JP6233640B2 - 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 types of seals.

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.

  In Patent Document 1, a seal device is provided in which a damper seal is disposed on the high-pressure side of the rotating machine in the axial direction of the rotating shaft, and an annular seal formed with a smooth surface facing the outer peripheral surface of the rotating shaft is disposed on the low-pressure side. Is disclosed. By using such a sealing device, the damping frequency is effectively exerted by the damper seal, and the natural frequency is increased by the rigidity effect of the fluid between the seal and the rotating shaft by increasing the length of the annular seal. Is suppressed, and the stability of the rotating shaft is improved.

JP 2013-160297 A

By the way, in the sealing device as described above, a part of the fluid compressed in the rotary machine flows into the gap between the rotating shaft and the sealing device while turning.
However, in the sealing device as described above, it is difficult to sufficiently reduce the influence caused by the swirling flow. In other words, when fluid flows into the gap between the seal device and the rotating shaft while swirling, the destabilizing force increases, increasing the unstable vibration of the rotating shaft, and increasing the amount of leakage from the seal. It is difficult to reduce that.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a sealing device that can reduce the influence of leakage flow, and a rotary machine including the same.

In order to solve the above problems, the present invention proposes the following means.
A sealing device according to an aspect of the present invention is a sealing device that seals a fluid flow in a direction along the axis of the rotary shaft on the outer peripheral surface of the rotary shaft, and covers the outer peripheral surface of the rotary shaft. An annular main body having a plurality of holes formed so as to be opposed to the outer peripheral surface of the rotating shaft is formed on an inner peripheral surface to be disposed, and at least a part of the plurality of holes is a central axis of the hole As the direction of is directed from the opening of the hole toward the bottom, it is inclined toward at least one of the front side in the rotational direction of the rotary shaft and the downstream side of the fluid flow along the axial direction of the rotary shaft , The plurality of holes are arranged side by side in the circumferential direction of the inner circumferential surface on the inner circumferential surface, and move from a horizontal position of the inner circumferential surface to a vertical position that is 90 degrees different in the circumferential direction. The front side in the rotation direction of the rotation axis of the central axis of the hole Angle inclined toward is gradually larger.

  According to such a sealing device, the fluid flowing out from the hole into the gap can be caused to collide with the component facing the flow of the fluid flowing through the gap between the inner peripheral surface of the main body and the rotation shaft, It is possible to reduce the momentum of the flow of fluid flowing through the. Therefore, the destabilizing force due to the swirling flow around the outer peripheral surface of the rotating shaft can be reduced, and the unstable vibration of the rotating shaft can be reduced. Furthermore, the amount of fluid leaking toward the downstream side through the gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the main body can be reduced. That is, it is possible to reduce the influence of the leakage flow in the gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the main body.

  According to such a sealing device, the turning flow velocity at the position on one side of the inner peripheral surface of the main body can be further reduced as compared with the turning flow velocity at the other side position that is 90 degrees different in the circumferential direction. Therefore, the swirling flow velocity has anisotropy in the circumferential direction of the seal, and the rigidity effect and the damping effect due to the fluid between the inner peripheral surface affected by the swirling flow velocity and the rotating shaft are also anisotropic in the two orthogonal directions of the circumferential direction. have. This anisotropy of the seal characteristic works to weaken the round motion around the axis when the shaft is unstable, so that unstable vibration of the rotating shaft can be reduced.

  Moreover, the rotary machine in 1 aspect of this invention is equipped with the said sealing apparatus.

  According to such a rotary machine, the effect of suppressing the unstable vibration of the rotary shaft is high, and the efficiency as a rotary machine can be improved by reducing the leakage flow rate, thereby improving the performance.

  According to the sealing device of the present invention, the influence of the leakage flow can be reduced by forming a plurality of holes by inclining the main body.

