Abstract: A controller for controlling the pump unit of an oil well includes a sensor having a first and second probe for placement in the flow of oil from the well bore. Each of the probes contains a heater. A constant power source is selectively connected to one of the heaters. Each of the probes also includes a linear RTD at each of their tips respectively for generating a signal indicative of the temperature measured at each of the first and second probes. A control unit receives signals from the RTD's and determines a flow rate therefrom. A pump control signal is generated in response to the flow rate, wherein the pump control signal continuously varies a predetermined parameter for controlling the flow rate of a pumping unit during operation of the pumping unit.

Abstract: A controller for controlling the pump unit of an oil well includes a sensor having a first and second probe for placement in the flow of oil from the well bore. Each of the probes contains a heater. A constant power source is selectively connected to one of the heaters. Each of the probes also include a linear RTD at each of their tips respectively for generating a signal indicative of the temperature measured at each of the first and second probes. A control unit receives signals from the RTD's and determines a flow rate therefrom. A pump control signal is generated in response to the flow rate, wherein pump control signal continuously varies a predetermined parameter of a pumping unit during operation of the pumping unit.

Abstract: A controller for controlling the pump unit of an oil well includes a sensor having a first and second probe for placement in the flow of oil from the well bore. Each of the probes contains a heater. A constant power source is selectively connected to one of the heaters. Each of the probes also include a linear RTD at each of their tips respectively for generating a signal indicative of the temperature measured at each of the first and second probes. A control unit receives signals from the RTD's and determines a flow rate therefrom. A pump control signal is generated in response to the flow rate, wherein pump control signal continuously varies a predetermined parameter of a pumping unit during operation of the pumping unit.

Abstract: A controller for controlling the pumping unit for an oil well comprises a housing having a first and a second tip for placement in a flow of oil between the wellbore to holding tanks; means for generating a substantially constant power; a constant power heater in the first tip connected to the means for generating, for radiating a substantially constant heat; means for determining the temperature at each the first and second tips and for generating a digital signal indicative of the temperature of the first and second tips; supervising means for controlling the means for determining, processing the digital signal for determining a rolling average signal, and generating a control signal therefrom which is independent of ambient temperature of the oil flow; and means for switching the pumping unit on or off, according to the control signal. The controller further comprises means for calibrating the means for determining. The constant power heater is preferably a FET connected in series with a resistor.