Vibration characteristics of high speed helical gear transmission under combined excitation

In order to study the influence degree of two kinds of excitation factors on the system vibration, the vibration speed diagram of single-stage helical gear transmission gear face meshing line direction under three kinds of excitation forms when the input torque is 100 N · m is compared, as shown in Fig. 1.

Figure 1 It can be seen that the system vibration response under the meshing impact excitation is greater than that under the time-varying meshing stiffness excitation; this is because the mean value of the time-varying meshing stiffness of the gear pair is large, and the vibration response of the system under the excitation of the time-varying meshing stiffness is relatively small. However, when the speed and torque are constant, the meshing impact force is large, so the system vibration produced by meshing impact excitation is obvious at low speed In the over resonance region, with the increase of rotating speed, the system vibration under meshing impact excitation is consistent with that under comprehensive excitation, which indicates that the influence of time-varying meshing stiffness on system vibration is less and less at high speed, and meshing impact is the main excitation component of the system.

In order to compare the vibration response of the system under three excitation modes, the frequency domain diagram of 15000rpm single-stage helical gear drive under three excitation modes is made, as shown in Fig. 2.

Figure 2 shows the frequency domain response of single-stage helical gear transmission under three different excitations at 15000rpm. It can be clearly seen from the figure that the amplitude of frequency doubling is the largest, which is because the amplitude of frequency doubling is the highest, and the frequency doubling is closest to the resonance frequency at this speed; under the excitation of time-varying meshing stiffness, the third harmonic basically decays to zero, while in the presence of impact excitation component, 20 The frequency doubling still has a certain amplitude and the attenuation is slow. This is due to the complex frequency of the meshing impact excitation and the high-order harmonics generated by the system, that is, the existence of the impact excitation makes the vibration of the system more complex. This situation is more prominent in the high-speed gear system, so the shock component should be considered more in the vibration reduction optimization of high-speed gear transmission.

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