JP7350521B2 - rotating machinery - Google Patents

Description

The present invention relates to rotating machines.

For example, rotating machines such as centrifugal compressors, centrifugal pumps, generators, and turbines include a rotor as a rotating body that rotates around an axis, and a casing as a stationary body that covers the rotor from the outside. Frictional resistance (disk friction loss) occurs between the rotating rotor and the stationary casing via the working fluid. In particular, in the case of a centrifugal compressor, it is known that in order to obtain a high head with respect to the discharge flow rate, the outer diameter of the impeller increases, which increases the disk friction loss described above.

As a technique for reducing such disk friction loss, the technique described in Patent Document 1 below is known. In Patent Document 1, a space on the back side is divided into a plurality of spaces by providing a plurality of fences at intervals in the radial direction on the back side of an impeller of a centrifugal compressor. It is said that this allows the velocity distribution within each space to be controlled and disc friction loss to be reduced.

Japanese Patent Application Publication No. 3-11198

However, in the device described in Patent Document 1, the fluid flowing in the divided space is in contact with the inner surface of the casing, which is a stationary body. Therefore, friction loss exists between the impeller back surface and the casing. That is, the device described in Patent Document 1 still has room for improvement. Further, since the outer circumferential surface of the impeller has a higher circumferential speed than other parts, the friction loss occurring between the outer circumferential surface and the casing cannot be ignored.

The present invention was made to solve the above problems, and an object of the present invention is to provide a rotating machine with improved efficiency by further reducing friction loss.

A rotating machine according to one aspect of the present invention includes a rotating body that is rotatable around an axis and has a first opposing surface extending in a plane intersecting the axis, and a rotating body that is opposite to the first opposing surface from the axial direction. and a stationary body having a second opposing surface forming a flow path through which fluid flows between the stationary body and the first opposing surface, the first opposing surface having a second opposing surface extending in a direction perpendicular to the axis. one main surface, and a radially outer edge of the first main surface with respect to the axis , provided continuously in the circumferential direction on the radially outer edge, and receding from the first main surface in the axial direction. a retreating surface, the second opposing surface has a second main surface that faces the first main surface in the axial direction and extends in a direction perpendicular to the axis; and a second main surface that extends in the direction perpendicular to the axis; an inclined surface that is connected to the outside in the radial direction, is inclined with respect to the axis toward the retreating surface from the inside in the radial direction to the outside with respect to the axis, and extends outward in the radial direction from the retreating surface. However, the retreating surface and the inclined surface define a space that extends annularly about the axis.

In the above configuration, for example, when fluid flows from the inside in the radial direction to the outside in the flow path between the first opposing surface and the second opposing surface, the receding surface of the first opposing surface and the second opposing surface Some of the fluid is trapped in the space between the surface and the inclined surface. The trapped fluid forms a vortex within the space. Here, the fluid flowing through the flow path includes a circumferential velocity component accompanying the rotation of the rotating body. Therefore, the above-mentioned vortex is also in a rotating state while containing a circumferential velocity component. The presence of this vortex can reduce the friction loss that occurs between the rotating body and the stationary body.

In the rotating machine, the radially inner edge of the inclined surface may be located radially inner than the radially inner edge of the retreating surface in the axial direction.

According to the above configuration, when fluid flows from the inside in the radial direction to the outside in the flow path, for example, the fluid can be guided to the inclined surface starting from a position radially inside the retreating surface. That is, the fluid guided by the inclined surface can be quickly guided between the inclined surface and the retreating surface. Therefore, a vortex can be formed more stably between the inclined surface and the retreating surface.

The radially inner edge of the inclined surface may be located at the same position as the radially inner edge of the retreating surface in the axial direction.

According to the above configuration, the radially inner edge of the inclined surface and the radially inner edge of the retreating surface are at the same position in the radial direction. Thereby, the separation distance between the inclined surface and the retreating surface can be ensured. As a result, even if the rotating body is displaced in a direction approaching the stationary body, for example, the possibility that the rotating body and the stationary body will come into contact can be reduced.

