| 摘要 |
<p>848,209. Automatic speed-control systems. UNITED AIRCRAFT CORPORATION. Dec. 27, 1956 [Dec. 27, 1955 (2)], No. 39348/56. Class 38 (4). Propellers 12, 26, Fig. 1, are driven by motors 10 and 24, the speed of which is maintained constant by automatic adjustment of the blade pitches by hydraulically actuated pistons controlled by flyball governors 14, 28, the governor spider spring being adjustable and the adjustment being effected by a step-motor 16, 30 controlled by a commutator switch 18, 32. The commutator switch 18 for the master propeller 12 is driven by a manually-controllable D.C. motor and that for the slave is driven by a two-phase motor 34 controlled by electronic synchronizing and phasing apparatus which employs pulses produced in coil 36 by the rotation of the propeller in the manner described in Specification 846,913. Wave former unit 40, Fig. 2, and sawtooth sampler 74 producing an error signal input to chopper amplifier 112, 114. Manual phase control is provided by potentiometers 128 across a separate source 130, 132 and switches enable individual control by manuallycontrolled commutator switches such as 33 or the selection of an alternative propeller as master. The mechanical lag of the chopper is increased by additional lag in the transformer to produce in the control winding of motor 34 a signal lagging or loading the reference voltage by 90 degrees and feed-back is provided by the wiper of potentiometer 172. The amount of reset of the governors is limited by a pin 180 in a slot 182 of a gear-wheel 178 driven through gearing by the motor 34 and the potentiometer 172 is arranged to give zero output when the pin 180 is in the centre of the slot. A pushbutton 184 is provided whereby phase correction may be achieved after correction which has been made for an off-speed error leaves a phase error and wiper 172 in an off-centre position neutralizing a phase error signal. Operation of switch 184 energizes relay 186 which earths the error signal and de-energizes relay 188 to transfer governor reset motor 30 to commutator switch 18 controlling the master. The fed-back signal from 172 is in the meantime effective to return the wiper to its mid-point so that phase errors can be corrected. In cases of large error more than one actuation of the push-button may be necessary. Specifications 530,111, 678,505, 681,348 and 700,394 are referred to.</p> |
