GB771421A - - Google Patents

Abstract

771,421. Electric vibration measuring systems. DAIMLEB-BENZ AKT.-GES. July 20, 1955 [July 20, 1954], No. 21032/55. Class 40 (1). [Also in Group XIX] Apparatus for investigating oscillations occurring in a plurality of directions comprises an inert mass 2 freely suspended at the centre of two diagonal crosses located at right angles to one another and comprising helical springs stressed in tension. One end of each spring 4a to 4d, 5a to 5d is secured to a framework either at the mid-points of the eight edges of a cube or at the eight corners thereof and their other ends are secured to the mass 2 through adjustable means. The housing 1 is filled with fluid, e.g. a silicone oil, whereby movement is damped by vanes 15, 16, 17 and 21, 22, 23 on plungers 6, 7, 8 and their counterweights 18, 19, 20 and each plunger and counter-weight has at its end an adjustable screw, screw-on cap or bush, e.g. of brass co-operating with a resilient abutment surface inside a housing wall. The ends of the plungers 6, 7, 8 are of soft iron and in response to vibrations of a machine to which the housing 1 is screwed, move relative to coils 9, 10, 11 connected in the measuring branch of a bridge network in indicating or recording apparatus operating with carrier-frequency modulation, small axial movements of the plungers in regions of constant magnetic field producing large variations of inductance of the coils. The system may be tuned to obtain substantially the optimum damping coefficient. The coils may be replaced by condenser elements, the balance of the bridge then being affected by variation of capacity.