In the rotating machine, the radially inner edge of the inclined surface may be located radially outer than the radially inner edge of the retreating surface in the axial direction.

According to the above configuration, the radially inner edge of the inclined surface is located radially outer than the radially inner edge of the retreating surface. Thereby, the separation distance between the inclined surface and the retreating surface can be ensured. As a result, even if the rotating body is displaced in a direction approaching the stationary body, for example, the possibility that the rotating body and the stationary body will come into contact can be reduced.

A rotating machine according to one aspect of the present invention includes a rotating body that is rotatable around an axis and has a first opposing surface extending in a plane intersecting the axis, and a rotating body that is opposite to the first opposing surface from the axial direction. and a stationary body having a second opposing surface forming a flow path through which fluid flows between the first opposing surface and the first opposing surface, the first opposing surface having a radially outer edge with respect to the axis. has a receding surface that is continuously provided in the circumferential direction and that is recessed in the axial direction from the first opposing surface, and the second opposing surface extends from the inside in the radial direction to the outside with respect to the axis. It has an inclined surface that is inclined with respect to the axis so as to face the retreating surface, and the inclined surface has a curved surface that is convex toward the side away from the retreating surface.

According to the above configuration, since the inclined surface has a curved shape, the fluid can be guided more smoothly along the inclined surface. Thereby, the vortex can be held more stably between the retreating surface and the inclined surface.

In the rotating machine, the inclined surface includes a recess that is recessed from the inclined surface in the axial direction and continuous in the circumferential direction at a position corresponding to the radially outer edge of the retreating surface in the radial direction with respect to the axis. Grooves may also be formed.

According to the above configuration, since the groove is formed on the inclined surface, even if the rotating body is displaced in a direction approaching the stationary body, for example, the rotating body and the stationary body can come into contact with each other. It is possible to reduce the

A rotating machine according to one aspect of the present invention includes a rotating body that is rotatable around an axis and has a first opposing surface extending in a plane intersecting the axis, and a rotating body that is opposite to the first opposing surface from the axial direction. and a stationary body having a second opposing surface forming a flow path through which fluid flows between the first opposing surface and the first opposing surface, the first opposing surface having a radially outer edge with respect to the axis. has a receding surface that is continuously provided in the circumferential direction and that is recessed in the axial direction from the first opposing surface, and the second opposing surface extends from the inside in the radial direction to the outside with respect to the axis. The rotating body has a plurality of receding surfaces arranged from the inner side to the outer side in the radial direction, and the rotating body has a plurality of receding surfaces arranged from the inner side to the outer side in the radial direction. The more the recessed surface is located on the outer side, the more recessed the recessed surface is from the first opposing surface in the axial direction.

According to the above configuration, since the plurality of retreating surfaces are formed, it is possible to form a plurality of vortices from the inside in the radial direction to the outside. As a result, a plurality of vortices are present between the inclined surface and the retreating surface. Each vortex contains a circumferential velocity component accompanying the rotation of the rotating body. Therefore, according to the above configuration, it is possible to further reduce the friction loss occurring between the rotating body and the stationary body.

According to the present invention, it is possible to provide a rotating machine with improved efficiency by further reducing friction loss.

1 is a sectional view showing the configuration of a centrifugal compressor as a rotating machine according to a first embodiment of the present invention. 1 is an enlarged sectional view showing the configuration around an impeller of a centrifugal compressor according to a first embodiment of the present invention. FIG. 1 is an enlarged sectional view of a main part of a disk according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of a cover according to a first embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of essential parts showing a modification of the centrifugal compressor according to the first embodiment of the present invention. FIG. 7 is an enlarged sectional view of a main part showing a further modification of the centrifugal compressor according to the first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of a centrifugal compressor according to a second embodiment of the present invention. FIG. 3 is an enlarged sectional view of a main part of a centrifugal compressor according to a third embodiment of the present invention. FIG. 7 is an enlarged sectional view of a main part showing a modification of a centrifugal compressor according to a third embodiment of the present invention. (concave groove)

[First embodiment]
A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. In this embodiment, a multi-stage centrifugal compressor as a rotating machine will be described as an example. Note that the configuration of this embodiment can also be applied to a single-stage centrifugal compressor, centrifugal pump, generator, or turbine as a rotating machine.