It is sectional drawing which shows the rotary machine in 1st embodiment of this invention. It is a perspective view which shows the sealing device in 1st embodiment of this invention. FIG. 3 is a cross-sectional view corresponding to AA in FIG. 2 illustrating the sealing device and the rotation shaft in the first embodiment of the present invention. FIG. 3 is a cross-sectional view corresponding to BB in FIG. 2 showing the sealing device and the rotation shaft in the first embodiment of the present invention. It is a principal part expanded sectional view which shows the sealing device and rotating shaft in 1st embodiment of this invention. It is AA corresponding sectional drawing of FIG. 2 which shows the sealing device and rotating shaft in 2nd embodiment of this invention. It is a BB corresponding sectional view of Drawing 2 showing a sealing device and a rotating shaft in a second embodiment of the present invention. It is a principal part expanded sectional view which shows the sealing device and rotating shaft in 2nd embodiment of this invention. It is AA corresponding sectional drawing of FIG. 2 which shows the sealing device and rotating shaft in 3rd embodiment of this invention. It is a BB corresponding sectional view of Drawing 2 showing a sealing device and a rotating shaft in a third embodiment of the present invention. It is AA corresponding sectional drawing of FIG. 2 which shows the sealing device and rotating shaft in 4th embodiment of this invention. It is BB corresponding sectional drawing of FIG. 2 which shows the sealing device and rotating shaft in 4th embodiment of this invention.

<< first embodiment >>
Hereinafter, a rotary machine 1 including a sealing device 5 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.
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 seal device 5 that is disposed between the impellers 4 and is provided along the outer peripheral surface 2a of the rotary 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. The impeller 4 is a so-called closed impeller 4 including 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 5 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 4B has a higher pressure than the three-stage impeller group 4A. Further, in the vicinity of the center position C, a gap S is formed between the outer peripheral surface 2 a of the rotary shaft 2 and the inner peripheral surface of the casing 6. Therefore, the process gas G is disposed on one side in the axis P direction in which the three-stage impeller group 4A is disposed, with the other side in the axis P direction in which the three-stage impeller group 4B is disposed through the gap S as an upstream side. It tends to flow toward the downstream side.
In view of this, the sealing device 5 in this embodiment is located near the central position C in order to suppress the flow of the process gas G from the upstream three-stage impeller group 4B to the downstream three-stage impeller group 4A. Is provided.

  The sealing device 5 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. The sealing device 5 has a main body 5a shown in FIG. 2 disposed so as to cover the outer peripheral surface 2a of the rotating shaft 2.

  As shown in FIGS. 3 and 4, the main body 5 a is an annular member that is disposed opposite to the outer peripheral surface 2 a of the rotating shaft 2 with a predetermined gap S for rotating the rotating shaft 2. . In the main body 5 a, a plurality of holes are formed in an inner peripheral surface 5 c that is a surface facing the outer peripheral surface 2 a of the rotating shaft 2 so as to face the outer peripheral surface 2 a of the rotating shaft 2. The main body 5a of the present embodiment has a plurality of first inclined holes 5b (holes) that are circular holes that are recessed radially outward from the inner peripheral surface 5c. That is, the main body 5a of the present embodiment is a hole pattern seal in which a plurality of first inclined holes 5b are arranged adjacent to each other in the circumferential direction and the axis P direction with respect to the inner peripheral surface 5c of the main body 5a. .

  The first inclined hole 5b is formed to be recessed from the inner peripheral surface 5c of the main body 5a so that a cross-sectional shape orthogonal to the central axis O1 forms a circular shape. The first inclined hole 5b is inclined toward the front side in the rotational direction R of the rotary shaft 2 as the direction of the central axis O1 of the first inclined hole 5b is directed from the opening of the first inclined hole 5b toward the bottom. . The rotation direction R of the rotating shaft 2 in this embodiment is a clockwise direction on the paper surface in FIG. Specifically, as shown in FIG. 5, the first inclined hole 5b passes through the intersection between the central axis O1 and the inner peripheral surface 5c of the main body 5a before forming the first inclined hole 5b. The central axis O1 is inclined with respect to the orthogonal axis Oa orthogonal to the rotation axis 2 so as to be a predetermined angle α in the circumferential direction of the rotation axis 2. In the present embodiment, it is preferable that the predetermined angle α is formed to be 10 degrees to 40 degrees. This is because the larger the angle α at which the first inclined hole 5b is inclined, the larger the opening in the inner peripheral surface 5c of the main body portion 5a, thereby reducing the number of first inclined holes 5b that can be arranged. And the point that machining by drilling or the like becomes more difficult as it is inclined.

