Patent Publication Number: US-11649828-B2

Title: Rotary machine

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a rotary machine. 
     Priority is claimed on Japanese Patent Application No. 2021-028524, filed Feb. 25, 2021, the content of which is incorporated herein by reference. 
     Description of Related Art 
     For example, Patent Document 1 discloses a rotary machine in which an impeller as a rotary body is fixed to an end portion of a rotary shaft. The impeller is provided with a through hole that passes therethrough in a direction of an axis. 
     The impeller and the rotary shaft are integrally fixed to each other by fastening a bolt inserted into the through hole to the end portion of the rotary shaft. 
     SUMMARY OF THE INVENTION 
     By the way, when an impeller as the rotary body is rotated at high speed, the centrifugal load applied to the impeller also increases. In the rotary machine disclosed in the Patent Document 1, since a through hole passing through the impeller in a direction of an axis is formed, a strength of the impeller is reduced by the through hole. 
     On the other hand, the rotary body such as the impeller needs to be firmly fixed to the rotary shaft. 
     The present disclosure provides a rotary machine capable of improving a strength of the rotary body against the centrifugal load while firmly fixing the rotary body to the rotary shaft. 
     A rotary machine according to the present disclosure includes a rotary shaft that has a cylindrical shape extending in a direction of an axis and has end surfaces at both sides in the direction of the axis, a fastening bolt that extends in the direction of the axis in the rotary shaft and has a bolt body having fastening portions formed at both ends, a pair of rotary bodies each having a fastened portion disposed at both sides of the fastening bolt in the direction of the axis and to be fixed to the fastening portion at an end portion in the direction of the axis, and a contact surface in contact with one of the end surfaces of the rotary shaft, and a bolt extension mechanism that is configured to temporarily extend the bolt body in the direction of the axis. 
     According to the present disclosure, a strength of the rotary body against a centrifugal load can be improved while firmly fixing the rotary body to the rotary shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic side view of a rotary machine according to a first embodiment of the present disclosure. 
         FIG.  2    is a vertical cross-sectional view of a main part of the rotary machine according to the first embodiment of the present disclosure. 
         FIG.  3    is a vertical cross-sectional view of a main part of the rotary machine according to a second embodiment of the present disclosure. 
         FIG.  4    is a vertical cross-sectional view of a main part of the rotary machine according to the third embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     Hereinafter, a rotary machine according to an embodiment of the present invention will be described in detail with reference to  FIGS.  1  and  2   . 
     &lt;Outline Configuration of Geared Compressor&gt; 
     As shown in  FIG.  1   , a geared compressor  1  as a rotary machine has a rotary shaft  10 , radial bearings  20 , thrust bearings  30 , a first impeller  40 , a second impeller  60 , and a power transmission portion  80 . 
     The rotary shaft  10  extends about an axis O extending in a horizontal direction. 
     The radial bearings  20  rotatably support the rotary shaft  10  around the axis O. A pair of radial bearings  20  are provided so as to be separated from each other in a direction of the axis O (axial direction). Each of the pair of radial bearings  20  supports the rotary shaft  10  at a position close to an end portion of the rotary shaft  10  in the direction of the axis O. 
     The thrust bearings  30  support a load applied in the direction of the axis O of the rotary shaft  10 . A pair of thrust bearings  30  are provided between the pair of radial bearings  20  so as to be separated from each other in the direction of the axis O. 
     The first impeller  40  is integrally fixed to the rotary shaft  10  at the first side of the rotary shaft  10  in the direction of the axis O (a left side in  FIG.  1   ). The first impeller  40  has a first disk  50  and first blades  58 . 
     The first disk  50  has a disk shape centered on the axis O. A surface of the first disk  50  facing a first side in the direction of the axis O is curved so as to extend outward in a radial direction toward a second side in the direction of the axis O (a right side in  FIG.  1   ). 
