| 摘要 |
A pump control controls the rate at which liquid is pumped through a tube. The pump has a variable speed shaft with a roller thereon engaged with the tube between the tube inlet the tube outlet for pumping liquid from a supply toward the tube outlet when the pump shaft operates. A first sensor senses liquid at a first location in the tube and a second sensor senses liquid at a second location in the tube between the first location and the tube outlet. A vibratory beam is coupled with the tube between the first location and the second location. An electric circuit transfers energy to a magnet on the beam and induces a natural response in the beam and the tube. A microprocessor executes a software program and a) monitors operation of the pump when liquid is pumped into the tube between the sensors, b) measures the frequency of the induced natural response of the tube and liquid contained therein, c) computes the mass of liquid in the tube between the sensors, d) computes a pump rate as a function of the pump operation required to fill the tube between the sensors and the measured mass of liquid pumped into the tube and a desired flow rate, and e) operates the pump at the computed rate.
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