Patent Publication Number: US-11041401-B2

Title: Inlet guide vane and compressor

Description:
TECHNICAL FIELD 
     This invention relates to an inlet guide vane and a compressor. 
     BACKGROUND ART 
     For example, a centrifugal compressor circulates a fluid inside a rotating impeller, and compresses the fluid in a gaseous state by utilizing a centrifugal force generated when the impeller is rotated. This centrifugal compressor includes a variable type inlet guide vane (IGV) which can adjust a flow rate of the fluid introduced from the outside by changing an angle of an inlet guide vane in order to broaden an operation range of the centrifugal compressor. 
     The inlet guide vane is disposed in an inlet flow path which introduces the fluid from the outside into a housing of the centrifugal compressor. The inlet guide vane includes a vane case fixed at the inlet flow path, and a plurality of movable vanes which are supported by the vane case and whose opening degree can be adjusted. Each of the movable vanes has a vane main body and a shaft portion integrally formed with the vane main body. In the movable vane, the shaft portion is supported by a shaft hole formed in the vane case so as to be rotatable via a bearing of a bush. 
     Incidentally, a minute clearance is formed between the bearing and the shaft portion so that the shaft portion of the movable vane is rotatable inside the shaft hole. Through this minute clearance, the fluid leaks outward. 
     Therefore, for example, Patent Document 1 discloses a configuration where a seal member is provided in order to prevent the fluid from flowing out through the clearance of the shaft portion of the movable vane. 
     CITATION LIST 
     Patent Literature 
     [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2015-21477 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in a case where the fluid inside the flow path has high pressure and a pressure difference from an atmosphere outside the flow path is great, sealing performance in the seal member may become poor due to the pressure difference. Therefore, it is desirable to improve the sealing performance in the shaft portion of the movable vane. 
     The present invention provides an inlet guide vane and a compressor which can improve sealing performance in a shaft portion of a movable vane. 
     Solution to Problem 
     According to a first aspect of the present invention, there is provided an inlet guide vane including a movable vane that has a vane main body and a shaft portion disposed in an end portion of the vane main body, a frame that has an insertion hole into which the shaft portion is to be inserted, a plurality of bearing portions that are arranged inside the insertion hole at an interval in a direction of a central axis of the shaft portion, and that support the shaft portion so as to be rotatable around the central axis with respect to the frame, and a seal portion that is located inside the insertion hole between the plurality of bearing portions in the direction of the central axis, and that is configured to seal between the insertion hole and the shaft portion. 
     According to this configuration, the seal portion located between the plurality of bearing portions prevents a fluid inside a flow path from leaking outward after passing between an inner peripheral surface of the insertion hole and an outer peripheral surface of the shaft portion. Only the fluid passing through a clearance between the bearing portion and the outer peripheral surface of the shaft portion arrives at the seal portion. Accordingly, the seal portion is less likely to be exposed to the fluid, and is less likely to be affected by the fluid. Therefore, it is possible to continuously achieve high sealing performance by preventing the seal portion from being degraded. 
     In the inlet guide vane according to a second aspect of the present invention, in the first aspect, the seal portion may include a first seal member and a second seal member which are located at an interval in the direction of the central axis. 
     According to this configuration, the first seal member and the second seal member allow the seal portion to have a double configuration. Therefore, the sealing performance can be improved. 
     In the inlet guide vane according to a third aspect of the present invention, in the second aspect, the first seal member and the second seal member may have seal structures which are different from each other. 
     According to this configuration, the first seal member and the second seal member are caused to have mutually different seal structures, thereby configuring the seal portion having a plurality of sealing characteristics. As a result, higher sealing performance is ensured. 
     In the inlet guide vane according to a fourth aspect of the present invention, in the third aspect, the first seal member may be located at a position closer to the vane main body than the second seal member, and may have sealing performance higher than that of the second seal member. 
     According to this configuration, the first seal member having the high sealing performance can effectively prevent the fluid from leaking out of the vane main body side. Furthermore, the second seal member is caused to function as a backup member for sealing the clearance against only the fluid passing through the first seal member. In this manner, even if the sealing performance of the second seal member is suppressed, the sealing performance of the seal portion can be ensured as a whole. As a result, cost for the second seal member can be minimized. 
     In the inlet guide vane according to a fifth aspect of the present invention, in any one of the second to fourth aspects, 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 may be formed between the first seal member and the second seal member. 
