OVERFLOW VALVE Russian patent published in 1996 - IPC

FIELD: drilling equipment; over-flow valve of bottom-hole motors, applicable for communication of the internal hollow of bottom-hole motor with drill string-borehole annulus in round trip operations. SUBSTANCE: overflow valve has hollow body with radial channels, shutoff member moving longitudinally, seat with bypass channels and flow-through bushing. The latter is secured to seat. Shutoff member is located between flow-through bushing and body and made in form of cylindrical bushing. Attached to cylindrical bushing of shutoff member is two-collar cup. Seat is installed above shutoff member. Weighting rings are installed on lower part of shutoff member. Diaphragm is installed in the annular gap between flow-through bushing and shutoff member. cup collar overlaps the seat bypass channels with the shutoff member being in the extreme upper position. EFFECT: simplified design, higher reliability and efficiency of overflow of fluid in lifting the drill string for one stand, higher efficiency of valve operation due to change of hydraulic resistance on the shutoff member. 3 cl, 3 dwg