Method for adjusting squeal of electric drive axle of new energy automobile

Abstract

The invention discloses an adjustment and calibration method for squeal of an electric drive axle of a new energy automobile. The adjustment and calibration method comprises the following steps: S1, calculating and testing squeal orders and problem points of the electric drive axle; s2, real vehicle modal testing of an electric drive axle assembly, a suspension system of the electric drive axle assembly and a cab; s3, analyzing a mode; s4, controlling the vibration isolation rate of each vehicle body suspension system; s5, reducing gear meshing excitation adjustment; s6, establishing a gear transmission error CAE simulation model of each gear pair of the speed reducer; s7, performing CAE simulation and recommending speed reducer gear initial version modification parameters; s8, the gear is subjected to shape correction machining, and a sample piece is manufactured; s9, real vehicle subjective driving evaluation and objective data test verification; s10, determining a design parameter tolerance; s11, correcting a contact spot tolerance; s12, the design is frozen, a technical file is output, and electric drive axle howling adjustment is completed; detailed adjustment is carried out from an excitation source generated by electrically-driven howling to a transmission path and then to response, CAE simulation analysis and actual production and manufacturing are deeply fused, and the system is reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of electric drive axles for new energy vehicles, and specifically to a tuning method for the howling of electric drive axles of new energy vehicles. Background Art

[0002] People's living standards are getting higher and higher, and there is a new understanding of the definition of automobiles. Higher requirements are put forward for the overall vehicle comfort. NVH performance is an important field and the most direct experience for customers. Therefore, it poses a great challenge to the development of NVH for new energy vehicles. The electric drive axle is an important transmission unit of new energy vehicles. In order to match the speed ratio requirements, it is usually designed with gear transmission inside, and usually has one or more pairs of gears. During the driving process of the vehicle, the motor with extremely high speed drives the electric drive axle, and the gears of the electric drive axle rotate at high speed. Due to the influence of manufacturing, etc., there are transmission errors in gear meshing, which easily lead to high-frequency howling complaints of the electric drive axle up to several hundred or even several thousand hertz. In new energy vehicles, especially pure electric vehicles, without the cover of engine noise, the high-frequency sharp howling noise of the electric drive axle becomes more prominent, which easily causes customer complaints. Therefore, the development of electric drive axle howling is particularly important.

[0003] Common causes of electric drive axle howling are as follows: 1. Drive control system failure: The motor of a pure electric vehicle is controlled by an electronic control system. If the control system fails, it may cause the motor to howl. For example, if the capacitor in the motor circuit fails, it will cause the motor to vibrate or make noise; 2. Transmission system failure: Another common cause of motor howling is transmission system failure. For example, if the drive shaft is damaged or worn, it will also cause the motor to howl; 3. Motor quality problems: If there are problems with the motor quality, including the quality of the motor winding, motor overheating, bearing suspension structure design or process problems, etc., will cause the motor to howl. In this case, it is necessary to check and replace the motor to solve the problem; 4. Excessive motor working load: When the vehicle is driving, if the load borne by the motor is too large, it will cause the motor to overheat and howl. Especially when starting or accelerating, the energy consumed by the motor is very large. If it exceeds the load limit of the motor, noise will be generated.

[0004] Currently, the development of howling for gear structure reducers in the market is still in the stage of CAE simulation theoretical analysis, and it is only limited to the analysis of the overall reducer body, and it is impossible to integrate the influence of actual manufacturing. It has certain limitations. And the link that is most likely to have problems is actual production. It is very common that the theoretical calculation is perfect but the howling level of the actually produced product is unsatisfactory. Therefore, it can only be for reference. Summary of the Invention

[0005] The object of the present invention is to provide a calibration method for the howling of an electric drive axle of a new energy vehicle, so as to solve the problem that the development of howling for gear structure reducers in the current market is still in the stage of CAE simulation theoretical analysis, and it is only limited to the analysis of the overall reducer cost body, and the influence of actual manufacturing cannot be integrated, which has certain limitations. And the link that is most likely to have problems is actual production. It is very common that the theoretical calculation is perfect but the howling level of the actually produced product is unsatisfactory.