     A plurality of the first blades  58  are provided on the surface of the first disk  50  facing the first side in the direction of the axis O at intervals in a circumferential direction. 
     The second impeller  60  is integrally fixed to the rotary shaft  10  at the second side of the rotary shaft  10  in the direction of the axis O. The second impeller  60  has a second disk  70  and second blades  78 . 
     The second disk  70  has a disk shape centered on the axis O. A surface of the second disk  70  facing the second side in the direction of the axis O is curved so as to extend outward in the radial direction toward the first side in the direction of the axis O. 
     A plurality of the second blades  78  are provided on the surface of the second disk  70  facing the second side in the direction of the axis O at intervals in the circumferential direction. 
     The power transmission portion  80  transmits a driving force applied from the outside to the rotary shaft  10  to rotate the rotary shaft  10 . The power transmission portion  80  has a pinion gear  81  and a large diameter gear  82 . 
     The pinion gear  81  is integrally fixed to the rotary shaft  10  between the pair of thrust bearings  30  on the rotary shaft  10 . Gear teeth are formed on an outer peripheral surface of the pinion gear  81 . 
     The large diameter gear  82  is a gear that is rotated by a driving force applied from the outside. Gear teeth on an outer peripheral surface of the large diameter gear  82  are engaged with the gear teeth of the pinion gear  81 . When the large diameter gear  82  is driven by a drive unit (not shown), the pinion gear  81  and the rotary shaft  10  integrally fixed to the pinion gear  81  rotate in connection therewith. Accordingly, the first impeller  40  and the second impeller  60  integrated with the rotary shaft  10  also rotate, and gas flowing into the first impeller  40  and the second impeller  60  from the direction of the axis O is pumped outward in the radial direction. 
     &lt;Fixing Structure to Rotary Shaft and Rotary Body&gt; 
     Hereinafter, the details of a fixing structure to the rotary shaft  10  and the first impeller  40  and the second impeller  60  will be described with reference to  FIG.  2   . In addition to the rotary shaft  10 , the first impeller  40 , and the second impeller  60  as a configuration related to the fixing structure, the geared compressor  1  further includes a fastening bolt  90  and a fluid pressure supply unit  120  as an example of a bolt extension mechanism. 
     &lt;Rotary Shaft&gt; 
     The rotary shaft  10  has a cylindrical shape centered on the axis O. That is, the rotary shaft  10  has a hollow structure having a through hole extending over both ends in the direction of the axis O to be open at both ends. The radial dimensions of an outer peripheral surface  11  and an inner peripheral surface  12  of the rotary shaft  10  are uniform. The rotary shaft  10  has a first end surface  13   a  and a second end surface  13   b  as a pair of end surfaces. The first end surface  13   a  is an end surface at the first side of the rotary shaft  10  in the direction of the axis O, and has a planar shape orthogonal to the axis O. The second end surface  13   b  is an end surface at the second side of the rotary shaft  10  in the direction of the axis O, and has a planar shape orthogonal to the axis O like the first end surface  13   a.    
     &lt;Fastening Bolt  90 &gt; 
     The fastening bolt  90  is provided inside the rotary shaft  10  that has a cylindrical shape. The fastening bolt  90  has a bolt body  91 , a first brim portion  100  and a second brim portion  110  as a pair of brim portions, and a first seal portion  102  and a second seal portion  112  as a pair of seal portions. 
     &lt;Bolt Body  91 &gt; 
     The bolt body  91  has a rod shape extending in the direction of the axis O with the axis O as the center in the rotary shaft  10 . A diameter of the bolt body  91  is smaller than an inner diameter of the rotary shaft  10 . Accordingly, an outer peripheral surface of the bolt body  91  and the inner peripheral surface  12  of the rotary shaft  10  are separated from each other. 
     A first fastening portion  92  and a second fastening portion  93  as a pair of fastening portions are provided at end portions of the bolt body  91  in the direction of the axis O. 
