Patent GB-545115-A (GB)
Title: Apparatus for the damping of torsional vibrations in rotary power transmission systems
IPC: F16F15/023
Filed: 1940-11-01
Abstract: 545,115. Torsional oscillations. BOWER, G. S. Nov. 1, 1940, No. 16009: [Class.108 (iii)] In a rotary power transmitting system relative torsional vibration which may arise between two points is detected by hydraulic, electric or mechanical means adapted to operate relays by means of which such vibrations are restrained. The transmission shaft 12, Fig. 2, is liable to vibrate torsionally at the two points from which similar oil pumps 10, 11 are driven, the pumps being connected by large bore conduits 13, 14 connected by a restricted passage 15 which may be constituted by the usual pump clearance but is preferably an additional passage. Leakage of oil is made up through the non-return valve 16. When torsional vibrations occur, the pumps 10 and 11 will run cyclically alternately faster and slower so that the pressure in the two large bore conduits 13, 14 will also vary cyclically. If the pumps are large enough, the restricted passage 15 may alone enable the pumps to check the vibration, but if they are small they act only as detectors by which more powerful means are operated. Electric means for detecting such cyclical difference of pressure in the conduits 13, 14 consists of a bellows device with two compartments 18, 19 and an intermediate diaphragm carrying a contact 20 adapted to engage contacts 21, 22 alternately and thereby operate valves controlling the flow of oil in the closed circuits if more powerful pumps 23, 24 driven from the shaft 12 at points coinciding with or adjacent to the driving points of the detector pumps 10, 11. The pumps 23, 24 can be replaced by electro magnetic or other brakes controlled by the detector. In a modification, the two vibrating points on the shaft 12 are connected at different gear ratios to the two parts of a friction clutch which is operated electromagnetically from the detector circuit. In a further modification shown in Fig. 4, the pumps 57, 58 are connected to one another in a close circuit 59, 60 with a restricted connection 61 and each is driven from shaft 12 through epicyclic gearing which is cyclically increased or decreased in speed from the detector circuit. If the two pumps 57, 58 are driven at constant speed, from the shaft 12, their conduits 59, 60 are connected by a pump which is driven by a reversible motor controlled from the detector circuit so as to deliver oil to the conduit 59, 60 which is momentarily at the higher pressure so as to increase the pressure difference between the two conduits and increase the damping effect. The hydraulic and electric detector described above may be replaced by an electric detector in which two smaller generators driven from the two critical points on shaft 12 are connected in opposition by a closed circuit. When vibration occurs, the corresponding alternations of flow in the circuit operate contacts to control pumps &c. An alternative mechanical detector of vibration may consist of two centrifugal devices acting in opposition. In a modification the pumps are duplicated and driven through interconnected tiains of gearing having an elastic element so as to avoid backlash.