Technical Field
[0001]
The present invention relates to a shaft sealing device that seals an annular space between a rotor and a stator to divide the annular space into a low-pressure region and a high-pressure region, and a rotating machine comprising the same.
Priority is claimed on Japanese Patent Application No. 2011-234825, filed October 26, 2011, the content of which is incorporated herein by reference.
Background Art
[0002]
A shaft sealing device is provided around a rotor in a rotating machine, such as a gas turbine or a steam turbine, in order to reduce the leak amount of a working fluid that flows from a high-pressure side to a low-pressure side. As an example of this shaft sealing device, for example, a shaft sealing device described in the following Patent Document 1 is known.
[0003]
This shaft sealing device includes a housing provided at the stator, and a seal body including multiple thin plate sealing pieces.
In the seal body, the multiple thin plate sealing pieces are stacked with small clearances between each other such that the thickness direction of each thin plate sealing piece is directed to the circumferential direction of the rotor. The respective thin plate sealing pieces are obliquely arranged so that the end portions (tips) of the thin sealing

pieces on a radial inner side are located further toward a forward side in the rotational direction of the rotor than the end portions (rear ends) of the thin sealing pieces on a radial outer side, the rear ends thereof are coupled to each other at the rear ends thereof, and the tips of the thin sealing pieces are free ends.
[0004]
In the shaft sealing device schematically configured in this way, the tip of each thin plate sealing piece comes into contact with the rotor when the rotor remains stationary. If the rotor rotates, the tips of the thin plate sealing pieces are lifted from the outer periphery of the rotor by a dynamic pressure effect produced by the rotation of the rotor, and are brought into non-contact with the rotor. For this reason, in the shaft sealing device, wear of each thin plate sealing piece is reduced, and the service life of a seal becomes long.
[0005]
Additionally, in the above-described mechanism, one axial end portion of the seal body on a fluid low-pressure region side in an axial direction is covered with a low-pressure side plate, and the other axial end portion of the seal body on a fluid high-pressure region side in the axial direction is covered with a high-pressure side plate. Also, the flow of the working fluid to the small clearances between the thin plate sealing pieces is regulated by the low-pressure side plate and the high-pressure side plate.
[0006]
Here, the low-pressure side plate and the high-pressure side plate are usually segmented into a plurality of portions in the circumferential direction and are disposed with segmentation clearances between each other.

Patent Document [0007] [Patent Document 1] Japanese Patent No. 3616016
Summary of the Invention
Problems to be Solved by the Invention
[0008]
Incidentally, in the rotating machine, a swirl flow may be produced in the rotational direction. If the above-described shaft sealing device is applied to a place where the speed of such a swirl flow is fast, due to the swirl flow on the fluid high-pressure region side and an uneven flow in the vicinity of a segmented portion of the high-pressure side plate or the low-pressure side plate, pressure fluctuation may occur in the high-pressure side plate and fluttering may occur in the high-pressure side plate. In this case, the high-pressure side plate may malfunction, for example, in a place including the vicinity of the segmented portion of the high-pressure side plate.
[0009]
The present invention has been made in consideration of such circumstances, and an object thereof is to provide a shaft sealing device that can prevent fluttering, and a rotating machine including the same.
Means for Solving the Problems
[0010]
According to a first aspect of the present invention, a shaft sealing device is provided in an annular space between a rotor and a stator surrounding an outer periphery of the rotor to divide the annular space into a high-pressure region and a low-pressure

region in the direction of an axis of the rotor. The shaft sealing device includes a seal body having a plurality of thin plate sealing pieces that extend from the stator toward a radial inner side of the rotor and are stacked in a circumferential direction of the rotor; a high-pressure side plate that extends from the stator toward the radial inner side so as to run along the high-pressure side of the seal body, and is segmented into a plurality of portions in the circumferential direction; and a rigidity imparting member configured to impart rigidity in the direction of the axis to a portion of a surface of the high-pressure side plate that faces the high-pressure region.
[0011]
In such a shaft sealing device, the high-pressure side plate is provided with the rigidity imparting member. Therefore, the rigidity of the high-pressure side plate in the thickness direction can be increased. This can increase strength against vibration and prevent fluttering.
Additionally, since the rigidity imparting member is only provided at a portion of the high-pressure side plate, the rigidity of the high-pressure side plate is not excessively increased. Hence, although the rigidity of the high-pressure side plate is increased, flexibility remains to such a degree to cope with a change in the shape of the seal body. Therefore, the high-pressure side plate can be made to reliably contact and follow the side surface of the seal body.
[0012]
Additionally, in the above-described shaft sealing device, the rigidity imparting member is a supporting plate portion that extends from the stator toward the radial inner side so as to be stacked on the surface of the high-pressure side plate that faces the high-pressure region and that has an extending length set to be shorter than that of the high-pressure side plate.