     The first fastening portion  92  is provided at one end portion of the bolt body  91  at the first side in the direction of the axis O. The first fastening portion  92  has a male screw formed on the outer peripheral surface of the bolt body  91 . The second fastening portion  93  is provided at an end portion of the bolt body  91  at the second side in the direction of the axis O. Similar to the first fastening portion, the second fastening portion  93  has a male screw formed on the outer peripheral surface of the bolt body  91 . In the present embodiment, the first fastening portion  92  and the second fastening portion  93  are positioned in the rotary shaft  10 . The first fastening portion  92  may protrude from the rotary shaft  10  to the first side in the direction of the axis O. The second fastening portion  93  may protrude from the rotary shaft  10  to the second side in the direction of the axis O. 
     &lt;Brim Portion&gt; 
     The first brim portion  100  and the second brim portion  110  have a disk shape formed so as to protrude outward in the radial direction from the outer peripheral surface of the bolt body  91 . The first brim portion  100  and the second brim portion  110  are provided between the first fastening portion  92  and the second fastening portion  93  to be separated from each other in the direction of the axis O. 
     The first brim portion  100  is provided at a portion of the bolt body  91  that is closer to the first side in the direction of the axis O. The second brim portion  110  is provided at a portion of the bolt body  91  that is closer to the second side in the direction of the axis O. 
     Outer peripheral surfaces of the first brim portion  100  and the second brim portion  110  each have a cylindrical surface shape. Outer diameters of the outer peripheral surfaces of the first brim portion  100  and the second brim portion  110  have the same dimensions as an inner diameter of the inner peripheral surface  12  of the rotary shaft  10 , or have slightly smaller dimensions than the inner diameter of the inner peripheral surface  12  of the rotary shaft  10 . Accordingly, the outer peripheral surfaces of the first brim portion  100  and the second brim portion  110  are slidable in the direction of the axis O with respect to the inner peripheral surface  12  of the rotary shaft  10 . 
     A surface of the first brim portion  100  facing the second side in the direction of the axis O is a first pressure receiving surface  101  having a planar shape orthogonal to the axis O. A surface of the second brim portion  110  facing the first side in the direction of the axis O is a second pressure receiving surface  111  having a planar shape orthogonal to the axis O. The first pressure receiving surface  101  and the second pressure receiving surface  111  face each other in the direction of the axis O. 
     &lt;Seal Portion&gt; 
     The first seal portion  102  is provided on an outer peripheral surface of the first brim portion  100 . The second seal portion  112  is provided on an outer peripheral surface of the second brim portion  110 . The first seal portion  102  and the second seal portion  112  are seal rings such as an O-ring and a C-ring provided in a circumferential direction. The first seal portion  102  and the second seal portion  112  are slidable in the direction of the axis O with respect to the inner peripheral surface  12  of the rotary shaft  10 . 
     The first seal portion  102  and the second seal portion  112  seal a clearance between the outer peripheral surfaces of the first brim portion  100  and the second brim portion  110  and the inner peripheral surface  12  of the rotary shaft  10  in a liquid-tight manner over an entire circumferential direction. Accordingly, an internal space R that is liquid-tightly separated from the other space in the rotary shaft  10  is formed as a partition between the first brim portion  100  and the second brim portion  110  in the rotary shaft  10 . 
     Here, a fluid pressure supply hole  14  passing through an inside and an outside of the rotary shaft  10  is provided at a position in the direction of the axis O corresponding to the internal space R in the rotary shaft  10 . The internal space R communicates with the outside of the rotary shaft  10  via the fluid pressure supply hole  14 . 
     &lt;First Impeller&gt; 
     A first convex portion  51  protruding to the second side in the direction of the axis O with the axis O as the center is provided on a surface of the first disk  50  of the first impeller  40  facing the second side in the direction of the axis O. The first convex portion  51  has a first large diameter portion  52 , which is a base end portion at the first side in the direction of the axis O, and a first small diameter portion  53  having a diameter smaller than that of the first large diameter portion  52 , which is a tip portion at the second side in the direction of the axis O. The first large diameter portion  52  and the first small diameter portion  53  are each formed in a cylindrical shape having a different diameter from each other while being centered on the axis O. 
