JPH01182648A - Axial vibration reducer for rotary machine - Google Patents

Abstract

PURPOSE:To make stable vibration reducing force producible by connecting a pair of joint parts of a turning shaft provided with a magnet so as to cause both N and S poles to be opposed to each other, while constituting it to set up an electromagnet on each peripheral surface of these joint parts with a radial clearance. CONSTITUTION:A pair of joint parts 1, 2 of a turning shaft are connected to each other so as to cause an N pole and an S pole of permanent magnets 3, 4 to be opposed to each other via a fixture 5 of bolt and nut. On the other hand, at the radial outward of the paired joint parts 1, 2, an electromagnet 6 is fixedly set up there so as to space a specified interval in a gap with each outer surface of these joint parts 1, 2. In this electromagnet 6, its magnetic force is displaced according to the magnitude of a current flowing into an exciting coil 7, thereby varying attraction to be produced between the S pole of the permanent magnet 3 and the N pole of the electromagnet 6 or the N pole of the permanent magnet 4 and the S pole of the electromagnet 6, and the attraction conformed to force F being produced in the axial direction is given thereto. With this constitution, an axial position of the turning shaft is stably kept up all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an axial vibration damping device for a rotating machine in which a plurality of shafts are connected, such as a steam turbine.

(Prior art) For example, in order to suppress the axial positioning and displacement vibration of rotating machinery such as steam turbines and generator rotors, it is used separately from the journal bearing that supports the rotating shaft, or in combination with this journal bearing. A thrust bearing is installed.

The thrust bearing used in the rotor of a steam turbine is configured so that the thrust collar fixed to the rotating shaft slides through an oil film due to oil lubrication. When an axial disturbance is added and a resonant frequency component exists in the axial direction of the rotating shaft,
The rotating shaft reacts in the axial direction within the gap between the thrust collar and the thrust bearing, causing problems with the strength of the oil-lubricated thrust bearing due to lack of oil film on the bearing or excessive increase in thrust load.

That is, FIG. 4 shows the oil film characteristics obtained by numerical analysis of an oil-lubricated thrust bearing as oil film force versus axial displacement ratio in the thrust gap. According to the graph shown in Figure 4, when an axial disturbance caused by an earthquake or the like is applied and the rotating shaft resonates in the axial direction and exhibits a large response, the response exhibits nonlinear characteristics based on oil film characteristics. It is difficult to understand the response.

(Problem to be solved by the invention) However, with the thrust bearings of rotating machines of the above type, it is difficult to predict the response to external disturbances such as earthquakes due to the oil film characteristics of the thrust bearings, and in some cases, the boundary lubrication region is reached and the oil film A break may cause contact between the thrust collar and the thrust bearing, causing a serious accident.

The present invention has been made in view of the above points, and is capable of quickly responding to disturbances such as earthquakes occurring in the axial direction of a rotating machine.
An object of the present invention is to provide an axial vibration absorbing device for a rotating machine that generates a stable vibration absorbing force.

[Structure of the invention]

(Means for Solving the Problems) The axial vibration absorbing device for a rotating machine of the present invention connects a pair of joint parts of a rotating shaft provided with a magnet so that the N pole and the S pole face each other, and the joint part It is constructed by arranging electromagnets with radial gaps on the outer peripheral surface of the magnet.

(Function) In the axial vibration absorbing device for a rotating machine of the present invention, a magnetic force is generated between the magnets provided at the pair of joints of the rotating shaft and the electromagnets arranged with a radial gap on the outer peripheral surface of the joint. Since an attractive force is generated by If the equilibrium position is maintained in the same state, and the displacement exceeds the allowable relative displacement, suction force (thrust force) is applied to keep the axial displacement within the allowable value, and maintains a constant and safe axial position. I have to.

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

Figure 1 shows the principle of a rotating machine axial absorption device.
Reference numeral 1.2 in the figure indicates a pair of joints for a rotating shaft of a rotating machine such as a rotor of a steam turbine, and one side of the outer peripheral surface of the flange of one joint 1 has a ring-shaped permanent surface with an S pole. A magnet 3 is embedded therein, and a ring-shaped permanent magnet 4 having an N-pole surface is embedded on one side of the outer peripheral surface of the flange of the other joint portion 2 .

The pair of joint parts 1 and 2 of the rotating shaft are made up of permanent magnets 3.4.
Fixing tool 5 of the bolt nut so that the N and S poles of
are connected via.

On the other hand, an electromagnet 6 is fixedly arranged radially outward of the pair of joint parts 1.2 so as to be spaced from the outer surfaces of the joint parts 1, 2 by a predetermined distance.

The electromagnetic force of this 'W1 magnet 6 is adjusted by the current flowing through the excitation coil 7, while the Nli
A housing 8 such as a coupling guard, which is a stationary part, is arranged such that the S pole faces the S-pole ring-shaped permanent magnet 3 of the joint part 1 and the S-pole faces the N-pole ring-shaped permanent magnet 4 of the joint part 2.
(See Figure 2).

The electromagnets 6 are arranged at a predetermined distance in the radial direction from the outer periphery of the joints 1 and 2 of the rotating shaft, and the electromagnetic force is displaced depending on the magnitude of the current flowing through the exciting coil 7, and the permanent magnet 3 is S pole and N pole of magnet 6, or N pole of permanent magnet 4
By changing the attractive force generated between the pole and the S pole of the electromagnet 6,
Provides a suction force corresponding to the force F generated in the axial direction. Thereby, the axial position of the rotating shaft is always stably maintained.

