Patent GB-556268-A (GB)
Title: Improvements in or relating to fluid-pressure responsive devices such as indicators, recorders and control mechanisms
IPC: G01F23/16
Filed: 1941-09-29
Abstract: 556,268. Telemotors. K. D. G. INSTRUMENTS, Ltd., and EVERINGTON, G. D. Sept. 29, 1941, Nos. 12612 and 12613. [Class 69 (ii)] [Also in Groups XVIII and XIX] A fluid pressure responsive device for indicating, recording or controlling mechanism, e.g. for indicating level in a petrol tank, employs a combination of capsules whereby the pressure in the fluid transmission system is stepped up or down. A casing 10, Fig. 1, is attached to the bottom of a petrol tank by a bolt passing through a bush 11 which provides means for admission of petrol into the casing. To produce the capsule, four similar corrugated diaphragms are formed by pressing, with flat centre portions and circumferential flanges. The centre portions of three diaphragms are punched out, and the four discs arranged in two pairs, the circumferential flanges being nested in each pair and sweated together. The two pairs are arranged one over the other but with their circumferential flanges turned away from one another. The inner margin of one disc is secured to the ring 13, the inner margins of the next two are secured together at 24, and the unremoved central portion of the remaining disc is secured to a rigid disc 28 which is connected to the head 17 of plug 16 by means of a smaller capsule 27, the interior of which communicates with a capillary tube 19. The space within the ring 13 communicates either with the air, or with the space above the petrol, to enable the disturbing effects of atmospheric pressure changes in the tank on the diaphragm 26 to cancel themselves out on the opposite sides of the diaphragm. The effects of these changes on the capsule 27 are not compensated. but to obtain such compensation a simple pressure transmitter is arranged in the upper part of the tank, the disturbing pressure acting only on the uprer face of the large diaphragm, and the two pressures thus derived act in onnosition on the indicator. An arrangement is described, Fig. 2 (not shown), in which the aforesaid two pressureresponsive devices are combined in a single unit. The smaller capsule 27 is replaced by a bellows and an additional similar bellows is provided subject to the disturbing pressure. and such nressure is. transmitted through a separate pipe to the indicator. Two receiving capsules such as 3R: Fig. 3, are arranged side by side and are subjected to the two pressures. which act on the twn ends of a bar 40 pivoted at its ends to the capsules. Angular movements of the bar 40 are produced only by differences in the pressures and are transmitted by a cranked member 45 rigid with the bar 40 to a cranked member 47 on a rockshaft 48, which actuates the pointer 51. Bodily movement of the member 40, 45 is not transmitted to the member 47. In another indicator, Figs. 5-7 (not shown), a pressure responsive device similar to that in Fig. 1 is employed both at the bottom of the petrol tank and at the top, and the two pressures are transmitted to the two sides of a rigid partition across the centre of a capsule. The resulting movements of the partition are transmitted to the pointer.