JP2002161711A - Shaft seal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft seal structure to enable sealing firmly even in a part having a high pressure difference and free from defects such as damage. SOLUTION: A shaft seal member body 22 is provided around the shaft of the rotary shaft 1 in the peripheral direction. An expansion chamber formed in the rotary shaft 1, labyrinth fins, and floating rings having fine gap to the outer periphery of the rotary shaft 1 arranged in the peripheral direction are provided alternately in the shaft direction on the inner peripheral surface of the shaft seal member body 22. An accommodating groove 37 is formed on the inner peripheral surface of the shaft seal member body. Support springs 33 which protrude to the outer peripheral side, disposed in the accommodating groove 37 and absorb the force pressing to the side faces of the accommodating groove 37 by elastic deformation are provided to the floating rings along 26 the peripheral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal structure provided at a location having a pressure difference around a rotating shaft of a turbine or the like.

[0002]

2. Description of the Related Art In general, a gas turbine or a steam turbine is provided with a shaft seal structure around a rotation shaft to seal between pressure chambers in each housing or between the inside and the outside of the housing. FIG. 8 shows a steam turbine. The steam turbine has a low pressure dummy ring 3 and a high pressure dummy ring 4 provided in a housing 2 around an axis of a rotating shaft 1 thereof, and a rotating shaft 1. The shaft seal structure 5 described above is provided between the rotary shaft 1 and the end of the housing 2.

[0003] As this shaft seal structure, for example, there is the following. As shown in FIG. 9, a plurality of fins 11 are provided on the fixed side of the housing 2, the low pressure dummy ring 3, and the high pressure dummy ring 4, and a labyrinth seal structure that suppresses fluid leakage by forming a complicated flow path around the axis. .

As shown in FIG. 10, a floating ring 13 having an inner diameter larger than the outer diameter of the rotating shaft 1 is housed in a housing groove 12 formed on the fixed side in a non-contact manner with the rotating shaft 1, and a pressure difference is generated. Floating ring 13 with groove 1
2 is a floating ring seal structure in which the flow path is restricted to a narrow portion between the rotary shaft 1 and the leak by using the viscous resistance of the fluid to suppress leakage.

[0005] As shown in FIG.
There is known a brush seal structure in which a large number of wires 14 are extended toward an end to suppress an axial leak. In addition,
A brush seal structure using a thin leaf in place of the wire 14 is also known.

[0006]

However, particularly in a high-pressure turbine such as a steam turbine, the following problems occur even with each of the seal structures described above.

(1) Labyrinth seal structure In this labyrinth seal structure, there are many leaks between the fins 11 and the rotating shaft 1, and the sealing becomes insufficient at a high differential pressure portion.

(2) Floating ring seal structure When a high differential pressure is applied, the floating ring 13
Of the storage groove 12 is too large, the floating behavior of the floating ring 13 is hindered, and the floating ring 13 comes into contact with the rotating shaft 1 to cause damage to the sealing surface.
Pressing against the side of 2 will cause a great deal of wear. Also, due to the pressure on the outer peripheral side of the floating ring 13,
The floating ring 13 is deformed by pressure, and again comes into contact with the rotating shaft 1, causing problems such as damage to the sealing surface.

(3) Brush seal structure The wire 14 or the leaf is deformed due to the high pressure difference, so that sufficient sealing cannot be performed. Further, since the structure is such that the wire 14 or the leaf is in contact with the rotating shaft 1, the wear is severe and the life is short. In addition, the structure is such that a large number of wires 14 or leaves are fixed to the fixed side and extended toward the rotating shaft 1, so that it is extremely expensive.

Further, a fin 11 having a labyrinth seal structure is provided.
A seal structure has been developed in which a flexible brush is installed in a part of the seal to improve the sealing performance.However, even in the case of a high differential pressure, the brush may be deformed and a good seal may not be obtained. Therefore, further improvement in sealing performance has been required.

The present invention has been made in view of the above circumstances, and has no troubles such as damage even in a high differential pressure portion.
It is an object of the present invention to provide a shaft seal structure capable of reliably performing sealing.

[0012]

In order to achieve the above object, a shaft seal structure according to claim 1 is installed in a location having a pressure difference in an axial direction of a rotating shaft installed and rotated in a housing. A shaft sealing structure for restricting leakage of fluid from a high pressure side to a low pressure side around a shaft, wherein the shaft sealing member body is fixed to the housing and disposed circumferentially around the axis of the rotating shaft. And a floating ring installed on the inner peripheral side of the shaft sealing member body so as to extend in the circumferential direction with a small gap from the outer peripheral surface of the rotary shaft, and the shaft sealing member body A storage groove is formed along the circumferential direction on the inner peripheral surface of the floating ring, and the floating ring is disposed in the storage groove so as to protrude outward and elastically deform the pressing force against the side surface of the storage groove. The support spring that absorbs It is characterized in that is provided along the direction.

