JP5556414B2 - Cryogenic rotating machine - Google Patents

Description

  The present invention relates to a cryogenic rotating machine that sends a cryogenic refrigerant such as liquid nitrogen, liquid helium, and liquid hydrogen, and in particular, a stationary flow path including an inlet / outlet pipe for a cryogenic refrigerant is disposed in a vacuum vessel, and an impeller It is related with the cryogenic rotary machine which can remove the drive device containing this outside a vacuum vessel.

  Cryogenic rotating machines, for example, compressors and pumps for sending cryogenic refrigerants used for cooling superconducting magnets used in fusion reactors and accelerators, slowing down neutrons generated by atomic collisions, etc. A rotating machine such as a turbine. Here, the cryogenic temperature generally means a temperature obtained by using boiling under reduced pressure such as liquid helium and dilution refrigeration. Specifically, the saturation temperature at atmospheric pressure is 4K for liquid helium, 20K for hydrogen gas, and 80K for nitrogen gas, from which the temperature lower than the saturation temperature obtained by decompressing each refrigerant is extremely low. Equivalent to. The cryogenic refrigerant means a cryogenic gas or liquid, and includes, for example, liquid nitrogen, liquid helium, liquid hydrogen, and their vaporized gases. In such a cryogenic rotating machine, generally, an impeller side that imparts kinetic energy to a cryogenic refrigerant is arranged in a vacuum container that is insulated and cooled, and a driving device side that rotates the impeller is arranged outside the vacuum container (for example, a patent) Reference 1 and Patent Document 2). That is, the impeller side is disposed in a low-temperature refrigerant atmosphere, and the drive device side is disposed in a normal-temperature refrigerant atmosphere. Therefore, in order to maintain or improve the performance and efficiency of the cryogenic rotating machine, it is important to insulate between the impeller side and the drive device side to reduce the amount of heat penetration into the low temperature side.

  The cryogenic rotating machine described in Patent Document 1 operates an impeller provided at one end of a rotating shaft in a cryogenic region and holds a bearing portion supporting the rotating shaft in a state higher than the liquid nitrogen temperature level. A cryogenic rotating machine, in which an impeller, a heat insulating material inserted between a back surface portion of the impeller and a bearing portion, and a part of a rotating shaft are housed in a casing, and a part of the heat insulating material is a casing. A cooling gas flow path for cooling the heat insulating material and the casing is formed by supplying a fluid of the same quality as the working fluid cooled to the liquid nitrogen temperature level. For the bearing portion, for example, a non-contact type such as a dynamic pressure type gas bearing or a magnetic bearing is used.

JP-A-6-193598

  However, in the cryogenic rotating machine described in Patent Document 1, due to the nature of rotating the rotating shaft, a minute gap is inevitably formed between the heat insulating material and the rotating shaft, and the drive device side and the impeller side are It is difficult to keep the pressure in the space constant, and a minute pressure change occurs. Therefore, gas is generated between the impeller side and the drive device side in an attempt to make the pressure on the drive device side and the impeller side uniform. In particular, when a non-contact bearing is used for the bearing portion, gas ventilation is more likely to occur.

  More specifically, when the pressure on the impeller side (low temperature side) is higher than the pressure on the drive device side (room temperature side), the low temperature gas on the impeller side passes between the heat insulating material and the rotating shaft, and the drive device It flows into the side (room temperature side) and acts to make the pressure uniform. On the contrary, when the pressure on the drive unit side (room temperature side) is higher than the pressure on the impeller side (low temperature side), the room temperature gas on the drive unit side passes between the heat insulating material and the rotating shaft, and the impeller side (low temperature) ) And acts so that the pressure becomes uniform. Such an action occurs alternately, and gas reciprocation occurs between the driving device side and the impeller side.

  And when low temperature gas flows in into the drive device side, the device of the drive device side which is normal temperature may be cooled. For example, when the O-ring on the driving device side is cooled, the sealing performance of the O-ring may be reduced, which may cause leakage of cryogenic gas. Moreover, the inflow of the low-temperature gas to the driving device side also causes a decrease in the performance of the entire driving device.

  The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a cryogenic rotating machine that suppresses reciprocation of gas ventilation between an impeller side and a driving device side.

