JP5653801B2 - Rotary shaft seal structure - Google Patents

Description

  The present invention relates to a seal structure for a rotating shaft of a turbine or a compressor.

  In rotating machines such as turbines and compressors, in order to prevent fluid leakage between the high pressure side and the low pressure side, a seal structure is adopted in which a brush seal fixed to the stationary component side is brought into contact with the rotating shaft (rotor) side. ing. For example, in Patent Document 1, a brush seal is pressed against a rotating shaft using a coil spring or a leaf spring to make contact.

JP 2003-004145 A

  In the seal structure using the coil spring or the leaf spring described above, if the pressing force of the brush seal is small, a gap is formed in the seal, leading to a decrease in sealing performance, and if the pressing force is large, the wear of the brush is accelerated, The gap may become large.

  Therefore, as for the spring of the seal structure described above, while the spring displacement is small, the pressing force against the displacement is linear, and the seal is firmly pressed against the rotating shaft, but after the seal contacts with a certain amount of pressing force, As described above, a spring having nonlinearity that does not increase the pressing force is desirable. For example, when ideal characteristics are shown in FIG. 12, in the region of 0 to x0 where the spring displacement x is small, the pressing force F changes linearly from 0 to F0, and when the spring displacement x exceeds x0, the spring displacement Even if x increases, the pressing force F does not increase. For example, a nonlinear characteristic that is constant at the pressing force F0 is desirable. The pressing force F0 in this case is a minimum pressing force that generates a contact force that can withstand the differential pressure.

  Further, in the seal structure using the above-described coil spring or leaf spring, the spring characteristic is that the pressing force changes only linearly with respect to the amount of spring displacement, and the spring characteristic depends on the operating condition (starting up / during rated operation). The characteristics could not be changed. However, it is also desired to change the spring characteristics according to the operating conditions.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a seal structure for a rotating shaft using a spring whose characteristics are changed in accordance with the amount of displacement and operating conditions.

The seal structure of the rotating shaft according to the first invention for solving the above problem is as follows.
A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
A disc spring and a coil spring are connected in series to form a spring structure, and the spring structure is disposed between the inner peripheral surface of the groove and the outer peripheral surface of each segment, and the segment is rotated. It is characterized by being pressed against the shaft side.

The seal structure of the rotating shaft according to the second invention for solving the above problem is as follows:
In the rotary shaft seal structure according to the first invention,
A plurality of the disc springs are stacked.

The seal structure of the rotating shaft according to the third invention for solving the above-mentioned problems is as follows.
A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
The opening portion of the U-shaped cross section has an annular shape that is in contact with the inner peripheral surface of the groove portion, and an annular member that is elastically deformed so that the opening portion expands is disposed, and the inner peripheral surface of the annular member and each of the above-mentioned A coil spring is connected to the outer peripheral surface of the segment to constitute a spring structure, and the segment is pressed against the rotating shaft side.

The seal structure of the rotating shaft according to the fourth invention for solving the above-mentioned problems is as follows.
In the rotary shaft seal structure according to the third invention,
The both side surfaces of the annular member are shaped to expand toward the opening.

A seal structure for a rotating shaft according to a fifth invention for solving the above-described problems is as follows.
In the seal structure of the rotating shaft according to the third or fourth invention,
An inner peripheral surface of the groove portion that is in contact with the opening portion of the annular member is inclined so that both side surfaces of the annular member expand outward.

The seal structure of the rotating shaft according to the sixth invention for solving the above-described problems is as follows.
A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
In order from the outer peripheral side, a coil spring, an intermediate block, and other coil springs are connected in series to form a spring structure, and the spring structure is disposed between the inner peripheral surface of the groove and the outer peripheral surface of each segment. In addition, before and during startup, there is a gap between the intermediate block and during operation, contact portions that come into contact with the intermediate block by thermal expansion are provided on both side surfaces of the groove, and before startup and during startup. The segment is pressed against the rotating shaft by a coil spring and another coil spring, and the segment is pressed against the rotating shaft by another coil spring during operation.

  According to the present invention, since the non-linearity required for the spring can be secured in the seal structure of the rotating shaft, the performance of the fluid seal is improved, and as a result, the reliability is improved and the turbine efficiency and the compression efficiency are improved. become.