     According to this configuration, between the first seal member and the second seal member, a space is formed in which a cross-sectional area of the clearance between the inner peripheral surface of the insertion hole and the outer peripheral surface of the shaft portion is widened by at least one of the hole side recess portion and the shaft side recess portion. Therefore, even in a case where the fluid leaks out of the flow path side, the fluid is reserved in this space, and the fluid can be prevented from leaking outward. In this manner, for example, even if the fluid flows in from the first seal member side and the sealing performance is degraded in the first seal member, the sealing performance as the whole seal portion can be prevented from being degraded. 
     In any one of the second to fifth aspects, the inlet guide vane according to a sixth aspect of the present invention may further include 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. 
     According to this configuration, the sensor can detect that the fluid leaks out of the flow path side. 
     In any one of the second to sixth aspects, the inlet guide vane according to a seventh aspect of the present invention may further include 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. 
     According to this configuration, the sealing fluid is fed from the outside to a portion between the first seal member and the second seal member. In this manner, the fluid inside the flow path can be prevented from flowing into the portion between the first seal member and the second seal member. 
     In the inlet guide vane according to an eighth aspect of the present invention, in any one of the first to seventh aspects, the seal portion may include 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. 
     According to this configuration, the inner peripheral surface of the elastic ring portion is biased inward in the radial direction by the biasing member. Accordingly, the sealing performance between the seal portion and the shaft portion can be improved. In addition, the groove of the elastic ring portion is open to the side where the vane main body on the flow path side of the fluid is located. Therefore, when the fluid leaks out of the flow path side, the fluid flows into the groove. Since the fluid flows into the groove, the inner peripheral surface of the elastic ring portion is pressed inward in the radial direction. Therefore, the sealing performance between the seal portion and the shaft portion can be improved. 
     According to a ninth aspect of the present invention, there is provided a compressor including the above-described inlet guide vane. 
     According to this configuration, the seal portion located between the plurality of bearing portions prevents the fluid inside the flow path from leaking outward after passing between the inner peripheral surface of the insertion hole and the outer peripheral surface of the shaft portion suppress. In this manner, the inlet guide vane is also effectively applicable to the compressor in which flammable gas is used as the fluid. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to improve the sealing performance in the shaft portion of the movable vane. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view showing a schematic configuration of a compressor system according to an embodiment of this invention. 
         FIG. 2  is a view when an inlet guide vane according to the embodiment of this invention is viewed in a direction of a central axis. 
         FIG. 3  is a half sectional view taken along the direction of the central axis of the inlet guide vane according to the embodiment of this invention. 
         FIG. 4  is a sectional view showing a main portion of an inlet guide vane according to a first embodiment of this invention. 
         FIG. 5  is an enlarged sectional view showing a portion in  FIG. 5 . 
         FIG. 6  is a sectional view showing a main portion of an inlet guide vane according to a second embodiment of this invention. 
         FIG. 7  is a sectional view showing a main portion of an inlet guide vane according to a third embodiment of this invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Hereinafter, an inlet guide vane and a compressor according to the present invention will be described with reference to the drawings. As shown in  FIG. 1 , a centrifugal compressor system  1  includes a drive source  19  for generating power, a drive shaft  2 , a driven shaft  3 , a compression unit  4 , and a speed increaser  10 . 
     The drive shaft  2  is driven to be rotatable around a central axis thereof by the drive source  19 . For example, as the drive source  19 , a steam turbine or a motor can be used. 
     The driven shaft  3  is driven to be rotatable around the central axis by the power transmitted from the speed increaser  10 . The driven shafts  3  are respectively located on both sides across the drive shaft  2 . The driven shaft  3  has a first driven shaft  5  and a second driven shaft  6  which respectively extend parallel to the drive shaft  2 . 
     The speed increaser  10  increases rotation speed of the drive shaft  2 , and transmits the rotation speed to the first driven shaft  5  and the second driven shaft  6 . Inside a casing  20 , the speed increaser  10  includes a drive gear  11 , a first driven gear  12 , a second driven gear  13 , a first intermediate gear  14 , and a second intermediate gear  15 . 
     The drive gear  11  is disposed in a tip portion of the drive shaft  2  inserted into the casing  20  after penetrating the casing  20 , and is rotated integrally with the drive shaft  2 . Here, the drive shaft  2  is supported by the casing  20  via a bearing (not shown). 