The centrifugal compressor 100 includes a rotating shaft 1 that rotates around an axis, a casing 3 as a stationary body S that forms a fluid flow path 2 by covering the periphery of the rotating shaft 1, and a rotating shaft provided on the rotating shaft 1. A plurality of impellers 4 as a body R are provided.

The casing 3 has a cylindrical shape extending along the axis O. The rotating shaft 1 extends through the inside of the casing 3 along the axis O. A journal bearing 5 and a thrust bearing 6 are provided at both ends of the casing 3 in the direction of the axis O, respectively. The rotating shaft 1 is rotatably supported around an axis O by these journal bearings 5 and thrust bearings 6.

An intake port 7 for taking in air as the working fluid G from the outside is provided on one side of the casing 3 in the direction of the axis O. Furthermore, an exhaust port 8 is provided on the other side of the casing 3 in the direction of the axis O, through which the working fluid G compressed inside the casing 3 is exhausted.

Inside the casing 3, an internal space is formed which communicates the intake port 7 and the exhaust port 8 and whose diameter is repeatedly contracted and expanded. This internal space accommodates a plurality of impellers 4 and forms a part of the fluid flow path 2 described above. In the following description, the side on this fluid flow path 2 where the intake port 7 is located will be referred to as the upstream side, and the side where the exhaust port 8 will be located will be referred to as the downstream side.

A plurality of (six) impellers 4 are provided on the rotating shaft 1 at intervals in the direction of the axis O on the outer peripheral surface thereof. As shown in FIG. 2, each impeller 4 includes a disk 41 having a substantially circular cross section when viewed from the direction of the axis O, a plurality of blades 42 provided on the upstream surface of the disk 41, and a plurality of blades 42 provided on the upstream side of the disk 41. 42 from the upstream side.

The disk 41 is formed so that its radial dimension gradually increases from one side to the other side in the direction of the axis O, as viewed from a direction intersecting the axis O, so that the disk 41 has a generally conical shape. There is.

A plurality of blades 42 are arranged radially outward in the radial direction about the axis O on a conical surface facing upstream of both surfaces of the disk 41 in the direction of the axis O. More specifically, these blades are formed by thin plates that stand upright from the upstream surface of the disk 41 toward the upstream side. When viewed from the direction of the axis O, these plurality of blades 42 are curved from one side to the other side in the circumferential direction.

A cover 43 is provided on the upstream edge of the blade 42 . In other words, the plurality of blades 42 are held between the cover 43 and the disk 41 from the direction of the axis O. Thereby, a space is formed between the cover 43, the disk 41, and the pair of blades 42 adjacent to each other. This space forms a part of the fluid flow path 2 (compression flow path 22), which will be described later.

The fluid flow path 2 is a space that communicates the impeller 4 configured as described above with the internal space of the casing 3. In this embodiment, the explanation will be given assuming that one fluid flow path 2 is formed for each impeller 4 (for each compression stage). That is, in the centrifugal compressor 100, five fluid flow paths 2 that are continuous from the upstream side to the downstream side are formed corresponding to the five impellers 4 excluding the impeller 4 at the last stage.

Each fluid flow path 2 has a suction flow path 21, a compression flow path 22, a diffuser flow path 23, a return bend portion 24, and a guide flow path 25. Note that FIG. 2 shows only one stage of the impeller 4 among the fluid flow path 2 and the impeller 4.

In the first stage impeller 4, the suction flow path 21 is directly connected to the above-mentioned intake port 7. Through this suction channel 21, external air is taken into each channel on the fluid channel 2 as the working fluid G. More specifically, this suction flow path 21 gradually curves from the axis O direction toward the outside in the radial direction as it goes from the upstream side to the downstream side.

