JP2011202588A - Centrifugal compressor - Google Patents

Abstract

Compressed air generated by rotation of a rotating shaft unit is used as effectively as possible, and the rotating shaft unit can be cooled efficiently and reliably.
In a casing 12 constituting a centrifugal compressor 10, a pressurizing air flow passage 76 for allowing compressed air from a scroll 70 to flow to a canceller chamber 36 and a branch from the pressurizing air flow passage 76 are branched. The cooling air flow passage 78 communicating with the central storage chamber 72 from between the stator 42 and the canceller chamber 36, and one end side communicating with the cooling air flow passage 78 are in contact with the outer surface of the rotor 20 and are compressed air. Is formed, and an axial cooling flow passage 80 whose other end is opened from the outer peripheral side of the impeller side bearing holder 57A to the outside of the housing 12 is formed.
[Selection] Figure 1

Description

  The present invention relates to a centrifugal compressor in which a rotor unit provided with a permanent magnet, a pair of bearing shafts, an impeller, and a rotary shaft unit provided with a thrust canceller shaft are accommodated in a casing.

  In general, a centrifugal compressor is employed as a supercharger that efficiently supplies compressed air. For example, various centrifugal compressors are used as an auxiliary machine that supplies compressed air to an engine or an auxiliary machine that supplies compressed air that is an oxidant gas to a fuel cell.

  In this type of centrifugal compressor, impellers are provided on both sides of the rotating shaft, and there is a problem that the entire centrifugal compressor is increased in size and weight. For this reason, in order to reduce the size and cost of the centrifugal compressor, a configuration in which an impeller is provided only on one of the rotating shafts is employed.

  For example, in the electric compressor disclosed in Patent Document 1, as shown in FIG. 8, an impeller 2, a rotating shaft 3, a thrust canceller 4, and a motor unit 5 are built in a housing 1. The rotary shaft 3 is pivotally supported by a thrust air bearing 6a and a radial air bearing 6b.

  Therefore, when the rotational speed of the impeller 2 increases, a thrust load is generated on the rotating shaft 3, while the pressure of the compressed air acts on the pressure chamber 7 from the compressed air outlet 8 through the compressed air passage 9. . For this reason, the pressure of the compressed air acts on the canceller shaft 4a, and the thrust load is canceled by causing the rotating shaft 3 to generate a load toward the rear.

JP 2009-257165 A

  By the way, in the above-described electric compressor, when the rotating shaft 3 is rotated at a high speed, a large centrifugal force acts on the permanent magnet disposed on the rotating shaft 3 and the rotor easily generates heat due to the eddy current. This heat may be demagnetized by being conducted to the permanent magnet. Moreover, the radial air bearing 6b is also easy to generate heat, and an efficient and economical cooling structure is desired.

  The present invention responds to this type of request, and it is possible to effectively utilize compressed air generated by the rotation of the rotating shaft unit as much as possible, and to cool the rotating shaft unit efficiently and reliably. An object of the present invention is to provide a centrifugal compressor.

  The present invention is provided with a rotor provided with a permanent magnet, a pair of bearing shafts provided at both axial ends of the rotor, an impeller provided at an end of one of the bearing shafts, and an end of the other bearing shaft. A rotary shaft unit including a thrust canceller shaft, a stator facing the outer peripheral surface of the rotor, an impeller side bearing holder and a thrust canceller side bearing holder for holding a pair of bearing shafts, and a scroll in which the impeller is housed, The present invention relates to a centrifugal compressor including a canceller chamber in which a thrust canceller shaft is accommodated, and a housing that further includes a pair of the bearing shaft and a central accommodating chamber in which the stator is accommodated.

  This centrifugal compressor has a pressurization air flow passage for allowing compressed air from the scroll to flow into the canceller chamber, a branch from the pressurization air flow passage, and a center between the stator and the canceller chamber. A cooling air flow passage that communicates with the storage chamber, one end side communicates with the cooling air flow passage, the compressed air is circulated in contact with the outer surface of the rotor, and the other end side from the outer peripheral side of the impeller side bearing holder An axial cooling flow passage that is open to the outside of the housing is formed.

  Moreover, it is preferable that the impeller side bearing holder and the thrust canceller side bearing holder are inclined toward the rotor side and provided with an inclined guide surface for guiding the compressed air.

