RELIEF VALVE OF DOWNHOLE MOTOR Russian patent published in 2008 - IPC E21B4/02 E21B21/10 

FIELD: mining.

SUBSTANCE: invention relates to drilling technique and can be used as a valve unit for screw-type downhole motors in a drilling pipe string for connection or disconnection of the internal cavity of drilling pipes and the annular space following the pre-set technological sequence. The valve contains a case, a valve pair provided with a sliding ring, the seat mounted in the case and a hollow plunger accommodated inside the seat, with radial holes in them, a spring mounted on the hollow plunger and gaskets. The valve pair is of the slide type, in which the diameter of the flowing channel is 0.10-0.12 of the length of the hollow plunger and the area of all radial overflow holes of the hollow plunger is equal to the area of flow channel in the cross-section of the hollow plunger. The hollow plunger is of cylindrical form with the sliding ring and the circular collar, located in the lower part of the sliding ring and spring-loaded up to the stop by the upper end of the circular collar to the lower end of the seat. Radial overflow holes of the hollow plunger and the radial holes in the seat and in the case are located at the same level and the spring is mounted between the case stop and the lower end of the circular collar of the hollow plunger.

EFFECT: high reliability of operation of the valve in the process of drilling, excluding spill of flush fluid during lifting the drilling pipe string and filling the internal cavity of pipes during dropping.

2 dwg