JP6233643B2 - SEALING DEVICE AND ROTARY MACHINE WITH THE SAME - Google Patents

Description

  The present invention relates to a sealing device and a rotary machine including the same.

  A rotary machine such as a centrifugal compressor generally has a gap between a rotating body such as a rotating shaft and a stationary body such as a casing around the rotating body. Therefore, in many cases, a seal device that suppresses the inflow of the working fluid is provided in the gap between the rotating body and the stationary body. In the case of a centrifugal compressor, the sealing device is provided at a cap portion at the inlet of the impeller, between each stage of the multistage impeller, and a balance piston portion provided at the final stage of the multistage impeller. For example, a damper seal or a labyrinth seal is used for such various sealing devices.

The labyrinth seal is provided with a plurality of projecting portions that project toward the rotating shaft from an annular stationary side member facing the rotating rotating shaft with a gap. In this labyrinth seal, fluid leakage can be reduced by causing pressure loss in the fluid flowing near the tip of the protrusion. In addition, as the damper seal, a honeycomb seal, a hole pattern seal, and the like are known. For example, in the hole pattern seal, an annular stationary side member arranged with a gap from the rotation shaft faces the rotation shaft. A plurality of holes are formed in the hole, and fluid leakage can be reduced by pressure loss generated in the holes.
The damper seal has a greater damping effect than the labyrinth seal and is advantageous in terms of stabilizing the vibration of the rotating shaft, whereas the labyrinth seal can further reduce the amount of fluid leakage compared to the damper seal.

  By the way, the rotating shaft of a rotating machine is supported by a bearing. However, if the destabilizing force generated by the above-described sealing device or impeller becomes larger than the damping force obtained by the bearing, the rotation determined by the load, the rotational speed, etc. Unstable vibration occurs at the natural frequency of the machine, and the rotating shaft swings. In view of such a problem, by making the bearing rigidity different in the circumferential direction, the bearing shaft has anisotropy (anisotropic rigidity) and the rotation shaft is intentionally swung around in an elliptical shape. Thus, a technique for suppressing unstable vibration of the rotating shaft is adopted.

  On the other hand, seal devices using labyrinth seals, damper seals, etc. generally have uniform circumferential rigidity (having isotropic rigidity), and basically have anisotropic rigidity. Not done. Therefore, when such a sealing device is applied to the rotating shaft that swings in an elliptical shape as described above, the isotropic rigidity of the sealing device acts to weaken the anisotropic rigidity of the bearing. As a result, there is a possibility that unstable vibration of the rotating shaft cannot be suppressed.

  Therefore, Patent Document 1 discloses a sealing device that provides anisotropy to the pressure applied to the rotating shaft. The swirl flow prevention device, which is a sealing device described in Patent Document 1, has an inner peripheral surface of a labyrinth packing that is a main body of a labyrinth seal formed in an elliptical shape. In this swirl prevention device, the size of the gap between the inner peripheral surface and the outer peripheral surface of the rotating shaft is changed by disposing the center of the labyrinth packing with respect to the rotating shaft. Thereby, anisotropy is generated in the pressure applied to the rotating shaft from the fluid flowing through the gap, and unstable vibration of the rotating shaft is suppressed.

JP-A-2005-214144

  However, the sealing device described in Patent Document 1 has a problem that the gap between the rotating shaft and the sealing device becomes large, so that the leakage flow rate increases and the sealing effect decreases.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a sealing device capable of obtaining a sealing effect while suppressing unstable vibration of a rotating shaft, and a rotary machine including the same. And

In order to solve the above problems, the present invention proposes the following means.
The sealing device in the first aspect of the present invention is a sealing device that seals the flow of fluid in the direction along the axis of the rotary shaft on the outer peripheral surface of the rotary shaft over the entire circumference of the outer peripheral surface of the rotary shaft. The first seal portion facing the outer circumferential surface of the rotating shaft and uniformly formed in the circumferential direction of the rotating shaft, and facing the outer circumferential surface of the rotating shaft and changing the structure in the circumferential direction of the rotating shaft and a second seal portion formed to the second sealing portion, said at least one found provided on the side in the axial direction of the first seal portion is, the second seal portion, the peripheral of the rotary shaft A plurality of fin portions that are arranged side by side in the direction and extend toward the outer peripheral surface of the rotating shaft, and the fin portions are arranged such that the interval between the fin portions adjacent to each other in the circumferential direction of the rotating shaft is the circumference of the rotating shaft. It is provided to change in the direction .

