GB1115259A - Load measuring system - Google Patents

Abstract

1,115,259. Capacitive load cells. GENERAL DYNAMICS CORPORATION. March 6, 1967 [May 20, 1966], No. 10472/67. Heading G1N. A force or load measuring capacitive transducer comprises a pair of load receiving resilient steel plates 11, 14 (Fig. 1) held apart by a plurality of elastically deformable columns 15 which may be integral with the upper or lower plate and are uniformly distributed over the load bearing area thereof. In the spaces between the columns a capacitor plate 19 and an insulating block 20 are fixed to the upper plate and a capacitor plate 17 and insulating block 18 to the lower plate. A layer of resilient dielectric material 21 is sandwiched between the capacitor plates. Under applied load the columns are compressed and the spacing between the capacitor plates is varied. The capacitor may be connected in a bridge circuit to provide an indication of the load. Alternatively in Fig. 6 (not shown), the load sensing capacitor and a reference capacitor are connected in a differential circuit and an amplified difference voltage energizes a servomotor which drives a potentiometer to rebalance the circuit and the amount angular displacement of the motor shaft is taken as a measure of the load. In Fig. 2 (not shown) there is a plurality of elongated parallel columns laterally spaced apart and extending across the space between the load receiving plates. In Fig. 3 there is a plurality of identical columns distributed uniformly and integral with the lower load receiving plate. In Figs. 4 and 5 (not shown) a plurality of transverse apertures are formed in a solid block one pair of elongated capacitor plates being disposed in each aperture.