The suction flow path 21 in the impeller 4 of the second and subsequent stages is communicated with the downstream end of a guide flow path 25 (described later) in the fluid flow path 2 of the previous stage (first stage). That is, the working fluid G that has passed through the guide channel 25 has its flow direction changed so that it faces downstream along the axis O, similarly to the above.

The compression channel 22 is a channel surrounded by the upstream surface of the disk 41, the downstream surface of the cover 43, and a pair of circumferentially adjacent blades 42. More specifically, the compression flow path 22 has a cross-sectional area that gradually decreases from the inside to the outside in the radial direction. As a result, the working fluid G flowing through the compression channel 22 while the impeller 4 is rotating is gradually compressed and becomes a high-pressure fluid.

The diffuser flow path 23 is a flow path extending from the inside in the radial direction of the axis O toward the outside. A radially inner end of the diffuser flow path 23 is communicated with a radially outer end of the compression flow path 22 .

The return bend portion 24 reverses the flow direction of the working fluid G that has passed through the diffuser channel 23 from the radially inner side to the radially outer side toward the radially inner side. One end (upstream side) of the return bend portion 24 is communicated with the diffuser channel 23 , and the other end (downstream side) is communicated with the guide channel 25 . In the middle of the return bend portion 24, the outermost portion in the radial direction is a top portion.

The guide channel 25 extends radially inward from the downstream end of the return bend portion 24 . A radially outer end of the guide channel 25 communicates with the return bend portion 24 described above. The radially inner end of the guide channel 25 is communicated with the suction channel 21 in the downstream fluid channel 2, as described above.

In the centrifugal compressor 100 configured as described above, a gap is formed between the casing 3 and the impeller 4 in order to realize smooth rotation of the impeller 4. More specifically, a gap is formed between the disk back surface 41A (first opposing surface P1) facing the downstream side of the disk 41 and the casing back surface 3A (second opposing surface P2) facing the disk back surface 41A. has been done. This gap is defined as a flow path F1. In the flow path F1, as shown by arrow A in FIG. 2, high-pressure fluid leaking from the compression flow path 22 on the rear stage side flows from the inside in the radial direction to the outside.

Furthermore, there is a gap between the cover upstream surface 43B (first opposing surface P1') facing the upstream side of the cover 43 and the casing upstream surface 3B (second opposing surface P2') opposing the cover upstream surface 43B. It is formed. This gap is defined as a flow path F2. In the flow path F2, as shown by arrow B in FIG. 2, the high-pressure fluid flowing through the diffuser flow path 23 flows from the outside in the radial direction to the inside.

There is also a gap between the disk outer circumferential surface 41C of the disk 41 facing radially outward, the cover outer circumferential surface 43C of the cover 43 facing radially outward, and the casing inner circumferential surface 3D, which is the inner circumferential surface of the casing 3. is formed. This gap is defined as a flow path F3 (outer flow path). The flow path F3 communicates with the flow path F1 and the flow path F2.

Here, between the impeller 4 as the rotating body R and the casing 3 as the stationary body S, frictional resistance (disc friction loss) is generated through the fluid flowing through the above-mentioned flow path F1 and flow path F2. arise. In particular, in the case of the centrifugal compressor 100, it is known that as the lift height increases, the outer diameter of the impeller 4 increases, so the disk friction loss described above increases. In addition, since the circumferential velocity of the fluid is highest on the outer circumferential surface of the impeller 4 (the above-mentioned disk outer circumferential surface 41C and cover outer circumferential surface 43C), the friction loss occurring between these outer circumferential surfaces and the casing inner circumferential surface 3D is also need to be reduced.