[0013]
According to this configuration, the rigidity of the high-pressure side plate can be reliably increased by a supporting plate portion.
Additionally, since the supporting plate portion is not provided at the portion of the high-pressure side plate on the radial inner side, the flexibility of the portion of the high-pressure side plate on the radial inner side can be secured, and the portion can be reliably made to follow the seal body.
[0014]
Moreover, in the above-described shaft sealing device, it is preferable that the supporting plate portion have a plurality of plate pieces stacked in the direction of the axis, and the plurality of plate pieces have a shorter extending length as they are arranged further toward the high-pressure region.
[0015]
Accordingly, the rigidity can be increased gradually from the radial inner side toward the radial outer side, and the followability to the seal body can be secured gradually from the radial outer side toward the radial inner side.
[0016]
Additionally, in the above-described shaft sealing device, the rigidity imparting member may be a plurality of ribs that are provided at intervals in the circumferential direction on the surface of the high-pressure side plate that faces the high-pressure region.
[0017]
According to this configuration, the high-pressure side plate is reinforced by the ribs, and the rigidity thereof can be reliably increased.
Additionally, since flexibility can be secured in a place where the ribs are not

provided, the high-pressure side plate can be reliably made to follow the seal body.
[0018]
Moreover, in the above-described shaft sealing device, it is preferable that the thin plate sealing pieces extend toward a forward side in a rotational direction of the rotor as they go toward the radial inner side, and the ribs extend toward the forward side in the rotational direction as they go toward the radial inner side.
[0019]
Accordingly, since the ribs can be provided over the whole region of the high-pressure side plate, the rigidity of the high-pressure side plate can be increased over the whole region.
[0020]
Additionally, in the above-described shaft sealing device, the rigidity imparting member may be an elastic member that presses a portion of the high-pressure side plate from the high-pressure region side toward the low-pressure region side.
[0021]
According to this configuration, the elastic member can press the high-pressure side plate toward the seal body to thereby impart rigidity to the high-pressure side plate, and the vibration of the high-pressure side plate when the rotor has rotated can be suppressed.
[0022]
Moreover, the shaft sealing device of the present invention may include a plurality of fins, which extend in the radial direction, are provided at intervals in the circumferential direction, and suppress a fluid that flows in the circumferential direction, on the high-pressure region side of the rigidity imparting member.

According to this configuration, by virtue of the fins, the swirl flow in the high-pressure region can be reduced, and an uneven flow can be suppressed, so that the fluttering of the high-pressure side plate can be reliably prevented.
[0024]
According to a second aspect of the present invention, a rotating machine includes any one of the above-described shaft sealing devices.
[0025]
According to this configuration, any one of the above-described shaft sealing devices is included. Therefore, it is possible to provide a rotating machine that can make the high-pressure side plate follow the seal body, can increase the rigidity of the high-pressure side plate, and can prevent the fluttering.
Advantageous Effects of Invention
[0026]
According to the shaft sealing device of the present invention and the rotating machine including the same, the followability of the high-pressure side plate to the seal body can be secured while the rigidity of the high-pressure side plate can be increased by the rigidity imparting member. Therefore, it is possible to prevent fluttering.
Brief Description of Drawings
[0027]
FIG. 1 is a schematic overall configuration view of a gas turbine (rotating machine) according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line S1-S1 in FIG. 1.
FIG. 3 is a cross-sectional view of a shaft sealing device according to a first

embodiment of the present invention taken along line S2-S2 in FIG. 2.
FIG. 4 is the schematic view when the shaft sealing device according to the first embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 5 is the schematic view when a high-pressure side plate of the shaft sealing device according to the first embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 6 is a schematic view when the shaft sealing device according to the first embodiment of the present invention is viewed from a radial inner side to a radial outer side.
FIG. 7 is a cross-sectional view of a shaft sealing device according to a second embodiment of the present invention taken along line S2-S2 in FIG. 2.
FIG. 8 is the schematic view when a high-pressure side plate of the shaft sealing device according to the second embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 9 is a schematic view when the shaft sealing device according to the second embodiment of the present invention is viewed from a radial inner side to a radial outer side.
FIG. 10 is a cross-sectional view of a shaft sealing device according to a third embodiment of the present invention taken along line S2-S2 in FIG. 2.
FIG. 11 is the schematic view when a high-pressure side plate of the shaft sealing device according to the third embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 12 is a schematic view when the shaft sealing device according to the third embodiment of the present invention is viewed from a radial inner side to a radial outer

