JP7225076B2 - labyrinth seal - Google Patents

Description

The present invention relates to a labyrinth seal provided in a rotating machine.

Patent Literature 1 discloses a sealing device for a fan. In this seal device, a staggered labyrinth seal portion is formed by a throttle piece projecting from the ring and a reverse throttle piece projecting from the cylindrical portion of the shroud opposed to the ring. A distance C1 from the inner peripheral surface of the cylindrical portion to the tip of the diaphragm piece and a distance C2 from the inner peripheral surface of the tubular portion to the tip of the reverse diaphragm piece satisfy the relation C2≦C1. As a result, the ring can be easily attached to the cylindrical body of the shroud from the axial direction when assembling the sealing device.

JP-A-2002-106488

A typical fan uses a rolling bearing to support the rotating shaft. In this case, since the axial center of the rotor coincides with the center of the seal stator, assembly from the axial direction is possible if the relationship C2≦C1 is satisfied as in Patent Document 1.

On the other hand, turbomachinery uses slide bearings and tilting pad bearings. In this case, considering the oil film thickness and the inclination of the pads, the rotor is designed so that the center of the rotor is positioned at the center of the seal stator during steady operation. The seal stator is assembled to the rotor when the rotor is stopped. When the rotor is stopped, the rotor and the bearing are in contact with each other, so the center of the rotor is eccentric with respect to the center of the seal stator. Therefore, unlike the case of a fan, even if the relationship C2≦C1 is satisfied, if the eccentricity of the rotor is greater than the value obtained by subtracting C2 from C1, assembly from the axial direction becomes impossible. .

Therefore, it is conceivable to satisfy C1>C2 in order to secure the mountability. However, as the value of C2 becomes smaller than the value of C1, the width of the blow-through passage formed between the throttle piece and the reverse throttle piece becomes wider, and the amount of leakage increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a labyrinth seal capable of reducing the amount of leakage while ensuring ease of assembly.

The present invention provides a labyrinth seal provided in a rotating machine comprising a first member and a second member facing the first member, wherein the first member and the second member face each other. A gap is formed between the first member and the second member so that the fluid flows from the high pressure side to the low pressure side in the flow direction perpendicular to the opposing direction, and the a first fin extending from the first member side surface toward the first member; and a second fin extending from the second member side surface of the first member toward the second member; At least two of the first fins are provided side by side along the flow direction, and the second fins are respectively arranged between the adjacent first fins to form an inlet and an outlet of the gap. is 100 kPa or more, and the distance in the facing direction from the surface of the first member on the second member side to the tip of the first fin on the lower pressure side than the second fin is C1, the second 1.0>C2/C1≧0.43, where C2 is the distance from the second member side surface of one member to the tip of the second fin in the facing direction, and the first member and the second member, the value obtained by subtracting C2 from C1 is larger than the amount of deviation of the center of the first member with respect to the center of the second member in the facing direction, The distance in the facing direction from the surface of the first member side of the two members to the tip of the second fin is C3, and the distance from the surface of the second member on the first member side to the lower pressure side than the second fin is C3. C3 is larger than C2, and C4 is larger than C1, where C4 is the distance to the tip of the first fin in the opposing direction.

According to the present invention, the distance C1 in the opposing direction from the surface of the first member on the second member side to the tip of the first fin on the lower pressure side than the second fin, and the distance C1 from the surface of the first member on the second member side The distance C2 in the opposing direction to the tip of the second fin satisfies 1.0>C2/C1≧0.43. Since C2/C1 is less than 1.0, it becomes difficult for the first fins to come into contact with the second fins when assembling the first member and the second member when assembling the rotary machine. Further, since the value obtained by subtracting C2 from C1 is larger than the amount of deviation of the center of the first member in the opposing direction with respect to the center of the second member at the time of assembly, the first member and the second member are assembled. At this time, the contact of the first fin with the second fin is suppressed. This makes it easy to assemble the rotary machine.

