Patent GB-598353-A (GB)
Title: Improvements in or relating to speed adjusting mechanism
IPC: G05D13/00
Filed: 1944-03-06
Abstract: 598,353. Correspondence control systems. UNITED AIRCRAFT CORPORATION. March 6, 1944, No. 4130. Convention date, Feb. 3, 1943. [Class 40 (i)] [Also in Group XXXV] A control system for matching the speeds of slave and master power units having individual speed regulators, such as in multi-engined aircraft, is provided in addition with manually operable means for adjusting the regulators to a selected speed setting and at the same time rendering the automatic difference adjusting means inoperative during the manual adjustment. A follow-up device is provided to bring the manually controlled means to the new datum position established by setting a lever to the speed required. The engines M, S drive small tachometer generators 62, 63 which can be connected by relay-operated switches 66, 67 respectively to the stator 61 and rotor 61<1> of a differential 3-phase motor of the selsyn type. Any difference in the generator speeds produces rotation of the rotor 61<1> in one direction or the other, thereby rotating a commutator switch 53 to energize a step-by-step motor 52 to bring engine S into synchronism with M by adjustment of the governor 11 and the propeller pitch. The speed of the master motor M is set and controlled from a remote point by a lever 100 which is movable over a graduated scale 106 to excite one or the other of coils 77, 78 of a magnetic reversing-switch 76, in the circuit of the rotor 75 of a small motor 73<1>, which has a permanent magnet field 74 and is coupled to a commutator switch 41 controlling a step-by-step motor 35. A contact arm 97, which swings with lever 100 is located between spaced contacts 93, 94 projecting laterally from an arm 109, which is pivoted freely on a shaft 101 and carries a bell-crank lever 112 provided with an end roller 113. The roller 113 is normally located in a notch 117 in a cam 114, and held there by a tensioned spring 118 when the arm 97 is intermediate the contacts 93, 94. Movement of lever 100 to set a new speed closes contact 97 against one of the contacts 93 or 94, thereby closing contact 85 or 86 of the reversing switch to drive motor 73<1> in the requisite direction to reset commutator switch 41, and at the same time the roller 113 is brought on to a raised portion of the cam 114. A follow-up movement is provided by a gear-train, represented by 140, between the rotor 75 and cam 114, whereby the latter is rotated in a direction to restore the cam roller to the notch 117, the arrangement being such that, at the required speed setting of the governor 11 by motor 35, the roller is within the notch, and contact 97 is again intermediate the contacts 93, 94. The circuit through rotor 75 is thus broken. A relay coil 58 shunted across the rotor 75 controls two sets of switch contacts 56, 59 associated with the circuit of step-by-step motor 52 of slave engine S, whereby energization of coil 58 closes contacts 59 and puts both the step-by-step motors 35, 52 under the control of commutator switch 41 during manual adjustment and opens contacts 56 to disconnect the automatic difference adjusting device from motor 52. Specification 569,213 and U.S.A. Specification 2,071,536 are referred to.