JPS6116209A - Labyrinth seal device - Google Patents

Abstract

PURPOSE:To improve sealing performance, by a method wherein a labyrinth seal is divided into plural seal pieces to contain it in an annular gap, each seal is radially movably adjustable by means of a hydraulic type driving mechanism, and a projection, positioned facing a rotary body, is formed on each seal piece. 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, and is supported through support springs 4a and 4b. A pressurizing chamber 5, adapted to radially drive each seal 3a..., is formed between the stationary body 1 and the labyrinth seal 3, and a through-hole 7, connected to the intermediate part of a through-hole 6 for intercommunicating the high pressure side P0 and the low pressure side P2 is open to the pressurizing chamber. Further, a projection 8 is formed on the inner side of each seal piece 3a..., and the projection 8 is provided at its forward end with a support surface 9 which is formed so that gaps g1 and g2 between the rotary body 2 and the outer peripheral surface of the projection are gradually decreased toward the direction of rotation of the rotary body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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. 6 (cross-sectional view taken along the line Vl-Vl in FIG. 7) and FIG. Figure 8 ((3)
The stationary body 1 and the rotating body in a rotary fluid machine are shown in Figure \"■-\"■ arrow sectional view) and Figure 9 (IX-IX cutaway sectional view in Figure 6). Between the two bodies,
A ring-shaped labyrinth seal 3 is interposed as a whole.

The labyrinth seal 3 includes a plurality of arc-shaped seal pieces 3.
When each seal piece 3a is pressed in the axial direction by a compression spring 4 as a leaf spring, the seal piece 3a
They are in close contact with each other, so that a predetermined minute gap g 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 the casing 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 sealing performance.
The number of rows of fins in the labyrinth seal 3 must be increased, resulting in the 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 body and the aforementioned microgap is enlarged, and during steady operation, the labyrinth seal is moved closer to the rotating body to make the microgap as small as possible to prevent leakage loss and reduce wear of the labyrinth seal itself. It is an object of the present invention to provide a labyrinth seal device that can also prevent such problems.

[Means for solving problems]

For this reason, the labyrinth seal device of the present invention uses a support spring along the inner periphery of the stationary body to form a required minute gap between the rotating body and the stationary body outside the rotating body in a rotary fluid machine. The labyrinth seal is made up of a plurality of arc-shaped seal pieces, and a fluid pressure drive mechanism is provided that can adjust the minute gap by driving these seal pieces in the radial direction. is,
The drive mechanism transfers the internal pressure of the machine, which increases with the rotational operation of the rotary body, to a pressurization chamber formed between the outer peripheral surface of the seal piece and the inner wall surface of the stationary body, and to the pressurization chamber. a through hole formed in the seal piece for introduction, and a protrusion protruding toward the outer circumferential surface of the rotating body on the inside of the seal piece, the tip receiving surface of the protrusion is characterized in that it is formed so that the gap with the outer circumferential surface of the rotating body is gradually reduced in the direction of rotation of the rotating body.

[For production]

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 driven in the radial direction by a hydraulic drive mechanism,
Since the gap between the seal and the rotating body can be freely adjusted, the gap between the seal and the rotating body can be adjusted at startup, where there is a risk of contact between the seal and the rotating body due to initial vibration and transient thermal deformation of the single chamber. During steady operation when the gap is sufficiently widened and there is little risk of contact, the gap is adjusted to be as small as possible.

〔Example〕

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
1 to 5 show a labyrinth seal device as a first embodiment of the present invention. The figure is ■- in Figure 1.
■A sectional view taken along the arrows, Figure 3 is a sectional view taken along the ■-■ arrows in Figure 2, @
Fig. 4 is an explanatory diagram showing the principle of operation of the main parts of the above device, Fig. 5 is a graph showing changes in the operating state of the above device, and Fig. 6 is a labyrinth seal device as a second embodiment of the present invention. FIG.

First, the first embodiment of the present invention will be described.
As shown in the figure, between a stationary body 1 and a rotating body 2 in a rotating fluid machine such as a turbine, there is a ring-shaped labyrinth divided into a plurality of arc-shaped seal pieces 3a, 3b, 3c, . . . The seal 3 is attached via support springs 4a, 41+, and in this device, each seal piece 3a, 3b,
A pressurizing chamber 5 is formed for driving the... in the radial direction.