     The first driven gear  12  is disposed integrally with the first driven shaft  5  in the intermediate portion in the direction of the central axis of the first driven shaft  5 . The second driven gear  13  is disposed integrally with the second driven shaft  6  in the intermediate portion in the direction of the central axis of the second driven shaft  6 . The first driven shaft  5  and the second driven shaft  6  are supported by the casing  20  via a bearing (not shown). The first driven gear  12  and the second driven gear  13  are located on both sides across the drive gear  11  at an interval therebetween. 
     The first intermediate gear  14  is located between the drive gear  11  and the first driven gear  12 , and meshes with the drive gear  11  and the first driven gear  12 . The second intermediate gear  15  is located between the drive gear  11  and the second driven gear  13  and meshes with the drive gear  11  and the second driven gear  13 . The first intermediate gear  14  and the second intermediate gear  15  are so-called idle gears. The first intermediate gear  14  is disposed integrally with a first intermediate shaft  17  rotatably supported by the casing  20  via a bearing (not shown). The second intermediate gear  15  is disposed integrally with a second intermediate shaft  18  rotatably supported by the casing  20  via a bearing (not shown). 
     In the speed increaser  10  configured in this way, if the drive shaft  2  is rotated by a drive force of the drive source  19 , the drive gear  11  is rotated integrally with the drive shaft  2 . The rotation of the drive gear  11  is transmitted to the first driven gear  12  and the second driven gear  13  via the first intermediate gear  14  and the second intermediate gear  15 . In this manner, the first driven gear  12  and the second driven gear  13  are rotated. In conjunction with the rotation of the first driven gear  12 , the first driven shaft  5  is rotated. In conjunction with the rotation of the second driven gear  13 , the second driven shaft  6  is rotated. That is, since the drive shaft  2  is driven, the first driven shaft  5  and the second driven shaft  6  are rotated. 
     The compression unit  4  is driven by power transmitted from the drive shaft  2  to the driven shaft  3  via the speed increaser  10 . The compression unit  4  includes two first stage compression units (compressors)  7   a  and  7   b , a second stage compression unit  8 , and a third stage compression unit  9 . 
     The first stage compression units  7   a  and  7   b  are compression units into which a fluid G initially flows in the centrifugal compressor system  1 . The first stage compression units  7   a  and  7   b  are respectively disposed in end portions on both sides in the direction of the central axis of the first driven shaft  5 . The two first stage compression units  7   a  and  7   b  have the same configuration. The first stage compression units  7   a  and  7   b  according to the present embodiment respectively have a gas inlet  23 , an inlet guide vane  24 , and an impeller  25 . 
     The gas inlet  23  has a continuous cylindrical shape. The gas inlet  23  internally forms an inlet flow path which introduces the fluid G serving as a compression target from the outside. 
     The impeller  25  is attached to the first driven shaft  5 , and compresses the fluid G supplied from the gas inlet  23 . 
     The inlet guide vane  24  is disposed in the gas inlet  23 . The inlet guide vane  24  controls a flow rate of the fluid G passing through the gas inlet  23 . 
     The second stage compression unit  8  is disposed in end portion on a side opposite to a side where the drive source  19  is disposed in the second driven shaft  6 . The second stage compression unit  8  has an impeller  37  for compressing the fluid G. 
     The third stage compression unit  9  is disposed on a side which is the same as the side where the drive source  19  is disposed in the second driven shaft  6 . The third stage compression unit  9  has an impeller  38  for compressing the fluid G. 
     Next, a connection configuration between the compression units will be described. 
     The two first stage compression units  7   a  and  7   b  are connected to the second stage compression unit  8  via a first stage pipe  30 . The first stage pipe  30  is configured to include two first stage compression unit discharge pipes  31   a  and  31   b  and a second stage compression unit suction pipe  32 . 
     A first stage heat exchanger  27  is interposed between the first stage compression unit discharge pipes  31   a  and  31   b  and the second stage compression unit suction pipe  32 . The first stage heat exchanger  27  includes two inlet nozzles  27   a  and one outlet nozzle  27   b . The first stage compression unit discharge pipes  31   a  and  31   b  are respectively connected to the two inlet nozzles  27   a . The second stage compression unit suction pipe  32  is connected to the outlet nozzle  27   b . That is, the first stage heat exchanger  27  has a function to cool the double system fluid G discharged from the two first stage compression units  7   a  and  7   b  configuring the first stage compression units  7   a  and  7   b , and to merge the double system fluid G so as to be the single system fluid G. The fluid G is intermediately cooled by the first stage heat exchanger  27  during a compression process. Accordingly, power needed to drive the centrifugal compressor system  1  is reduced. 