[0006] To achieve the above object, the present invention provides the following technical solutions: A calibration method for the howling of an electric drive axle of a new energy vehicle, including the following steps: Step 1: Calculate the howling order of the electric drive axle and identify the main howling order and problem points of the electric drive axle through on-vehicle testing; Step 2: Test the overall electric drive axle assembly, its suspension system, and the in-vehicle mode of the cab; Step 3: Analyze the in-vehicle electric drive axle assembly, its suspension system, and the cab mode. If there is modal coupling between the howling of the electric drive axle and the structure, it is necessary to optimize the structure to avoid modal coupling; Step 4: The howling of the electric drive axle is mainly transmitted to the cab response through the path, and the body suspension is an important transmission path. Therefore, it is necessary to control the vibration isolation rate of each body suspension system. If the vibration isolation rate does not meet the target, it is necessary to adjust the suspension parameters to optimize the vibration isolation rate until the target is met; Step 5: After the transmission path is optimized, perform calibration to reduce gear meshing excitation. First, collect each relevant boundary required for the CAE simulation of the electric drive axle, and at the same time clarify the attribute target to be targeted; Step 6: Based on the MASTA simulation software, establish a CAE simulation model of the gear transmission error of each gear pair of the electric drive axle reducer; Step 7: According to the empirical value of the transmission error target, perform CAE simulation and recommend the initial gear modification parameters of the reducer; Step 8: Modify the gears according to the gear modification parameters recommended by the CAE simulation in Step 7 and manufacture samples; Step 9: Install the newly processed gear samples on the vehicle for in-vehicle subjective driving evaluation and objective data test verification. If the verification result does not meet the attribute target, according to the analysis of the measured data, find the torque corresponding to the howling problem point, re-enter it into the CAE simulation to reduce the transmission error of the howling point, recommend a new version of gear modification parameters and conduct in-vehicle verification of the samples. Repeat this cycle iteratively. If necessary, it can be optimized in combination with the calibration strategy until the attribute target is met; Step 10: After the gear modification parameters are determined, conduct a DOE experiment verification on the gear contact pattern of the reducer, mainly conduct a 4-factor 3-level DOE experiment on the position of the contact pattern along the tooth width direction and tooth height direction, the length and width of the contact pattern to determine the tolerance of the design parameters; Step Eleven: After confirming the gear parameter tolerances, increase the sample size to verify production consistency and continuously correct the contact pattern tolerances. Step Twelve: Solidify the parameters related to the transmission path involved in the calibration process, the gear design and modification parameters of the excitation source, and their tolerances, freeze the design and output technical documents to complete the howling calibration of the electric drive axle.

[0007] According to the described method for calibrating the howling of an electric drive axle of a new energy vehicle, in Step One, the actual vehicle test results show that there is obvious 27th-order gear howling during acceleration, corresponding to the order of the first-stage gear of the electric drive axle reducer, to determine that the gear causing the howling is the first-stage gear.

[0008] According to the described method for calibrating the howling of an electric drive axle of a new energy vehicle, in Step Three, the test data shows that the resonance speed of the electric drive axle howling is between 6000 rpm and 7000 rpm, which is converted to a frequency of 2700 Hz - 3150 Hz, close to the motor shaft mode. The howling deteriorates due to resonance with the motor shaft. Thickening the motor shaft makes the motor shaft mode far from 2700 - 3150 Hz and is actually adjusted to 4183 Hz to optimize this mode coupling problem.

[0009] According to the described method for calibrating the howling of an electric drive axle of a new energy vehicle, in Step Four, the control method is to perform acoustic wrapping on the electric drive axle. After wrapping, the howling noise of the electric drive axle is optimized, and the howling noise is optimized by 7.9 dB both for the driver's seat and the near field.

[0010] According to the described method for calibrating the howling of an electric drive axle of a new energy vehicle, in Step Ten, the best position of the gear meshing pattern of the reducer and the acceptable contact pattern range is that the bench test result ≥ 6.

[0011] According to the described method for calibrating the howling of an electric drive axle of a new energy vehicle, in Step Eleven, the sample size is 3 batches, with 30 samples in each batch.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. The howling calibration method for the electric drive axle of a new energy vehicle of the present invention conducts detailed calibration from the excitation source of the electric drive howling to the transmission path (including the electric drive axle itself and the main transmission paths on the vehicle) and then to the response. The CAE simulation analysis is deeply integrated with the actual production and manufacturing, providing a comprehensive, systematic and reliable calibration method for the development of electric drive axle howling. 2. The present invention is not only applicable to the howling calibration of new energy electric drive axles, but also applicable to the howling calibration of hybrid transmissions, and can also be extended to the howling calibration of drive axles and AT / MT transmissions of traditional fuel vehicles.

[0013] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the content of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given and described in detail in conjunction with the accompanying drawings as follows. Description of the Drawings

[0014] Figure 1 is a flowchart of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 2 is a schematic diagram related to Step 1 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 3 is a schematic diagram related to Step 1 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 4 is a schematic diagram related to Step 2 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 5 is a schematic diagram related to Step 3 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 6 is a schematic diagram related to Step 4 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 7 is a schematic diagram related to Step 7 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 8 is one of the schematic diagrams related to Step 9 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 9 is the other schematic diagram related to Step 9 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 10 is one of the schematic diagrams related to Step 10 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention; Figure 11 is the other schematic diagram related to Step 10 of the method for calibrating the howling of the electric drive axle of a new energy vehicle according to the present invention. Detailed Embodiment

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The same components are denoted by the same reference numerals. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the terms "bottom" and "top", "inner" and "outer" refer to the directions towards or away from the geometric center of a specific component, respectively.