Next, the operation of the sealing device 5 configured as described above will be described.
In the rotary machine 1 as described above, by compressing the process gas G that is a fluid, the process gas G is also added to the gap S between the outer peripheral surface 2a of the rotary shaft 2 and the inner peripheral surface 5c of the main body 5a. The portion flows in, and a leakage flow is generated in the direction of the axis P in a spiral shape around the outer peripheral surface 2a of the rotary shaft 2. This leakage flow is constituted by a leakage swirl flow that is a portion in the circumferential direction toward the rotation direction R of the rotary shaft 2 and a leak axial flow that is a component that is directed in the direction of the axis P of the rotation shaft 2. In the rotary machine 1 according to the present embodiment, the process gas G causing this leakage flow flows into the plurality of first inclined holes 5b formed in the main body 5a, whereby the axis of the rotary shaft 2 is obtained. The process gas G is prevented from flowing out from the upstream side toward the downstream side along the P direction.

  According to the sealing device 5 as described above, the rotational axis R in the rotational direction R of the rotary shaft 2 is set such that the central axis O1 of the first inclined hole 5b formed in the main body 5a is at a predetermined angle α with respect to the orthogonal axis Oa. By being inclined toward the front side, the size of the opening of the first inclined hole 5b in the inner peripheral surface 5c of the main body 5a matches the orthogonal axis Oa without the central axis O1 being inclined. It becomes larger than the opening of the hole when it is. Therefore, more process gas G can flow into the first inclined hole 5b. Therefore, the leakage amount of the process gas G flowing out toward the other side in the axis P direction which is the downstream side through the gap S between the outer peripheral surface 2a of the rotating shaft 2 and the inner peripheral surface 5c of the main body 5a is reduced. can do.

  Further, since the first inclined hole 5b is formed to be inclined toward the front side in the rotation direction R of the rotary shaft 2, the process gas G flowing into the first inclined hole 5b is formed at the bottom of the first inclined hole 5b. When colliding again and flowing out from the opening of the first inclined hole 5b into the gap S, as shown in FIG. 5, the component X1 heading to the axis P perpendicular to the outer peripheral surface 2a of the rotating shaft 2 is opposed to the leakage swirl flow. It can be made to flow out toward the gap S in a state having a component X2 opposite to the rotation direction R of the rotating shaft 2 to be rotated. Therefore, a flow having a component opposed to the leakage swirl flow can collide with the leakage swirl flow of the process gas G flowing through the gap S, and the leakage swirl flow velocity can be reduced. Therefore, the destabilizing force due to the leakage swirl flow of the gap S around the outer peripheral surface 2a of the rotating shaft 2 can be reduced, and the unstable vibration of the rotating shaft 2 can be reduced. That is, the influence of the leakage flow in the gap S between the outer peripheral surface 2a of the rotating shaft 2 and the inner peripheral surface 5c of the main body 5a can be reduced.

  Furthermore, according to the rotary machine 1 using such a sealing device 5, the unstable vibration of the rotary shaft 2 can be suppressed, and the efficiency of the rotary machine 1 can be improved by reducing leakage to improve performance. Can do.

<< Second Embodiment >>
Next, the sealing device 51 of the second embodiment will be described with reference to FIGS.
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 51 of the second embodiment is different from the first embodiment in the direction in which the hole is inclined.

  That is, in the sealing device 51 of the second embodiment, a second inclined hole 51b (hole) that is inclined in the axis P direction is formed in the main body 51a.

