超磁致伸缩伺服阀用电-机转换器传热及热误差分析

Modeling of Heat Transfer and Displacement Error from Heat of Giant Magnetostrictive Actuator Applied in Servovalve

提出了一种超磁致伸缩伺服阀用超磁致伸缩电-机转换器的结构并阐述了其工作原理,此电-机转换器采用了油液冷却和反向补偿法来抑制因热产生的位移输出。为分析温升对超磁致伸缩电-机转换器控制精度的影响,基于导热和对流传热理论建立了其传热模型,给出了稳态时超磁致伸缩棒上的温度和热补偿装置上的温度,分析了冷却油液流速对稳态温度的影响,并采用温度场数值模拟的方法对仿真结果进行了验证。分析结果表明,当控制电流为额定值1 A时,若超磁致伸缩棒和控制线圈间油液速度大于0.1 m/s,热补偿装置和超磁致伸缩棒的温度在20.3℃附近且温差在0.2℃以下。由超磁致伸缩棒和热补偿装置上的温度,进一步推导出了超磁致伸缩电-机转换器因热而产生的误差位移。通过仿真分析得出,在超磁致伸缩棒和控制线圈间油液速度等于0.1 m/s时,棒和外壳温度接近且温升不大,热误差位移不大于0.1μm。

The performance of servovalve driven by giant magnetostrictive actuator is seriously affected by temperature rising. In order to reduce the error from temperature rising, a giant magnetostrictive actuator applied in servovalve was presented and its working principle was introduced. The output displacement error of actuator from rising of temperature was controlled by cooling and compensating. In order to analyze the influence of heat on the accuracy of giant magnetostrictive actuator, heat transfer model was deduced from the theory of heat conduction and transversal heat transfer, the steady-state temperature on giant magnetostrictive rod and shell were given, and the simulation results were verified by numerical simulation. The results showed that when the velocity of oil surrounding giant magnetostrictive rod was more than 0. 1 m/s at control current of 1 A, temperature of giant magnetostrictive rod and shell was about 20.3℃, the difference in temperature can be limited below 0.2℃, and temperature rise of giant magnetostrictive actuator was small. The displacement error from heat was derived based on the model described the temperature on giant magnetostrictive rod and shell. The simulation results showed that when the velocity of oil surrounding giant magnetostrictive rod was more than 0. 1 m/s, the output displacement from heat was less than 0. 1 μm.