JP2021071185A - Labyrinth seal - Google Patents

Abstract

To provide a labyrinth seal capable of reducing a leakage amount while securing assemblability.SOLUTION: A labyrinth seal has first fins 2 extended to a rotor 11 from a surface at a rotor 11 side, of a stationary body 12, and second fins 3 extended to the stationary body from a surface at a stationary body side, of the rotor, at least two first fins are arranged along a flowing direction B, the second fins are respectively disposed between the adjacent first fins, and pressure difference between an inlet and an outlet of a clearance formed between the rotor and the stationary body is 100 kPa or more. When a distance from a surface at a stationary body side, of the rotor to a tip of a fin 2b at a low pressure-side with respect to the second fin in an opposite direction A is C1, and a distance from the surface at the stationary body side, of the rotor to a tip of the second fin in the opposite direction A is C2, 1.0>C2/C1≥0.43 is satisfied. A value obtained by subtracting C2 from C1 is more than a deviation amount of a center of the rotor from a center of the stationary body in the opposite direction A, in assembling the rotor and the stationary body.SELECTED DRAWING: Figure 1

Description

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

Patent Document 1 discloses a fan sealing device. In this sealing device, a staggered labyrinth seal portion is formed by a squeezing piece projecting from the ring and a reverse squeezing piece projecting from a tubular portion of a shroud arranged facing the ring. The distance C1 from the inner peripheral surface of the tubular portion to the tip of the diaphragm piece and the distance C2 from the inner peripheral surface of the tubular portion to the tip of the reverse diaphragm piece satisfy the relationship of C2 ≦ C1. Thereby, when assembling the sealing device, the ring can be easily attached to the tubular body of the shroud from the axial direction.

JP-A-2002-106488

In a typical fan, a rolling bearing is used to support the rotating shaft. In this case, since the axial center of the rotor and the center of the seal stator coincide with each other, as in Patent Document 1, if the relationship of C2 ≤ C1 is satisfied, assembly from the axial direction is possible.

On the other hand, in turbomachinery, slide bearings and tilting pad bearings are used for bearings. In this case, the center of the rotor is designed to be located at the center of the seal stator during steady operation in consideration of the oil film thickness and the inclination of the pad. The seal stator is assembled to the rotor when the rotor is stopped. However, when the rotor is stopped, the rotor and the bearing are in contact with each other, so that 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 of C2 ≤ C1 is satisfied, if the amount of eccentricity of the rotor is larger than the value obtained by subtracting C2 from C1, assembly from the axial direction becomes impossible. ..

Therefore, in order to ensure the ease of assembly, it is conceivable to set C1> C2. However, as the value of C2 becomes smaller than the value of C1, the width of the atrium passage formed between the diaphragm piece and the reverse diaphragm piece becomes wider, and the amount of leakage increases.

An object of the present invention is to provide a labyrinth seal capable of reducing the amount of leakage while ensuring assembling property.

The present invention is a labyrinth seal provided on a rotating machine including a first member and a second member facing the first member, in a direction in which 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 orthogonal to the opposite direction, and the second member said. It has a first fin extending from the surface on the first member side toward the first member, and a second fin extending from the surface on the second member side 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 arranged between the adjacent first fins, respectively, and the inlet and the outlet of the gap are provided. The differential pressure is 100 kPa or more, and the distance 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 in the opposite direction is C1, the first. When the distance from the surface of one member on the second member side to the tip of the second fin in the opposite direction is C2, 1.0> C2 / C1 ≧ 0.43 is satisfied and the first member is satisfied. When assembling the second 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 opposite direction. To do.

According to the present invention, the distance C1 in the opposite 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 from the surface of the first member on the second member side. The distance C2 in the opposite 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 fin to come into contact with the second fin when assembling the first member and the second member at the time of 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 opposite 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 that time, the contact of the first fin with the second fin is suppressed. As a result, the rotating machine can be easily assembled.