  Further, according to the present invention, in the seal structure of the rotating shaft, the spring characteristics can be changed according to the operating condition. Therefore, even if there is runout of the rotating shaft, thermal expansion difference at the time of transient, eccentricity, etc., the performance of the fluid seal is maintained, and as a result, reliability is improved and turbine efficiency and compression efficiency are improved.

(A) is an axial sectional view showing an example (Example 1) of an embodiment of a seal structure of a rotating shaft according to the present invention, and (b) is a sectional view taken along line AA in (a). It is. (A) is a graph of the spring characteristics in the seal structure shown in FIG. 1, (b) is a schematic diagram showing the spring structure at F1 in (a), and (c) is F2 in (a). It is the schematic which shows the spring structure in. It is the schematic which shows the modification of the spring structure of the seal structure shown in FIG. It is the schematic which shows the spring structure as another example (Example 2) of embodiment of the sealing structure of the rotating shaft which concerns on this invention. It is a graph of the spring characteristic in the seal structure shown in FIG. It is the schematic which shows the modification of the spring structure of the seal structure shown in FIG. It is the schematic which shows the spring structure as another example (Example 3) of embodiment of the sealing structure of the rotating shaft which concerns on this invention. It is a graph of the spring characteristic in the seal structure shown in FIG. It is the schematic which shows the modification of the spring structure of the seal structure shown in FIG. (A) is an axial sectional view showing another example (Example 4) of the embodiment of the seal structure of the rotating shaft according to the present invention, and (b) is a view taken along line BB in (a). It is sectional drawing. It is the schematic which shows the modification of the spring structure of the seal structure shown in FIG. It is a graph which shows the characteristic ideal for the spring of a seal structure.

  Hereinafter, some embodiments of the seal structure of the rotating shaft according to the present invention will be described with reference to FIGS. Here, as an example, the seal structure of the rotary shaft of the gas turbine is illustrated, but the present invention can also be applied as a seal structure of the rotary shaft of a compressor or the like.

Example 1
Fig.1 (a) is an axial sectional view which shows the seal structure of a present Example, FIG.1 (b) is an AA arrow directional cross-sectional view of Fig.1 (a). 2A is a graph of spring characteristics in the seal structure shown in FIG. 1, and FIG. 2B is a schematic diagram showing the spring structure at F1 in FIG. 2A. (C) is the schematic which shows the spring structure in F2 of Fig.2 (a). FIG. 3 is a schematic view showing a modification of the spring structure of this embodiment.

  The rotating shaft 1 of the gas turbine is supported by a bearing (not shown), and a seal holder 2 (housing) is provided so as to surround the outer periphery of the rotating shaft 1 at a portion where sealing is performed. The seal holder 2 is provided in a casing (not shown) of the gas turbine, and a seal groove 3 (groove portion) is formed in an annular shape on the inner peripheral side (rotary shaft 1 side) of the seal holder 2. The seal structure 10 of the present embodiment is incorporated in the seal groove 3.

  In the seal groove 3, a convex portion 4 having a convex cross-sectional shape is formed on the opposite side surface 3 a. In the seal segment 11 of the seal structure 10, a concave shape portion 12 having a concave cross section is formed at a position facing the convex shape portion 4, and the convex shape portion 4 and the concave shape portion 12 come into contact with each other. The surface 5 is engaged. In addition, you may engage the convex-shaped part 4 and the concave-shaped part 12 as a mutually reverse shape.

  In the seal structure 10, the seal segment 11 is divided into four arc shapes, for example, as shown in FIG. 1B, and is arranged around the rotation shaft 1 in an annular shape. Note that the number of divisions of the seal segment 11 is not limited to four, and the number of divisions may be increased or decreased as appropriate in consideration of processability, ease of assembly, ease of maintenance, and the like. This is the same in the embodiments described later.

  A brush 12 (brush seal) in which a large number of fine metal wires are bundled is welded to the inner peripheral surface of each seal segment 11, and the tip of the brush 12 has a certain angle to the outer periphery of the rotary shaft 1. In contact with the surface. When the operation of the gas turbine is started and the rotary shaft 1 rotates, the working fluid tends to flow from the high pressure side H to the low pressure side L. Since it is partitioned, the flow of the working fluid is blocked and the airtightness between the two is maintained.