     The second stage compression unit  8  is connected to the third stage compression unit  9  via the second stage pipe  33 . The second stage pipe  33  is configured to include a second stage compression unit discharge pipe  34  and a third stage compression unit suction pipe  35 . 
     A second stage heat exchanger  28  for cooling the fluid G discharged from the second stage compression unit  8  is disposed between the second stage compression unit discharge pipe  34  and the third stage compression unit suction pipe  35 . The fluid G is intermediately cooled by the second stage heat exchanger  28  during the compression process. Accordingly, the power needed to drive the centrifugal compressor system  1  is reduced. 
     The third stage compression unit discharge pipe  36  is connected to the impeller  38  of the third stage compression unit  9 . The third stage compression unit discharge pipe  36  is connected to a predetermined plant P serving as a supply destination of the fluid G. 
     In the centrifugal compressor system  1  as described above, the fluid G to be compressed is introduced from the two gas inlets  23  and  23  configuring the first stage compression units  7   a  and  7   b , and is compressed in the two first stage compression units  7   a  and  7   b.    
     The fluid G compressed in the first stage compression units  7   a  and  7   b  passes through the first stage compression unit discharge pipes  31   a  and  31   b , and merges after being introduced to the first stage heat exchanger  27 . The merged fluid G is introduced to the second stage compression unit  8  through the second stage compression unit suction pipe  32  after the being intermediately cooled by the first stage heat exchanger  27 . 
     The fluid G is compressed in the second stage compression unit  8 . Thereafter, the fluid G is fed to the second stage heat exchanger  28  through the second stage compression unit discharge pipe  34 . In the second stage heat exchanger  28 , the fed fluid G is intermediately cooled. The intermediately cooled fluid G is introduced into the third stage compression unit  9  through the third stage compression unit suction pipe  35 . 
     After being compressed in the third stage compression unit  9 , the fluid G is supplied to the predetermined plant P serving as a demand destination of the compressed fluid G through the third stage compression unit discharge pipe  36 . 
     Next, the inlet guide vane  24  will be described in detail. 
     As shown in  FIGS. 2 to 4 , the inlet guide vane  24  includes a frame  50 , a plurality of movable vanes  40 , a bearing portion  60 , and a seal portion  70 . 
     As shown in  FIG. 2 , the frame  50  is a vane case having a cylindrical shape. The frame  50  is connected to a cylindrical body configuring the gas inlet  23  (refer to  FIG. 1 ). In this manner, a portion of a flow path  100  of the fluid G flowing inside the gas inlet  23  is formed. An outer peripheral portion of the frame  50  has a vane holder  51 . A plurality of insertion holes  51   h  penetrating the frame  50  in a radial direction Dr are formed in the vane holder  51 . The insertion holes  51   h  are formed at an interval in the circumferential direction. The movable vane  40  can be attached to the insertion hole  51   h . Specifically, a shaft portion  42  (to be described later) of the movable vane  40  can be inserted into the insertion hole  51   h.    
     The movable vane  40  is rotatably disposed with respect to the frame  50 . The plurality of movable vanes  40  are disposed at an interval in the circumferential direction. Each of the movable vanes  40  has a vane main body  41  and the shaft portion  42 . 
     The vane main body  41  is disposed on the inner side (first side) in the radial direction Dr with respect to the frame  50 . The vane main body  41  is located by aligning a vane length direction thereof with the radial direction Dr of the frame  50 . In a state where the end portion  41   b  located on the inner side in the radial direction Dr leaves a clearance form a center hub  44  disposed in a central portion of the frame  50 , the vane main body  41  is rotatable around a central axis Cs of the shaft portion  42 . 
     The shaft portion  42  is disposed integrally with the end portion  41   a  in the vane length direction which is located on the outer side (second side) in the radial direction Dr with respect to the vane main body  41 . The shaft portion  42  has a substantially cylindrical shape extending along the direction of the extending central axis Cs of the central axis Cs. In the present embodiment, the direction of the central axis Cs is the radial direction Dr, and is also the vane length direction. In a rotatable state, the shaft portion  42  is inserted into the insertion hole  51   h  formed in the frame  50 . 
