动压反馈伺服阀时间常数计算方法(英文)

Time constant of a hydraulic servo valve with dynamic pressure feedback

动压反馈技术应用于喷嘴挡板伺服阀中可以显著改善其响应特性。在伺服阀中实现动压反馈最可靠的方法是在其中增加一个动压反馈装置。但根据传统设计方法,加工出的动压反馈伺服阀中的关键变量时间常数通常与设计值相差很大,主要是因为传统设计方法错误地将动压反馈装置中喷嘴出口处的油液认为是紊流。根据理论推导和实验研究,证实了喷嘴出油其实为层流;进而对动压反馈伺服阀时间常数的计算方法重新进行了梳理,该方法对于动压反馈伺服阀的设计具有重要意义。

Dynamic pressure feedback （DPF） technology is usually used in a hydraulic servo system to improve its response characteristics. The most reliable way to realize the feedback is to integrate a mechanical DPF device in a flow control servo valve. However, as a key parameter, the time constant is usually big different between the desired and actual valve if the valve has been designed by traditional method. We analyze this reason which is mainly caused by the wrong assumption that oil jetting from feedback nozzles is in the turbulent flow region. Based on the theoretical analysis and experimental tests, it has been confirmed that the fluid flow is indeed in laminar flow region. Therefore, a new method to evaluate the time constant could be obtained, which will be very useful for the design of a DPF device.