A method for optimizing the whine of a coaxial electric drive axle reducer

Abstract

The present invention relates to the technical field of electric drive assembly design, and specifically discloses an optimization method for the whine of a coaxial electric drive axle reducer, including obtaining the number of teeth and pairing information of the reducer gears, as well as the number of motor pole pairs and the number of motor slots information; based on the number of teeth and pairing information of the reducer gears, obtaining the first main order and the first harmonic order of gear meshing; based on the number of motor pole pairs and the number of motor slots information, obtaining the second main order and the second harmonic order of the motor; according to the first main order and the first harmonic order, and the second main order and the second harmonic order, determining whether the main order and the harmonic order of gear meshing and the motor are coupled; if not coupled, establishing a simulation model of gear transmission error and gear contact patch, outputting a standard parameter set based on the simulation model, comprehensively considering the design related to whine in the design process, avoiding gear whine in advance, and reserving measures in advance at the weak structural links prone to whine problems to avoid high costs for dealing with whine problems in the later stage.

Description

Technical Field

[0001] The present invention relates to the technical field of electric drive assembly design, and more particularly to a method for optimizing the whine of a coaxial electric drive axle reducer. Background Art

[0002] The drive system of new energy vehicles mainly consists of an electric motor and a reducer. Noise is generated during the operation of the electric motor and the reducer, and the noise is mainly whine. Gear whine noise is a steady-state noise excited by a dynamic meshing force. Due to the continuous change of the meshing stiffness during the gear meshing process, the transmission error fluctuates. As a dynamic excitation source, it directly causes the fluctuation of the contact stress of the gear under load. This contact stress fluctuation excites the gear vibration, and the vibration is transmitted to the vehicle interior through components such as the shaft, bearings, reducer housing, mounts, and body to generate whine, or the whine sound generated by the gear is directly transmitted to the vehicle interior through the reducer housing through the air to generate whine.

[0003] The coaxial electric drive axle is a new structural form of axle. The coaxial electric drive axle has unique advantages that the current mainstream offset axles do not have, such as a small radial space, a compact structure, and higher reliability, and has good development prospects.

[0004] In the related art, in order to reduce whine, mainly separate design analysis and optimization processes are carried out for the gears. By analyzing the magnitude of the gear meshing force excitation, the transmission and noise radiation processes of the structure, simulation analysis is carried out from the source excitation to the transmission path. However, this analysis method does not consider the problems encountered in practice, and there is still a difference between theory and practice. For example, whine is not only related to the gears, but may also be related to the structure and stiffness of the housing. There are often situations where the gear optimization has reached its limit, but the whine problem still cannot be solved. Especially for the coaxial electric drive axle, it is necessary to avoid insufficient design consideration, resulting in a large rectification cost or inability to rectify due to electric drive whine in the later stage. Summary of the Invention

[0005] The present invention aims to solve the problem that in the prior art, when the structure of the electric drive system is designed, the whine problem in the coaxial electric drive axle cannot be effectively solved. Therefore, the present invention proposes a method for optimizing the whine of a coaxial electric drive axle reducer.

[0006] To solve the above problems, in a first aspect, the present application provides a method for optimizing the whine of a coaxial electric drive axle reducer, including:

[0007] Obtain the number of teeth and pairing information of the reducer gears, as well as the number of pole pairs and number of slots of the motor;

[0008] Based on the number of teeth and pairing information of the reducer gears, obtain the first main order and the first harmonic order of gear meshing;

[0009] Based on the information of the number of pole pairs and the number of slots of the motor, obtain the second main order and the second harmonic order of the motor;

[0010] According to the first main order and the first harmonic order, and the second main order and the second harmonic order, determine whether the gear meshing and the main order and harmonic order of the motor are coupled;

[0011] If not coupled, establish a simulation model of the gear transmission error and the gear contact patch, and output a standard parameter set based on the simulation model;

[0012] Based on the standard parameter set, process and prepare the corresponding standard gear, install the standard gear on the motor shaft and conduct howling verification and optimization.

[0013] In some possible embodiments, in the step of obtaining the first main order and the first harmonic order of gear meshing based on the number of teeth and the pairing information of the reducer gears, it further includes:

[0014] Based on the number of teeth and the pairing information of the reducer gears, determine whether there is a true common divisor for the paired gear teeth, where the true common divisor is a common divisor other than the value 1.