     As shown in  FIG. 3 , a tip portion  42   s  of the shaft portion  42  protrudes outward in the radial direction Dr from the vane holder  51 . An end portion  65   a  of a link plate  65  is fixed to the tip portion  42   s  of the shaft portion  42  so that the end portion  65   a  is not rotatable around the central axis Cs. A drive pin  66  is connected to an end portion  65   b  of the link plate  65 . The drive pin  66  is disposed on the outer side in the radial direction Dr of the frame  50 , and is supported so as to be rotatable around the central axis of the drive pin  66  by a turning ring  67  disposed so as to be capable of turning in the circumferential direction of the frame  50 . The turning ring  67  is rotatable around a central axis Cf (refer to  FIG. 2 ) of the frame  50  by an actuator  26  (refer to  FIG. 1 ). If the turning ring  67  is turned around the central axis Cf by the actuator  26 , the link plate  65  oscillates around the shaft portion  42  as a center. In this manner, the shaft portion  42  is rotated around the central axis Cs. In this manner, an angle (opening degree) of the vane main body  41  is changed in the flow of the fluid G in the flow path  100  inside the frame  50 , and a flow rate of the fluid G passing through the gas inlet  23  is controlled. 
     As shown in  FIG. 4 , the bearing portion  60  is disposed inside the insertion hole  51   h  in order to support each of the movable vanes  40 . The bearing portion  60  supports the shaft portion  42  so as to be rotatable around the central axis Cs with respect to the insertion hole  51   h  formed in the frame  50 . The plurality of bearing portions  60  according to the present embodiment are disposed at an interval in the direction of the central axis Cs of the shaft portion  42 . The bearing portion  60  has a cylindrical shape. According to the present embodiment, as the bearing portion  60 , two of a first bearing portion  60 A and a second bearing portion  60 B are disposed therein. 
     The vane holder  51  supporting the shaft portion  42  so as to be rotatable around the central axis Cs includes a base portion  52 , a plurality of seal holding members  55 , an intermediate member  56 , and a seal pressure member  57 . 
     The base portion  52  is formed so as to protrude outward in the radial direction Dr from an outer peripheral surface  50   f  of the frame  50 . The base portion  52  has an outer peripheral recess portion (recess portion)  53  recessed inward in the radial direction Dr on an outer peripheral surface  52   f  of the base portion  52  facing outward in the radial direction Dr of the frame  50 . In addition, in the frame  50 , a portion where the base portion  52  is formed has an inner peripheral recess portion  54  recessed outward in the radial direction Dr of the frame  50  from an inner peripheral surface  50   g  thereof. The inner peripheral recess portion  54  accommodates a portion of the end portion  41   a  of the vane main body  41  of the movable vane  40 . 
     In addition, the base portion  52  has a base portion through-hole  52   h  extending along the radial direction Dr of the frame  50 . The base portion through-hole  52   h  penetrates a bottom surface  54   b  of an inner peripheral recess portion  54  and a bottom surface  53   b  of an outer peripheral recess portion  53 . The base portion through-hole  52   h  forms a portion of the insertion hole  51   h . The first bearing portion  60 A is fitted inward toward the outside in the radial direction Dr of the frame  50  with respect to the base portion through-hole  52   h.    
     According to the present embodiment, two seal holding members  55  are provided. The seal holding members  55  are accommodated inside the outer peripheral recess portion  53  of the base portion  52  in a stacked state along the direction of the central axis Cs. As shown in  FIG. 5 , the seal holding member  55  has a holding member through-hole  55   h  forming a portion of the insertion hole  51   h  in the central portion in the direction of the central axis Cs. In addition, the seal holding member  55  has an accommodation portion  58  which accommodates a first seal member  71  (to be described later). 
