一种机载HUD用分离机构分离值的设计及试验验证

Design and Test Verification of Separation Value of Separation Mechanism for an Airborne HUD

机载平视显示器(HUD)用的折转机构在飞机应急着陆出现纵向负加速度≥9.0g时,飞行员前方的组合镜须在惯性力作用下分离移出飞行员头部前冲的运动轨迹之外。设计了一种凸轮与拉簧推杆联合作用的分离机构来完成此功能,通过控制拉簧的力值来实现分离机构的分离阀值。分别以凸轮转轴和推杆转轴为矩心进行受力分析,计算推导了负9.0g加速度值与弹簧力值的关系,设计出相应的拉簧。利用SolidWorks Motion软件通过设置接触、弹簧参数,采用直线马达加速度驱动形式加载,加速度曲线为三角形波形,进行了分离值仿真,通过对比设置的加速曲线及弹簧拉伸长度变化曲线,得到分离机构分离时的加速度值为9.98g。在结构动态冲击试验台上,按仿真加速度曲线值进行加载、采用高速摄像机对组合镜分离角度摄像记录,完成了试验验证,对比测定的加速度曲线及组合镜分离角度变化曲线,得到了分离机构的分离阀值为负10.13g。试验曲线与仿真曲线结果基本一致,表明分离机构能够按照设计要求进行分离,满足机载安全要求。

When negative longitudinal acceleration≥9.0g occurs in the aircraft emergency landing,the composite mirror in front of the pilot must be separated and moved out of the pilot’s head forward movement track under the action of inertia force.A separation mechanism of CAM and stretch spring push rod is designed to accomplish this function,and the separation threshold of the separation mechanism is realized by controlling the force value of the stretch spring.The force analysis was carried out with the CAM shaft and the push rod shaft as the moment center respectively.The relationship between the negative 9.0g acceleration value and the spring force value was calculated and deduced.Thus the corresponding tension spring was designed.Solidworks Motion software was used to set the contact and spring parameters.With linear motor acceleration driving form loading and triangular acceleration curve,separation value simulation was carried out.By comparing the acceleration curve and spring stretching length curve set,the separation mechanism acceleration value is 9.98g.On the dynamic impact test bench of the structure,loading was carried out according to the simulated acceleration curve value,and a high-speed camera was used to record the separation angle of the composite mirror to complete the test verification.By comparing the measured acceleration curve and the separation angle change curve of the composite mirror,the separation threshold of the separation mechanism was obtained to be negative 10.13g.The results of test curve and simulation curve are basically consistent,indicating that the separation mechanism can be separated according to the design requirements and meet the requirements of airborne safety.