Each seal piece 3 a, 3 b, ... is provided with a through hole 6 that penetrates from the high pressure side (P0 side in Figure 1) to the low pressure side (P2 side in Figure 1), and further pressurizes. A through hole 7 is provided that connects the chamber 5 and the intermediate portion of the through hole 6.

In this way, the pressurizing chamber 5 and the through holes 6 and 7 constitute a part of a fluid pressure drive mechanism that drives the seal pieces 3a, 3b, 3c, . . . in the radial direction.

Note that although the support springs 4a and 4 are used to hold the labyrinth seal 3 in the neutral position, this function can also be performed by a single support spring.

Further, the mounting positions of the support springs 4a, 4b can be determined as appropriate, such as at the center or at both ends in the circumferential direction of each seal piece 3a, 3b, 3c, .

In addition, the labyrinth seal 3 has an artificial step 1 that partially reduces the gap g' between the stationary body 1 and the labyrinth seal 3.
1 is provided, thereby reducing the axial thrust acting on the labyrinth seal 3.

Incidentally, the pressure inside a rotating fluid machine generally increases as the rotation speed increases, but in this device, this internal pressure is used to control the minute gap g between the rotating body 2 and the labyrinth seal 3. First, when the rotating body 2 is stationary, the first
Due to the initial spring force of the support springs 4a and 4b shown in the figure, the labyrinth seal 3 is pushed upward from the position shown in FIG. 1, that is, in a direction opposite to the axis.

Next, when this rotary fluid machine starts operating and the two rotary bodies begin to engage, the pressure P on the high pressure side increases. At the same time as the pressure rises, the pressure pp of the pressurizing chamber 5 communicating with this high pressure side through the through holes 6 and 7 also rises, and as a result, the labyrinth seal 3 tends to be pushed down in the narrow direction.

However, the labyrinth seal 3 does not move until it overcomes the initial spring force of the support springs 4a, 4b, and when the pressure in the pressurizing chamber 5 exceeds the initial spring force, the labyrinth seal 3 will move as shown in FIGS. 1 and 2. The seal 3 is pushed down in the narrow direction.

Therefore, the minute gap g changes from the initial relatively large gap N to the sufficiently small gap rii as shown in the figure.

Due to these operations, the rotating body 2 and the labyrinth seal-3
During startup of the rotating body 2, where contact is likely to occur, the minute gap g can be kept relatively large, and during steady operation when the vibration of the rotating body 2 is reduced, the minute gap g can be kept sufficiently small.

By the way, the above mechanism alone may cause the following problems. In other words, the pressure inside the rotating fluid machine is
It often changes not only due to changes in the rotational speed of the rotating body 2 but also due to changes in the load factor, so when the load factor increases,
Pressure P on the high pressure side. becomes extremely large, and as a result, the pressure in the pressurizing chamber 5 also increases, causing the labyrinth seal 3 to increase more than necessary.
There is a risk that the rotating body 2 will be pushed down in the narrow direction and come into contact with the rotating body 2.

Therefore, in the apparatus of the present invention, as shown in FIGS. 1 and 2, each seal piece 3 a, 3 of the labyrinth seal 3 is
b.

3C, . It is formed so as to gradually decrease in the direction of rotation of the rotating body 2.

Moreover, as shown in FIG. 1, each seal piece 3a, 31+,
3c+..., there are two fins 10 in the part where the protrusion 8 is located, but in other parts, as shown in Figure @3, five fins 10 are provided.

As described above, when the pressure in the pressurizing chamber 5 increases and the labyrinth seal 3 moves in the axial direction, and its protrusion 8 approaches the surface of the rotating body 2, the fluid along the surface of the rotating body 2 Since the layer strongly contacts the inclined receiving surface 9 of the protrusion 8, a pushing force in the opposite direction to the axial direction acts on the labyrinth seal 3, and this pushing force and the support spring 4
The sum of the forces a and 4b opposes the force in the centrifugal direction generated in the pressurizing chamber 5, so that the labyrinth seal 3 is not pushed upward in the axial direction more than necessary. This prevents contact between the rotating body 2 and the labyrinth seal 3, and also keeps the minute gap g sufficiently small.

