| 摘要 |
1,223,822. Control of D.C. motors. CLARK EQUIPMENT CO. 29 Jan., 1969 [12 Feb., 1968], No. 4846/69. Heading H2J. [Also in Division G3] In an automatic speed control system for an electrically powered vehicle a speed reference signal 100 switchable between a high and a low value is applied to a comparator amplifier 112 by way of an integrating network 106, 107 so as to limit the acceleration during starting and stopping of the vehicle. The switching system including relays and reed switches operated by magnets at a home and remote station (Figs. 1, 3, riot shown) is contrived such that upon depression of a start button (30) a positive control voltage 101 is connected to the network and the rising voltage across capacitor 107 is applied together with a vehicle speed signal from a tachogenerator 116 to the amplifier 112. The output of the amplifier supplies the field winding 124 of a generator 120 supplying the D.C. drive motor 130; an A.C. motor 128 drives the generator. As the vehicle approaches the remote station a reed switch reduces the control voltage by a potential divider 104, 105 to slow the vehicle and a short while later a relay disconnects the control voltage and substitutes the output of a transducer 110 sensing the vehicle position so as to bring the vehicle to a halt at the remote station (as described in Specification 1,109,220). After a period necessary to unload the vehicle the negative control voltage 103 is connected to the network and the vehicle is driven back to the home station. As the vehicle approaches the home station speed is reduced and the vehicle positioned as before and then after a final delay the control voltage is disconnected until the push-button is operated again to restart the cycle. The system is suitable for use in a. stacking apparatus as described in Specification 1,178,603. |
