GB708059A - Improvements in torsional oscillation dampers - Google Patents

Abstract

708,059. Torsional vibration dampers. BRITISH THOMSON-HOUSTON CO., Ltd., and FITCHETT, F. Aug. 27, 1951, No. 23675/50. Class 108(3) An asynchronouslyoperating t o rs io n a 1- vibration damper comprises coaxial, spaced, relatively - rotating g masses 2, 4 rigid with and rotatably mounted on respectively, the shaft 1 to be damped, one only (as shown, 4) of either mass being provided with spaced magnetized or magnetizable sole pieces 7. The undirectional flux between the pole pieces 7 enters and (on relative rotation between the masses 2, 4) generates eddy currents in one of the masses 2, 4 and thereby damps relative oscillations between the masses 2. 4 of any frequency. The pole pieces 7 are energized by a winding 8 connected to slip rings 9. Alternatively, Fig. 4, (not shown) the pole pieces may be carried by the flywheel 2, the slip rings then being on the shaft 1. The surface of the member in which the eddy-currents are formed may be of copper, or copper bars may be inserted in slots in the surface. Alternatively, the surface may be formed by a laminated steel core which carries a short-circuited squirrel-cage winding, Fig. 5 (not shown). The energization of the pole pieces 7 may be varied in order to vary the degree of damping. In the construction shown, the pole pieces are alternately of opposite polarity . In another construction the pole pieces are arranged in two axially-spaced circumferential series, the pole pieces of one series being of common polarity to one another and opposite to that of the other series. The pole pieces may comprise permanent magnets. The annulus 4 and flywheel 2 may be mounted on separate, but coaxila, shafts. The annulus 4 may be journalled directly on the shaft 1. Specification 531,122 is referred to.