JP2006112491A - Shaft sealing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft sealing mechanism adopting a leaf seal capable of suppressing leak amount of working fluid even when relative eccentricity of a rotational shaft is excessively generated. <P>SOLUTION: A high-pressure side side plate 24 that is a component of the leaf seal 20 is constituted by stacking a second annular plate 32 and a first annular plate 31 in sequence toward each thin plate 21 of a thin plate group. The inner diameter of the first annular plate 31 is larger than that of the second annular plate 32, and the first annular plate 31 is brought into contact with one side that is the high-pressure side of the each thin plate 21. In an inner peripheral edge part of the second annular plate 32, a projection 38 comes into contact with the one side that is the high-pressure side of the each thin plate 21 is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shaft seal mechanism for a rotating shaft of a large fluid machine such as a gas turbine, a steam turbine, a compressor, a water turbine, a refrigerator, a pump, and the like, and in particular, is coaxial with the peripheral surface of the rotating shaft and the rotating shaft. The present invention relates to a shaft seal mechanism that suppresses leakage of working fluid from a high pressure side to a low pressure side in a gap with an inner peripheral surface of a stationary member that is stationary.

  In general, in a large fluid machine such as a gas turbine or a steam turbine, in addition to a main flow channel that essentially flows a working fluid such as compressed air, combustion gas, or steam (hereinafter sometimes simply referred to as “gas”), It is unavoidable that an annular gap is formed between the peripheral surface of the rotating shaft and the inner peripheral surface of a stationary member that is coaxial and stationary on the rotating shaft (for example, an annular member that holds the inner peripheral end of the stationary blade). Absent. If no measures are taken with respect to the gap, gas leaks inadvertently from the high-pressure side to the low-pressure side through the gap, resulting in a decrease in the efficiency of the fluid machine. Therefore, it is extremely important to minimize gas leakage through the gap, and in order to realize this, a shaft seal mechanism is applied to the gap.

  As the shaft seal mechanism, a non-contact type so-called labyrinth seal in which a plurality of fins protrude from the inner peripheral surface of a stationary member has been widely used. However, the labyrinth seal must be configured so that the tip of the fin does not come into contact with the peripheral surface of the rotating shaft even during axial vibration or thermal transient thermal deformation during the rotational transition period. As a result, there is a problem that gas leakage cannot be greatly suppressed.

  On the other hand, in recent years, as a shaft seal mechanism that can significantly reduce the amount of gas leakage, a so-called leaf seal having a structure in which flat thin plates having a certain width in the axial direction of the rotating shaft are arranged in the circumferential direction of the rotating shaft is provided. Yes (see, for example, Patent Document 1). Hereinafter, the detailed structure of the leaf seal will be described with reference to FIGS. Here, as a large-sized fluid machine to which a leaf seal is applied, a typical gas turbine will be described as an example.

  A gas turbine Gt shown in FIG. 10 includes a compressor 1 that takes in a large amount of air and compresses it, a combustor 2 that mixes fuel with the air compressed by the compressor 1 and burns, and a combustor 2. The generated high-temperature and high-pressure combustion gas is introduced into the turbine 3 that converts the thermal energy of the combustion gas into rotational energy, and the rotation that directly receives the rotational energy of the turbine 3 and transmits a part of it as power for the compressor 1. And a shaft 4.

  In the turbine 3, a plurality of rotor blades 10 provided in a plurality of stages in the axial direction on the rotating shaft 4 rotate together with the rotating shaft 4 by receiving the pressure of the sprayed combustion gas. Thus, power is generated by converting the thermal energy of the combustion gas into mechanical rotational energy called rotation of the rotating shaft 4. The rotational energy given to the rotating shaft 4 is taken out from the shaft end and used for power generation. In addition to the moving blade 10 on the rotating shaft 4 side, the turbine 3 is provided with a plurality of stationary blades 11 on the casing 9 side of the turbine 3. The moving blade 10 and the stationary blade 11 are connected to the rotating shaft. 4 are arranged alternately in the axial direction. The amount of combustion gas that leaks from the high pressure side to the low pressure side through the gap between the rotating shaft 4 and the stationary blade 11 (actually, an annular stationary member that holds the inner peripheral end of the stationary blade 11). A leaf seal 20 is provided as a shaft seal mechanism for reducing the above.

  The compressor 1 is coaxially connected to the turbine 3 at the rotating shaft 4, and uses the rotation of the rotating shaft 4 in the turbine 3 to suck and compress outside air into the combustor 2. Supply. In the compressor 1, similarly to the turbine 3, a plurality of moving blades 6 are provided on the rotating shaft 4, and a plurality of stationary blades 7 are provided on the casing 5 side of the compressor 1. The rotating shafts 4 are alternately arranged in the axial direction. The compressed air leaking from the high pressure side to the low pressure side through the gap between the rotating shaft 4 and the stationary blade 7 (here, actually, an annular stationary member that holds the inner peripheral end of the stationary blade 7). A leaf seal 20 is provided as a shaft seal mechanism for reducing the amount of leakage.

  Further, in the bearing portion 8 where the casing 5 of the compressor 1 supports the rotating shaft 4 and the bearing portion 12 where the casing 9 of the turbine 3 supports the rotating shaft 4, compressed air or A leaf seal 20 is provided as a shaft seal mechanism for preventing combustion gas from leaking.