     The accommodation portion  58  is formed on a holding member first surface  55   f  side in the direction of the central axis Cs of the seal holding member  55 . The accommodation portion  58  has an annular shape continuous in the circumferential direction on the outer side in a hole diameter direction Ds of the holding member through-hole  55   h , and is formed to be recessed toward the holding member second surface  55   g  side in the direction of the central axis Cs. Here, the holding member first surface  55   f  is a surface facing outward in the radial direction Dr in the seal holding member  55 . In addition, the holding member second surface  55   g  is a surface facing inward in the radial direction Dr in the seal holding member  55 . The accommodation portion  58  has an inner peripheral side stepped portion  58   a  facing the inner peripheral side of the holding member through-hole  55   h  and an outer peripheral side stepped portion  58   b  which is recessed toward the holding member second surface  55   g  side and whose dimension is smaller than the inner peripheral side stepped portion  58   a . The outer peripheral side stepped portion  58   b  is formed to be continuous with the outer peripheral side of the inner peripheral side stepped portion  58   a.    
     In addition, on the holding member second surface  55   g  side, the seal holding member  55  has a holding member groove  59  which is continuous in the circumferential direction and which is recessed toward the holding member first surface  55   f  side. The holding member groove  59  is annularly formed on the outer side in the hole diameter direction Ds from the accommodation portion  58  when viewed in the direction of the central axis Cs. The holding member groove  59  accommodates a third seal member  79  (to be described later). 
     On the intermediate member second surface  56   b  side in the direction of the central axis Cs, the intermediate member  56  integrally has a flange portion  56   d  extending toward the outer peripheral side. In the intermediate member  56 , the flange portion  56   d  is inserted into the outer peripheral recess portion  53  of the base portion  52 . The intermediate member  56  is stacked on the outer side in the radial direction Dr with respect to the seal holding member  55 . Outer peripheral portions of the two seal holding members  55  and the intermediate member  56  are fastened and fixed to each other in the base portion  52  by using a bolt  61 . 
     Here, the intermediate member first surface  56   a  is a surface facing outward in the radial direction Dr in the intermediate member  56 . In addition, the intermediate member second surface  56   b  is a surface facing inward in the radial direction Dr in the intermediate member  56 . 
     On the intermediate member first surface  56   a  side in the direction of the central axis Cs, the intermediate member  56  has an intermediate recess portion  561  recessed toward the intermediate member second surface  56   b  in the direction of the central axis Cs. In addition, the intermediate member  56  has an intermediate member through-hole  56   h  penetrating the intermediate recess portion  561  and the intermediate member second surface  56   b  in the central portion in the hole diameter direction Ds. The intermediate member through-hole  56   h  forms a portion of the insertion hole  51   h.    
     The intermediate member  56  has a hole side recess portion  562  recessed outward in the hole diameter direction Ds of the intermediate member through-hole  56   h . The hole side recess portion  562  is continuous in the circumferential direction around the central axis Cs in the intermediate portion in the direction of the central axis Cs of the intermediate member through-hole  56   h.    
     The hole side recess portion  562  may not be formed in the intermediate member  56 , and a shaft side recess portion recessed inward in the hole diameter direction Ds may be formed on the outer peripheral surface  42   f  of the shaft portion  42 . Therefore, at least one of the hole side recess portion  562  and the shaft side recess portion may be formed so as to form a space for widening a space between the first seal member  71  and the second seal member  72 . 
     In addition, on the intermediate member second surface  56   b  side, the intermediate member  56  has an intermediate member groove  563  which is continuous in the circumferential direction and which is recessed toward the intermediate member first surface  56   a  side. The intermediate member groove  563  is annularly formed on the outer side in the hole diameter direction Ds from the accommodation portion  58  formed in the seal holding member  55  when viewed in the direction of the central axis Cs. The intermediate member groove  563  accommodates a third seal member  79  (to be described later). 
     The seal pressure member  57  is located on the outer side in the radial direction Dr with respect to the intermediate member  56 . The central portion of seal pressure member  57  has a through-hole  57   h  forming a portion of the insertion hole  51   h . The second bearing portion  60 B is fitted inward from the outer side in the radial direction Dr of the frame  50  with respect to the seal pressure member  57 . On the second surface  57   b  side in the direction of the central axis Cs, the seal pressure member  57  has an insertion cylinder portion  571  which is inserted into the intermediate recess portion  561  of the intermediate member  56 . The second seal member  72  located inside the intermediate recess portion  561  is interposed between the insertion cylinder portion  571  of the seal pressure member  57  and the bottom surface  561   b  of the intermediate recess portion  561 . 