  Similarly to the first inclined hole 5b of the first embodiment, the second inclined hole 51b is formed to be recessed from the inner peripheral surface 51c of the main body 51a so that the cross-sectional shape orthogonal to the central axis O2 is circular. Yes. As shown in FIGS. 6 and 7, the second inclined hole 51b has a direction of the axis P of the rotary shaft 2 as the direction of the central axis O2 of the second inclined hole 51b moves from the opening of the second inclined hole 51b to the bottom. Is inclined toward one side in the direction of the axis P, which is the downstream side of the flow of the process gas G flowing through the gap S. Specifically, as shown in FIG. 8, the second inclined hole 51b is inclined so that the angle of the central axis O2 with respect to the orthogonal axis Oa becomes a predetermined angle α toward the axis P direction of the rotating shaft 2. Is formed. In the present embodiment, it is preferable that the predetermined angle α is formed to be 10 degrees to 40 degrees.

  According to the sealing device 51 as described above, the central axis O2 of the second inclined hole 51b formed in the main body 51a is in the direction of the axis P of the rotary shaft 2 so as to be a predetermined angle α with respect to the orthogonal axis Oa. Accordingly, the size of the opening of the second inclined hole 51b in the inner peripheral surface 51c of the main body 51a is not inclined so that the central axis O2 is not inclined. Is larger than the opening of the hole when it coincides with the orthogonal axis Oa. Therefore, more process gas G can flow into the second inclined hole 51b. Therefore, the leakage amount of the process gas G flowing out toward the other side in the axis P direction on the downstream side through the gap S between the outer peripheral surface 2a of the rotating shaft 2 and the inner peripheral surface 51c of the main body 51a is reduced. can do.

  Further, since the second inclined hole 51b is formed to be inclined toward the downstream side of the flow of the process gas G along the axis P direction of the rotation shaft 2, the process gas G flowing into the second inclined hole 51b is formed. When it collides with the bottom of the second inclined hole 51b and again flows out of the opening of the second inclined hole 51b into the gap S, as shown in FIG. 8, the component toward the axis P orthogonal to the outer peripheral surface 2a of the rotating shaft 2 It can be made to flow out toward the gap S in a state having X1 and a component X3 toward the upstream side facing the leakage axial flow. Therefore, the flow having the component opposite to the leakage axial flow can collide with the leakage axial flow of the process gas G flowing through the gap S, and the leakage axial flow velocity can be reduced. Therefore, the flow rate of the process gas G flowing through the gap S can be reduced, and the leakage amount of the process gas G flowing out through the gap S toward the other side in the axis P direction which is the downstream side can be further reduced. . That is, the influence of the leakage flow in the gap S between the outer peripheral surface 2a of the rotating shaft 2 and the inner peripheral surface 51c of the main body 51a can be reduced.

<< Third embodiment >>
Next, the sealing device 52 of the third embodiment will be described with reference to FIGS. 9 and 10.
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 52 of the third embodiment is different from the first embodiment and the second embodiment in the direction in which the hole is inclined.

  That is, the sealing device 52 of the third embodiment is inclined toward the front side in the rotation direction R of the rotary shaft 2 on the main body 52 a and the flow of the process gas G along the axis P direction of the rotary shaft 2. A third inclined hole 52b (hole) that is inclined toward the downstream side is formed.

  Similar to the first and second embodiments, the third inclined hole 52b is formed to be recessed from the inner peripheral surface 52c of the main body 52a so that the cross-sectional shape perpendicular to the central axis O3 is circular. . As shown in FIGS. 9 and 10, the third inclined hole 52b has a rotational direction R of the rotary shaft 2 as the direction of the central axis O3 of the third inclined hole 52b moves from the opening of the third inclined hole 52b to the bottom. While being inclined toward the front side of the rotary shaft 2, it is inclined toward one side of the axis P direction along the axis P direction of the rotary shaft 2. That is, the third inclined hole 52b has a shape combined with the first inclined hole 5b of the first embodiment and the second inclined hole 51b of the second embodiment. Specifically, the third inclined hole 52b is formed to be inclined such that the angle of the central axis O3 with respect to the orthogonal axis Oa is a predetermined angle α with respect to the circumferential direction of the rotating shaft 2 and the axis P direction. ing. In the present embodiment, it is preferable that the predetermined angles α are formed to be the same angle in the range of 10 degrees to 40 degrees.