  Furthermore, it is preferable that the casing forms a refrigerant flow path along the outer periphery of the stator, and the compressed air flow path extends along the outer periphery of the refrigerant flow path.

  Furthermore, it is preferable that a fin for heat dissipation is disposed along the outer periphery of the refrigerant flow path in the compressed air flow path.

  Moreover, it is preferable that a fin for heat radiation is formed on the impeller side bearing holder.

  In the present invention, a part of the compressed air generated when the impeller rotates flows into the canceller chamber from the pressurizing air flow passage to generate the canceller pressure, and the thrust canceller side bearing holder adjacent to the canceller chamber is provided. Can be cooled.

  For this reason, the compressed air introduced into the cooling airflow passage branched from the pressurization airflow passage absorbs heat from the thrust canceller side bearing holder when it flows from between the stator and the canceller chamber to the central storage chamber. Temperature does not increase. Accordingly, in the axial cooling flow passage, relatively low-temperature compressed air flows in contact with the outer surface of the rotor, and the rotor can be cooled well and reliably. Further, the compression for cooling is discharged from the outer peripheral side of the impeller side bearing holder to the outside of the housing, so that the impeller side bearing holder can be effectively cooled.

  As a result, the compressed air generated by the rotation of the rotating shaft unit can be effectively utilized as much as possible, and the rotating shaft unit can be efficiently and reliably cooled.

It is a section explanatory view of the centrifugal compressor concerning a 1st embodiment of the present invention. It is principal part sectional explanatory drawing of the said centrifugal compressor. It is the III-III sectional view taken on the line of the centrifugal compressor in FIG. It is a perspective explanatory view of a thrust air bearing constituting the centrifugal compressor. FIG. 5 is a sectional view of the thrust air bearing taken along line VV in FIG. 4. It is a section explanatory view of the centrifugal compressor concerning a 2nd embodiment of the present invention. It is a section explanatory view of the centrifugal compressor concerning a 3rd embodiment of the present invention. It is explanatory drawing of the electric compressor currently disclosed by patent document 1. FIG.

  As shown in FIG. 1, the centrifugal compressor (electric centrifugal compressor) 10 according to the first embodiment of the present invention includes a housing 12. A rotating shaft unit 14 is rotatably mounted in the housing 12.

  As shown in FIGS. 1 and 2, the rotary shaft unit 14 is provided with an annular permanent magnet 16 and a cylindrical shape that is provided on the outer periphery of the permanent magnet 16 and accommodates (for example, shrink fit) the permanent magnet 16. The rotor 20 constituted by the protective ring 18, at least one of axial end portions of the rotor 20, in the first embodiment, bearing shafts 22, 24 provided on both, and the rotor 20 of the bearing shaft 22. An impeller 26 provided at an axial end opposite to the side is provided.

  The impeller 26 constitutes a centrifugal compression part 28 and an end surface thereof abuts on the large diameter part 30 a of the tension shaft 30. On the tension shaft 30, the bearing shaft 22, the rotor 20, and the bearing shaft 24 are arranged in this order from the impeller 26 side, and these are integrally held by a fixing member 32 that is screwed into the tension shaft 30.

  The fixed member 32 is provided with a canceller mechanism 34 having a function of reducing the thrust force generated in the direction of the arrow A1 when the rotary shaft unit 14 rotates. As shown in FIG. 1, the canceller mechanism 34 includes a thrust canceller shaft 38 that can slide in a canceller chamber (pressurizing chamber) 36 in the direction of arrow A.

  An annular stator 42 is mounted in the casing 12 so as to be positioned on the outer periphery of the rotor 20. The stator 42 and the rotor 20 constitute a motor unit 46.

  The protection ring 18 constituting the rotor 20 is required to have high rigidity and is made of a nickel-based superalloy, for example, Inconel (trade name of Special Metal). A plurality of cooling water flow paths (refrigerant flow paths) 48 are formed around the outer periphery of the stator 42.

  As shown in FIG. 2, the protection ring 18 is provided with cylindrical protrusions 18 a and 18 b protruding outward in the axial direction from the end surfaces 16 a and 16 b of the permanent magnet 16 on the end surfaces where the bearing shafts 22 and 24 are provided.