Further, the fluid flowing through the gap between the first fin on the higher pressure side than the second fin and the first member collides with the second fin to change the direction of the flow toward the second member and make the second fin. While detouring, the fluid flows toward the gap between the first fin on the lower pressure side than the second fin and the first member. At this time, a part of the flow is divided into a vortex and swirls in the space between the adjacent first fins. Due to this eddy current, 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 mainstream is increased, so that the amount of leakage is significantly reduced. Then, in order to reduce the flow rate that blows through the gap between the first fin and the second fin, it is necessary to increase the value of C2 / C1, but when the differential pressure between the inlet and outlet of the gap is 100 kPa or more, When C2 / C1 is 0.43 or more, the effect of reducing the leakage amount can be made equivalent to the case where C2 / C1 is the maximum of 1.

As described above, the amount of leakage can be reduced while ensuring the ease of assembly.

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

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Structure of rotating machine)
The labyrinth seal according to the embodiment of the present invention is provided on the rotating machine. The rotating machine is, for example, a compressor or an expander. In this embodiment, the rotating machine is a turbo compressor.

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

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

The stationary body 12 is, for example, a casing. The stationary body 12 may be a member arranged in the casing and fixed to the casing. FIG. 1 shows the structure of the rotating shaft of the impeller and the casing around the impeller when the rotating body 11 is an impeller and the stationary body 12 is a 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 in the figure toward the low pressure side on the right side in the figure. Hereinafter, the direction in which the fluid flows is referred to as a flow direction B. The flow direction B is orthogonal to the opposite direction A.

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

In the present embodiment, the two first fins 2 are provided side by side along the flow direction B. The second fin 3 is arranged between the adjacent first fins 2. Hereinafter, the first fin 2 on the high pressure side (left side in the figure) when viewed from the second fin 3 is the high pressure side fin 2a, and the first fin 2 on the low pressure side (right side in the figure) when viewed from the second fin 3 is the low pressure side fin. It is called 2b.

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

At the time of assembling the rotating machine 10, the rotating body 11 is assembled to the stationary body 12 along the flow direction B. The assembling direction of the rotating body 11 may be the same as the flow direction B or the opposite direction to the flow direction B. Further, when assembling the rotating machine 10, the stationary body 12 may be assembled to the rotating body 11 in the same direction as the flow direction B or in the opposite direction. Hereinafter, the case where the stationary body 12 is assembled to the rotating body 11 along the flow direction B will be described.

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 at the time of assembling the rotating machine 10, the first fin 2 is attached to the second fin 3. It becomes difficult to contact.

Here, in the present embodiment, a slide bearing or a tilting pad bearing is used for 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 larger than the amount of deviation of the center of the rotating body 11 with respect to the center of the stationary body 12 in the opposite direction A at the time of assembly. As a result, when the stationary body 12 is assembled to the rotating body 11 along the flow direction B, the first fin 2 is prevented from coming into contact with the second fin 3.

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 and thus flows toward the stationary body 12. The fluid flows toward the gap between the low-pressure side fin 2b and the rotating body 11 while bypassing the second fin 3. At this time, a part of the flow is divided into a vortex and swirls in the space between the adjacent first fins 2. Due to this vortex flow, the main stream of the 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 mainstream is increased, so that the amount of leakage is significantly reduced.

Here, in order to reduce the flow rate that blows 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 the numerical analysis described later, when the differential pressure between the inlet and the 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 the maximum of 1.

(Numerical analysis)
Next, a numerical analysis of the amount of leakage was performed when the differential pressure of a general fan was 500 Pa and the differential pressure of a turbo compressor was 100 kPa and 1 MPa. The numerical analysis was performed by changing the distance C2 in the facing 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 result is shown in FIG. Each value is normalized by the amount of leakage at C2 = 0.