According to the present invention, in the cryogenic rotating machine in which the impeller side that imparts kinetic energy to the cryogenic refrigerant is disposed in a thermally insulated vacuum vessel, and the drive device side that rotationally drives the impeller is disposed outside the vacuum vessel, A rotating shaft that transmits the rotation of the driving device to the impeller, a bearing that supports the rotating shaft, a casing that houses the impeller and is fixed to the vacuum vessel, a housing that houses the driving device, and a rear surface of the casing A housing disposed in the housing, and the housing has a working space formed at a rear side of the drive device, and the filler includes the work There is provided a cryogenic rotating machine characterized in that it is disposed in a working space .

  The filler may be a member that reduces the volume of the space occupied by the gas in the casing, may be made of metal or ceramics, or may be a plurality of spheres or blocks.

  A heat insulating material disposed between the casing and the rotating shaft and between the impeller and the bearing, and maintaining the gap between the heat insulating material, the casing, and the rotating shaft; The volume of can be increased.

  The bearing may not have an opening other than the opening through which the rotating shaft or the fixed member is inserted.

  According to the cryogenic rotary machine according to the present invention described above, the volume occupied by the gas in the housing can be reduced by arranging the filler in the housing, and reciprocating between the drive device side and the impeller side. The total amount of gas flowing can be reduced. Therefore, the reciprocation of gas ventilation between the impeller side and the drive device side can be suppressed.

1 is an overall configuration diagram of a cryogenic rotary machine according to a first embodiment of the present invention. It is a whole block diagram which shows the state before filling with a filler. It is a figure for demonstrating the flow of the gas produced between the drive device side and the impeller side, (a) shows a comparative example (prior art), (b) shows 1st embodiment shown in FIG. ing. It is a figure which shows the material characteristic of helium gas, hydrogen gas, and nitrogen gas. It is an enlarged view of the housing periphery which shows other embodiment of the cryogenic rotary machine which concerns on this invention, (a) is 2nd embodiment, (b) is 3rd embodiment, (c) is 4th embodiment. , Shows. It is an enlarged view of a heat insulating material periphery which shows other embodiment of the cryogenic rotary machine which concerns on this invention, (a) has shown 5th embodiment, (b) has shown 6th embodiment.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is an overall configuration diagram of the cryogenic rotating machine according to the embodiment of the present invention. Moreover, FIG. 2 is a whole block diagram which shows the state before filling with a filler. FIGS. 3A and 3B are diagrams for explaining a gas flow generated between the driving device side and the impeller side. FIG. 3A is a comparative example (prior art), and FIG. 3B is a first embodiment shown in FIG. Form. 1 to 3, the illustration of the vacuum vessel is omitted.

  The cryogenic rotating machine 1 according to the first embodiment of the present invention, as shown in FIGS. 1 and 2, is disposed in a vacuum container in which the impeller 2 side that imparts kinetic energy to the cryogenic refrigerant is insulated and kept cool. A cryogenic rotary machine in which the drive device 3 side that rotates the impeller 2 is disposed outside the vacuum vessel, and includes a rotary shaft 4 that transmits the rotation of the drive device 3 to the impeller 2, and a journal bearing 5 that supports the rotary shaft 4. A casing 6 that houses the impeller 2 and is fixed to the vacuum vessel, a housing 7 that houses the driving device 3 and is disposed on the back surface of the casing 6, and a filler 8 that is disposed in the housing 7. Have.

  As shown in FIG. 1, the impeller 2 is connected to the tip of the rotating shaft 4 and is accommodated in the casing 6. A cryogenic refrigerant suction port 61 is formed on the upstream side of the impeller 2 on the concentric shaft, and a cryogenic refrigerant to which kinetic energy is imparted by centrifugal force is sent to the radial outer periphery of the impeller 2. A scroll portion 62 is formed. The scroll portion 62 communicates with an outlet pipe 63 connected to the casing 6. Further, the suction port 61 and the outlet pipe 63 constitute a stationary flow path disposed in the vacuum vessel.

  The driving device 3 is, for example, a non-contact type motor that includes a rotor 31 and a stator 32. The rotor 31 and the stator 32 are configured by, for example, an electromagnet, a permanent magnet, or the like. The rotor 31 is disposed on the rotating shaft 4 and the stator 32 is disposed on the housing 7. The rotor 31 generates a rotational moment by the interaction with the stator 32 and is rotationally driven together with the rotating shaft 4.

  The rotating shaft 4 includes a pair of journal bearings 5 and 9 disposed so as to sandwich the driving device 3, a thrust bearing 10 disposed on the back surface of the journal bearing 5, and an upper bearing 11 disposed on the rear end portion. , Is supported by. For example, magnetic bearings are employed as these bearings, and the rotating shaft 4 is supported in a non-contact state. Moreover, the part located between the impeller 2 of the rotating shaft 4 and the journal bearing 5 is formed in a thin hollow cylindrical shape so that heat transfer between the impeller 2 side and the drive device 3 side is difficult. It is configured.