  Subsequently, as shown in FIGS. 11 and 12, the leaf seal 20 is inserted into the stator 60 which is a stationary member corresponding to the stationary blades 7 and 11 and the bearing portions 8 and 12 (see FIG. 10). Is installed as a shaft seal mechanism for preventing gas leakage in the annular space in the gap between the peripheral surface of the stator 60 and the inner peripheral surface of the stator 60. The leaf seal 20 includes an annular thin plate group composed of a plurality of thin plates 21 stacked in a circumferential direction of the rotating shaft 4 with a minute gap therebetween (see FIG. 13A), and the thin plate group is formed into a thin plate 21. Each of the U-shaped retainers 22 and 23 sandwiched from both sides in the axial direction on the outer peripheral proximal end side, and one side and one retainer 22 located on the high pressure side (the gas pressure side) in the thin plate group The thin plate group is sandwiched between the divided annular high-pressure side plate 24 that is sandwiched and contacts one side of the thin plate group, the other side located on the low-pressure side (the low gas pressure side) of the thin plate group, and the other retainer 23. Of the divided annular low-pressure side plate 25 in contact with the other side, the connecting member 26 that connects the retainers 22 and 23 on the outer peripheral side of the thin plate 21, and rattling of the thin plates 21 held by the retainers 22 and 23. Spacer 27 to suppress Comprises a leaf spring 28 which sheet group that is grasped by the retainer 22, 23 provide a biasing force to be constant position with respect to the rotation axis 4, a.

  As shown in FIG. 12, each thin plate 21 that is a constituent element of the thin plate group is a thin, approximately T-shaped, with the width in the axial direction of the rotating shaft 4 at the outer peripheral base end being wider than the width at the inner peripheral end side. It is made of a steel plate, and on both sides thereof, notches 21a and 21b are provided at the stepped portions of the width. Here, each thin plate 21 is made of a rolled steel plate having a thickness of about 0.1 mm (for example, a metal steel plate made of stainless steel, Inconel, Hastelloy, etc.), and is first die-cut with a press or the like to obtain a constant thickness. It is molded into a predetermined shape (T-shape). Then, as shown in FIG. 14, the thickness of the thin plate 21 is removed by etching and removing only one surface on the inner peripheral end side (corresponding to the shaded portion 21d in FIG. 14) while leaving the outer peripheral base end portion as it is. A step is formed. However, it is also possible to simultaneously form such T-shaped contour formation and step formation by etching.

  Such thin plates 21 are stacked so as to have the same width in the axial direction of the rotary shaft 4 and, as shown in FIG. 13B, welded to the side surfaces of the outer peripheral base end and the wide portion on the outer peripheral base end side. Wd is applied and fixed, whereby a thin plate group is formed. In addition, each thin plate 21 is designed to have a predetermined rigidity in the circumferential direction of the rotating shaft 4 determined by the etched thickness t on the inner peripheral end side, and the rotating shaft 4 with respect to the rotating direction of the rotating shaft 4. Is held by retainers 22 and 23 so that the angle θ formed with the peripheral surface of the above becomes an acute angle. In the thin plate group, the depth c of the portion 21d removed by etching of each thin plate 21 is a minute gap between the thin plates 21.

  The high-pressure side plate 24 and the low-pressure side plate 25 are provided with protrusions 24a and 25a that protrude in the axial direction of the rotary shaft 4 at the outer peripheral edge portions, and these protrusions 24a and 25a are notches of the thin plate group. The parts 21a and 21b are respectively fitted. Further, the retainer 22 located on the high pressure side has a concave groove 22a on the surface facing the one side which is the high pressure side on the outer peripheral base end side in the thin plate group, and the retainer 23 located on the other low pressure side is in the thin plate group. A groove 23a is provided on the surface facing the other side which is the low pressure side on the outer peripheral base end side. In the thin plate group in which the protrusions 24a and 25a of the high-pressure side plate 24 and the low-pressure side plate 25 are fitted into the notches 21a and 21b, one side which is the high-pressure side on the outer peripheral base end side is the concave groove 22a of the retainer 22. And the other side, which is the low-pressure side of the outer peripheral base end side, is fitted into the recessed groove 23 a of the retainer 23.

  Here, the inner diameter of the high-pressure side plate 24 is slightly larger than the diameter of the rotating shaft, and the inner diameter of the low-pressure side plate 25 is larger than the inner diameter of the high-pressure side plate 24 by a predetermined amount. Accordingly, the inner peripheral end portion of each thin plate 21 in the thin plate group has a much larger exposed area in the axial direction on the other side, which is the low pressure side, than one side, which is the high pressure side.

  A connecting member 26 is inserted between the retainers 22 and 23 in which the outer peripheral proximal end side of the thin plate group is fitted, and the connecting members 26 are welded to the retainers 22 and 23 so that the retainers 22 and 23 are fixed. Is done. A spacer 27 is inserted between the outer peripheral proximal end of the thin plate group and the retainers 22 and 23 to fill the gap between them. Furthermore, concave grooves 22b and 23b are provided on the outer peripheral sides of the retainers 22 and 23 into which the spacers 27 are inserted, and a leaf spring 28 is fitted into one concave groove formed by the concave grooves 22b and 23b. As a result, the leaf spring 28 is fixed to the outer peripheral side of the retainers 22 and 23.

  As shown in FIG. 12, the leaf seal 20 having such a structure is an annular mounting groove formed integrally with a split annular mounting piece 62 and formed on the inner peripheral wall surface on the stator 60 side in the circumferential direction. 61, the retainers 22 and 23 are fitted along the circumferential direction. Here, the concave groove 61 is formed on the side surface facing the one side which is the high pressure side of the thin plate group so that the width on the outer peripheral side serving as the bottom is wider than the width on the inner peripheral side in the axial direction of the rotation shaft 4. The shape is provided with a step, and the surface 61 a on the outer peripheral side of the step is a sliding contact surface that is in sliding contact with the inner peripheral surface of the retainer 22 of the leaf seal 20. Further, the outer peripheral surface 61 b that is the bottom of the concave groove 61 is a sliding contact surface that comes into sliding contact with the leaf spring 28 provided on the outer peripheral side of the leaf seal 20. Further, the inner circumferential side width of the concave groove 61 is formed to be sufficiently wider than the width of the leaf seal 20 in the axial width of the rotating shaft 4.

