The vibration signal of the planetary gearbox shows complicated modulation sidebands no matter the gear is normal or fault. It leads to a challenge in the fault diagnosis, especially for the localized faults which stimulate resonance modulation phenomena. To reveal the resonance modulation mechanism of sun gear’s localized fault, the vibration signal model is built based on the convolution of transient impact force and transfer function of the planetary gearbox. Three prominent transfer paths including modal parameters of the flexible ring gear or housing are involved to obtain resonance modulation sidebands. A projection function is used to model the time-varying direction of transient impact force. Resonance modulation sidebands of a single planet gear meshing is first deduced, and then the sidebands related to multiply planet gears meshing. The resonance modulation of localized fault on sun gear are concluded to be consist of three groups of sidebands. The proposed model is verified by the good consistency between simulation and experimental testing on a commodity planetary gearbox. It contributes an important and effective frequency indicator to confirm the condition of planetary gearboxes.

无论齿轮正常还是故障，行星齿轮箱的振动信号都呈现出复杂的调制边带。这给故障诊断带来了挑战，特别是对于激发共振调制现象的局部故障。为揭示太阳轮局部故障的共振调制机制，基于瞬态冲击力与行星齿轮箱传递函数的卷积，建立了振动信号模型。三个突出的传递路径包括柔性齿圈或外壳的模态参数，以获得谐振调制边带。投影函数用于模拟瞬态冲击力的时变方向。首先推导出单个行星齿轮啮合的共振调制边带，然后推导出多个行星齿轮啮合的相关边带。太阳轮局部故障的共振调制由三组边带组成。通过对商品行星齿轮箱的仿真和实验测试之间的良好一致性验证了所提出的模型。它为确认行星齿轮箱的状况提供了重要而有效的频率指标。