Patent GB-574516-A (GB)
Title: Improvements in or relating to devices for damping torsional vibration
IPC: F16F15/173
Filed: 1943-07-26
Abstract: 574,516. Torsional vibration-dampers. BOWER, G. S. July 26, 1943, No. 12156. [Class 108 (iii)] A device for damping torsional vibrations in a rotatable member comprises a rotatable, liquid-filled, double-ended cylinder and a fly-wheel mounted in the cylinder, the cylinder or the flywheel being secured to the torsionally vibratable member so as to rotate therewith and being rotatable relatively to each other about the axis of the cylinder and constrained to move relatively axially to each other when relative rotation occurs so that the fly-wheel acts as a piston in the cylinder, a leakage passage being provided from one end of the cylinder to the other, displacement of liquid through which, by the fly-wheel, damps the vibrations. As shown, the device is applied to the cam-shaft 10 of a fuel-injection pump 11 for an internal-combustion engine, one end of the shaft projecting from the pump through a bearing 12 into a casing 13 bolted to the end of the pump and closed by a cover 14. A cylinder 15 closed by a cover 19 and containing an air bleed-hole 20 is formed with a spigot 16 having a tapered bore adapted to be keyed on the tapered end of the camshaft by splines 17 so as to rotate therewith. A sleeve 21, screwthreaded externally with a quick multi-start thread, is splined at 22 on the spiot, or formed integrally therewith, and a similarly-threaded fly-wheel 23 is mounted on the sleeve and centralised in the cylinder by springs 24, 25. The leakage passage is provided by a small clearance 26 between the periphery of the flywheel and the adjacent cylinder wall. Normally the cylinder and fly-wheel rotate as one with the cam-shaft, the fly-wheel being centralised in the cylinder. When torsional vibration of the shaft occurs, the cylinder also vibrates torsionally while the fly-wheel continues to run at constant speed and thus is caused to vibrate axially in the cylinder forcing oil through the clearance 26 which throttles the flow and damps the vibrations. The bearing 12 is lubricated by oil under pressure supplied through a connection (not shown) and a passage 27 to an oil-groove 28 from which it is forced through a passage 29 in the shaft and passage 30 in the spigot 16 and sleeve 21 to the threaded surface of the sleeve. Oil which leaks from the cylinder into the casing and lubricating oil from the pump bearing, which flows through a connection 32 into the casing, is drained therefrom through a pipe 31. In a modification (not shown) the cylinder is filled with oil and completely sealed. In another construction (not shown), the cylinder is screwthreaded internally and the fly-wheel is screwthreaded externally to screw into the cylinder. The sleeve 21 is omitted and the leakage clearance provided between the bore of the fly-wheel and the spigot 16. The spigot may, however, be omitted and the cylinder secured on the cam-shaft externally by other means, the fly-wheel being formed without a bore. Alternatively, the fly-wheel may be secured on the cam-shaft and the cylinder rotatably mounted thereon with limited freedom to move axially. In the last two modifications, the leakage passage is formed in the fly-wheel and/or the cylinder. Specification 574,517, [Group XXVII], is referred to.