  On the other hand, as shown in FIG. 12, in the axial direction of the rotating shaft 4, the mounting piece 62 is connected to the other side, which is the low pressure side of the thin plate group, so that the width on the outer peripheral side is narrower than the width on the inner peripheral side. A step is provided on the opposite side surface, and the outer surface 62a of the step is a sliding contact surface that is in sliding contact with the inner peripheral surface of the retainer 23 of the leaf seal 20. Further, in the mounting piece 62, the side surface 62 b facing the other side which is the low pressure side of the thin plate group is in contact with the low pressure side plate 25 in the wide inner peripheral side portion in the axial direction of the rotating shaft 4. It becomes the pressure receiving surface. Note that a labyrinth seal 62d is provided by projecting a part of the inner peripheral surface of the mounting piece 62. That is, the mounting piece 62 is installed on the downstream side of the leaf seal 20, and thereby, the labyrinth seal 62 d for further reducing the amount of gas leakage is installed downstream of the leaf seal 20.

  As described above, the leaf seal 20 is held together with the mounting piece 62 on the outer peripheral proximal end side with respect to the concave groove 61 of the stator 60. That is, the inner peripheral surfaces of the retainers 22 and 23 are in sliding contact with the sliding contact surface 61a of the recessed groove 61 and the sliding contact surface 62a of the mounting piece 62, and are fixed to the outer peripheral side of the retainers 22 and 23. Is in sliding contact with the sliding contact surface 61 b of the concave groove 61, so that the leaf seal 20 is maintained in a state of being fitted to the stator 60. Incidentally, since the leaf seal 20 is fitted into the concave groove 61 of the stator 60 using the mounting piece 62, the assembling work can be easily performed.

  At this time, the leaf seal 20 can move slightly in the axial direction of the rotary shaft 4 with respect to the inside of the concave groove 61. Therefore, when gas flows from the high pressure side region toward the low pressure side region, the gas pressure acts on each thin plate 21 of the leaf seal 20, so that the leaf seal 20 moves toward the low pressure side region, as will be described later. The low-pressure side plate 25 comes into contact with the pressure receiving surface 62 b of the mounting piece 62.

  Next, the operation of the leaf seal 20 configured as described above will be described. As shown in FIG. 15A, when a gas pressure from the high pressure side region toward the low pressure side region is applied to each thin plate 21, it is located on the inner peripheral end side and the highest pressure side region with respect to each thin plate 21. A gas pressure distribution 70a is formed in which the gas pressure is highest at the corner r1 and the gas pressure gradually decreases toward the diagonal corner r2. In FIG. 12, each thin plate 21 has a T-shape. However, in FIG. 11 and FIG. 15, only a rectangular portion that causes bending is illustrated for convenience.

  Further, as shown in a cross-sectional view along the circumferential direction of the rotating shaft 4 shown in FIG. 15B, the surface of each thin plate 21 facing the rotating shaft 4 is a lower surface 21q, and the back side is an upper surface 21p. And when the gas pressure which goes to a low pressure side area | region from a high voltage | pressure side area | region is added with respect to each thin plate 21, and the gas pressure distribution 70a as shown to Fig.15 (a) is formed, arbitrary along the cross section of each thin plate 21 The gas pressure is adjusted so that the gas pressure applied to the lower surface 21q is higher than the gas pressure applied to the upper surface 21p at the position.

  At this time, the gas g flowing from the high pressure side region toward the low pressure side region flows from between the high pressure side plate 24 and the peripheral surface of the rotating shaft 4. As shown in FIG. 15A, the gas g flows between the peripheral surface of the rotating shaft 4 and the inner peripheral end of the thin plate 21, and the gap between the upper surface 21 p and the lower surface 21 q of each adjacent thin plate 21. , And flows radially from the corner r1 to the corner r2. As the gas g flows in this manner, a low-pressure region expands toward the outer peripheral base end of each thin plate 21. Therefore, as shown in FIG. 15B, the gas pressure distributions 70b and 70c applied perpendicularly to the upper surface 21p and the lower surface 21q of each thin plate 21 become larger and closer to the inner peripheral end portion of each thin plate 21 and each thin plate 21. It becomes a triangular distribution shape that becomes smaller as it goes toward the outer periphery base end.

  The gas pressure distributions 70b and 70c on the upper surface 21p and the lower surface 21q have substantially the same shape, but the thin plates 21 are arranged so that the angle θ with respect to the peripheral surface of the rotating shaft 4 is an acute angle. The relative positions of the gas pressure distributions 70b and 70c on 21p and the lower surface 21q are shifted from the thin plate 21. Thereby, a difference arises in the gas pressure of the upper surface 21p and the lower surface 21q in the arbitrary points P which go to the inner peripheral end side from the outer peripheral base end side of the thin plate 21. Thus, in each thin plate 21, the gas pressure applied to the lower surface 21q is higher than the gas pressure applied to the upper surface 21p, so that the gas pressure of the gas flowing between the peripheral surface of the rotating shaft 4 and the inner peripheral end of the thin plate 21 is reduced. The inner peripheral edge of each thin plate 21 is generated in the direction of floating from the rotary shaft 4.