Therefore, in this embodiment, as shown in FIGS. 3 and 4, a step recessed in the direction of the axis O is formed on the radially outer edge of the disk outer circumferential surface 41C and the cover outer circumferential surface 43C. More specifically, as shown in FIG. 3, the disk rear surface 41A has a circular main surface 61 centered on the axis O, an annular receding surface 63 surrounding the outer circumferential side of this main surface 61, and a receding surface 63. It has a stepped surface 62 that connects the surface 63 and the main surface 61 in the direction of the axis O. The retreating surface 63 is retreating from the main surface 61 in the direction of the axis O. More specifically, the retreating surface 63 is retreating in the direction away from the casing back surface 3A compared to the main surface 61. The retreating surface 63 is parallel to the main surface 61. Further, the retreating surface 63 has an annular shape continuous in the circumferential direction with respect to the axis O. The outer peripheral edge of the retreating surface 63 is connected to the disk outer peripheral surface 41C. The stepped surface 62 connects the outer peripheral edge of the main surface 61 and the inner peripheral edge of the retreating surface 63 in the direction of the axis O.

Similarly, as shown in FIG. 3, the casing back surface 3A has a circular main surface 71 centered on the axis O, and an annular inclined surface 72 surrounding the outer circumferential side of the main surface 71. The inclined surface 72 is inclined with respect to the axis O so as to move from the inner side to the outer side in the radial direction and toward the above-mentioned retreating surface 63 side. Further, in a cross-sectional view including the axis O, the inclined surface 72 extends in a planar shape. The radially inner edge (inner edge t1) of the inclined surface 72 is located radially inward than the radially inner edge of the retreating surface 63 described above. Further, the radially outer edge (outer edge t2) of the inclined surface 72 is located on one side of the retreating surface 63 in the axis O direction. Therefore, the inclined surface 72, the stepped surface 62, and the retreating surface 63 define a space V having a triangular shape in cross-section.

Furthermore, as shown in FIG. 4, the above-mentioned cover upstream surface 43B includes a circular main surface 61' centered on the axis O, and an annular retreating surface 63' surrounding the outer peripheral side of this main surface 61'. It has a step surface 62' that connects the retreating surface 63' and the main surface 61' in the direction of the axis O. The retreating surface 63' is retreating in the direction of the axis O with respect to the main surface 61'. More specifically, the retreating surface 63' is retreating in a direction away from the casing upstream surface 3B compared to the main surface 61'. The retreating surface 63' is parallel to the main surface 61'. Further, the retreating surface 63' has an annular shape continuous in the circumferential direction with respect to the axis O. An edge on the outer peripheral side of the retreating surface 63' is connected to the cover outer peripheral surface 43C. The step surface 62' connects the outer peripheral edge of the main surface 61' and the inner peripheral edge of the retreating surface 63' in the direction of the axis O.

Similarly, as shown in FIG. 4, the casing upstream surface 3B has a circular main surface 71' centered on the axis O, and an annular inclined surface 72' surrounding the outer peripheral side of the main surface 71'. ing. The inclined surface 72' is inclined with respect to the axis O so as to move from the inner side to the outer side in the radial direction toward the above-mentioned retreating surface 63' side. Further, in a cross-sectional view including the axis O, the inclined surface 72' extends in a planar shape. The radially inner edge (inner edge t1') of the inclined surface 72' is located radially inward than the radially inner edge of the retreating surface 63'. Further, the radially outer edge (outer edge t2') of the inclined surface 72' is located on the other side of the retreating surface 63 in the axis O direction. Therefore, a space V' having a triangular cross-sectional view is defined by the inclined surface 72', the step surface 62', and the retreating surface 63'.