[0013] As described above, since the floating ring is provided with the support spring disposed in the storage groove formed in the inner peripheral surface of the shaft sealing member body so as to protrude in the outer peripheral direction, the floating ring has When a large pressing force from the high pressure side to the low pressure side is applied, the support spring in the storage groove is elastically deformed, so that the pressing force can be reliably absorbed, thereby generating a high differential pressure in particular. When applied to a steam turbine, it is possible to reliably prevent the floating behavior of the floating ring from rotating with respect to the rotating shaft due to the pressing force, and to eliminate damage due to contact between the inner peripheral surface of the floating ring and the outer peripheral surface of the rotating shaft. Can maintain a good sealing state, can reduce wear, and extend the life. That. Further, since the floating ring portion does not contact the main body, the floating ring portion has good followability to the rotor, and its operation is stable without causing abrasion.

According to a second aspect of the present invention, a shaft seal structure is provided.
In the shaft seal structure described above, the support spring has a plurality of spring pieces that are curved in the same circumferential direction toward the outer peripheral side and extend with a small gap therebetween.

That is, the pressing force applied to the floating ring due to the differential pressure is ensured by the support spring composed of a plurality of spring pieces which are curved in the same circumferential direction toward the outer peripheral side and extend with a small gap therebetween. Can be absorbed.

According to a third aspect of the present invention, there is provided a shaft seal structure.
Alternatively, in the shaft seal structure according to claim 2, a plurality of the support rings are overlapped and provided slightly shifted in a circumferential direction.

That is, since the support springs are superposed and slightly shifted in the circumferential direction,
It is possible to make the absorption of the elastic deformation by the support spring act in a well-balanced manner. In particular, in the case of the shaft seal structure according to claim 2, when the spring is constituted by a plurality of spring pieces, the spring pieces are mutually connected. The minute gap between them is closed, and a more reliable sealing effect can be obtained.

According to the fourth aspect of the present invention, there is provided a shaft seal structure.
4. The shaft seal structure according to any one of claims 1 to 3, wherein one end of the floating ring is fixed to the inner peripheral surface of the floating ring, and the inner peripheral surface of the floating ring extends along the rotation direction side of the rotating shaft. On the other hand, a plurality of foil segments made of a thin plate arranged with a small gap are provided.

That is, a plurality of foil segments made of a thin plate are provided on the inner peripheral surface of the floating ring along the rotation direction side of the rotating shaft with a small gap from the inner peripheral surface of the floating ring. Therefore, for example, even if the floating ring behaves due to mechanical vibration and the like, and its inner peripheral surface approaches the rotation axis,
The foil segment is flexibly elastically deformed to the outer peripheral side along the rotation axis, and the large pressure generated in the vicinity thereof can push the floating ring back to a predetermined position, whereby the floating ring comes into contact with the rotation axis. Can be reliably prevented.

The shaft seal structure according to the fifth aspect is the fourth aspect.
The above-mentioned shaft seal structure is characterized in that a portion near the tip end of the foil segment is disposed so as to overlap with the foil segment on the rotation direction side of the rotating shaft.

As described above, since the vicinity of the tip of the foil segment is superimposed on the foil segment adjacent on the rotation direction side of the rotating shaft, the foil segment can be precisely spaced from the inner peripheral surface of the floating ring. Can be arranged in a state of being opened along.

According to the sixth aspect of the present invention, there is provided a shaft seal structure.
The shaft seal structure according to any one of claims 1 to 5, wherein a seal fin that protrudes toward an outer peripheral side is provided along a circumferential direction on the high-pressure side in an outer periphery of the floating ring, and an inner peripheral surface of the shaft sealing member main body. Is characterized in that a storage groove in which the seal fin is provided is formed.

That is, a seal fin projecting toward the outer periphery is provided on the high pressure side on the outer periphery of the floating ring, and the seal fin is disposed in a storage groove formed on the inner periphery of the shaft sealing member main body. Since the labyrinth seal is composed of these seal fins and the storage groove,
The sealing can be reliably performed on the high pressure side on the outer peripheral side of the floating ring, thereby preventing pressure deformation of the floating ring due to high pressure applied to the outer peripheral side of the floating ring. Damage due to contact with the rotating shaft can be reliably prevented.