  In this way, by generating a pressure difference between the upper surface 21p and the lower surface 21q of each thin plate 21, the inner peripheral end of each thin plate 21 is deformed so as to float above the peripheral surface of the rotating shaft 4. That is, when the rotation of the rotating shaft 4 is stopped, the inner peripheral end of the thin plate 21 is in contact with the peripheral surface of the rotating shaft 4 with a predetermined preload (see FIG. 13A). Since the inner peripheral end of the thin plate 21 is lifted by the dynamic pressure effect generated by the rotation, the thin plate 21 and the peripheral surface of the rotary shaft 4 are in a non-contact state (see FIG. 13C). Thus, the leaf seal 20 divides the space around the rotary shaft 4 into a high pressure side region and a low pressure side region, and seals the outer periphery of the rotary shaft 4.

  At this time, since the gas g flows from the high pressure side region to the low pressure side region in this way, the fluid force is applied to the thin plate group from the high pressure side region to the low pressure side region as shown in FIG. F acts. When the thin plate group receives the fluid force F, the leaf seal 20 moves from the high pressure side region toward the low pressure side region. Then, as shown in FIG. 16B, the position of the leaf seal 20 is regulated by the low-pressure side plate 25 coming into contact with the pressure-receiving surface 62b of the mounting piece 62. At this time, the low-pressure side plate 25 is on the low-pressure side in the thin plate group. The distance between the other side and the pressure receiving surface 62 b of the mounting piece 62 is equal to the thickness of the low pressure side plate 25.

  This is because, since the inner diameter of the low-pressure side plate 25 is larger than the inner diameter of the thin plate group, there is an exposed area that does not contact the low-pressure side plate 25 on the inner peripheral end side of each thin plate 21 in the thin plate group. As a result, on the inner peripheral end side of each thin plate 21 in the thin plate group, a gap equal to the thickness of the low pressure side plate 25 is provided between the other side which is the low pressure side and the pressure receiving surface 62b of the mounting piece 62. It can be secured. On the other hand, since the inner diameter of the high-pressure side plate 24 is smaller than the inner diameter of the low-pressure side plate 25, as a result, on the inner peripheral end side of each thin plate 21 in the thin plate group, the exposed area on the high pressure side is the surface on the low pressure side. It becomes smaller than the departure area.

  Accordingly, as shown in FIG. 15A, the gas g flowing into each thin plate 21 (thin plate group) through the gap between the inner peripheral surface of the high-pressure side plate 24 and the peripheral surface of the rotary shaft 4 is the upper surface 21p of each thin plate 21. And the lower plate 21q flows widely in a diagonal direction, and a low pressure region spreads on the outer peripheral proximal end side of the thin plate 21, so that the inner peripheral end of each thin plate 21 floats from the peripheral surface of the rotating shaft 4, It flows out through the gap between the inner peripheral surface of the side plate 25 and the peripheral surface of the rotating shaft 4. Thus, the high-pressure side plate 24 and the low-pressure side plate 25 are important for the leaf seal 20 that adjusts the amount of gas flowing into each thin plate 21 and the gas pressure in order to effectively float the inner peripheral end of each thin plate 21. Fulfills the functions.

  In the leaf seal 20 described above, each thin plate 21 has a T-shape, but may have a simple rectangular shape. Further, there may be no spacer 27 between the thin plate group and the retainers 22 and 23, or the retainers 22 and 23 and the connecting member 26 may be fixed with bolts, and there is no leaf spring 28. It does not matter.

Further, when the leaf seal 20 is assembled to a large fluid machine, it is difficult to insert the leaf seal 20 into the rotary shaft 4 along the axial direction in an annular state, so that the leaf seal 20 is annular along the peripheral surface of the rotary shaft 4. As shown in FIG. 17, the configured leaf seal 20 is actually composed of a plurality of divided bodies that are divided into four to eight in the circumferential direction. At this time, the angle formed by each end face of each divided body with the circumferential surface of the rotating shaft 4 with respect to the rotation direction of the rotating shaft 4 is equal to the angle formed by each thin plate 21 with the circumferential surface of the rotating shaft 4.
JP 2002-13647 A

  By the way, in the above-described leaf seal 20, the inner diameter of the high-pressure side plate 24 is larger than the diameter of the rotating shaft 4 in order to suppress the amount of gas flowing therein to the extent that the inner peripheral end of each thin plate 21 can be levitated. The amount is slightly larger. On the other hand, shaft vibration may occur in the rotating shaft 4 depending on the operating conditions of the fluid machine. In particular, in the case of a large fluid machine, the eccentricity of the rotating shaft 4 with respect to the stator 60 (leaf seal 20) accompanying the shaft vibration is significant. Further, in a large fluid machine (for example, a gas turbine or a steam turbine) that handles a high-temperature working fluid, the entire casing of the machine is bent in the vertical direction due to a thermal effect, and thereby the stator 60 (leaf seal 20) with respect to the rotating shaft 4. ) The whole may be decentered vertically upward.

  Therefore, when the relative eccentric amount of the rotating shaft 4 becomes excessive, the peripheral surface of the rotating shaft 4 and the inner periphery of the high-pressure side plate 24 are inadvertently contacted, and the high-pressure side plate 24 itself is deformed. There is a risk of breakage. When the high-pressure side plate 24 is damaged, the gas flows excessively into the thin plate group, so that the floating action of each thin plate 21 is lost. As a result, the inner peripheral end of each thin plate 21 and the peripheral surface of the rotating shaft 4 Will be worn in a constant contact state, leading to a situation where gas leakage increases.

  Therefore, the present invention has been made in view of the above problems, and a shaft seal mechanism that employs a leaf seal that can suppress the amount of gas leakage even if the relative eccentricity of the rotating shaft occurs excessively. It is intended to provide.

