In addition, the ring groove 74 m of the elastic ring portion 74 is open inward in the radial direction Dr on the flow path 100 side of the fluid G Accordingly, when the fluid G leaks out of the flow path 100 side, the fluid G flows into the ring groove 74 m. Since the fluid G flows into the ring groove 74 m, the inner peripheral surface 74 f of the elastic ring portion 74 is pressed inward in the hole diameter direction Ds. Therefore, it is possible to improve the sealing performance between the first seal member 71 and the shaft portion 42.
In addition, the frame 50 includes the plurality of seal holding members 55 stacked along the direction of the central axis Cs. The first seal member 71 can be accommodated in the accommodation portion 58 from the holding member first surface 55 f side of the respective seal holding members 55. In this manner, assembling work can be more easily carried out, compared to a case where the first seal member 71 is assembled outward from the inside in the hole diameter direction Ds of the holding member through-hole 55 h.
In addition, in the first seal member 71, the lip portion 76 extending outward in the hole diameter direction Ds from the seal portion main body 73 is interposed between the seal holding member 55 having the first seal member 71 incorporated therein and other members. Accordingly, the first seal member 71 is prevented from interfering with the shaft portion 42. In addition, the fluid G is prevented from leaking out of the clearance between the seal holding member 55 and other members.
 In addition, the third seal member 79 located on the outer side in the hole diameter direction Ds of the first seal member 71 can more reliably prevent the fluid G from leaking out of the clearance between the plurality of stacked seal holding members 55 and other members.
In addition, the seal space 80 is formed between the first seal member 71 and the second seal member 72 by the hole side recess portion 562. When the fluid G leaks out of the flow path 100 side, the fluid G flows into the seal space 80. In this manner, the fluid G can be prevented from leaking outward.
Second Embodiment

Next, referring to FIG. 6, an inlet guide vane according to a second embodiment will be described. In the second embodiment, the same reference numerals will be given to the configuration elements which are the same as those according to the first embodiment, and detailed description thereof will be omitted. The inlet guide vane according to the second embodiment is different from that according to the first embodiment in that the inlet guide vane has a different configuration of the seal portion.
That is, as shown in FIG. 6, similar to the inlet guide vane 24 according to the first embodiment, an inlet guide vane 24B according to the second embodiment includes the frame 50 and the plurality of movable vanes 40.
The outer peripheral portion of the frame 50 has the vane holder 51. The vane holder 51 has the insertion holes 51 h formed so as to extend along the radial direction Dr of the frame 50 at a plurality of locations formed at an interval in the circumferential direction.
 The movable vane 40 is supported by the first bearing portion 60A and the second bearing portion 60B which are disposed in the insertion hole 51 h so that the shaft portion 42 is rotatable around the central axis Cs.
A seal portion 70B is disposed between the first bearing portion 60A and the second bearing portion 60B. A seal space 80B is formed between the first seal member 71 and the second seal member 72 of the seal portion 70B by a hole side recess portion 562 formed in the intermediate member 56.
The seal portion 70B includes a sensor 90 which detects that the fluid G inside the flow path 100 enters the seal space 80B. The sensor 90 detects that the fluid G enters the seal space 80B by detecting the pressure, the temperature, or the substances configuring the fluid G inside the seal space 80B.
According to the configuration as described above, similar to the first embodiment, the sealing performance in the shaft portion 42 of the movable vane 40 can be improved. Furthermore, the sensor 90 can detect that the fluid G leaks to the clearance between the insertion hole 51 h and the shaft portion 42 from the inside of the flow path 100. In this manner, in a case where the sensor 90 detects the leakage of the fluid G, maintenance work for the seal portion 70B can be carried out at a proper timing by stopping the operation of the centrifugal compressor system 1.
 Third Embodiment