     A first fastened portion  54  is provided on a tip surface of the first small diameter portion  53 , which is an end portion of the first impeller  40  at the second side in the direction of the axis O. The first fastened portion  54  is a bolt fixing hole that is recessed at the first side in the direction of the axis O with the axis O as the center. A female screw to be fastened to the male screw of the first fastening portion  92  of the bolt body  91  is formed on an inner peripheral surface of the first fastened portion  54 . 
     The first fastened portion  54  does not pass through the first impeller  40  in the direction of the axis O. Therefore, the first impeller  40  has a solid structure filled inside. 
     A position of a bottom portion of the first fastened portion  54  in the direction of the axis O has a formation range of the first small diameter portion  53 . The position of the bottom portion of the first fastened portion  54  in the direction of the axis O may also have a formation range of the first large diameter portion  52 , that is, a formation range of the first convex portion  51 . Furthermore, the position of the bottom portion of the first fastened portion  54  in the direction of the axis O may be, for example, a position at the second side of the first disk  50  in the direction of the axis O with respect to the outermost diameter portion. 
     A stepped surface between the first large diameter portion  52  and the first small diameter portion  53  in the first convex portion  51  is a first contact surface  55  having a planar shape that faces the second side in the direction of the axis O and is orthogonal to the axis O. The first contact surface  55  faces the first end surface  13   a  of the rotary shaft  10  in the direction of the axis O. In a state where the first impeller  40  and the rotary shaft  10  are fixed to and integrated with each other, the first contact surface  55  of the first impeller  40  and the first end surface  13   a  of the rotary shaft  10  are firmly in close contact with each other. 
     &lt;Second Impeller  60 &gt; 
     A second convex portion  71  protruding from the axis O to the first side in the direction of the axis O with the axis O as the center is provided on a surface of the second disk  70  of the second impeller  60  facing the first side in the direction of the axis O. The second convex portion  71  has a second large diameter portion  72 , which is a base end portion at the second side in the direction of the axis O, and a second small diameter portion  73  having a diameter smaller than that of the second large diameter portion  72 , which is a tip portion at the first side in the direction of the axis O. The second large diameter portion  72  and the second small diameter portion  73  are each formed in a cylindrical shape having a different diameter from each other while being centered on the axis O. 
     A second fastened portion  74  is provided on a tip surface of the second small diameter portion  73 , which is an end portion of the second impeller  60  at the first side in the direction of the axis O. The second fastened portion  74  is a bolt fixing hole that is recessed at the second side in the direction of the axis O with the axis O as the center. A female screw to be fastened to the male screw of the second fastening portion  93  of the bolt body  91  is formed on an inner peripheral surface of the second fastened portion  74 . 
     The second fastened portion  74  does not pass through the second impeller  60  in the direction of the axis O. Therefore, the second impeller  60  has a solid structure filled inside. 
     A position of a bottom portion of the second fastened portion  74  in the direction of the axis O has a formation range of the second small diameter portion  73 . The position of the bottom portion of the second fastened portion  74  in the direction of the axis O may also have a formation range of the second large diameter portion  72 , that is, a formation range of the second convex portion  71 . Furthermore, the position of the bottom portion of the second fastened portion  74  in the direction of the axis O may be, for example, a position at the first side of the second disk  70  in the direction of the axis O with respect to the outermost diameter portion. 