[0016] Embodiment: As Figure 1 and Figure 2As shown in the figure, the present invention provides a technical solution: a calibration method for the whine of an electric drive axle of a new energy vehicle, comprising the following steps: Step 1: Calculate the whine order of the electric drive axle and identify the main whine order and problem points of the electric drive axle through on-vehicle tests; Calculate the whine order of the electric drive axle according to the structure of the electric drive axle and the number of teeth of each gear. The calculation is shown in the following table: As Figure 3 shown, there is obvious 27th-order gear whine during acceleration, corresponding to the first-stage gear order of the electric drive axle reducer, so as to determine that the gear causing the whine is the first-stage gear; Step 2: Test the on-vehicle mode of the electric drive axle assembly, its suspension system, and the cab; Test the mode of the motor shaft as Figure 4 shown. The left lower figure is the original designed motor shaft, and the right lower figure is the optimized motor shaft. There is a mode of 2894HZ, and the main vibration mode is at the cantilever end of the motor shaft; Step 3: Analyze the on-vehicle mode of the electric drive axle assembly, its suspension system, and the cab. If there is modal coupling between the whine of the electric drive axle and the structure, it is necessary to optimize the structure to avoid modal coupling; The test data shows that the resonance speed of the whine of the electric drive axle is between 6000rpm - 7000rpm, which is converted into a frequency of 2700Hz - 3150Hz, close to the mode of the motor shaft, and the resonance of the motor shaft deteriorates the whine. Therefore, it is necessary to optimize this modal coupling problem. Thickening the motor shaft makes the mode of the motor shaft far from 2700 - 3150HZ, and it is actually adjusted to 4183HZ.

[0017] As Figure 5 shown, the measured comparison shows that after optimizing the mode of the motor shaft, the optimization effect of the whine of the electric drive axle is obvious, and the peak value drops by about 50%.

[0018] Step 4: Propagate through the body suspension transmission path to the cab response, so as to control the vibration isolation rate of each body suspension system until the target is met. The body suspension is an important transmission path, so it is necessary to control the vibration isolation rate of each body suspension system. If the vibration isolation rate does not meet the target, it is necessary to adjust the suspension parameters to optimize the vibration isolation rate; As Figure 6 shown, taking the acoustic enclosure of the electric drive axle as an example, after acoustic enclosing the electric drive axle, the whine noise of the electric drive axle is significantly optimized, and the main driver and the near field are both optimized by 7.9db; Step 5: After the transmission path is optimized, then carry out the calibration of reducing gear meshing excitation. First, collect all relevant boundaries required for the CAE simulation of the electric drive axle, and at the same time clarify the attribute targets to be targeted; Step 6: Establish the CAE simulation model of the gear transmission error of each gear pair of the electric drive axle reducer based on MASTA simulation software; Step 7: Based on the target empirical value of the transmission error, CAE simulation is performed to recommend the initial modification parameters of the reducer gear; like Figure 7 As shown, the example shaping parameters and simulation results are as follows: Step 8: Perform gear shaping processing according to the gear shaping parameters recommended by the CAE simulation in step 7 to produce a sample; Step 9: The newly processed gear samples are loaded on the vehicle for subjective driving evaluation and objective data testing; If the verification result does not meet the attribute target, find the torque corresponding to the howling problem point based on the analysis of the measured data, re-enter the CAE simulation to reduce the transmission error of the howling point, recommend a new version of the gear modification parameters and do a sample vehicle verification, and repeat the cycle iteratively. If necessary, optimize it in combination with the calibration strategy until the attribute target is met; The modified sample produced in step 8 is installed on the vehicle for verification. If the result is not satisfactory, the parameters are adjusted according to the actual verification result. For example, if the actual vehicle verification shows that the small torque is acceptable but the large torque is unacceptable, the next version of CAE simulation modification is optimized for the large torque, and then the new modification parameter sample is verified, and it is iterated continuously until it is acceptable or the goal is achieved. Figure 8 As shown, it is the result after multiple rounds of iterations; like Figure 9 As shown, scheme G has the best effect, and the contact spot of the gear is centered and evenly distributed, which is a more ideal state.

