非线性振动冲击现象误认为变速器空转敲击

Non-Linear Vibro-Impact Phenomeron Belying Transmission Idle Rattle

本文研究汽车变速箱齿轮的敲击。特别研究空转敲击,主要对轻负荷下轮齿的重复撞击。润滑的液体动力学状态克服了轮齿副间的轻载撞击,由于夹带润滑油运动和挤压油膜的影响组合构成了润滑油膜。开发了由一对松动齿轮结合的一对轮齿的液体动力撞击和齿面摩擦组成的概括性参数惯性动力模型。总模型包括了对松动齿轮副和刚体输入和输出变速器轴的侧向运动。因此,确定了油膜特性对空转齿轮敲击的影响,迄今这方面还没有足够的研究。齿轮敲击用振动符号来表示,它相当于因发动机扭转振摆、啮合频率和润滑剂联接的撞击特性造成的频率带。该频谱图受润滑油流变学的影响,特别其大多数粘度随温度变化。已经发现因为温度升高而润滑油刚度降低,随着润滑油粘度降低频谱排列趋向于低频率。该结果在本文报导中已由实验证实。同时它还表示挤压油膜的运动在变速器产生敲击倾向有十分显著的作用。

This paper investigates automotive transmission gear rattle. Specifically, idle gear rattle, where the repetitive impacts of teeth are subject to light loads in investigated. Hydrodynamic regime of lubrication prevails in lightly loaded impact of teeth pairs. Formation of a lubricant film is due to the combined entraining motion of the lubricant and squeeze film effect. A lumped parameter inertial dynamic model, comprising hydrodynamic impact and flank friction for pairs of simultaneous teeth pairs of loose gears is developed. The overall dynamic model includes seven loose gear pairs and rigid body lateral motions of input and output transmission shafts. Therefore, the influence of fluid film behaviour on idle gear rattle is determined, which has hitherto not attracted sufficient research studies. Gear rattle is manifested by a vibration signature, which corresponds to the bands of frequencies due to torsional engine oscillations, meshing frequencies, and impact characteristics of lubricated conjunctions. The spectral contributions are affected by lubricant rheology, specifically its bulk viscosity variation with temperature. It has been found that spectral disposition tends towards lower frequency contributions with reducing lubricant viscosity because of rising temperatures and lowering lubricant stirfhess. The findings conform with the experimental results, also reported in the paper. It has also been shown that squeeze film motion palys a significant role in the propensity of transmission system to rattle.