JPS6116207A - Labyrinth seal device - Google Patents

Abstract

PURPOSE:To enable regulation of radial movement of each seal piece to improve sealing performance, by a method wherein a labyrinth seal is divided into plural seal pieces to contain it in an annular gap, and a ring cam, located between the seal piece and a stationary body, is displaced in a peripheral direction. CONSTITUTION:A labyrinth seal 3, divided into plural seal pieces 3a-3c. is located between a stationary body 1 and a rotary body 2 of a rotary fluid machine through the medium of a press spring 4. A cam mechanism, containing a ring cam 5 adapted to drive each seal piece 3a in a radial direction, is located between the labyrinth seal 3 and the stationary body 1 to vary a fine gap between the rotary body 2 and the labyrinth seal 3 depending upon an operating condition. Namely, plural slanted projections 5' are formed on the outer periphery of the cam 5, meanwhile, a slanted recess part 3', having a space sufficient to allow containing of the projection 5', is formed in the inner side of the each seal piece 3a, and this enables the cam 5 to be circumferentially varied through operation of a piston 7, integrally formed to the cam, within a cylinder 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a labyrinth seal device used in rotating fluid machines such as steam turbines.

[Traditional extraction technique]

Conventional labyrinth seal devices include those shown in FIG. 7 (sectional view taken along the vn-vn arrow in FIG. 8) and FIG. 8 (cross-sectional view taken along the \; m-Vm arrow in FIG. 7); Fig. 9 (1X-1χ arrow sectional view in Fig. 10) and Fig. 10 (Fig. 9
There is a cross-sectional view taken along the line X-X in the figure), and both are between the stationary body 1 and the rotating body 2 in the rotating fluid 1 machine.
A link-shaped labyrinth seal 3 is interposed as a whole.

The labyrinth seal 3 includes a plurality of arc-shaped seal pieces 3.
a, and each seal piece 3a is pressed in the axial direction by a pressing spring 4 as a leaf spring, so that the seal piece 3
a are in close contact with each other so that a predetermined minute gap 8 is formed between the seal piece 3a and the rotating body 2.

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 seeks 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 have a sufficient sealing function, contact between the aforementioned seal piece 3a and the rotating body 2 will easily occur, and wear will cause the minute gap g.
There is a problem that the sealing ability is deteriorated due to the expansion of the sealing capacity.

In particular, when vibrations and transient thermal deformation of a single chamber occur when the steam turbine passes through a critical speed during startup, the labyrinth seal 3 comes into contact with the rotating body, the above-mentioned reduction in sealing performance becomes significant.

Also, during assembly, it is necessary to widen the gap between the rotating body 2 and the labyrinth seal 3, which may reduce the sealing performance by 1 degree. The number of rows of fins must be increased, resulting in a problem 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 rotor, making the aforementioned microgap wider, and in steady operation, the labyrinth seal is brought closer to the rotating body to make the microgap as small as possible to prevent leakage loss (l), and the labyrinth seal itself The purpose is to provide a labyrinth seal device that also prevents wear and tear.

[Means for solving problems]

Therefore, the labyrinth seal device of the present invention has a rotary fluid 8
! In order to form the necessary minute gap between the rotating body in the Ten Commandments and the stationary body outside the rotating body, a labyrinth seal is installed along the inner circumference of the stationary body via a pressure spring, and the labyrinth seal A cam mechanism is provided between the stationary body and the seal pieces, and a cam mechanism is provided between the stationary body and the seal pieces, and can adjust the minute gap by driving these seals in the radial direction. It is characterized in that a cam operation control mechanism for the cam mechanism is provided.

[For production]

In the double labyrinth seal device of the present invention, the labyrinth seal is divided into a plurality of arc-shaped seal pieces, and each seal piece is driven in the radial direction by a cam mechanism, so that the gap with the rotating body can be freely adjusted. Therefore, during startup, when there is a risk of contact between the seal and the rotating body due to initial vibrations and transient thermal deformation of the casing, the gap between the seal and the rotating body is sufficiently widened to prevent contact. During steady operation, where there is little risk of occurrence, the gap is adjusted to be as small as possible.

〔Example〕

Figures 1 to 6 show a labyrinth seal device as an embodiment of the present invention, and Figure 1 is a sectional view (
2 is a sectional view showing its working state, FIG. 3 is a sectional view taken along I-1 in FIG.
The figure is a cross-sectional view showing the cam operation control mechanism (IV in Figure 5).
-IV sectional view), 5M is a sectional view of FIG.

