core functional part of the stator assembly, have a decisive impact on the uniformity and consistency of the air gap between the stator and rotor in both radial and circumferential directions due to their microscopic dimensional precision. Furthermore, the uniformity of the air gap between the stator and rotor is a crucial prerequisite for ensuring the motor's electromagnetic performance (such as magnetic field distribution and electromagnetic induction efficiency), mechanical performance (such as smooth operation), and noise and vibration levels. Insufficient air gap uniformity will directly lead to abnormal motor operation, affecting the vehicle's power output and driving experience.

[0003] In the actual production process of drive motors, the micro-dimensions of the stator assembly teeth are prone to deviations, fluctuations, or unevenness. These dimensional abnormalities will trigger a series of adverse effects, seriously damaging the quality and reliability of the drive motor and electric drive assembly. The specific analysis is as follows:

[0004] 1. Microscopic dimensional deviations in the stator assembly teeth can disrupt the uniformity of the air gap between the stator and rotor, leading to uneven distribution of the magnetic field inside the motor. This significantly worsens the electromagnetic noise performance of the electric drive assembly, exacerbates vibration and noise during motor operation, reduces passenger comfort, accelerates wear on internal motor components, and shortens the lifespan of the drive motor.

[0005] 2. The stator assembly and the motor housing are usually fixedly connected by a thermal fitting process. If there are abnormalities in the micro-dimensions of the stator teeth, it will lead to assembly defects such as loose fit, delamination, and excessive gaps at the interface between the stator assembly and the housing. This will reduce the overall structural rigidity of the motor, directly affect the torque transmission efficiency and output capability of the motor, and cause a decline in the motor's power performance.

[0006] 3. When the micro-dimensional deviation of the stator teeth is too large, under the operating conditions of the motor running and the rotor rotating at high speed, the rotor is very likely to directly contact and rub against the stator teeth, causing a motor rubbing failure. This rubbing failure will not only cause direct damage to the stator and rotor components, but also lead to the failure of the entire electric drive assembly, and may even cause safety hazards such as power interruption in new energy vehicles, seriously threatening the personal safety of drivers and passengers.

[0007] To address the aforementioned technical problems caused by microscopic dimensional deviations in stator teeth, the conventional method for detecting the microscopic dimensions of stator assembly teeth in the prior art involves indirectly inferring whether there are any abnormalities in the microscopic dimensions of the stator teeth by inspecting macroscopic dimensional parameters such as roundness and cylindricity of the motor housing after all assembly processes of the stator assembly and motor housing have been completed. However, after long-term application, those skilled in the art have found that this dimensional detection method has significant technical limitations and shortcomings, as detailed below:

[0008] (1) Low detection efficiency and high cost

[0009] This inspection method requires all assembly processes to be completed before testing can be carried out, resulting in a long inspection cycle and cumbersome operation. Once microscopic anomalies are found in the stator teeth during inspection, the assembled parts cannot be reused, causing a large waste of samples and significantly increasing production costs.

[0010] (2) Insufficient detection accuracy

[0011] Since there is no precise correspondence between the micro-dimensional dimensions of the stator teeth and the macro-dimensional dimensions of the motor housing, this detection method indirectly infers the micro-dimensional dimensions of the stator teeth by using the macro-dimensional dimensions of the motor housing. This results in a large detection error and cannot accurately reflect the true deviation of the micro-dimensional dimensions of the stator teeth, making it difficult to meet the requirements of high-precision production of drive motors.

[0012] (3) Weak risk management capabilities

[0013] This detection method can only detect microscopic anomalies in the stator teeth after final assembly. It cannot accurately quantify and predict the operational risks caused by microscopic deviations in the stator teeth, making it difficult to effectively control the quality and reliability of the drive motor and hindering the improvement of the overall performance and quality of drive motors in new energy vehicles.

[0014] Therefore, in the context of the upgrading and iteration of new energy vehicles towards high performance, high reliability and long service life, how to accurately detect the micro-dimensional deviations of the stator assembly teeth, ensure the uniformity of the air gap between the stator and rotor, and effectively improve detection efficiency, reduce detection costs and strengthen operational risk management has always been a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0015] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for micro-dimensional analysis and evaluation of stator assemblies for automotive drive motors. This method enables precise detection, Fourier analysis, and quantitative evaluation of the micro-dimensional dimensions of stator teeth before stator assembly, effectively avoiding problems such as electromagnetic noise deterioration, thermal sleeve delamination, and motor stator rubbing. It also effectively improves detection efficiency, reduces production costs, and enables early prediction and control of drive motor operation risks.

[0016] The objective of this invention is achieved through the following approach:

[0017] A method for microscopic dimensional analysis and evaluation of automotive drive motor stator assembly includes the following steps:

[0018] 1) At both ends of the axial direction of each vehicle drive motor stator assembly, the micro-dimensions of the stator tooth space are detected to obtain the coordinate data of two feature points for each tooth;

[0019] 2) Based on the coordinate data obtained in step 1), Fourier analysis is performed on the micro-dimensions of the stator tooth space to obtain the amplitudes of each order of Fourier components of the micro-dimensions of the tooth space at end face A and end face B of the stator assembly.

[0020] 3) Based on the amplitudes of each Fourier component obtained in step 2), the comprehensive evaluation coefficients of the micro-size of the stator assembly are obtained;

[0021] 4) Based on the comprehensive evaluation coefficient obtained in step 3), the micro-dimensional scoring results and risk rating results of the automotive drive motor stator assembly are obtained according to the preset theoretical grading standards.

[0022] Preferably, in step 1), the number of vehicle drive motor stator assemblies is ≥10.

[0023] Preferably, in step 1), when detecting the micro-dimensional dimensions of the stator tooth space, the cross-section 5mm axially inside the A end face and the cross-section 5mm axially inside the B end face are used as the measurement planes.

[0024] Preferably, in step 1), the detection method for the coordinate data of the two feature points of each tooth is as follows:

[0025] On the measurement planes of end face A and end face B of the stator assembly, randomly select a tooth, take the center point of the tooth as the positioning reference, take the geometric center of the stator as the center, and take the distance from the geometric center of the stator to the center point of the tooth as the radius, draw 180° / Z degree arcs in the positive and negative directions respectively, and obtain the coordinates of the two arc endpoints, which are the coordinate data of the two feature points of the tooth.

[0026] Preferably, in step 2), the amplitudes of each order of the Fourier components of the micro-dimensional space of the teeth on end face A and end face B of the stator assembly are calculated according to the following formulas:

[0027] 2-1) Measurement plane at end A

[0028] ;

[0029] ;

[0030] ;

[0031] In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space on end face A of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the A end face of the stator assembly. The number of stator teeth. For the measurement plane of end face A of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face A of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face A, the first Feature points axis coordinate values, For measuring the plane of end face A, the first Feature points axis coordinate values, This refers to the inner diameter of the stator teeth.