[0015] In some possible embodiments, the determining whether there is a true common divisor for the paired gear teeth based on the number of teeth and the pairing information of the reducer gears includes:

[0016] If there is the true common divisor, re-design the number of teeth of the paired gears; otherwise, calculate the first main order and the first harmonic order of gear meshing.

[0017] In some possible embodiments, according to the first main order and the first harmonic order, and the second main order and the second harmonic order, determining whether the gear meshing and the main order and harmonic order of the motor are coupled includes:

[0018] Determine whether the first main order of gear meshing is coupled with the second main order and the second harmonic order of the motor; and

[0019] Determine whether the first harmonic order of gear meshing is coupled with the second main order and the second harmonic order of the motor;

[0020] If neither the first main order nor the first harmonic order of gear meshing is coupled with the second main order and the second harmonic order of the motor, the design requirements are met.

[0021] In some possible embodiments, the if neither the first main order nor the first harmonic order of gear meshing is coupled with the second main order and the second harmonic order of the motor, the design requirements are met includes:

[0022] If the absolute value of the numerical difference between the first main order and the second main order, or between the first main order and the second harmonic order, and between the first harmonic order and the second main order, or between the first harmonic order and the second harmonic order is greater than or equal to 1, no coupling occurs; otherwise, coupling occurs.

[0023] In some possible embodiments, if there is no coupling, a simulation model of the gear transmission error and the gear contact patch is established, and a standard parameter set is output based on the simulation model, including:

[0024] Establish a simulation model of the gear transmission error and the gear contact patch;

[0025] Based on the simulation model, set the gear order transmission error and the tolerance range of the gear modification parameters based on the sixth-level precision of the gear to obtain the standard parameter set.

[0026] In some possible embodiments, based on the standard parameter set, a corresponding standard gear is processed and prepared, and the standard gear is installed on the motor shaft and subjected to howling verification and optimization, including:

[0027] Based on the standard parameter set, a worm grinding wheel is used to process the gear. Among them, the number of heads of the grinding wheel used and the number of teeth of the processed gear should not have a common divisor;

[0028] The processed gear is detected for the parameters of the gear tooth profile and tooth direction using a Klingelnberg detector and subjected to three-section inspection of the gear. Among them, the results of the three-section inspection of the gear meet the tolerance range in the standard parameter set.

[0029] In some possible embodiments, based on the standard parameter set, a corresponding standard gear is processed and prepared, and the standard gear is installed on the motor shaft and subjected to howling verification and optimization, and further includes:

[0030] During the installation process, the mating method of the internal spline of the first-stage driving gear of the main reducer and the external spline shaft of the motor is interference fit. The machining precision of the external spline of the motor shaft and the internal spline of the first-stage driving gear of the main reducer is the sixth level, and a first gap is reserved unilaterally between the external spline of the half shaft and the hollow motor shaft.

[0031] In some possible embodiments, based on the standard parameter set, a corresponding standard gear is processed and prepared, and the standard gear is installed on the motor shaft and subjected to howling verification and optimization, and further includes:

[0032] During the howling verification process, different torque values are set to detect the corresponding howling, and the gear modification is re-performed based on the torque value that generates the howling to reduce the transmission error within that torque range.

[0033] In some possible embodiments, during the howling verification process, different torque values are set to detect the corresponding howling, and the gear modification is re-performed based on the torque value that generates the howling to reduce the transmission error within this torque range, including:

[0034] If the gear modification cannot optimize the howling problem, the hollow motor shaft is thickened to optimize the howling.

[0035] Compared with the prior art, the technical solution provided by the present application at least includes the following advantages or beneficial effects:

[0036] 1) For the howling problem of the coaxial electric drive axle, it is proposed to initially optimize by obtaining the first main order and the first harmonic order of gear meshing and the second main order and the second harmonic order of the motor to ensure that there is no common divisor between the number of gear teeth and the number of motor pole pairs, avoiding resonance and coupling problems, ensuring the stability and reliability during system operation, reducing the generation of vibration and noise. Then, a Master simulation model of gear transmission error and gear contact patch is established based on the parameters after the initial optimization. Based on this simulation model, the first version of gear modification parameters is set for the gear order transmission error, and the simulation is carried out according to the tolerance range of the gear modification parameters set according to the gear six-level accuracy, ensuring the high precision and high efficiency of gear transmission and being able to achieve the expected accuracy level in actual manufacturing. According to the data obtained from this theoretical design, specific processing techniques and detection equipment (such as worm grinding wheels and Klingelnberg detectors) are used. Among them, the Klingelnberg detector detects the parameters of gear tooth profile and tooth direction and performs three-section detection of the gear. The detection results of the three sections need to meet the tolerance range output by the simulation model. Then, the processed standard gear and the motor shaft are installed on the vehicle for howling verification and optimization. The method combines simulation with actual processing and production, avoiding the risk of howling occurring later and the situation where the howling problem cannot be solved.

