RETURN VALVE FOR DRILLING STRING Russian patent published in 2017 - IPC E21B34/10 E21B21/10 F16K15/06 

FIELD: mining engineering.

SUBSTANCE: return valve contains a monolithic body with passage channel for flow fluid including a front and rear bushings, located between the side walls, end-to-side window, forming a side through window, a pin located between the side walls near the rear bushing with a central hole, a longitudinal groove and ribs, located between the pin and the side walls. In this case, the body front bushing has a valve seat and a collar seat, seals for sealing the body relative to the drill string. The front bushing contains a valve module, including a valve with a working face contacting tightly with the valve seat in the front body bushing. At that, the central part of the valve front wall has a spherical surface and also includes a rod connected to the valve, a pressure bushing, an elastomer collar with flexible annular edge and a flat part of a single structure. The flexible circular edge of the collar is in contact with the collar seat in the body front bushing, and the flat part of the collar is located between the rear face of the valve and the pressure bushing, a spring creating an offset force of the valve module in tight position, which can overcome the pressure of the flow liquid acting in the opposite direction to the spring and guide sleeve for valve rod mounted in the pin hole. The distance H between the ends of the valve and the pressure bushing forming a slit cavity for accommodating the flat part of the collar and the thickness T of the collar flat part contacting the collar seat in the body front bushing are related by ratio H=(0.65÷0.85) T. The body side walls at the conjugation of body with ribs on the length of the centering bushing for the rod have a cross-sectional area of 65% to 75% of the cross-sectional area of the body side walls. The return valve comprises a deflector with radially arranged ribs installed in the grooves on the end of the body front bushing directed against the fluid flow.

EFFECT: increased service life of return valve for the drill string.

4 cl, 9 dwg