Mechanism of vibration and noise in gear transmission system

In the hybrid drive mode, engine ice, large motor E2 and small motor E1 are in working state, while the gear transmission system of hybrid electric vehicle is composed of composite planetary gear mechanism and parallel shaft gear mechanism. Kahraman once pointed out that the vibration characteristics of composite planetary gear transmission system will be more complex. The dynamic excitation of multiple pairs of teeth meshing in the composite planetary gear system, the dynamic excitation of gear meshing of the parallel shaft gear mechanism itself, the vibration of the engine, large and small motors, the vibration and load change of the working mechanism are the main sources of the noise of the gear transmission system of the hybrid electric vehicle. Among them, internal excitation and external excitation are two types of dynamic excitation of gear transmission system.

The external excitation of hybrid electric vehicle power transmission system refers to the driving torque of engine and large and small motors and the resistance and resistance torque of load. The internal excitation in the system mainly refers to the stiffness excitation, meshing impact and error excitation in the meshing process of each pair of gear pairs in composite planetary gear mechanism and parallel shaft gear mechanism. The dynamic excitation of gear meshing leads to the vibration of the system and the vibration and noise of the system. Therefore, not only the dynamic excitation force of gear meshing in the system will affect the noise intensity of the gear system, but also the structure, dynamic characteristics and transmission characteristics of dynamic meshing force among wheel body, transmission shaft, bearing and box will also affect the noise intensity of the system.

The generation and propagation mechanism of vibration and noise in the gear transmission system of the hybrid electric vehicle is usually related to the following problems:

(1) This paper mainly studies the vibration characteristics of hybrid electric vehicle in hybrid drive mode. Under this working condition, the transmission system shows very complex vibration characteristics. In addition, there are the effects of gear types, the selection of design parameters, the accuracy and error of gear machining process and the error in assembly process on the dynamic meshing force of gear teeth in the system;

(2) According to the helical gear in the gear transmission system, the dynamic equation of the corresponding gear system is established, and the vibration form of the system under the action of dynamic excitation force is studied;

(3) The vibration characteristics of gear teeth, bearings, transmission shafts and other components in gear transmission system, the process and characteristics of transmission from meshing teeth to the surface of gearbox box;

(4) For the acceleration noise caused by the impact of gear teeth, which makes the gear produce great acceleration and disturbs the surrounding environment, the meshing impact of gear occurs in the direction parallel to the shaft. Therefore, it is necessary to discuss how the acceleration noise is transmitted to the outside through the box.

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