车载空调压缩机的运动精度分析与公差优化设计

发布时间：2018-05-02 16:20

本文选题：摇摆斜盘式传动机构 + 排量　；参考：《湖南科技大学》2016年硕士论文

【摘要】：变排量车载空调压缩机SD7V16,其关键机构—摇摆斜盘式传动机构,可以将主轴的高速旋转运动,传递为活塞的压缩、排气、膨胀、吸气四个工作过程。SD7V16利用斜盘倾斜角的变化来改变活塞的行程,从而实现排量的可连续变化,最终实现SD7V16可根据实际工况随时匹配相应的制冷量。SD7V16车载空调压缩机有七个活塞和气缸,由一个活塞行程偏差引起的排量的微小偏差可能宏观上感觉不到。因主轴允许持续转速最高可达7000r/min,若七个活塞均有一定程度的行程偏差,则在一段时间内累积的总排量偏差,是不可忽略的,甚至可能影响到宏观上汽车空调制冷的效果。因此,对SD7V16的摇摆斜盘式传动机构展开运动精度分析与公差优化设计具有重要意义。本文,以SD7V16的摇摆斜盘式传动机构为主要研究对象,展开考虑制冷性能约束的关键零部件尺寸公差优化设计。全文具体研究内容如下:(1)介绍了SD7V16的结构,分析SD7V16型车载空调压缩机的调温原理与排量控制原理。还介绍了制冷剂R134a、制冷性能参数COP、排量与制冷量的计算。对SD7V16斜盘倾斜角与活塞行程关系进行了实验,得出24组数据,将实验数据曲线拟合与理论计算出的方程曲线进行对比与分析。对某工况下SD7V16的制冷量进行了计算。(2)根据SD7V16关键机构的传动原理,建立数学模型,对关键机构进行了运动学分析。得出了活塞的位移、速度、加速度计算公式,进而求出排量的几何算法。引入关键零部件尺寸偏差,分析了活塞的运动精度,及其运动精度对排量的影响。通过Adams对SD7V16关键机构进行虚拟样机仿真,仿真结论验证了基于该数学模型的理论思路可行,计算结果正确。(3)根据求出的排量与关键尺寸的函数关系,并根据排量与制冷量的函数关系,进而求出制冷量与关键尺寸的函数关系。求解最大斜盘倾斜角24°时,制冷量偏差ΔQ0与压缩机关键零部件尺寸偏差的偏微分方程,做为关键零部件尺寸公差优化的性能约束。最后引入关键零部件尺寸公差的经济加工精度约束,结合调研数据。以质量损失成本与加工成本之和为目标函数(求最小值),基于MATLAB遗传算法,求解公差优化模型。
[Abstract]:Variable displacement air conditioner compressor SD7V16, its key mechanism-swinging skew disk transmission mechanism, can be the spindle of high-speed rotation motion, transfer to the piston compression, exhaust, expansion, Inhale four working processes. SD7V16 changes the stroke of the piston by changing the tilting angle of the tilted disk, thus realizing the continuous variation of the displacement. Finally, according to the actual working conditions, SD7V16 can match the corresponding refrigerating capacity. SD7V16 air conditioner compressor has seven pistons and cylinders. The small deviation of displacement caused by one piston stroke deviation may not be felt macroscopically. Because the maximum continuous rotation speed of the spindle can be as high as 7 000 r / min, if the seven pistons have a certain degree of stroke deviation, the total displacement deviation accumulated in a period of time can not be ignored, and may even affect the effect of automobile air conditioning refrigeration on the macro scale. Therefore, it is of great significance to analyze the unfolded motion accuracy and the tolerance optimization design of SD7V16 swing skew drive mechanism. In this paper, the swing skew disk transmission mechanism of SD7V16 is taken as the main research object, and the dimension tolerance optimization design of key parts considering refrigeration performance constraints is carried out. The structure of SD7V16 is introduced, and the principle of temperature regulation and displacement control of SD7V16 type air conditioner compressor is analyzed. The calculation of refrigerant R134a, refrigeration performance parameter COP, displacement and refrigerating capacity are also introduced. The relationship between tilting angle and piston stroke of SD7V16 obliquity disk is tested and 24 groups of data are obtained. The curve fitting of experimental data and the equation curve calculated theoretically are compared and analyzed. The refrigerating capacity of SD7V16 under a certain working condition is calculated. (2) according to the transmission principle of the key mechanism of SD7V16, the mathematical model is established, and the kinematic analysis of the key mechanism is carried out. The formulas of displacement, velocity and acceleration of piston are obtained, and the geometric algorithm of displacement is obtained. The movement accuracy of piston and its influence on displacement are analyzed by introducing the dimension deviation of key parts. The virtual prototype simulation of the key mechanism of SD7V16 is carried out by Adams. The simulation results show that the theory based on the mathematical model is feasible, and the calculation results are correct. According to the functional relationship between the displacement and the refrigerating capacity, the functional relationship between the refrigerating capacity and the key size is obtained. The partial differential equation between the refrigerating capacity deviation 螖 Q _ 0 and the dimension deviation of the key parts of the compressor is solved when the maximum inclined angle is 24 掳, which is regarded as the performance constraint for the optimization of the dimensional tolerance of the key parts. Finally, the economic machining precision constraint of dimension tolerance of key parts is introduced, and the investigation data are combined. Taking the sum of the cost of mass loss and the cost of machining as the objective function, the tolerance optimization model is solved based on MATLAB genetic algorithm.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.851

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