  The journal bearing 5 has a substantially disk shape having an opening 51 through which the rotary shaft 4 is inserted at the center. Further, a recess 52 that accommodates a part of the heat insulating material 12 may be formed on the outer periphery of the opening 51. The journal bearing 5 is sandwiched between the casing 6 and the housing 7 as shown in FIG. The journal bearing 5 is formed so as not to have an opening other than the opening 51 through which the rotary shaft 4 is inserted or the opening (not shown) through which the fixing member (not shown) is inserted. Here, the fixing member means a fastening member such as a bolt for fixing the journal bearing 5 to the housing 7 or the casing 6. The other journal bearing 9 is inserted into the rear end side of the rotating shaft 4 and is fixed to the housing 7.

  As shown in FIG. 1, the casing 6 includes a main body 6 a having an opening 64 that accommodates part of the impeller 2 and the rotating shaft 4, and an enlarged diameter portion 6 b formed on the outer periphery of the main body 6 a. Have The main body 6 a is formed with the above-described suction port 61 and scroll portion 62 so as to communicate with the opening 64. Moreover, the part which accommodates the rotating shaft 4 of the main-body part 6a is formed in the thin hollow cylindrical shape, and it is comprised so that it may become difficult to transfer heat between the impeller 2 side and the drive device 3 side. Further, a recess 65 for accommodating the journal bearing 5 may be formed on the outer periphery of the opening 64 of the main body 6a on the drive device 3 side. Moreover, the enlarged diameter part 6b is fixed to the wall surface of the vacuum vessel which is not illustrated. That is, the casing 6 is inserted from the opening formed on the wall surface of the vacuum vessel on the impeller 2 side of the main body 6a, and the enlarged diameter portion 6b is disposed on the wall surface of the vacuum vessel so as to cover the opening, and is fixed from the outside. It is comprised so that.

  An annular groove 66 is formed along the outer periphery of the journal bearing 5 on the outer side of the vacuum vessel of the enlarged diameter portion 6 b of the casing 6, and an O-ring 67 is fitted in the annular groove 66. The O-ring 67 is sandwiched between the end surface of the housing 7 and the enlarged diameter portion 6 b of the casing 6, and seals the coupling surface between the housing 7 and the casing 6.

  The housing 7 accommodates the driving device 3, journal bearings 5, 9, thrust bearing 10, and upper bearing 11 and is disposed on the back surface of the casing 6. Specifically, the casing 7 has a cylindrical member 72 that forms a housing space for the drive device 3, a lid member 73 that seals the opening of the cylindrical member 72, and a cylinder that faces the lid member 73. An annular groove 74 formed in the annular member 72, and an O-ring 75 fitted in the annular groove 74. Note that the driving device 3 including the casing 6 and the impeller 2 disposed inside the housing 7 is configured to be removable from the vacuum container through the opening of the housing 7 during maintenance or the like.

  The cylindrical member 72 is formed by expanding the diameter of the first cylindrical portion 72 a that houses the driving device 3 and the rear of the first cylindrical portion 72 a, that is, between the first cylindrical portion 72 a and the lid member 73. Two cylinder portions 72b. The journal bearing 9 is connected to the step portion between the first cylindrical portion 72a and the second cylindrical portion 72b. The internal space of the second cylindrical portion 72b is a working space 71 for connecting wires and pipes (not shown) to components such as the driving device 3, the journal bearings 5, 9 and the thrust bearing 10 accommodated in the housing 7. Form. In order to perform installation and maintenance of each component through the work space 71, the work space 71 performs a predetermined work by an operator inserting a hand, a tool, or the like in addition to a space for housing piping and wiring. It requires as much space as possible and requires a certain volume.

  The lid member 73 has a wiring / pipe port 73 a for guiding the wiring and piping described above into the housing 7. The lid member 73 is connected to the housing 7 by a fastener (not shown) so as to seal the opening of the cylindrical member 72. At this time, the coupling surface between the lid member 73 and the cylindrical member 72 is sealed by the O-ring 75 disposed on the end surface of the cylindrical member 72.