As shown in FIGS. 1 to 3, in the labyrinth seal device of the present invention, as in the conventional device, a spring 4 is provided between a stationary body 1 and a rotating body 2 in a rotating fluid machine such as a turbine. Through a plurality of seal pieces 3g, 3b
.

The labyrinth seal 3 divided into 3c,... is the device■
However, in this device, a cam 1 shallow structure including a link-shaped cam 5 for driving each seal piece 3a, 3b, . Or is provided.

A plurality of inclined protrusions 5' are formed on the outer periphery of the cam 5, and four inclined parts 3' capable of accommodating the protrusions 5' are formed inside each seal piece 3a, 3b, . . . .

Furthermore, a protrusion 3'' and a notch 3'' are provided at both ends of each seal piece 3a+3171, and as shown in FIG. The notch 3'' of the sealing piece 3b is supported by the notch e3' or the protrusion 3'' of the sealing piece 3c.

3, the end of the seal piece 3b or seal piece 3c is supported by the protrusion 5' of the cam 5 and the spring 4, and furthermore, the seal piece 3a is supported by each protrusion 3''.
Alternatively, since the notch 3'' of the seal piece 31) is supported, one protrusion 5' supports both ends of the adjacent seal pieces 3a and 3b (the notch 3'' of the seal piece 3a and the protrusion 3 of the seal piece 3b). '') are supported in common, so that the entire labyrinth seal 3 moves in the direction opposite to the axis against the spring 4, creating a sufficient initial gap 81 between the labyrinth seal 3 and the rotating body 2. The current state is shown.

Further, FIGS. 4, 5, and 6 show an example of a cam operation control mechanism for driving the cam 5, in which a cylinder 6 is provided in the stationary body 1, and the cam 5 is A piston 7 is integrally connected to the spring 8, and the piston 7 is connected to a spring 8.
It is connected to the stationary body 1 via.

The high pressure side 11 of the cylinder 6 is communicated with a high pressure section (not shown) inside the machine via a conduit 9, and the low pressure side 12 is communicated via a conduit 10 with a section having a lower pressure than the high pressure section.

In addition, in FIGS. 4, 5, and 6, the cam 5
Although a case is shown in which the pressure inside the fluid machine is used to drive the cam 5, it is also possible to drive the cam 5 from the outside. In other words, when using the pressure of the fluid used in fluid machinery, it is possible to open and close a valve installed in a conduit, when using the temperature difference of the fluid, it is possible to control the heat load of a heat pipe, and when using electromagnetism, it is possible to The cam 5 can be driven by providing an actuator inside the fluid machine and controlling the current.

Here, a case where control is performed by opening and closing a valve will be exemplified. and becomes as follows.

That is, conduit 9. A valve (not shown) is provided at the to, and by appropriately adjusting the valve, the re-piston 7 can be moved arbitrarily.

In this case, the timing of opening and closing the valve to reduce the gap between the labyrinth seal 3 and the rotating body 2 can be determined by using sensors to detect all or part of vibration, deformation of a single chamber, temperature difference, load factor, pressure, etc. It can be done automatically by

In addition to this kind of judgment, Labyrinth Seal, 3
The labyrinth seal 3 can be powered until it comes into contact with the rotating body 2, and after detecting the contact between the labyrinth seal 3 and the rotating body 2, a minute gap ε can be created between the labyrinth seal 3 and the rotating body 2. .

In this way, the minute gap g between the labyrinth seal 3 and the rotating body 2 is automatically adjusted.

Figures 1, 3, 4 and 5 show this rotating flow 1.
This shows the state before starting the machine. In this state, there is very little pressure at both ends of the piston 7, so the piston 7 remains pressed by the spring 8, as shown in Figure 5. Since the piston 7 is connected to the cam 5, the cam 5 is also elastically pushed.

That is, as shown in FIG. 3, the protrusion 5' of the cam 5 completely deviates from the recess 3' of the labyrinth seal 3.
The labyrinth seal 3 is pushed by the cam 5 in a direction opposite to the axial center against the force of the spring 1, thereby creating a sufficient initial gap 81.