[0037] 2) Since the coaxial electric drive axle is a new type of axle structure with a small radial space, a more compact structure and higher reliability, during the machining and assembly of the standard gear and the motor shaft, the mating method between the internal spline of the first-stage driving gear of the main reducer and the external spline shaft of the motor is an interference fit. The machining accuracy of the external spline of the motor shaft and the internal spline of the first-stage driving gear of the main reducer is grade six. A first clearance is reserved unilaterally between the external spline of the half shaft and the hollow motor shaft. After the vehicle is assembled, different torques are sequentially set and loaded to detect the howling. The gear profile is re-machined for the torque that causes howling to reduce the transmission error within this torque range. In this way, the possible influence of the actual assembly of the hollow motor shaft and the standard gear on the howling problem is fully considered, and the howling is detected by testing different torques, and the gear that generates howling is re-profiled and then tested again to achieve no howling problem in the torque range to be measured. During the design process, the design related to howling is comprehensively considered to avoid gear howling in advance, and measures are reserved in advance at the weak structural links where howling is likely to occur to avoid the howling problem that may occur later, which requires a large cost to solve and may not be solved.

[0038] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 is a flowchart of a method for optimizing the howling of a coaxial electric drive axle reducer according to an embodiment of the present application;

[0041] Figure 2 is another flowchart of a method for optimizing the howling of a coaxial electric drive axle reducer according to an embodiment of the present application; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The embodiments of the present invention will be described in detail below. The embodiments described with reference to the drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0044] The terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, the first end plate and the second end plate are only for distinguishing different end plates and do not limit their sequence. The first end plate can also be named the second end plate, and the second end plate can also be named the first end plate without departing from the scope of the described embodiments. Also, the terms "first", "second", "third", etc. do not necessarily limit the indicated features to be different.

[0045] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, terms such as "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances. The meaning of "a plurality" is at least two, that is, two or more.

[0046] It should be noted that in the present application, words such as "in one embodiment", "exemplarily", "for example", etc. are used to give examples, illustrations or explanations. Any embodiment or design described as "in one embodiment", "exemplarily", "for example" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly, the use of words such as "in one embodiment", "exemplarily", "for example" is intended to present related concepts in a specific manner, meaning that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of the above words at various positions in the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0047] The drive system of new energy vehicles mainly consists of a motor and a reducer. Noise is generated during the operation of the motor and the reducer, and the noise is mainly whistling. Gear whistling noise is a steady-state noise excited by a dynamic meshing force. Due to the continuous change of the meshing stiffness during the gear meshing process, the transmission error fluctuates. As a dynamic excitation source, it directly causes the fluctuation of the contact stress of the gear under load. This contact stress fluctuation excites the gear vibration, and the vibration is transmitted to the vehicle interior through components such as the shaft, bearings, reducer housing, mounts, and vehicle body to generate whistling, or the whistling sound generated by the gear is directly transmitted to the vehicle interior through the reducer housing through the air to generate whistling. Reducer whistling is easily perceived by customers, prone to complaints, and has become one of the noises that urgently need to be optimized in the new energy drive system.

[0048] Currently, the main optimization method for gear whistling in new energy vehicle models is to modify the profile parameters of the gear, and the optimal gear profile parameters are sought through a combination of simulation and testing. Gear whistling belongs to a systematic problem, which is not only related to the gear itself, but more related to its mating boundaries, including the assembly of the gear shaft, bearings, and housing.

