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Modulated voltage for a solenoid valve

  • US 6,493,204 B1
  • Filed: 08/30/1999
  • Issued: 12/10/2002
  • Est. Priority Date: 07/09/1999
  • Status: Expired due to Term
First Claim
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1. A control unit for a solenoid valve comprising:

  • a power supply;

    a solenoid valve coil have a first end and a second end, said first end of said solenoid valve coil being connected to said power supply;

    an electronic switch having a first terminal connected to said second end of solenoid valve coil, said electronic switch also having a second terminal connected to ground, said electronic switch operable for controlling the flow of an electric current through said solenoid valve coil, said switch further having a control port and being responsive to a control signal applied to said control port to transition between conducting and non-conducting stages;

    a signal generator included within a microprocessor, said microprocessor having an output control port connected to said control port of said electronic switch, said signal generator operative to generate a control signal at said microprocessor output control port, said control signal being a pulse width modulated signal having a variable duty cycle and a constant frequency and said signal generator being operable to generate a first control signal with a predetermined first constant duty cycle sufficient to begin to move an armature of an associated solenoid valve and then to generate a second control signal with a second predetermined constant duty cycle that is less than said first duty cycle and is sufficient to maintain the associated solenoid valve armature in a desired position within the valve; and

    a single voltage divider connected across said electronic switch, said voltage divider including a center tap connected to a feedback port of said microprocessor, said microprocessor being responsive to a voltage appearing at said center tap to confirm the operation of said electronic switch.

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