[0032] 2-2) Measurement plane of end face B

[0033] ;

[0034] ;

[0035] ;

[0036] In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space at end face B of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the B end face of the stator assembly. The number of stator teeth. For the measurement plane of end face B of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face B of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face B Feature points axis coordinate values, For measuring the plane of end face B Feature points axis coordinate values, This refers to the inner diameter of the stator teeth.

[0037] Preferably, in step 3), the comprehensive evaluation coefficient of the micro-size of the stator assembly is obtained as follows:

[0038] 3-1) Based on the amplitudes of each Fourier component obtained in step 2), calculate the second-order component stability coefficients of the spatial micro-dimensions of the toothed parts on the A-end face and B-end face of the stator assembly, respectively.

[0039] 3-2) Based on the amplitudes of each Fourier component obtained in step 2), calculate the stability coefficients of the higher-order components of the micro-dimensional space of the tooth section on the A-end face and B-end face of the stator assembly, respectively.

[0040] 3-3) Based on the second-order component stability coefficient obtained in step 3-1) and the higher-order component stability coefficient obtained in step 3), the comprehensive evaluation coefficient of the micro-size of the stator assembly is calculated.

[0041] Preferably, in step 3-1), the second-order component stability coefficients of the spatial micro-dimensions of the planar teeth on the A and B end faces of the stator assembly are calculated according to the following formula:

[0042] + ;

[0043] + ;

[0044] ;

[0045] ;

[0046] In the formula, The number of stator assembly samples. For all samples, measure the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions at the A end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the A-end face of the stator assembly for all samples. This is the sample number of the stator assembly. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the second-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions was measured at the B end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the B end face of the stator assembly for all samples. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section is measured at the B end face of the stator assembly for all samples.

[0047] Preferably, in step 3-2), the higher-order component stability coefficients of the spatial micro-dimensions of the measuring planar teeth on the A and B end faces of the stator assembly are calculated according to the following formula:

[0048] + ;

[0049] + ;

[0050] ;

[0051] ;

[0052] In the formula, For higher-order Fourier series from 3 to 10, The number of stator assembly samples. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at end face A of the stator assembly. For all samples, measure the higher-order variance coefficients of the planar tooth space micro-dimensions on the A end face of the stator assembly. This is the sample number of the stator assembly. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at the B end face of the stator assembly. The higher-order variance coefficients of the planar tooth space micro-dimensions were measured for the stator assembly B end face for all samples. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

[0053] Preferably, in step 3-3), the comprehensive evaluation coefficient of the micro-dimensional structure of the stator assembly is calculated according to the following formula:

[0054] ;

[0055] In the formula, DWZ is the comprehensive evaluation coefficient of the micro-size of the stator assembly, MAX is the function for maximizing the value, and MIN is the function for minimizing the value. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly A end face tooth section for all samples. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples. The order of the higher-order Fourier components of the microscopic dimensions of the teeth on the A and B end faces of the stator assembly is given. For all samples, the higher-order component stability coefficients of the micro-dimensional space of the stator assembly A end face tooth section are given. R is the higher-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples, and R is the inner diameter of the stator tooth.

[0056] Preferably, in step 4), the theoretical grading criteria include:

[0057] DWZ≥2.8, score 1, micro-scale risk out of control;

[0058] 2.0≤DWZ<2.8, score 2 points, indicating a high risk in micro-scale dimensions;

[0059] 1.6≤DWZ<2.0, score 3, there is a risk in micro-scale analysis;

[0060] 1.2≤DWZ<1.6, score 4, good microstructure;

[0061] DWZ < 1.2, rating 5 points, excellent micro-size.

[0062] The beneficial effects of this invention are as follows:

[0063] 1. This invention enables full-dimensional quantitative detection and risk assessment of the micro-dimensions of the teeth in the unassembled stator assembly state, thereby avoiding potential motor failures at the source.

[0064] Before the stator assembly is assembled with the housing, this invention can acquire precise spatial position data of the stator teeth by using dual-plane fixed-point coordinate acquisition on the A-end face -5mm measurement plane and the B-end face -5mm measurement plane. The dimensional signal standardization processing is completed by the spatial displacement sequence Si and the spatial angle sequence Di. This enables early and accurate identification of dimensional defects that may lead to serious failures such as electromagnetic noise deterioration, heat sleeve delamination, core deformation, and rotor rubbing. This improves the operational safety, structural reliability, and durability of the drive motor from the source of research and development and manufacturing.

[0065] 2. This invention constructs a frequency domain decomposition method for microscopic dimensions based on Fourier transform, achieving high-precision analysis of the size signal and accurate extraction of its components.

[0066] This invention uses Fourier transform to perform frequency domain decomposition on spatial displacement sequences, which can separate the continuous and complex microscopic dimensional fluctuations in the circumferential direction of stator teeth into first-order components, second-order components, and higher-order components of orders 3 to 10, thereby clearly distinguishing three different types of dimensional deviations:

[0067] The first-order low-frequency component is formed by the overall positional offset of the inner circle of the stator relative to the geometric center;

[0068] The second-order component is formed by the elliptic deformation of the inner circle of the stator;

[0069] The higher-order components are formed by the local minute dimensional fluctuations of the teeth caused by factors such as lamination processing, core stacking, and welding processes.

[0070] This invention can identify micro-scale fluctuations at the micrometer level, effectively suppress spectral leakage during frequency domain decomposition, and has significantly better evaluation accuracy than traditional macroscopic geometric measurement methods. It realizes a technological upgrade from "macroscopic shape judgment" to "microscopic frequency domain component analysis", providing a calculable, traceable, and quantifiable scientific basis for evaluating the micro-scale quality of automotive drive motor stator assemblies.

[0071] Meanwhile, by effectively identifying and controlling the second-order and higher-order components, this invention can ensure the uniformity of the stator's inner roundness and tooth size distribution, stabilize the air gap magnetic field between the stator and rotor, and reduce fluctuations in electromagnetic torque and radial electromagnetic force, thereby suppressing electromagnetic noise at the dimensional source. Experimental verification shows that using a stator assembly that meets the evaluation criteria of this invention can control the electromagnetic noise degradation to within 3dB, effectively avoiding noise degradation exceeding 6dB or even 10dB due to dimensional fluctuations. This significantly improves the NVH performance of the drive motor and further enhances the overall quietness and driving experience of new energy vehicles.

[0072] 3. This invention conducts batch statistical calculations based on ≥10 sets of stator samples, which can truly reflect the stability of batch manufacturing, and the evaluation results are more representative and reliable.

