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Driver device for a duty solenoid valve

  • US 5,202,813 A
  • Filed: 11/21/1990
  • Issued: 04/13/1993
  • Est. Priority Date: 11/24/1989
  • Status: Expired due to Term
First Claim
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1. A driver device for a duty solenoid valve which controls fluid pressure by adjusting a duty ratio of an excitation of a solenoid coil, said driver device comprising:

  • first driver means for controlling a current level of an excitation current through said solenoid coil, in response to a duty ratio of a first pulse signal;

    second driver means for turning on and off an excitation current flowing through said solenoid coil, in response to a second pulse signal having a substantially longer period than said first pulse signal;

    current detector means for detecting a level of the excitation current flowing through said solenoid coil;

    first pulse width modulation signal generating means for generating, in response to the level of the excitation current detected by said current detector means, said first pulse signal having a duty ratio corresponding to a target excitation current level, said first pulse width modulation signal generating means including means for storing a reference value corresponding to the duty ratio of said first pulse signal and means for comparing said reference value to a value contained in a counter means wherein said first pulse signal is output based upon said comparison; and

    second pulse width modulation signal generating means for generating said second pulse signal having a duty ratio corresponding to a target fluid pressure of the duty solenoid valve;

    wherein said first and second pulse width modulation signal generating means are comprised in a microcomputer.

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