GB337466A - Improvements in or relating to damping or oscillation-checking devices - Google Patents

Abstract

337,466. Carter, B. C. Aug. 3, 1929. Crank shafts. - Torsional vibrations in internal-combustion engine crank shafts, and other oscillations, are damped by means comprising a friction actuated solid mass or a combination of a solid and liquid mass with its centre of gravity eccentric to the crank shaft journals. The solid mass is preferably in the form of bronze discs which may slide, roll or rotate to a limited extent in eccentric cylindrical cavities of slightly greater diameter than themselves formed in the balance masses. The difference in diameter is about one-twentieth of the throw of the centre of the cavity whereby circumferential movement of the mass is limited to Œ 1.5‹. The remaining space in the cavity may be partially filled with liquidwhich, by reason of its centrifugal pressure, controls the position of the mass in the cavity. The mass may be made to float or to contact with the inner or outer periphery of the cavity by varying the quantity or density of the liquid present. The liquid, which may be mercury, or a lead-tin-bismuthcadmium alloy molten under working conditions, assists in damping by reason of friction, viscosity, inertia, splash and wave formation. In Fig. 4, - the disc masses 4 are thrust laterally against friction linings 11 on the walls of one or more cavities 1 formed in a balance mass 2 forming an extension of the crankweb, by the centrifugal force on a double conical member 9 assisted by springs 12. The end loading may be regulated by the cone angle and by the density of the cone. The cone may be replaced by a ball or by a liquid-containing capsule which distorts slightly under the centrifugal pressure of the liquid. The tendency of the discs to assume a mean radial position under centrifugal force i.e. their tendency to set themselves with their centres in line with the centres of the cavity and the shaft journal, may be augmented by springs which will then influence the natural period of the mass. In one form the cone and springs 12 are omitted. and in a further form the masses are arranged in flanged box-like members sealed by screwing or welding and these boxes are attached in balanced disposition to one or more cranks not otherwise provided with balance masses. Six boxes are shown attached in equispaced relation to a crankweb, the mass centre of the added system being on the centre line of the shaft.