[0073] This invention does not rely on a single sample for judgment. Instead, it conducts statistical analysis using the Fourier component results of ≥10 sets of stator assembly samples. The variance coefficient is calculated using methods such as average value, variance summation, and square root operation. A stability coefficient is constructed by combining the maximum value of the components. This objectively reflects the dimensional fluctuation range and consistency level of products in the same batch during processing, stacking, and shaping. It avoids misjudgments caused by the randomness of a single sample and provides real, reliable, and quantifiable data support for mass production process stability evaluation, tooling and mold optimization, and stamping quality control.

[0074] 4. This invention proposes a comprehensive evaluation coefficient for the micro-dimensional dimensions of the stator assembly, achieving multi-dimensional index fusion and intuitive risk rating.

[0075] This invention normalizes and integrates multiple key indicators, including the second-order and higher-order stability coefficients of the stator assembly's two end faces, the comparison deviation term of the two end faces, and the stator inner diameter R, to form a unique comprehensive evaluation coefficient. It also establishes a 1-5 point quantitative scoring system with corresponding risk level standards, directly determining five levels: "Excellent Microscopic Dimensions," "Good," "Riskful," "Significant Risk," and "Out of Control Risk," clearly identifying the corresponding noise degradation magnitude, heat jacket delamination risk, and rotor rubbing probability. The evaluation results do not require in-depth interpretation by professionals; production, quality, and R&D personnel can quickly determine whether assembly is feasible, whether optimization is needed, and the optimization priority, thus achieving standardized testing procedures, clear judgment rules, and proactive risk control.

[0076] 5. This invention significantly reduces research and development and manufacturing costs, shortens the development cycle, reduces material and labor waste, and yields outstanding economic benefits.

[0077] This invention allows for evaluation at the stator semi-finished stage, eliminating the need for defective parts to proceed to subsequent processes, directly saving on heat fitting costs, impregnation costs, winding costs, and labor costs. Simultaneously, this invention can quickly pinpoint the source of dimensional issues, avoiding the need for rectification of vehicle-wide noise and vibration problems. Practical application verification shows that this invention can shorten the evaluation cycle by more than 40%, reduce sample loss and manufacturing costs by more than 50%, and significantly improve the efficiency of drive motor development and mass production yield.

[0078] 6. This invention can precisely pinpoint the source of dimensional defects, providing a clear direction for process optimization and enabling an upgrade from passive detection to proactive prevention.

[0079] This invention can directly determine the specific link in the dimensional problem by analyzing the numerical difference between the second-order component stability coefficient and the higher-order component stability coefficient.

[0080] If the second-order component is abnormal, it indicates that the overall ellipticity of the stator is large, and the lamination, shaping, and bulging processes need to be optimized; if the higher-order component is abnormal, it indicates that the local fluctuations of the teeth are large, and the lamination accuracy, welding process, or lamination tooling needs to be optimized.

[0081] Through the above analysis, this invention enables the micro-dimensional optimization of automotive drive motor stator assemblies to no longer rely on experience-based judgment, but rather to accurately distinguish defect types based on quantitative data and point to the optimization direction, realizing the transformation from "passive detection" to "proactive prevention and precise improvement", effectively improving the debugging efficiency of the process and the control capability of dimensional consistency.

[0082] 7. This invention has strong versatility and wide applicability, and can be applied to the dimensional evaluation of stator assemblies for drive motors in various new energy vehicles.

[0083] This invention uses the number of stator teeth Z and the inner diameter of the stator teeth R as basic structural parameters. It does not rely on specific motor power, pole-slot fit, or stator outer diameter, and can be widely applied to the micro-dimensional evaluation of stator assemblies for various automotive drive motors, such as permanent magnet synchronous drive motors, asynchronous drive motors, hub motors, and auxiliary motors. Furthermore, the method described in this invention is based on coordinate measurement and mathematical calculations, and can be integrated with coordinate measuring machines, optical measuring equipment, and automated testing lines. It easily achieves automated, digital, and intelligent online testing, fully meeting the development needs of high-efficiency, high-consistency, and large-scale intelligent manufacturing in new energy vehicles. It is easy to integrate into automated systems and meets the requirements of intelligent and high-efficiency mass production.

[0084] Glossary

[0085] Stator assembly: In this invention, it refers to the core stationary component of the drive motor of a new energy vehicle, which is assembled from the stator core, stator teeth, insulation structure, etc. It is the basic structure for establishing the motor's magnetic field and ensuring power output.

[0086] Stator teeth: In this invention, the protruding tooth-like structure that is uniformly distributed in the circumference of the stator assembly is referred to. Its radial and circumferential micro-sizes directly determine the uniformity and consistency of the air gap between the stator and the rotor.

[0087] Microscopic dimensions: In this invention, the radial displacement deviation, circumferential position deviation, ellipticity, local fluctuation, and other minute dimensional parameters of the specified sub-tooth portion are distinguished from macroscopic geometric dimensions such as roundness and cylindricity.

[0088] A end face / B end face: In this invention, two reference end faces of the stator assembly that are opposite each other along the axial direction are used to realize the synchronous detection and comparative analysis of the micro-dimensions of the stator teeth on both end faces.

[0089] Measurement plane: In this invention, it refers to the cross-section 5mm axially inside the A end face and the B end face, respectively, used to avoid end face chamfers, burrs and local deformation areas, so as to ensure the authenticity and accuracy of tooth size measurement.

[0090] Feature point: In this invention, it refers to the coordinate point determined according to rules on the measurement plane. Each stator tooth corresponds to two feature points, which are used to characterize the spatial position of the tooth and obtain coordinate data.

[0091] Spatial displacement sequence In this invention, the difference between the actual distance from the feature point to the geometric center of the stator and the inner diameter R of the standard stator tooth is used to quantify the actual deviation of the micro-size of the stator tooth.

[0092] Spatial angle sequence In this invention, the angular position of the feature point in the stator circumferential direction is calculated according to Di=180×i / Z, providing an angular reference for the Fourier analysis of the micro-dimensions of the stator teeth.

[0093] Fourier component amplitude In this invention, the term refers to the amplitude values ​​of each component obtained by decomposing the micro-dimensional fluctuations of the stator teeth after Fourier transform and weighting with the Hanning window function. Let be the order of Fourier analysis.

[0094] Second-order component: In this invention, it refers to the Fourier order. The component with a value of 2 corresponds to the elliptic deformation of the inner circle of the stator, and is a key component affecting air gap uniformity, electromagnetic noise, and assembly quality.

[0095] Higher-order components: In this invention, these refer to the Fourier order. The components of 3 to 10 correspond to the minute dimensional fluctuations in the teeth caused by processes such as lamination, core stacking, and welding.

[0096] Second-order variance coefficient In this invention, the term refers to the quantification value of the dispersion of the second-order Fourier component amplitudes of multiple sets of sample stators, which is used to reflect the consistency level of the second-order dimensional fluctuations of stators in the same batch.