[0049] The inventor found that due to its complexity, it is difficult to avoid the gear whistling problem through CAE simulation during the design and development stage. Most of them need to continuously try and error on the vehicle after the product is out and then carry out design optimization to solve the gear whistling problem. Optimizing whistling only through the relevant parameters of the gear itself may be a relatively lucky method because the problem can be solved with less cost. Most of the time, it is rare to achieve the effect of optimizing whistling only through the optimization of gear-related parameters. In reality, the scheme for optimizing whistling is difficult to implement and the cost is huge. For example, whistling is not only related to the gear, but may also be related to the structure and stiffness of the housing. There are often situations where the gear optimization has reached its limit, but the whistling problem still cannot be solved. It may be necessary to optimize the housing. However, once the housing is molded, it is difficult to make subsequent changes, and remolding will cost more, ultimately resulting in a high cost of solving the gear whistling problem or an inability to solve the problem. Therefore, when designing the structure of the electric drive system, it is very necessary to have a system design method that can avoid the gear whistling problem caused by system complexity as much as possible in advance and can avoid the situation where the gear whistling cannot be solved later.

[0050] Based on this, in order to solve the above problems existing in the prior art, the inventor proposes an optimization method for the whistling of a coaxial electric drive axle reducer, which will be specifically described below in conjunction with the embodiments.

[0051] Please refer to Figures 1 to 2 , Figure 1 and Figure 2 which shows a flowchart of an optimization method for the whistling of a coaxial electric drive axle reducer provided by an embodiment of the present application. The method includes:

[0052] Step S100: Obtain the number of teeth and pairing information of the reducer gears, as well as the number of pole pairs and the number of slots of the motor;

[0053] In this step, it should be noted that the reducer and the motor are the main components of the drive system of new energy vehicles and are also the main structural positions where howling occurs. Especially for the reducer gears, due to the continuous change of the meshing stiffness during the gear meshing process, which causes fluctuations in the transmission error, as a dynamic excitation source, it directly leads to fluctuations in the contact stress of the gears under load. This contact stress fluctuation excites the gear vibration, and the vibration is then transmitted to the vehicle interior through components such as the shaft, bearings, reducer housing, mounts, and body to generate howling, or the howling sound generated by the gears is directly transmitted to the vehicle interior through the reducer housing through the air to generate howling. Therefore, it is necessary to obtain the relevant parameters of the reducer gears and the motor.

[0054] Among them, the number of teeth and pairing information of the reducer gears can be obtained from the product specification sheet. The number of teeth refers to the number of teeth of the gears in the reducer, which affects the reduction ratio and transmission efficiency; the pairing information involves the pairing combinations of different gears to ensure the matching performance and transmission efficiency of each gear in the transmission system; the number of pole pairs of the motor refers to the number of magnetic poles inside the motor, and the number of pole pairs determines the operating speed and torque characteristics of the motor. The number of slots of the motor is the number of slots on the rotor or stator of the motor, which is used to accommodate the windings, and these parameters affect the mechanical structure and electromagnetic performance of the motor.

[0055] Step S200: Based on the number of teeth and pairing information of the reducer gears, obtain the first main order and the first harmonic order of gear meshing;

[0056] In this step, it should be explained that through the number of teeth and pairing information of the reducer gears obtained in step S100, the first main order and the first harmonic order of gear meshing are obtained. The first main order refers to the gear meshing frequency, that is, the product of the meshing frequency and the rotational speed, which is used to evaluate the vibration characteristics of the system. The first harmonic order is the resonance frequency of the system based on the first main order, which affects the stability and performance of the system.

[0057] It should be noted that in order to further avoid the possibility of howling, based on the number of teeth and pairing information of the reducer gears, it is judged whether there is a true common divisor for the number of teeth of the paired gears. Among them, the true common divisor is a common divisor other than the numerical value 1. If there is such a true common divisor, the number of teeth of the paired gears is redesigned. Otherwise, the first main order and the first harmonic order of gear meshing are calculated again. It can be understood that this process greatly reduces the occurrence of howling problems caused by gear wear.

[0058] Step S300: Based on the number of pole pairs and the number of slots of the motor, obtain the second main order and the second harmonic order of the motor;

[0059] In this step, it should be explained that the number of pole pairs and the number of slots of the motor obtained through step S100 are used to calculate the second main order and the second harmonic order of the motor. Similar to the vibration analysis of gear meshing, the second main order is the electromagnetic vibration frequency of the motor, usually twice the rotation frequency of the motor. The second harmonic order is the system resonance frequency based on the second main order.

[0060] Step S400: Determine whether the gear meshing and the main order and harmonic order of the motor are coupled according to the first main order and the first harmonic order, and the second main order and the second harmonic order;

[0061] In this step, based on the first main order and the first harmonic order of gear meshing obtained in step S200, and the second main order and the second harmonic order of the motor obtained in step S300, it is further determined whether the gear meshing and the main order and harmonic order of the motor are coupled.