In addition, the fluid flowing through the gap between the first fin, which is on the higher pressure side than the second fin, and the first member collides with the second fin, changes the flow direction toward the second member, and moves the second fin. While detouring, it flows toward the gap between the first fin on the lower pressure side than the second fin and the first member. At this time, part of the flow splits to form a whirlpool and swirl in the space between the adjacent first fins. Due to this swirl, the main stream of the flow is pressed against the first member and compressed when flowing through the gap between the first fin on the low pressure side and the first member. As a result, the flow resistance of the main stream increases, so the amount of leakage is greatly reduced. In order to reduce the amount of flow that blows through the gap between the first fin and the second fin, it is necessary to increase the value of C2/C1. If C2/C1 is 0.43 or more, the effect of reducing the amount of leakage can be made equivalent to the case where C2/C1 is 1, which is the maximum.

As described above, it is possible to reduce the amount of leakage while ensuring ease of assembly.

FIG. 4 is a cross-sectional view of a labyrinth seal; It is a figure which shows the result of numerical analysis. It is a sectional view of the labyrinth seal in the 1st modification. It is a sectional view of the labyrinth seal in the 2nd modification. It is a sectional view of a labyrinth seal in the 3rd modification. It is a sectional view of a labyrinth seal in the 4th modification.

Preferred embodiments of the present invention will be described below with reference to the drawings.

(Configuration of rotating machine)
A labyrinth seal according to an embodiment of the invention is provided in a rotating machine. A rotating machine is, for example, a compressor or an expander. In this embodiment, the rotary machine is a turbocompressor.

As shown in FIG. 1, which is a cross-sectional view of the labyrinth seal 1, the rotary machine 10 has a rotating body (first member) 11 and a stationary body (second member) 12. As shown in FIG. The stationary body 12 faces the rotating body 11 . Hereinafter, the direction in which the rotating body 11 and the stationary body 12 face each other will be referred to as a facing direction A. As shown in FIG.

The rotating body 11 is arranged inside the stationary body 12 and rotates around the rotation axis, which is the central axis. The rotating body 11 is, for example, an impeller of a turbocompressor or a turboturbine.

The stationary body 12 is, for example, a casing. Note that the stationary body 12 may be a member that is arranged in a casing and fixed to the casing. FIG. 1 shows the structure of the rotating shaft of the impeller and the surrounding casing when the rotating body 11 is the impeller and the stationary body 12 is the casing.

A gap is formed between the rotating body 11 and the stationary body 12 so that the fluid flows from the high pressure side on the left side of the drawing to the low pressure side on the right side of the drawing. Hereinafter, the direction in which the fluid flows will be referred to as the flow direction B. The flow direction B is perpendicular to the counter direction A.

(Structure of labyrinth seal)
The labyrinth seal 1 has first fins 2 and second fins 3 . The first fin 2 extends from the surface of the stationary body 12 on the side of the rotating body 11 toward the rotating body 11 . That is, the first fin 2 is provided on a portion of the stationary body 12 facing the rotating body 11 . The second fin 3 extends from the surface of the rotating body 11 on the stationary body 12 side toward the stationary body 12 . That is, the second fins 3 are provided on a portion of the rotating body 11 facing the stationary body 12 .

In this embodiment, two first fins 2 are provided side by side along the flow direction B. As shown in FIG. The second fins 3 are arranged between adjacent first fins 2 . Hereinafter, the first fin 2 on the high pressure side (left side in the drawing) as viewed from the second fin 3 is referred to as the high pressure side fin 2a, and the first fin 2 on the low pressure side (right side in the drawing) as viewed from the second fin 3 is referred to as the low pressure side fin. 2b.

Here, the distance in the facing direction A from the surface of the rotating body 11 on the stationary body 12 side to the tip of the low pressure side fin 2b is C1, and the distance from the surface of the rotating body 11 on the stationary body 12 side to the tip of the second fin 3 is C1. Let the distance in the facing direction A be C2. At this time, C1 and C2 satisfy the following relationship.
1.0>C2/C1≧0.43

When assembling the rotating machine 10 , the rotating body 11 is assembled along the flow direction B with respect to the stationary body 12 . The assembly direction of the rotor 11 may be the same as the flow direction B, or may be opposite to the flow direction B. Further, when assembling the rotating machine 10, the stationary body 12 may be assembled with the rotating body 11 in the same direction as the flow direction B or along the opposite direction. In the following description, it is assumed that the stationary body 12 is attached to the rotating body 11 along the flow direction B. As shown in FIG.