side.
FIG. 13 is the schematic view when a high-pressure side plate of a shaft sealing device according to a modified example of the third embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 14 is a schematic view when a shaft sealing device according to a fourth embodiment of the present invention is viewed from a radial inner side to a radial outer side.
FIG. 15 is a cross-sectional view of the shaft sealing device according to the fourth embodiment of the present invention taken along line S2-S2 in FIG. 2.
FIG. 16 is the schematic view when a high-pressure side plate of the shaft sealing device according to the fourth embodiment of the present invention is viewed from one axial side to the other axial side in the axial direction.
FIG. 17 is a schematic view when the shaft sealing device according to the fourth embodiment of the present invention is viewed from a radial inner side to a radial outer side.
Description of Embodiments
[0028]
(First Embodiment)
A rotating machine according to a first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic overall configuration view of a gas turbine (rotating machine) 1 according to the embodiment of the present invention.
The gas turbine 1, as shown in FIG. 1, includes a compressor (rotating machine) 2, a combustor 3, and a turbine (rotating machine) 4.

The compressor 2 takes a large amount of air thereinto and compresses the air. The combustor 3 mixes the compressed air compressed by the compressor 2 with fuel and combusts the resulting mixture. The turbine 4 converts the heat energy of the combustion gas introduced from the combustor 3 into rotational energy.
[0029]
The compressor 2 and the turbine 4 respectively include rotors 2A and 4A that are coupled together so as to integrally rotate, and stators 2B and 4B that surround the outer peripheries of the rotors 2A and 4A. In addition, in the following description, unless particularly mentioned, the direction of an axis O of the rotors 2A and 4A is simply referred to as a "direction of the axis O", the circumferential direction of the rotors 2A and 4A is simply referred to as a "circumferential direction", and the radial direction of the rotors 2A and 4A is simply referred to as a "radial direction".
[0030]
The rotor 2A, 4A has a rotating shaft 6c, 6 and a plurality of annular compressor blade group 7c and turbine blade group 7 that are fixed at intervals in the direction of the axis O. Each annular compressor blade group 7c and turbine blade group 7 is configured to have a plurality of compressor blades and turbine blades that are fixed at intervals from each other in the circumferential direction, at the outer periphery of the rotating shaft 6c, 6.
[0031]
Each stator 2B, 4B includes a casing 2b, 4b, and a plurality of annular compressor vane group 5c and turbine vane group 5 that are fixed at intervals in the direction of the axis O within the casing 2b, 4b.
The annular compressor vane group 5c and turbine vane group 5 is configured to have a plurality of compressor vanes and turbine vanes that are fixed at intervals from

each other in the circumferential direction on the inner surface of each casing 2b, 4b. A hub shroud is formed at the tip of each compressor vane and turbine vane. The hub shrouds (stators) are coupled together in the circumferential direction, become annular as a whole, and surround the outer periphery of the rotating shaft 6c, 6.
The annular compressor vane group 5c and turbine vane group 5 are arranged in the direction of the axis O alternately with the plurality of annular compressor blade group 7c and turbine blade group 7.
[0032]
In the compressor 2 and the turbine 4, in order to prevent a working fluid (compressed air or combustion gas) g from leaking out in the direction of the axis O from a high-pressure side to a low-pressure side, as shown in FIG. 1, a shaft sealing device 10c, 10 is provided at the hub shrouds of each annular compressor vane and turbine vane group 5c, 5. Additionally, in order to prevent the working fluid g from leaking from the high-pressure side to the low-pressure side, shaft sealing devices 10c, 10 are provided also at bearings (stators) 2c, 4c where the casings 2b, 4b support the rotating shaft 6c, 6.
[0033]
An embodiment of a shaft sealing device 10 of the turbine 4 will be described below. In addition, the shaft sealing device 10 of the turbine 4 will be described below, and since the shaft sealing device 10c of the compressor 2 also has basically the same configuration, a description thereof is omitted here.
[0034]
FIG. 2 is a cross-sectional view taken along line S1-S1 in FIG. 1, and FIG. 3 is a cross-sectional view taken along line S2-S2 in FIG. 2.
As shown in FIG. 2, the shaft sealing device 10 of the turbine 4 is configured by arranging a plurality of (eight in the present embodiment) sealing segments 11, which

