JPS6310662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for assembling a rotor of a superconducting rotating machine, and particularly to a method for assembling a torque tube.

To describe an example of the structure of a rotor of a conventional superconducting rotating machine, as shown in FIG. A superconducting field coil 3 is fixed to 1. A room temperature damper 4 surrounds the coil mounting shaft 1 and the torque tube 2, and a low temperature damper 5 is disposed between the room temperature damper 4 and the coil mounting shaft 1. Room temperature damper 4
Both ends of the torque tube 2 are closed by the driving side end shaft 8 and the non-driving side end shaft 9 attached to these ends, and the room temperature damper 4, the low temperature damper 5, and the inside of the torque tube 2 each have a vacuum section 14. is forming. A helium outer cylinder 6 and a helium end plate 7 are attached to the outer periphery and side surface of the coil mounting shaft 1, respectively, and a liquid helium reservoir 15 is formed between the coil mounting shaft 1 and the coil mounting shaft 1. The drive side and non-drive side end shafts 8 and 9 are each supported by bearings 10,
A slip ring 11 for supplying field current is provided on the opposite end shaft 9. A heat exchanger 12 is formed or arranged in the torque tube 2, and a side radiation shield 13 is provided inside the torque tube.

In the rotor of the superconducting rotating machine configured as described above, by cooling the superconducting field coil 3 disposed on the coil mounting shaft 1 to an extremely low temperature,
By setting the electric resistance to zero and eliminating excitation loss, a strong magnetic field is generated in the superconducting field coil 3, and AC power is generated in the stator (not shown).

In order to cool and maintain the superconducting field coil 3 to an extremely low temperature, liquid helium is introduced from the center of the non-drive side end shaft 9 through an introduction pipe (not shown) formed by a helium outer cylinder 6 and a helium end plate 7. liquid reservoir 1
At the same time, the vacuum section 14 inside the rotor is maintained at a high vacuum, and the extremely low temperature superconducting field coil 3
The most common structure is that the torque tube 2 that transmits rotational torque to the coil mounting shaft 1 is made of a thin-walled cylinder, and a heat exchanger 12 is provided to minimize the amount of heat that enters the cryogenic area through the torque tube 2. be. Furthermore, side radiation shields 13 are provided to reduce heat that enters from the sides due to radiation.

On the other hand, the room-temperature damper 4 and the low-temperature damper 5 protect the superconducting field coil 3 by shielding harmonic magnetic fields from the stator (not shown), and also have the function of damping rotor vibrations caused by disturbances from the power system. On the other hand, it is common for the room temperature damper 4 to function as a vacuum outer cylinder, and the low temperature damper 5 to function as a radiation shield to the helium storage section.

In addition, in Figure 1, helium is introduced into the rotor,
Piping constituting the exhaust system and a helium introduction/exhaust device connected to the rotor are not shown.

To describe the temperature state during rotor operation, the coil mounting shaft 1 reaches the temperature of liquid helium during operation.
On the other hand, the temperature of the normal temperature damper 4 becomes the temperature of the gap between it and the stator (not shown). Since the temperature of the air gap is generally higher than the outside temperature, the coil mounting shaft 1 and room temperature damper 4
There is a large temperature difference of more than 300℃, and therefore,
When the room temperature damper 4, coil mounting shaft 1, torque tube 2, and other parts are assembled at room temperature, the length of the room temperature damper 4 ₁ = the length of the coil mounting shaft 1 ₂ +
The total length of the two torque tubes 2 is ₃ , but when the temperature reaches the temperature state during operation described above, the room temperature damper 4 rises in temperature and its length becomes (
₁ + Δ ₁ ), and the coil mounting shaft 1 cools and its length thermally contracts to ( ₂ − Δ ₂ ). As a result, the length of the torque tube 2 becomes ₃
is ₃ = ( ₁ + Δ ₁ ) − ( ₂ − Δ ₂ ) = ( ₁ − ₂ ) + ( Δ ₁ + Δ ₂ ) ∴ ₃ − ( Δ ₁ + Δ ₂ ) = ( ₁ − ₂ ). Therefore, at room temperature Damper 4 and coil mounting shaft 1
The difference in thermal expansion/contraction (Δ ₁ +Δ ₂ ) between the two is added to the torque tube 2 as an amount of elongation, resulting in a thermal stress with a high tensile load.

Various methods have been proposed in the past for the purpose of absorbing and relaxing this thermal stress in the torque tube 2.
FIG. 2 shows an example of a conventionally proposed method for absorbing thermal stress.
The difference in thermal expansion and contraction (Δ ₁ +Δ ₂ ) between the coil mounting shaft 1 and the damper 4 at room temperature is determined by the length ₄ of the bellows 16 at room temperature [ ₄ − (Δ ₁ +Δ
₂ )] is absorbed by shrinking the torque tube 2 to avoid applying a load due to thermal stress to the torque tube 2.

In addition to what is shown in FIG. 2 (not shown), for example, a flexible body may be provided in series with the torque tube 2, or one end of the room-temperature damper 4 may slide in the axial direction at the connection portion of the end shaft 8 or 9. A plan has been proposed in which the flexible body and the connecting portion absorb the difference in thermal expansion and contraction (Δ ₁ +Δ ₂ ), similar to the example of the bellows 16. .

However, in all of the conventionally proposed methods and devices as described above, the shaft vibration characteristics of the rotor deteriorate because the bellows, flexible bodies, or sliding connections do not firmly fix the two sides. Otherwise, careful consideration in design was required to prevent deterioration of vibration characteristics.