  According to the sealing device 52 as described above, the third inclined hole 52b is formed to be inclined toward the front side in the rotation direction R of the rotation shaft 2 and the downstream side in the direction of the axis P of the rotation shaft 2. When the process gas G that has flowed into the third inclined hole 52b flows out into the gap S, not only the component X2 that opposes the leakage swirl flow but also the component X3 that opposes the leakage axial flow toward the gap S. Can be drained. Therefore, it is possible to collide a flow having a component facing each other with respect to the leakage swirl flow and the leakage axial flow of the process gas G flowing through the gap S, and the leakage flow includes both the leakage swirl flow and the leakage axial flow. The momentum can be reduced. Therefore, the amount of leakage of the process gas G can be further reduced while reducing the destabilizing force due to the leakage flow around the outer peripheral surface 2a of the rotating shaft 2 and reducing the unstable vibration of the rotating shaft 2. That is, the influence of the leakage flow in the gap S between the outer peripheral surface 2a of the rotating shaft 2 and the inner peripheral surface 52c of the main body 52a can be further reduced.

<< 4th embodiment >>
Next, the sealing device 53 of the fourth embodiment will be described with reference to FIGS. 11 and 12.
In the fourth 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 53 of the fourth embodiment is different from the first embodiment in that the angle at which the hole is inclined differs in the circumferential direction.

  That is, in the sealing device 53 of the fourth embodiment, a fourth inclined hole 53b (hole) in which the angle inclined toward the front side in the rotation direction R of the rotating shaft 2 is different in the circumferential direction is formed in the main body 53a. ing.

  The fourth inclined hole 53b is formed to be recessed from the inner peripheral surface 53c of the main body 53a so that the cross-sectional shape orthogonal to the central axis O4 is circular. The fourth inclined hole 53b is formed such that the direction of the central axis O4 of the fourth inclined hole 53b moves from the opening of the fourth inclined hole 53b toward the bottom depending on the position formed in the circumferential direction of the axis P on the inner peripheral surface 53c. The angle of inclination of the rotary shaft 2 toward the front side in the rotation direction R is changed. Specifically, the fourth inclined holes 53b are arranged side by side in the circumferential direction of the inner circumferential surface 53c on the inner circumferential surface 53c, and 90 ° in the circumferential direction from the position in the horizontal direction D2 that is one side of the inner circumferential surface 53c. The angle which inclines toward the front side of the rotation direction R of the rotating shaft 2 of the center axis | shaft O4 is formed gradually large as it goes to the position of the perpendicular direction D1 which is another side which is different. That is, the fourth inclined hole 53b has a vertical direction D1 which is the other direction rotated 90 degrees with respect to the horizontal direction D2 from the horizontal direction D2 which is one direction in the radial direction of the axis P of the rotary shaft 2 on the inner peripheral surface 53c. It is formed so that the inclination angle gradually increases as it goes to. More specifically, an opening is formed in the horizontal direction D2 on the inner peripheral surface 53c of the main body 53a so that the angle with respect to the orthogonal axis Oa of the central axis O4 formed by inclining in the circumferential direction of the rotating shaft 2 is formed. The fourth inclined hole 53b is formed at 10 degrees. And in the 4th inclination hole 53b by which opening was formed in the perpendicular direction D1 in the internal peripheral surface 53c of the main-body part 53a, it forms at 40 degree | times. Therefore, as shown in FIG. 11, the angle with respect to the orthogonal axis Oa of the central axis O4 is formed at 10 degrees on the right side in the horizontal direction D2, and on the upper side in the vertical direction D1 while gradually increasing the angle. The angle of the central axis O4 with respect to the orthogonal axis Oa is formed at 40 degrees. The angle gradually decreases toward the left side of the paper in the horizontal direction D2, and the angle of the central axis O4 with respect to the orthogonal axis Oa is formed at 10 degrees on the left side of the paper in the horizontal direction D2. Similarly, the angle gradually increases toward the lower side of the sheet, which is below the vertical direction D1, and gradually decreases toward the right side of the sheet in the horizontal direction D2.