  The bearing shaft 22 has a cylindrical portion 22a opened at one end in the axial direction, and forms a bottom portion 22b protruding radially inward at the other end in the axial direction. Similarly, the bearing shaft 24 has a cylindrical portion 24a opened at one axial end and a bottom 24b projecting radially inward at the other axial end.

  The bottom 22b of the bearing shaft 22 is in contact with one cylindrical protrusion 18a of the protection ring 18, and the bottom 24b of the bearing shaft 24 is in contact with the other cylindrical protrusion 18b of the protection ring 18. The bottom portions 22b and 24b and the end surfaces 16a and 16b of the permanent magnet 16 are separated by distances S1 and S2, respectively.

  A foil type gas bearing 50 is provided which faces the outer peripheral surfaces of the bearing shafts 22 and 24 and holds the bearing shafts 22 and 24. The foil type gas bearing 50 includes journal air bearings 52 a and 52 b that hold the radial positions of the bearing shafts 22 and 24, and a thrust air bearing 54 that holds the axial position of the bearing shaft 22.

  The bearing shafts 22 and 24 constitute journal air bearings 52a and 52b, and are made of, for example, a nickel-based superalloy that is the same material as the protective ring 18. Each of the journal air bearings 52a and 52b includes ring members 56A and 56B that are arranged with a predetermined gap around the outer periphery of the bearing shafts 22 and 24.

  The ring members 56A, 56B rotatably support the bearing shafts 22, 24, and are fixed to the impeller side bearing holder 57A and the thrust canceller side bearing holder 57B so as not to rotate. The impeller side bearing holder 57A and the thrust canceller side bearing holder 57B are provided with inclined guide surfaces 57a and 57b which are inclined in a tapered shape or an arc shape toward the rotor 20 side.

  As shown in FIG. 3, the corrugated bump foil 58 and the flat top foil 60 are arranged in this order on the inner peripheral surface 56 a of the ring member 56 </ b> A. The bump foil 58 is composed of one sheet or a plurality of sheets. One end 58a of the bump foil 58 is welded to the inner peripheral surface 56a of the ring member 56A, and the other end forms a free end. The top foil 60 has a flat plate curved in an annular shape, and one end 60a is welded to the inner peripheral surface 56a of the ring member 56A, while the other end is a free end. The ring member 56B is configured similarly to the ring member 56A described above.

  As shown in FIGS. 1 and 2, a large-diameter flange portion 62 constituting a thrust air bearing 54 is provided on the outer peripheral portion of the bearing shaft 22. Ring members 64a and 64b are arranged on both sides in the axial direction across the large-diameter flange portion 62.

  As shown in FIG. 4, the ring members 64 a and 64 b are provided with a corrugated bump foil 66 and a flat top foil 68 on the surfaces facing the large-diameter flange portion 62. A plurality of the bump foil 66 and the top foil 68 are arranged in an annular shape around the inner peripheral surfaces of the ring members 64a and 64b.

  As shown in FIG. 5, each bump foil 66 has one end 66a welded to the ring members 64a and 64b and the other end 66b constituting a free end. Each top foil 68 has one end 68a welded to the ring members 64a and 64b, while the other end 68b is a free end.

  As shown in FIG. 2, the axial end portion 26 a of the impeller 26 is fitted coaxially to the cylindrical portion 22 a of the bearing shaft 22 (inlay structure). As for the bearing shafts 22 and 24, each bottom part 22b and 24b fits coaxially to the cylindrical projection parts 18a and 18b of the protection ring 18 (inlay structure).

  The housing 12 is provided with a scroll 70 for storing the impeller 26, a canceller chamber 36 for storing the thrust canceller shaft 38, a central storage chamber 72 for storing the pair of bearing shafts 22 and 24, and the stator 42, and The scroll 70 is provided with a compressor outlet 74.

  As shown in FIGS. 1 and 2, in the casing 12, a pressurizing air flow passage 76 for allowing compressed air from the scroll 70 to flow to the canceller chamber 36, and a branch from the pressurizing air flow passage 76, are provided. The cooling air flow passage 78 communicated with the central storage chamber 72 from between 42 and the canceller chamber 36, and one end side communicates with the cooling air flow passage 78, and the compressed air flows in contact with the outer surface of the rotor 20. In addition, an axial cooling flow passage 80 is formed in which the other end side is opened from the outer peripheral side of the impeller side bearing holder 57A to the outside of the housing 12. The pressurizing air flow passage 76 bypasses the central storage chamber 72 and extends along the outer periphery of the cooling water passage 48.

