Patent GB-586142-A (GB)
Title: Improvements relating to apparatus for measuring or indicating the rate of flow of liquids or gases
IPC: G01F1/24
Filed: 1944-07-13
Abstract: 586,142. Photo - electric apparatus for indicating flow of fluids. BOOTS PURE DRUG CO., Ltd., MORRISON, A. W., and RANDALL, W. J. July 13, 1944, No. 13417. -[Class 40 (iii)] [Also in Group XXXVIII] In apparatus in which the rate of flow of a fluid is determined by the height of a float in a tubular conduit, a beam of light is directed across the conduit towards a photo-electric cell and is moved by electro-mechanical driving means so that at the height at which the beam is cut off from the cell the driving mechanism is rendered temporarily inactive and an indication of the height of the beam of light is transmitted to a recording or integrating mechanism. A beam from a source 13 is reflected at 14, 16 so that it forms a beam 23 directed across the conduit 5 in which the float 6 moves in a vertical direction, the beam being further reflected to pass to the photo-electric cell 22. The beam 23 is oscillated relative to the tube 5 by a carriage 7 having a screw-threaded boss 9 engaged by a threaded shaft 10 which can be driven in opposite directions from a motor 12 through electromagnetic clutches 24, 25 operated by windings c1, c2, Fig. 6. A followup device 40 carrying contacts 41 which are closed by engagement with the lower surface of the carriage 7 is moved by a chain 42 which, as shown in Fig. 2, passes round a barrel 42a integral with a pulley 43 which carries a cord attached to a counterweight 46 and has a ratchet 47 engaged by a pawl 48 controlled by a magnet M. The position of the shaft of the pulley which corresponds to the height of the carriage and the float is transmitted to a recording or indicating, device 55. On the assumption that the winding c1 and the relay A, Fig. 6, controlled by a valve V connected to the cell 22, are energized, the carriage 7 is moved upwardly until contacts P, G are closed, thereby operating relay T and moving the contacts t1 ... t4 from the position shown. The winding c2 is energized over contact t1 and the carriage 7 moves downwardly, opening contacts P, G, but relay contacts t1 ... t4 remain in their operated position, and magnet M is not de-energized since relay A is still energized. When the carriage has moved to the position in which the beam is interrupted by the float 6, the relay A is de-energized and the current of winding c2 is broken so that the carriage is arrested. At contact a3 the magnet M is de-energized and the ratchet 47 released so that the follow-up member 40 closes contacts 41 and over contact a1 relay T is released so that the contacts t1 ... t4 assume the positions shown. Magnet M is thereupon energized and holds the ratchet in the position corresponding to the level of the carriage, and winding c1 is again energized so that the carriage again moves upward. If the cell should again be energized, this has no effect, since with contacts t1 ... t4 in the position shown, the reversal of contacts a1 ... a4 has no effect. If the float has fallen since .the last indication, the carriage 7 will move the device 40 downwards by the rotation' of the ratchet 47 under the pawl 48. If during the downward movement the interception of the beam should fail to de-energize winding c2 and clutch 25, the circuit of the relay A is opened at contacts Q, q at the downward limit of travel of the carriage 7. In a modification, Fig. 8, a double beam is employed in connection with separate photo-electric cells 22a, 22b and the carriage is moved upwardly or downwardly to follow the movement of the float. If, for example, the cell 22a is energized, relay R1 operates, opens the circuit of relay R2 and at contact 58 closes the circuit of winding c1 and clutch 24 to move the carriage upward until both beams are intercepted by the float. If the float moves very rapidly upwards, the simultaneous energization of the cell 22b has no effect and the carriage continues its upward movement until its position is opposite the float so -that both light beams are obstructed: According to the Provisional Specification, a number of small photo-electric cells located on one side of the tube are illuminated through a longitudinal slit on the opposite side of the tube, the cells being connected to relays. The interception of light by the float operates the corresponding cell and the associated relay to insert a corresponding resistance in the circuit of a recording or integrating meter.