In the above configuration, when the fluid flows from the inside in the radial direction to the outside in the flow path F1 between the disk back surface 41A as the first opposing surface P1 and the casing back surface 3A as the second opposing surface P2. , a portion of the fluid is trapped in the space V between the retreating surface 63 and the inclined surface 72. The trapped fluid forms a vortex within the space V. Specifically, as shown in FIG. 3, this vortex is turning from the inclined surface 72 to the stepped surface 62 via the retreating surface 63. Further, another vortex is formed between the disk outer circumferential surface 41C and the casing inner circumferential surface 3D (that is, within the flow path F3). Here, the fluid flowing through the flow path F1 includes a circumferential velocity component accompanying the rotation of the rotating body R. Therefore, the above-mentioned vortex is also in a rotating state while containing a circumferential velocity component. Due to the presence of this vortex, the velocity gradient between the rotating body R and the stationary body S can be made gentle. As a result, friction loss occurring between the rotating body R and the stationary body S can be reduced.

Further, in the above configuration, the flow path F2 between the cover upstream surface 43B as the first opposing surface P1' and the casing upstream surface 3B as the second opposing surface P2' is moved from the outside in the radial direction to the inside. When the fluid flows, a portion of the fluid is trapped in the space V' between the retreating surface 63' and the inclined surface 72'. The trapped fluid forms a vortex within the space V'. Specifically, as shown in FIG. 4, this vortex is turning from the inclined surface 72' to the stepped surface 62' toward the retreating surface 63'. Furthermore, other vortices are formed in the flow path F2 as well. This vortex moves from the inside in the radial direction to the outside in the flow path F2, then changes direction toward the casing upstream surface 3B, and is swirling toward the inside in the radial direction again. Here, the fluid flowing through the flow path F2 includes a circumferential velocity component accompanying the rotation of the rotating body R. Therefore, the above-mentioned vortex is also in a rotating state while containing a circumferential velocity component. Due to the presence of this vortex, the velocity gradient between the rotating body R and the stationary body S can be made gentle. As a result, friction loss occurring between the rotating body R and the stationary body S can be reduced.

Further, according to the above configuration, the radially inner edge (inner edge t1) of the inclined surface 72 is located radially inner than the radially inner edge of the retreating surface 63. Thereby, when the fluid flows from the inside in the radial direction to the outside in the flow path F1, the fluid can be guided to the inclined surface 72 from a position radially inside of the retreating surface 63 as a starting point. That is, the fluid guided by the inclined surface 72 can be quickly guided between the inclined surface 72 and the retreating surface 63 (space V). Therefore, a vortex can be formed more stably within this space V.

The first embodiment of the present invention has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present invention. For example, in the first embodiment, the inner edge t1 of the inclined surface 72 (or the inner edge t1' of the inclined surface 72') is the radially inner edge of the retreating surface 63 (or the retreating surface 63'). The configuration has been described in which it is located radially inward from the edge. However, it is also possible to adopt the configuration shown in FIG. 5 or 6. In the example of FIG. 5, the inner edge t1 is at the same position in the radial direction as the radially inner edge of the retreating surface 63. Further, in the example of FIG. 6, the inner edge t1 is located radially outer than the radially inner edge of the retreating surface 63. According to such a configuration, a sufficient distance between the inclined surface 72 and the retreating surface 63 can be ensured. Thereby, even if, for example, the rotating body R is displaced in a direction approaching the stationary body S, the possibility that the rotating body R and the stationary body S come into contact can be reduced. As a result, centrifugal compressor 100 can be operated more stably. Although FIGS. 5 and 6 only illustrate the inclined surface 72, the inclined surface 72' can also have the same configuration as described above.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. 7. Note that the same components as in the first embodiment are given the same reference numerals, and detailed explanations will be omitted. As shown in FIG. 7, in this embodiment, the configuration of the inclined surface 72B is different from that in the first embodiment. The inclined surface 72B is inclined toward the retreating surface 63 from the inner side to the outer side in the radial direction, and has a curved shape. More specifically, the inclined surface 72B has a curved shape that is convex on the side away from the retreating surface 63. The radially inner edge of the inclined surface 72B and the radially outer edge of the main surface 71 are continuously connected. Similarly, the radially outer edge of the inclined surface 72B and the casing inner peripheral surface 3D are continuously connected. In other words, no step or the like is formed in these connecting portions.