[0097] Higher-order variance coefficients In this invention, the term refers to the quantification value of the dispersion of the higher-order Fourier component amplitudes of multiple sets of sample stators, which is used to reflect the consistency level of the higher-order dimensional fluctuations of stators in the same batch.

[0098] Second-order component stability coefficient In this invention, the quantization coefficient, which is obtained by combining the second-order variance coefficient and the maximum second-order amplitude, is used to assess the risk level caused by the second-order dimensional deformation of the stator.

[0099] Higher-order component stability coefficient In this invention, the quantization coefficient obtained by combining the higher-order variance coefficient and the maximum value of the higher-order amplitude is used to assess the risk level caused by local dimensional fluctuations in the stator teeth.

[0100] Comprehensive evaluation coefficient In this invention, the term refers to a unique quantitative index that integrates the second-order component stability coefficient, the higher-order component stability coefficient, the two end face deviations, and the stator tooth inner diameter R, used for stator micro-dimensional risk rating.

[0101] Hanning window function: In this invention, it refers to the function in the formula. The weighting term is used to suppress spectral leakage during Fourier analysis and improve the accuracy of size decomposition and calculation.

[0102] Sample size N: In this invention, it refers to the number of stator assemblies used for batch statistical analysis. This invention requires a sample size N ≥ 10 to ensure the statistical validity and engineering representativeness of the evaluation results.

[0103] Stator tooth count Z: In this invention, it refers to the total number of teeth distributed circumferentially within the stator assembly. It is a fundamental structural parameter for feature point selection, spatial angle calculation, and Fourier analysis.

[0104] Stator tooth inner diameter R: In this invention, the theoretical standard inner circle radius of the stator tooth is specified and used for the normalization of spatial displacement sequence calculation and comprehensive evaluation coefficient.

[0105] Risk rating: In this invention, it refers to the rating based on a comprehensive evaluation coefficient. The five-level risk system, namely, risk out of control, risky, risky, good, and excellent, is used to intuitively determine the quality level of stator dimensions.

[0106] Rotor rubbing: In this invention, it refers to the failure phenomenon in which the rotor and stator teeth directly contact and rub against each other during motor operation, which is usually caused by excessive micro-dimensional deviation of the stator teeth.

[0107] Heat fitting delamination: In this invention, after the sub-assembly and the motor housing are assembled using a heat fitting process, assembly defects such as loose fit and excessive gaps appear on the mating surfaces. Attached Figure Description

[0108] Figure 1 This is a flowchart illustrating the microscopic dimensional analysis and evaluation method for the stator assembly of the vehicle drive motor of the present invention.

[0109] Figure 2 This is a schematic diagram of the end face of the stator assembly of the vehicle drive motor of the present invention;

[0110] Figure 3This is a schematic diagram of the planar feature point identification and coordinate acquisition of the A end face of the stator assembly of the vehicle drive motor according to the present invention;

[0111] Figure 4 This is a schematic diagram of the Fourier analysis calculation results of the measurement plane of end face A of sample No. 1 stator assembly in this embodiment of the invention;

[0112] Figure 5 This is a schematic diagram of the Fourier analysis calculation results of the measurement plane of the B end face of the stator assembly of sample No. 1 in this embodiment of the invention. Detailed Implementation

[0113] like Figures 1 to 3 As shown, a method for microscopic dimensional analysis and evaluation of a vehicle drive motor stator assembly includes the following steps:

[0114] 1) Microscopic dimensional measurement of stator tooth space

[0115] No fewer than 10 automotive drive motor stator assemblies were selected as test samples. The two opposite end faces of the stator assembly along the axial direction were defined as end face A and end face B, respectively. In the axial direction, the cross-sections at 5mm axially inner side of end face A and end face B were used as measurement planes. The 5mm axially inner side refers to the cross-sectional position formed by offsetting 5mm from the corresponding end face into the stator along the stator axis.

[0116] On the two measurement planes mentioned above, the spatial micro-dimensions of each stator tooth are detected, and the coordinate data of two feature points corresponding to each stator tooth are obtained. The specific detection method is as follows: a stator tooth is randomly selected in the measurement plane, and the center point of the tooth is used as the positioning reference. With the geometric center of the stator as the center and the distance from the geometric center to the center point of the tooth as the radius, arcs with an angle of 180° / Z (Z is the number of stator teeth in the stator assembly) are drawn along the positive and negative directions respectively. The coordinates of the two endpoints of the arcs are recorded, which are the coordinate data of the two feature points of the stator tooth. The coordinate data of the two feature points of all stator teeth are obtained in the same way.

[0117] 2) Fourier analysis of the spatial micro-dimensions of the stator teeth

[0118] Based on the coordinate data of each feature point measured in step 1), Fourier transform analysis is performed on the micro-size of the stator tooth space on the measurement planes of the A end face and B end face of the stator assembly, and the amplitude of each order of Fourier component of the micro-size of the stator tooth space on the measurement planes of the A end face and B end face is calculated.

[0119] Fourier transform analysis was performed on all tested samples to obtain the microscopic dimensions of the tooth space for each sample on the A-end face and B-end face measurement planes. The magnitude of the Fourier component is denoted as: , .

[0120] 2-1) Measurement plane of end face A Fourier component amplitude

[0121] ;

[0122] ;

[0123] ;

[0124] In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space on end face A of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the A end face of the stator assembly. The number of stator teeth. For the measurement plane of end face A of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face A of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face A, the first Feature points axis coordinate values, For measuring the plane of end face A, the first Feature points axis coordinate values, This refers to the inner diameter of the stator teeth.

[0125] 2-2) Measurement plane of end face B Fourier component amplitude

[0126] ;

[0127] ;

[0128] ;

[0129] In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space at end face B of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the B end face of the stator assembly. The number of stator teeth. For the measurement plane of end face B of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face B of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face B Feature points axis coordinate values, For measuring the plane of end face B Feature points axis coordinate values, This refers to the inner diameter of the stator teeth.

[0130] 3) Calculation of comprehensive evaluation coefficient for micro-dimensional structure of stator assembly

[0131] Based on the amplitudes of the Fourier components of the measurement planes at end A and end B obtained in step 2), the second-order component stability coefficient and the higher-order component stability coefficient of the micro-dimensional dimensions of the stator teeth are calculated respectively, and finally the comprehensive evaluation coefficient of the micro-dimensional dimensions of the stator assembly is obtained.

[0132] 3-1) Calculate the second-order component stability coefficient of the microscopic dimensions of the tooth space on the A-end face and B-end face of the stator assembly.

[0133] + ;

[0134] + ;

[0135] ;

[0136] ;

[0137] In the formula, The number of stator assembly samples. For all samples, measure the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions at the A end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the A-end face of the stator assembly for all samples. This is the sample number of the stator assembly. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the second-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions was measured at the B end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the B end face of the stator assembly for all samples. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section is measured at the B end face of the stator assembly for all samples.

