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Sprayer control system

  • US 4,392,611 A
  • Filed: 05/15/1981
  • Issued: 07/12/1983
  • Est. Priority Date: 05/15/1981
  • Status: Expired due to Term
First Claim
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1. An automatic control system for a vehicular liquid sprayer which pumps liquid at a desired pressure to a plurality of nozzles which dispense liquid at a desired volume per unit area application rate, said application rate being a function of predetermined properties of said vehicular liquid sprayer and of the liquid, said control system comprising:

  • pressure sensing means for sensing the instantaneous pressure of the liquid supplied to said nozzles and for producing a corresponding pressure electrical signal, means for measuring the ground speed of said vehicular liquid sprayer and for producing a corresponding ground speed electrical signal, control circuit means for receiving said pressure signal and said ground speed signal, operator accessible control means for delivering to said control circuit means input electrical signals corresponding to a desired application rate, to the number of nozzles associated with said vehicular liquid sprayer and to the nozzle spacing, said control circuit means being responsive to said pressure signal, said ground speed signal and said input signals for calculating a desired pressure of the liquid supplied to said nozzles necessary to achieve said desired application rate and for calculating the difference between said desired pressure and said instantaneous pressure and producing a first output control signal of a magnitude corresponding to the difference between said desired pressure and said instantaneous pressure and a second output control signal corresponding to the sign of said difference, duty cycle control means for converting said first output control signal to a cyclical control signal of a fixed period whose duty cycle varies in proportion to the magnitude of said first output control signal and pressure control means responsive to said cyclical control signal and to said second output control signal for varying said instantaneous pressure in the amount and direction necessary to equal said desired pressure to thereby achieve and thereafter maintain said desired application rate.

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