| 摘要 |
1523600 Control of DC motors STILL GmbH 14 Oct 1975 [17 Oct 1974] 41928/75 Heading H2J A D.C. motor (not shown) is controlled by a transistor or thyristor (not shown) providing pulses whose repetition frequency or duration is determined by the setting of a member 1 providing an input signal to a voltage/frequency converter 11, the signal also being applied to a comparator 2 whose second input is a reference signal from voltage divider 12, 13 whereby, at start-up when a direction switch 7 is moved to select contactor coil 5 or 6 according to a desired direction of motor rotation, the selected coil is energized by switch-on of a transistor 4 when the signal from member 1 reaches the reference signal value to cause comparator 2 to produce an output signal, subsequent further increase of the signal from member I causing the converter 11 to initiate the supply of pulses to the motor. The signal to transistor 4 may pass through a logic gate 3 receiving additional input signals, e.g. motor temperature, whereby the transistor is switched off to de-energize coil 5 or 6 if the temperature exceeds a predetermined limit. |
