| 摘要 |
1069740 Vibration dampers LORD CORP 31 Dec 1964 [6 Jan 1964] 53076/64 Index B2P 3B P9G In a vibration damper 8 for suppressing vibrations in directions radial to the axis of rotation of a shaft 6, e.g. of a centrifuge 1, a non-rotating weight 10 is supported by a tension wire 71 to vibrate in radial directions with a natural frequency tuned to correspond with variable shaft speed frequency or a multiple thereof. A damper 8 is fitted to the centrifuge at each end of the shaft 6 which is driven by a motor (4), Fig. 1 (not shown), is journalled in bearings (7), and has a rotor (5) the wire 11 being anchored at one end to the casing 8 and at the other end to a disc 12 fixed to a bearing housing 13 slidable within a bore 14 in the housing 9. A key 15 in a slot 16 prevents the housing 13 from rotating the housing accommodating a ball bearing 17a the inner race 18 of which is fixed to a stub-shaft 19 connected to the shaft 6 by pivoted links 21 carrying centrifugal weights 22. As the shaft rotates the centrifugal force of the weights 22 applies an end thrust to the bearing housing 13 to tension the wire 11 with a force proportional to the square of the speed of rotation and since the vibration of the weight 10 has a natural frequency proportional to the square root of the tension in the wire 11 the natural frequency of the weight is directly proportional to the change in speed or rotation of the shaft. The wire 11 has negligible bending stiffness and the weight is substantial so that the frequency of vibration of the absorber weight is substantially proportional to the tension in the wire 11. In a modification, Fig. 3 (not shown), an impellor (23) on the shaft (6) develops a fluid pressure, which is proportional to the square of the speed of the shaft, and which is applied to the enclosed space between two parallel diaphragms (25), (26) the lower (25) of which has a greater area. The two diaphragms have their centres connected to the lower end of the wire 11. In a further modification, Fig. 4 (not shown), a vibration pick-up (27) is mounted upon the centrifuge (1) and has an output which is fed through a D.C. converter (28) and a D.C. amplifier (29) to feed a coil (30) and produce, in a force coil (31) connected to the wire 11, a force which is proportional to the square of the vibration frequency of the centrifuge. |