According to the seventh aspect of the present invention, a shaft seal structure is provided.
6. The shaft seal structure according to any one of items 5 to 5, further comprising a ring disposed along the support ring on the high pressure side on the outer periphery of the floating ring.

That is, since the ring is provided along the support ring on the high pressure side on the outer periphery of the floating ring, the sealing effect can be further improved by this ring. In particular, the support ring can be formed by a plurality of spring pieces. With this configuration, a minute gap between the spring pieces is closed, and a more reliable sealing effect can be obtained. Further, in particular, since it is not necessary to form a space for accommodating the ring in the shaft sealing member, processing can be facilitated and cost reduction can be achieved as compared with a case where a separate storage space is formed. Can be achieved.

The shaft seal structure according to the eighth aspect is the first aspect.
In the shaft seal structure according to any one of (1) to (7), a labyrinth fin protruding toward a rotation shaft side is provided on an inner peripheral surface of the shaft sealing member main body along a circumferential direction. An expansion chamber is formed, and the labyrinth fin and the expansion chamber constitute a labyrinth seal.

As described above, in addition to the sealing by the floating ring, the labyrinth fin provided on the inner peripheral surface of the shaft sealing member main body and the labyrinth seal formed by the expansion chamber formed on the rotary shaft can be reliably sealed. An even better seal structure can be obtained.

According to the ninth aspect of the present invention, there is provided a shaft seal structure according to the first aspect.
9. The shaft seal structure according to any one of claims 8 to 8, wherein a plurality of labyrinth seals including the labyrinth fins and the expansion chamber and a plurality of the floating rings are provided on the inner peripheral surface of the shaft sealing member main body along the axial direction. It is characterized by being provided alternately.

That is, since a plurality of seals by the floating ring and a plurality of labyrinth seals composed of the labyrinth fins and the expansion chamber are provided alternately along the axial direction, a more reliable seal structure can be obtained.

According to a tenth aspect of the present invention, there is provided a shaft seal structure which is installed in a location having a pressure difference in an axial direction of a rotating shaft which is installed and rotated in a housing and leaks fluid from a high pressure side to a low pressure side around the axis. A shaft seal structure that limits
A shaft sealing member main body fixed to the housing and disposed circumferentially around the axis of the rotation shaft; and a minute inner surface of the shaft sealing member main body with respect to an outer peripheral surface of the rotation shaft. And a floating ring installed in the circumferential direction with a gap, wherein the floating ring has
A plurality of foil segments each formed of a thin plate having one end fixed to the inner peripheral surface of the floating ring and arranged with a small gap from the inner peripheral surface of the floating ring along the rotation direction side of the rotating shaft; Is provided.

That is, a plurality of foil segments made of a thin plate are provided on the inner peripheral surface of the floating ring along the rotation direction side of the rotating shaft with a small gap from the inner peripheral surface of the floating ring. Therefore, for example, even if the floating ring behaves due to mechanical vibration and the like, and its inner peripheral surface approaches the rotation axis,
The foil segment is flexibly elastically deformed to the outer peripheral side along the rotation axis, and the large pressure generated in the vicinity thereof can push the floating ring back to a predetermined position, whereby the floating ring comes into contact with the rotation axis. Damage due to the floating ring can be reliably prevented, and a favorable sealing state by the floating ring can be maintained.

According to the eleventh aspect of the present invention, the shaft seal structure is installed at a location having a pressure difference in the axial direction of the rotating shaft installed and rotated in the housing, and fluid leakage from the high pressure side to the low pressure side around the axis is provided. A shaft seal structure that limits
A shaft sealing member main body fixed to the housing and disposed circumferentially around the axis of the rotation shaft; and a minute inner surface of the shaft sealing member main body with respect to an outer peripheral surface of the rotation shaft. And a floating ring installed in the circumferential direction with a gap, wherein the floating ring has
A seal fin protruding toward the outer circumference is provided along the circumferential direction on the high pressure side of the outer circumference, and a storage groove in which the seal fin is provided is formed on the inner circumference of the shaft sealing member main body. It is characterized by having.