As described above, in the labyrinth seal device of the present invention, the fluid pressure drive mechanism for the labyrinth seal 3 operates through the pressurizing chamber 5 and the through holes 6 and 7, as well as the seal pieces 3a, 3b, 3. c, . . . are provided with a protrusion 8 with an inclined receiving surface 9 protruding toward the surface of the rotating body 2, so that the rotation speed of the rotating body 2 is constant regardless of the increase in the rotation speed and the load factor. An appropriate minute gap g is automatically maintained during operation, and unnecessary contact between the rotating body 2 and the labyrinth seal 3 is prevented.

Moreover, when the rotary fluid machine is stopped or at low rotation speed, and even when the load factor is small even during steady operation, the small gap E between the rotating body 2 and the labyrinth seal 3 is kept large.

In addition, when the conditions for 1) the present example to hold are found using a mathematical formula, the following is obtained.

(1) Gap a! +g2 and the pushing force (F) acting on the receiving surface 9
For the infinite width Taber support shown in Figure 4, V ; Relative velocity (cIQ/s) m ; Inclination of the receiving surface x 2 ; Receiving surface entrance coordinates (cm) x 1; Receiving surface exit coordinates (Cm ) μf; Fluid viscosity coefficient (kgu+ ・s/Cm2
)Fb; Push-up force on receiving surface (kgu+)fb, f~
: Pushing force on the receiving surface per unit width (kgw/Cm) (2) Relationship between the frictional force on the side surface 12 of the labyrinth seal 3 and the required pushing down force (-F) in the axial direction Po: High pressure side and low pressure Pressure difference with the side (kglll/Cm2) (Pressure P2 on the low pressure side = 0.) A ll = +1 ・ρp: Pressurizing area of the pressurizing chamber (C
m2) (see Figures 1 and 2) Af"-HAp-b+ff+=(1-CA), Ap
(Cm2) ... (b); Surface fi (rati L CA=b+Q
+/Ap) μ; static friction coefficient As between the labyrinth seal 3 and stationary body 1; equivalent pressurized area of the side surface of the labyrinth seal 3 (cm2
)Pp=(1-β)Po-αPo; Pressure in pressurizing chamber 5 (k
gu+/cm2) (see Figure 1) (c) Fko; initial spring force (kgu+) (spring 4a
, 4b may be Fko≧0, or there may be some play. ) k ; Spring constant (kgu+/c)go; Initial clearance (cm) 8 ; Clearance during operation (cm) Pf : Average pressure on the lower surface of labyrinth seal 3 (kgw/c
The conditions for moving the labyrinth seal 3 by overcoming the frictional force as m2) are μAsP0 using Fb in the equation (,).
≦l ApPp-AfPf-Fb-k(&-g)-F
kol...(d) Using equations (b) and (e) for equation (d), and further Fko+k
If (go-g) is omitted, μ・(As/Ap) ≦1α−(I CJ(Pf/Po)(Fb/ApPo
)l...(e) This equation (e) is a condition for this embodiment to hold true.

In addition, in FIG. 5, the rotating body 2 and the labyrinth seal 3 are shown on the horizontal axis.
Taking the gap g between and taking the positive and negative pushing forces F on the vertical axis,
A certain pressure difference P. This is a graph showing the relationship between the push-up force F and the gap g, where the two-dot chain curve ■ indicates the push-up force Fl) due to the pressure on the receiving surface 9 of the protrusion 8, and the one-dot chain line indicates the upward pressure on the straight line. Pushing down force A, P due to pressure Pp in chamber 5
p, and the dashed straight line (■) shows the case where the initial spring force Fk,=O, is negative k (go-g). Therefore, the solid curve I+n+I[[ indicates the sum of the above forces, and the value of ga at the intersection with the push-down force (-Fμ) is that the pressure on the high pressure side is P.