  Here, since the inside of the housing | casing 7 is a structure which can be filled with the vaporized gas of a cryogenic refrigerant | coolant, it is preferable to set it as an oil-free structure. Therefore, it is preferable to employ non-contact type bearings for the driving device 3 and the rotating shaft 4. A gas bearing may be adopted as the bearing instead of the magnetic bearing. Although not shown, a cooling jacket capable of supplying and circulating cooling water may be disposed on the wall surface of the housing 7 facing the driving device 3.

  The filler 8 is a member that is disposed in a predetermined space in the housing 7 and reduces the volume of the space occupied by the gas in the housing 7. For example, as shown in FIG. 1, when the housing 7 has a work space 71 formed behind the drive device 3, the filler 8 is disposed in the work space 71. Thus, by filling the space of the housing 7 with an object (filler 8) having a constant volume, the space occupied by the gas in the housing 7 can be reduced, and the drive device 3 side and the impeller 2 side can be reduced. The total amount of gas reciprocating between the two can be reduced. Such a filler 8 can maintain a constant volume or shape even when exposed to a cryogenic atmosphere, does not react with the gas in the housing 7 and does not change in quality or produce a product, the driving device 3 and the rotating shaft Any member and shape may be used as long as the conditions such as not entering into the gap with 4 are satisfied. For example, the filler 8 is a plurality of spheres made of metal or ceramics as illustrated. As the metal, for example, stainless steel or the like can be used.

  As shown in FIGS. 1 and 2, the heat insulating material 12 is disposed between the impeller 2 and the journal bearing 5, and transfers heat between a low temperature atmosphere inside the vacuum vessel and a normal temperature atmosphere outside the vacuum vessel. Suppress. For the heat insulating material 12, for example, a material having low thermal conductivity and high durability against a cryogenic atmosphere such as glass fiber reinforced plastic or ceramics is employed.

  The heat insulating material 12 is formed in a substantially cylindrical shape that can be disposed between the casing 6 and the rotating shaft 4 and between the impeller 2 and the journal bearing 5, and is related to an opening 64 formed in the casing 6. A flange portion 12a that can be stopped is provided, and the flange portion 12a is sandwiched between the journal bearing 5 and the casing 6. Specifically, the lower surface of the flange portion 12 a is engaged with a recess 65 formed in the main body portion 6 a of the casing 6, and the upper surface of the flange portion 12 a is accommodated in the recess 52 formed in the journal bearing 5. Moreover, the step part 12b may be formed inside the heat insulating material 12 so that the surface of the rotating shaft 4 or the journal bearing 5 may be followed (for example, refer FIG.3 (b)).

  Further, as will be described later, a holding spring 13 is inserted between the flange portion 12a and the journal bearing 5 (see, for example, FIG. 3B). The presser spring 13 is a component for pressing the flange portion 12 a against the casing 6 and reducing the gap between the casing 6 and the heat insulating material 12.

  Here, the gas flow generated between the driving device 3 side and the impeller 2 side will be described with reference to FIG. The comparative example shown in FIG. 3A is a comparative example using a conventional journal bearing 50.

  In the comparative example shown in FIG. 3A, the journal bearing 50 is formed with openings 53 that penetrate both the upper and lower surfaces radially outward from the heat insulating material 120. The opening 53 is for reducing pressure fluctuations that occur between the impeller 20 side and the drive device 30 side.

  In such a comparative example, since the opening 53 is formed, the gas is easily reciprocated between the impeller 20 side and the drive device 30 side through the gap between the heat insulating material 120 and the casing 60. Yes. As a result, as shown by an arrow in FIG. 3A, the gas reciprocation between the impeller 20 side and the drive device 30 side through the gap between the heat insulating material 120 and the casing 60, the rotating shaft 40, Gas reciprocation occurs between the impeller 20 side and the drive device 30 side via a gap with the heat insulating material 120. Such reciprocation of the gas reduces the heat insulation effect of the heat insulating material 120 and causes the performance and efficiency of the entire apparatus to deteriorate. In addition, when low-temperature gas flows into the drive device 30 side, the device on the drive device 3 side that is normal temperature may be cooled. For example, when the O-ring on the drive device 30 side (for example, the O-rings 67 and 75 in the first embodiment) is cooled, the sealing performance is lowered, which may cause leakage of cryogenic gas.