As described above, the seal fin projecting to the outer peripheral side is provided on the high pressure side on the outer peripheral side of the floating ring, and the seal fin is disposed in the storage groove formed on the inner peripheral surface of the shaft sealing member main body. Since the labyrinth seal is formed by the seal fins and the storage groove, the sealing can be reliably performed on the outer peripheral side of the floating ring on the high pressure side. This prevents pressure deformation of the floating ring due to the action of the floating ring, reliably prevents damage due to contact between the floating ring and the rotating shaft due to the pressure deformation, and maintains a good sealing state by the floating ring.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a shaft seal structure according to the present invention will be described below with reference to the drawings. In FIG.
Reference numeral 21 denotes a shaft sealing member. The left side in the figure is a high pressure side, and the right side is a low pressure side. This shaft sealing member 21 is
Shaft main body 2 fixed to housing 2 covering the outer periphery of
The shaft sealing member main body 22 is disposed around the rotating shaft 1 in the circumferential direction. A plurality of labyrinth fins 23 are embedded in the shaft sealing member body 22 along the axial direction of the rotating shaft 1 on the inner peripheral surface side. Reference numeral 24 denotes an expansion chamber for guiding steam passing through the labyrinth fins 23 into a large space to enhance the sealing effect, and is formed on the peripheral surface of the rotating shaft 1.

The rotary shaft 1 has a ridge 25 between the expansion chambers 24. The shaft sealing member main body 22 has a floating ring 26 at a position facing the ridge 25. Is provided.

As shown in FIGS. 2 and 3, the floating ring 26 includes a ring portion 31 disposed along the circumferential direction, and a plurality of ring members 31 provided on the inner circumferential surface of the ring portion 31 in the circumferential direction. Foil segment 32 and ring portion 31
Spring 33 provided in the circumferential direction on the outer peripheral surface of
And seal fins 34 arranged on the outer peripheral surface of the ring portion 31 in the circumferential direction on the high pressure side of the support spring 33.

The foil segment 32 is formed from a thin metal plate such as stainless steel, and has one end portion formed on the ring portion 3.
1 is bent to the inner circumferential surface side, and the bent portion 35 is disposed in a fixed groove 36 formed in the inner circumferential surface of the ring portion 31 along the width direction thereof, and is spot-welded. And the like.

As described above, the foil segment 32 fixed to the inner peripheral surface of the ring portion 31 has the other end directed in the direction of rotation of the rotary shaft 1 (the direction of the arrow a in FIG. 3) and the adjacent foil segment. It is arranged to overlap with 32,
A portion other than the bent portion 35 provided in the fixing groove 36 has a small gap with respect to the inner peripheral surface of the ring portion 31.

And this foil segment 32
A minute gap is provided with respect to the outer peripheral surface of the rotating shaft 1. In addition, an elastomer or the like can be used as the foil segment 32.

The support spring 33 and the seal fins 34 are disposed in storage grooves 37 formed on the inner peripheral surface of the shaft sealing member main body 22, respectively. The support spring 33 has a plurality of spring pieces 41 curved in the same circumferential direction, and is fitted in a fitting groove 42 formed in the outer circumferential surface of the ring portion 31 along the circumferential direction. Is fixed. A head portion 41a having a large width and a large thickness is formed at the distal end of each support spring 33.

The support springs 33 can be formed by electric discharge machining. For example, portions other than the portions to be the support springs 33 can be formed by etching. Note that the support spring 33 can be configured by laminating a plurality of thin plates. By forming the support spring 33 from a plurality of thin plates in this manner, the formation by etching can be facilitated. The support spring 33 may be formed integrally with the ring portion 31.

The seal fins 34 are fins formed in the circumferential direction. The seal fins 34 are also formed on the outer peripheral surface of the ring portion 31 by the fitting grooves 4 formed in the circumferential direction.
3 and are integrally attached. The seal fins 34 may also be formed integrally with the ring portion 31.

Next, the operation of the shaft seal structure having the above structure will be described. When the turbine operates and the rotary shaft 1 rotates at a high speed to perform compression, a high differential pressure is generated between both side portions of the shaft sealing member 21.

Here, in the shaft seal structure portion formed by the shaft sealing member 21, the labyrinth seal portion including the labyrinth fins 23 and the expansion chamber 24 seals, thereby reducing fluid leakage from the high pressure side to the low pressure side. You. Also,
The fluid leaked from the labyrinth seal portion is further reduced by the floating ring seal portion including the ridge 25 and the floating ring 26.

Here, a large pressing force from the high-pressure side to the low-pressure side is applied to the ring portion 31 constituting the floating ring 26, and this pressing force is provided on the outer peripheral side of the ring portion 31 to accommodate the storage groove 37. Spring 33 composed of a plurality of spring pieces 41 disposed therein
The whole is absorbed by elastic deformation.