This is the value of the gap g when . Also, the upstream pressure P
The curve (1+n+1[[
) also increases or decreases. Therefore, since the value ga of the gap g between the rotating body 2 and the labyrinth seal 3 also changes, a desired relationship between the gap g and pressure can be provided. Since the two-dot chain line ■ has the property of rising rapidly as the gap g approaches O, as shown in the figure, the change in the gap g can be made slight.

Next, a second embodiment of the present invention will be described. As shown in FIG. 6, in this embodiment, the projections 8 in the first embodiment described above are provided on both ends of the labyrinth seal 3.

If this second embodiment is applied to a case where the diameter of the rotating body 2 is large and the length of each seal piece 3a, 3b, 3c, . . . becomes long, stable operation can be expected.

In addition, in the apparatus shown in FIG. 6, a leaf spring 4 is provided in the pressurizing chamber 5, which provides a sufficient pressing force. There is an advantage that the labyrinth seal 3 is stabilized because the vibration of the labyrinth seal 3 is reduced.

However, if a sufficient pressing force can be obtained from the pressure pp of the pressurizing chamber 5, the plate spring 4 can be omitted.

Although not shown, the following modification is also possible. That is, by providing a conduit and a valve leading to the pressurizing chamber 5 from a lower-pressure part of the external or internal part of the machine, and reducing the pressure in the pressurizing chamber 5,
If abnormally large vibrations occur during steady operation, the gap g can be kept large, so the gap g can be controlled with a high degree of freedom.

〔Effect of the invention〕

As described in detail 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 that the following advantages can be obtained.

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

(2) During transient operating conditions of a rotating fluid machine, especially when the load factor is low, non-uniform temperature distribution occurs in the stationary part, and contact with the rotating body is likely to occur due to non-axisymmetric deformation.
Although a problem similar to the above occurs, this problem can also be avoided in the device of the present invention because the gap g is maintained at an exceptionally large size.

(3) Even if the undesirable deformation described in (2) occurs and the pressure has already increased and the gap has become smaller, the principles of the present invention will ensure that the gap between any seal pieces on the circumference of the rotating body is is held constant, so there is no need to consider deformations of stationary parts under all operating conditions.

(4) Due to the effects of items (1) to (3), there is no contact between the rotating body and the labyrinth seal during all operating conditions, and high sealing performance is obtained under high load conditions. In order to avoid contact between the body and the labyrinth seal, it is no longer necessary to provide an extra gap between the rotating body and the labyrinth seal when assembling the rotating fluid machine, which reduces the leakage loss of the labyrinth seal and improves the machine efficiency will be improved.

(5) When the rotating body rotates while vibrating, the gap between the rotating body and the labyrinth seal may become uneven, and a force that promotes unstable vibration may be generated. However, in the present invention, the gap is Since it is held constant, there is no need to worry about such things.

(6) If the drive source uses the pressure 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. No need to supply energy or signals from outside,
Furthermore, since it is possible to adjust the minute gap to be changed automatically, self-contained control is possible, and therefore maintenance-free, and highly reliable and durable.

(7) Since the pressure of the fluid 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 obtained without the need for special protection measures such as heat insulation. From 1.

[Brief explanation of drawings]

