OVERFLOW CHECK VALVE Russian patent published in 2009 - IPC E21B4/00 E21B34/06 

FIELD: oil and gas production.

SUBSTANCE: overflow check valve is related to the field of drilling and geological survey wells and may be used in drilling with screw downhole motor. It comprises valve body with subs, inside of which there is a plunger body and a spring-loaded hollow plunger, which is plugged at the bottom. Plunger comprises upper radial holes and is arranged in upper and lower parts, which are connected to each other by means of joint elements to create lower radial holes of plunger between them. Bushing with circular bore is located at the level of plunger holes in its lower position. Cavity of upper sub is hydraulically connected in upper position of plunger with plunger holes, radial holes of plunger body and radial holes of valve body, in lower position of plunger - with its lower radial holes and cavity of lower sub. Bush is made of hard baked alloy VK-8.

EFFECT: improved conditions for passage of flushing fluid, reduced hydraulic resistance in straightened channels.

3 cl, 2 dwg