| 摘要 |
PURPOSE:To obtain accurate proportional control by setting the rectangular voltage frequency to a predetermined small value, when average voltage applied is small, and increasing the rectangular voltage frequency, when the average voltage applied is large. CONSTITUTION:When a rectangular signal indicating a relatively small opening degree is transmitted from opening degree indicating means 1 to rectangular signal generating means, a reference oscillation frequency signal 11 is transmitted from oscillating means 10 to the rectangular signal generating means, and in a vibrating condition, a valve member is moved to a position corresponding to the indicated opening degree. When a rectangular signal indicating a relatively large opening degree is transmitted from the opening degree indicating means 1 to the rectangular signal generating means, frequency increasing means is actuated to increase the oscillation frequency of the oscillating means 10 in correspondence to the opening degree indicating signal 1, permitting movement with vibration restricted.
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