JPH01298927A - Rotor for rotary electric machine - Google Patents

Abstract

PURPOSE:To prevent resonance by mounting a dynamic vibration absorber having an intrinsic vibration frequency equal to that of the twisting vibration of a rotor at the rotor of a rotary electric machine. CONSTITUTION:The rotor of a turbine generator has a rotor core 1 at its center, and both sides of the core is supported by bearings 2, 3. A dynamic vibration absorber formed of an inertial ring 6 and spokes 7 is mounted at a coupling 5 with a turbine shaft 4. A relationship of (kd/Jd)<1/2>=omegan is satisfied between the rotary inertial moment Jd of the ring 6 and the twisting spring constant kd of the spoke 7, where the intrinsic vibration frequency of the specific twisting vibration of the rotor core is omegan. Thus, the vibration at the resonance frequency is absorbed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vibration damping structure for a rotor of a rotating electrical machine, and particularly to a rotor structure for a rotating electrical machine that suppresses specific torsional vibration.

(Prior art) The rotor of a turbine generator, etc. has a long iron core, and both ends of this iron core tend to vibrate and twist in opposite phases. is 50Hz, and in western Japan it is 6
An electromagnetic excitation force having a frequency of 0 Hz) and twice that frequency acts on the rotor, thereby exciting torsional vibration in the rotor.

Now, the distribution of electromagnetic force from the stator is uniform, and if the left and right moments of inertia are exactly the same when viewed from the center of the core, including the rotor core, the vibration mode in which both ends of the core twist in opposite phases will be excited. However, in reality, the moments of inertia on the left and right sides will be uneven and will be subject to excitation by electromagnetic force. However, the excitation frequency (501I in eastern Japan)
There was no problem unless the natural frequencies of the torsional vibrations of the iron core matched or were very close to each other (6011z and 120tlz in western Japan). Note that when the two match (resonance), the torsional vibration is magnified and has a great influence on the equipment.

(Problems to be Solved by the Invention) In recent years, as the capacity of turbine generators has increased, the iron core of their rotors has also tended to become longer. As a result, the natural frequency of the above-mentioned vibration mode in which both ends of the core are twisted in antiphase has become lower than before, and depending on the equipment, it has become possible that it may be quite close to the excitation frequency, or even coincide with it in some cases.

If resonance occurs, torsional vibration in the iron core expands, which is transmitted to the turbine side and causes the turbine blades to vibrate greatly. If there is a turbine blade whose natural frequency of bending vibration is close to the frequency of the torsional vibration with which it resonates, the vibration of the blade will be further amplified, leading to fatal damage.

Considering the public nature of power plants, such a situation must be avoided at all costs.

Therefore, an object of the present invention is to solve the above-mentioned problems and to sufficiently suppress the torsional vibration of the rotor even if the natural frequency of the torsional vibration of the rotor core matches the electromagnetic excitation frequency of the rotating electric machine. The purpose of the present invention is to provide a rotor for a rotating electrical machine that can perform the following functions.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the rotor of the present invention consists of an inertial mass having a rotational moment of inertia on rotation, and a support spring having a rotational spring constant, and the rotor has a natural frequency. The structure is equipped with a dynamic vibration absorber that matches the torsional natural frequency of .

(Operation) The operation of the present invention configured as described above will be explained using FIGS. 3 to 5.

FIG. 3 shows a rotor of a turbine generator, which has an iron core 1 in the center, and each side of the iron core is supported by bearings 2.3. It is now assumed that a ring 6 is attached to the coupling portion 5 with the turbine rotor 4 by spokes 7.

Let us now consider the mathematical model shown in Figure 4, assuming that the rotor core causes torsional vibration at both ends with opposite phases. In the figure, J, , J are the equally uneven concentrated moments of inertia of the rotor core divided into two parts on the left and right, k is the screw/spring constant of the core, Jd is the concentrated moment of inertia of ring 6, and k
d is the torsional spring constant of the spoke 7;

Here, if there is no Jd+kd, the vibration system is J I I
It consists of the moment of inertia of J2 and the spring k, and its natural frequency ω. It is calculated by . This corresponds to the natural frequency of the vibration in which both ends of the rotor core twist in opposite phases, and if it matches the frequency ω of torque fluctuation due to electromagnetic force received from the rotary electric machine stator,
As shown in FIG. 5(a), the amplitude of the torsional vibration increases extremely.

