SENSOR OF DOWNHOLE FLOWMETER Russian patent published in 1994 - IPC

FIELD: well drilling. SUBSTANCE: sensor has permanent magnet 11 eccentrically installed on shaft of impeller 5. Permanent magnet periodically makes and breaks contacts of reed relay 13 fixed in body 1. Ferromagnetic ring is installed in body coaxial to impeller at the level of mass center of permanent magnet to reduce eccentricity of permanent magnet. Ring has through slot in which reed relay in installed parallel to instrument axis. EFFECT: higher efficiency. 2 dwg