     A stepped surface between the second large diameter portion  72  and the second small diameter portion  73  in the second convex portion  71  is a second contact surface  75  having a planar shape that faces the first side in the direction of the axis O and is orthogonal to the axis O. The second contact surface  75  faces the second end surface  13   b  of the rotary shaft  10  in the direction of the axis O. In a state where the second impeller  60  and the rotary shaft  10  are fixed to and integrated with each other, the second contact surface  75  of the second impeller  60  and the second end surface  13   b  of the rotary shaft  10  are firmly in close contact with each other. 
     &lt;Fluid Pressure Supply Unit&gt; 
     The fluid pressure supply unit  120  can supply fluid pressure to the internal space R in the rotary shaft  10  via the fluid pressure supply hole  14 . The fluid pressure supply unit  120  supplies hydraulic oil to the internal space R by, for example, an oil pressure pump. Accordingly, when the internal space R is filled with the hydraulic oil, oil pressure (fluid pressure) by the hydraulic oil acts on the first pressure receiving surface  101  of the first brim portion  100  and the second pressure receiving surface  111  of the second brim portion  110 . When the supply of the hydraulic oil by the fluid pressure supply unit  120  is stopped, the oil pressure acting on the first pressure receiving surface  101  and the second pressure receiving surface  111  disappears. That is, the fluid pressure supply unit  120  is configured to switch between the supply and stoppage of the oil pressure to the internal space R. 
     Furthermore, the fluid pressure supply unit  120  may also be configured to supply other liquids, gases, or the like instead of being configured to supply the oil pressure. 
     &lt;Operational Effects&gt; 
     Next, in the geared compressor  1  having the above configuration, a procedure for fixedly integrating the rotary shaft  10  into the first impeller  40  and the second impeller  60  will be described. 
     First, in a state where the fastening bolt  90  to which the first impeller  40  and the second impeller  60  are not fixed is disposed in the rotary shaft  10 , hydraulic oil is supplied to the internal space R via the fluid pressure supply hole  14  by the fluid pressure supply unit  120 . Accordingly, oil pressure by the hydraulic oil acts on the first pressure receiving surface  101  of the first brim portion  100  and the second pressure receiving surface  111  of the second brim portion  110  in the fastening bolt  90 . That is, an external force is applied to the first pressure receiving surface  101  toward the first side in the direction of the axis O, and an external force is applied to the second pressure receiving surface  111  toward the second side in the direction of the axis O. Accordingly, external forces that tend to separate from each other in the direction of the axis O are applied to the first brim portion  100  and the second brim portion  110 . 
     Then, the bolt body  91  integrated with the first brim portion  100  and the second brim portion  110  is pulled to the first side and the second side in the direction of the axis O in association with a separation movement between the first brim portion  100  and the second brim portion  110 . Accordingly, the bolt body  91  is temporarily extended in the direction of the axis O. At this time, the first fastening portion  92  of the bolt body  91  is in a state of being positioned at the first side of the axis O direction compared to the initial position, and the second fastening portion  93  is in a state of being positioned at the second side of the axis O direction compared to the initial position. 
     In this state, the first impeller  40  and the second impeller  60  are attached and fixed to the fastening bolt  90 . That is, the first fastened portion  54  of the first impeller  40  is fastened to the first fastening portion  92  of the bolt body  91 . Moreover, the second impeller  60  is fastened to the second fastening portion  93  of the bolt body  91 . Accordingly, the first impeller  40  and the second impeller  60  are fixed to and integrated with the fastening bolt  90 . In a state where the first impeller  40  and the second impeller  60  are fastened to the bolt body  91  in this manner, the first contact surface  55  of the first impeller  40  and the first end surface  13   a  of the rotary shaft  10  are separated from each other, and the second contact surface  75  of the second impeller  60  and the second end surface  13   b  of the rotary shaft  10  are separated from each other. 
