JP5178385B2 - Rotating shaft sealing device - Google Patents

Description

  The present invention relates to a rotary shaft sealing device used in a rotary machine.

  In a rotary machine using gas or liquid as a working fluid, a rotary shaft sealing device having a non-rotating side sliding member divided into a plurality in the circumferential direction is used. This rotary shaft sealing device has a function of a dynamic pressure seal provided in a portion where a rotary body such as a rotary shaft penetrates a pressure partition inside the rotary machine, and the pressure difference between the high pressure side and the low pressure side is Used in the resulting part.

FIG. 8 is a diagram for explaining a rotary machine using a conventional rotary shaft sealing device.
In a rotating machine such as a steam turbine, a rotating body 102 having a rotating shaft 101 is rotated by a working fluid such as steam indicated by an arrow, and kinetic energy is obtained from the end of the rotating shaft, or the rotating shaft is rotated to rotate the working fluid. Energy is transmitted to and used for various purposes. Therefore, the pressure of the working fluid filled in the machine is often different from the outside air pressure where the machine is installed. Also, in the case of a multistage axial flow turbomachine or the like inside the machine, it is divided into a plurality of chambers having different pressures such as a high pressure chamber 103 and a low pressure chamber 104, and a pressure partition 105 is provided at each boundary. In order to arrange the rotary shaft 101 inside the pressure vessel 106 or the pressure chamber, the rotary shaft 101 must pass through the pressure vessel or each pressure partition, and in order to prevent leakage of the working fluid from the through hole. The rotary shaft sealing device 107 is required. A rotary shaft sealing device having a function of a dynamic pressure seal has also been used conventionally (see Patent Documents 1 to 3), and this will be described below.

FIG. 9 is a cross-sectional view of a conventional rotary shaft sealing device.
A rotating side sliding member 201 is attached to the rotating shaft 203, and the rotating side sliding member 201 rotates integrally with the rotating shaft 203. A part of the rotation shaft 203 may be used as the rotation side sliding member 201 in a steam turbine or the like. A holder 204 fixed to the casing is installed on the outer peripheral side of the rotating side sliding member 201, and an arcuate non-rotating side sliding member 202 is attached so as to surround the rotating side sliding member 201. Yes. Further, the non-rotating sliding member 202 is arranged on the outer peripheral side of the non-rotating sliding member 202 in the circumferential direction by an elastic body 205 composed of, for example, a coil spring and the like, and radially with respect to the outer peripheral surface of the rotating side sliding member 201 Or a seal gap 206 of several μm to several tens μm is maintained. The non-rotating side sliding member 202 may be pressed in the axial direction against the holder 204 by a spring.

FIG. 10 is a front view illustrating a divided shape of a non-rotating side sliding member of a conventional rotary shaft sealing device.
The non-rotating side sliding member 202 is divided into a plurality of parts in the circumferential direction, and the sliding contact surface 207 of the adjacent non-rotating side sliding member 202 is a plane that forms a straight line in the radial direction. The divided piece of each non-rotating side sliding member 202 has an arch shape that surrounds the outer diameter arc surface 208 and the inner diameter arc surface 209 with the sliding contact surface 207. Since the non-rotating sliding member 202 is divided in the circumferential direction, the assembly and maintenance of the device are excellent.

  Some of the divided pieces of the non-rotating side sliding member 202 have a structure in which a dynamic pressure pocket is provided on the inner peripheral surface in order to easily generate dynamic pressure in the seal gap 206 forming the seal portion.

FIG. 11 is a front view of a rotary shaft sealing device having a conventional dynamic pressure pocket.
12A and 12B are views for explaining a seal portion of a rotary shaft sealing device having a dynamic pressure pocket. FIG. 12A is a development view of the seal portion of the non-rotating sliding member (a view taken along the line AA in FIG. 11). ) Is a cross-sectional view (BB cross-sectional view of (a)) when the seal portion is developed on a plane, and (c) is a diagram showing a distribution of dynamic pressure generated in the seal gap.

