JPH0241394Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a labyrinth seal device used in a rotary fluid machine such as a steam turbine.

[Conventional technology]

Conventional labyrinth seal devices include those shown in Fig. 3 (cross-sectional view taken along the - arrow in Fig. 4) and Fig. 4 (cross-sectional view taken along the - arrow in Fig. 3), and those shown in Fig. 5 (cross-sectional view taken along the - arrow in Fig. 6). -A sectional view taken in the direction of the arrow) and Fig. 6 (a sectional view taken in the direction of the - arrow in Fig. 5).
A generally ring-shaped labyrinth seal 3 is interposed between the two.

The labyrinth seal 3 is composed of a plurality of arc-shaped seal pieces 3a, and each seal piece 3a is pressed in the axial direction by a pressing spring 4 as a leaf spring, so that the seal pieces 3a are brought into close contact with each other. A predetermined minute gap g between the seal piece 3a and the rotating body 2
is beginning to form.

Therefore, when the tip of the seal piece 3a comes into contact with the rotating body 2, the seal piece 3a is lifted against the pressing force of the spring 4, and the contact pressure is reduced.

[Problem that the invention attempts to solve]

However, in the conventional labyrinth seal device as described above, the minute gap g between each seal piece 3a and the rotating body 2 cannot be adjusted.

Therefore, if the minute gap g is set as small as possible in order to provide a sufficient sealing function, contact between the aforementioned seal piece 3a and the rotating body 2 will easily occur.
There is a problem in that the minute gap g expands due to wear, resulting in a reduction in sealing ability.

In particular, when vibrations and transient thermal deformation of the casing occur when the steam turbine passes through a critical speed in the initial stage of operation, causing the labyrinth seal 3 to come into contact with the rotating body 2, the above-mentioned reduction in sealing performance becomes significant.

Also, when assembling, the rotating body 2 and labyrinth seal 3
Since it is necessary to widen the gap between the labyrinth seals 3 and 3, there is a risk of reducing sealing performance during steady operation. Accordingly, a problem arises in that the length of the rotating body 2 in the axial direction becomes longer.

The present invention attempts to solve these problems by making it possible to adjust the movement of the labyrinth seal in the radial direction. The labyrinth seal is moved a little further away from the rotary body to enlarge the aforementioned microgap, and in steady operation the labyrinth seal is moved closer to the rotating body to minimize the microgap as much as possible to prevent leakage loss and prevent wear of the labyrinth seal itself. An object of the present invention is to provide a labyrinth seal device that can prevent the above problems.

[Means for solving problems]

For this reason, the labyrinth seal device of the present invention is provided with a labyrinth seal between a rotating body in a rotary fluid machine and a stationary body outside the rotating body, and the labyrinth seal is composed of a plurality of arc-shaped seal pieces. A spring is provided that urges the seal piece away from the rotating body, and the seal piece is biased toward the rotating body against the spring during steady operation of the rotary fluid machine. A space is formed between the outer circumferential surface and the stationary body, the space communicates with the gap between the stationary body and the rotating body, and the space communicates with the valved flow path. It is characterized by being connected to the low pressure section through the

[Effect]

In the labyrinth seal device of the present invention described above, the labyrinth seal is divided into a plurality of arc-shaped seal pieces, and each seal piece is biased by a spring in a direction away from the rotating body. During startup, when there is a risk of contact between the seal and the rotating body due to thermal deformation, a sufficient gap is maintained between the seal and the rotating body.

During steady operation with little risk of contact, the pressure in the space formed between the outer peripheral surface of the seal piece and the stationary body is higher than the pressure in the gap between the stationary body and the rotating body. So,
Due to the pressure difference, each seal piece is brought closer to the rotating body against the spring, thereby achieving a sufficient sealing function.

〔Example〕

Hereinafter, a labyrinth seal device as an embodiment of the present invention will be explained with reference to the drawings. It shows a cross section taken along arrow a-a in Figure 1, and the left half shows b-- in Figure 1.
FIG.

As shown in FIGS. 1 and 2, the labyrinth seal device of the present invention also has a plurality of arc-shaped seals between a stationary body 1 and a rotating body 2 in a rotating fluid machine such as a turbine, as in the conventional device. Piece 3a,
A labyrinth seal 3 divided into parts 3b, .
A corrugated plate-shaped spring 4 is provided that biases ... away from the rotating body 2.

Further, a space 12 is formed between the outer peripheral surface of each seal piece 3a, 3b, ... and the stationary body 1, and the space 12 is a gap 13 between the stationary body 1 and the rotating body 2.
are communicated with each other via a constriction portion 12a having a small gap c.

Furthermore, in this device, a communication hole 6a that communicates with the space 12 is formed in the stationary body 1, and a pipe line 9 that communicates with a low pressure section 7 inside the rotary fluid machine via a valve 8 is connected to the communication hole 6a. It is connected. This pipe line 9 is connected to a stationary body 1 that leads to another seal piece space.
It is also connected to the communication hole 6b.

Each of the seal pieces 3a, 3b, . It is prepared so that it can be engaged with.

Further, each seal piece 3a, 3b is provided with a stopper 33 that restricts the limit in the direction of approaching the rotary body 2 so as to be able to engage with the stationary body 1.

The stationary body 1 has a spring 4 as shown in FIGS.
It is provided with a spring receiver 11 for receiving the spring.