     Then, when the supply of hydraulic oil by the fluid pressure supply unit  120  is stopped in the above state, an action of the oil pressure on the first pressure receiving surface  101  of the first brim portion  100  and the second pressure receiving surface  111  of the second brim portion  110  is released, and as a result, the bolt body  91  pulled by the first brim portion  100  and the second-brim portion  110  tends to return to the original dimensions. As a result, the extension of the bolt body  91  is released. At the same time, the first contact surface  55  of the first impeller  40  and the first end surface  13   a  of the rotary shaft  10 , the second contact surface  75  of the second impeller  60  and the second end surface  13   b  of the rotary shaft  10 , which had been separated from each other until then, come into close contact with each other. Accordingly, the rotary shaft  10 , and the first impeller  40  and the second impeller  60  are firmly fixed and integrated via surface pressure at contact points with each other. A torque of the rotary shaft  10  is reliably transmitted to the first impeller  40  and the second impeller  60  via a frictional force due to the surface pressure. 
     According to the present embodiment as described above, the first impeller  40  and the second impeller  60  are fastened to the bolt body  91  in a state where the bolt body  91  is extended in the direction of the axis O by the fluid pressure supply unit  120  as a bolt extension mechanism. Then, when the extension of the bolt body  91  by the fluid pressure supply unit  120  is released later, the bolt body  91  returns to the original dimensions, and the first impeller  40  and the second impeller  60  come into close contact with the rotary shaft  10 . Accordingly, the rotary body and the rotary shaft  10  can be firmly fixed to and integrated with each other. 
     In addition, for the fastening of the first impeller  40  and the second impeller  60  to the bolt body  91 , since the bolt body  91  is in an extended state, a fastening work can be performed in a state where each of the first fastening portion  92  and the second fastening portion  93  of the bolt body  91  is easily accessed from the outside. Accordingly, the first impeller  40  and the second impeller  60  can be easily attached to the bolt body  91 . 
     Moreover, since the end portions of the first impeller  40  and the second impeller  60  are fixed to the bolt body  91 , it is not necessary to provide through holes or the like that pass through the first impeller  40  and the second impeller  60 . Therefore, the strengths of the first impeller  40  and the second impeller  60  can be ensured. Therefore, it is possible to sufficiently withstand a centrifugal stress when the geared compressor  1  operates at high speed. 
     Further, since the extension of the bolt body  91  is performed by the fluid pressure supply unit  120 , it is not necessary to provide a separate device in a narrow internal space R in the rotary shaft  10 . Therefore, it is not necessary to perform complicated work when extending the bolt body  91 . Consequently, the first impeller  40  and the second impeller  60  can be easily fixed to the rotary shaft  10 . 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described with reference to  FIG.  3   . In  FIG.  3   , the same elements as those in  FIG.  2    are designated by the same reference numerals, and detailed description thereof will be omitted. 
     Whereas the bolt extension mechanism in the first embodiment is the fluid pressure supply unit  120 , the present embodiment includes an extensible portion  200  as the bolt extension mechanism. 
     The extensible portion  200  is provided in the internal space R of the rotary shaft  10 . The extensible portion  200  is a cylinder rod mechanism having a tubular cylinder  201  extending in the direction of the axis O and a rod  202  capable of being retractable from the cylinder  201  in the direction of the axis O. In the present embodiment, an end portion of the cylinder  201  at the second side in the direction of the axis O is in contact with the second pressure receiving surface  111 , and an end portion of the rod  202  protruding from the cylinder  201  to the first side in the direction of the axis O is in contact with the first pressure receiving surface  101 . 
     The rod  202  is freely retractable in the direction of the axis O by fluid pressure supplied to the cylinder  201  from the outside or an actuator provided in the cylinder  201 . Accordingly, when the rod  202  is advanced from the cylinder  201 , the dimension of the extensible portion  200  in the direction of the axis O becomes longer, and as a result, the first brim portion  100  and the second brim portion  110  can separated from each other to extend the bolt body  91 . Therefore, the same operational effects as those of the first embodiment can be obtained. 
     Furthermore, a configuration other than the cylinder rod mechanism may be adopted for the extensible portion  200 , and for example, a linear motion mechanism including a ball screw or the like may be adopted. 
