US PATENT SUBCLASS 417 / 56
DRILLED WELL FREE PISTON-TYPE PUMP

Current as of: June, 1999
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417 /   HD   PUMPS

56DRILLED WELL FREE PISTON-TYPE PUMP {4}
57  DF  .~> Having condition or position responsive control of pump discharge flow path
58  DF  .~> Having condition or position responsive control of motive fluid supply
59  DF  .~> Radially expansible piston portion controls pump and motor chamber intercommunication
60  DF  .~> Mechanically actuated valve carried by piston

DEFINITION

Classification: 417/56

(under the class definition) Apparatus in which the pump has a piston which reciprocates within an elongated cylinder of uniform cross-sectional dimensions which is adapted to be positioned within a drilled well, said piston serving to separate the cylinder into respective motor and pump chambers, means providing either a restricted or a controlled flow path which provides communication between the pump and motor chambers (i.e., between opposite sides of the piston), the induction of at least a portion of the fluid to be pumped flowing serially through the motor chamber, said restricted or controlled flow path, and thence into said pump chamber; motive fluid being subsequently applied to said motor chamber to drive said piston on an eduction stroke.

(1) Note. The motive fluid under this definition may be derived either from the well itself or from an external source.

(2) Note. This subclass and those indented hereunder are intended to include the subcombination of a valved or radially expansible piston for performing a valving function which is disclosed as having utility in the apparatus defined herein.