According to the above configuration, since the inclined surface 72B has a curved shape, the fluid can be guided more smoothly along the inclined surface 72B. Thereby, the vortex can be held more stably between the retreating surface 63 and the inclined surface 72B.

The second embodiment of the present invention has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present invention. For example, in the second embodiment, a configuration is described in which the inclined surface 72B is provided on the casing back surface 3A as the second opposing surface P2. However, similarly to the first embodiment, it is also possible to provide a curved surface similar to the inclined surface 72B on the casing upstream surface 3B as the second opposing surface P2'. Even in this case, the same effects as above can be obtained.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. 8. Note that the same configurations as in each of the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 8, in this embodiment, a plurality (two) of the above-mentioned step surfaces 62 and retreating surfaces 63 are provided. More specifically, an inner space V1 similar to the space V described in the first embodiment is formed by the inner step surface 62A and the inner retreating surface 63A, which are located relatively inward in the radial direction. Further, an outer step surface 62B extending parallel to the inner step surface 62A is connected to the radially outer edge of the inner retreating surface 63A. An outer receding surface 63B extending parallel to the inner receding surface 63A is connected to the outer stepped surface 62B. The outer retreating surface 63B is set back from the casing back surface 3A more than the inner retreating surface 63A.

According to the above configuration, by forming the plurality of retreating surfaces 63, vortices can be formed in the inner space V1 and the outer space V2, respectively, from the inside in the radial direction to the outside. As a whole, a plurality of vortices can be formed. As a result, a plurality of vortices are present between the inclined surface 72 and the retreating surface 63. Each vortex contains a circumferential velocity component accompanying the rotation of the rotating body R. Therefore, according to the above configuration, the friction loss occurring between the rotating body R and the stationary body S can be further reduced.

The third embodiment of the present invention has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present invention. For example, in the above embodiment, two stepped surfaces 62 (inner stepped surface 62A and outer stepped surface 62B) and two setback surfaces 63 (inner setback surface 63A and outer setback surface 63B) are formed. explained. However, the number of step surfaces 62 and retreating surfaces 63 (that is, the number of steps) is not limited to two, and may be three or more. Further, in the third embodiment, a configuration has been described in which a plurality of stepped surfaces 62 and a plurality of retreating surfaces 63 are provided on the disk back surface 41A as the first opposing surface P1. However, similarly to the first embodiment, it is also possible to provide the cover upstream surface 43B as the first opposing surface P1' with the same configuration as the plurality of stepped surfaces 62 and the plurality of retreating surfaces 63. Even in this case, the same effects as above can be obtained.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. 9. Note that the same configurations as in each of the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 9, this embodiment differs from the configuration described in the third embodiment in that a plurality (two) of grooves 70R are formed on the inclined surface 72. . Specifically, the groove 70R is formed at a position that overlaps the radially outer edge of each retreating surface 63 in the radial direction. Each groove 70R has an annular shape centered on the axis O. Further, each groove 70R is recessed on the inclined surface 72 in a direction away from the retreating surface 63. The groove has a semicircular cross-sectional shape.

According to the above configuration, since the groove 70R is formed in the inclined surface 72, even if the rotating body R is displaced in a direction approaching the stationary body S, the groove 70R is Since this space is secured, it is possible to reduce the possibility that the rotating body R and the stationary body S will come into contact with each other. As a result, centrifugal compressor 100 can be operated more stably.

The fourth embodiment of the present invention has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present invention. For example, in the fourth embodiment, the configuration in which the groove 70R is formed in the casing back surface 3A as the second opposing surface P2 has been described. However, similarly to the first embodiment, it is also possible to provide the same configuration as the groove 70R on the casing upstream surface 3B as the second opposing surface P2'. Even in this case, the same effects as above can be obtained.

