Patent GB-678107-A (GB)
Title: Improvements in or relating to fluid rate-of-flow meters
Inventor: HAMBLETT LAURENCE SIDNEY JAMES
IPC: G01F15/06
Filed: 1950-01-31
Abstract: 678,107. Measuring rate of fluid flow. LEGG, F. F. Jan. 23, 1951 [Jan 31, 1950] No. 2545/50. Class 97 (ii). A rate of flow meter for determining the rate of flow of a fluid passing through a quantity meter, e.g. a water meter, comprises an indicator movable in one direction to indicate an increase in the rate of fluid flow by an escapement mechanism towards its position of maximum recording under the driving influence of a differential gearing operated from an element of the quantity meter rotatable by the passage of fluid therethrough, an escapement release device permitting movement of the indicator in the reverse direction to indicate decrease in the rate of fluid flow and cyclically operable timing means to determine the periods during which the indicator is respectively under the driving influence of the differential gearing and the restoring influence of the escapement mechanism. As shown, an input spindle 4 is supported in a frame 5 for rotation by a driving member in the quantity meter, the spindle 4 driving, through a differential gearing 8, a spindle 11 having a brake drum 12 secured thereto. Spindle 11 drives, through bevel gearing 13, 14 and against action of spring 25, an intermediate spindle 15 which in turn, through an escapement mechanism, drives an indicator 21 secured to a spindle 18 against action of spring 23. The escapement mechanism comprises wheel 16 loose on spindle 15 and which meshes with wheel 17 secured to shaft 18 which also has secured thereto toothed wheel 20 engaged by pawl 24. Cyclically operable timing means consisting of a set of cam devices 33, 34, 35 rotated by a synchronous motor 31 control the operation of electrical contact devices which cause the energization of electromagnets 28, 29 and 30 associated respectively with the cage 6 of the differential gearings 8, the brake drum 12 and the pawl 24 such that in a cyclical period, e.g. 6 secs., the electromagnet 28 is energized for 4 secs. to lock the cage 6 against rotation so that spindle 4 drives spindle 11 through the differential gears. If the current rate of fluid flow is higher than that represented by the then position of indicator 21 and also of a pin 44 carried by wheel 16, a pin 43 on spindle 15 will contact the pin 44 and drive the spindle 18 and indicator 21 against influence of spring 23 in the direction of maximum indication. If the current rate of fluid flow is less than in the preceding period the pin 43 will not reach pin 44. At the end of the 4 sec. period electromagnet 28 becomes de-energized and the cage 6 released, electromagnets 29 and 30 become operative to hold the brake-drum 12 and spindle 11 and to disengage pawl 24 from wheel 20. The spindle 18 and indicator are now able to return towards minimum indicator until the pin 44 strikes the pin 43 and the motion of spindle 18 is thus arrested, and indicator 21 indicates a drop in rate of fluid flow. At the end of 1 sec., electromagnet 30 becomes inoperative, pawl 24 engages wheel 20 and holds the indicator in the set position. At the end of a further half-second, electromagnet 29 becomes inoperative, releasing the brake drum and allowing spindles 15 and 11 to return under influence of spring 25 ready for another cyclic operation initiated by cam device 33 causing energization of an electromagnet 40 which in turn causes energization of the electromagnet 28. Specification 629,331, [Group XXVI], is referred to.