# Analysis of meshing impact excitation of hypoid gear

Meshing impact is another factor that produces vibration and noise in the process of hypoid gear transmission. It is caused by the rotation speed mismatch of the active and passive gears of the hypoid gear caused by the tooth deformation and machining error of the hypoid gear in the meshing process, which mainly occurs in the meshing position of the hypoid gear teeth. Therefore, in order to simulate the meshing impact process, it is necessary to accurately solve the meshing in and out position of hypoid gear teeth and the maximum value of the speed difference between active and passive wheels.

The two parameters are calculated by dynamic contact finite element analysis method. In the calculation, the angular velocity of the driving wheel under the working condition is calculated, the corresponding torque of the driven wheel is loaded, and the angular velocity of the driven wheel is taken as the output variable. In the whole meshing process, the impact meshing position and speed fluctuation are determined by observing the fluctuation of the angular velocity of the driven wheel when entering the meshing. The relative meshing impact speed of the driving wheel relative to the driven wheel is obtained by multiplying the speed fluctuation amplitude of the driven wheel by the transmission ratio. Then the dynamic contact analysis and calculation model is re established. Adjust the meshing impact position of the active and passive gears, load the impact speed on the driving wheel, and load the working torque on the passive wheel. The impact force curve can be obtained by taking the comprehensive contact force of the tooth surface of the hypoid gear in the collision process as the output. As shown in the figure, it is the speed curve of a pair of 10×41 hypoid gear driven wheels analyzed according to the above method. The figure shows that after the speed is stable, the fluctuation of the speed at the meshing in and meshing out position is very small, and the maximum amplitude is about 0.24rad/s. It can be analyzed that under the speed impact of 0.24rad/s, the impact force is much smaller than the meshing stiffness excitation force, which can be ignored. We know that the speed fluctuation and impact force in the meshing process are greatly affected by the coincidence degree of the gear pair in the meshing process. For hypoid gears, there are basically 2-3 teeth participating in meshing at the same time every instant. Therefore, this situation is likely to be caused by the large helix angle and high coincidence degree of hypoid gear.

In order to verify the correctness of this method in analyzing meshing impact, a pair of 10×18 spur bevel gear pairs with small coincidence degree and equal modulus are selected for the above analysis. As shown in the figure, the red curve is the speed curve of the driven wheel. It can be seen that there is obvious speed fluctuation when meshing in and out, and the fluctuation amplitude is about 3.7rad/s. The above results show that without considering the influence of hypoid gear machining error (mainly tooth splitting error), the meshing impact force of gear with small coincidence has a great influence on the internal excitation. However, for the hypoid gear pair transmission with large coincidence degree, the meshing impact excitation is not the main excitation component. Therefore, the meshing stiffness excitation is mainly considered in the analysis of its meshing internal excitation.

Scroll to Top