Now, by attaching the inertial ring Jd and the spokes kd, the natural frequency of the mathematical model shown in Fig. 4 can be found as follows. However, since the formula becomes complicated, let's assume that J□" J2
= J t J d/ J = α, and = ω
. Must be yelling. In this case, two natural frequencies of the system are found, each ω1. When ω2 is assumed, it becomes . Here, if O×α×1, then ω1゜ω2
is ω. It doesn't match, but generally ω1 ω. Therefore, the frequency ω of the torque fluctuation received from the stator is ω=ω as shown in FIG. Then, it does not become maximum, and ω.

The amplitude will increase elsewhere. That is, J
By installing a dynamic vibration reducer made of DEKD, the frequency ω of torque fluctuation from the stator is equal to the natural vibration ω of torsional vibration of the rotor core. , the amplitude of the torsional vibration does not increase, and therefore the torsional vibration is not transmitted to the turbine blades and causes fatal damage.

In addition, ω0. ω2 and ω. The interval between and can be arbitrarily set by freely selecting the value of &, that is, the size of Jd.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a rotor of a turbine generator according to the present invention, which has a rotor core 1 in the center and is supported by bearings 2 and 3 on both sides of the core. In this embodiment, a dynamic vibration reducer consisting of an inertia ring 6 and spokes 7 is attached to a coupling portion 5 with a turbine shaft 4. FIG. 2 is a sectional view of the dynamic vibration absorber, which has a structure in which an inertia ring 6 is supported by spokes 7.

The rotational inertia moment Jd of the inertia ring 6 is the valve ω.

The structure is such that the relationship (ω: natural frequency of a specific torsional vibration of the rotor core) holds true. In particular, kd can be easily adjusted by changing the size and number of spokes.

FIG. 6 shows another embodiment of the present invention, showing a cross-sectional view of a dynamic vibration absorber section, in which an inertial mass 8 and a support rod 9, which are not ring-shaped, are shown.
Consists of. Between the rotational moment of inertia Jd of the inertial mass and the torsional spring constant kd of the support rod, as shown in FIG. .

As shown in the figure, the support spring is configured in a lattice shape, has a spring effect of a spring constant kd against torsional deformation, and is configured to have an inertial mass having a rotational moment of inertia Jd. The relationship between kd and Jd is as described above.

Figure 8 shows the inertial mass 14 connected to the stud bolt 15 and nut 1.
6, the torsional spring constant of the stud bolt part can be freely adjusted by shifting the mounting position of the inertial mass to the left or right and changing the length of the stud bolt when it is attached to the fan mounting part on the rotor, for example. .

FIG. 9 shows an example in which the inertial mass 17 is attached to a sleeve-shaped spring 18, which is fixed at an arbitrary position on the rotor.

In addition, in the examples shown in FIGS. 6 to 9, the moment of inertia of the inertial mass must be Jd and the torsional spring constant kd.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a dynamic vibration absorber made of an inertial mass and a torsion spring having a natural frequency equal to the natural frequency of torsional vibration of the rotor is attached to the rotor of a rotating electric machine. As a result, even if the frequency of torque fluctuations received from the stator matches the natural frequency of this rotor torsional vibration, there will be no resonance, and coupled vibration with the turbine blades will occur, causing fatal damage to the blades. Effects such as being able to avoid giving

[Brief explanation of the drawing]

FIG. 1 is a side view of a rotor of a rotating electric machine showing one embodiment of the present invention, FIG. 2 is a sectional view of a dynamic vibration absorber, and FIGS. 3 to 5 are diagrams for explaining the effects of the present invention. , FIGS. 6 to 9 are cross-sectional views showing other embodiments of the present invention. 1... Rotor core 2... Bearing 3... Bearing
4...Turbine shaft 5...Coupling 6...Inertia ring 7...Spoke
8... Inertial mass 9... Support rod 10...
Inertial mass 11... Support spring 12... Rotor shaft 13... Fan mounting portion 14... Inertial mass 15... Stud bolt 16... Nut 17.
...Inertial mass 18...Sleeve-shaped spring agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken 3rd v! J Figure 4/l Figure 7 Figure 9

Claims (1)

[Claims] A rotor for a rotating electrical machine, comprising a dynamic vibration absorber comprising an inertial mass having a rotational moment of inertia and a support spring having a rotational spring constant, and having a natural frequency matching the torsional natural frequency of the rotor.