Further, between the outer peripheral surface of the ring portion 31 of the floating ring 26 and the inner peripheral surface of the shaft sealing member main body 22, a seal fin 34 provided on the high pressure side of the outer peripheral surface of the ring portion 31 and the shaft sealing member Since the seal is sealed by the labyrinth seal portion formed by the storage groove 37 of the main body 22, high pressure is not applied to the outer peripheral surface side of the ring portion 31, whereby pressure deformation due to high pressure applied to the outer peripheral side of the ring portion 31 is achieved. Is reliably prevented.

When the inner peripheral surface of the ring portion 31 of the floating ring 26 comes close to the rotating shaft 1 due to mechanical vibration or the like, the foil segment 32 provided on the inner peripheral surface of the ring portion 31 rotates in this vicinity. The shaft 1 is elastically deformed elastically to the outer periphery along the outer peripheral surface, and damage due to contact with the rotating shaft 1 is prevented. When the ring portion 31 approaches the rotating shaft 1 in this manner, a large pressure is generated at this approaching portion, and the ring portion 31 is pushed back to a predetermined position by this pressure, and a gap between the outer peripheral surface of the rotating shaft 1 and Returned to proper dimensions.

As described above, according to the above-described shaft seal structure, the support spring 33 disposed in the housing groove 37 formed in the inner peripheral surface of the shaft sealing member main body 22 in the floating ring 26 extends in the outer peripheral direction. When the floating ring 26 is applied with a large pressing force from the high pressure side to the low pressure side, the storage groove 37 is provided.
By elastically deforming the support spring 33 inside, the pressing force can be reliably absorbed, and thus, when the support spring 33 is adapted to a steam turbine in which a high differential pressure is generated, the rotating shaft of the floating ring 26 due to the pressing force can be absorbed. 1 can be reliably prevented from hindering the floating behavior, damage caused by contact between the inner peripheral surface of the floating ring 26 and the outer peripheral surface of the rotating shaft 1 can be eliminated, and a good sealing state can be maintained. In addition, wear can be reduced, and the life can be extended.

Moreover, a plurality of foils made of a thin plate are provided on the inner peripheral surface of the floating ring 26 along the rotation direction of the rotary shaft 1 with a small clearance from the inner peripheral surface of the floating ring 26. Since the segments 32 are provided, even if the floating ring 26 behaves due to, for example, mechanical vibration and the inner peripheral surface thereof approaches the rotary shaft 1, the foil segment 32 is flexible toward the outer peripheral side along the rotary shaft 1. And the floating ring 26 can be pushed back to a predetermined position by a large pressure generated in the vicinity thereof.
Damage due to the floating ring 26 coming into contact with the rotating shaft 1 can be reliably prevented.

Further, since the vicinity of the tip end of the foil segment 32 is superimposed on the foil segment 32 adjacent to the rotating shaft 1 in the rotation direction, the foil segment 32 can be accurately positioned with respect to the inner peripheral surface of the floating ring 26. They can be arranged in a state where they are arranged along a small gap.

Further, on the high pressure side on the outer peripheral side of the floating ring 26, a seal fin 34 protruding toward the outer peripheral side is provided, and the seal fin 34 is formed in the storage groove 37 formed on the inner peripheral surface of the shaft sealing member main body 22. Is located within
Since a labyrinth seal is formed by the seal fins 34 and the storage grooves 37, the floating ring 2
6 can be reliably sealed on the high pressure side on the outer peripheral side, thereby preventing the pressure deformation of the floating ring 26 due to the high pressure acting on the outer peripheral side of the floating ring 26, and preventing the floating ring 26 from being deformed by the pressure deformation. Damage due to contact between the shaft 26 and the rotating shaft 1 can be reliably prevented.

Further, since a plurality of seals by the floating ring 26 and a plurality of labyrinth seals composed of the labyrinth fins 23 and the expansion chamber 24 are provided alternately along the axial direction, a more reliable sealing structure can be obtained. it can.

The support spring 33 includes:
Any shape may be used as long as the pressing force can be absorbed.
For example, a corrugated spring or a chevron spring formed in a waveform or a chevron along the circumferential direction can be used.

When the differential pressure is relatively small, a flexible brush can be used as the seal fin. Further, by providing a plurality of labyrinth structures including the seal fins 34 and the storage grooves 37 to form a micro labyrinth structure, the sealing effect on the outer peripheral side of the ring portion 31 can be further enhanced.