extend in a circular-arc shape, in the circumferential direction within a housing 9 that is an annular space supported by the hub shrouds of the annular turbine vane group 5 and the inner peripheral surface of the bearing 4c, respectively. The sealing segments 11 are segmented so as to go to a forward side in a rotational direction from a radial outer side toward a radial inner side.
[0035]
The housing 9 extends over the whole circumference in the circumferential direction along the outer periphery of the rotating shaft 6, and has an annular accommodation space 9a formed therein (see FIG. 3). As shown in FIG. 3, the opening side of the accommodation space 9a of the housing 9, that is, the portion of the accommodation space on the radial inner side serves as an inside space 9b of which the width dimension (dimension in the direction of the axis O) is made small. Additionally, a space spaced apart radially outward from the opening of the accommodation space 9a, that is, a space located further to the radial outer side than the inside space 9b serves as an outside space 9c of which the width dimension is made large. The inside space 9b and the outside space 9c are brought into a mutually communicating state. Also, an opening portion 9d of the inside space 9b faces the rotating shaft 6 on the radial inner side.
[0036]
The sealing segment 11, as shown in FIG. 3, includes a seal body 12 (refer to FIG. 4), retaining rings 13 and 14, a high-pressure side plate 16, a low-pressure side plate 17, and a rigidity imparting member 30.
The seal body 12 has multiple thin plate sealing pieces 20. The retaining rings 13 and 14 have a U-shaped cross-section and retain the multiple thin plate sealing pieces 20. The high-pressure side plate 16 and the low-pressure side plate 17 are provided so

that the seal body 12 is sandwiched therebetween from the direction of the axis O.
[0037]
FIG. 4 is a schematic view when the sealing segment 11 is viewed from one side to the other side in the direction of the axis O.
In the seal body 12, as shown in FIG. 4, the multiple thin plate sealing pieces 20 are stacked (refer to FIG. 2), and the ends of a number of the thin plate sealing pieces 20 on the radial outer side, that is, the rear ends 20a of the thin plate sealing pieces 20 are coupled together. As shown in FIG. 2, the multiple thin plate sealing pieces 20 are disposed so as to go to the forward side in the rotational direction from the radial outer side toward the radial inner side.
Additionally, each thin plate sealing piece 20, as shown in FIG. 3, is a member that is formed of mainly a thin steel sheet, is formed in a T-shape as viewed from the circumferential direction of the rotating shaft 6, and is arranged such that the width direction is turned toward the direction of the axis O of the rotating shaft 6. In other words, the thin plate sealing piece 20 is arranged such that the thickness direction thereof is turned toward the circumferential direction of the rotating shaft 6.
[0038]
The thin plate sealing piece 20 has a head 21, a body 23 that is formed such that the width dimension and thickness dimension thereof are smaller than those of the head 21, and a neck 22 that is located between the head 21 and the body 23 and is formed such that the width dimension thereof is smaller than the width dimension of the head and the body. The thin plate sealing piece 20 is formed so as to be continuous in order of the head 21, the neck 22, and the body 23 from the radial outer side of the rotating shaft 6 toward the radial inner side thereof.

The multiple thin plate sealing pieces 20 are mutually coupled by their respective heads 21 being welded to each other. Additionally, the bodies 23 of the multiple thin plate sealing pieces 20 are made elastically deformable, and the end portions of the respective bodies 23 on the radial inner side, that is, the tips 20b of the thin plate sealing pieces 20 are free ends. The tips 20b of the respective thin plate sealing pieces 20 come into contact with the rotating shaft 6 at predetermined precompression at the time of the stop of the rotating shaft 6.
[0040]
As shown in FIG. 4, the multiple thin plate sealing pieces 20 are arranged with small clearances s between each other in the circumferential direction. In the thin plate sealing pieces 20, the thickness dimension of the head 21 is set to be larger than the thickness dimension of the neck 22 and the body 23, whereby a small clearance s is formed between the bodies 23 of two thin plate sealing pieces 20 that are adjacent to each other in the thickness direction.
[0041]
In the seal body 12 including such multiple thin plate sealing pieces 20, high-pressure side end portions (other end portions) 12c is faced to a fluid high-pressure region (the other side of the axial direction), wherein the high-pressure side end portions 12c are formed in the shape of a layered structure which is configured by multiple side end portions 20c of the bodies 23 of the respective thin plate sealing pieces 20. Moreover, low-pressure side end portions 12d is faced to a fluid low-pressure region (the one side of the axial direction), wherein the low-pressure side end portions 12d are formed in the shape of a layered structure which is configured by multiple side end portions 20d of the body 23.

