Patent Application
20080206043
This application claims the benefits of European application No. 06017046.1 filed Aug. 16, 2006, both of the applications are incorporated by reference herein in their entirety.
The invention refers to a rotor for a turbomachine, wherein the rotor has a vibration reduction device, which is formed in such a way that it damps vibrations of the rotor which emerge during operation of the turbomachine.
The shafts of generators as a rule are rotationally connected to drive units, like, for example, steam turbines or gas turbines. The frequency of generator shafts lies at 50 or 60 Hertz, as the case may be. However, the generator shaft trains experience rotational vibration excitations via the generator. As a rule, it is considered that with four-pole and two-pole generators of heavy machine construction which are operated at, or at half of, the system frequency, as the case may be, double the electrical supply frequency always emerges as exciting frequency. The rotor train vibrations and the amplitudes which occur in the process are potentially very detrimental for the rotor shaft and also for the turbine blades which are connected to it, if the amplitudes which occur exceed defined values.
In order to avoid rotor vibrations with too large amplitudes, these are modulated by means of masses and/or torsional rigidity distributions along the rotor. This means that the shafts are formed in such a way that masses are attached or removed at accessible points. However, not all vibrations can be avoided by means of these measures.
Therefore, it is an object of the invention to provide a rotor in which disturbing vibrations can be effectively minimized.
The object is achieved by means of a rotor for a turbomachine, wherein the rotor has a vibration reduction device which is formed in such a way that it damps vibrations of the rotor which emerge during operation of the turbomachine.
The vibration reduction device in this case has a housing, wherein a track surface is formed inside the housing, wherein the vibration reduction device comprises a rolling body in the housing, which rolling body is arranged with capability of movement on the track surface. The invention is based on the aspect that a vibration reduction device can be simply and quickly attached on a rotor surface. The vibration reduction device in this case is formed with a rolling body which counteracts a vibration of the rotor surface. The counteraction is achieved by the presence of inertia of the rolling body.
The rolling body in a preferred embodiment is a ball or a cylinder. Especially these embodiments are simple in production, as a result of which the vibration reduction device is favorable and inexpensive.
The track surface is preferably curved, as a result of which different frequencies of the vibration reduction device can be established.
The track surface is preferably convexly curved with regard to the rotational axis of the rotor.
A fluid is advantageously contained in the housing, as a result of which the damping of the rolling body is increased. In a preferred embodiment, the vibration reduction device has a pendulum, wherein the pendulum has an oscillating mass which is arranged on an oscillating arm, wherein the oscillating arm is arranged with capability of rotation.
The oscillating arm in this case is mounted with capability of rotation around a point of rotation.
Exemplary embodiments of the invention are explained in more detail with reference to the drawing. Components which function in the same way have the same designations.
In the drawing:
In
A track surface 4 is formed inside the housing 3, wherein the vibration reduction device 2 comprises a rolling body 5 in the housing 3, which rolling body is arranged with capability of movement on the track surface 4.
During operation, a centrifugal force acts in the radial direction 6 and, in a manner of speaking, presses the rolling body 5 against the track surface 4. With a constant rotational speed, the rolling body 5 is in a neutral position and does not change its position with regard to the track surface 4. If, however, the rotational speed of the rotor 1 is not constant, but is superposed by a harmonic disturbing function, this leads to an excitation of the rolling body 5 which ultimately leads to a movement on the track surface 4. On account of inertia, a movement of the rotor in one rotational direction 7 brings about a movement in the opposite direction 8.
The rolling body 5 in this case is formed either as a ball or as a cylinder.
The track surface 4 is formed in a curved manner, so that the rolling body 5 experiences a restoring force in the direction of the neutral position 9. The inclination of the track surface 4 has an influence on the restoring force on the rolling body 5. The damping of the rolling body 5 is augmented by a fluid, like, for example, oil or a tribological fluid, being located in the housing 3 of the vibration reduction device 2.
The housing 3 can be screwed onto a basic body 10 which is arranged on the rotor 1.
The track surface 4 can be formed in a curved manner with regard to the rotational axis 11 of the rotor.
An alternative embodiment of the vibration reduction device 2 is to be seen in
In the embodiment of the vibration reduction device 2 which is shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 06017046.1 | Aug 2006 | EP | regional |