[0138] 3-2) Calculate the higher-order component stability coefficients of the microscopic dimensions of the tooth space on the A and B end faces of the stator assembly.

[0139] + ;

[0140] + ;

[0141] ;

[0142] ;

[0143] In the formula, For higher-order Fourier series from 3 to 10, The number of stator assembly samples. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at end face A of the stator assembly. For all samples, measure the higher-order variance coefficients of the planar tooth space micro-dimensions on the A end face of the stator assembly. This is the sample number of the stator assembly. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at the B end face of the stator assembly. The higher-order variance coefficients of the planar tooth space micro-dimensions were measured for the stator assembly B end face for all samples. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

[0144] 3-3) Calculate the comprehensive evaluation coefficient of the micro-size of the stator assembly.

[0145] ;

[0146] In the formula, DWZ is the comprehensive evaluation coefficient of the micro-size of the stator assembly, MAX is the function for maximizing the value, and MIN is the function for minimizing the value. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly A end face tooth section for all samples. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples. The order of the higher-order Fourier components of the microscopic dimensions of the teeth on the A and B end faces of the stator assembly is given. For all samples, the higher-order component stability coefficients of the micro-dimensional space of the stator assembly A end face tooth section are given. R is the higher-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples, and R is the inner diameter of the stator tooth.

[0147] 4) Microscopic analysis and evaluation of drive motor stator assembly

[0148] Based on the comprehensive evaluation coefficient of the stator assembly micro-size obtained in step 3), the score and risk rating results of the automotive drive motor stator assembly micro-size are obtained according to the preset theoretical grading standard.

[0149] The theoretical grading standard (out of 5 points) includes:

[0150] DWZ≥2.8, score 1, micro-scale risk out of control;

[0151] 2.0≤DWZ<2.8, score 2 points, indicating a high risk in micro-scale dimensions;

[0152] 1.6≤DWZ<2.0, score 3, there is a risk in micro-scale analysis;

[0153] 1.2≤DWZ<1.6, score 4, good microstructure;

[0154] DWZ < 1.2, rating 5 points, excellent micro-size.

[0155] It is worth noting that the 5-point grading system established in this invention has achieved a comprehensive evaluation of the stator assembly's dimensional performance, ranging from microscopic risk out of control to microscopic excellence. In fact, under the same risk level, this invention can further subdivide into different scoring grades to achieve a refined judgment of the stator assembly's microscopic dimensions. This facilitates accurate differentiation of the dimensional stability levels of different products when summarizing and statistically analyzing large-scale data from multiple projects. Furthermore, the scoring system of this invention has flexible scalability. It can be further subdivided into grades based on actual evaluation accuracy requirements, refining the existing levels into more sub-grades, such as adjusting to a 10-point system or other higher-granularity scoring format, to adapt to the differentiated evaluation accuracy needs of different R&D stages and quality control scenarios.

[0156] The following is an example using the micro-dimensional analysis and evaluation methods for automotive drive motor stator assemblies described above:

[0157] This embodiment adopts a commonly used stator structure in mass production, with the number of stator teeth Z set to 48 and the inner diameter R of the stator teeth set to 50mm. To ensure the statistical results have engineering validity and measurement repeatability, 10 stator assemblies were selected as the analysis sample, with sample numbers numbered 1 to 10. Each stator tooth corresponds to two measurement feature points, and the total number of feature points on a single end face is twice the number of stator teeth, i.e., 2Z. Simultaneously, the Fourier analysis order used in this invention covers orders 1 to 10, with order 2 being the second-order component of primary interest, and orders 3 to 10 uniformly treated as higher-order components for calculation and evaluation. The specific micro-dimensional analysis and evaluation method for automotive drive motor stator assemblies includes the following steps:

[0158] 1) Measurement of the micro-dimensions of the stator teeth

[0159] First, coordinate data of key positions of the stator teeth are obtained through a standardized sampling method, providing original coordinate data of all feature points for subsequent microscopic dimensional analysis.

[0160] The two opposite end faces of the stator assembly along the axial direction are defined as end face A and end face B, respectively. In order to avoid end face chamfers, burrs and local deformation areas caused by processing or assembly, and to ensure that the measurement results can truly reflect the dimensional state of the stator body, the cross-sections 5mm inside the axial direction of end face A and end face B are used as the measurement planes.

[0161] Taking the measurement plane at end A as an example, first randomly select a tooth as the first measurement tooth. Using the geometric center point of this tooth as the positioning reference, and the overall geometric center of the stator as the center, and the distance from the center of the stator to the center point of this tooth as the radius, draw arcs by rotating 180° / Z in both the positive and negative directions. The two endpoints of these arcs are taken as feature points of the current tooth, and their Cartesian coordinates on the plane are recorded as follows: , .

[0162] Following the same point-sampling rules, angle requirements, and positioning methods, feature points were sequentially collected for the second to the Zth teeth, ultimately yielding the coordinates of all 2Z feature points on the A-end face measurement plane, denoted as follows: , ,...., Complete the acquisition of feature points of all teeth on end face A of the stator assembly.

[0163] The coordinates of all feature points on the A-5mm end face of sample No. 1 in this embodiment are shown in Table 1:

[0164] Table 1

[0165]

[0166]

[0167]

[0168] Using the same measurement method, point acquisition sequence, and coordinate definition as end face A, feature point acquisition of the measurement plane at end face B was completed, obtaining the coordinates of all 2Z feature points on end face B, which are denoted as follows: , ,...., , .

[0169] The coordinates of all feature points on the B-5mm end face of sample No. 1 in this embodiment are shown in Table 2:

[0170] Table 2

[0171]

[0172] In this embodiment, by performing the above measurement process on 10 sets of stator assembly samples, 10 sets of complete coordinate data of all feature points on the A end face and B end face can be obtained, which can be used as the basis data for subsequent Fourier analysis.

[0173] 2) Fourier analysis of the microscopic dimensions of the stator teeth space

[0174] Based on the coordinate data of all feature points of the 10 complete sets of measurement planes on end A and end B obtained in step 1), the spatial displacement sequence and corresponding spatial angle of each feature point are first calculated. Then, through Fourier transform, the continuous size distribution is decomposed into component amplitudes of different orders to achieve quantitative analysis of micro-size fluctuations. The specific steps are as follows:

[0175] 2-1) Calculate the spatial displacement sequence

[0176] In this embodiment, the spatial displacement sequence is used to characterize the actual distance from each feature point to the stator center and the magnitude of the deviation from the standard stator tooth inner diameter. The sequence is used to measure the first [number] feature point in the plane between end faces A and B. For each feature point, calculate its spatial displacement sequence using the following formula:

[0177] ;

[0178] ;

[0179] In the formula, The serial numbers of the feature points within the measurement planes on end faces A and B of the stator assembly are given, with values ​​ranging from 1 to 2Z. For the measurement plane of end face A of stator assembly Spatial displacement sequence of feature points For measuring the plane of end face A, the first Feature points axis coordinate values, For measuring the plane of end face A, the first Feature points axis coordinate values, The inner diameter of the stator teeth. For the measurement plane of end face B of stator assembly Spatial displacement sequence of feature points For the measurement plane of end face B of stator assembly Spatial angles corresponding to a sequence of spatial displacements For measuring the plane of end face B Feature points axis coordinate values, For measuring the plane of end face B Feature points Axis coordinate values.