The retaining rings 13 and 14 are members that extend in the circumferential direction of the rotating shaft 6, and both are formed in a U-shape in a cross-section including the axis O. The portions of the heads 21 of the thin plate sealing pieces 20 on the high-pressure side are fitted into a groove portion of the retaining ring 13, and the portions of the heads 21 of the thin plate sealing pieces 20 on the low-pressure side are fitted into a groove portion of the retaining ring 14. Accordingly, the heads 21 of the multiple thin plate sealing pieces 20 are retained by the retaining rings 13 and 14.
[0043]
As shown in FIG. 2, the thickness direction of the high-pressure side plate 16 is turned to the direction of the axis O and the shape thereof as viewed from the direction of axis O of the rotating shaft 6 is a circular-arc strip shape. Additionally, the high-pressure side plate 16 is segmented in the circumferential direction into a plurality of portions (eight in the present embodiment) so as to go to the forward side in the rotational direction from a radial outer side toward the radial inner side. Additionally, each of the segmented high-pressure side plate pieces 16p is disposed with a clearance from an adjacent high-pressure side plate piece 16p.
Additionally, as shown in FIG. 3, the high-pressure side plate 16 has a base portion 16a that is an end portion on the radial outer side, and a sealing plate portion 16b that extends from the base portion 16a toward the radial inner side.
[0044]
The base portion 16a of the high-pressure side plate 16 is retained by the retaining ring 13 so as not to be dropped in the radial direction in a state where the base portion has entered a recess on the high-pressure side between the head 21 and the body 23 of the thin plate sealing piece 20. Additionally, the base portion 16a has a thickness (the dimension in the direction of the axis O) that is larger than the thickness (the

dimension in the direction of the axis O) of the sealing plate portion 16b, and protrudes in the direction of the axis O with the sealing plate portion 16b as a reference.
[0045]
The sealing plate portion 16b of the high-pressure side plate 16 extends toward the radial inner side such that the end portion thereof on the radial outer side is aligned with the end portion of the base portion 16a on the radial outer side and so as to be stacked on the surface of the base portion 16a that faces the fluid high-pressure region. Additionally, the end portion of the sealing plate portion 16b, that is, the tip of the sealing plate portion 16b extends to the opening portion 9d of the accommodation space 9a on the radial inner side. Accordingly, the tip 20b of the thin plate sealing piece 20 that extends from the accommodation space 9a toward the radial inner side extends further toward the radial inner side than the tip of the high-pressure side plate 16.
[0046]
The rigidity imparting member 30 is arranged so as to be stacked on the surface of the high-pressure side plate 16 that faces the fluid high-pressure region, and imparts rigidity in the direction of the axis O to a portion of the high-pressure side plates 16. In the present embodiment, the rigidity imparting member 30 has a supporting plate portion 30a. The supporting plate portion 30a has a first plate piece 16c stacked on the surface of the sealing plate portion 16b that faces the fluid high-pressure region, and a second plate piece 16d stacked on the surface of the first plate piece 16c that faces the fluid high-pressure region.
[0047]
As shown in FIGS. 3, 5, and 6, the end portion of the first plate piece 16c on the radial outer side is aligned with the end portion of the sealing plate portion 16b on the radial outer side. The first plate piece 16c extends toward the radial inner side so as to

be stacked on the surface of the sealing plate portion 16b that faces the fluid high-pressure region. Additionally, the radial dimension (extending length) of the first plate piece 16c is shorter than the radial dimension (extending length) of the sealing plate portion 16b. In other words, the end portion of the first plate piece 16c, that is, the tip of the first plate piece 16c, extends further toward the radial outer side than the tip of the sealing plate portion 16b.
[0048]
The second plate piece 16d extends toward the radial inner side such that the end portion thereof on the radial outer side is aligned with the end portion of the first plate piece 16c on the radial outer side and so as to be stacked on the surface of the first plate piece 16c that faces the fluid high-pressure region. Additionally, the radial dimension (extending length) of the second plate piece 16d is shorter than the radial dimension (extending length) of the first plate piece 16c. In other words, the end portion of the second plate piece 16d, that is, the tip of the second plate piece 16d, extends further toward the radial outer side than the tip of the first plate piece 16c.
In this way, the respective radial dimensions (extending lengths) of the sealing plate portion 16b, the first plate piece 16c, and the second plate piece 16d are set so as to become shorter in this order. In other words, the radial length of the supporting plate portion 30a is made shorter than that of the high-pressure side plate 16.
Additionally, the radial dimension (extending length) of the first plate piece 16c is set to about two-thirds of the radial dimension (extending length) of the sealing plate portion 16b.
Additionally, the base portion 16a, the sealing plate portion 16b, the first plate piece 16c, and the second plate piece 16d are fixed by spot welding or the like on the radial outer side. On the other hand, the base portion, the sealing plate portion, the first