Ultrasonic compact sensor device for detecting pistons in hydraulic systems has ultrasonic sensor, fastened at cylinder from outside whereby several ultrasonic impulses are produced by ultrasonic sensor after electronic excitation

摘要

The device has an ultrasonic sensor, fastened at the cylinder from outside, and an electronic control and evaluation unit. After the electronic excitation, several ultrasonic impulses, having resonant frequency from 250 KHz to 4 MHz, are produced by the ultrasonic sensor, which propagate by the cylinder wall and the medium in it and are reflected by the opposite cylinders. The evaluation unit has an adjustable amplifier for the reflected signals and a comparator for comparison with the set threshold value. Surface volume of two expected ranges are constantly evaluated, whose time gap depends upon the ultrasonic impulses from the cylinder diameter and is set in a fixed manner. The overall maximum time period amounts to 5000 mu s and is adjustable in different steps. Ultrasonic signal forms are utilized for evaluating the changing characteristics, which are formed depending upon the condition and are compared with each other.