According to such a sealing device, since the second seal portion is formed so as to change the structure in the circumferential direction of the rotating shaft, the rigidity acting on the rotating shaft due to the leakage flow is increased in the circumferential direction of the rotating shaft. Depending on the position, it can be operated in different states. That is, anisotropy can be generated in the rigidity of the second seal portion. As a result, it is possible to suppress the unstable vibration generated in the rotating shaft by intentionally swinging the rotating shaft into an elliptical shape and maintaining this swinging. In addition, since the first seal portion that is uniformly formed in the circumferential direction with respect to the rotation shaft is disposed, it is possible to reduce the amount of fluid that leaks only by the second seal portion.
Moreover, according to such a sealing device, the number of fin portions arranged in the circumferential direction is different by changing the interval between the fin portions adjacent in the circumferential direction in the circumferential direction. Therefore, at the position where the number of fin portions is small, there are few fin portions that block the leakage swirl flow, so that the effect of reducing the leakage swirl flow velocity is reduced. On the other hand, at a position where the number of fin portions is large, since there are many fin portions that block the leakage swirl flow, the effect of reducing the leakage swirl flow rate is increased. That is, the leakage swirl velocity near the outer peripheral surface of the rotating shaft is small at a position with few fin portions, and the leakage swirling flow velocity near the outer peripheral surface of the rotating shaft is large at a position with many fin portions. Therefore, anisotropy can be generated in the rigidity acting on the rotating shaft due to the leakage swirl flow. Therefore, the second seal portion having anisotropy can be easily formed.

  In the sealing device according to another aspect of the present invention, the second seal portion may be provided on the high pressure side of the first seal portion.

  According to such a sealing device, since the second seal portion is provided on the high pressure side of the first seal portion, the fluid can flow into the second seal portion before the first seal portion. By allowing the fluid to flow from the second seal portion, anisotropy can be generated in the rigidity generated by the first seal portion. As a result, it is possible to more effectively suppress unstable vibration generated in the rotating shaft by intentionally swinging the rotating shaft into an elliptical shape and stably maintaining the swing.

  Furthermore, in the sealing device according to another aspect of the present invention, the second seal portion may change the distance from the outer peripheral surface of the rotating shaft in the circumferential direction of the rotating shaft.

  According to such a sealing device, the distance between the second seal portion and the outer peripheral surface varies in the circumferential direction by changing the distance from the outer peripheral surface of the rotating shaft in the circumferential direction. For this reason, at a position where the distance is large, the flow rate of the fluid flowing in increases, and the pressure acting on the rotating shaft due to the leakage flow decreases. On the other hand, at a position where the distance is small, the flow rate of the flowing fluid decreases, and the pressure acting on the rotating shaft increases due to the leakage flow. Therefore, the rigidity acting on the rotating shaft by leakage flow is such that the pressure acting on the rotating shaft is small at a position where the distance from the outer peripheral surface is large and the pressure acting on the rotating shaft is large at a position where the distance from the outer peripheral surface is small. Can cause anisotropy. Therefore, the second seal portion having anisotropy can be easily formed.

  Furthermore, in the sealing device according to another aspect of the present invention, the second seal portion may change the length in the axial direction in the circumferential direction of the rotating shaft.

  According to such a sealing device, the energy loss of the fluid flowing through the second seal portion varies in the circumferential direction by changing the length in the axial direction in the circumferential direction. Therefore, energy loss increases at a position where the length in the axial direction is long. On the other hand, energy loss is small at positions where the length in the axial direction is short. Therefore, anisotropy can be generated in the rigidity acting on the rotating shaft due to the leakage axial flow. Therefore, the second seal portion having anisotropy can be easily formed.

  Furthermore, the rotating machine according to the second aspect of the present invention can suppress unstable vibration of the rotating shaft, and can improve efficiency as a rotating machine by reducing leakage and improve performance.

  According to the sealing device of the present invention, the first seal portion formed uniformly in the circumferential direction of the rotating shaft and the second seal portion formed so as to change the structure in the circumferential direction of the rotating shaft are arranged in the axial direction. By arranging them, it is possible to obtain a sealing effect while suppressing unstable vibration of the rotating shaft.

It is sectional drawing which shows the rotary machine in 1st embodiment of this invention. It is sectional drawing which looked at the sealing device and rotating shaft in 1st embodiment of this invention from the axial direction. It is AA sectional drawing of FIG. 2 which shows the sealing device and rotating shaft in 1st embodiment of this invention. It is sectional drawing which looked at the sealing device and rotating shaft in 2nd embodiment of this invention from the axial direction. It is AA sectional drawing of FIG. 4 which shows the sealing device and rotating shaft in 2nd embodiment of this invention. It is sectional drawing which looked at the sealing device and rotating shaft in 3rd embodiment of this invention from the axial direction. It is sectional drawing which shows the sealing apparatus and rotating shaft in 3rd embodiment of this invention, The figure (a) is AA sectional drawing of FIG. 6, The same figure (b) is BB sectional drawing of FIG. It is. It is the expanded view which expand | deployed the 2nd seal | sticker part arrange | positioned at the high voltage | pressure side in 3rd embodiment of this invention from the 2nd internal peripheral surface side. It is sectional drawing which looked at the sealing device and rotating shaft in 4th embodiment of this invention from the axial direction. It is sectional drawing which shows the sealing apparatus and rotating shaft in 4th embodiment of this invention, The figure (a) is AA sectional drawing of FIG. 9, The same figure (b) is BB sectional drawing of FIG. It is. It is the expanded view which expand | deployed the 2nd seal part in 4th embodiment of this invention from the 2nd internal peripheral surface side.