100 Centrifugal compressor (rotating machine)
1 Rotating shaft 2 Fluid flow path 3 Casing 3A Casing back surface 3B Casing upstream surface 3D Casing inner peripheral surface 4 Impeller 5 Journal bearing 6 Thrust bearing 7 Intake port 8 Exhaust port 10 Recess 11 Stationary side recess 21 Suction flow path 22 Compression flow path 23 Diffuser flow path 24 Return bend portion 25 Guide flow path 41 Disk 41A Disk back surface 41C Disk outer peripheral surface 42 Blade 43 Cover 43B Cover upstream surface 43C Cover outer peripheral surface 50 Return vane 61, 61', 71, 71' Main surface 62, 62' Step surface 63, 63' Recessed surface 62A Inner step surface 62B Outer step surface 63A Inner recessed surface 63B Outer recessed surface 72, 72' Inclined surface F1, F2, F3 Flow path O Axis P1, P1' First opposing surface P2, P2 'Second opposing surface R Rotating body S Stationary body t1, t1' Inner edge t2, t2' Outer edge V, V' Space V1 Inner space V2 Outer space

Claims (7)

a rotating body that is rotatable around an axis and has a first opposing surface that extends in a plane that intersects the axis;
a stationary body having a second opposing surface that faces the first opposing surface from the axial direction and forms a flow path through which fluid flows between the first opposing surface;
Equipped with
The first opposing surface is
a first main surface extending in a direction perpendicular to the axis;
a retreating surface that is provided continuously in the circumferential direction on the radially outer edge of the first principal surface on the radially outer side with respect to the axis, and that is retreated from the first principal surface in the axial direction;
has
The second opposing surface is
a second main surface that faces the first main surface in the axial direction and extends in a direction perpendicular to the axis;
is connected to the radially outer side of the second main surface, and is inclined with respect to the axis toward the retreating surface from the radially inner side to the outer side with respect to the axis, and is more radial than the retreating surface. has an inclined surface extending outward in the direction;
A rotating machine in which a space extending annularly around the axis is defined by the retreating surface and the inclined surface. a rotating body that is rotatable around an axis and has a first opposing surface that extends in a plane that intersects the axis;
a stationary body having a second opposing surface that faces the first opposing surface from the axial direction and forms a flow path through which fluid flows between the first opposing surface;
Equipped with
The first opposing surface has a receding surface that is continuously provided in the circumferential direction at a radially outer edge with respect to the axis and is retreated from the first opposing surface in the axial direction,
The second opposing surface has an inclined surface that is inclined with respect to the axis so as to move toward the retreating surface from the inside in the radial direction to the outside with respect to the axis,
In the rotating machine, the inclined surface has a curved surface shape that is convex on the side away from the retreating surface. a rotating body that is rotatable around an axis and has a first opposing surface that extends in a plane that intersects the axis;
a stationary body having a second opposing surface that faces the first opposing surface from the axial direction and forms a flow path through which fluid flows between the first opposing surface;
Equipped with
The first opposing surface has a receding surface that is continuously provided in the circumferential direction at a radially outer edge with respect to the axis and is retreated from the first opposing surface in the axial direction,
The second opposing surface has an inclined surface that is inclined with respect to the axis so as to move toward the retreating surface from the inside in the radial direction to the outside with respect to the axis,
The rotating body has a plurality of retreating surfaces arranged from the inner side to the outer side in the radial direction,
The rotary machine is further retreated in the axial direction from the first opposing surface as the retreating surface is located on the outer side in the radial direction. 4. The radially inner edge of the inclined surface is located radially inner than the radially inner edge of the retreating surface in the axial direction. Rotating machinery as described. The rotating machine according to any one of claims 1 to 3, wherein the radially inner edge of the inclined surface is located at the same position as the radially inner edge of the retreating surface in the axial direction. The radially inner edge of the inclined surface is located radially outer than the radially inner edge of the retreating surface in the axial direction. Rotating machinery as described. A groove is formed in the inclined surface at a position corresponding to the radially outer edge of the retreating surface in the radial direction with respect to the axis, and is recessed from the inclined surface in the axial direction and continuous in the circumferential direction. The rotating machine according to any one of claims 1 to 6.

Images