     The seal portion  70  is located inside the insertion hole  51   h  of the above-described vane holder  51 . The seal portion  70  is located between the plurality of bearing portions  60  in the direction of the central axis Cs. The seal portion  70  seals a portion between the insertion hole  51   h  and the shaft portion  42 , thereby preventing the fluid G from flowing outward from the inner side of the frame  50 , that is, flowing out of the flow path  100 . The seal portion  70  according to the present embodiment is disposed between the first bearing portion  60 A and the second bearing portion  60 B. The seal portion  70  has the first seal member  71  and the second seal member  72  which are arranged at an interval in the direction of the central axis Cs. 
     The first seal member  71  is accommodated in the accommodation portion  58  of the seal holding member  55 . The first seal members  71  are respectively accommodated in the two seal holding members  55 . That is, the first seal members  71  are disposed in a double structure in the direction of the central axis Cs. 
     The first seal member  71  has an annular seal portion main body  73  to be accommodated in the inner peripheral side stepped portion  58   a  of the accommodation portion  58  and a lip portion  76  extending outward in the hole diameter direction Ds from the seal portion main body  73 . 
     The seal portion main body  73  is continuous in the circumferential direction on the outer side in the hole diameter direction Ds of the shaft portion  42 . The seal portion main body  73  includes an elastic ring portion  74  and a biasing member  75 . The lip portion  76  is accommodated in the outer peripheral side stepped portion  58   b.    
     The elastic ring portion  74  has an annular shape continuous in the circumferential direction on the outer side in the hole diameter direction Ds of the shaft portion  42 . The elastic ring portion  74  is made of an elastic material such as a rubber-based material. The elastic ring portion  74  has a ring groove  74   m  which is open inward in the radial direction Dr of the frame  50 . 
     The biasing member  75  is formed from a leaf spring material curved in an inverted U-shape which is open inward in the radial direction Dr. The biasing member  75  is accommodated inside the ring groove  74   m  of the elastic ring portion  74 . The biasing member  75  causes the inner peripheral surface  74   f  of the elastic ring portion  74  to be biased inward in the hole diameter direction Ds of the insertion hole  51   h.    
     The second seal member  72  is accommodated in the intermediate recess portion  561  of the intermediate member  56 . The second seal member  72  is located at a position farther from the vane main body  41  than the first seal member  71 . That is, the two first seal members  71  are arranged at a position closer to the vane main body  41  than the second seal member  72  in the insertion hole  51   h . The second seal member  72  includes a seal cap  77  and a seal ring  78 . 
     The seal cap  77  has a cap groove  77   m  which has an annular shape and which is open outward in the hole diameter direction Ds of the insertion hole  51   h . The seal ring  78  is made of a rubber-based material. The seal ring  78  is disposed inside the cap groove  77   m . The seal ring  78  causes the seal cap  77  to be biased inward in the hole diameter direction Ds of the insertion hole  51   h.    
     In this way, the first seal member  71  and the second seal member  72  have mutually different seal structures. In addition, the first seal member  71  located inward in the radial direction Dr from the second seal member  72  has sealing performance which is higher than that of the second seal member  72 . 
     The first seal member  71  and the second seal member  72  are not limited to an example where both of these have the mutually different seal structures. Both of these may have the same seal structure. 
     The seal portion  70  further includes the third seal member  79 . The third seal member  79  is an O-ring made of an annular rubber-based material. The third seal members  79  are respectively accommodated in the holding member groove  59  and the intermediate member groove  563 . The third seal member  79 A accommodated in the holding member groove  59  seals a portion between the seal holding member  55 A and the bottom surface  53   b  of the outer peripheral recess portion  53  of the base portion  52  facing the seal holding member  55 A. The third seal member  79 C accommodated in the intermediate member groove  563  seals a portion between the intermediate member  56  and the seal holding member  55 B. 
     In addition, the seal portion  70  includes a seal space  80  between the first seal member  71  and the second seal member  72 . The seal space  80  is formed between the first seal member  71  and the second seal member  72 . The seal space  80  is formed so that a cross-sectional area of a clearance between the insertion hole  51   h  and the shaft portion  42  is widened by the hole side recess portion  562 . 