<< first embodiment >>
Hereinafter, a rotary machine 1 including a sealing device 51 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
The rotating machine 1 in the present embodiment is a multistage centrifugal compressor including a plurality of impellers 4.

  The rotating machine 1 includes a rotating shaft 2 around the axis P, a bearing 3 that supports the rotating shaft 2 so as to be rotatable around the axis P, and a process gas G (attached to the rotating shaft 2 using centrifugal force. An impeller 4 that compresses the fluid), a sealing device 51 that is disposed between the impellers 4 and provided along the outer peripheral surface 2a of the rotating shaft 2, and a casing 6 that covers these from the outer peripheral side.

The rotary shaft 2 has a columnar shape and extends in the direction of the axis P, and is rotatably supported by the bearing 3 at both ends in the direction of the axis P.
One bearing 3 is provided at each end of the rotary shaft 2 and supports the rotary shaft 2 rotatably. Each of these bearings 3 is attached to a casing 6.

The impeller 4 compresses the process gas G (fluid) using centrifugal force due to rotation. This is a so-called closed impeller 4 including an impeller 4, a disk 4a, a blade 4c, and a cover 4b.
The disks 4a are each formed in a disk shape that gradually increases in diameter toward the outer side in the radial direction of the axis P toward the central position C in the direction of the axis P of the rotary shaft 2.
The blade 4c is formed so as to protrude from the disk 4a to the end side opposite to the central position C in the axis P direction. A plurality of blades 4c are formed at predetermined intervals in the circumferential direction of the axis P.
The cover 4b covers the plurality of blades 4c from the end side in the axis P direction. The cover 4b is formed in a disk shape facing the disk 4a.

  A plurality of impellers 4 are attached to the rotating shaft 2 between the bearings 3 arranged on both sides in the axis P direction. These impellers 4 constitute two sets of three-stage impeller groups 4A and 4B in which the directions of the blades 4c are opposite to each other in the axis P direction. In the three-stage impeller group 4A and the three-stage impeller group 4B, the pressure of the process gas G on the central position C side in the axis P direction is the highest. That is, the process gas G flows through the three-stage impeller group 4A and the three-stage impeller group 4B while being compressed stepwise toward the central position C in the direction of the axis P.

  The casing 6 supports the bearing 3 and covers the rotating shaft 2, the impeller 4, and the seal device 51 from the outer peripheral side. The casing 6 is formed in a cylindrical shape.

The casing 6 includes a suction port 6bA on one side in the axis P direction (left side in FIG. 1). The suction port 6bA is connected to a suction channel 6cA formed in an annular shape. The suction flow path 6cA is connected to the flow path of the impeller 4 arranged on the most side of the three-stage impeller group 4A. That is, the process gas G flowing from the suction port 6bA is introduced into the three-stage impeller group 4A via the suction flow path 6cA.

  The casing 6 includes casing flow paths 6aA and 6aB that connect the flow paths formed between the blades 4c of the impellers 4 to each other.

  The casing 6 includes a discharge port 6eA on the center position C side in the axis P direction. The discharge port 6eA is connected to a discharge channel 6dA formed in an annular shape. The discharge flow path 6dA is connected to the flow path of the impeller 4 arranged on the most other side (right side in FIG. 1) of the three-stage impeller group 4A. That is, the process gas G compressed by the impeller 4 arranged on the most other side of the three-stage impeller group 4A is discharged from the discharge port 6eA to the outside of the casing 6 through the discharge flow path 6dA.

  The casing 6 is formed so that one side and the other side in the axis P direction are symmetrical with respect to the center position C. On the other side of the casing 6, a casing channel 6aB, a suction port 6bB, a suction channel 6cB, a discharge channel 6dB, and a discharge port 6eB are formed. The three-stage impeller group 4B arranged on the other side of the casing 6 further compresses the process gas G compressed by the one-stage three-stage impeller group 4A.

