JPS5737213A - Detector for karman vortex amount - Google Patents

Abstract

PURPOSE:To provide with a perfect gas-proofness, to improve a noise resistance, and to enable to perform a high-precise measurement, by a method wherein a device is constituted such that the number of ka rma n vortexes produced is measured by means of a photosignal without the use of an electric signal as input and output of a detector. CONSTITUTION:Through the flow of a fluid in the direction of an arrow mark 12 at a constant velocity, ka rma n vortexes 22 are produced alternately at a right and a left side in a manner to keep a constant distance h between the 2 rows and a constant pitch l. For example, a flow of a fluid is created in a direction of an arrow mark 23 in a pressure guide hole 13 through a differential pressure before a vortex 22' is produced, and a small ball 14 moves against an absorbing force of a magnet 15. A 13A reflects a projection light 18 and transfers a reflection light 19 to the outside of a detector. Then, when the vortex 22' is produced, the differential pressure is brought into a null condition, and the small ball 14 returns to a position shown in a drawing through the absorption force of the magnet 15. When the small ball 14 is located in a position shown in the Fig., the projection light 18 does not reach the 13A, and the reflection light 19 is not produced, or a light path is shut off. Then, the small ball 14 moves in the direction of an arrow mark 24 for a given period of time until a vortex is produced at an opposite side, and transfers the reflection light 19. This permits the measurement of the number of generating times per second of the reflection light 19 as a frequency.