Patrick W Mcfadden

US Patent:

D4347501, Dec 5, 2000

Filed:

May 24, 2000

Appl. No.:

D/123730

Inventors:

Dwaine A. Childers - Chillicothe OH
Patrick A. McFadden - Bainbridge OH

International Classification:

1401

US Classification:

D14204

US Patent:

44039190, Sep 13, 1983

Filed:

Sep 30, 1981

Appl. No.:

6/306953

Inventors:

George E. Stanton - Orient OH
Patrick A. McFadden - Columbus OH

Assignee:

Njuack Oil Pump Corporation - Columbus OH

International Classification:

F04B 4708

US Classification:

417 53

Abstract:

Apparatus for pumping a liquid from a well comprises a drive unit on the surface, a well-bottom pump unit, two supply lines interconnecting the drive unit and the pump unit and a liquid discharge line extending from the pump unit to the surface for discharge of liquid. The pump unit has a drive piston which is reciprocated within a drive cylinder by applying pressure alternately by means of a changeover valve to the two supply lines. The drive piston drives a double acting driven piston which pumps oil from a well. The changeover valve is controlled by a logic unit which receives signals from sensors measuring the pressure and/or flow rate in a return line. The time necessary to carry out complete strokes of the drive piston is determined by measuring the change in pressure and/or flow rate in a return line as the drive piston reaches the extremity of its motion and a logic unit then calculates upstroke and downstroke periods dependent upon the intervals necessary to carry out complete strokes of the drive piston. The logic unit then effects repeated pumping cycles, holding the changeover valve in a first position for a first predetermined period and in a second position for a second predetermined period.