That is, on the other side of the casing 6, the process gas G discharged from the discharge port 6eA is sent to the suction port 6bB. Thereafter, the process gas G flowing from the suction port 6bB is supplied to the three-stage impeller group 4B via the suction flow path 6cB and compressed in stages.
The process gas G compressed by the three-stage impeller group 4B is discharged from the discharge port 6eB to the outside of the casing 6 through the discharge channel 6dB.

As described above, the process gas G compressed in the three-stage impeller group 4A is introduced into the three-stage impeller group 4B and further compressed to reach the vicinity of the center position C. Therefore, a pressure difference is generated between the three-stage impeller group 4A and the three-stage impeller group 4B. Specifically, the three-stage impeller group 4A has a lower pressure, and the three-stage impeller group 4B has a higher pressure. Further, in the vicinity of the center position C, a space is formed between the outer peripheral surface 2 a of the rotating shaft 2 and the inner peripheral surface of the casing 6. Therefore, the process gas G passes through the space in the direction of the axis P in which the three-stage impeller group 4A is disposed, with the high-pressure side being the other side in the direction of the axis P in which the three-stage impeller group 4B is disposed upstream. It tends to flow toward the downstream of the low pressure side, which is one side.
In view of this, the sealing device 51 in this embodiment is located near the central position C in order to suppress the flow of the process gas G from the three-stage impeller group 4B on the high pressure side to the three-stage impeller group 4A on the low pressure side. Is provided.

  The sealing device 51 is provided on the outer peripheral side of the rotating shaft 2 and seals the flow of the process gas G between the three-stage impeller group 4A and the three-stage impeller group 4B. As shown in FIGS. 2 and 3, the sealing device 51 is disposed so as to face the outer peripheral surface 2 a of the rotating shaft 2 and is formed uniformly in the circumferential direction of the rotating shaft 2. A second seal portion 512 that is disposed facing the outer peripheral surface 2 a of the shaft 2 and whose structure changes in the circumferential direction of the rotating shaft 2.

  The first seal portion 511 is an annular member disposed so as to cover the outer peripheral surface 2 a of the rotating shaft 2. The first seal portion 511 is arranged so that a gap S <b> 1 for rotating the rotary shaft 2 is formed between the first seal portion 511 and the rotary shaft 2. In the first seal portion 511, a first inner peripheral surface 511 a that is a surface facing the outer peripheral surface 2 a of the rotating shaft 2 is uniformly formed in the circumferential direction of the rotating shaft 2. That is, in the first seal portion 511, the radial distance between the first inner peripheral surface 511a and the outer peripheral surface 2a is the same distance L over the entire circumference. Specifically, the first seal portion 511 of the present embodiment is formed in a cylindrical shape in which the end edge of the first inner peripheral surface 511a forms a perfect circle and extends in the axis P direction.

  The second seal portion 512 is disposed on both sides of the high pressure side and the low pressure side of the first seal portion 511. That is, the second seal portion 512 is connected side by side so as to be sandwiched from both sides in the axis P direction with respect to the first seal portion 511. The second seal portion 512 is an annular member that is disposed so as to cover the outer peripheral surface 2 a of the rotating shaft 2 and has a different structure from the first seal portion 511. The second seal portion 512 is also arranged such that a gap S <b> 2 for rotating the rotary shaft 2 is formed between the second seal portion 512 and the rotary shaft 2. As for the 2nd seal | sticker part 512, the shape of the 2nd inner peripheral surface 512a which is a surface facing the outer peripheral surface 2a of the rotating shaft 2 changes in the circumferential direction. In other words, the second seal portion 512 of the present embodiment differs in the radial distance of the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a when the circumferential position is different.

  The second seal portion 512 gradually increases in diameter as the second inner peripheral surface 512a moves from the first seal portion 511 side toward the high pressure side or the low pressure side along the axis P direction. In the second seal portion 512 of the present embodiment, the radial distance between the second inner peripheral surface 512a and the outer peripheral surface 2a at the boundary with the first seal portion 511 in the axis P direction is the same as the first inner peripheral surface 511a. It is formed so as to be equidistant L in line with the radial distance from the outer peripheral surface 2a.

  Specifically, the second inner peripheral surface 512a of the second seal portion 512 is at least on the high-pressure side or the low-pressure side, and the radial distance between the second inner peripheral surface 512a and the outer peripheral surface 2a is the first seal portion 511. It is formed so as to gradually spread from the same equidistant position L toward the circumferential direction.

  More specifically, in the second seal portion 512 disposed on the high pressure side of the first seal portion 511 of the present embodiment, the first end that is the edge of the second inner peripheral surface 512a on the high pressure side in the axis P direction. In the shape of the edge 512b viewed from the direction of the axis P, the radial distance at the position of the upper end or the lower end in the vertical direction is equal distance L. The shape of the first end edge 512b viewed from the direction of the axis P is such that the radial distance increases toward the positions of both ends in the horizontal direction that are 90 degrees different from the positions of the upper end or the lower end in the circumferential direction. It is formed in a long oval shape.