1 to 5 show a labyrinth seal device as a first embodiment of the present invention. The figure is ■- in Figure 1.
■A sectional view taken along the arrows; Fig. 3 is a sectional view taken along the t-m arrow in Fig. 2; Fig. 4 is an explanatory diagram showing the principle of operation of the main parts of the above device; Fig. 5 is an illustration of the operating state of the above device. FIG. 6 is a cross-sectional view showing the main parts of a labyrinth seal device according to a second embodiment of the present invention, and FIG. 7.8 shows an example of a conventional labyrinth seal device. 7th thing
The figure is a sectional view showing the main part (\1ff-vn arrow sectional view in Figure 8), Figure 8 is a vm-vu arrow sectional view in Figure 7, and Figures 9 and 10 are the conventional Another example of the labyrinth seal device is shown, and FIG. 9 is a sectional view showing the main parts thereof (a sectional view taken along the rX-IX arrow in FIG. 10), and FIG. 10 is a sectional view taken along the X-X arrow in FIG. FIG. 1. Stationary body of rotating fluid machine, 2. Rotating body, 3. Labyrinth seal, 3a, 3b, 3c. Seal piece, 4.
・Plate springs, 4a, 4b... Support springs, 5... Pressure chambers, 6
．． 7...Through hole, 8...Protrusion, 9...Receiving surface, 10...Fin, 11...Step, 12...Adhesion surface, Fhg1rFh
+g'...Total small gap, Po...Pressure on high pressure side, P2...
Pressure on the low pressure side, pp...Pressure in the pressurizing chamber, b...Length in the axial direction of the protrusion, b...Distance between the stationary body and the rotating body, b
,...Axial length of the labyrinth seal, βbp...Distance from the high pressure side to the through hole, ρ1...Circumferential length of the protrusion, pp...Circumferential length of the outer side of each seal piece length. Sub-Agent Patent Attorney Yoshihiko Iinuma No. 1 Figure ■4 Figure 2 Figure 3 Figure 4 Figure 4 LF Figure 5 Figure 6 Figure 7 ■→ ■4 Figure 8 t ■ Figure 9 i Figure 10 ■ Procedural amendment September 28, 1985 Michibu Uga, Commissioner of the Patent Office 1 Indication of the case [Yes] Patent Application No. 136295 of 1988 2 Invention '1 Labyrinth seal device 3 Case of the person making the amendment Relationship with Applicant Postal Code 100 Address 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Name (620) Mitsubishi Heavy Industries, Ltd. 4 Sub-Agent
□ Postal code 160 Address 5-5 Minamimotomachi, Shinjuku-ku, Tokyo Date of amendment order (voluntary amendment) 6 Detailed description of the invention and drawings in the specification to be amended. 7 Contents of the amendment (1) “'KgllI] written in the second, third, fourth and eleventh lines of page 12 of the specification are all corrected to rkgrj. (2) Specification f' P p = (]-β)Po=(2Po: Pressure in pressurizing chamber 5 (kgu+/cm") (see Figure 1) written from the second line to the last line on page 13 of the book.・
(c) μ・(A s/A 11) ≦1α−(I CJ(Pf/Po) (Fl)/A
I) Po) IJ is corrected as follows. [Pp=(1-β)Po=αPo; Pressure in pressurizing chamber 5 (k
gf/cm2) (see Figure 1) (c) 1; Frictional force (kgf) Fko; Initial spring force (kgf) go; Initial clearance (cnl) g; Clearance during operation (cm) Pf: Labyrinth seal 3 Average pressure on the bottom surface (kgf/c
The condition for moving the labyrinth seal 3 by overcoming the frictional force is μAsP0 using Fb in equation (a).
≦lApPp-AfPf-Fb-k(g, g)
Fkol...(d) Using equations (b) and (C) for equation (d), and further Fka+k
If (go g) is omitted, μ・(As/Ap) ≦(Q (1~CA)(Pf/Po) (Fl)/
AIIPo)l J(3) Specification, page 14, 11-12
Delete "Press down force" written in the line. (4) "(-Fμ
)” is corrected to r-F,,J. (5) Figure 5 of the drawing will be corrected as shown in the attached sheet. (To correct the code “g1” in Figure 5 to rg-J.) 8 List of attached documents (Figure 5) 1 copy Figure 5

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 support spring, and the same The labyrinth seal is composed of a plurality of arc-shaped seal pieces, and a fluid pressure drive mechanism is provided that can adjust the minute gap by driving these seal pieces in the radial direction. A pressurizing chamber is formed between an outer circumferential surface and an inner wall surface of the stationary body, and a seal piece is formed in the seal piece to introduce machine internal pressure, which increases with rotation of the rotating body, into the pressurizing chamber. The seal piece is provided with a through hole and a protrusion protruding toward the outer circumferential surface of the rotating body on the inside of the seal piece, and the tip receiving surface of the protruding portion is in contact with the outer circumferential surface of the rotating body. A labyrinth seal device characterized in that the gap is formed so as to gradually decrease in the direction of rotation of the rotating body.