| 摘要 |
1,236,116. Automatic speed control. HITACHI Ltd. Sept. 12, 1969 [Sept. 16, 1968], No. 45227/69. Heading G3R. A speed control system for lifts comprises a device SO providing a voltage corresponding to a pattern speed irrespective of the lift-position during the acceleration period, the said voltage being reduced in a stepped manner with the aid of a position detector POS operable when the lift arrives at any one of a number of pre-set deceleration-points. A comparator CP, which is saturable in the positive and negative directions, is connected to an integrator I providing negative feedback to the comparator. The integrated output is also supplied to a speed control system for the lift. A changeover relay RY1 passes the command signal alternatively to the comparator CP during the acceleration period, and to an amplifier AP1 during the deceleration period. The amplifier AP1 is connected to a tachometer generator PG, and supplies a speedcorrecting signal to the integrator I whose output is applied through amplifier AP2 to the field winding of a Ward Leonard generator G associated with the lift-motor M. In a modification, a clamping circuit is connected to the output of the amplifier AP1 to provide a dead band effect, Fig. 2 (not shown). The amplifier AP1 may have a saturation characteristic to limit the rate of deceleration, Fig. 4 (not shown).
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