  At this time, conventionally, the brush seal is pressed against the rotating shaft by using a coil spring or a leaf spring, and in this case, as described above, if the pressing force of the brush seal is small, there is a gap in the seal. If it is possible to reduce the sealing performance and the pressing force is large, the wear of the brush is accelerated and the gap may be increased.

  Therefore, as a spring characteristic of the seal structure, as long as the spring displacement is small, the pressing force against the displacement is linear and the brush is firmly pressed against the rotating shaft, but after the brush contacts with a certain amount of pressing force, it is more than that It is desirable to have non-linearity that does not increase the pressing force.

  Therefore, in this embodiment, a spring structure having nonlinearity is used by adopting the following configuration.

  Specifically, the annular member 13 is arranged so that the opening portion of the U-shaped cross section is in contact with the inner peripheral surface 3 b of the seal groove 3, and the inner peripheral surface of the annular member 13 and the outer periphery of each seal segment 11. A coil spring 14 is provided for each seal segment 11 between the surfaces. The annular member 13 is made of, for example, a metal plate, and is not fixed to the inner peripheral surface 3b of the seal groove 3 but is in contact with the annular member 13. Therefore, when the pressing force F acts on the annular member 13, as shown in FIG. 2C described later, the elastic member itself is elastically deformed and a dynamic frictional force μ is generated between the inner peripheral surface 3 b of the seal groove 3. Thus, the spring structure, that is, the combination of the annular member 13 and the coil spring 14 has non-linearity.

  Here, the displacement (deformation) of the annular member 13 and the coil spring 14 will be further described with reference to FIG.

  In this embodiment, the spring structure is composed of an annular member 13 and a coil spring 14. Therefore, in the region where the displacement x is small, that is, in F1 in the graph of FIG. 2A, there is almost no displacement (deformation) of the annular member 13 and the elastic force of the coil spring 14 as shown in FIG. Mainly acts, and the pressing force F1 with respect to the displacement x has linearity.

  On the other hand, in the region where the displacement x is large, that is, in F2 in the graph of FIG. 2A, as shown in FIG. 2C, the annular member 13 bends, and the maximum static friction of the contact portion with the inner peripheral surface 3b. After the shearing force exceeding the force is generated, the both side surfaces of the annular member 13 are displaced (deformed) so as to spread outward, but the pressing force F2 with respect to the displacement x is linear due to the relationship with the dynamic friction force μ. The gradient becomes gentler than the pressing force F1. As a result, the spring structure composed of the annular member 13 and the coil spring 14 has nonlinearity with respect to the displacement x.

  Therefore, while the displacement x is small, the pressing force F1 with respect to the displacement x is linear due to the elastic force of the coil spring 14 and the brush 12 is firmly pressed against the rotating shaft 1. Contact can be ensured and sealing performance is maintained. Further, when the displacement x becomes larger than the predetermined displacement x0 and the brush 12 comes into contact with the predetermined pressing force F0, the pressing force F2 gradually increases by the elastic force of the annular member 13 and the coil spring 14 thereafter. Thus, the wear of the brush can be prevented, the gap can be prevented from being enlarged, and the deterioration of the sealing performance can be suppressed.

  For example, when the rotating shaft 1 fluctuates in a direction perpendicular to the axial direction (when the shaft is shaken or decentered), the seal segment 11 hardly moves due to the elastic force of the annular member 13 and the coil spring 14, and the fluctuation is reduced by the brush 12. Therefore, the gap is not generated, and the working fluid hardly leaks at the portion where the brush 12 is in contact with the rotating shaft 1.

  In addition, since the seal segment 11 is also pressed against the contact surface 5 of the convex portion 4, the adhesiveness between the concave portion 12 and the convex portion 4 can be maintained, and the leaking operation is performed through the contact surface 5. The fluid is almost gone.

  Instead of the annular member 13, an annular member 15 as shown in FIG. 3, that is, a shape whose both side surfaces expand toward the opening portion may be used.

(Example 2)
FIG. 4 is a schematic view showing a spring structure of the seal structure of the present embodiment. FIG. 5 is a graph of spring characteristics in the seal structure shown in FIG. FIG. 6 is a schematic view showing a modification of the spring structure of this embodiment. In addition, the same code | symbol is attached | subjected to the member equivalent to Example 1 here.