  In order to achieve the above object, the shaft seal mechanism according to the present invention provides a working fluid from a high pressure side to a low pressure side in a gap between a peripheral surface of a rotating shaft and an inner peripheral surface of a stationary member that is coaxial and stationary on the rotating shaft. A shaft seal mechanism that suppresses leakage of the rotary shaft, and has a certain width in the axial direction of the rotary shaft, and each of them has an acute angle with respect to the peripheral surface of the rotary shaft with a small gap therebetween in the circumferential direction of the rotary shaft. An annular thin plate group consisting of a plurality of flexible thin plates whose inner peripheral ends are in contact with the peripheral surface of the rotating shaft when rotation is stopped, and both sides of the thin plate group in the axial direction. An annular high-pressure side plate that has an inner diameter that is a predetermined amount larger than the diameter of the rotary shaft, and that is located on the low-pressure side of both sides in the axial direction of the thin plate group. A predetermined amount larger than the inner diameter of the high-pressure side plate. A shaft seal member comprising: an annular low-pressure side plate having a diameter; an annular holding member that integrally holds the thin plate group, the high-pressure side plate, and the low-pressure side plate at their outer peripheral portions; The shaft seal mechanism attached to the above is characterized by the following points.

  As a first feature point, the high-pressure side plate is formed by stacking a plurality of annular plates each having a larger inner diameter as the plate is closer to the thin plate group, and among these annular plates, the annular plate closest to the thin plate group. The other annular plate has a protrusion that protrudes from the inner peripheral edge thereof toward the thin plate group and contacts the one side of the thin plate group. In this way, when the relative eccentricity of the rotating shaft occurs excessively, the contact of the inner periphery of the high-pressure side plate with the peripheral surface of the rotating shaft is effectively an annular plate that is separated from the thin plate group, that is, the high-pressure plate. Since it is made of an annular plate located on the side, damage to the high-pressure side plate is stopped by the high-pressure side annular plate. Therefore, even if the high-pressure side annular plate is damaged and loses its function, the low-pressure side annular plate, that is, the annular plate close to the thin plate group, can supplement the function of the high-pressure side plate and suppress the amount of gas leakage. Is possible.

  Here, when the ridge is formed separately from the annular plate and both are assembled by welding or the like, this is accompanied by an increase in the number of parts and a deterioration in the assembly work efficiency. From the viewpoint, it is preferable that the protrusion and the annular plate having the protrusion are integrally formed products.

  As a second feature point, the inner circumference of the lower half in the vertical direction of the high-pressure side plate is eccentric downward in the vertical direction. In this way, even when the relative eccentricity of the rotating shaft occurs excessively due to the entire stationary member including the shaft seal member being eccentric in the vertical direction with respect to the rotating shaft, The inner periphery of the lower half of the high-pressure side plate under the approaching condition does not contact the peripheral surface of the rotating shaft. Therefore, since the breakage of the high-pressure side plate can be avoided, the function of the high-pressure side plate can be maintained, and the amount of gas leakage can be suppressed.

  According to the shaft seal mechanism of the present invention, the function as the high-pressure side plate can be maintained even if relative eccentricity of the rotating shaft occurs excessively, and as a result, the amount of gas leakage can be suppressed.

  Hereinafter, a shaft seal mechanism employing a leaf seal as an embodiment of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view taken along the axial direction of a rotary shaft showing the main part of a large-sized fluid machine having a leaf seal of the first embodiment, and FIG. 2 is a perspective view of a high-pressure side plate that is a component of the leaf seal. . In the figure, parts having the same names and functions as in FIGS. 10 to 17 are denoted by the same reference numerals, and repeated description is omitted as appropriate, and the high-pressure side plate, which is a feature of the present invention, is noted. . The same applies to the second to fifth embodiments described later.

  As shown in FIGS. 1 and 2, the high-pressure side plate 24 is formed by stacking two annular plates 31 and 32 in the axial direction of the rotary shaft 4. The annular plate 31 (hereinafter sometimes referred to as “first annular plate” for convenience of description) is disposed on the side close to the thin plate group, and is one side that is the high-pressure side of each thin plate 21 in the thin plate group. Abut. The annular plate 32 (hereinafter sometimes referred to as “second annular plate” for convenience of description) is disposed on the side away from the thin plate group. It should be noted that the first annular plate 31 and the second annular plate 32 are, in fact, similar to the configuration of the high-pressure side plate 24 in the conventional general leaf seal 20 because of the ease of assembly to a large fluid machine. It is divided into a plurality of directions.

  Here, the first annular plate 31 and the second annular plate 32 have the same outer diameter, and project in the axial direction of the rotary shaft 4 at the outer peripheral edge portion of the first annular plate 31 in a stacked state. A protrusion 35 is provided. In the present embodiment, the protrusion 35 is not only the first annular plate 31 but also the second annular plate by spot welding or the like (the welded portion is indicated by a symbol “W1” in FIGS. 1 and 2). 32 is also fixed, so that the three parties are integrated. The protrusion 35 corresponds to the protrusion 24a (see FIG. 12) of the conventional high-pressure side plate 24, and the high-pressure side plate 24 composed of the first annular plate 31 and the second annular plate 32 is a thin plate group. When assembling to each other, it is fitted into the notch 21a of each thin plate 21 in the thin plate group. The first annular plate 31 and the second annular plate 32 in which the protrusions 35 are fitted in the notches 21 a of the thin plate group are held by the retainer 22.