As shown in FIGS. 11 and 12 (a) to 12 (c), each divided piece of the non-rotating side sliding member 202 has a sealing fluid which is a dynamic pressure pocket on the inner peripheral surface facing the outer surface of the rotating shaft. A seal fluid pressurizing pocket 211 is formed which is connected to the inlet pocket 210 and the rotation downstream side. The seal fluid inlet pocket 210 is a recess that is deeper than the seal fluid pressurizing pocket 211, and the side surface is open. The seal fluid, which is the working fluid of the rotating machine, easily enters the seal gap, and the amount of dynamic pressure is amplified by the seal fluid pressurizing pocket 211 that stops in the circumferential direction as shown in FIG.
Japanese Patent Laid-Open No. 9-14455 JP 2000-352467 A JP 2002-122243 A

  The conventional rotating shaft sealing device has a non-rotating side sliding member 202 divided into a plurality of parts in the circumferential direction, and has a sliding contact surface between the divided pieces of the non-rotating side sliding member, but the rotating shaft rotates. As a result, a dynamic pressure is generated in the seal gap 206 between the surface of the rotating shaft and the inner surface of the non-rotating-side sliding member divided piece, and a sealing function that prevents leakage of fluid inside the machine is exhibited.

FIG. 13 is a diagram illustrating a state where the divided pieces of the non-rotating side sliding member move to the outer diameter side.
During the rotation of the rotating shaft 203, the divided piece of the non-rotating side sliding member 202 receives dynamic pressure on its inner peripheral surface and receives a force toward the radially outer diameter side. On the other hand, the divided piece of the non-rotating side sliding member 202 is wound around the outer periphery by an elastic body 205 and receives a pressing force toward the inner side in the radial direction. The divided pieces of the sliding member 202 move to the outer diameter side in the radial direction.

The divided pieces of the non-rotating side sliding member 202 have a larger diameter when moved in the radial direction. However, since the circumferential length of each non-rotating side sliding member 202 does not change, each sliding contact surface 207 A gap 212 is formed.
Therefore, the fluid inside the machine blows through the sliding contact surface 207 between the divided pieces of the non-rotating side sliding member 202, and leakage occurs.

  Therefore, even when dynamic pressure is generated in the seal gap 206 and the sealing function is exerted, the shape or structure is such that the gap 212 is not formed on the sliding contact surface 207 between the divided pieces of the non-rotating side sliding member 202. It has been a challenge to reduce the amount of leakage.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary shaft sealing device that can reduce the amount of fluid leakage from a sliding contact surface so that there is no gap on the sliding contact surface between divided pieces of a non-rotating side sliding member. There is.

In order to solve the above problems, a rotating shaft sealing device of the present invention is wound around a ring-shaped non-rotating side sliding member divided into a plurality of portions in the circumferential direction and the outer periphery of the non-rotating side sliding member. A rotary shaft sealing device for a rotary machine, which comprises an elastic body that presses toward the inner peripheral side, and forms a seal gap between the inner peripheral surface of the non-rotating side sliding member and the outer surface of the rotary shaft during rotation. The sliding contact surfaces of the divided pieces of the adjacent non-rotating side sliding members are flat or curved, and are inclined in the rotation direction of the rotation axis with respect to the radial axis, and the non-rotating side sliding during rotation. The seal gap on the upstream side of each divided piece of the moving member is wider than the seal gap on the downstream side .

  According to the present invention, there is no gap between the sliding contact surfaces of the adjacent divided pieces of the non-rotating side sliding member, and the amount of fluid leakage from the sliding contact surface can be reduced.

An embodiment of a rotary shaft sealing device according to the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a front view showing a divided shape of a non-rotating side sliding member of a rotating shaft sealing device according to Embodiment 1, and FIG. 2 is a non-rotating side sliding member when dynamic pressure is generated in the rotating shaft sealing device. It is a front view showing the state to which the divided piece moves.

