Patent GB-644345-A (GB)
Title: Speed and acceleration control systems
IPC: H02P9/00
Filed: 1945-10-18
Abstract: 644,345. Automatic speed control systems. BENDIX AVIATION CORPORATION. Oct. 18, 1945, No. 14977. Convention date, Oct. 30, 1944. Divided out of 644,286. [Class 38 (iv)] Means for limiting the speed and preventing hunting of a variable-speed member, such as the exhaust-driven turbo -supercharger described in Specification 644,286, [Group XXXVIII], and also for stabilizing the driving speed, comprises a generator 401 driven by the variable-speed member and connected by leads 415, 416 to the speed-controlling circuit shown in the lower half of the Figure, and by leads 550, 551 to the circuit shown in the other half for maintaining acceleration of the member within a predetermined range, the ultimate control of the supercharger being provided by the extent of opening of a waste gate in accordance with control signals fed to an electric motor which actuates the gate. The generator leads 415, 416 are connected to a high-pass filter.419 and thence to a full-wave rectifier comprising a pair of diodes 451, 452. The rectified D.C. is smoothed by a filter circuit 465 and provides a control voltage across a load resistance 475. The upper end of resistance 475 is connected to the grid 480 of a triode 481 to which a negative bias is applied by a battery 505 connected across voltage-dividing resistances 489, 530, and with the positive terminal connected to the anode through the primary winding 510 of a transformer 515. The secondary winding 500A of a transformer '500 fed from an A.C. supply is connected between the lower end of resistance 475 and the voltage divider, so that upon the speed of the generator 401 rising above a predetermined value the grid 480 of triode 481 is driven positive. The triode then conducts, and current flows through the primary winding 510 of transformer 515, and produces in the secondary circuit a pulsating signal which is amplified in the system described in Specification 644,286 and fed to one stator winding of a two-phase motor which operates the waste gate in a direction to decrease the speed of the supercharger. The rate-of-change circuit comprises a .full-wave rectifier formed by a pair of diodes 580, 581, and a smoothing circuit 595 across which is connected a resistance 600 and a differentiating circuit comprising condensers 610, 620 and resistances 631, 630. The outer ends of the latter resistances are connected to the grids 614, 624 of a balanced modulator comprising triodes 615, 625 respectively, the anodes being connected across the ends of the split primary winding 664 of a transformer 665. The secondary winding 641 of a transformer 642 (with primary in parallel with that of transformer 500) is connected between the junction of resistances 630, 631 and the strapped cathodes. At constant speed of the generator the valves are biassed equally and conduct simultaneously so that the currents in the primary windings 664A, 664B of the output transformer 665 neutralize one another. An increase of generator speed drives the grid of valve 615 more positive, and that of 625 more negative, so that a predominating pulsating direct current flows in the half 664A of the transformer primary winding 664. The corresponding E.M.F. induced in the secondary winding is fed over lines 340 to the amplifier associated with the motor controlling the waste gate of the supercharger, as described in Specification 644,286, [Group XXXVIII].