Next, referring to FIG. 7, an inlet guide vane according to a third embodiment will be described. In the third embodiment, the same reference numerals will be given to the configuration elements which are the same as those according to the first and second embodiments, and detailed description thereof will be omitted. The inlet guide vane according to the third embodiment is different from those according to the first and second embodiments in that the inlet guide vane has a different configuration of the seal portion.
That is, as shown in FIG. 7, similar to the inlet guide vane 24 according to the first embodiment, an inlet guide vane 24C according to the third embodiment includes the frame 50 and the plurality of movable vanes 40.
The outer peripheral portion of the frame 50 has the vane holder 51. The vane holder 51 has the insertion holes 51 h formed so as to extend along the radial direction Dr of the frame 50 at a plurality of locations formed at an interval in the circumferential direction.
The movable vane 40 is supported by the first bearing portion 60A and the second bearing portion 60B which are disposed in the insertion hole 51 h so that the shaft portion 42 is rotatable around the central axis Cs.
A seal portion 70C is disposed between the first bearing portion 60A and the second bearing portion 60B. A seal space 80C is formed between the first seal member 71 and the second seal member 72 of the seal portion 70C by the hole side recess portion 562 formed in the intermediate member 56.
 The intermediate member 56 has a communication hole 568 which allows the outside and the hole side recess portion 562 to communicate with each other. A sealing fluid supply unit 95 is connected to the communication hole 568. The sealing fluid supply unit 95 supplies a sealing fluid Gs from the outside to the seal space 80C of the clearance between the insertion hole 51 h and the shaft portion 42.
The sealing fluid supply unit 95 pressurizes the seal space 80C by supplying the sealing fluid Gs. It is preferable that the pressure inside the pressurized seal space 80C is lower than the pressure inside the flow path 100 and higher than the pressure (atmospheric pressure) outside the frame 50.
According to the configuration as described above, similar to the above-described first embodiment, the sealing performance in the shaft portion 42 of the movable vane 40 can be improved. Furthermore, the sealing fluid Gs is fed from the outside into the seal space 80C between the first seal member 71 and the second seal member 72 so as to pressurize the inside of the seal space 80C. In this manner, a pressure difference decreases between the pressure of the fluid G inside the flow path 100 and the pressure inside the seal space 80C. As a result, it is possible to prevent the fluid G inside the flow path 100 from flowing into the portion between the first seal member 71 and the second seal member 72. Accordingly, the sealing performance can be further improved. In this manner, it is possible to prevent the first seal member 71 from being damaged.
 Hitherto, the embodiments according to the present invention have been described in detail with reference to the drawings. However, the respective configurations and combinations thereof in the respective embodiments are merely examples. Additions, omissions, substitutions, and modifications of the configurations are available within the scope not departing from the gist of the present invention. In addition, the present invention is not limited by the embodiments, and is limited only by the appended claims.
For example, the inlet guide vanes 24, 24B, and 24C which are shown in the above-described embodiments are applicable not only to a geared compressor configuring the centrifugal compressor system 1 but also to an axial flow compressor or a gas turbine.
INDUSTRIAL APPLICABILITY

According to the inlet guide vane and the compressor which are described above, it is possible to improve the sealing performance in the shaft portion of the movable vane of the inlet guide vane.
 REFERENCE SIGNS LIST

1: centrifugal compressor system

2: drive shaft

3: driven shaft

4: compression unit

5: first driven shaft

6: second driven shaft

7 a, 7 b: first stage compression unit (compressor)