  Further, the inner diameter of the second annular plate 32 is set to be the same as the inner diameter of the conventional general high-pressure side plate 24, and the inner diameter of the first annular plate 31 is greater than the inner diameter of the second annular plate 32. The fixed amount (for example, about 1 mm on one side) is set large. On the inner peripheral edge of the second annular plate 32, a ridge 38 is provided that protrudes toward the thin plate group in the axial direction of the rotary shaft 4. This protrusion 38 has the same inner diameter as the inner diameter of the second annular plate 32 and an outer diameter slightly smaller than the inner diameter of the first annular plate 31, but has the same thickness as the first annular plate 31. It has one side which is the high voltage side of each thin plate 21 in the thin plate group. In the present embodiment, the protrusion 38 is formed separately from the second annular plate 32, and is spot welded or the like (the welded portion is indicated by the symbol “W2” in FIGS. 1 and 2). ) To be fixed to the second annular plate 32, thereby integrating them.

  When the leaf seal 20 including the high-pressure side plate 24 having such a configuration is used, when the relative eccentricity of the rotary shaft 4 is excessively generated, the inner periphery of the high-pressure side plate 24 contacts the peripheral surface of the rotary shaft 4. Is actually made by the second annular plate 32 that is separated from the thin plate group, so that the breakage of the high-pressure side plate 24 is stopped by the second annular plate 32, and the first annular plate 31 can be made intact. Therefore, even if the second annular plate 32 is damaged and loses its function, the function of the high-pressure side plate 24 can be supplemented by the first annular plate 31 and the function can be maintained. It becomes possible to suppress the amount of gas leakage.

  However, in a normal state in which the second annular plate 32 does not break, one side which is a high pressure side on the inner peripheral end side of each thin plate 21 of the thin plate group is caused by the protrusion 38 which the second annular plate 32 has. Therefore, the function of the high-pressure side plate 24 is not inferior to that of the conventional high-pressure side plate 24.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a sectional view along the axial direction of the rotary shaft showing the main part of a large-sized fluid machine having a leaf seal of the second embodiment, and FIG. 4 is a perspective view of a high-pressure side plate that is a component of the leaf seal. . The feature of the second embodiment is that the configuration of the second annular plate 32 in the first embodiment is modified.

  That is, in this embodiment, as shown in FIG. 3 and FIG. 4, the protrusion 38 included in the second annular plate 32 is an integrally molded product with the second annular plate 32. In manufacturing the second annular plate 32, the outer diameter and the inner diameter of the second annular plate 32 are equal to those of the second annular plate 32 in the first embodiment, and the annular ring 32 has a constant thickness including the protrusions 38. A plate is prepared, and one side of this material is removed by etching to the same depth as the thickness of the first annular plate 31 while leaving the inner peripheral edge portion that becomes the protrusion 38 as it is. Thereby, the protrusion 38 and the 2nd annular plate 32 which has this are obtained as an integrally molded product.

  According to such a configuration, in the case of the second annular plate 32 in the first embodiment, the protrusion 38 is formed separately from the second annular plate 32, and both are welded or the like. However, in the case of the second annular plate 32 in the second embodiment, the increase in the number of parts also increases the efficiency of the assembly work by welding or the like. There is no deterioration.

  Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a sectional view along the axial direction of the rotary shaft showing the main part of a large-sized fluid machine having a leaf seal of the third embodiment, and FIG. 6 is a perspective view of a high-pressure side plate that is a component of the leaf seal. . The feature of the third embodiment is that the first and second embodiments are further modified to ensure the function as the high-pressure side plate 24 more reliably. In the high-pressure side plate 24 of the first and second embodiments, the first annular plate 31 and the second annular plate 32 are integrated including one protrusion 35, so that the second annular plate 32 When the second annular plate 32 is damaged due to the contact between the inner periphery and the peripheral surface of the rotating shaft 4, an unnecessary external force may be applied to the first annular plate 32. In FIGS. 5 and 6, a modification of the second embodiment is shown.

  In the present embodiment, as shown in FIGS. 5 and 6, the outer diameter of the first annular plate 31 is smaller than the outer diameter of the first annular plate 31 by a predetermined amount smaller than the outer diameter of the second annular plate 32. Is provided with a first protrusion 36 that protrudes in the axial direction of the rotating shaft 4, and a second protrusion that also protrudes in the axial direction of the rotating shaft 4 on the outer peripheral edge of the other second annular plate 32. 37 is provided. The first protrusion 36 is fixed to the first annular plate 31 by spot welding or the like (the welded portion is indicated by a symbol “W3” in FIGS. 5 and 6), and thereby both are integrated. . Similarly, the second protrusion 37 is fixed to the second annular plate 32 by spot welding or the like (the welded portion is indicated by a symbol “W4” in FIGS. 5 and 6), and thereby both are integrated. Is done.

  Then, the first annular plate 31 and the second annular plate 32 are stacked on each other, and in this state, the first protrusion 36 and the second protrusion 37 become one protrusion, and the first protrusion 36 and the second protrusion 37 The two protrusions 37 are fitted into the notches 21a of the thin plates 21 in the thin plate group. The first annular plate 31 and the second annular plate 32 in which the first protrusion 36 and the second protrusion 37 are fitted in the notch 21 a of the thin plate group are held by the retainer 22.

