GB523416A - Improvements in devices for preventing oscillations in rotating shafts - Google Patents

Abstract

523,416. Torsional and flexional vibration dampers. SALOMON, F. M. M. B. Jan. 5, 1939, No. 404. Convention date, Jan. 8, 1938. [Class 108 (iii)] [Also in Group XXVI] A torsion or vibration damper comprising one or a plurality of groups of at least two auxiliary masses which are freely connected with unifilar suspensions, the first to a part on the shaft, and the other or each of the others to the previous mass, is characterized by the fact that the geometrical and dynamic characteristics of the system are so chosen that at least one of the auxiliary masses, other than the first, oscillates by translation, without substantial rotation relatively to the shaft member. As shown in Figs. 2, 3, a mass 3 rolls on a roller-way 2 and a mass 4 rolls on the mass 3. Flanges 6 on the mass 3 form lateral guides for the mass 4. In Fig. 4, a mass 11 rolls on a roller-way 10 and the mass 11 may be in two parts bolted together by bolts 15 or may consist of two unbolted parts. Roller-ways 12 are formed for a mass 13 provided with lateral guiding cheeks 14. Other modifications are shown in which the mass 13 is in two parts, each part being flanged, and each rolling on a race in the part 11, or the mass 3, Fig. 2, may have reduced ends each forming a race for a ring, the outer surface of which forms a race for a further mass. Formulae for determining the characteristics of the system are shown in the Specification. The roller-ways may be cylindrical, or have other shapes such as double curvatures &c. and the masses may act like spherical or conical pendulums for the reduction of torsional and bending oscillations. Balls or portions of spheres mav be used for the masses of the various stages. The rotary member 5, may be the counterbalance weight arm of an aircraft engine, flywheel of an engine &c. The oscillating systems may move in planes inclined to the axis of the rotary shaft to compensate for flexional oscillations, or may move in planes which contain the axis of rotation, or are parallel with the axis. The results given by the formulae may be increased or decreased slightly so that the system is given, relatively to thedisturbing couple of the order in question, a fictitious inertia which is positive or negative so as to avoid the inconvenient critical speeds. Specifications 401,962, 439.768 and French Specification 489,337 are referred to.