  On the other hand, in the first embodiment shown in FIG. 3B, the journal bearing 5 has the above-described configuration, and the journal bearing 5 is not formed with the openings 53 penetrating both surfaces radially outward from the heat insulating material 12. . Therefore, the gas only reciprocates between the impeller 2 side and the drive device 3 side through the gap between the rotating shaft 4 and the heat insulating material 12. Therefore, the total amount of gas reciprocating between the impeller 2 side and the drive device 3 side can be reduced. As a result, it is possible to suppress problems such as the above-described degradation of the overall performance of the apparatus and the degradation of the sealing performance of the O-rings 67 and 75.

Next, a phenomenon that may occur when a gas flow (ventilation) occurs between the driving device 3 side and the impeller 2 side will be described. Here, FIG. 4 is a diagram showing the material characteristics of helium gas, hydrogen gas, and nitrogen gas. In FIG. 4, the horizontal axis represents temperature (K), and the vertical axis represents constant pressure specific heat (J / gK). Further, the graph of helium gas (He) is indicated by a solid line, the graph of hydrogen gas (H ₂ ) is indicated by a one-dot chain line, and the graph of nitrogen gas (N ₂ ) is indicated by a dotted line.

  Since the cryogenic rotating machine 1 according to the present embodiment is a rotating machine that sends cryogenic refrigerants such as liquid nitrogen, liquid helium, and liquid hydrogen, it is deeply related to the material characteristics of the gases constituting these cryogenic refrigerants. There is.

As shown in FIG. 4, the critical temperatures of helium gas (He), hydrogen gas (H ₂ ), and nitrogen gas (N ₂ ) are about 5.2K, about 33.0K, and about 126.2K, respectively. . In the vicinity of the critical temperature, the constant pressure specific heat rises rapidly, and the surrounding heat is likely to be taken away. In particular, when the housing 7 is filled with the vaporized gas of the cryogenic refrigerant and the pressure on the impeller 2 side (low temperature side) is higher than the pressure on the driving device 3 side (normal temperature side), the vaporization of the cryogenic refrigerant is performed. Gas will flow into the drive unit 3 side. At this time, the vaporized gas increases in temperature as it moves to the driving device 3 side (normal temperature side), and passes near the critical temperature. Therefore, when the vaporized gas passes the critical temperature, surrounding components are rapidly cooled. Such a phenomenon is also a phenomenon that occurs in the vicinity of the critical pressure.

  In order to suppress such cooling, it is effective to reduce the flow rate at which the vaporized gas flows from the impeller 2 side (low temperature side) to the drive device 3 side (normal temperature side). Therefore, in the cryogenic rotating machine 1 according to the first embodiment of the present invention, the volume occupied by the vaporized gas in the casing 7 is reduced by disposing the filler 8 in the casing 7, and from the impeller 2 side. The flow rate of the vaporized gas flowing into the driving device 3 is reduced. As a result, the total amount of vaporized gas reciprocating between the drive device 3 side and the impeller 2 side can be reduced, and reciprocation of the vaporized gas between the impeller 2 side and the drive device 3 side can be suppressed. .

  Next, a cryogenic rotating machine 1 according to another embodiment of the present invention will be described. Here, FIG. 5 is an enlarged view of the periphery of the casing showing another embodiment of the cryogenic rotating machine according to the present invention, (a) is the second embodiment, (b) is the third embodiment, c) shows a fourth embodiment. Moreover, in each figure, about the wiring and piping arrange | positioned in the work space 71, the figure is abbreviate | omitted for convenience of explanation. In addition, in each figure, about the same component as 1st embodiment shown in FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In the second embodiment shown in FIG. 5A, the filler 8 is constituted by blocks such as a plurality of cubes instead of a plurality of spheres. According to the second embodiment, compared to the case where the filler 8 is composed of a plurality of spheres, the gap of the work space 71 in the housing 7 can be efficiently filled, and the space occupied by the gas is effective. Can be reduced. In addition to the cube shown in the figure, blocks having various shapes such as a rectangular parallelepiped and a cylindrical body can be used.

  In the third embodiment shown in FIG. 5B, the filler 8 is composed of a plurality of spheres and blocks. According to the third embodiment, the block filler 8 is arranged at a place where the block is appropriate (for example, the outer peripheral portion of the work space 71), and the place where the sphere is suitable ( For example, by arranging the spherical filler 8 in the inner peripheral portion of the work space 71, the gap of the work space 71 in the housing 7 can be efficiently filled, and the space occupied by the gas is effective. Can be reduced.