[0180] 2-2) Calculate the spatial angles corresponding to the spatial displacement sequence.

[0181] After obtaining 10 complete spatial displacement sequences of all feature points on the A-end and B-end measurement planes, the spatial angle corresponding to each feature point is calculated. This spatial angle is used to determine the position of the feature point in the circumferential direction, providing an angular basis for the Fourier transform.

[0182] The first plane in the measurement plane of end face A and end face B For each feature point, calculate the spatial angle corresponding to the spatial displacement sequence of that feature point using the following formula:

[0183] ;

[0184] ;

[0185] In the formula, The serial numbers are the feature points within the measurement plane of the A end face of the stator assembly. The number of stator teeth. For the measurement plane of end face A of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For the measurement plane of end face B of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point.

[0186] In this embodiment, the spatial sequence and spatial angles calculated from end faces A and B of sample 1 are shown in Table 3:

[0187] Table 3

[0188]

[0189] 2-3) Calculate the amplitude of each Fourier component.

[0190] To avoid spectral leakage during Fourier analysis and effectively improve the accuracy of size decomposition, the spatial displacement sequences of each feature point in the measurement planes of end faces A and B obtained in step 2-1), and the corresponding spatial angles of the spatial displacement sequences of each feature point in the measurement planes of end faces A and B obtained in step 2-2), are weighted using a Hanning window function before Fourier transform is performed. This yields the final micro-dimensions of the teeth on the A and B end faces of the stator assembly. The magnitude of the first component is calculated using the following formula:

[0191] In the formula, The Fourier order is denoted by 1, and its value ranges from 1 to 10. Measuring the microscopic dimensions of the planar tooth space on end face A of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the A end face of the stator assembly. The number of stator teeth. For the measurement plane of end face A of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face A of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. Measuring the microscopic dimensions of the planar tooth space at end face B of the stator assembly Fourier component amplitude, For the measurement plane of end face B of stator assembly Spatial displacement sequence of feature points For the measurement plane of end face B of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point.

[0192] Among them, when When =1, it represents the magnitude of the first-order Fourier component. When = 2, it represents the magnitude of the second-order Fourier component. When the value is 3 to 10, it represents the amplitude of the higher-order Fourier components from the 3rd to the 10th order (the calculation results of the amplitudes of each order of Fourier components on the A and B ends of sample 1 in this embodiment are as follows). Figures 4-5 (As shown).

[0193] The above calculations were performed sequentially on 10 sets of samples to obtain the amplitudes of the 1st to 10th Fourier components at both ends A and B of the 10 sets of samples, denoted as: , ,....., , These amplitude results will be used to calculate the stability coefficients of the second-order and higher-order components, respectively.

[0194] In this embodiment, the calculated Fourier results for sample 1 are as follows: Figure 3 As shown.

[0195] 3) Calculate the comprehensive evaluation coefficient of the micro-size of the stator assembly.

[0196] Based on the amplitudes of the Fourier components of the micro-dimensional space of the teeth on the A and B end faces of the stator assembly obtained in step 2), the second-order component stability coefficient and the higher-order component stability coefficient of the A and B end face measurement planes are calculated in sequence. Then, combined with the second-order component stability coefficient and the higher-order component stability coefficient of the two end faces, the comprehensive evaluation coefficient of the micro-dimensional space of the stator assembly is calculated.

[0197] 3-1) Calculation of the stability coefficient of the second-order component at the microscale

[0198] As is well known, the second-order component is a key component affecting stator roundness and air gap uniformity. In this embodiment, based on the amplitudes of the second-order Fourier components of the micro-dimensional space of the teeth on end faces A and B obtained in steps 2-3), the dispersion between samples is first calculated, and then the dispersion and the maximum deviation are combined to obtain the second-order component stability coefficient, which is used to quantitatively evaluate the risk level of second-order dimensional fluctuations. The specific steps are as follows:

[0199] In this embodiment, the variance coefficient can be used to reflect the dispersion of the second Fourier amplitudes of the 10 sets of samples. The greater the dispersion, the worse the dimensional consistency. Specifically, the second variance coefficients of the spatial micro-dimensions of the stator assembly's A-end and B-end measuring plane teeth of the 10 sets of samples are calculated according to the following formula:

[0200] ;

[0201] ;

[0202] In the formula, The number of stator assembly samples. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the A-end face of the stator assembly for all samples. This is the sample number of the stator assembly. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face A of the stator assembly of a sample. The arithmetic mean of the second-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is obtained. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the B end face of the stator assembly for all samples. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face B of the stator assembly of a sample. The arithmetic mean of the second-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

[0203] In this embodiment, =0.0003926; =0.0002097. =0.039; =0.057.

[0204] After obtaining the second-order variance coefficients of the microscopic dimensions of the tooth space on the A and B end faces of the stator assembly in 10 sets of samples, and combining them with the maximum value of the second-order amplitude of the microscopic dimensions of the tooth space on the A and B end faces of the stator assembly in the 10 sets of samples, the second-order component stability coefficient of the microscopic dimensions of the tooth space on the A and B end faces of the stator assembly in the 10 sets of samples is obtained. This coefficient reflects both the dispersion of dimensional fluctuations and extreme deviation values. The second-order component stability coefficient of the measurement plane on the A and B end faces of the stator assembly in the 10 sets of samples is calculated according to the following formula:

[0205] + ;

[0206] + ;

[0207] In the formula, For all samples, measure the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions at the A end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the A-end face of the stator assembly for all samples. This is the sample number of the stator assembly. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. For all samples, the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions was measured at the B end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the B end face of the stator assembly for all samples. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face B of the stator assembly of a sample. The maximum value of the second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at the B end face of the stator assembly for all samples.

[0208] In this embodiment, =0.108, =0.102.