Each seal piece 3a, 3b,... has a pair of protrusions 36, 37 at one end, as shown in FIG.
The convex portion 3 on the other end adjacent to the concave portion between the
The labyrinth seals 3 and 5 are combined in such a way that they fit together, thereby allowing the diameter of the labyrinth seal 3 to be enlarged and reduced.

Since the labyrinth seal device of the present invention is constructed as described above, when this rotary fluid machine is not in use, each seal piece 3 of the labyrinth seal 3
a, 3b, .

At the initial stage of operation of this rotary fluid machine, the valve 8 is kept open, and the low pressure section 7 is thereby kept open.
Low pressure fluid from is introduced into the space 12. On the other hand, the pressure in the gap 13 increases with the operation of this rotating fluid machine, and due to the pressure difference between the high pressure in the gap 13 and the low pressure in the space 12, each seal piece 3a, 3b,... It is reliably maintained at the limit position by the stopper 31 when moving away from the rotating body 2.

Note that the space portion 12 and the gap 13 are the aperture portion 12a.
, the above-mentioned pressure difference can be maintained efficiently.

By keeping the seal pieces 3a, 3b, ... in a position away from the rotating body 2 in this way, labyrinths caused by vibrations and transient thermal deformation of the casing when the rotating fluid machine passes through a critical speed at the initial stage of operation can be avoided. This sufficiently prevents the seal 3 from coming into contact with the rotating body 2.

Next, when this rotary fluid machine enters a steady operating state and the rotation of the rotating body 2 becomes stable, the valve 8 is closed and relatively high stagnation pressure from the gap 13 is introduced into the space 12. Seal pieces 3a, 3
b, .

Therefore, each seal piece 3a, 3b,... can be brought closer to the rotating body 2 against the spring 4, and the minute gap g is sufficiently narrowed to the limit state by the stopper 33, resulting in a good sealing effect. is obtained.

At this time, the throttle part 12a can block fluctuations in the stagnation pressure in the gap 13 and contribute to stably maintaining a relatively high pressure state in the space part 12.

[Effect of idea]

As detailed above, according to the labyrinth seal device of the present invention, the minute gap between the rotary body and the seal can be adjusted according to the operating conditions of the rotary fluid machine, etc., so the following advantages can be obtained.

(1) Even if the vibration of the rotating body becomes large when passing a critical speed when the rotating fluid machine speed increases or decreases, contact between the rotating body and the labyrinth seal does not occur, so the vibration of the rotating body that occurs at the time of contact is reduced. Bending, resulting vibrations, and seal wear are avoided.

(2) In the transient operating state of a rotating fluid machine, non-uniform temperature distribution occurs in the stationary part, and contact with the rotating body is likely to occur due to non-axisymmetric deformation, resulting in the same problem as in item (1). However, this can also be avoided with the device of the present invention.

(3) Since there is no need to provide an extra gap between the rotating body and the labyrinth seal when assembling the rotating fluid machine, the leakage loss of the labyrinth seal can be reduced, thereby improving the efficiency of the machine.

(4) Since the spring and the pressure difference of the fluid inside the fluid machine are used to adjust the minute gap between the rotating body and the labyrinth seal, no energy or signals are supplied from the outside during the entire movement. Since there is no need for it and the micro gaps are changed automatically, self-contained control is possible, thus making it maintenance-free and highly reliable and durable.

(5) Since the fluid pressure difference inside the rotating fluid machine is used as the driving source for the labyrinth seal, there is no restriction from environmental conditions.

(6) When the rotary fluid machine is not in use or when it is started,
Since each seal piece is held away from the rotating body by the action of the spring, damage to each seal piece can be sufficiently avoided.

[Brief explanation of drawings]

Figures 1 and 2 show a labyrinth seal device as an embodiment of the present invention. Figure 1 is a cross-sectional view showing the main parts (cross-sectional view taken along the - arrow in Figure 2), and Figure 2 is a right-hand side view. 1 is a cross-sectional view showing a cross section taken along line a-a in FIG. 1 in one half, and a cross-sectional view taken along line b-b in FIG. 1 in the left half; FIGS. 3 and 4 are examples of conventional labyrinth seal devices; FIG. 3 is a cross-sectional view showing the main part thereof (a cross-sectional view taken along the - arrow in FIG. 4), and FIG. 4 is a cross-sectional view taken along the - arrow in FIG.
5 and 6 show other examples of the conventional labyrinth seal device. It is a - arrow sectional view of. 1... Stationary body of rotating fluid machine, 2... Rotating body,
3...Labyrinth seal, 3a, 3b...Seal piece, 4...Spring, 6a, 6b...Communication hole, 7...
Low pressure part inside the rotating fluid machine, 8...Valve, 9
... Pipe line, 11 ... Spring receiver, 12 ... Space part,
12a...Aperture part, 13...Gap, 31, 33...
...stopper, 34...protrusion, 35...protrusion, 3
6, 37...Protrusion, c...Small gap, g...Minute gap.

Claims (1)

[Scope of utility model registration request] A labyrinth seal is provided between a rotating body and a stationary body outside the rotating body in a rotating fluid machine, and the labyrinth seal is composed of a plurality of arc-shaped seal pieces, and the direction in which these seal pieces are moved away from the rotating body A spring is provided to bias the
In order to cause the seal piece to approach the rotating body against the spring during steady operation of the rotating fluid machine,
A space is formed between the outer peripheral surface of the seal piece and the stationary body, the space communicates with the gap between the stationary body and the rotating body, and the space is connected to the valve. A labyrinth seal device characterized in that it is connected to a low pressure section through a flow path.