Next, this rotary fluid machine operates, and as the pressure on the high pressure side 1 of the cylinder 6 increases and the pressure difference in the low pressure side 12 increases, it resists the force of the spring d, as shown in Figure 6. The piston 7 is moved by the force on the low pressure side 12 in the figure.

As a result, the force l,5 connected to the piston °7 moves in the direction of the arrow 5'' from the position shown in FIG. Due to the pressing force i of the spring 4, the labyrinth seal 3 moves in the axial direction of the rotation 14-2.

Therefore, the small gap 8 between the labyrinth seal 3 and the rotating body 2 changes from the initial gap 8 to an operating gap of 8 degrees.

Due to these operations, when the rotating body 2 is started, where contact between the rotating body 2 and the labyrinth seal 3 is likely to occur, the minute gap 8 is closed.
During steady operation when the vibration of the rotations 14 and 2 is reduced by 1ji9, it is possible to maintain the minute gap g at a relatively small operating gap.

〔Effect of the invention〕

As detailed above, according to the labyrinth seal device of the present invention, the minute gap between the rotating body and the seal can be adjusted according to the rotating flow 14 and the operating conditions of the machine, etc., so the following advantages are achieved. can get.

(1) When rotating fluid machines pass critical speeds when increasing or decreasing the rotation speed 1 Even if the vibration of the rotating body becomes large, contact between the rotating body and the labyrinth seal does not occur, so the vibration that occurs during such contact does not occur. This avoids bending of the rotating body, vibrations caused by it, wear of seals, etc.

(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) 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, thus improving the efficiency of the machine.

(4) If the drive source uses the pressure difference of the fluid inside the fluid machine as in the above embodiment to adjust the minute gap between the rotating body and the labyrinth seal, there will be no problem during the entire operation. Since there is no need to supply external energy or signals, and the microgap can be adjusted to change automatically, the control is self-contained and therefore maintenance-free, reliable and reliable. Increased durability.

(5) Since the pressure difference between the fluids inside the rotating fluid machine can be used as the drive source for the labyrinth seal, even when the seal temperature is high, the seal drive source can be used without the need for special protection measures such as heat insulation. It will be done.

[Brief explanation of the drawing]

fpJi~6 Figures show a labyrinth seal device as an embodiment of the present invention, Figure 1 is a sectional view showing the main part (cross-sectional view taken along the line I-I in Figure 3), and Figure 2 is a sectional view showing the main parts thereof. A cross-sectional view showing its operating state; FIG. 3 is a cross-sectional view taken along the ■-■ arrow in FIG. 1;
Fig. 4 is a sectional view showing the cam operation control mechanism (IV-IV sectional view in Fig. 5), Fig. 5 is a sectional view taken in Fig. Operation control (This is a cross-sectional view showing several operating states. Figures 7 and 8 show an example of a conventional labyrinth seal device. Figure 7 is a cross-sectional view showing the main part of the labyrinth seal device. Figure 8 is a cross-sectional view of Figure 7 as viewed from the \°■-\゛■ arrow.
, 10 show other examples of the conventional labyrinth seal device, and Fig. 9 is a sectional view showing the main parts (I in Fig. 10).
10 is a sectional view taken along line X-X of FIG. 1. Stationary body of rotating fluid machine, 2. Rotating body, 3. Labyrinth seal, 3'... Four parts, 3"... Protrusion, 3"
'...Notch, 3a, 3b, 3c...Seal piece, 4.
・Press spring, 5...Cam, 5'...Protrusion, 5''...
Movement direction of the cam, 6. Cylinder of the cam operation control mechanism,
7...Piston, 8...Spring, 9,10...8%l, 1
1...High pressure side in the cylinder, 12...Low pressure side in the cylinder, 8...Minute gap, GL...Initial gap, Total...Operating gap. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 ■ ヰ Figure 4 Figure 5 Figure 6 Figure 7 ■ Go ■ 4 Figure 8←■ Figure 9 i

Claims (1)

[Claims] In order to form a required minute gap between a rotating body in a rotating fluid machine and a stationary body outside the rotating body, a labyrinth seal is installed along the inner circumference of the stationary body via a pressure spring. The labyrinth seal is composed of a plurality of arc-shaped seal pieces, and a cam mechanism that can adjust the minute gap by driving these seal pieces in a radial direction is provided between the stationary body and the seal pieces. A labyrinth seal device, further comprising a cam operation control mechanism for the cam mechanism.