[0062] Specifically, coupling refers to the phenomenon that the vibration frequencies or resonance frequencies of two or more systems affect or interact with each other under certain conditions. In this case, if the frequency of the first main order or the first harmonic order of the gear is close to or overlaps with the frequency of the second main order or the second harmonic order of the motor, the coupling phenomenon may occur. For example, if the meshing frequency (the first main order) of the gear is exactly twice the second main order of the motor, or a certain resonance frequency of the gear system is close to the resonance frequency of the motor, it may cause vibration energy transfer or resonance phenomenon, thereby affecting the stability and performance of the system. Therefore, if there is a phenomenon of frequency proximity or overlap, it is necessary to consider whether there will be a coupling effect between them. This coupling effect may increase the vibration of the system or cause instability, and needs to be evaluated and adjusted during the design or operation process.

[0063] In some embodiments, it is necessary to determine whether the first main order of gear meshing is coupled with the second main order and the second harmonic order of the motor; and determine whether the first harmonic order of gear meshing is coupled with the second main order and the second harmonic order of the motor; if the first main order and the first harmonic order of gear meshing are not coupled with the second main order and the second harmonic order of the motor, the design requirements are met.

[0064] Specifically, if the absolute values of the numerical differences between the first main order of gear meshing and the second main order of the motor, the first main order of gear meshing and the second harmonic order of the motor, the first harmonic order of gear meshing and the second main order of the motor, and the first harmonic order of gear meshing and the second harmonic order of the motor are all greater than or equal to 1, no coupling occurs. Otherwise, coupling occurs. And if the gear meshing and the main order and harmonic order of the motor are coupled, it is necessary to redesign the number of teeth of the mating gears.

[0065] It should be noted that motors can also produce whistling noises, and this problem has not been considered in the current existing technologies. That is, the main orders and harmonic orders of the motor meshing with the gear are not comprehensively considered. If the whistling orders of the motor and the gear are coupled, more serious whistling will occur, thus worsening the gear whistling. This step effectively solves this problem by decoupling the orders of the motor and the gear.

[0066] Step S500: If there is no coupling, establish a simulation model of the gear transmission error and the gear contact patch, and output a standard parameter set based on the simulation model;

[0067] In this step, when step S400 determines that there is no coupling between the gear meshing and the main orders and harmonic orders of the motor, then based on multiple parameters of the gear, including parameters such as size and number of teeth, establish a simulation model of the gear transmission error and the gear contact patch. The standard parameter set is the data finally output through simulation based on the simulation model.

[0068] Specifically, for the simulation model of the gear transmission error, use existing modeling software in the market (such as Master simulation) to create the model. Consider the uncertain factors in the gear manufacturing and installation processes during the establishment of the simulation model, such as tooth profile deviation, axial clearance, and tooth number error, etc., to further determine the basic geometric parameters of the gear and the statistical characteristics of the manufacturing errors. Through numerical simulation, simulate the transmission error of the gear during actual operation to obtain key parameters such as the amplitude and frequency spectrum distribution of the error; for the simulation model of the gear contact patch: use existing modeling software in the market (such as Master simulation) to create the model. Consider factors such as gear material, geometry, load, speed, and lubrication conditions during the modeling process, and input to determine the material properties, working conditions, and lubrication state of the gear. Then, through simulation calculation, simulate the formation and distribution of the contact patch on the gear tooth surface to obtain key parameters such as the contact area and contact pressure distribution.

[0069] It should be noted that after creating the simulation model, output a version of gear modification parameters according to the gear order transmission error ≤ 0.3um, and set the tolerance range of the gear modification parameters according to the sixth-level accuracy of the gear. It should be noted that the sixth-level accuracy standard of the gear is mainly used to determine the range of geometric dimensions and shape errors of the gear, and these errors directly affect the operating efficiency, smoothness, and noise level of the gear during transmission. Under the sixth-level accuracy, the actual tooth profile of a gear may deviate from the ideal tooth profile by ±30μm.

[0070] Step S600: Based on the standard parameter set, process and prepare the corresponding standard gear, install the standard gear on the motor shaft and conduct whistling verification and optimization.

[0071] In this step, based on the standard parameter set obtained through step S500,

[0072] When machining gears using a worm grinding wheel, the number of starts of the grinding wheel used and the number of teeth of the machined gear should not have a common divisor. After the machining of the gear is completed, use a Klingelnberg detector to detect the parameters of the gear tooth profile and tooth direction and conduct a three-section inspection of the gear. The inspection results of the three sections need to meet the tolerance range set in step S500.

