| 摘要 |
798,971. Automatic speed control. GARRETT CORPORATION. Feb. 7, 1956 [Feb. 14, 1955], No. 3772/56. Class 38 (4). In a speed control system a governor is adjusted in accordance with variations in operating speed in relation to the speed of a resonator controlled synchronous motor. A pneumatically operated turbine 10, Fig. 1, driving an alternator 11 through a gear-box 14 has the flow of input fluid regulated by a pneumatic unit 13 in response to changes in governor 12 brought about by a reversible servomotor 20. In the control system the inputs to a computing differential 26 are pro-. vided by synchronous motors 22, 29, the former being fed from the alternator output and the latter from an amplifier 31 which is also powered by the alternator but delivers to the motor an A.C., the frequency of which is determined by a resonator 32. The differential output is applied to a further differential 37 through a gearing 35 and drives a contact arm 41 through a slipping clutch 3 to energize increase or decrease solenoids 52, 53. The solenoid besides energizing the servomotor in the appropriate direction to effect correction, energizes a free running motor 65 providing a second input to differential 37 whereby the arm 41 is reversed. A relay 48 delays the connection of earth at 47a to arm 41 when the alternator is running up. In modifications, Figs. (2-5), Figs. 2, 3 and 4 of which are not shown, the variable input to differential 26 is provided by a direct mechanical drive from gear-box 14 and in the embodiment described with reference to Fig. 2, the governor is driven, through a slipping clutch, by the output of a single differential corresponding to differential 26. In the embodiments described with reference to Figs. 3 and 4, the D.C. motor drive to differential 37 is replaced by a direct drive from the servomotor and in the former a fluid-operated servomotor is used. Potentiometer arm 77, Fig. 5, is driven through a slipping clutch 71 by differential 26 and the unbalance of bridge 82, 83, 84 is applied to a phase shifting saturable reactor 79 to control the rotation of motor 20. The operating point of a spring-loaded governor, Fig. 6 (not shown), is controlled by adjusting the compression of a helical spring. The resonator 32 may be a tuning fork or crystal. |