(Test Example) Here, the above-described shaft seal structure and the conventional shaft seal structure were combined with the low pressure dummy ring 3.
A comparative test was performed on the sealing performance between the rotating shaft 1 and the rotating shaft 1 (LP dummy ring portion) and between the end of the housing 2 and the rotating shaft 1 (ground portion).

FIG. 4 shows the result. It should be noted that reference symbol A in FIG.
Indicates the result of the shaft seal structure having the conventional labyrinth seal structure, reference numeral B indicates the result of the shaft seal structure having the conventional brush seal structure, and reference numeral C indicates the result of the shaft seal structure of the embodiment.

As is apparent from the drawing, the shaft seal structure C of this embodiment has a significantly larger leakage amount at each of the LP dummy ring portion and the ground portion than the conventional shaft seal structures A and B. Especially, as compared with the shaft seal structure A which is the conventional labyrinth seal structure,
The leak amount was reduced to 1/3.

In the above-described embodiment, the seal fins 34 are provided to improve the sealing performance. However, as shown in FIG. 5, the seal fins 34 are not provided, and only the seal by the support spring 33 is preferable. A good sealing property can be ensured. In this case, in order to further improve the sealing performance, as shown in FIG.
A ring 44 may be provided on the high pressure side of 3 to reduce the leak in the support spring 33.

Further, by providing the ring 44 along the support spring 33 on the outer peripheral side of the floating ring 26, a better sealing effect can be obtained without providing the seal fins 34.

That is, the seal fins 34 can be omitted, and as a result, the axial length of the floating ring 26 can be reduced, and the storage space for the seal fins 34 provided on the shaft sealing member main body 22 side is provided. The groove 37 can also be made unnecessary, so that the storage groove 37 is sufficient only for the support spring 33, so that the processing can be facilitated and the cost can be reduced. The ring 44 can be made of metal or the like, or may be a porous material.

FIG. 7 shows a structure in which a plurality of support springs 33 are overlapped in the axial direction and are slightly shifted from each other in the circumferential direction. They are fixed together.
The storage groove 37 is formed large so that the support springs 33 can be stored.

According to this structure, since the plurality of support springs 33 are overlapped and slightly shifted in the circumferential direction, a minute gap between the spring pieces 41 of the support spring 33 is overlapped. Is closed by the spring piece 41 of the support spring 33, whereby a more reliable sealing effect can be obtained.

[0063]

As described above, according to the shaft seal structure of the present invention, the following effects can be obtained. According to the shaft seal structure of the first aspect, since the floating ring is provided with the support spring disposed in the storage groove formed in the inner peripheral surface of the shaft sealing member main body so as to protrude in the outer peripheral direction. When a large pressing force from the high pressure side to the low pressure side is applied to the floating ring, the support spring in the storage groove is elastically deformed, so that the pressing force can be reliably absorbed. When applied to a steam turbine where a high differential pressure is generated, it is possible to reliably prevent the floating behavior of the floating ring from rotating with respect to the rotating shaft due to the pressing force, so that the contact between the inner peripheral surface of the floating ring and the outer peripheral surface of the rotating shaft can be prevented. Damage can be eliminated, a good seal can be maintained, wear can be reduced, and a longer life can be achieved. Rukoto can.

According to the shaft seal structure of the second aspect, the support spring is constituted by a plurality of spring pieces which are curved in the same circumferential direction toward the outer peripheral side and extend with a small gap therebetween. The pressing force applied to the floating ring by the pressure can be reliably absorbed.

According to the third aspect of the present invention, since the support springs are overlapped with each other and are slightly shifted in the circumferential direction, the elastic deformation of the support springs can be effectively absorbed. Further, particularly in the case of the shaft seal structure according to the second aspect, in the case of a structure formed of a plurality of spring pieces, a minute gap between the spring pieces is closed,
A more reliable sealing effect can be obtained.

According to the shaft seal structure of the fourth aspect, a small gap is provided on the inner peripheral surface of the floating ring along the rotation direction side of the rotating shaft with respect to the inner peripheral surface of the floating ring. Since a plurality of foil segments made of thin sheets are provided, for example, the floating ring behaves due to mechanical vibration and the like, and even if the inner peripheral surface is close to the rotation axis, the foil segment moves along the rotation axis toward the outer side. In addition to being elastically deformed, the floating ring can be pushed back to a predetermined position by a large pressure generated in the vicinity thereof, whereby damage due to the floating ring contacting the rotating shaft can be reliably prevented. .