  According to such a configuration, since the first annular plate 31 and the second annular plate 32 are not effectively integrated, the inner circumference of the second annular plate 32 and the circumference of the rotating shaft 4 are not integrated. Even when the second annular plate 32 is damaged due to contact with the surface, unnecessary external force is not applied to the first annular plate 32. Therefore, the function as the high-pressure side plate 24 can be more reliably ensured with the remaining first annular plate 32. In addition, when the second annular plate 32 is damaged, the replacement is simple, and only the second annular plate 32 needs to be replaced.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a sectional view along the axial direction of the rotary shaft showing the main part of a large-sized fluid machine equipped with a leaf seal of the fourth embodiment, and FIG. 8 is a perspective view of a high-pressure side plate that is a component of the leaf seal. . The feature of the fourth embodiment is that the first to third embodiments are further modified so that the function as the high-pressure side plate 24 can be secured more flexibly. The high-pressure side plate 24 in the first to third embodiments is composed of two annular plates, the first annular plate 31 and the second annular plate 32, so that the relative eccentricity of the rotating shaft 4 is more than expected. This is because a situation in which the outer peripheral surface of the first annular plate 31 comes into contact with the peripheral surface of the first annular plate 31 is assumed. Incidentally, if the inner diameter of the first annular plate 31 is set to be much larger than the inner diameter of the second annular plate 32, contact between the inner periphery of the first annular plate 31 and the peripheral surface of the rotary shaft 4 can be avoided. However, in this case, when the second annular plate 32 is damaged, the exposed area on one side, which is the high pressure side, on the inner peripheral end side of each thin plate 21 of the thin plate group becomes excessively large. Since the function as the side plate 24 is remarkably deteriorated, it is never a good idea. In FIGS. 7 and 8, a modification of the second embodiment is shown.

  In the present embodiment, as shown in FIGS. 7 and 8, a third annular plate 33 is sandwiched between the first annular plate 31 and the second annular plate 32. That is, the high-pressure side plate 24 is formed by stacking three annular plates, the second annular plate 32, the third annular plate 33, and the first annular plate 31, in order toward the thin plate group. Here, the inner diameter of the third annular plate 33 is set to be larger than the inner diameter of the second annular plate 32 by a predetermined amount (for example, about 1 mm on one side), and the inner diameter of the first annular plate 31 is the third annular plate. A predetermined amount (for example, about 1 mm on one side) is set larger than the inner diameter of 33.

  Further, the third annular plate 33 has a configuration similar to that of the second annular plate 32, and the inner peripheral edge of the third annular plate 33 protrudes toward the thin plate group in the axial direction of the rotating shaft 4. 39 is provided. The protrusion 39 has the same inner diameter as the third annular plate 33 and an outer diameter slightly smaller than the inner diameter of the first annular plate 31, and has the same thickness as the first annular plate 31. It has one side which is the high voltage side of each thin plate 21 in the thin plate group. Here, the protrusion 38 of the second annular plate 32 has the same inner diameter as the inner diameter of the second annular plate 32 and an outer diameter slightly smaller than the inner diameter of the third annular plate 33, The third annular plate 33 has a thickness including the protrusions 37 and abuts on one side which is the high pressure side of each thin plate 21 in the thin plate group.

  In the high-pressure side plate 24 having such a configuration, when the relative eccentricity of the rotary shaft 4 occurs excessively, the contact of the inner periphery of the high-pressure side plate 24 with the peripheral surface of the rotary shaft 4 is actually a thin plate group. First, the second annular plate 32 that is farthest from the center is made, and if excessive eccentricity occurs, it is made by the third annular plate 33 that is reserved next. Therefore, the breakage of the high-pressure side plate 24 is stopped in stages by the second annular plate 32 and further by the third annular plate 33. Therefore, even if the second annular plate 32 is damaged and loses its function, the function of the high-pressure side plate 24 is supplemented by the next third annular plate 33, and the third annular plate 33 is further damaged and Even if the function is lost, the function of the high-pressure side plate 24 can be supplemented by the next first annular plate 31, and the function can be maintained flexibly.

  In the present embodiment, the high-pressure side plate 24 is formed by stacking three annular plates, but the number of sheets (the number of third annular plates 33) can be increased. However, when the number of the annular plates is increased, the inner diameter of the annular plate closer to the thin plate group becomes larger. Therefore, the function as the high-pressure side plate 24 cannot be slightly reduced. Since the exposed area on one side, which is the high-pressure side, on the inner peripheral end side of each thin plate of the group can be narrowed to the maximum, the function deterioration can be remarkably suppressed.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a plan view showing a state in which the leaf seals of the fifth embodiment of the present invention are arranged in an annular shape.

  In the fifth embodiment, as shown in FIG. 9, the lower half of the inner periphery of the high-pressure side plate 24 in the vertical direction is eccentric (offset) downward in the vertical direction. The eccentric amount d is appropriately set depending on the location where the leaf seal 20 including the high-pressure side plate 24 is installed as a shaft seal mechanism of a fluid machine.

  With such a configuration, when the entire stator 60 including the leaf seal 20 is eccentric with respect to the rotating shaft 4 in the vertical direction, the relative eccentricity of the rotating shaft 4 is excessively generated. However, the inner periphery of the lower half of the high-pressure side plate 24 in a state of approaching each other does not come into contact with the peripheral surface of the rotating shaft 4. Therefore, since the damage of the high-pressure side plate 24 can be avoided, the function of the high-pressure side plate 24 can be maintained, and the amount of gas leakage can be suppressed. This is effective for a large fluid machine (for example, a gas turbine or a steam turbine) that handles a high-temperature working fluid.

  However, in this embodiment, only the lower half of the inner periphery of the high-pressure side plate 24 is eccentric, but at the same time, the upper half is shifted upward in the vertical direction, that is, in the direction opposite to the eccentric direction of the lower half. It is also effective to have a core. In a large fluid machine, the deformation direction and amount of deformation of the entire casing may become unstable depending on the operating conditions when starting or stopping, and even in this case, the inner portion of the upper half of the high-pressure side plate 24 may be unstable. This is because contact between the periphery and the peripheral surface of the rotating shaft 4 can be prevented.

