Conversion of the Stroke of Piston Rod in Hydraulic Actuators into an Electrical Signal

油压致动器中活塞杆的放出长度需要被远程感知，例如通过电信号的大小，以便命令致动器，从而远程或自动操作液压机系统。这项研究的目的是找到一种适当的方法将长度转换成电信号。由于活塞杆是由合金钢制成的，在活塞杆表面植入一系列磁性刻度，使活塞杆成为一种磁性刻度棒。在气缸口的衣领处镶嵌了一组磁电传感器，产生一系列可计数的电压脉冲作为读出的距离信号。组成每个梯度线的单个磁化强度必须非常局部而不模糊，以建立清晰的梯度。每个刻度的间隔不能超过40mm。如果它被设置得比40毫米更近，剩余磁化就会因为即将到来的毕业植入而变得模糊。传感器组件的输出被转换成双相方力波，其每一次跃迁都被检测到，并且一个特殊的逻辑电路执行四分之一的分辨率距离来确定由磁刻度测量的位移。双相信号波还产生活塞杆运动的方向信号，通过该方向信号可以切换计数方式为向上计数或向下计数。

The let out length of the piston rod in oil hydraulic actuators is desired to be perceived remotely, for instance by means of a magnitude of electrical signal, in order to command the actuator, and consequently to operate the hydraulic machine system remotely or automatically.This research was aimed at finding out an adequate way to convert the length into an electrical signal. Since the piston rods are made of an alloy steel, a series of magnetic graduations is implanted onto the rod surface in order to make the rod as a kind of magnetic scale stick. An assembly of magnetogalvanic sensors which has been inlaid at collar of the cylinder mouth, produces a series of countable electric voltage pulses as the read out of distance signal. The individual magnetization which composes the each graduation line must be very local without blurring to establish a clear graduations.The interval of each graduations could not be more closer than 40 mm. If it was set more closer than 40 mm, the residual magnetization was forced to be vague by the forthcoming implanting of the graduations. The output of sensor assembly is converted into double phase square voltage waves, whose every transition is detected, and a special logic circuitry performs one-fourth resolution distance in determination of the displacement measurement from the magnetic graduations.The double phase signal waves produce also the direction signal of the motion of piston rod, by which the counting mode can be switched as to count up or to count down.