DOWNHOLE SUCKER-ROD PUMP Russian patent published in 2006 - IPC F04B47/00 

FIELD: sucker-rod pumps, particularly adapted for formation fluid production.

SUBSTANCE: sucker-rod pump comprises cylinder with suction valve, hollow piston with injection valve provided with gas chambers communicated with cylinder. The gas chambers are arranged in central cylinder part and spaced a distance equal to hollow piston length L from upper and lower ends thereof. Active chamber volume obeys the following condition: F_k(l₁+l₂+...+l_n)≤F_p·H, where F_k is chamber cross-sectional area, l₁-l_n are opened gas chamber space heights, F_p is plunger cross-section defined by outer diameter, H is distance between extreme upper and lower positions of hollow plunger. Gas chambers are made as pockets, which are shaped as rings or ring sections located one upon another or in staggered order.

EFFECT: extended functional capabilities.

3 cl, 1 dwg