According to the shaft seal structure of the fifth aspect, the vicinity of the tip end of the foil segment is superimposed on the foil segment adjacent on the rotation direction side of the rotary shaft, so that the foil segment can be accurately positioned inside the floating ring. It can be arranged in a state in which a minute gap is provided along the peripheral surface.

According to the shaft seal structure of the sixth aspect, seal fins projecting toward the outer peripheral side are provided on the high pressure side on the outer peripheral side of the floating ring, and the seal fins are formed on the inner peripheral surface of the shaft sealing member main body. Since the labyrinth seal is configured from the seal fins and the storage grooves arranged in the provided storage grooves, the sealing can be reliably performed on the high pressure side on the outer peripheral side of the floating ring,
Accordingly, pressure deformation of the floating ring due to high pressure acting on the outer peripheral side of the floating ring can be prevented, and damage due to contact between the floating ring and the rotating shaft due to the pressure deformation can be reliably prevented.

According to the shaft seal structure of the seventh aspect, since the ring is provided along the support ring on the high pressure side on the outer periphery of the floating ring, the sealing effect can be further improved by this ring.
In particular, when a support ring is formed by a plurality of spring pieces, a minute gap between the spring pieces is closed, and a more reliable sealing effect can be obtained. Also, in particular,
Since it is not necessary to form a space for accommodating the ring in the shaft sealing member, processing can be facilitated and cost can be reduced as compared with a case where a separate storage space is formed. it can.

According to the shaft seal structure of the present invention, the labyrinth fin provided on the inner peripheral surface of the shaft sealing member main body and the labyrinth seal formed by the expansion chamber formed on the rotary shaft together with the sealing by the floating ring. Sealing can be performed reliably, and a better sealing structure can be obtained.

According to the shaft seal structure of the ninth aspect, the plurality of seals by the floating ring and the plurality of labyrinth seals composed of the labyrinth fins and the expansion chamber are provided alternately along the axial direction, so that further reliability is ensured. A simple sealing structure can be obtained.

According to the shaft seal structure of the tenth aspect,
Since the inner peripheral surface of the floating ring is provided with a plurality of thin foil segments made of a thin plate disposed with a small gap with respect to the inner peripheral surface of the floating ring along the rotation direction side of the rotating shaft, For example, even if the floating ring behaves due to mechanical vibration and the inner peripheral surface is close to the rotation axis, the foil segment is elastically deformed to the outer circumference side along the rotation axis and a large pressure is generated in the vicinity. Allows the floating ring to be pushed back into place,
Damage due to the floating ring coming into contact with the rotating shaft is reliably prevented, and a favorable sealing state by the floating ring can be maintained.

According to the shaft seal structure of the eleventh aspect,
On the high pressure side on the outer peripheral side of the floating ring, a seal fin protruding to the outer peripheral side is provided, and this seal fin is disposed in a storage groove formed on the inner peripheral surface of the shaft sealing member main body. Since the labyrinth seal is configured from the storage groove, the sealing can be reliably performed on the high pressure side on the outer peripheral side of the floating ring, and thereby, the floating ring is formed by the high pressure acting on the outer peripheral side of the floating ring. Pressure deformation of the floating ring and the damage caused by the contact between the floating ring and the rotating shaft due to the pressure deformation can be reliably prevented, and a favorable sealing state by the floating ring can be maintained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a shaft sealing member for explaining a shaft sealing structure according to an embodiment of the present invention, as viewed in cross section.

FIG. 2 is a perspective view of a floating ring for explaining a shaft seal structure according to an embodiment of the present invention, as viewed in cross section.

FIG. 3 is a side view of a floating ring illustrating a shaft seal structure according to an embodiment of the present invention.

FIG. 4 is a graph showing a comparison test result of sealing performance between the shaft seal structure according to the embodiment of the present invention and a conventional shaft seal structure.

FIG. 5 is a perspective view of a floating ring for explaining a shaft seal structure according to another embodiment of the present invention, as viewed in section.

FIG. 6 is a cross-sectional perspective view of a floating ring for explaining a shaft seal structure according to another embodiment of the present invention.

FIG. 7 is a cross-sectional perspective view of a floating ring illustrating a shaft seal structure according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view of the turbine illustrating a schematic structure of the turbine to which the shaft seal structure is applied.

FIG. 9 is a cross-sectional view of a shaft seal structure for explaining a conventional shaft seal structure having a labyrinth seal structure.

FIG. 10 is a cross-sectional view of a shaft seal structure for explaining a conventional shaft seal structure having a floating ring seal structure.

