| 摘要 |
PURPOSE:To detect the liquid-level height of a content liquid precisely when a tank is nearly emptied by using an ultrasonic oscillation type detection part, equipping the detection part in a case whose bottom surface is so formed that the case is mounted stably on the bottom surface of a moving tank, and thus constituting a detector body. CONSTITUTION:The content liquid in a moving tank is sucked through a pump and during this period, the diaphragm 9a of a detecting element 9 is in the liquid, so it does not oscillates and a transistor (TR) switching circuit 9d is not operated, so that no switching output is generated. Then when the content liquid decreases and the tank is nearly emptied to expose the diaphragm 9a to air, the diaphragm 9a starts oscillation to obtain variation in the output voltage of an amplifier, and the circuit 9d is operated to output a switching output. Consequently, the pump for sucking the content liquid of the moving tank is switched off. Thus, before the content liquid is discharged completely, the invented level switch detects that to stop the operation of the pump, and the occurrence of cavitation is avoided. |
