DOWNHOLE VALVE UNIT Russian patent published in 2012 - IPC E21B34/08 

FIELD: oil and gas production.

SUBSTANCE: device includes housing with annular projection on the inner surface, spool movable in axial direction that has an upper tail piece of smaller diameter in the upper part of which there are drain openings and restraining shoulder. The spool is equipped with through axial channel where there is a non-return valve. Annular starting chamber is connected to axial channel of the spool by holes in the lower part of upper shank. In the lower part of the spool there is a lower shank of smaller diameter, and in the upper part of the upper shank of the spool there is a safety valve in axial channel. At the upper stage of axially moving two-diameter piston there is a hollow cylinder, in the walls of which there located are collets and drain openings. Note that hollow cylinder is tightly connected and combined by its outer side with the piston upper step and as for the inner part the upper step of axially moving two-diameter piston forms an annular setting projection. Restraining shoulder is made with the possibility of tight setting of upper step of axially moving two-diameter piston on the annular setting projection and collets are installed with the possibility of interaction with housing annular projection and restraining shoulder.

EFFECT: increase of process operations effectiveness and device operation reliability.

4 cl, 3 dwg