  The present embodiment is substantially the same as the structure shown in FIG. 1 of the first embodiment, but the spring structure having a non-linearity is used by making the structure of the spring structure different from that of the first embodiment. I have to.

  Specifically, as shown in FIG. 4, a disc spring 21 and a coil spring 14 connected in series between the inner peripheral surface 3 b of the seal groove 3 and the outer peripheral surface of each seal segment 11 are provided for each seal segment 11. Provided. The disc spring 21 is made of metal, for example. Normally, a disc spring has a non-linear spring characteristic, but has a drawback that its allowable displacement is small. Therefore, in the present embodiment, the disc spring 21 and the coil spring 14 are connected in series to make use of a non-linear spring characteristic and to compensate for the disadvantage that the allowable displacement is small. Specifically, FIG. As shown in the figure, by adding the characteristics of the disc spring 21 and the characteristics of the coil spring 14, nonlinearity is obtained.

  Therefore, while the displacement x is small, the pressing force F with respect to the displacement x is substantially linear, and the brush 12 is firmly pressed against the rotating shaft 1 to maintain the sealing performance. On the other hand, when the displacement x becomes larger than the predetermined displacement and the brush 12 comes into contact with the predetermined pressing force, thereafter, the pressing force F does not increase any more, preventing the brush 12 from being worn and increasing the gap. It is possible to prevent the deterioration of the sealing performance.

  In addition, as shown in FIG. 6, the part of the disc spring 21 in the present embodiment may be configured by further stacking a plurality of disc springs 21. In that case, from the relationship between the deflection and the pressing force, as shown in FIG. 6, the disc springs 21 may be alternately stacked in the opposite direction (referred to as a series assembly), or the disc springs 21 are stacked in the same direction. (It is also called a parallel set.) A series set and a parallel set may be combined.

Example 3
FIG. 7 is a schematic view showing the spring structure of the seal structure of the present embodiment. FIG. 8 is a graph of spring characteristics in the seal structure shown in FIG. FIG. 9 is a schematic view showing a modification of the spring structure of this embodiment. In this case as well, the same members as those in the first embodiment are denoted by the same reference numerals.

  Although the present embodiment also has a configuration that is substantially equivalent to the configuration shown in FIG. 1 of the first embodiment, the configuration of the inner peripheral surface 3b that contacts the spring structure is different from that of the first embodiment.

  In the first embodiment, the inner peripheral surface 3b with which the annular member 13 contacts is a flat surface. However, in this embodiment, as shown in FIG. 7, a trapezoidal cross-section is provided on the inner peripheral surface 3b of the seal groove 3. A portion 6 is provided so that the annular member 13 is in contact with the slope 6 a of the protruding portion 6. Thereby, both side surfaces of the annular member 13 are expanded in the outer direction with a small displacement x as compared with the first embodiment.

  In this way, the portion in contact with the annular member 13 is the inclined surface 6a. For example, by changing the inclination angle θ of the inclined surface 6a, the shear force generated by the deflection of the annular member 13 causes the maximum static frictional force with the inclined surface 6a. It is possible to adjust the displacement point that exceeds, that is, the change point to nonlinearity. For example, as shown in the graph of FIG. 8, in Example 1, when the displacement x0 becomes larger, the pressing force F gradually increases from F0. However, as in this example, the annular member 13 comes into contact. Assuming that the portion to be inclined is the inclined surface 6a having the inclination angle θ, the pressing force F gradually increases from F3 at a displacement x3 smaller than the displacement x0. Thus, the change point (displacement x) at which the gradient of the pressing force F becomes gentle can be adjusted by changing the inclination angle θ of the inclined surface 6a.

  Therefore, while the displacement x is small, the pressing force F with respect to the displacement x is linear, and the brush 12 is firmly pressed against the rotating shaft, and the sealing performance is maintained. On the other hand, when the displacement x becomes larger than the predetermined displacement and the brush 12 comes into contact with the predetermined pressing force, thereafter, the pressing force F does not increase any more, preventing the brush 12 from being worn and increasing the gap. It is possible to prevent the deterioration of the sealing performance.

  In addition, it replaces with the protrusion part 6 of the trapezoidal cross section in a present Example, and as shown in FIG. 9, you may use the protrusion part 7 (slope 7a) of a circular arc cross section, and the same effect can be acquired.