  In FIG. 1, a holder fixed to the casing is installed on the rotating shaft of a rotating machine such as a steam turbine, that is, the outer peripheral side of the rotating side sliding member 1, and the non-rotating sliding so as to surround the rotating side sliding member 1. The member 2 is arranged in a ring shape. The non-rotating sliding member 2 is composed of a plurality of divided pieces in the circumferential direction. A seal portion is provided between the outer surface of the rotating shaft and the inner peripheral surface of the non-rotating side sliding member 2, and a constant seal gap 6 is provided in the radial direction in the same manner as in the conventional rotating shaft sealing device. The divided pieces of the adjacent non-rotating side sliding members 2 are in contact with the sliding contact surface 7 so that the sliding contact surface 7 is a surface inclined with respect to the radial axis L. The divided piece of each non-rotating side sliding member 2 has an arch shape that surrounds the outer diameter arc surface 8 and the inner diameter arc surface 9 with the sliding contact surface 7. The non-rotating side sliding member 2 is prevented from rotating by a pin (not shown) with respect to the holder.

  As the rotation-side sliding member 1 rotates, a dynamic pressure is generated in the seal gap 6 and the high-pressure side fluid is prevented from blowing through to the low-pressure side. At the same time, the divided pieces of the non-rotating side sliding member 2 try to move to the outer peripheral side by receiving dynamic pressure on the inner peripheral surface. On the other hand, the outer peripheral side of the split piece of the non-rotating-side sliding member 2 is wound with an elastic body 5 such as a coil spring to receive a pressing force toward the inner peripheral side as in the conventional case. Therefore, the divided piece of the non-rotating side sliding member 2 moves in the radial direction to a position where the dynamic pressure acting on the inner circumferential surface and the pressing force acting on the outer circumference balance, and the seal gap 6 is widened. At this time, since the divided pieces move along the sliding contact surface 7 when moving in the radial direction, they are inclined with respect to the radial direction and moved to the outer peripheral side as shown in FIG. Keep. Since the sliding surface 7 is inclined, almost surface contact can be achieved.

  Further, since the slidable contact surface 7 is inclined in the rotational direction of the rotation axis with respect to the radial axis L, when the divided piece moves toward the radially outer peripheral side while being inclined along the slidable contact surface 7, as shown in FIG. In addition, the seal gap 6a on the upstream side of the split piece is wider than the seal gap 6b on the downstream side.

  The split piece of the non-rotating sliding member 2 has a sealing fluid inlet pocket and a sealing fluid boosting pocket as dynamic pressure pockets on the inner peripheral surface facing the outer surface of the rotating shaft, as in the conventional rotating shaft sealing device (FIG. 11). However, in the present invention, the shape and arrangement are devised in order to control the dynamic pressure so that the divided pieces are inclined.

3A and 3B are diagrams for explaining the dynamic pressure pockets of the seal portion of the non-rotating sliding member. FIG. 3A is a cross-sectional view showing an example of the shape, and FIG. 3B is a diagram showing a distribution of dynamic pressure generated in the seal gap. .
As shown in FIG. 3A, the shape and arrangement of the dynamic pressure pocket including the seal fluid inlet pocket 10 and the seal fluid pressurizing pocket 11 connected to the rotation downstream side are adjusted. For example, as compared with the dynamic pressure pocket (FIG. 12) of the conventional rotary shaft seal device, the overall circumferential dimension is shortened, the position is shifted to the downstream side of the rotation, and the end of the seal fluid boost pocket 11 is inclined. Is attached. As a result, as shown in FIG. 3B, the distribution of the dynamic pressure generated in the seal gap is adjusted, and the center position of the force for moving the divided piece radially outward is shifted from the center of the divided piece to the upstream side in the circumferential direction. By shifting, the split piece can be actively tilted.

  As described above, even when dynamic pressure is generated in the seal gap 6 and the sealing function is exerted, the divided pieces of the non-rotating side sliding member 2 are kept in contact with the sliding contact surface 7, so that the sliding between the divided pieces is maintained. It is possible to eliminate the gap between the contact surfaces 7 and prevent blow-through from between the divided pieces, thereby reducing the amount of fluid leakage. Further, since the seal gap 6a on the upstream side of the split piece is wider than the seal gap 6b on the downstream side, it becomes easy to entrain the seal fluid in the seal gap due to rotation, and the generation of dynamic pressure in the seal gap 6 is facilitated. The amount can be reduced.

