With the continuous development of the automotive manufacturing industry, the gear property of electric vehicles has becomeWith the continuous improvement of energy requirements, relevant researchers are actively trying to reduce gear vibrationand the noise generated during the operation of the gear. To achieve this goal,Researchers attempted to establish a three-speed gearbox model, based on which they designed a gear shift systemStatic analysis and modal analysis of the transmission system of the transmission box are conducted to optimize the transmission system.The dynamic system provides data information.
This study focuses on the three-speed transmission of electric vehicles, which isIt mainly consists of two parts: the transmission mechanism and the operating system (as shown in Figure 1).
It can be found that the gearbox has four pairs of gear powerThe transmission system, based on the specific parameters of each gear transmission system,Utilize MASTA software to establish a dynamic simulation model. In traditional transmission models, the bearings and gears inside the transmission are regarded as rigid bodies, and the rigid body dynamics model is used to simulate the motion of the transmission.The stiffness of the body is set to infinityGear hub and bearing are not consideredElastic deformation that may occur during the operation of the part may lead to discrepancies between simulation data andThe real working state of the transmission does not match. To solve this problem, in this study,Substitute the stiffness matrix, mass matrix, and other information of bearing hubs, shells, and other partsIntroduce the model, and connect its cluster nodes to the corresponding bearings to form a complete mechanical structure.This way, the influence of the overall rigidity of the gearbox is introduced into the simulation,The experimental data is more closely related to the real state of the gearbox.
Analyze the vibration problem of the gearbox and analyze its internal correlationThe safety factor of parts and the damage rate of parts are important starting points.Researchers determined the reliability of the gear transmission system through static analysis.In the study, due to the high loads borne by the bearings and gears in the gearbox,Therefore, researchers focus on the deformation of bearings and gears.Perform static analysis.The main function of the wheel parts is to transmit power. OnceProblems with its stability and safety will affect the overall stability of the transmission.Researchers based on safety factors, injury rates, and error amountsThree indicators provide a scientific analysis of the safety of gear parts.
The safety factor of gear, which is the ratio of allowable stress to actual stressFor example, the factor includes two indicators: bending safety factor and contact safety factor.Ideally, the gear safety factor should be greater than 1, but in the actual preparation of gear parts,During the assembly of parts, errors are inevitable. Therefore, it is necessary to take the errors into account and increase the gear safety factor to >1.1 to ensure the safety of the gear.The safety of the parts. When the transmission is in the first gear state, the internal gears usedWhen the wheel parts are engaged, the impact load on the gear is the highest in this state.Therefore, the researchers conducted a study on gear parts based on the transmission gearbox I state.Static analysis. Through static analysis, the researchers found that among the four groups of gears, the bendingThe minimum value of the safety factor for the curve is 1.1525, and the maximum value is 1.406; contact safetyThe minimum value of the coefficient is 1.336, and the maximum value is 1.7004, both of which are higher than 1.1, proving thatWhen the transmission is in gear I, the safety factors of all gear parts meet the requirements.Please, no need to replace parts or modify the gear。
Important parts of the gear, the transmission has been operatedDuring the process, the force of the bearing is transmitted to the transmission shaft, which may cause the transmission shaft toIn addition, the bending moment and torque generated during the operation of the transmission shaft can alsoleading to plastic deformation or fatigue failure problems.Once it is transmittedDeformation or breakage of the moving shaft can cause vibration in the transmission. Therefore, researchersPerform static analysis on the four transmission shafts in the transmission box to determine the reliability of their transmission system.Reliability.
Macro parameters of gears include the number of teeth, helix angle, tooth width, etc.In most cases, the performance of a gear is determined by a combination of multiple parameters.determinedlyTherefore, researchers strive to obtain the best comprehensive performance of the gear.Yes, actively try to optimize the macro parameters of gears. To solve the problem of transmission gearFor the problem of wheel vibration, the researchers take into account both macro-optimization efficiency and effectiveness,Select the optimal coincidence degree. Among the many factors that affect the stability of the gear transmission system,In the case of plain gears, the degree of coincidence is a more important factor. The higher the degree of coincidence of gears, the more accurate theThe smoother the transmission is, the less vibration the transmission gearbox will have; otherwise, it will cause transmission system failure.The resonance phenomenon reduces the reliability and service life of the transmission. In addition, eachThe smaller the load a gear bears, the longer its service life will be.Upgrading.
To further reduce the vibration of the gearbox, researchersBased on the optimization of the parameters, the gears are micro-modified. GearboxThe microscopic modification of gears includes tooth surface treatment, tooth profile design, and modulus correction.The tooth surface treatment generally includes heat treatment, surface treatment, grinding and other technologies.Through microscopic modification, the hardness, wear resistance, and accuracy of the tooth surface can be improved.The tooth design refers to the effective design of the gear according to the transmission requirements of the gear.Method: Make the load distribution of the gear reasonable to meet the transmission requirements; modulus correctionAfter the design of the tooth profile, according to the actual situation, by adjusting the modulus parameters,The tooth profile is more reasonable, thus improving the transmission efficiency. Currently commonly used tooth profile modificationThe method includes two types of modification: helical angle modification and tooth bulge modification. The former is achieved by adjustingThe size of the helix angle, which allows the actual tooth surface of the gear to be at a different position from the theoretical tooth surfaceUnder the condition of repairing it. Due to the design and processing of gear manufacturers,When rotating, it is difficult to control the change in helical angle. Therefore, the tooth directionDrum shaping has become a more effective and accurate method of gear shaping.
Researchers try to increase the gear overlap angleThe modulus, number of teeth, and helical angle can be adjusted without changing the rigidity of the gear.The parameters are optimized and adjusted. Before optimization, to ensure the strength of the gears is fullyIn order to meet the requirements and maintain the gear tooth width unchanged, researchers optimized the gear designFive constraints were imposed, namely: gear slip rate <3; gear notWith a tooth top thickness greater than 0.25 times the modulus value; the transition curve does not interfere; teethThe top clearance exceeds 0.15 times the value of the modulus. Based on these five constraints, researchThe personnel set the pressure angle to 20° and the modulus to the standard modulus to ensure the teethThe wheel top height coefficient is consistent with the top clearance coefficient, and the parameters of the gear are optimized.
As the core component of the automotive transmission system, the stability of the transmissionReliability has a direct impact on the driving experience and safety of cars.Therefore, the researchers conducted in-depth analysis on the causes of vibration in the transmission.Using static analysis and modal analysis, we can find the causes of gear changes.The reasons for the vibration of the gearbox, and the optimization of the macro parameters of the gearbox through the analysis of the dynamic characteristics of the gearbox.Reduce gear load fluctuations and avoid parts such as gears, bearings, and drive shaftsDeformation under the action of load force provides assistance for the development of automobile manufacturing industry.