At a differential pressure of 100 kPa or more, it is recognized that a critical effect on the sealing effect is exhibited at the lower limit of 0.43 or more of the ratio of C2 to C1. If C2 / C1 = 0.43, a sufficient space can be secured for assembling the stationary body 12 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 ensuring the assembling property.

(First modification)
As shown in FIG. 3, which is a cross-sectional view of the labyrinth seal 1, the first fin 2 may be inclined from the low pressure side to the high pressure side.

(Second modification)
Further, 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 to the high pressure side.

(Third modification example)
Further, as shown in FIG. 5, which is a cross-sectional view of the labyrinth seal 1, the second fin 3 may have a sharp shape toward the stationary body 12.

(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 may be widened along the flow direction B.

(Fifth modification)
Further, three or more first fins 2 may be provided side by side along the flow direction B. 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 large. It is gradually reduced. As a result, 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 stationary body 12 side to the tip of the low pressure side fin 2b and the rotating body 11 The distance C2 in the facing 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 assembling the rotating machine 10 and assembling the rotating body 11 and the stationary body 12, more specifically, for example, the stationary body 12 flows with respect to the rotating body 11. When assembling along the direction, it becomes difficult for the first fin 2 to come into contact with the second fin 3. 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 with respect to the center of the stationary body 12 in the opposite direction A at the time of assembly, the rotating body 11 and the stationary body 12 are combined. More specifically, when assembling the stationary body 12 with respect to the rotating body 11 along the flow direction, it is possible to prevent the first fin 2 from coming into contact with the second fin 3. As a result, the rotary machine 10 can be easily assembled.

Further, the fluid flowing through the gap between the high-pressure side fin 2a and the rotating body 11 collides with the second fin 3 to change the direction of the flow toward the stationary body 12, bypassing the second fin 3 and lower pressure. It flows toward the gap between the side fin 2b and the rotating body 11. At this time, a part of the flow is divided into a vortex and swirls in the space between the adjacent first fins 2. Due to this vortex flow, the main stream of the 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 mainstream is increased, so that the amount of leakage is significantly reduced. Then, in order to reduce the flow rate that blows through the gap between the first fin 2 and the second fin 3, it is necessary to increase the value of C2 / C1, but when the differential pressure between the inlet and the outlet of the gap is 100 kPa or more. In addition, when C2 / C1 is 0.43 or more, the effect of reducing the leakage amount can be made equivalent to the case where C2 / C1 is the maximum of 1.

As described above, the amount of leakage can be reduced while ensuring the ease of assembly.

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

Although the embodiments of the present invention have been described above, only specific examples are illustrated, and the present invention is not particularly limited, and the specific configuration and the like can be appropriately redesigned. In addition, the actions and effects described in the embodiments of the present invention merely list the most preferable actions and effects arising from the present invention, and the actions and effects according to the present invention are described in the embodiments of the present invention. It is not limited to what has been done.

1 Labyrinth seal 2 1st fin 2a High pressure side fin 2b Low pressure side fin 3 2nd fin 10 Rotating machine 11 Rotating body (1st member)
12 Stationary body (second member)

Claims (2)

The first member and
The second member facing the first member and
A labyrinth seal provided on a rotating machine equipped with
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 which is the direction orthogonal to the opposite direction where the first member and the second member face each other. There is a gap between them,
A first fin extending from the surface of the second member on the side of the first member toward the first member,
A second fin extending from the surface of the first member on the side of the second member toward the second member,
Have,
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, respectively.
The differential pressure between the inlet and outlet of the gap is 100 kPa or more.
The distance 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 in the opposite direction is C1, and the distance on the second member side of the first member is C1. When the distance from the surface to the tip of the second fin in the opposite direction is C2, 1.0> C2 / C1 ≧ 0.43 is satisfied, and
When assembling 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 opposite direction. A labyrinth seal that features that. The labyrinth seal according to claim 1, wherein three or more of the first fins are provided side by side along the flow direction.

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