直线式作动器中精密行星传动的承载能力研究

【作者】 刘佳；

【导师】 王华坤；

【作者基本信息】 南京理工大学 ， 机械设计及理论， 2011， 硕士

【摘要】 空间飞行器直线式作动器精密行星传动是重要的动力传动部件,要求体积、质量最小化,承载能力最大化,综合性能最优化。由于其技术指标要求极其苛刻,短时过载力矩是通用行星传动的数倍,可靠性要求极高,因此强过载下精密行星传动的设计理论是一关键技术瓶颈,目前没有完整的设计规范。文中重点对直线式作动器精密行星传动承载特性进行研究,旨在通过研究找出提高承载能力的规律,为合理设计提供理论依据。首先对作动器精密行星传动的强度进行理论计算,通过不同计算方法的比较,提出了适用于精密行星传动的齿根弯曲强度和齿面接触强度的计算准则。针对作动器的工作特点,研究认为齿根压缩侧的应力不可忽略,由此推得齿根压缩侧应力的计算式。然后综合强过载下众多影响承载的因素,推导出有别于通用齿轮设计的强度校核公式。根据齿轮啮合原理找出了五个特殊啮合状态,并在不同的载荷即：额定载荷、两倍额定载荷、三倍额定载荷下,充分考虑摩擦、齿根过渡曲线圆角等的影响,应用有限元分析得到啮合齿廓的应力分布规律,提出强过载下如何提高强度的技术措施。文中详细分析了制造、装配误差对精密行星传动承载能力的影响,建立了基于质量一弹簧的均载计算模型,并用精密行星传动装配体有限元离散模型进行了验证。分析了在强过载工况下,存在误差时精密行星传动的承载特性,找出了各种误差对均载的影响程度。最后利用精密行星传动装配体有限元离散模型,分析了在强过载工况下,不同内齿圈轮缘厚度对内齿圈应力、变形及行星轮均载比例的影响,为合理设计内齿圈结构提供理论依据。更多还原

【Abstract】 Precision planetary transmission of electromechanical actuator(EMA) in aerocraft is an important transmission components which required volume, mass minimization, the carrying capacity maximization, integrated performance optimization. As extremely harsh Technical requirements, high reliability and short-term overload is several times of common planetary transmission, precision planetary transmission design theory is a key technology bottlenecks, there is no complete design specification. This paper focuses on the load characteristics of precision planetary transmission, designed to increase carrying capacity through research to find out the law, provide a theoretical basis for the rational design.Firstly, the precise theory of planetary transmission based on analytical method is established by comparison of different calculation methods on root bending strength and tooth contact strength; the tooth root stress on compression side cannot be ignored in the final analysis, and the formulas of the tooth root strength on compression is established; research suggests that the tooth root stress on compression side cannot be ignored, thus the formulas of the tooth root strength on compression is established.Secondly, five special mesh positions are fixed based on the theory of gear mesh, and the deformable body model considering friction and the fillet of root under the rated load, twice rated load, thrice rated load is analyzed to compare the stress, some suggestions are listed to enhance the load capacity on high overload condition.Thirdly,.the influence of errors on planet load sharing is researched. The manufacturing errors and assembly errors is listed and analyzed, and a simplified discrete model is established, The accuracy of the discrete model is quantified by comparing its predictions to the predictions of the finite element model. Two models is used to quantify the influence of errors on gear bending stresses, and on planet loads on the condition of high over load.In the end, the influence of ring gear rim thickness on the stress, strain and planet load sharing on the condition of high over load is analyzed by using the finite element model of the whole planetary transmission which provide a theoretical basis for the design.更多还原