| 摘要 |
<p>958, 597. Automatic speed control systems. S. SMITH & SONS (ENGLAND) Ltd. Dec. 14, 1962 [Sept. 15, 1961], No. 33173/61. Drawings to Specification. Heading G3R. [Also in Division G4] The invention relates to synchronizing gas turbines in a multi-engined aircraft. The speed phase error signal is derived by generating a pair of quadrature speed signals for each engine i.e. the speed signals for No. 1 engine will be in the form A o sin (# + ##)t, and A o cos (w + ##)t, while the signals for No. 2 engine will be in the form A o sin #t, and A o cos wt. These signals are processed by multiplying, adding and differentiating to extract the error signal of variable sense and magnitude which actuates a reversible servomotor to control the fuel supply to No. 1 engine. The calculation of the error signal is illustrated in block diagram form by Fig. 1 (not shown). Calling the above speed signals from No. 1 and No. 2 engines, A, B and C, D, for brevity the process involves:- (i) Product signals AC, AD, BC, BD produced by chopper modulators 7.. 10 (ii) Outputs serially connected to produce sum and difference signals AC + BD and AD - BC. (iii) After filtering at 11,12 differentiated at 13, 14 to produce (AC + BD) dt and (AD - BC)dt (iv) Further product signals produced by choppers 15, 16:- AC + BD)dt x (AD - BC) and (AD - BC)dt x (AC + BD). These signals are added at 17 and the Specification shows that the result will be ##. Circuit details described with reference to Fig. 2 (not shown) show a three-phase tachometer generator 1, feeding Scott-connected transformers 30, 31 providing quadrature outputs at their centertapped secondaries 5s, 5c to the bases and emitter/ collector electrodes of a pair of symmetrical transistors 32 forming the chopper modulator. The output is differentiated by transformer 40 and applied to a further transistor-chopper. Specification 912,163 is referred to.</p> |