  In the fourth embodiment shown in FIG. 5C, the filler 8 is constituted by a plurality of types of spheres. According to the fourth embodiment, compared with the case where the filler 8 is composed of one kind of sphere, the gap of the work space 71 in the housing 7 can be efficiently filled, and the space occupied by the gas can be reduced. It can be effectively reduced. Also, here, three sizes of large, medium, and small spheres (filler 8) are used. However, the present invention is not limited to this, and the filler 8 is a sphere of two types. It may be a sphere of four or more sizes. Moreover, you may make it comprise the filler 8 with the combination of a block of multiple types of magnitude | sizes, or a block, or a sphere.

  FIG. 6 is an enlarged view around a heat insulating material showing another embodiment of the cryogenic rotating machine 1 according to the present invention, in which (a) shows a fifth embodiment and (b) shows a sixth embodiment. Yes. Here, in the fifth embodiment and the sixth embodiment, the volume of the gap is increased while maintaining the gap between the heat insulating material 12, the casing 6, and the rotating shaft 4. According to these embodiments, by increasing the volume of the buffer region between the normal temperature driving device 3 side and the low temperature impeller 2 side, the pressure in the space close to the low temperature side can be reduced. It is possible to make it difficult for the vaporized gas on the side to flow into the drive device 3 side, and to reduce the reciprocation of the vaporized gas between the impeller 2 side and the drive device 3 side.

  In the fifth embodiment shown in FIG. 6A, the diameter D inside the cylinder of the rotating shaft 4 and the heat insulating material 12 is larger than that in the first embodiment. In the sixth embodiment shown in FIG. 6B, the length L of the portion where the rotating shaft 4 is inserted into the heat insulating material 12 is enlarged. Thus, by expanding the diameter D or the length L, the volume of the buffer region between the room temperature driving device 3 side and the cryogenic impeller 2 side can be easily increased. In the present embodiment, both the diameter D and the length L may be enlarged.

  In the first to sixth embodiments described above, the case where the cryogenic rotating machine 1 is a compressor has been described. However, the cryogenic rotating machine 1 may be a pump, a turbine, or other rotating machines similar to these.

  The present invention is not limited to the above-described embodiment, and the filler 8 may be made of a material other than ceramics or metal, neon gas or the like may be applied to a cryogenic refrigerant, and the gist of the present invention is not deviated. Of course, various changes can be made within the range.

DESCRIPTION OF SYMBOLS 1 ... Cryogenic rotating machine 2 ... Impeller 3 ... Drive apparatus 4 ... Rotating shafts 5, 9 ... Journal bearing 6 ... Casing 6a ... Main body part 6b ... Expanded diameter part 7 ... Housing 8 ... Filler 10 ... Thrust bearing 11 ... Upper part Bearing 12 ... Heat insulating material 12a ... Flange part 12b ... Step part 13 ... Holding spring 31 ... Rotor 32 ... Stator 51 ... Opening part 52 ... Recess 61 ... Suction port 62 ... Scroll part 63 ... Outlet pipe 64 ... Opening part 65 ... Recess 66 ... annular grooves 67 and 75 ... O-ring 71 ... work space 72 ... cylindrical member 72a ... first cylinder part 72b ... second cylinder part 73 ... lid member 73a ... wiring / piping port 74 ... annular groove

Claims (6)

In the cryogenic rotating machine in which the impeller side that imparts kinetic energy to the cryogenic refrigerant is disposed in a heat-insulated and cooled vacuum vessel, and the driving device side that rotates the impeller is disposed outside the vacuum vessel,
A rotating shaft for transmitting rotation of the driving device to the impeller;
A bearing for supporting the rotating shaft;
A casing that houses the impeller and is fixed to the vacuum vessel;
A housing that houses the driving device and is disposed on the back surface of the casing;
A filler disposed in the housing ,
The housing has a working space formed behind the driving device, and the filler is disposed in the working space.
A cryogenic rotating machine characterized by that.   The cryogenic rotary machine according to claim 1, wherein the filler is a member that reduces a volume of a space occupied by a gas in the casing.   The cryogenic rotary machine according to claim 1, wherein the filler is made of metal or ceramics.   The cryogenic rotating machine according to claim 1, wherein the filler is a plurality of spheres or blocks.   A heat insulating material disposed between the casing and the rotating shaft and between the impeller and the bearing, and maintaining the gap between the heat insulating material, the casing, and the rotating shaft; The cryogenic rotating machine according to claim 1, wherein the volume of the cryogenic rotating machine is increased.   The cryogenic rotary machine according to claim 1, wherein the bearing does not have an opening other than an opening through which the rotating shaft or the fixing member is inserted.