  The operation of the centrifugal compressor 10 configured as described above will be described below.

  First, by energizing the stator 42 constituting the electric motor, the permanent magnet 16 and the protective ring 18 constituting the rotor 20 rotate integrally with the tension shaft 30. For this reason, the impeller 26 held by the tension shaft 30 rotates at a relatively high speed, and air is sucked from the atmosphere via the centrifugal compressor 28.

  The air sucked by the impeller 26 is pumped by the centrifugal compressor 28 and is sent to, for example, an oxidant gas supply system of a fuel cell (not shown). Fuel gas (hydrogen gas) is supplied to the fuel cell from a fuel gas supply system (not shown). Therefore, power generation is performed by a reaction between air supplied to the cathode side and hydrogen supplied to the anode side.

  In this case, in the first embodiment, a part of the compressed air sucked by the centrifugal compression unit 28 bypasses the central storage chamber 72 and flows into the canceller chamber 36 from the pressurizing air flow passage 76. Therefore, a canceller pressure is generated by the compressed air in the canceller chamber 36, and the thrust canceller shaft 38 is urged in the direction of the arrow A2 in the canceller chamber 36.

  Accordingly, the thrust force generated in the direction of the arrow A1 when the rotary shaft unit 14 rotates is effectively reduced. At this time, the thrust canceller side bearing holder 57B adjacent to the canceller chamber 36 is cooled via the compressed air flowing into the canceller chamber 36.

  On the other hand, a part of the compressed air is introduced into the cooling air flow passage 78 branched from the pressurization air flow passage 76. When the compressed air introduced into the cooling air flow passage 78 flows from between the stator 42 and the canceller chamber 36 to the central storage chamber 72, the compressed air absorbs heat from the thrust canceller side bearing holder 57B and rises in temperature. There is no. This is because the thrust canceller side bearing holder 57B is cooled via the compressed air flowing into the canceller chamber 36 as described above.

  Thereby, in the axial cooling flow passage 80, compressed air having a relatively low temperature flows in contact with the outer surface of the rotor 20, and the rotor 20 can be cooled well and reliably. In addition, the compressed air for cooling is discharged from the outer peripheral side of the impeller side bearing holder 57A to the outside of the housing 12, whereby the impeller side bearing holder 57A can be effectively cooled.

  For this reason, it is possible to effectively use the compressed air generated by the rotation of the rotating shaft unit 14 as much as possible and to cool the rotating shaft unit 14 efficiently and reliably.

  Further, the compressed air for cooling smoothly flows toward the rotor 20 under the guiding action of the inclined guide surface 57b formed in the thrust canceller side bearing holder 57B. Therefore, the rotor 20 can be efficiently cooled. On the other hand, an inclined guide surface 57a is formed on the impeller side bearing holder 57A, and the impeller side bearing holder 57A can be satisfactorily cooled under the guiding action of the inclined guide surface 57a.

  Further, the pressurizing air flow passage 76 extends along the outer periphery of the cooling water passage 48. As a result, the compressed air flowing through the pressurizing air flow passage 76 is cooled under the action of the cooling water passage 48 and then supplied to the canceller chamber 36 and the axial cooling flow passage 80, so that a good cooling performance is obtained. It is done.

  Furthermore, the pressure inside the housing 12 is maintained at the same pressure as the pressure inside the canceller chamber 36. For this reason, the viscosity of air rises, and in particular, the foil type gas bearing 50 has the advantage that the ability to form an air film is improved and it can contribute to stable rotation.

  FIG. 6 is a cross-sectional explanatory view of a centrifugal compressor 90 according to the second embodiment of the present invention.

  In addition, the same referential mark is attached | subjected to the component same as the centrifugal compressor 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  The centrifugal compressor 90 includes a housing 92, and a pressurizing air flow passage 94 for allowing the compressed air from the scroll 70 to flow into the canceller chamber 36 is provided in the housing 92. 76 is provided instead of 76. In the pressurizing air flow passage 94, heat dissipating fins 96 are disposed along the outer periphery of the refrigerant flow path 48.