[0209] 3-2) Calculation of stability coefficients for higher-order components at the microscale

[0210] As is well known, higher-order components reflect localized minute dimensional fluctuations in the stator teeth and are important factors affecting electromagnetic noise and local stress. In this embodiment, higher-order components refer to components with Fourier orders of 3 to 10. Based on the amplitudes of the higher-order Fourier components of the microscopic dimensions of the teeth on end faces A and B obtained in steps 2-3), the dispersion between samples is first calculated, and then the dispersion and maximum deviation are combined to calculate the stability coefficient of the higher-order components. This coefficient is used to quantitatively evaluate the fluctuation amplitude and consistency of the microscopic dimensional errors of the stator teeth from order 3 to 10, reflecting the influence of local dimensional deviations on the electromagnetic noise, air gap uniformity, and operational stability of the motor. The specific steps are as follows:

[0211] In this embodiment, the higher-order variance coefficients can be used to characterize the dispersion of the higher-order Fourier amplitudes of the 10 sets of samples. Specifically, the higher-order variance coefficients of the microscopic dimensions of the tooth space on the A and B end faces of the stator assembly for the 10 sets of samples are calculated according to the following formula:

[0212] ;

[0213] ;

[0214] In the formula, For higher-order Fourier series from 3 to 10, The number of stator assembly samples. For all samples, measure the higher-order variance coefficients of the planar tooth space micro-dimensions on the A end face of the stator assembly. This is the sample number of the stator assembly. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly of a sample. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. The higher-order variance coefficients of the planar tooth space micro-dimensions were measured for the stator assembly B end face for all samples. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face B of the stator assembly of a sample. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

[0215] Subsequently, the stability coefficients of higher-order components were calculated, and the degree of dispersion and extreme amplitude were considered together to achieve a quantitative assessment of higher-order dimensional risks. Specifically, the stability coefficients of the higher-order components of the spatial micro-dimensions of the planar teeth on the A and B end faces of the stator assemblies of 10 sets of samples were calculated according to the following formula:

[0216] + ;

[0217] + ;

[0218] In the formula, For higher-order Fourier series from 3 to 10, For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at end face A of the stator assembly. For all samples, measure the higher-order variance coefficients of the planar tooth space micro-dimensions on the A end face of the stator assembly. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at the B end face of the stator assembly. The higher-order variance coefficients of the planar tooth space micro-dimensions were measured for the stator assembly B end face for all samples. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

[0219] In this example, =0.00004549; =0.00002849; =0.024; =0.029; =0.078; =0.066.

[0220] 3-3) Calculate the comprehensive evaluation coefficient

[0221] The comprehensive evaluation coefficient in this embodiment integrates second-order dimensional risk, higher-order dimensional risk, and inconsistency risk of both end faces, and is normalized by the stator inner diameter to eliminate numerical differences caused by stators of different specifications, thus possessing cross-model universality.

[0222] Based on the second-order component stability coefficients of the A-end and B-end measurement planes of the 10 sets of samples obtained in step 3-1), and the higher-order component stability coefficients of the A-end and B-end measurement planes of the 10 sets of samples obtained in step 3-2), the comprehensive evaluation coefficient of the micro-size of the stator assembly is calculated according to the following formula:

[0223] ;

[0224] In the formula, DWZ is the comprehensive evaluation coefficient of the micro-size of the stator assembly, MAX is the function for maximizing the value, and MIN is the function for minimizing the value. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly A end face tooth section for all samples. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples. The order of the higher-order Fourier components of the microscopic dimensions of the teeth on the A and B end faces of the stator assembly is given. For all samples, the higher-order component stability coefficients of the micro-dimensional space of the stator assembly A end face tooth section are given. R is the higher-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples, and R is the inner diameter of the stator tooth.

[0225] in, The larger value of the second-order stability coefficient for both end faces represents the maximum second-order risk; The larger value of the higher-order stability coefficients at both ends represents the maximum risk of higher-order components; these two items reflect the degree of inconsistency between the second-order and higher-order components at both ends, respectively.

[0226] 4) Microscopic size scoring and risk rating

[0227] Based on the comprehensive evaluation coefficient of the stator assembly micro-sizes obtained in step 3), a score is assigned and the micro-size risk level is determined according to a preset theoretical grading standard. The specific grading standard includes:

[0228] DWZ≥2.8, score 1, micro-dimensional risk out of control, core motor noise deterioration >10dB, risk of delamination failure after thermal assembly of stator assembly and motor housing is completely out of control, probability of stator rubbing failure during motor operation is extremely high, this batch of stator assemblies must not enter the subsequent assembly process and should be scrapped directly; at the same time, a completely new design and development of the overall structure of the motor stator assembly is required.

[0229] 2.0≤DWZ<2.8, score 2 points, micro-dimensional risk is relatively high, 6dB<deterioration of core motor noise≤10dB, there is an extremely high risk of delamination failure after thermal assembly of stator assembly and motor housing. This batch of stator assembly is suspended from subsequent assembly processes. There is no need to redesign the motor structure. Instead, a comprehensive evaluation and systematic optimization of the entire manufacturing process and core structural parameters of the motor stator assembly is required. The optimization objects include, but are not limited to, stator outer diameter, stator cooling oil circuit structure, stator slot size, and stator tooth tip structure.

[0230] 1.6≤DWZ<2.0, score 3 points, micro-dimensional risks exist, 3dB<deterioration of core motor noise≤6dB, there is a risk of deformation and delamination failure after thermal assembly of stator assembly and motor housing, this batch of stator assembly needs to be re-inspected and confirmed, and local micro-optimization of stator assembly manufacturing process should be carried out at the same time, including but not limited to stator outer diameter tolerance, cooling oil circuit chamfer structure, stator slot chamfer structure, stator tooth chamfer structure;

[0231] 1.2≤DWZ<1.6, score 4, good micro-dimensions, 1dB<deterioration of core motor noise≤3dB, no significant deformation or delamination failure risk after thermal assembly of stator assembly and motor housing. If the motor NVH performance test results meet the design limit requirements, this batch of stator assemblies can directly enter the subsequent assembly process; if the motor NVH performance test results do not meet the design limit requirements, targeted optimization and adjustment of stator outer diameter, stator cooling oil circuit structure, stator slot size, and stator tooth tip structure size are required.

[0232] DWZ < 1.2, rated 5 points, excellent micro-size, core motor noise degradation ≤ 1dB, no stator assembly thermal assembly delamination, motor running rubbing and other related dimensional risks, this batch of stator assemblies can be given priority for subsequent assembly processes.

[0233] Based on the above measurements and calculations, the comprehensive evaluation coefficient DWZ = 1.33, corresponding to a rating of 4 points. The micro-dimensional condition is good, and the noise degradation of the core motor is less than 3dB, which meets the assembly and usage requirements.

[0234] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for microscopic dimensional analysis and evaluation of a stator assembly for an automotive drive motor, characterized in that, Includes the following steps: 1) At both ends of the axial direction of each vehicle drive motor stator assembly, the micro-dimensions of the stator tooth space are detected to obtain the coordinate data of two feature points for each tooth; 2) Based on the coordinate data obtained in step 1), Fourier analysis is performed on the micro-dimensions of the stator tooth space to obtain the amplitudes of each order of Fourier components of the micro-dimensions of the tooth space at end face A and end face B of the stator assembly. 3) Based on the amplitudes of each Fourier component obtained in step 2), the comprehensive evaluation coefficients of the micro-size of the stator assembly are obtained; 4) Based on the comprehensive evaluation coefficient obtained in step 3), the micro-dimensional scoring results and risk rating results of the automotive drive motor stator assembly are obtained according to the preset theoretical grading standards.

