Pump stand with improved pump control

Abstract

Integrated, stand-alone, multiple-purpose pump stands are provided for controlled pumping of different liquids from a stand-mounted tank to a downstream use location, e.g., a seed treating device. The pump stands are equipped with an operating assembly including a liquid tank, a powered pump, a liquid flow line equipped with a flow meter from the tank and pump to the use location, and a programmable digital control device. During operation, the control device serves to approach and maintain the flow rate from the pump stand at or about a desired setpoint flow rate.

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         12 . An integrated pump stand operable to deliver liquid at a controlled flow rate, comprising:
 a supporting frame assembly;   an operating assembly supported by the frame assembly and including—
 a tank operable to hold a liquid to be delivered; 
 a powered pump; 
 a flow line operably coupled with said tank and pump for delivery of liquid from the tank; 
 a flow meter operably attached to said flow line to determine the flow rate of liquid through said flow line; and 
 a controller device operably coupled with said pump and flow meter in order to deliver liquid from said flow line at or about a preselected setpoint flow rate. 
   
     
     
         13 . The pump stand of  claim 12 , said controller device being a digital device programmed to continually monitor and adjust the flow rate of said liquid by control of said pump, to maintain the liquid flow rate at or about said setpoint flow rate. 
     
     
         14 . The pump stand of  claim 12 , said controller device being a digital device programmed to:
 (a) control the operation of said powered pump so as to pump the liquid at a flow rate at or about said setpoint flow rate, by periodically comparing the determined flow rate of the liquid from said source with said setpoint flow rate, and:
 (i) if the difference between the determined flow rate and the setpoint flow rate is at or above a first predetermined magnitude, operating said pump so as to alter the operation of the pump at a relatively high aggressive first correction rate, so that the determined flow rate approaches said setpoint flow rate at the aggressive first correction rate; 
 (ii) if the difference between the determined flow rate and the setpoint flow rate is at or above a second predetermined magnitude but below said first predetermined magnitude, operating said pump so as to alter the operation of the pump at a relatively low moderate second correction rate lower than said first correction rate, so that the determined flow rate approaches said setpoint flow rate at the moderate second correction rate; and 
 (iii) continuing said controlling step (a)(i) and (a)(ii) throughout the flow of liquid from said liquid source. 
   
     
     
         15 . The pump stand of  claim 14 , said digital device also programmed to control the operation of said powered pump such that if the difference between the determined flow rate and the setpoint flow rate is at or above a third predetermined magnitude but below said second predetermined magnitude, and to operate said pump so as to alter the operation of the pump at a relatively lower conservative third correction rate lower than said second correction rate, so that the determined flow rate approaches said setpoint flow rate at the conservative third correction rate. 
     
     
         16 . The pump stand of  claim 12 , including a human operator interface operably coupled with said controller device permitting entry of said setpoint flow rate. 
     
     
         17 . The pump stand of  claim 12 , including calibration apparatus operable to determine the actual flow rate of said liquid. 
     
     
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         19 . The pump stand of  claim 12 , said controller device having memory operable to store a plurality of flow rate correction factors for a corresponding plurality of different liquids. 
     
     
         20 . The pump stand of  claim 12 , said controller device being programmable and operable to apply a feedback control loop according to a tiered control scheme. 
     
     
         21 . The pump stand of  claim 20 , said controller programmed to employ a multi-tiered proportional-integral-derivative (PID) control loop. 
     
     
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         23 . The pump stand of  claim 12 , said tank operable to hold a seed coating liquid.