[0073] In some embodiments, during the loading process, the mating method between the internal spline of the first-stage driving gear of the main reducer and the external spline shaft of the motor is an interference fit. The machining accuracy of the external spline of the motor shaft and the internal spline of the first-stage driving gear of the main reducer is grade six. A first clearance is reserved unilaterally between the external spline of the half shaft and the hollow motor shaft. Specifically, the first clearance reserved unilaterally between the external spline of the half shaft and the hollow motor shaft can be 18mm, 19mm, or 20mm, which can be set according to actual requirements.

[0074] After the gear and the motor are loaded, conduct a howling verification. Re-profile the torque that causes howling to reduce the transmission error within that torque range. Specifically, during the howling verification process, set different torque values to detect the corresponding howling. Re-profile the gear based on the torque value that causes the howling to reduce the transmission error within that torque range, and repeat steps S200 to S500. If the howling problem cannot be optimized according to the above process, thicken the hollow motor shaft to optimize the howling.

[0075] In the above method steps, for the howling problem of the coaxial electric drive axle, it is proposed to initially optimize by obtaining the first main order and the first harmonic order of gear meshing and the second main order and the second harmonic order of the motor, ensuring that there is no common divisor between the number of teeth of the gear and the number of pole pairs of the motor, avoiding resonance and coupling problems, ensuring the stability and reliability during system operation, reducing the generation of vibration and noise. Then, establish a Master simulation model of gear transmission error and gear contact patch based on the initially optimized parameters. Based on this simulation model, set the gear order transmission error to output the first version of gear re-profiling parameters and conduct a simulation according to the tolerance range of the gear re-profiling parameters set according to the gear grade six accuracy, ensuring the high precision and high efficiency of gear transmission and being able to achieve the expected accuracy level in actual manufacturing. According to the data obtained from this theoretical design, based on the use of specific machining processes and detection equipment (such as worm grinding wheels and Klingelnberg detectors), among which, the Klingelnberg detector detects the parameters of the gear tooth profile and tooth direction and conducts a three-section inspection of the gear. The inspection results of the three sections need to meet the tolerance range output by the simulation model. Then, load the machined standard gear and the motor shaft for howling verification and optimization. The method combines simulation with actual machining production, avoiding the risk of howling occurring later and the situation where the howling problem cannot be solved in advance.

[0076] Meanwhile, considering that the coaxial electric drive axle is a new type of axle structure with a small radial space, a more compact structure, and higher reliability, during the machining and assembly of the standard gear and the motor shaft, the mating method between the internal spline of the first-stage driving gear of the main reducer and the external spline shaft of the motor is an interference fit. The machining accuracy of the external spline of the motor shaft and the internal spline of the first-stage driving gear of the main reducer is grade six. A first clearance is reserved unilaterally between the external spline of the half shaft and the hollow motor shaft. After the vehicle is assembled, different torques are sequentially set for loading to detect the whine, and the gear profile is re-shaped for the torque that causes the whine to reduce the transmission error within this torque range. In this way, the possible influence of the actual assembly of the hollow motor shaft and the standard gear on the whine problem is fully considered, and the whine is detected by testing different torques, and the gear that generates the whine is re-shaped and then tested again to achieve no whine problem in the torque range to be measured. During the design process, the design related to the whine is comprehensively considered, the gear whine is avoided in advance, and measures are reserved in advance at the weak structural links where the whine problem is likely to occur, so as to avoid the whine problem that may occur later, which requires a large cost to solve and may not be solved.

[0077] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0078] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Referring to "embodiment" in this article means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0079] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

[0080] Other embodiments of the present application will be readily contemplated by those skilled in the art in view of the specification and practice of the disclosure herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

Claims

1. A method for optimizing the noise of a coaxial electric drive axle reducer, characterized in that: include: Obtain the number of teeth and pairing information of the reducer gear, as well as the number of motor pole pairs and the number of motor slots; Based on the number of teeth and pairing information of the reducer gear, a first main order and a first harmonic order of the gear meshing are obtained, wherein based on the number of teeth and pairing information of the reducer gear, it is determined whether there is a true common divisor of the number of teeth of the paired gears, and the true common divisor is a common divisor other than the value 1; Based on the information of the number of motor pole pairs and the number of motor slots, a second main order and a second harmonic order of the motor are obtained; Determining whether the gear meshing is coupled with the main order and the harmonic order of the motor according to the first main order and the first harmonic order, and the second main order and the second harmonic order; If there is no coupling, a simulation model of the gear transmission error and the gear contact spot is established, and a standard parameter set is output based on the simulation model; Based on the standard parameter set, the corresponding standard gears are processed and prepared, and the standard gears and the motor shafts are assembled and the howling verification and optimization are performed.