  And in the 2nd seal part 512 arrange | positioned at the high voltage | pressure side of the 1st seal part 511, the 2nd edge 512c which is an edge of the 2nd internal peripheral surface 512a in the 1st seal part 511 side of the axis line P direction is set to an axis line. The shape viewed from the P direction is the same as the first inner peripheral surface 511a in the distance from the outer peripheral surface 2a, and is formed in a perfect circle shape with an equal distance L.

  Moreover, in the 2nd seal part 512 arrange | positioned at the low voltage | pressure side of the 1st seal part 511, it arrange | positions in the state which reversed the 2nd seal part 512 arrange | positioned on the high voltage | pressure side on both sides of the 1st seal part 511. In other words, in the second seal portion 512 disposed on the low pressure side, the first end edge 512b is disposed on the low pressure side in the axis P direction, and the second end edge 512c is disposed on the first seal portion 511 side in the axis P direction.

Next, the operation of the sealing device 51 having the above configuration will be described.
In the rotary machine 1 as described above, by compressing the process gas G that is a fluid, the outer peripheral surface 2a of the rotary shaft 2, the second inner peripheral surface 512a of the second seal portion 512, and the first seal portion 511 are first. Part of the process gas G also flows into the gaps S1 and S2 between the inner peripheral surface 511a and a leakage flow in the direction of the axis P is formed in a spiral around the outer peripheral surface 2a of the rotating shaft 2. This leakage flow is constituted by a leakage swirl flow that is a circumferential component toward the rotation direction R of the rotation shaft 2 and a leakage axial flow that is a component toward the axis P direction of the rotation shaft 2. In the rotary machine 1 of the present embodiment, the process gas G causing this leakage flow is the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a from the high pressure side in the axis P direction, the first By flowing sequentially into the gap S1 between the inner peripheral surface 511a and the outer peripheral surface 2a and the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a, the upstream side along the axis P direction of the rotary shaft 2 The process gas G is prevented from flowing out from the downstream side.

  According to the sealing device 51 as described above, the second seal portion 512 is formed so as to change the shape of the second inner peripheral surface 512a in the circumferential direction of the rotating shaft 2, thereby leaking the process gas G. The rigidity acting on the rotary shaft 2 by the flow can be made to act in different states depending on the circumferential position of the rotary shaft 2. That is, anisotropy can be generated in the rigidity of the second seal portion 512. As a result, the rotating shaft 2 can be intentionally swung in an elliptical shape, and unstable vibration generated in the rotating shaft 2 can be suppressed by maintaining this swinging. In particular, the first seal portion 511 and the second seal portion 512 are adjacent to and close to the axis P direction, so that the rigidity of the second seal portion 512 is more effectively anisotropic. Can be made. In addition, the first seal portion 511 that is uniformly formed so that the first inner peripheral surface 511a has a constant interval in the circumferential direction with respect to the outer peripheral surface 2a of the rotating shaft 2 is arranged. The process gas G that leaks only by the two seal portions 512 can be sealed by the first seal portion 511 to reduce the amount of leakage as the sealing device 51. Thus, a sealing effect can be obtained while suppressing unstable vibration of the rotating shaft 2.

  Further, since the second seal portion 512 is disposed on the high-pressure side of the first seal portion 511 in the axis P direction, the process gas G is introduced before the gap S1 between the first inner peripheral surface 511a and the outer peripheral surface 2a. It can be made to flow into the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a. By flowing the process gas G through the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a, stronger anisotropy can be generated. As a result, the unstable vibration generated in the rotating shaft 2 can be more effectively suppressed by intentionally swinging the rotating shaft 2 into an elliptical shape and stably maintaining this swinging.

  Further, by changing the radial distance between the second inner peripheral surface 512a and the outer peripheral surface 2a of the rotating shaft 2 in the circumferential direction, the size of the gap S2 between the second inner peripheral surface 512a and the outer peripheral surface 2a is increased. Will be different in direction. Therefore, the flow rate of the inflowing process gas G increases at both ends in the horizontal direction where the gap S2 is large, and the pressure acting on the rotating shaft 2 is reduced by the leakage flow. On the other hand, the flow rate of the inflowing process gas G decreases at the upper or lower end in the vertical direction where the gap S2 is small, and the pressure acting on the rotating shaft 2 increases due to the leakage flow. Accordingly, the pressure acting on the rotary shaft 2 is small at the circumferential horizontal position where the distance between the second inner peripheral surface 512a and the outer peripheral surface 2a is large, and the distance between the second inner peripheral surface 512a and the outer peripheral surface 2a is small. Anisotropy can be generated in the rigidity acting on the rotating shaft 2 by the leakage flow so that the pressure acting on the rotating shaft 2 becomes large at the circumferential vertical position. Accordingly, the second seal portion 512 having anisotropy can be easily formed.

