Patent ID: 6409476
Filing Date: 2002-06-25
Classification: E21B,F04B

Abstract:
A dynamometer readout apparatus for a pumpjack with a walking beam, said walking beam being pivotally moveable in a first pivotal direction and in an opposite second pivotal direction, said walking beam changing pivotal direction twice during each pumping cycle for pumping a well, said apparatus comprising:an encoder component pivotally secured to said walking beam, said encoder component having a plurality of spaced apart slots disposed therein, said encoder being biased to remain at a reference orientation relative to said walking beam; first and second light emitters with corresponding first and second light detectors respectively aligned on opposing sides of said encoder component, said first and second light emitters and corresponding first and second light detectors being fixed to said walking beam for angular movement in said first and second pivotal directions with respect to said reference orientation of said encoder component, said first and second light emitters and corresponding first and second light detectors being mounted with a spacing different than said spaced apart slots of said encoder component to thereby produce a first sequence of signals for movement of said walking beam in said first pivotal direction and a second sequence of signals for movement of said walking beam in said second pivotal direction; a load sensor mounted to detect loading corresponding to said pumping cycle for producing an electrical load signal; and a processor electrically connected to said first and second light detectors to receive said first sequence of signals and said second sequence of signals, said processor analyzing said first sequence of signals and said second sequence of signals to detect a change in direction from said first pivotal direction of said walking beam to said second pivotal direction of said walking beam, said processor using said change in direction to control initiation of sampling of said electrical load signal.