  According to the sealing device 53 as described above, the fourth inclined hole 53b is formed so that the inclination angle gradually increases from the horizontal direction D2 toward the vertical direction D1, so that the fourth inclined hole 53b flows into the fourth inclined hole 53b. The magnitude of the component opposite to the rotation direction R of the rotating shaft 2 that faces the leakage swirl flow when the process gas G flows into the gap S can be changed by the position in the circumferential direction of the axis P. Specifically, the component facing the leakage swirl flow most in the fourth inclined hole 53b formed in the horizontal direction D2 is reduced, and the component facing the leakage swirl flow most in the fourth inclined hole 53b formed in the vertical direction D1. The component to do can be enlarged. Therefore, the leakage swirl flow velocity at the position in the vertical direction D1 can be greatly reduced compared to the leakage swirl flow velocity at the position in the horizontal direction D2. Therefore, the swirling flow velocity has anisotropy in the circumferential direction of the seal, and the rigidity effect and the damping effect due to the fluid between the inner peripheral surface 53c affected by the swirling flow velocity and the rotating shaft 2 are also different in the two orthogonal directions of the circumferential direction. Has a direction. The anisotropy of the sealing characteristics serves to weaken the round motion around the axis P during unstable vibration of the rotating shaft 2, so that unstable vibration of the rotating shaft 2 can be reduced.

  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 the present embodiment, the holes formed in the main body portions 5a, 51a, 52a, and 53a are circular. However, the present invention is not limited to this, and may be hexagonal or square, for example.
Further, as the sealing devices 5, 51, 52, 53, the holes are limited to be formed adjacent to each other in the circumferential direction and the axis P direction on the inner peripheral surface 53c of the main body portions 5a, 51a, 52a, 53a. Instead, it may be formed with a certain interval.

Furthermore, in each embodiment mentioned above, although the sealing apparatus 5, 51, 52, 53 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 5, 51, 52, and 53. However, the rotary machine 1 is not limited to a centrifugal compressor. The sealing devices 5, 51, 52, 53 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 impeller group 4a ... Disk 4b ... Cover 4c ... Blade 5, 51 52a, 53 ... sealing device 5a, 51a, 52a, 53a ... main body 5b ... first inclined hole O1, O2, O3, O4 ... central axis Oa ... orthogonal axis S ... gap 6 ... casing 6aA, 6aB ... casing flow path 6bA, 6bB ... suction port 6cA, 6cB ... suction channel 6dA, 6dB ... discharge channel 6eA, 6eB ... discharge port 51b ... second inclined hole 52b ... third inclined hole 53b ... fourth inclined hole D1 ... vertical direction D2 ... horizontal direction

Claims (2)

A sealing device that seals a fluid flow in a direction along the axis of the rotating shaft on the outer peripheral surface of the rotating shaft,
An annular main body having a plurality of holes formed on an inner peripheral surface disposed to cover the outer peripheral surface of the rotary shaft so as to face the outer peripheral surface of the rotary shaft;
At least some of the plurality of holes are configured such that the direction of the center axis of the holes is directed to the front side in the rotation direction of the rotation shaft and the axial direction of the rotation shaft as the direction from the opening of the hole toward the bottom. Inclined toward at least one side of the downstream side of the flow ,
The plurality of holes are arranged side by side in the circumferential direction of the inner circumferential surface on the inner circumferential surface, and move from a horizontal position of the inner circumferential surface to a vertical position that is 90 degrees different in the circumferential direction. A sealing device in which an angle of inclination of the central axis of the hole toward the front side in the rotational direction of the rotary shaft is gradually increased . A rotary machine comprising the sealing device according to claim 1 .

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