     According to the inlet guide vane  24  and the centrifugal compressor system  1  of the above-described embodiment, the seal portion  70  located between the plurality of first bearing portions  60 A and the second bearing portion  60 B prevent the fluid G inside the flow path  100  from leaking outward after passing between the insertion hole  51   h  the shaft portion  42 . Only the fluid passing through the clearance between the first bearing portion  60 A and the second bearing portion  60 B and the outer peripheral surface of the shaft portion  42  arrives at the seal portion  70 . Therefore, the seal portion  70  is less likely to be exposed to the fluid, and is less likely to be affected by the fluid, compared to a case where the seal portion  70  is directly exposed to the fluid. Therefore, it is possible to continuously achieve the high sealing performance by preventing the seal portion  70  from being degraded. 
     In addition, the first bearing portion  60 A and the second bearing portion  60 B which have the cylindrical shape are disposed on both sides in the direction of the central axis Cs of the shaft portion  42  with respect to the seal portion  70 . Compared to a case of disposing a ball bearing, for example, instead of the first bearing portion  60 A and the second bearing portion  60 B, the clearance becomes smaller between the outer peripheral surface  42   f  of the shaft portion  42  and the first bearing portion  60 A and the second bearing portion  60 B. Therefore, only the fluid G passing through the clearance between the first bearing portion  60 A and the outer peripheral surface  42   f  of the shaft portion  42  arrives at the first seal member  71 . Accordingly, it is possible to effectively achieve the sealing performance in the first seal member  71 . In this way, it is possible to improve the sealing performance in the shaft portion  42  of the movable vane  40 . 
     In addition, the sealing performance can be improved by allowing the seal portion  70  to have a double configuration of the first seal member  71  and the second seal member  72 . Furthermore, the first seal members  71  are disposed in a double structure. Therefore, the sealing performance can be further improved. 
     In addition, the first seal member  71  and the second seal member  72  are caused to have the mutually different seal structures, thereby configuring the seal portion  70  having a plurality of sealing characteristics. As a result, the higher sealing performance is ensured. 
     In addition, the first seal member  71  has the sealing performance higher than that of the second seal member  72  located outward in the radial direction Dr which is away from the vane main body  41  with respect to the first seal member  71 . According to this configuration, the first seal member  71  can effectively prevent the fluid G from leaking out of the flow path  100  side. In addition, the second seal member  72  can function as a backup member for sealing the clearance against only the fluid G passing through the first seal member  71 . Therefore, even if the sealing performance of the second seal member  72  is suppressed, the sealing performance of the seal portion  70  can be ensured as a whole. As a result, cost for the second seal member  72  can be minimized. 
     In addition, in the first seal member  71 , the biasing member  75  causes the inner peripheral surface  74   f  of the elastic ring portion  74  to be biased inward in the hole diameter direction Ds. In this manner, it is possible to improve the sealing performance between the first seal member  71  and the shaft portion  42 . 
     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  24 B 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  60 A and the second bearing portion  60 B 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  70 B is disposed between the first bearing portion  60 A and the second bearing portion  60 B. A seal space  80 B is formed between the first seal member  71  and the second seal member  72  of the seal portion  70 B by a hole side recess portion  562  formed in the intermediate member  56 . 
     The seal portion  70 B includes a sensor  90  which detects that the fluid G inside the flow path  100  enters the seal space  80 B. The sensor  90  detects that the fluid G enters the seal space  80 B by detecting the pressure, the temperature, or the substances configuring the fluid G inside the seal space  80 B. 
     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  70 B 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  24 C 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  60 A and the second bearing portion  60 B 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  70 C is disposed between the first bearing portion  60 A and the second bearing portion  60 B. A seal space  80 C is formed between the first seal member  71  and the second seal member  72  of the seal portion  70 C 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  80 C of the clearance between the insertion hole  51   h  and the shaft portion  42 . 
     The sealing fluid supply unit  95  pressurizes the seal space  80 C by supplying the sealing fluid Gs. It is preferable that the pressure inside the pressurized seal space  80 C 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  80 C between the first seal member  71  and the second seal member  72  so as to pressurize the inside of the seal space  80 C. 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  80 C. 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 ,  24 B, and  24 C 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 ,  24 B,  24 C: 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 ,  55 A,  55 B: 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 
       60 A: first bearing portion 
       60 B: second bearing portion 
       61 : bolt 
       65 : link plate 
       65   a ,  65   b : end portion 
       66 : drive pin 
       67 : turning ring 
       70 ,  70 B,  70 C: 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 ,  79 A,  79 B,  79 C: third seal member 
       80 ,  80 B,  80 C: 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