[0019] Step 10: After the gear modification parameters are determined, the contact spots of the reducer gears are verified by DOE experiments. The 4-factor 3-level DOE experiments are mainly conducted on the positions of the contact spots along the tooth width and tooth height directions, and the length and width of the contact spots to determine the design parameter tolerances. like Figure 10 As shown, the meshing contact spots of the electric drive axle reducer gear are continuously adjusted, and samples are made for actual vehicle verification. The range of the gear meshing contact spots corresponding to the acceptable squeal of the electric drive axle is found, as well as the distribution range in the tooth width direction and tooth height direction. like Figure 11 As shown, the optimal position of the reducer gear meshing spot and the acceptable contact spot range can be found as quickly as possible through the following 4-factor 3-level DOE experiment. (Bench results ≥ 6 are acceptable) Step 11: After the gear parameter tolerance is confirmed, increase the sample size (usually 3 batches, with about 30 samples in each batch) to verify production consistency and continuously correct the contact spot tolerance; In the actual manufacturing process, the acceptability of a batch of samples does not necessarily mean that mass production will also be acceptable. Therefore, it is often necessary to conduct multiple batches with a large sample size for verification. Only after the verification is acceptable can the tuning result of the electric drive axle whine be considered successful, stable, and mass-producible. Therefore, increase the sample size (usually conduct 3 batches, with about 30 samples in each batch) to verify production consistency and continuously correct the contact spot tolerance; Step Twelve: Solidify the transfer path-related parameters, excitation source gear design and modification parameters, and their tolerances involved in the tuning process, freeze the design, and output technical documents to complete the tuning of the electric drive axle whine; After the tuning is completed, all important parameters involved need to be solidified and technical documents need to be formed for the convenience of production manufacturing and subsequent quality inspection.

[0020] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0021] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Claims

1. A method for adjusting the howling of the electric drive bridge of a new energy vehicle, characterized in that: The following steps are involved: Step 1: Calculate the electric drive axle howling order and conduct actual vehicle testing to identify the main orders and problem points of the electric drive axle howling; Step 2: Test the electric drive axle assembly and its suspension system, as well as the actual vehicle mode of the cab; Step 3: Analyze the actual vehicle electric drive axle assembly and its suspension system, as well as the cab mode; Step 4: Transmit the response to the cab through the body suspension transfer path to control the vibration isolation rate of each body suspension system until the target is met; Step 5: After the transmission path is optimized, adjust the gear meshing excitation. Step 6: Establish the CAE simulation model of the gear transmission error of each gear pair of the electric drive axle reducer based on MASTA simulation software; Step 7: Based on the target empirical value of the transmission error, CAE simulation is performed to recommend the initial modification parameters of the reducer gear; Step 8: Perform gear shaping processing according to the gear shaping parameters recommended by the CAE simulation in step 7 to produce a sample; Step 9: The newly processed gear samples are loaded on the vehicle for subjective driving evaluation and objective data testing and verification; Step 10: After the gear modification parameters are determined, the contact spots of the reducer gears are verified by DOE experiments. The 4-factor 3-level DOE experiments are mainly conducted on the positions of the contact spots along the tooth width and tooth height directions, and the length and width of the contact spots to determine the design parameter tolerances. Step 11: After the gear parameter tolerance is confirmed, increase the sample size to verify production consistency and continuously correct the contact spot tolerance; Step 12: Solidify the transmission path related parameters and excitation source gear design and modification parameters and their tolerances involved in the adjustment process, freeze the design and output the technical files to complete the electric drive axle howling adjustment.

2. The method for adjusting the whine of the electric drive bridge of a new energy vehicle according to claim 1 is characterized in that: In step one, the actual vehicle test results show that there is obvious 27th-order gear whine during acceleration, which corresponds to the first-stage gear order of the electric drive axle reducer, so as to determine that the gear causing the whine is the first-stage gear.

3. The method for adjusting the whine of the electric drive bridge of a new energy vehicle according to claim 1 is characterized in that: In step three, the test data shows that the resonant speed of the electric drive axle howling is between 6000rpm-7000rpm, which is converted to a frequency of 2700Hz-3150Hz, which is close to the motor shaft mode. Resonance with the motor shaft worsens the howling. Thickening the motor shaft makes the motor shaft mode away from 2700-3150HZ, and is actually adjusted to 4183HZ to optimize the modal coupling problem.

4. The method for adjusting the whine of the electric drive bridge of a new energy vehicle according to claim 1 is characterized in that: In step four, the control method is to acoustically wrap the electric drive axle. After wrapping, the howling noise of the electric drive axle is optimized, and both the main driver and near field are optimized by 7.9db.

5. The method for adjusting the whine of the electric drive bridge of a new energy vehicle according to claim 1 is characterized in that: In step ten, the optimal position of the reducer gear meshing spot and the acceptable contact spot range are bench results ≥ 6.

6. The method for adjusting the whine of the electric drive bridge of a new energy vehicle according to claim 1 is characterized in that: In step 11, the sample size is 3 batches, with 30 samples in each batch.

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