     Third Embodiment 
     Next, a third embodiment of the present invention will be described with reference to  FIG.  4   . In  FIG.  4   , the same elements as those in  FIG.  2    are designated by the same reference numerals, and detailed description thereof will be omitted. 
     Whereas the bolt extension mechanism in the first embodiment is the fluid pressure supply unit  120 , the present embodiment includes a heating unit  300  as the bolt extension mechanism. 
     The heating unit  300  has a structure capable of heating the bolt body  91 . For the heating unit  300 , for example, as shown in  FIG.  4   , a heating wire wound around the bolt body  91  can be adopted. By energizing the heating wire from the outside, the heating wire generates heat due to Joule heat. Accordingly, when the bolt body  91  around which the heating wire is wound is heated, the bolt body  91  thermally expands to extend in the direction of the axis O. Consequently, the same operational effects as those of the first and second embodiments can be obtained. 
     Furthermore, in addition to the heating wire, various configurations such as other heat sources and an induction heating device may be adopted for the heating unit  300 . 
     Other Embodiments 
     While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention. Accordingly, the invention is not to be considered as being limited by the foregoing description and is only limited by the scope of the appended claims. 
     For example, in the embodiments, an example in which the first impeller  40  and the second impeller  60  are adopted as rotary bodies has been described, but the present invention is not limited thereto. One of a pair of rotary bodies may be a counterweight. This also produces the same operational effects. 
     Moreover, in the embodiments, an example in which the bolt body  91  of the fastening bolt  90  is extended, and then both the first impeller  40  and the second impeller  60  are attached thereto has been described, but for example, one rotary body may be attached to the bolt body  91  before the bolt body  91  is extended. In this case, the bolt body  91  is extended in a state where one rotary body is attached to the bolt body  91 , and the other rotary body is attached to the bolt body  91 . Thus, the other rotary body can be easily attached thereto, and the same operational effects as those of the embodiments can be obtained. 
     Further, in the embodiments, an example in which the present invention is applied to the geared compressor  1  has been described, but the present invention may also be applied to a compressor having another configuration or another rotary machine. 
     &lt;Supplement&gt; 
     A rotary machine disclosed in each embodiment is understood as follows, for example. 
     (1) According to a first aspect, the rotary machine includes the rotary shaft  10  that has a cylindrical shape extending in a direction of the axis O and has end surfaces at both sides in the direction of the axis O, the fastening bolt  90  that has the bolt body  91  extending in the direction of the axis O in the rotary shaft  10  and having fastening portions formed at both ends, the first impeller  40  and the second impeller  60  each having the first fastened portion  54  disposed at both sides of the fastening bolt  90  in the direction of the axis O and the second fastened portion  74  to be fixed to the first fastening portion  92  and the second fastening portion  93  at an end portion in the direction of the axis O, and a contact surface in contact with one of the end surfaces of the rotary shaft  10 , and a bolt extension mechanism that is configured to temporarily extend the bolt body  91  in the direction of the axis O. 
     According to the above configuration, the first fastened portion  54  of the first impeller  40  and the second fastened portion  74  of the second impeller  60  are attached to the first fastening portion  92  and the second fastening portion  93  of the bolt body  91  in a state where the bolt body  91  is extended in the direction of the axis O by the bolt extension mechanism. Then, when the extension of the bolt body  91  by the bolt extension mechanism is released later, the bolt body  91  returns to the original dimensions, and the first contact surface  55  of the first impeller  40  and the second contact surface  75  of the second impeller  60  come into contact with the end surfaces of the rotary shaft  10 . Accordingly, the first impeller  40 , the second impeller  60  and the rotary shaft  10  are firmly in close contact with each other, and the first impeller  40 , the second impeller  60  and the rotary shaft  10  are integrally fixed to each other. 