FIG. 2 is a diagram showing a system of an axial vibration absorbing device for a rotating machine according to the present invention, in which two electromagnets 6°6 are attached to a rotating shaft 11.
It is located on the diameter line of electromagnet 6
The excitation coil is divided into two systems: a control coil 7a and a bias coil 7b.The control coil 7a carries a control current IC controlled by an electronic control circuit system, and the bias coil 7b carries a constant current. A generator 9 causes a constant bias current 1b to flow.

Further, a non-contact type displacement meter 10 is arranged in a housing 8 such as a coupling guard. This displacement meter 10 detects the displacement of the rotating shaft 11 in the axial direction. Accelerometers 12 and 13 are provided on the end face of the rotary shaft 11 and the housing 8 such as the coupling guard, respectively, for monitoring the axial and radial accelerations relative to the rotary shaft.

When the axial displacement X of the rotating shaft 11 is detected by the non-contact displacement meter 10, the pair of joint parts 1 of the rotating shaft 11,
A force Fffi that tries to return to the original equilibrium point acts between the ring-shaped permanent magnet 3.4 provided at 2 and the electromagnet 6 attached to a housing 8 such as a coupling guard. This force F is determined by Coulomb's law, where K is the proportionality constant, where ml is the strength of the magnetic pole of the electromagnet, and m2 is the strength of the magnetic pole of the permanent magnet.

Moreover, the magnetic pole strength ml of the electromagnet is the excitation coil 7a, 7
Current 1b flowing through b is proportional to Ic, m1=Ib+
Ic...! = Become.

That is, the restoring force F can be obtained by detecting the axial displacement X and controlling the control current 1c, and can be controlled thereby.

Therefore, the electronic a control circuit system is provided with a shaft position reference setter 14, a deviation amplifier 15, a phase correction circuit 16, and a power amplifier 17, and the shaft position reference setter 14 sets a reference value for the axial position of the rotating shaft 1. , this reference value is used by 15 deviation amplifiers. On the other hand, the displacement amount obtained by amplifying the displacement amount by the non-contact displacement meter 10 via the displacement meter amplifier 18 is input to the deviation amplifier 15, and this displacement amount is compared with a reference value, and the displacement amount is input to the phase correction circuit 16. After stabilizing the control, the control is amplified by the power amplifier 17 and sent to the exciting coil 7a]]? Determine the magnitude of the fi flow.

On the other hand, the axial acceleration detected by the accelerometer 12 provided on the rotating shaft 11 is taken out via the slip linter 19, and detected by the accelerometer 13 attached to the housing 8 such as a coupling guard in the comparison operational amplifier 20. It is compared with the acceleration on the stationary part side, and the signal output therefrom is sent to the deviation amplifier 15, which constitutes an electronic control circuit system having feedback control from both sides of axial displacement and acceleration.

This makes it possible to generate an optimal vibration absorption force or balance force against static or dynamic axial disturbances.

FIG. 3 shows an example in which the present invention is applied to a steam turbine plant.
High-pressure turbine 31 and sliding bearing 3 pivotally supported at 0.30
A shaft coupling 34 between the low-pressure turbine 33 pivotally supported on a sliding bearing 32.32 and a generator rotor 36 pivotally supported on a sliding bearing 35.35. An axial vibration absorbing device shown in FIG.

In this case, since there are two shaft joints, the control signal of the electronic control circuit system 38 is sent to each axial vibration absorbing device via the distributor 39. This increases the vibration absorbing effect against all disturbances occurring in the axial direction, reduces the load on one axial vibration absorber, and improves safety.

〔Effect of the invention〕

As described above, according to the present invention, a pair of joint parts of rotating shafts equipped with magnets are connected such that the north pole and the south pole face each other, and a radial interval is provided on the outer circumferential surface of the joint parts. Since the electromagnets are arranged in the same direction, it is possible to always exert optimal, efficient and safe axial vibration absorption force against all kinds of axial disturbances, and it is possible to provide statically and dynamically stable thrust bearings. No need for a thrust bearing for lubrication.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing the basic principle of the axial vibration absorbing device for a rotating machine according to the present invention, FIG. 2 is an overall system diagram showing an embodiment of the axial vibration absorbing device for a rotating machine according to the present invention, and FIG. The figure shows an example in which the axial vibration damping device for a rotating machine of the present invention is applied to a steam turbine, and FIG. 4 is a diagram showing oil film characteristics based on numerical analysis of a thrust bearing. 1.2...Joint part, 3.4...Permanent magnet, 6...
Electromagnet, 7... Excitation coil. Figure 2

Claims (1)

[Claims] 1. A pair of joints of rotating shafts each having a magnet are connected so that the north pole and the south pole face each other, and an electromagnet is attached to the outer peripheral surface of the joint with a gap in the radial direction. An axial vibration absorbing device for a rotating machine, characterized in that: 2. The axial vibration damping device for a rotating machine according to claim 1, wherein a disturbance detector is connected to the electromagnet, and the magnetic force of the electromagnet is controlled by a detection signal from the disturbance detector.