  Further, the second inner peripheral surface 512a of the second seal structure is reduced in diameter in the direction of the axis P toward the first seal portion 511, and the first end edge 512b on the first seal side is formed on the first inner peripheral surface 511a. By being formed so as to coincide with each other, it is possible to smoothly connect without causing a large step at the joint between the second seal portion 512 and the first seal portion 511. Therefore, the second inner peripheral surface 512a and the outer periphery When the process gas G flowing through the gap S2 of the surface 2a flows into the gap S1 between the first inner peripheral surface 511a and the outer peripheral surface 2a, it is possible to reduce a loss caused by a step or the like.

  Furthermore, by providing the second seal portion 512 not only on the high pressure side but also on the low pressure side, anisotropy can be more effectively generated by the force acting on the rotating shaft 2 due to the leakage flow.

  Moreover, according to the rotary machine 1 using such a sealing device 51, the unstable vibration of the rotary shaft 2 can be suppressed, and the efficiency of the rotary machine 1 can be improved and the performance can be improved by reducing leakage. Can do.

<< Second Embodiment >>
Next, the sealing device 52 of the second embodiment will be described with reference to FIGS. 4 and 5.
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The sealing device 52 of the second embodiment is different from the first embodiment in the configuration of the second seal portion 522.

  That is, the second seal portion 522 of the second embodiment has a fin portion 523 extending from the second inner peripheral surface 522a having a shape different from that of the first embodiment toward the outer peripheral surface 2a of the rotating shaft 2. The second inner peripheral surface 522a of the second embodiment has a constant distance that the radial distance from the outer peripheral surface 2a is wider than the radial distance between the first inner peripheral surface 511a and the outer peripheral surface 2a over the entire circumference. Is formed. Specifically, the second inner peripheral surface 522a of the present embodiment has a perfect circle shape in which the first end edge 522b and the second end edge 522c are larger in diameter than the end edge of the first inner peripheral surface 511a. .

  As shown in FIGS. 4 and 5, a plurality of fin portions 523 are arranged in the circumferential direction of the rotating shaft 2 on the second inner peripheral surface 522a. The fin portion 523 extends in a flat plate shape from the second inner peripheral surface 522a toward the axis P. The fin part 523 is provided so that the space | interval of the fin parts 523 adjacent to the circumferential direction may be changed in the circumferential direction. That is, if the positions in the circumferential direction are different, the intervals between adjacent fin portions 523 are different. Specifically, the fin portions 523 of the present embodiment are arranged such that the distance between the phone portions is the smallest at the upper or lower end in the vertical direction. And as for the fin part 523, the space | interval of fin parts 523 spreads toward the both ends of a horizontal direction, and a space | interval becomes the largest in the position of the both ends of the horizontal direction which differs 90 degrees in the circumferential direction from this position of an upper end or a lower end. It is arranged as follows. That is, in the second seal portion 522, the fin portions 523 are most densely arranged at the upper and lower ends in the vertical direction, and the fin portions 523 are sparsely arranged at both ends in the horizontal direction.

  According to the sealing device 52 as described above, the number of the fin portions 523 arranged in the circumferential direction is different by changing the interval between the fin portions 523 adjacent in the circumferential direction in the circumferential direction. Of the leakage flow, the leakage swirl flow collides with the fin portion 523, thereby reducing the leakage swirl flow velocity. However, at both ends in the horizontal direction, where the fin portions 523 are sparsely arranged, there are few fin portions 523 that block the leakage swirl flow, so the effect of reducing the leakage swirl flow velocity is low. On the other hand, at the upper and lower ends in the vertical direction, where the fin portions 523 are densely arranged, there are many fin portions 523 that block the leakage swirl flow, so that the effect of reducing the leakage swirl flow velocity is increased. That is, the leakage swirl flow velocity in the vicinity of the outer peripheral surface 2a of the rotating shaft 2 is small at the circumferential position where the fin portions 523 are few, and the outer peripheral surface 2a of the rotating shaft 2 is located at the circumferential position where the fin portions 523 are many. Nearby leakage swirl flow velocity increases. Accordingly, anisotropy can be generated in the rigidity acting on the rotary shaft 2 due to the leakage swirl flow. Therefore, the second seal part 522 having anisotropy can be easily formed.