FIG. 4 is a diagram showing the inclination angle of the sliding surface and the increased leakage amount ratio.
As shown in FIG. 1, the slidable contact surface 7 is a flat surface, and the inclination with respect to the radial axis L is in the range of 10 ° to 70 ° on the downstream side of the divided piece.

  The split piece moves radially outward while tilting in the range of 10 ° to 70 ° along the sliding contact surface 7, and the seal gap 6a on the upstream side of the split piece as shown in FIG. Within a larger range than the seal gap 6b on the downstream side of the rotation.

As shown in FIG. 4, when the inclination angle of the sliding surface 7 is 0 ° to 10 °, the inclined angle of the sliding surface 7 when the divided piece moves radially outward while inclining while maintaining the contact with the sliding surface 7. Is small, it is difficult to maintain the contact state, and a gap between the divided pieces is likely to occur, and the amount of fluid leakage increases. On the other hand, when the slidable contact surface is in the range of 70 ° to 90 °, the contact state of the slidable contact surface 7 is easily maintained when the split piece moves radially outward, but the same as the angle of the slidable contact surface 7 increases. The difference between the seal clearances 6a and 6b between the upstream side of the rotation and the downstream side of the rotation is large even when the travel distance is radially outward. For this reason, since the seal gap 6a on the rotation upstream side becomes too wide, the dynamic pressure generated in the seal gap 6 is not maintained, the amount of blow-through in this range increases, and the amount of fluid leakage increases.
When the inclination angle of the sliding contact surface is in the range of 10 ° to 70 °, the increase in the leakage amount can be prevented.

(Embodiment 2)
FIG. 5 is a front view illustrating a divided shape of the non-rotating side sliding member of the rotary shaft sealing device according to the second embodiment.

  In the present embodiment, as shown in FIG. 5, the sliding contact surface 7 of the divided piece of the non-rotating side sliding member 2 is a curved surface inclined with respect to the radial axis, and the curved surface has, for example, a radius of curvature in the radial direction. Try to increase.

When the divided pieces of the non-rotating sliding member 2 move in the radial direction, the non-rotating sliding member 2 moves along the curved sliding contact surface and maintains the contact state between the sliding contact surfaces.
As a result, each divided piece moves radially outward while inclining when dynamic pressure is generated in the seal gap 6. However, since the sliding surface 7 is curved, the movement is smooth and the sliding surface 7 is in a contact state. In addition, it is easy to maintain the contact, and the surface contact can be almost achieved at the sliding contact surface 7. Therefore, it is possible to prevent an increase in leakage amount.

(Embodiment 3)
6A and 6B are diagrams illustrating a non-rotating side sliding member of the rotary shaft sealing device according to the third embodiment, in which FIG. 6A is a front view illustrating a divided shape, and FIG. 6B is a diagram illustrating a shape of a sliding contact surface. It is.

  In the present embodiment, the divided piece of the non-rotating sliding member includes the sliding contact surface 7 in addition to the shape of the sliding contact surface 7 of the divided piece of the non-rotating sliding member 2 in the first or second embodiment. And as shown in FIG.6 (b), it has the level | step difference 12 of the axial direction, and has a shape which mutually fits.

Since the slidable contact surface 7 has a step in the axial direction, the contact state of the slidable contact surface 7 can be maintained regardless of the position of the split piece in the radial direction.
Thereby, there is no gap in the sliding contact surface 7 between the divided pieces, and the amount of leakage can be reduced.

FIG. 7 is a diagram illustrating another shape of the sliding contact surface of the non-rotating side sliding member.
In addition to the shape of the sliding contact surface 7 of the split piece in the non-rotating sliding member 2 of Embodiment 1 or 2, the sliding contact surface 7 has a shape having a convex portion 13 in the circumferential direction and a concave portion 14 fitted thereto. ing.

Since the slidable contact surface 7 has an uneven portion that fits in the circumferential direction, the contact state of the slidable contact surface 7 in the axial direction can be maintained regardless of the radial position of the divided pieces.
Thereby, there is no gap in the sliding contact surface 7 between the divided pieces, and the amount of leakage can be reduced.