8: second stage compression unit

9: third stage compression unit

10: speed increaser

11: drive gear

12: first driven gear

13: second driven gear

14: first intermediate gear

15: second intermediate gear

17: first intermediate shaft

18: second intermediate shaft

19: drive source

20: casing

23: gas inlet

24, 24B, 24C: inlet guide vane

25, 37, 38: impeller

26: actuator

27: first stage heat exchanger

27 a: inlet nozzle

27 b: outlet nozzle

28: second stage heat exchanger

30: first stage pipe

31 a, 31 b: first stage compression unit discharge pipe

32: second stage compression unit suction pipe

33: second stage pipe

34: second stage compression unit discharge pipe

35: third stage compression unit suction pipe

36: third stage compression unit discharge pipe

40: movable vane

41: vane main body

41 a, 41 b: end portion

42: shaft portion

42 f: outer peripheral surface

42 s: tip portion

44: center hub

50: frame

50 f: outer peripheral surface

50 g: inner peripheral surface

51: vane holder

51 f: inner peripheral surface

51 h: insertion hole

52: base portion

52 f: outer peripheral surface

52 h: base portion through-hole

53: outer peripheral recess portion

53 b: bottom surface

54: inner peripheral recess portion

54 b: bottom surface

55, 55A, 55B: seal holding member

55 f: holding member first surface

55 g: holding member second surface

55 h: holding member through-hole

56: intermediate member

56 a: intermediate member first surface

56 b: intermediate member second surface

56 d: flange portion

56 h: intermediate member through-hole

561: intermediate recess portion

561 b: bottom surface

562: hole side recess portion

563: intermediate member groove

568: communication hole

57: seal pressure member

57 b: second surface

57 h: through-hole

571: insertion cylinder portion

58: accommodation portion

58 a: inner peripheral side stepped portion

58 b: outer peripheral side stepped portion

59: holding member groove

60: bearing portion

60A: first bearing portion

60B: second bearing portion

61: bolt

65: link plate

65 a, 65 b: end portion

66: drive pin

67: turning ring

70, 70B, 70C: seal portion

71: first seal member

72: second seal member

73: seal portion main body

74: elastic ring portion

74 f: inner peripheral surface

74 m: ring groove

75: biasing member

76: lip portion

77: seal cap

77 m: cap groove

78: seal ring

79, 79A, 79B, 79C: third seal member

80, 80B, 80C: seal space

90: sensor

95: sealing fluid supply unit

100: flow path

Cs: central axis

Dr: radial direction

Ds: hole diameter direction

G: fluid

Gs: sealing fluid

P: plant

1.  2. The inlet guide vane according to claim 1, wherein the seal portion includes a first seal member and a second seal member which are located at an interval in the direction of the central axis.
3. The inlet guide vane according to claim 2, wherein the first seal member and the second seal member have seal structures which are different from each other.
4. The inlet guide vane according to claim 3, wherein the first seal member is located at a position closer to the vane main body than the second seal member, and has sealing performance higher than that of the second seal member.
5. The inlet guide vane according to claim 2, wherein at least any one of a hole side recess portion formed on an inner peripheral surface of the insertion hole and recessed outward in a radial direction and a shaft side recess portion formed on an outer peripheral surface of the shaft portion and recessed inward in the radial direction is formed between the first seal member and the second seal member.
6. The inlet guide vane according to claim 2, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
7. The inlet guide vane according to claim 2, further comprising: a sealing fluid supply unit that is disposed between the first seal member and the second seal member, and that is configured to supply a sealing fluid from the outside to a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
 8. The inlet guide vane according to claim 1, wherein the seal portion includes an elastic ring portion which is disposed outward in a radial direction of the shaft portion, which has an annular shape continuous in a circumferential direction, and which has a groove open toward a side where the vane main body is located with respect to the frame, and a biasing member which is disposed in the groove, and which is configured to cause an inner peripheral surface of the elastic ring portion to be biased inward in the radial direction toward the shaft portion.
9. A compressor comprising: the inlet guide vane according to claim
 1. 10. The inlet guide vane according to claim 3, wherein at least any one of a hole side recess portion formed on an inner peripheral surface of the insertion hole and recessed outward in a radial direction and a shaft side recess portion formed on an outer peripheral surface of the shaft portion and recessed inward in the radial direction is formed between the first seal member and the second seal member.
11. The inlet guide vane according to claim 4, wherein at least any one of a hole side recess portion formed on an inner peripheral surface of the insertion hole and recessed outward in a radial direction and a shaft side recess portion formed on an outer peripheral surface of the shaft portion and recessed inward in the radial direction is formed between the first seal member and the second seal member.
 12. The inlet guide vane according to claim 3, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
13. The inlet guide vane according to claim 4, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
14. The inlet guide vane according to claim 5, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
15. The inlet guide vane according to claim 10, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion.
16. The inlet guide vane according to claim 11, further comprising: a sensor that is disposed between the first seal member and the second seal member, and that is configured to detect a fluid entering a clearance between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion..