Since C2/C1 is less than 1.0, when the stationary body 12 is assembled to the rotating body 11 along the flow direction B during the assembly of the rotating machine 10, the first fin 2 is attached to the second fin 3. It becomes difficult to contact.

Here, in this embodiment, a slide bearing or a tilting pad bearing is used as the bearing that supports the rotating body 11 . Therefore, when the rotating body 11 is stopped, the rotating body 11 and the bearing are in contact with each other, and the center of the rotating body 11 is eccentric with respect to the center of the stationary body 12 .

Therefore, the value obtained by subtracting C2 from C1 is set larger than the amount of deviation of the center of the rotating body 11 from the center of the stationary body 12 in the facing direction A at the time of assembly. This prevents the first fins 2 from abutting the second fins 3 when the stationary body 12 is assembled to the rotating body 11 along the flow direction B. As shown in FIG.

Further, as shown in FIG. 1, when the rotating body 11 rotates, the fluid flowing through the gap between the high-pressure side fin 2a and the rotating body 11 collides with the second fin 3, causing the fluid to flow toward the stationary body 12. , and flows toward the gap between the low pressure side fin 2b and the rotor 11 while bypassing the second fin 3. At this time, part of the flow splits to form a whirlpool and swirl in the space between the adjacent first fins 2 . Due to this eddy current, the main flow is pressed against the rotating body 11 and compressed when flowing through the gap between the low-pressure side fin 2b and the rotating body 11 . As a result, the flow resistance of the main stream increases, so the amount of leakage is greatly reduced.

Here, in order to reduce the amount of flow flowing through the gap between the first fin 2 and the second fin 3, it is necessary to increase the value of C2/C1. According to numerical analysis to be described later, when the differential pressure between the inlet and outlet of the gap formed between the rotating body 11 and the stationary body 12 is 100 kPa or more, if C2/C1 is 0.43 or more, , the effect of reducing the amount of leakage can be made equivalent to the case where C2/C1 is 1 at the maximum.

(Numerical analysis)
Next, a numerical analysis of the amount of leakage was performed for a typical fan differential pressure of 500 Pa and a turbo compressor differential pressure of 100 kPa and 1 MPa. Numerical analysis was performed by changing the distance C2 in the opposing direction A from the surface of the rotating body 11 on the stationary body 12 side to the tip of the second fin 3 between 0 and C1. The results are shown in FIG. Each value is normalized by the leakage amount when C2=0.

At a differential pressure of 100 kPa or more, it is recognized that a critical sealing effect is exhibited at a lower limit of 0.43 or more of the ratio of C2 to C1. If C2/C1=0.43, a sufficient space for assembling the stationary body 12 can be secured when assembling the turbo compressor. Therefore, it can be seen that if 1.0>C2/C1≧0.43 is satisfied, the amount of leakage can be reduced while assemblability is ensured.

(First modification)
In addition, as shown in FIG. 3, which is a sectional view of the labyrinth seal 1, the first fin 2 may be inclined from the low pressure side toward the high pressure side.

(Second modification)
Moreover, as shown in FIG. 4, which is a cross-sectional view of the labyrinth seal 1, the first fin 2 may be curved from the low pressure side toward the high pressure side.

(Third modification)
Further, as shown in FIG. 5, which is a cross-sectional view of the labyrinth seal 1, the second fin 3 may be shaped so as to be pointed toward the stationary body 12. As shown in FIG.

(Fourth modification)
Further, as shown in FIG. 5, which is a cross-sectional view of the labyrinth seal 1, the width of the second fin 3 along the flow direction B may be increased.

(Fifth modification)
Also, along the flow direction B, three or more first fins 2 may be arranged side by side. In this case, the second fins 3 are arranged between the adjacent first fins 2 . With such a configuration, when the fluid flows from the gap between the first fin 2 on the highest pressure side and the rotating body 11 to the gap between the first fin 2 on the lowest pressure side and the rotating body 11, the amount of leakage is small. Gradually reduced. Thereby, the amount of leakage can be sufficiently reduced.