Example 4
Fig.10 (a) is an axial sectional view which shows the seal structure of a present Example, FIG.10 (b) is a BB arrow sectional drawing of Fig.10 (a). FIG. 11 is an axial sectional view showing a modification of the spring structure of this embodiment. In this case as well, the same members as those in the first embodiment are denoted by the same reference numerals.

  The present embodiment also has a configuration that is substantially equivalent to the configuration shown in FIG. 1 of the first embodiment. However, by changing the configuration of the spring structure from that of the first embodiment, the operating status of the gas turbine (starting / A spring structure with characteristics corresponding to the rated operation) is used.

  The rotating shaft 1 of the gas turbine is supported by a bearing (not shown), and a seal holder 2 (housing) is provided so as to surround the outer periphery of the rotating shaft 1 at a portion where sealing is performed. The seal holder 2 is provided in a casing (not shown) of the gas turbine, and a seal groove 3 (groove portion) is formed in an annular shape on the inner peripheral side (rotary shaft 1 side) of the seal holder 2. Inside this seal groove 3, the seal structure 30 of this embodiment is incorporated.

  In the seal groove 3, a convex portion 4 having a convex cross-sectional shape is formed on the opposite side surface 3 a, but in the seal segment 31 of the seal structure 30, the outer peripheral side is between the convex portions 4. Unlike the first embodiment, the seal segment 31 does not have a portion that engages with the seal groove 3 (convex shape portion 4). Therefore, in this embodiment, as shown in FIG. 10A, the labyrinth seal 36 is provided by alternately arranging seal fins on the convex portion 4 and the seal segment 31. In such a labyrinth seal 36, the path length is increased by alternately providing seal fins, and resistance due to bending of the flow is added, so that the amount of leakage of the working fluid can be reduced.

  In the seal structure 30, for example, as shown in FIG. 10B, the seal segment 31 is divided into four arc shapes and is arranged around the rotation shaft 1 in an annular shape. Note that the number of divisions of the seal segment 31 is not limited to four, and the number of divisions may be increased or decreased as appropriate in consideration of processability, ease of assembly, ease of maintenance, and the like.

  A brush 12 (brush seal) in which a large number of fine metal wires are bundled is welded to the inner peripheral surface of each seal segment 31, and the tip of the brush 12 has a certain angle to the outer periphery of the rotary shaft 1. In contact with the surface. When the operation of the gas turbine is started and the rotary shaft 1 rotates, the working fluid tends to flow from the high pressure side H to the low pressure side L. Since it is partitioned, the flow of the working fluid is blocked and the airtightness between the two is maintained.

  At this time, conventionally, the brush seal is pressed against the rotating shaft by using a coil spring or a leaf spring, and in this case, as described above, the spring characteristic is the pressing force against the spring displacement amount. However, the spring characteristics could not be changed depending on the operating conditions (starting up / during rated operation).

  Therefore, it is desirable that the spring characteristics of the seal structure have a low spring constant during startup (in the case of a gas turbine, during temperature rise) and a high spring constant during rated operation.

  Therefore, in this embodiment, the following structure is used to use a spring structure in which the spring characteristics are changed according to the operating condition.

  Specifically, as shown in FIGS. 10A and 10B, a spring structure is provided between the outer peripheral surface of the seal segment 31 and the inner peripheral surface 3 b of the seal groove 3. The coil spring 32, the intermediate block 33, and the coil spring 34 are connected in series in this order from the outer peripheral side, and the contact portion 35 that contacts the intermediate block 33 and generates friction under a predetermined condition is provided as a seal groove. 3 is provided on each of the three side surfaces 3a.

  More specifically, a gap is formed between the intermediate block 33 and the contact portion 35 during stoppage to start-up (temperature increase) so that the intermediate block 33 and the contact portion 35 do not come into contact with each other. In this case, since the intermediate block 33 is not constrained, for example, when the spring coefficients of the coil spring 32 and the coil spring 34 are both “k”, the spring coefficient of the entire spring structure is “½k”.

  On the other hand, during rated operation, the intermediate block 33 and the contact portion 35 are brought into contact with each other by eliminating the gap that has occurred during the stop-starting operation due to the thermal expansion of the intermediate block 33 and the contact portion 35 due to the temperature rise. . In this case, since the intermediate block 33 is constrained by friction, for example, when the spring coefficients of the coil spring 32 and the coil spring 34 are both “k”, only the coil spring 34 functions, and the spring coefficient of the entire spring structure is “ k ".