2. The method for optimizing the noise of a coaxial electric drive axle reducer according to claim 1, characterized in that: The step of judging whether there is a true common divisor of the number of teeth of the paired gears based on the number of teeth of the reducer gear and the pairing information includes: If the truth common divisor exists, the number of teeth of the mating gear is redesigned; otherwise, the first main order and the first harmonic order of the gear meshing are calculated.

3. The method for optimizing the noise of a coaxial electric drive axle reducer according to claim 1, characterized in that: According to the first main order and the first harmonic order, and the second main order and the second harmonic order, determining whether the gear meshing is coupled with the main order and the harmonic order of the motor includes: Determine whether a first main order of the gear meshing is coupled with a second main order and a second harmonic order of the motor; and Determine whether the first harmonic order of the gear meshing is coupled with the second main order and the second harmonic order of the motor; If the first main order and the first harmonic order of the gear meshing are not coupled with the second main order and the second harmonic order of the motor, the design requirements are met.

4. The method for optimizing the noise of a coaxial electric drive axle reducer according to claim 3, characterized in that: If the first main order and the first harmonic order of the gear meshing are not coupled with the second main order and the second harmonic order of the motor, the design requirements are met, including: If the absolute values ​​of the numerical differences between the first main order and the second main order, between the first main order and the second harmonic order, and between the first harmonic order and the second main order, and between the first harmonic order and the second harmonic order are all greater than or equal to 1, no coupling occurs; otherwise, coupling occurs.

5. The method for optimizing the howling of a coaxial electric drive axle reducer according to claim 1, characterized in that: If there is no coupling, a simulation model of gear transmission error and gear contact spot is established, and a standard parameter set is output based on the simulation model, including: Establish a simulation model of gear transmission error and gear contact spot; Based on the simulation model, the gear order transmission error is set, and the tolerance range of the gear modification parameters is set based on the sixth-level gear accuracy to obtain the standard parameter set.

6. The method for optimizing the noise of a coaxial electric drive axle reducer according to claim 1, characterized in that: The method of processing and preparing corresponding standard gears based on the standard parameter set, assembling the standard gears and the motor shaft and performing howling verification and optimization includes: Based on the standard parameter set, a worm grinding wheel is used to process the gear, wherein the number of heads of the grinding wheel used and the number of teeth of the processed gear cannot have a common divisor; The machined gear is tested for parameters of gear tooth shape and tooth direction using a Klingelnberg tester and three-section gear test is performed, wherein the results of the three-section gear test meet the tolerance range in the standard parameter set.

7. The method for optimizing the howling of a coaxial electric drive axle reducer according to claim 1, characterized in that: The method further includes: processing and preparing corresponding standard gears based on the standard parameter set, assembling the standard gears and the motor shaft and performing noise verification and optimization; During the loading process, the internal spline of the first-stage driving tooth of the main reducer and the external spline shaft of the motor are interference fit, the machining accuracy of the external spline of the motor shaft and the internal spline of the first-stage driving tooth of the main reducer is level six, and the first gap is reserved on one side between the external spline of the half shaft and the hollow motor shaft.

8. The method for optimizing the howling of a coaxial electric drive axle reducer according to claim 1, characterized in that: The method further includes: processing and preparing corresponding standard gears based on the standard parameter set, assembling the standard gears and the motor shaft and performing noise verification and optimization; During the howling verification process, different torque values ​​are set to detect the corresponding howling, and the gear is reshaped based on the torque value that generates the howling to reduce the transmission error within the torque range.

9. The method for optimizing the howling of a coaxial electric drive axle reducer according to claim 8, characterized in that: During the howling verification process, different torque values ​​are set to detect corresponding howling, and the gear is reshaped based on the torque value that generates the howling to reduce the transmission error within the torque range, including: If the gear modification cannot optimize the howling problem, the hollow motor shaft can be thickened to optimize the howling.

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