  In the second embodiment configured as described above, the same effects as those of the first embodiment described above can be obtained. In particular, the compressed air introduced into the pressurizing air flow passage 94 can be It is cooled well under the heat radiation action of the heat radiation fin 96 extending along the outer periphery.

  Accordingly, the compressed air is once cooled by flowing through the pressurizing air flow passage 94 and then supplied to the canceller chamber 36 and the axial cooling flow passage 80. For this reason, the compressed air immediately before cooling the rotor 20 can be cooled in advance, and there is an advantage that the cooling effect by the compressed air is further improved.

  FIG. 7 is an explanatory cross-sectional view of a centrifugal compressor 100 according to the third embodiment of the present invention.

  In the casing 12 constituting the centrifugal compressor 100, an impeller side bearing holder 102A is provided in place of the impeller side bearing holder 57A. A plurality of heat dissipating fins 104 are formed along the inclined guide surface 57a in the impeller side bearing holder 102A.

  In the third embodiment configured as described above, the same effects as those of the first embodiment can be obtained. In particular, the compressed air that has been heated by cooling the rotor 20 has a plurality of heat dissipating fins 104. It is possible to efficiently cool the impeller side bearing holder 102 </ b> A in which is formed.

  In the third embodiment, the configuration of the second embodiment can be used together. Thereby, there exists an advantage that the cooling performance by compressed air improves at a stretch.

DESCRIPTION OF SYMBOLS 10, 90, 100 ... Centrifugal compressor 12, 92 ... Case 14 ... Rotating shaft unit 16 ... Permanent magnet 18 ... Protection ring 20 ... Rotor 22, 24 ... Bearing shaft 22a, 24a ... Cylindrical shape part 22b, 24b ... Bottom part 26 ... Impeller 30 ... Tension shaft 32 ... Fixed member 34 ... Canceller mechanism 36 ... Canceller chamber 38 ... Thrust canceller shaft 42 ... Stator 46 ... Motor section 48 ... Cooling water flow path 50 ... Foil type gas bearings 52a, 52b ... Journal air bearing 54 ... thrust air bearings 56A and 56B ... ring member 56a ... inner peripheral surface 57A and 102A ... impeller side bearing holders 57a and 57b ... inclined guide surface 57B ... thrust canceller side bearing holders 58 and 66 ... bump foils 60 and 68 ... top foil 70 ... scroll 72 Central storage chamber 76,94 ... pressurization air passages 78 ... cooling air flow passage 80 ... axial cooling passages 96 and 104 ... radiation fins

Claims (5)

A rotor provided with a permanent magnet, a pair of bearing shafts provided at both axial ends of the rotor, an impeller provided at one end of the bearing shaft, and a thrust canceller shaft provided at an end of the other bearing shaft A rotating shaft unit comprising:
A stator facing the outer peripheral surface of the rotor;
An impeller side bearing holder and a thrust canceller side bearing holder for holding the pair of bearing shafts;
A casing for providing a scroll for storing the impeller, a canceller chamber for storing the thrust canceller shaft, and a central storage chamber for storing the pair of bearing shafts and the stator;
A centrifugal compressor comprising:
In the housing, an air flow passage for pressurizing the compressed air from the scroll to flow to the canceller chamber,
A cooling air flow passage branched from the pressurizing air flow passage and communicating with the central storage chamber from between the stator and the canceller chamber;
A shaft whose one end is in communication with the cooling air flow passage, is in contact with the outer surface of the rotor and through which compressed air is circulated, and whose other end is open from the outer peripheral side of the impeller bearing holder to the outside of the housing A cooling flow path,
A centrifugal compressor characterized in that is formed.   2. The centrifugal compressor according to claim 1, wherein the impeller side bearing holder and the thrust canceller side bearing holder are inclined toward the rotor side and provided with an inclined guide surface for guiding the compressed air. Centrifugal compressor. The centrifugal compressor according to claim 1 or 2, wherein the casing forms a refrigerant flow path along an outer periphery of the stator.
The centrifugal compressor is characterized in that the compressed air flow passage extends along an outer periphery of the refrigerant flow path.   4. The centrifugal compressor according to claim 3, wherein heat radiation fins are disposed along an outer periphery of the refrigerant flow path in the compressed air flow passage.   The centrifugal compressor according to any one of claims 1 to 4, wherein the impeller side bearing holder is formed with heat radiation fins.

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