2. The method for microscopic dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 1, characterized in that, In step 1), the number of samples of the vehicle drive motor stator assembly is ≥10.

3. The method for micro-dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 1, characterized in that, In step 1), when inspecting the micro-dimensional dimensions of the stator teeth, the cross-sections 5mm axially inside the A end face and 5mm axially inside the B end face are used as the measurement planes.

4. The method for microscopic dimension analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 1, characterized in that, In step 1), the detection method for the coordinate data of the two feature points of each tooth is as follows: On the measurement planes of end face A and end face B of the stator assembly, randomly select a tooth, take the center point of the tooth as the positioning reference, take the geometric center of the stator as the center, and take the distance from the geometric center of the stator to the center point of the tooth as the radius, draw 180° / Z degree arcs in the positive and negative directions respectively, and obtain the coordinates of the two arc endpoints, which are the coordinate data of the two feature points of the tooth.

5. The method for microscopic dimension analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 1, characterized in that, In step 2), the amplitudes of each order of Fourier components of the micro-dimensional space of the teeth on end faces A and B of the stator assembly are calculated according to the following formulas: 2-1) Measurement plane at end A ； ； ； In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space on end face A of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the A end face of the stator assembly. The number of stator teeth. For the measurement plane of end face A of stator assembly Spatial displacement sequence of feature points It is a natural constant. For the measurement plane of end face A of stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face A, the first Feature points axis coordinate values, For measuring the plane of end face A, the first Feature points axis coordinate values, This refers to the inner diameter of the stator teeth. 2-2) Measurement plane of end face B ； ； ； In the formula, It is the Fourier order. Measuring the microscopic dimensions of the planar tooth space at end face B of the stator assembly Fourier component amplitude, The serial numbers are the feature points within the measurement plane of the B end face of the stator assembly. The number of stator teeth. For measuring the plane of end face B of the stator assembly Spatial displacement sequence of feature points It is a natural constant. For measuring the plane of end face B of the stator assembly The spatial angles corresponding to the spatial displacement sequence of each feature point. For measuring the plane of end face B Feature points axis coordinate values, For measuring the plane of end face B Feature points axis coordinate values, This refers to the inner diameter of the stator teeth.

6. The method for micro-dimensional analysis and evaluation of automotive drive motor stator assembly according to claim 1, characterized in that, In step 3), the comprehensive evaluation coefficient of the micro-size of the stator assembly is obtained as follows: 3-1) Based on the amplitudes of each Fourier component obtained in step 2), calculate the second-order component stability coefficients of the spatial micro-dimensions of the toothed parts on the A-end face and B-end face of the stator assembly, respectively. 3-2) Based on the amplitudes of each Fourier component obtained in step 2), calculate the stability coefficients of the higher-order components of the micro-dimensional space of the tooth section on the A-end face and B-end face of the stator assembly, respectively. 3-3) Based on the second-order component stability coefficient obtained in step 3-1) and the higher-order component stability coefficient obtained in step 3), the comprehensive evaluation coefficient of the micro-size of the stator assembly is calculated.

7. The method for microscopic dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 6, characterized in that, In step 3-1), the second-order component stability coefficients of the spatial micro-dimensions of the planar teeth on end faces A and B of the stator assembly are calculated according to the following formula: + ； + ； ； ； In the formula, The number of stator assembly samples. For all samples, measure the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions at the A end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the A-end face of the stator assembly for all samples. This is the sample number of the stator assembly. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section on end face A of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the A end face of the stator assembly. The average value of the second-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, the second-order component stability coefficient of the planar tooth space micro-dimensional dimensions was measured at the B end face of the stator assembly. The second-order variance coefficients of the planar tooth spatial micro-dimensions were measured on the B end face of the stator assembly for all samples. For the first The second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the second-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the B end face of the stator assembly. The average value of the second-order Fourier component amplitude of the spatial micro-dimensional dimensions of the planar tooth section is measured at the B end face of the stator assembly for all samples.

8. The method for microscopic dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 6, characterized in that, In step 3-2), the higher-order component stability coefficients of the spatial micro-dimensions of the planar teeth on end faces A and B of the stator assembly are calculated according to the following formula: + ； + ； ； ； In the formula, For higher-order Fourier series from 3 to 10, The number of stator assembly samples. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at end face A of the stator assembly. For all samples, measure the higher-order variance coefficients of the planar tooth space micro-dimensions on the A end face of the stator assembly. This is the sample number of the stator assembly. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth spatial micro-dimensional dimensions at the A end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face A of the stator assembly for all samples is calculated. For all samples, measure the higher-order component stability coefficients of the planar tooth spatial micro-dimensions at the B end face of the stator assembly. The higher-order variance coefficients of the planar tooth space micro-dimensions were measured for the stator assembly B end face for all samples. For the first The higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar tooth section at end face B of the stator assembly of a sample. For all samples, measure the maximum value of the higher-order Fourier component amplitude of the planar tooth space micro-dimensional dimensions at the B end face of the stator assembly. The average value of the higher-order Fourier component amplitudes of the spatial micro-dimensions of the planar teeth at the B end face of the stator assembly for all samples.

9. The method for microscopic dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 6, characterized in that, In step 3-3), the comprehensive evaluation coefficient of the micro-dimensional structure of the stator assembly is calculated according to the following formula: ； In the formula, DWZ is the comprehensive evaluation coefficient of the micro-size of the stator assembly, MAX is the function for maximizing the value, and MIN is the function for minimizing the value. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly A end face tooth section for all samples. Let be the second-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples. The order of the higher-order Fourier components of the microscopic dimensions of the teeth on the A and B end faces of the stator assembly is given. For all samples, the higher-order component stability coefficients of the micro-dimensional space of the stator assembly A end face tooth section are given. R is the higher-order component stability coefficient of the micro-dimensional space of the stator assembly B end face tooth section for all samples, and R is the inner diameter of the stator tooth.

10. The method for micro-dimensional analysis and evaluation of the stator assembly of a vehicle drive motor according to claim 1, characterized in that, In step 4), the theoretical grading criteria include: DWZ≥2.8, score 1, micro-scale risk out of control; 2.0≤DWZ<2.8, score 2 points, indicating a high risk in micro-scale dimensions; 1.6≤DWZ<2.0, score 3, there is a risk in micro-scale analysis; 1.2≤DWZ<1.6, score 4, good microstructure; DWZ < 1.2, rating 5 points, excellent micro-size.

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