<< Third embodiment >>
Next, the sealing device 53 of the third embodiment will be described with reference to FIGS.
In 3rd embodiment, the same code | symbol is attached | subjected to the component similar to 1st embodiment and 2nd embodiment, and detailed description is abbreviate | omitted. The sealing device 53 of the third embodiment is different from the first embodiment and the second embodiment in the configuration of the second seal portion 532.

  That is, the second seal portion 532 of the third embodiment changes the length in the axis P direction in the circumferential direction of the rotating shaft 2. In other words, the second seal portion 532 has a different length in the axis P direction when the circumferential position is different. The second seal portion 532 is formed such that the shape of the second inner peripheral surface 532a viewed from the direction of the axis P is the same shape as the first seal portion 511. That is, as shown in FIG. 6, the second inner peripheral surface 532a has a perfect circle shape in which the first end edge 532b and the second end edge 532c have the same diameter as the end edge of the first inner peripheral surface 511a.

  The length of the second seal portion 532 in the axis P direction from the first seal portion 511 side toward the high pressure side or the low pressure side changes in the circumferential direction. Specifically, as shown in FIGS. 7A and 7B, the second seal portion 532 is longer in the direction of the axis P at the positions of both ends in the horizontal direction than at the positions of the upper end or the lower end in the vertical direction. Is formed.

  Further, as shown in FIG. 8, for example, the second seal portion 532 arranged on the high pressure side has an end surface facing the high pressure side facing from the position of both ends in the horizontal direction to the position of the upper end and the lower end in the vertical direction in the circumferential direction. Connected gently. That is, the second seal portion 532 disposed on the high pressure side is formed such that an end surface facing the first seal side in the axis P direction is flat and an end surface facing the high pressure side in the axis P direction is wavy. In addition, the 2nd seal part 532 arrange | positioned at the low voltage | pressure side is formed so that the end surface which faces a low voltage | pressure side may wave, contrary to the 2nd seal part 532 arrange | positioned at the high voltage | pressure side.

  According to the sealing device 53 as described above, the length of the axis P direction changes in the circumferential direction, so that the process gas G flowing in the gap S2 between the second inner peripheral surface 532a and the outer peripheral surface 2a Energy loss will vary in the circumferential direction. Among the leakage flows, the leakage axial flow causes energy loss due to friction by flowing in the gap P2 between the second inner peripheral surface 532a and the outer peripheral surface 2a in the axis P direction. Therefore, energy loss increases at both ends in the horizontal direction where the length in the axis P direction is long. On the other hand, energy loss is small at the upper and lower ends in the vertical direction where the length in the axis P direction is short. Therefore, anisotropy can be generated in the rigidity acting on the rotating shaft 2 due to the leakage axial flow. Therefore, the second seal portion 532 having anisotropy can be easily formed.

<< 4th embodiment >>
Next, the sealing device 54 according to the fourth embodiment will be described with reference to FIGS. 9 to 11.
In the fourth embodiment, the same components as those in the first embodiment to the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The sealing device 54 according to the fourth embodiment is different from the first embodiment in the configuration of the second seal portion 542 from the first embodiment.

  That is, the second seal portion 542 of the fourth embodiment changes the surface roughness of the surface facing the outer peripheral surface 2 a in the circumferential direction of the rotary shaft 2. In other words, the second seal portion 542 has a different surface roughness when the circumferential position is different. The second seal portion 542 is formed so that the shape of the second inner peripheral surface 542a viewed from the direction of the axis P is the same as that of the third embodiment. That is, as shown in FIG. 9, the second inner peripheral surface 542a has a first end edge 542b and a second end edge 542c in a perfect circle shape with the same diameter as the end edge on the first inner peripheral surface 511a.

Further, as shown in FIG. 10, the second seal portion 542 is formed to have the same length in the axis P direction over the entire circumference.
Then, as shown in FIG. 11, the second seal portion 542 gradually becomes rougher as the surface roughness of the second inner peripheral surface 542a goes from the position of the upper end or the lower end in the vertical direction to the position of both ends in the horizontal direction. It is formed as follows. That is, the second inner peripheral surface 542a is formed so that the unevenness of the surface is the smallest at the positions of the upper and lower ends in the vertical direction, and is formed so that the unevenness of the surface is the largest at the positions of both ends in the horizontal direction. Yes. For example, the second inner peripheral surface 542a of the present embodiment is formed rough so that polishing is not performed after machining at both ends in the horizontal direction, and polishing is performed at the positions of the upper and lower ends in the vertical direction. Is formed smoothly like a mirror surface.