  In this manner, the spring characteristics of the seal structure 30 are such that the spring constant is weak during startup (during temperature rise) and the spring constant is strong during rated operation. This characteristic can be adjusted by appropriately setting the heat capacity and the linear expansion coefficient of the intermediate block 33 and the contact portion 35. As a result, the fluid seal performance is maintained even if there is a swing of the rotating shaft 1, a thermal expansion difference at the time of transient, eccentricity, etc., and as a result, reliability is improved and turbine efficiency and compression efficiency are improved. Become.

  In addition, the contact part with the intermediate block 33 of the contact part 35 in a present Example is good also as a shape as shown in FIG. Specifically, the non-contact surface 35a and the contact surface 35b are provided along the direction in which the intermediate block 33 is displaced. In this case, in the initial stage of displacement, the intermediate block 33 is located in the range of the non-contact surface 35a, so that it does not contact the contact portion 35. On the other hand, when the intermediate block 33 is displaced to some extent, the intermediate block 33 is positioned in the range of the contact surface 35b, so that it comes into contact with the contact portion 35 and restrains the intermediate block 33. That is, by appropriately setting the positions and ranges of the non-contact surface 35a and the contact surface 35b, it is possible to adjust the region where the friction by the contact portion 35 is applied. Further, when the displacement becomes excessive, the intermediate block 33 may be restrained from further movement using a stopper portion 35c provided on the outer peripheral side of the contact portion 35.

  In addition, a present Example uses a spring structure of Example 1- Example 3 mentioned above for the part of the coil spring 34, and while giving a non-linearity with respect to a displacement amount, according to an operating condition, a spring characteristic is provided. It can also be configured to change.

  The seal structure of the rotating shaft according to the present invention is suitable for sealing between a high pressure side and a low pressure side in a rotary machine such as a turbine or a compressor.

3 Seal groove 6, 7 Protruding portion 10, 30 Seal structure 11, 31 Seal segment 13, 15 Annular member 14, 32, 34 Coil spring 15 Brush seal 21 Countersunk screw 33 Intermediate block

Claims (6)

A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
A disc spring and a coil spring are connected in series to form a spring structure, and the spring structure is disposed between the inner peripheral surface of the groove and the outer peripheral surface of each segment, and the segment is rotated. A rotary shaft seal structure characterized by being pressed against the shaft side. The rotary shaft seal structure according to claim 1,
A rotating shaft seal structure, wherein a plurality of disc springs are stacked. A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
The opening portion of the U-shaped cross section has an annular shape that is in contact with the inner peripheral surface of the groove portion, and an annular member that is elastically deformed so that the opening portion expands is disposed, and the inner peripheral surface of the annular member and each of the above-mentioned A rotating shaft sealing structure characterized in that a coil spring is connected to the outer peripheral surface of a segment to constitute a spring structure, and the segment is pressed against the rotating shaft side. In the seal structure of the rotating shaft according to claim 3,
A seal structure for a rotating shaft, wherein both side surfaces of the annular member have a shape expanded toward the opening. In the seal structure of the rotating shaft according to claim 3 or claim 4,
A seal structure for a rotating shaft, wherein an inner peripheral surface of the groove portion that is in contact with the opening portion of the annular member is inclined so that both side surfaces of the annular member expand outward. A groove provided in an annular shape on the inner peripheral side of the casing around the rotation axis;
A plurality of arc-shaped segments arranged annularly in the groove;
A brush provided on the inner peripheral side of each of the segments, and in contact with the outer peripheral surface of the rotary shaft;
In the seal structure of the rotary shaft that seals the rotary shaft with the brush,
In order from the outer peripheral side, a coil spring, an intermediate block, and other coil springs are connected in series to form a spring structure, and the spring structure is disposed between the inner peripheral surface of the groove and the outer peripheral surface of each segment. In addition, before and during startup, there is a gap between the intermediate block and during operation, contact portions that come into contact with the intermediate block by thermal expansion are provided on both side surfaces of the groove, and before startup and during startup. The segment is pressed against the rotating shaft side by a coil spring and another coil spring, and the segment is pressed against the rotating shaft side by another coil spring during operation. Shaft seal structure.

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