     Further, since the end portions of the first impeller  40  and the second impeller  60  are fixed to the bolt body  91 , it is not necessary to provide through holes or the like in the first impeller  40  and the second impeller  60 . Therefore, the strengths of the first impeller  40  and the second impeller  60  can be ensured. 
     (2) According a second aspect, in the rotary machine according to the first aspect, the fastening bolt  90  further has a pair of the first brim portion  100  and the second brim portion  110  disposed to be separated from each other in the direction of the axis O to protrude from an outer peripheral surface of the bolt body  91 , and slidably contacting the inner peripheral surface  12  of the rotary shaft  10  in the direction of the axis O, and the bolt extension mechanism is configured to apply an external force to the first brim portion  100  and the second brim portion  110  such that the first brim portion  100  and the second brim portion  110  are separated from each other in the direction of the axis O. 
     The bolt body  91  integrally fixed to the first brim portion  100  and the second brim portion  110  can be extended in the direction of the axis O by separating those brim portions from each other in the direction of the axis O. 
     (3) According to a third aspect, in the rotary machine according to the second aspect, the bolt extension mechanism is the fluid pressure supply unit  120  that is configured to supply fluid pressure to a space partitioned by the pair of brim portions in the rotary shaft  10 . 
     Accordingly, the first brim portion  100  and the second brim portion  110  can be easily separated from each other in a narrow space provided with the first brim portion  100  and the second brim portion  110  in the rotary shaft  10 . 
     (4) According to a fourth aspect, in the rotary machine according to the second aspect, the bolt extension mechanism is the extensible portion  200  disposed in the internal space R partitioned by the first brim portion  100  and the second brim portion  110  in the rotary shaft  10  to separate a pair of the first brim portion  100  and the second brim portion  110  by extending in the direction of the axis O. 
     Accordingly, the first brim portion  100  and the second brim portion  110  can be easily separated from each other. 
     (5) According to a fifth aspect, in the rotary machine according to the first aspect, the bolt extension mechanism is the heating unit  300  disposed in the rotary shaft  10  to heat the bolt body  91 . 
     The bolt body  91  can be heated and thermally extended by the heating unit  300  to temporarily extend the bolt body  91 . 
     (6) According to a sixth aspect, in the rotary machine according to any one of the first to fifth aspects, the first impeller  40  and the second impeller  60  have a solid structure. 
     Accordingly, a strength of the rotary body against a centrifugal load can be ensured. 
     EXPLANATION OF REFERENCES 
     
         
           1  Geared compressor 
           10  Rotary shaft 
           11  Outer peripheral surface 
           12  Inner peripheral surface 
           13   a  First end surface 
           13   b  Second end surface 
           14  Fluid pressure supply hole 
           20  Radial bearing 
           30  Thrust bearing 
           40  First impeller (rotary body) 
           50  First disk 
           51  First convex portion 
           52  First large diameter portion 
           53  First small diameter portion 
           54  First fastened portion (fastened portion) 
           55  First contact surface (contact surface) 
           58  First blade 
           60  Second impeller (rotary body) 
           70  Second disk 
           71  Second convex portion 
           72  Second large diameter portion 
           73  Second small diameter portion 
           74  Second fastened portion (fastened portion) 
           75  Second contact surface (contact surface) 
           78  Second blade 
           80  Power transmission portion 
           81  Pinion gear 
           82  Large diameter gear 
           90  Fastening bolt 
           91  Bolt body 
           92  First fastening portion (fastening portion) 
           93  Second fastening portion (fastening portion) 
           100  First brim portion 
           101  First pressure receiving surface 
           102  First seal portion 
           110  Second brim portion 
           111  Second pressure receiving surface 
           112  Second seal portion 
           120  Fluid pressure supply unit (bolt extension mechanism) 
           200  Extensible portion (bolt extension mechanism) 
           201  Cylinder 
           202  Rod 
           300  Heating unit (bolt extension mechanism) 
         R Internal space 
         O Axis