Patent GB-418542-A (GB)
Title: Device for automatically regulating the altitude of aircraft
IPC: G05D1/06
Filed: 1933-11-27
Abstract: 418,542. Regulating. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Nov. 27, 1933, Nos. 33205, 33206, and 33207. Convention dates, Nov. 26, 1932, March 18, 1933, and April 7, 1933. [Class 7 (vi).] In a device for automatically regulating the altitude of an aircraft by placing the propelling-force under the control of an altimeter which is adjusted to the desired altitude, a lever or like member of the control is adapted also for hand actuation, the hand and altimeter adjustments being independent of each other. In the construction shown in Fig. 1, a controlled member or indicator 1 of the altimeter is periodically depressed through the medium of a timing- device 5 upon an adjustable bank of contacts 2, which are connected individually with a set of contacts 6 on a fixed ring 7 co-operating with a rotatable contact disc 8, the position of which is alterable by a motor 15. The disc 8 is provided with two substantially semicircular contacts 9 with interposed insulation 10, and at the desired altitude, when the indicator 1 is depressed, it becomes associated with an insulated portion 10 of the disc 8 so that no electric circuit through the motor is completed. Should any deviation from the desired altitude occur, the indicator makes contact either to the right or left of its previous position and, by way of one of the contacts 6 and alternative circuits including the contacts 9, terminals 11, leads 12, relays 13 controlling the motor switch 14, battery 15<1>, and motor 15, drives the motor 15 in the appropriate direction to effect an adjustment of the engine control lever 21 and of the contact disc 8, which latter tends to move until the insulated portion 10 corresponds to the new position of the indicator 1. The mechanical connections from the motor include a worm shaft 16, wheel 17, shaft 18 on which is mounted an actuating-lever 20 for the control lever 21, an hydraulic damping-device 22, cranks 18<1>, 18<11> with a pin-and-slot connection 23, and shaft 25, a spring 24 tending to restore the position of the shaft 25 and disc 8. A sliding clutch 19 acting between the shaft 18 and lever 20 permits the pilot to adjust the levers 21 and 20 without affecting the elements of the connection on either side of it. By damping the movement imparted to the disc 8, the damping-device 22 prevents hunting of the aircraft about the desired altitude, while the spring 24 tends to restore the disc 8 and damper casing to their normal position. Adjustment for a new altitude is obtained by re-setting the indicator 1 and /or contact bank 2. Preferably, switches 121, 12<11> are arranged to break the motor circuit as the lever 21 reaches the limits of its movement. Modifications. In another construction (Fig. 2, not shown), the damping-device 22 is dispensed with and the disc 8 is replaced by a curved arm comprising two conducting-strips with an intervening insulating-portion. According to a further modification (Fig. 3, not shown), the indicator 1, in addition to being influenced by an aneroid barimeter or altimeter, is also subject to the influence of a vertical speed indicator or variometer, with the object of preventing hunting. Or in another arrangement, the additional control may be one regulated by the vertical acceleration, such as a pendulum weight operating in conjunction with a dashpot. In a still further modification, Fig. 6, hunting is prevented by inserting between the motor 15 and the rotary contacts 8<1>, 8<11> a velocity-ratio change gear comprising essentially a disc 73 rotated at a constant speed and a co-operating disc 69 normally disposed dentrally in relation to the disc 73, but displaceable to an eccentric position when the change of altitude is sufficiently rapid to influence a damping-device 65.