# Study on Optimization of gear parameters of automobile transmission

With the development of automobile towards high performance, gear system should meet the requirements of high efficiency, high reliability, high stability, high speed and heavy load, lightweight, low vibration, low noise and short design cycle. Under the background of the current development of manufacturing industry towards intelligence and information, the design method of gear system should also have the characteristics of intelligence and information to meet the above requirements of gear system. However, the traditional gear design mostly depends on experience, and the design parameters are mostly obtained through experiments. The design cycle is long and the performance of gear system has great limitations, which can not meet the current requirements There are many requirements for the performance of gear system. At present, the wide application of CAD 3D design software and CAE analysis software in mechanical design makes it possible for the new design method of gear system. However, UG, Pro / E, CATIA and other CAD software can only design some simple gears, which can not fully meet the requirements of gear parametric modeling. It is necessary to carry out secondary development of these software, and because of CAD and CAE There are some problems in the compatibility of different programming languages used in the software, so it is difficult to use CAD and CAE software to design gears directly. This paper attempts to use a programming language to complete the three-dimensional modeling design and performance analysis of gears, and to realize the integration of CAD and CAE of gear design. The gear of automobile transmission is studied, and the design of involute spiral gear is completed by using CAD and CAE software. The research work completed is as follows:

1) The mathematical model of involute spiral tooth surface is established, and the relevant parameters in the mathematical model are studied. As the basis of establishing the accurate involute gear model, it is ready for the comprehensive analysis of the performance of the gear pair. By further studying the basic meshing law of tooth profile, the equation of meshing line is derived, the mathematical model of gear pair considering the assembly error is established, and the analysis of the problems in the process of gear pair assembly is completed, which provides the theoretical basis for virtual assembly of gear pair in computer, avoids blind assembly only relying on experience, and has the same effect on the actual gear pair assembly Guiding significance.

2) On the basis of ANSYS parametric language and involute helical tooth surface equation, this paper establishes an accurate involute helical gear model, which can contain many kinds of gear parameters, so the gear 3D model established in this paper can realize all kinds of modeling, so the gear model established in this paper is more similar to the actual gear, and as a gear CAE The basis of the analysis. In order to further study the assembly problem of gear pair under three-dimensional modeling, in ANSYS In the software, the three-dimensional assembly model of the gear pair is established through the parametric language. The model and the mathematical model of the gear pair are analyzed and compared. In these two models, the problem of the virtual assembly of the gear pair can be effectively solved, which shows that the mathematical model of the gear pair assembly established in this paper is correct. In order to analyze the performance of the gear pair, this paper studies the loading boundary conditions in the three-dimensional assembly model of the gear pair, and establishes the finite element contact model of the gear pair in the ANSYS software. The results show that the CAD model and CAE model of the gear set up in this paper are compatible, which also provides the possibility to analyze the mechanical properties of the gear pair.

3) The dynamic meshing of the gear pair is studied, and the contact condition of the model is studied when the rotation angle is – 10 ° ~ 10 °. The results show that the contact area of the gear pair fluctuates with the change of the rotation angle. At a certain rotation angle, the contact area changes abruptly, and the transmission stability of the gear pair is the worst. The results show that the transmission stability of the gear pair is dynamic, and the contact degree is used to study On the basis of contact area, this paper defines the transmission stability to study the transmission stability, which can effectively reflect the dynamic meshing of gear pairs. Based on the finite element contact model of gear pair, the optimization model of gear pair is established with the transmission smoothness as the optimization objective. In the software ANSYS and MATLAB, the orthogonal experimental design and genetic algorithm are used to solve the optimization model, and the optimization parameters and parameters before optimization are analyzed in the angle of – 5 ° ~ 5 ° transmission smoothness. The results show the effectiveness of the optimization model of gear pair. On the basis of the optimization model of gear pair, the model verification and theoretical explanation of the transition state of gear pair engagement are also carried out in this paper, and the effectiveness of the optimization model is verified by using kisssoft. The results further show that in the ANSYS and MATLAB software, the combination of CAD and CAE is feasible.

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