FIG. 11 is a cross-sectional view of a shaft seal structure for explaining a conventional shaft seal structure including a brush seal structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation shaft 2 Housing 22 Shaft sealing member main body 23 Labyrinth fin 24 Expansion chamber 26 Floating ring 32 Foil segment 33 Support spring 34 Seal fin 37 Storage groove 41 Spring piece 44 Ring

Claims (11)

[Claims] 1. A shaft seal structure which is installed in a housing and has a pressure difference in an axial direction of a rotating shaft which is rotated and which is installed in a housing to limit fluid leakage from a high pressure side to a low pressure side around the shaft. A shaft sealing member body fixed to the housing and disposed circumferentially around the axis of the rotating shaft; and an inner peripheral side of the shaft sealing member body with respect to an outer peripheral surface of the rotating shaft. And a floating ring installed in the circumferential direction with a small gap therebetween.On the inner peripheral surface of the shaft sealing member main body, a storage groove is formed along the circumferential direction, and the floating ring is formed in the floating ring. A shaft is provided along the circumferential direction, the support spring protruding toward the outer peripheral side, being disposed in the storage groove, and elastically deforming and absorbing a pressing force against the side surface of the storage groove. Seal structure. 2. The shaft according to claim 1, wherein the support spring has a plurality of spring pieces that are curved in the same circumferential direction toward the outer peripheral side and extend with a small gap therebetween. Seal structure. 3. The shaft seal structure according to claim 1, wherein a plurality of the support rings are overlapped and provided slightly shifted in a circumferential direction. 4. An end of the floating ring is fixed to an inner peripheral surface of the floating ring, and a small gap is provided between the floating ring and the inner peripheral surface of the floating ring along a rotation direction side of the rotating shaft. The shaft seal structure according to any one of claims 1 to 3, wherein a plurality of foil segments made of a thin plate are provided. 5. The shaft seal structure according to claim 4, wherein the foil segment has a portion in the vicinity of the tip end thereof superposed on the foil segment on the rotation direction side of the rotating shaft. 6. The floating ring is provided with a seal fin protruding toward the outer periphery on the high pressure side of the outer periphery along the circumferential direction, and the seal fin is provided on an inner peripheral surface of the shaft sealing member main body. The shaft seal structure according to any one of claims 1 to 5, wherein a storage groove in which is disposed is formed. 7. The floating ring has a ring disposed along the support ring on the high pressure side of the outer periphery thereof.
The shaft seal structure according to any one of the above items. 8. A labyrinth fin protruding toward the rotation shaft is provided on an inner peripheral surface of the shaft sealing member main body along a circumferential direction, and an expansion chamber is formed on the rotation shaft, and the labyrinth is formed. The shaft seal structure according to any one of claims 1 to 7, wherein a labyrinth seal is constituted by the fin and the expansion chamber. 9. A plurality of labyrinth seals comprising said labyrinth fins and expansion chambers and a plurality of said floating rings are provided alternately along an axial direction on an inner peripheral surface of said shaft sealing member main body. Claim 1 to claim
9. The shaft seal structure according to any one of 8 above. 10. A shaft seal structure which is installed in a location having a pressure difference in an axial direction of a rotating shaft which is installed and rotated in a housing and restricts leakage of fluid from a high pressure side to a low pressure side around the axis. A shaft sealing member body fixed to the housing and disposed circumferentially around the axis of the rotating shaft; and an inner peripheral side of the shaft sealing member body with respect to an outer peripheral surface of the rotating shaft. A floating ring installed in the circumferential direction with a small gap therebetween. One end of the floating ring is fixed to the inner peripheral surface of the floating ring, and the floating ring is directed toward the rotation direction of the rotating shaft. A plurality of foil segments made of a thin plate disposed along the inner peripheral surface of the floating ring with a small gap along the shaft seal structure. 11. A shaft seal structure which is installed in a housing and has a pressure difference in an axial direction of a rotating shaft which is rotated and which limits fluid leakage from a high pressure side to a low pressure side around the shaft. A shaft sealing member body fixed to the housing and disposed circumferentially around the axis of the rotating shaft; and an inner peripheral side of the shaft sealing member body with respect to an outer peripheral surface of the rotating shaft. A floating ring installed in the circumferential direction with a small gap, and the floating ring has seal fins projecting toward the outer circumferential side along the circumferential direction on the high pressure side on the outer circumference. A shaft sealing structure, wherein a housing groove in which the seal fin is provided is formed on an inner peripheral surface of the shaft sealing member main body.