Patent GB-278323-A (GB)
Title: Improvements in or relating to electric distant control systems
IPC: G08C19/38
Filed: 1927-07-23
Abstract: 278,323. Granat, E., and Compagnie des Forges et AciÚries de la Marine et d'HomÚcourt. Sept. 28, 1926, [Convention date]. Selective distant control systems.-In an electric distant control system wherein the position of a receiver motor is controlled by a set of movable brushes which co-operate with the commutator of a dynamo electric machine or a stationary winding and the part, such as a gun, controlled by the receiver has a limited movement, means are provided for rendering the receiver inoperative when the brushes of the transmitter are moved beyond corresponding limits of movement. As shown in Fig. 1, the armature 2 and field 1 of the transmitter T<1> are supplied from D.C. mains. Brushes 6, 7, 8, resting on the commutator 3, are mounted on the controlling shaft 15 and feed the line wires 12, 13, 14 which supply the rotor of the receiver R<1>. The stator of the receiver comprises a distributor winding connected to a commutator 17 and fed through movable brushes 18, 19. The receiver controls a shaft 26 through an electromagnetic clutch 29 and gear wheels 27, 28 and the transmitter T' is adapted by the provision of a contact 46 on the shaft 15 to operate the shaft 26 only through a limited range of movement. When the transmitter operates within this range the clutch. 29 and a second clutch 40 associated with an auxiliary motor SM<1> are excited respectively to couple the shaft 26 to the receiver R<1> and couple through gearing which is shown diagrammatically the shaft 35 of the auxiliary motor SM<1> to a wheel 42 of a differential gearing D, the planet wheels of which control the brushes 18, 19. The motor SM<1> is controlled over the line wires 12, 13 14 by the transmitter T<1> so that within the predetermined range of movements the pinions 37, 42 of the differential gearing are driven at equal speeds to maintain the brushes 18, 19 stationary. When the transmitter brushes pass beyond the limits of the range of movements the clutches 40, 29 are de-energized. The shaft 26 is thus no longer under the control of the receiver shaft and the pinion 42 is rendered stationary, whereby the planet wheels rotate the brushes 18, 19 to cause the field of the stator to rotate at the same speed as the rotor field and bring the receiver to rest. In a modification wherein the auxiliary motor is located at a distance from the receiver, the planet wheels of the differential gearing control the brushes of an auxiliary transmitter which operates a receiver motor geared to the brushes 18, 19. Fig. 3 shows, a modified system wherein the field of the transmitter is supplied from a.c. mains. Within the specified range of movement, a clutch 78 is energized to couple the controlled shaft 82 to the receiver shaft 76, and the clutch 106 associated with the auxiliary motor SM<2> is de-energized. The auxiliary motor SM<2> drives brushes 93, 94, 95 co-operating with the stationary commutator of the winding 96 of a frequency changer E. The brushes are supplied from the, line wires 61, 62, 63 and when the clutch 106 is de-energized, brushes 98, 99, 100 controlled by the shaft 102 remain stationary on the commutator and collect constant potentials. The brushes 98, 99, 100 feed the motor winding 68 of the receiver R<2>, the stator winding of which is supplied over the line wires 61, 62, 63. Thus within the range of movement the receiver rotor follows the field of stator the displacement of which is controlled by the transmitter brushes 54, 55, 56. When these brushes pass beyond the range, the clutch 78 is de-energized and the clutch 106 is energized. The brushes 98, 99, 100 are then driven by the auxiliary motor SM<2> at the same speed as the brushes 93, 94, 95 so as to produce polyphase currents in the leads 73, 74, 75. A field is thus set up in the rotor of the receiver which rotates at the same speed as the stator field to cause the receiver to stop. In a modification the frequency changer E is replaced by an auxiliary transmitter having a field winding supplied from the mains.