GB1292021A - Vibration isolation systems - Google Patents

Abstract

1292021 Vibration isolating systems KINS DEVELOPMENTS Ltd 2 Jan 1970 [3 Oct 1968] 46998/68 Heading F2S Two members, such as a body 1 and a foundation supporting it are isolated against relative vibration by means of a pair of interconnected pneumatic isolators I 1 , I 2 acting in series and resilient means such as springs 3. The isolating system also includes an inertia mass 2. The arrangement is such that for low frequency vibrations isolation is effected by the pneumatic isolators and for high frequency vibrations by the springs. In Fig. 4, a " capillary " tube 4 interconnects the isolators, which are identical piston-cylinder devices. The tube 4 may have a diameter of one inch and the cylinders diameters of one foot. In the static case, or for low frequency movements of the body 1, I 1 and I 2 exert equal and opposite forces on the inertia mass 2 so that the latter is effectively supported by the springs alone. Hence low frequency vibrations of the body 1 are absorbed by the interconnected isolators. At high frequencies, the " capillary " tube is effectively blocked so that the only damping agency is the mass-spring system 2, 3. A typical characteristic is shown in Fig. 5 in which # = 0 corresponds to zero damping coefficient (i.e. unrestricted flow of fluid in the capillary tube) and # = # to infinite damping (totally blocked capillary). The damping characteristic must at all times lie within these limits, so the actual characteristic of a particular apparatus will lie within the shaded area defined by the theoretical limits on #. The Specification contains a theoretical discussion of the performance of the proposed system and its advantages over previously known isolating systems.