  According to the sealing device 54 as described above, the surface roughness of the second inner peripheral surface 542a changes in the circumferential direction, and thus flows through the gap S2 between the second inner peripheral surface 542a and the outer peripheral surface 2a. The energy loss of the process gas G differs in the circumferential direction. Therefore, energy loss increases at both ends in the horizontal direction where the surface roughness is rough. On the other hand, energy loss is small at the upper and lower ends in the vertical direction with fine surface roughness. Therefore, anisotropy can be generated in the rigidity acting on the rotating shaft 2 due to the leakage axial flow. Therefore, the second seal part 542 having anisotropy can be easily formed.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

  In addition, each embodiment mentioned above may be used as an independent structure, respectively, and may be used in combination. For example, the second seal portion 512 of the first embodiment and the second seal portion 522 of the second embodiment are combined, and the fin portion 523 is provided while the shape of the second inner peripheral surface 512a changes in the circumferential direction. It may be. That is, the constituent elements in each embodiment may be appropriately combined by replacing the constituent elements in the other embodiments.

  Further, the second seal portions 512, 522, 532, and 542 are not limited to being disposed on both sides in the axis P direction of the first seal portion 511 as in the present embodiment. That is, the second seal portions 512, 522, 532, and 542 may be provided, for example, only on the high pressure side in the axis P direction of the first seal portion 511, or conversely, may be provided only on the low pressure side.

  Furthermore, when the bearing 3 is formed so as to have anisotropic rigidity with respect to the rotating shaft 2, the second seal portions 512, 522, 532, and 542 are anisotropic in the same direction as the bearing 3. Further, it is preferable to match the circumferential position for changing the structure with the bearing 3.

Moreover, in each embodiment mentioned above, although the sealing apparatus 51, 52, 53, 54 demonstrated the case where it provided around the rotating shaft 2 between the three-stage impeller group 4B and the three-stage impeller group 4A. It is not limited to this. For example, you may provide in the nozzle | cap | die part of the inlet_port | entrance of the impeller 4, and the balance piston part provided in the last stage of a multistage impeller.
Further, the impeller 4 is not limited to a closed type impeller, and may be an open type impeller.

  Further, the impeller 4 is not limited to a three-stage type. Moreover, in each embodiment mentioned above, the centrifugal compressor was demonstrated to the example as the rotary machine 1 which provides the sealing devices 51, 52, 53, and 54. However, the rotary machine 1 is not limited to a centrifugal compressor. The sealing devices 51, 52, 53, and 54 of the present invention can be applied to, for example, an axial flow compressor, a radial flow turbine, an axial flow turbine, various industrial compressors, a turbo refrigerator, and the like.

DESCRIPTION OF SYMBOLS 1 ... Rotating machine P ... Axis C ... Center position G ... Process gas 2 ... Rotating shaft 2a ... Outer peripheral surface 3 ... Bearing 4 ... Impeller 4A, 4B ... Three-stage type impeller group 4a ... Disk 4b ... Cover 4c ... Blade 51, 52 53, 54 ... Sealing device 511 ... First seal part 511a ... First inner peripheral surface 512, 522, 532, 542 ... Second seal part 512a, 522a, 532a, 542a ... Second inner peripheral surface 512b, 522b, 532b , 542b ... first end edge 512c, 522c, 532c, 542c ... second end edge S ... gap L ... equal distance 6 ... casing 6aA ... casing channel 6bA ... suction port 6cA ... suction channel 6dA ... discharge channel 6eA ... Discharge port 6aB ... Casing channel 6bB ... Suction port 6cB ... Suction channel 6dB ... Drain channel 6eB ... Drain port 523 ... Fin part

Claims (5)

A sealing device that seals the flow of fluid in the direction along the axis of the rotary shaft on the outer peripheral surface of the rotary shaft over the entire circumference of the outer peripheral surface of the rotary shaft,
A first seal portion facing the outer peripheral surface of the rotating shaft and uniformly formed in the circumferential direction of the rotating shaft;
A second seal portion that faces the outer peripheral surface of the rotating shaft and is formed to change the structure in the circumferential direction of the rotating shaft;
Said second sealing portion, at least one et provided on the side of the axial direction of the first sealing portion is,
The second seal portion is arranged in a plurality in the circumferential direction of the rotating shaft, and has a fin portion extending toward the outer peripheral surface of the rotating shaft,
The said fin part is a sealing device provided so that the space | interval of the said fin parts adjacent to the circumferential direction of the said rotating shaft may be changed in the circumferential direction of the said rotating shaft .   The sealing device according to claim 1, wherein the second seal portion is provided on a high pressure side of the first seal portion.   The sealing device according to claim 1, wherein the second seal portion is formed so as to change a distance from an outer peripheral surface of the rotating shaft in a circumferential direction of the rotating shaft. 4. The seal device according to claim 1, wherein the second seal portion changes a length in the axial direction in a circumferential direction of the rotation shaft. 5. A rotary machine comprising the sealing device according to any one of claims 1 to 4 .

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