Patent GB-379542-A (GB)
Title: Improvements in current impulse transmitters for alarm signal installations
IPC: G08B25/12
Filed: 1931-10-10
Abstract: 379,542. Fire and like alarm systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Oct. 10, 1931, No. 28229. Convention date, Oct. 10, 1930. [Class 40 (i).] In a non-interference system in which several alarm devices, connected in a single loop, transmit signals to a central station by means of code wheels, the code wheel at a sending station is connected with a spring-driven driving wheel by means of a coupling device which is mounted on the code wheel, or another part of the transmitter in permanent driving connection therewith, and is arranged so that the code wheel can be uncoupled and returned to its initial position if another station is sending when the transmitter is released. Normal operation. When the transmitter is released, either by pulling chain 7b or by energizing magnet 7c, the arm 7 moves in a clockwise direction and pin 7a is positioned above the notch 16d in arm 16. Arm 16 moves clockwise, holding 7 by the engagement of 7a with 16d, until 16c touches the edge of disc 15, which is rigidly connected to discs 11, 13, 17. Arm 7 opens the short circuit across the transmitter at 7f and moves out of the path of pins 5a to allow the gear train 2, 4, 5, 8 to be driven by a spring (not shown), the rate of movement being regulated by vane 10. The wheel 3 is rigidly fixed to the driving wheel 2, and the discs 11, 13, 15, 17 are connected with driving wheel 2 by pawls 19, 20 which are mounted on the disc 11 at pivot 21. When the wheel 2 commences to revolve the disc 11, 13, 15, 17 are driven through pawl 20, but as soon as 7e has opened 7f magnet 23 operates and spring 19a drags both 19 and 20 round clockwise, first removing 20 from the teeth of wheel 2 and then allowing 19 to engage the teeth. Arm 25 is also released when 23 operates and bears against the end of 16 to prevent 16c entering 15b. The discs 11, 13, 15, 17 make a complete revolution in an anticlockwise direction. Disc 13 connects the loop circuit to earth at 14 so that when the notches on code wheel 11 co-operate with spring 12 impulses are transmitted over both line wires and are repeated by relays X and Y to receiving apparatus. The first impulse, as indicated by the first gap in 11, is longer than the remainder, and on the receipt of this impulse relays X, Y connect up suitable receiving equipment. When the discs have almost completed a revolution, lug 15a moves arm 16 in an anticlockwise direction so that 7a leaves 16d and arm 7 restores to its initial position, stopping the driving movement and closing 7f. At the same time lug 24b on fixed disc 24 is engaged by part 19c of pawl 19 and disengages 19 from driving wheel 2. The discs 11, 13, 15, 17 are free to move independently of wheel 2 and are returned to their initial position by roller 18b entering notch 17a. Relay 23 releases and the apparatus is then again in its initial position. Operation when released sender is between two sending stations, say M2 and M4. Should the alarm be released when another station is sending in each of the line wires, the discs are moved off normal as before described. As however both line wires are earthed, relay 23 does not energize and the discs are driven by pawl 20. After the discs have revolved through a small angle and before code sending has commenced, as 16 is not held by 25, pin 16c drops into recess 15b and lug 16e moves between pins 5a to stop the driving train. The roller 18b has left 17a but now enters 17b and drives the discs slightly further forward so that 20b rides up on the raised portion of fixed disc 24 and pawl 20 leaves driving wheel 2. The disc 13 has connected earth at 14 to both sides of the loop. When one of the stations M2, M4 has terminated its impulse transmission, 23 operates over one of its windings, 25 moves 16, so that 16c leaves 15b and 16e moves clear of 5a, and the pawls 19, 20 are turned about 21 so that 19 engages the driving wheel 2. The impulse transmission proceeds as before described. Operation when two stations on one side of M3 are sending, say M4, M5. If the transmitter is released under these conditions, the discs commence to revolve as described above and 23 operates to change over the drive from 20 to 19. Before 13 has moved far enough to earth the loop circuit, an impulse arrives from M4 and 23 releases. Relay 23 tends to restore the drive to 20 but during the interval between the withdrawal of 19 and the engagement of 20, 18b co-operates with 17a to restore the discs to normal. Immediately afterwards 23 re-operates and during the transition period 18b again restores the discs to normal, and this operation is repeated with each impulse until impulsing from M4 is finished. Relay 23 then remains energized and the impulse train is transmitted from M3 as before described. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a coupling formed as a single unit. This subject-matter does not appear in the Specification as accepted.