The front view showing the division | segmentation shape of the non-rotation side sliding member of the rotating shaft sealing apparatus which concerns on Embodiment 1. FIG. The front view showing the state which the division piece of a non-rotation side sliding member moves when dynamic pressure arises in a rotating shaft sealing device. It is a figure explaining the dynamic pressure pocket of the seal | sticker part of a non-rotation side sliding member, (a) is sectional drawing showing an example of a shape, (b) is a figure which shows the dynamic pressure distribution which arises in a seal clearance gap. The figure which shows the inclination-angle of a sliding surface, and the increase leakage amount ratio. The front view showing the division | segmentation shape of the non-rotation side sliding member of the rotating shaft sealing apparatus which concerns on Embodiment 2. FIG. It is a figure explaining the non-rotation side sliding member of the rotating shaft sealing apparatus which concerns on Embodiment 3, (a) is a front view showing division | segmentation shape, (b) is a figure showing the shape of a sliding contact surface. The figure showing the other shape of the sliding contact surface of a non-rotation side sliding member. The figure explaining the rotary machine using the conventional rotating shaft sealing apparatus. Sectional drawing of the conventional rotating shaft sealing apparatus. The front view showing the division | segmentation shape of a non-rotation side sliding member. The front view of the rotating shaft sealing apparatus with the conventional dynamic pressure pocket. It is a figure explaining the seal part of the rotating shaft sealing apparatus with a dynamic pressure pocket, (a) is an expanded view (AA arrow view of FIG. 11) of the seal part of a non-rotating sliding member, (b) is a seal part. Sectional drawing when (2) is developed on the plane (BB sectional view of (a)), (c) is a diagram showing the distribution of the dynamic pressure generated in the seal gap. The figure showing the state which the division piece of a non-rotation side sliding member moves to an outer-diameter side.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotation side sliding member (rotating shaft), 2 ... Non-rotation side sliding member, 5 ... Elastic body, 6 ... Seal gap, 7 ... Sliding contact surface, 8 ... Outer diameter arc surface, 9 ... Inner diameter arc surface, DESCRIPTION OF SYMBOLS 10 ... Seal fluid inlet pocket, 11 ... Seal fluid pressurization pocket, 12 ... Axial step, 13 ... Axial convex part, 14 ... Axial concave part.

Claims (6)

The ring-shaped non-rotating side sliding member divided into a plurality of parts in the circumferential direction, and an elastic body wound around the outer periphery of the non-rotating side sliding member and pressed toward the inner periphery side, In the rotary shaft sealing device for a rotary machine that forms a seal gap between the inner peripheral surface of the non-rotating side sliding member and the outer surface of the rotary shaft,
The sliding surfaces of the divided pieces of the adjacent non-rotating side sliding members are flat or curved, and are inclined in the rotation direction of the rotation axis with respect to the radial axis, and the non-rotating side sliding during rotation. A rotary shaft seal device, wherein a seal clearance on the upstream side of each divided piece of the member is wider than a seal clearance on the downstream side of rotation. The rotary shaft sealing device according to claim 1 , wherein the sliding contact surface is a flat surface and is inclined by 10 ° to 70 ° in the rotation direction of the rotary shaft with respect to the radial axis. Each of the divided pieces of the non-rotating side sliding member forms a dynamic pressure pocket including a seal fluid inlet pocket and a seal fluid pressurizing pocket connected to the rotation downstream side on an inner peripheral surface facing the outer surface of the rotation shaft, and the dynamic pressure pocket, shaped like deviate in the circumferential direction to the rotation upstream side from the center of the center position of the force to move the split pieces radially outwardly divided piece, according to claim 1 or 2, characterized in that the arrangement Rotating shaft sealing device. The rotary shaft sealing device according to claim 3 , wherein an end portion of the dynamic pressure pocket is inclined. The rotary shaft sealing device according to any one of claims 1 to 4 , wherein the sliding contact surface has a step in an axial direction. 6. The rotary shaft sealing device according to claim 5 , wherein the step in the axial direction has a concave shape in which one is convex and the other is fitted in the circumferential direction.

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