GB774328A - Transducer - Google Patents

Abstract

774,328. Electric control devices. LI, Y. T., and LEE, S. April 4, 1955 [April 14, 1954], No. 9851/55. Class 40 (1). A strain gauge transducer comprises a central spindle, a supporting plate through which the spindle passes, two pairs of rockers mounted for slight pivotal motion on the plate and connected to the spindle, one pair of rockers being disposed on each side of the plate, and strain gauge resistance windings carried by the two pairs of rockers and adapted to be differentially strained upon motion of the spindle. The transducer may be used for measuring force, pressure or acceleration producing rectilinear motion of the spindle. In Fig. 2, applied pressure on diaphragm 52 moves spindle 6 so that upper rockers 18, Fig. 1, pivot outwardly to increase the tension on the resistance windings 30, 32, Fig. 4, whilst the lower rockers 18 pivot inwardly to decrease the tension on the resistance windings 34, 36. The two pairs of resistance windings 30, 32 and 34, 36 are disposed to form a D.C. fed bridge, Fig. 3, so that indicated bridge unbalance measures the applied pressure. The apparatus has inherent temperature compensation since all four of the rockers 18 are rocked equally due to expansion and contraction and the bridge remains in balance. The resistance windings 30, 32 and 34, 36 and associated rockers form part of similar upper and lower unitary assemblies 14, 16. The mounting or supporting plate 8 is fixed to rings 10, 12 from which extend for both assemblies 14, 16 flexible legs 20 into connection with rockers 18 and the latter have inner legs 22 leading to collars 24 secured to the spindle 6. The legs 20 permit limited swings of rockers 18 on rings 10 or 12 and the collars 24 also form stops for the spindle 6. The resistance windings 30 &c. are wound around insulating pins 28 extending through rockers 18 and each winding is anchored under tension to clips 40 (see Fig. 2) on terminal posts 37. The lower unit 16 is mounted so that the plane of the rockers 18 is perpendicular to the plane of the rockers 18 in the top unit 14.