CIRCULATING VALVE Russian patent published in 2019 - IPC E21B34/06 F16K3/26 

FIELD: valves.

SUBSTANCE: invention relates to valve devices. Valve comprises upper and lower adapters, housing with radial hydraulic channels, sealing elements and hollow piston having a spring. Piston has a recess for its spring provided with a clamping element. Hydraulic chamber located between piston and inner surface of housing is communicated with radial hydraulic channels in housing. Spring with clamping element is located between end of upper adapter and ledge of piston pressed to end of lower adapter due to additional ledge made in piston from inner side. In the piston, on the outer side there is an annular recess arranged between the sealing elements forming a hydraulic chamber communicating with the radial hydraulic channels in the housing. In upper part of lower adapter there are radial holes, which in closed state of valve are closed by piston. Diameter of upper part of lower adapter on outer side is smaller than in lower part, forming, when piston moves up, additional hydraulic chamber connecting through radial hydraulic channels in housing and through radial holes in lower adapter in-tube and annular space. On inner lower part of upper adapter cylindrical recess is made, which forms shoulder, limiting piston movement upwards.

EFFECT: technical result consists in improvement of reliability of valve.

4 cl, 2 dwg