  Note that the configuration of the present embodiment can also be applied to the first to fourth embodiments.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, although the thing which employ | adopted the leaf seal is illustrated in the gas turbine shown in FIG. 10, it is not limited to it, Large-sized fluid machinery, such as a steam turbine, a compressor, a water turbine, a refrigerator, a pump, is shown. As described above, it can be widely applied to those that convert energy into work due to the relationship between the rotation of the shaft and the flow of the working fluid. It can also be used to suppress the flow of the working fluid in the axial direction along the peripheral surface of the rotating shaft.

  The present invention is useful as a shaft seal mechanism for a rotating shaft of a large fluid machine.

It is sectional drawing which follows the axial direction of the rotating shaft which shows the principal part of the large sized fluid machine provided with the leaf seal of 1st Embodiment of this invention. It is a perspective view of the high voltage | pressure side board which is a component of the leaf seal of 1st Embodiment. It is sectional drawing which follows the axial direction of the rotating shaft which shows the principal part of the large sized fluid machine provided with the leaf seal of 2nd Embodiment of this invention. It is a perspective view of the high voltage | pressure side board which is a component of the leaf seal of 2nd Embodiment. It is sectional drawing which follows the axial direction of the rotating shaft which shows the principal part of the large sized fluid machine provided with the leaf seal of 3rd Embodiment of this invention. It is a perspective view of the high voltage | pressure side board which is a component of the leaf seal of 3rd Embodiment. It is sectional drawing which follows the axial direction of the rotating shaft which shows the principal part of the large sized fluid machine provided with the leaf seal of 4th Embodiment of this invention. It is a perspective view of the high voltage | pressure side board which is a component of the leaf seal of 4th Embodiment. It is a top view which shows the state which has arrange | positioned the leaf seal of 5th Embodiment of this invention cyclically | annularly. It is the schematic which shows the structure of the gas turbine which is an example of the large sized fluid machine provided with the conventional general leaf seal. It is a perspective view which shows the basic composition of the conventional general leaf seal. It is sectional drawing which follows the axial direction of the rotating shaft which shows the principal part of the large sized fluid machine provided with the conventional general leaf seal. It is the side view and sectional drawing which follow the circumferential direction of the rotating shaft which shows the basic composition of the conventional general leaf seal. It is a side view of the thin plate which is a component of the conventional general leaf seal. It is a schematic diagram for demonstrating the effect | action of the conventional general leaf seal. It is a schematic diagram for demonstrating the effect | action of the conventional general leaf seal. It is a top view which shows the state which has arrange | positioned the conventional general leaf seal in cyclic | annular form.

Explanation of symbols

4 Rotating shaft 20 Leaf seal 21 Thin plate 22, 23 Retainer 24 High pressure side plate 25 Low pressure side plate 26 Connection member 27 Spacer 28 Leaf spring 31, 32, 33 Annular plate 35, 36, 37 Projection 38, 39 Projection 60 Stator 61 Mounting Recessed groove 62 Mounting piece

Claims (3)

A shaft seal mechanism that suppresses leakage of working fluid from the high pressure side to the low pressure side in the gap between the peripheral surface of the rotating shaft and the inner peripheral surface of a stationary member that is coaxial and stationary with respect to the rotating shaft,
Each inner peripheral end rotates while having a certain width in the axial direction of the rotating shaft and being stacked at an acute angle with respect to the peripheral surface of the rotating shaft, with each having a small gap in the circumferential direction of the rotating shaft. An annular thin plate group consisting of a large number of flexible thin plates that come into contact with the peripheral surface of the rotating shaft when stopped, and one side located on the high pressure side of both sides of the thin plate group in the axial direction. An annular high-pressure side plate having an inner diameter larger than the diameter of the rotary shaft by contact with the other side located on the low-pressure side of both sides of the thin plate group in the axial direction, and the inner diameter of the high-pressure side plate A shaft seal member comprising: an annular low-pressure side plate having an inner diameter larger than the predetermined amount; an annular holding member that integrally holds the thin plate group, the high-pressure side plate, and the low-pressure side plate at their outer peripheral portions. A shaft sealing machine attached to the stationary member In,
The high-pressure side plate is formed by stacking a plurality of annular plates each having a larger inner diameter as it is closer to the thin plate group. Among these annular plates, the annular plates other than the annular plate closest to the thin plate group are included therein. A shaft seal mechanism comprising a protrusion protruding from a peripheral edge toward the thin plate group and abutting against the one side of the thin plate group.   The shaft seal mechanism according to claim 1, wherein the protrusion and the annular plate having the protrusion are integrally formed. A shaft seal mechanism that suppresses leakage of working fluid from the high pressure side to the low pressure side in the gap between the peripheral surface of the rotating shaft and the inner peripheral surface of a stationary member that is coaxial and stationary with respect to the rotating shaft,
Each inner peripheral end rotates while having a certain width in the axial direction of the rotating shaft and being stacked at an acute angle with respect to the peripheral surface of the rotating shaft, with each having a small gap in the circumferential direction of the rotating shaft. An annular thin plate group consisting of a large number of flexible thin plates that come into contact with the peripheral surface of the rotating shaft when stopped, and one side located on the high pressure side of both sides of the thin plate group in the axial direction. An annular high-pressure side plate having an inner diameter larger than the diameter of the rotary shaft by contact with the other side located on the low-pressure side of both sides of the thin plate group in the axial direction, and the inner diameter of the high-pressure side plate A shaft seal member comprising: an annular low-pressure side plate having an inner diameter larger than the predetermined amount; an annular holding member that integrally holds the thin plate group, the high-pressure side plate, and the low-pressure side plate at their outer peripheral portions. A shaft sealing machine attached to the stationary member In,
A shaft seal mechanism, wherein an inner periphery of a lower half in the vertical direction of the high-pressure side plate is eccentric downward in the vertical direction.

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