Patent GB-547252-A (GB)
Title: Improvements in or relating to gas meters
IPC: G07F15/00
Filed: 1941-02-19
Abstract: 547,252. Prepayment mechanism for gas meters. ROBINSON & CO. (LIVERPOOL), Ltd., J. H. ORMEROD, G. A. and SMITH, A. Feb. 19, 941, Nos. 2235 and 9969. [Class 27] In order to prevent leakage of gas past the valves of a coinfreed meter from causing the mechanism to continue working and become strained against the action of a stop device, a resilient connection which normally acts as a rigid one is interposed in the drive to the valves controlling the supply of gas to and from the measuring chambers, means being also provided for arresting some part of the drive to the valves when the gas paid for has been consumed, so that the resilient connection no longer acts as a rigid one and the meter mechanism is brought to re:t. In the construction shown in Figs. 2 and 3 arms 24, 25 operated by the diaphragms of the measuring chambers are connected by links 26 to the usual tangent arm 28 so as to rotate the latter and thereby reciprocate the slide valves 32 controlling the supply of gas to and from the measuring chambers. The valves are reciprocated by a crank pin 34 on a shaft 29 on which the tangent arm is loosely mounted, a spring 31 connecting the tangent arm to an arm 30 fixed to the shaft 29, so that normally the tangent arm drives the valves through the spring 31. When the gas paid for has been consumed a stop 35 is automatically moved into the path of the arm 30 which is held stationary together with the valves 32. The diaphragms will continue to drive the tangent arm and stress the spring 31 until they are sufficiently out of step, even if there is a leakage of gas past the usual automatic stop valve or "button". In a modification the tangent arm 28 is rigid with the shaft 29 and a resilient connection is provided between the crank pin 34 and one of the valves 32. In the construction shown in Figs. 5 and 6 the tangent arm is in two parts 28a, 28b fixed to concentric shafts 29a, 29b and normally held in line as shown, but a spring 31 acting on a pin 41 which is carried by the part 28b and works in a slot 42 in the part 28a. The tangent arm is normally rotated as a whole by means of pins 36 working in slots 37 in the tangent arm parts and in slots 38 in the arms 24a, 25a operated by the diaphragms. The slide valves (not shown) are reciprocated by means of links 33 having slots engaged by crankpins 34a, 34b fixed to the shafts 29a, 29b, as described in Specification 546,659, [Group XXIX]. When the gas paid for has been consumed the stop arm 35 is advanced into the path of the arm 28a and arrests this arm with its corresponding valve in the closed position, so that the corresponding arm 25a will be stationary. The arm 24a will continue to drive the arm 28b, the spring 31 being stressed, until the second valve is also fully closed whereupon the whole of the mechanism will be at rest. In this construction a separate stop valve or "button" is not required. In a modification, Figs. 8-10 not shown, a single crankpin 34 drives both valves 32 and is carried by a crank comprising two arms pivoted together and normally held by a spring in relative positions such that the crankpin is at the desired distance from its shaft. When the gas paid for is consumed the return mechanism of the prepayment device applies a brake to a disc having a cam slot engaged by a pin on one of the two crank arms, so that the pin travels to the other end of the slot and the throw of the crankpin is reduced to zero, the slide valves being then in their closed positions. A separate stop valve is not needed in this construction. Specifications 192,832, [Class 27], and 509,625 also are referred to.