(effect)
As described above, according to the labyrinth seal 1 according to the present embodiment, the distance C1 in the facing direction A from the surface of the rotating body 11 on the side of the stationary body 12 to the tip of the low pressure side fin 2b and the distance C1 of the rotating body 11 A distance C2 in the opposing direction A from the surface on the stationary body 12 side to the tip of the second fin 3 satisfies 1.0>C2/C1≧0.43. Since C2/C1 is less than 1.0, when the rotating body 11 and the stationary body 12 are assembled during assembly of the rotary machine 10, more The first fins 2 are less likely to come into contact with the second fins 3 when assembled along the direction. Further, since the value obtained by subtracting C2 from C1 is larger than the amount of deviation of the center of the rotating body 11 from the center of the stationary body 12 in the facing direction A at the time of assembly, the rotating body 11 and the stationary body 12 are separated from each other. When assembling, more specifically, for example, when assembling the stationary body 12 to the rotating body 11 along the flow direction, the contact of the first fins 2 with the second fins 3 is suppressed. Thereby, the rotating machine 10 can be easily assembled.

In addition, the fluid flowing through the gap between the high-pressure side fin 2a and the rotating body 11 collides with the second fin 3, changes the direction of the flow toward the stationary body 12, bypasses the second fin 3, and moves to the low pressure side. It flows toward the gap between the side fin 2b and the rotating body 11. At this time, part of the flow splits to form a whirlpool and swirl in the space between the adjacent first fins 2 . Due to this eddy current, the main flow is pressed against the rotating body 11 and compressed when flowing through the gap between the low-pressure side fin 2b and the rotating body 11 . As a result, the flow resistance of the main stream increases, so the amount of leakage is greatly reduced. In order to reduce the flow rate through the gap between the first fin 2 and the second fin 3, it is necessary to increase the value of C2/C1. Furthermore, when C2/C1 is 0.43 or more, the effect of reducing the amount of leakage can be made equivalent to the case where C2/C1 is 1, which is the maximum.

As described above, it is possible to reduce the amount of leakage while ensuring ease of assembly.

Further, when three or more first fins 2 are arranged side by side along the flow direction B, from the gap between the first fin 2 on the highest pressure side and the rotating body 11, the first fin on the lowest pressure side As the fluid flows across the gap between the 1 fin 2 and the rotating body 11, the amount of leakage is reduced step by step. Thereby, the amount of leakage can be sufficiently reduced.

Although the embodiments of the present invention have been described above, the specific examples are merely illustrated, and the present invention is not particularly limited. Further, the actions and effects described in the embodiments of the invention are merely enumerations of the most suitable actions and effects resulting from the present invention, and the actions and effects of the present invention are described in the embodiments of the invention. are not limited to those listed.

1 labyrinth seal 2 first fin 2a high pressure side fin 2b low pressure side fin 3 second fin 10 rotating machine 11 rotating body (first member)
12 stationary body (second member)

Claims (2)

a first member;
a second member facing the first member;
A labyrinth seal provided in a rotating machine comprising
The first member and the second member are arranged so that the fluid flows from the high-pressure side to the low-pressure side in a flow direction perpendicular to the direction in which the first member and the second member face each other. A gap is formed between
a first fin extending from a surface of the second member on the first member side toward the first member;
a second fin extending from the surface of the first member on the second member side toward the second member;
has
At least two of the first fins are provided side by side along the flow direction,
The second fins are arranged between the adjacent first fins,
The differential pressure between the inlet and outlet of the gap is 100 kPa or more,
The distance in the facing direction from the surface of the first member on the second member side to the tip of the first fin on the lower pressure side than the second fin is C1, and the distance on the second member side of the first member is 1.0>C2/C1≧0.43, where C2 is the distance in the facing direction from the surface to the tip of the second fin, and
The value obtained by subtracting C2 from C1 is larger than the amount of deviation of the center of the first member from the center of the second member in the facing direction when the first member and the second member are assembled. nine,
The distance in the facing direction from the surface of the second member on the first member side to the tip of the second fin is C3, and the pressure from the surface of the second member on the first member side is lower than that of the second fin. A labyrinth seal, wherein C3 is larger than C2 and C4 is larger than C1, where C4 is the distance in the opposite direction to the tip of the first fin on the side. The labyrinth seal according to claim 1, wherein three or more of the first fins are arranged along the flow direction.

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