| 摘要 |
1, 083, 722. Automatic speed and power control. CATERPILLAR TRACTOR CO. Jan. 25, 1965 [Feb. 13, 1964], No.3126/65. Heading G3R. [Also in Division H2] In a constant-power diesel-electric system for supplying traction motors, a control field winding 42 of the generator is energized in accordance with the deviation of the engine speed from a set value, the field winding being connected in series with a transistor 39. When manual controller 19 is adjusted to supply more fuel to the engine, rotor 54 of transducer 46 is moved to increase the voltage across secondary 57 whereby transistor 47 is biased to decrease the energization of winding 42. The load on the engine decreases, so that its speed rises to increase the voltage developed across resistor 52 from tachometer 24. This causes the transistor 47 to pass more current, so increasing the excitation of winding 42. When controller 19 is adjusted for decreased power, the energization of field winding 42 is increased so applying more load to the engine which decelerates. When the desired operating speed is attained, the current through winding 42 will reach a steady value. An R. C.-circuit 61, 63, controls the rate of unloading of the engine during acceleration, and affords a quick response to an initial call for acceleration. When the wheelspeed becomes excessive, a tachometer 66 develops sufficient voltage to break down Zener diode 72. This increases the potential at emitter 49 to decrease the excitation of winding 42 whereby the motor-power is decreased. For dynamic braking operation, switch 76, 76', is changed over so that braking resistor 78 is now connected to emitter 49. The degree of braking afforded by the traction motors depend upon the current supplied to the motor fields by the generator, and the wheel speed. As the engine speed is increased, a higher voltage is established across the braking resistor 78 to cause a balanced condition in which coil 42 draws steady current. |