A structure in which a flexible body such as a bellows is provided to absorb differences in thermal expansion and contraction has a strong possibility of lowering the structural vibration resonance frequency (critical speed) of the rotor, and also may cause the room temperature damper 4 to slip in the axial direction. In the proposed structure, there was a possibility that self-excited whirling of the rotor would occur due to friction on the sliding surface.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is a rotation method that alleviates the thermal stress of the torque tube 2 without deteriorating the vibration characteristics of the rotor and without creating a complicated structure. The purpose is to provide a child assembly method.

In order to achieve the above objectives, this invention
When assembling the room-temperature damper 4 and the end shaft 8 or 9, a temperature difference is applied between the coil mounting shaft 1 and the room-temperature damper 4. This is intended to relieve the tensile stress generated in the torque tube 2 due to the temperature state during operation by offsetting the compressive stress.

The invention will now be described with reference to illustrative embodiments. As shown in FIG. 3, a tube 20 is wound around the outer periphery of the normal temperature damper 4 during assembly, and a high temperature fluid such as steam can flow inside the tube 20. When assembling the room-temperature damper 4 and the end shaft 8 or 9, for example, when a high-temperature fluid such as steam is flowed through the pipe 20, the room-temperature damper 4 expands, and this expanded state causes the coil mounting shaft 1 to extend. Since the torque tube 2 having a length equal to the distance between the end shaft and the end shaft is assembled, the tube 20 is removed after the assembly is completed, and when the temperature returns to room temperature, the room temperature damper 4 expands. The amount of contraction also disappears and returns to the original length, so the amount of contraction appears as the amount of compression of the torque tube 2, and therefore, compressive stress is applied to the torque tube 2. Next, when liquid helium is injected into the helium reservoir 15 and operation is started, tensile stress is generated in the torque tube 2 due to the temperature difference between the room temperature damper 4 and the coil mounting shaft 1. Since a compressive stress is previously applied to the torque tube 2, the tensile stress generated in the torque tube 2 during operation is canceled out by the tensile stress corresponding to this compressive stress, and therefore, the tensile stress is relaxed.

The magnitude of the compressive stress applied to the torque tube at room temperature after assembly is determined by the strength of the room temperature damper, coil mounting shaft, and torque tube, and the temperature difference that occurs during operation. Compressive stress may remain,
Alternatively, neither compressive stress nor tensile stress may remain at all, or tensile stress may remain, and the heating or cooling temperature is determined by these.

In FIG. 3, a case is shown in which the pipe 20 is wound around the outer periphery of the room temperature damper 4 and high temperature fluid such as steam is caused to flow inside the pipe 20, but in short, the room temperature damper 4 and the end shaft 8 or 9
Since the purpose can be achieved by heating and expanding the damper 4 at room temperature during assembly, means such as high-frequency heating may also be used.

Or, conversely, the normal temperature damper 4 and the end shaft 8 or 9
When assembling the coil mounting shaft 1, the same effect can be obtained even if the coil mounting shaft 1 is cooled and contracted. That is, for example,
By supplying a low-temperature liquid such as liquid nitrogen or liquid helium to the helium reservoir 15 through a liquid helium supply pipe built into the rotor, the coil mounting shaft is cooled and contracted, and the coil mounting shaft in that state is The length of the torque tube should be equal to the distance between the end shaft and the end shaft.In this case, when the temperature returns to room temperature, the coil mounting shaft will also extend and return to its original position.
Therefore, the torque tube is compressed by this extended amount to apply compressive stress.

As is clear from the above explanation, in this invention,
When assembling the room-temperature damper and the end shaft without using a special structure such as providing a flexible body or a sliding structure, the room-temperature damper can be heated, or conversely, the coil mounting shaft can be cooled. Since compressive stress is applied to the torque tube after assembly is completed, the tensile stress generated in the torque tube during operation with the coil mounting shaft cooled can be alleviated without deteriorating the vibration characteristics of the rotor. Moreover, the structure can be simplified and the price can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an example of a conventional structure of a rotor of a superconducting rotating machine, Fig. 2 is a sectional view similar to Fig. 1 showing a conventional structure against high thermal stress caused by a torque tube, and Fig. 3 The figure is a sectional view similar to FIG. 1 for explaining the assembly method according to the present invention. 1...Coil mounting shaft, 2...Torque tube, 3...
Superconducting field coil, 4... normal temperature damper, 5... low temperature damper, 6... helium outer cylinder, 7... helium end plate, 8
...Drive side end shaft, 9...Non-drive side end shaft, 10...Bearing, 11...Slip ring, 12...Heat exchanger, 1
3... Side radiation shield, 14... Vacuum section, 15... Helium reservoir section, 16... Bellows, 20... Tube for passing high temperature fluid such as steam.

Claims (1)

[Claims] 1. A hollow coil mounting shaft to which a coil is attached, a hollow torque tube attached to each end of the coil mounting shaft, and a hollow torque tube attached to the opposite side of the coil mounting shaft, and the entire rotor. In the method for assembling a rotor, the rotor is equipped with an end shaft that supports the coil mounting shaft and a room temperature damper that is sandwiched between the end shafts on the outer periphery of the coil mounting shaft and the torque tube. Configuring the torque tube to have a length corresponding to the distance between the end shaft and the coil mounting shaft when the normal temperature damper is heated or when the coil mounting shaft is cooled,
Next, between the end shafts, a room temperature damper heated to a predetermined temperature, a coil mounting shaft at room temperature, a torque tube and other housing members, or a coil mounting shaft cooled to a predetermined temperature, a room temperature damper at room temperature, a torque tube and others are placed. A method for assembling a rotor of a super-electric rotating machine, characterized in that the rotor is constructed by combining storage members of.