JP5174069B2 - Centrifugal compressor - Google Patents

Description

  The present invention relates to an impeller for compressing air, a rotor provided with a permanent magnet, and a centrifugal compressor including a bearing shaft constituting a gas bearing.

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

  In this type of centrifugal compressor, a rotor having a permanent magnet is provided on the inner peripheral side of an annularly arranged stator, and the rotor is energized by energizing the winding wound around the stator. It is configured to be rotated.

  In recent years, it has been desired to rotate the rotor at a high speed. At that time, gas bearings and magnetic bearings are employed as bearings for supporting a rotor that rotates at high speed, because rotational accuracy is obtained with a relatively simple configuration and wear is suppressed in a non-contact manner.

  For example, in the compressor disclosed in Patent Document 1, the shaft 1 is supported by journal bearings 2a and 2b and a thrust bearing 3 as shown in FIG. The journal bearings 2a and 2b are air lubricated tilting pad journal bearings.

  A first stage impeller rotor 4a is mounted on one end side of the shaft 1, and second and third stage impeller rotors 4b and 4c are mounted on the other end side. Between the impeller rotors 4a and 4b, a motor having a rotor 5 made of a permanent magnet attached to the shaft 1 and a stator 6 attached in the housing is disposed. The impeller rotor 4a, the shaft 1, and the impeller rotors 4b and 4c are integrally clamped and held by a tie shaft 7 extending in the axial direction.

Japanese National Patent Publication No. 9-509999

  However, in Patent Document 1 described above, the shaft length of the tie shaft 7 that holds the impeller rotor 4a, the shaft 1, and the impeller rotors 4b and 4c coaxially and integrally is considerably increased. For this reason, there is a problem that the processing of the tie shaft 7 becomes complicated and the material cost increases. In addition, the long tie shaft 7 has a problem that the resonance frequency is lowered and the resonance strength is significantly reduced.

  The present invention solves this type of problem, and an object of the present invention is to provide a centrifugal compressor that can shorten the tie shaft well and improve the resonance strength.

  The present invention includes an impeller for compressing air, a rotor provided with a permanent magnet, and a bearing shaft constituting a gas bearing. At least the impeller, the rotor, and the bearing shaft are coaxial with a tie shaft inserted in an axial direction. The present invention relates to a centrifugal compressor integrally held on top.

  The bearing shaft has a first bottom portion protruding radially inward at one axial end adjacent to the rotor and a first cylindrical portion opened at the other axial end, and adjacent to the bearing shaft. Thus, the receiving member is arranged coaxially.

  The receiving member is set to have an outer diameter smaller than the inner diameter of the first cylindrical portion, and has a second bottom portion protruding radially inward at one end in the axial direction and abutting against the first bottom portion, and at the other end in the axial direction. A second cylindrical portion to be opened is provided.

  The tie shaft is integrally inserted into the center of the second bottom portion of the receiving member, the center of the first bottom portion of the bearing shaft, the shaft core of the rotor and the shaft core of the impeller, and from the end portion on the impeller side. A shaft portion fixed by a tightening tool and an end portion opposite to the end portion to which the tightening tool is fixed, and at least from the through hole provided at the center of the second bottom portion of the receiving member And a head that is configured to have a large diameter and that is locked to the second bottom portion of the receiving member.

  The centrifugal compressor includes a thrust shaft for suppressing the axial movement of the tie shaft during rotation, and the thrust shaft has an outer diameter smaller than the inner diameter of the first cylindrical portion of the bearing shaft. The receiving member is provided with a pressing portion that is set to have a larger diameter than the inner diameter of the thrust shaft, and the thrust shaft includes an opening-side end surface of the bearing shaft, the pressing portion, and the like. It is preferable to interpose between.

  Further, in this centrifugal compressor, it is preferable that a bearing shaft constituting a thrust air bearing and a journal air bearing be coaxially disposed between the impeller and the rotor.

  Furthermore, in this centrifugal compressor, it is preferable that a resolver rotor is interposed between the thrust shaft and the pressing portion.

  Moreover, it is preferable that this centrifugal compressor is provided with a gap sensor so as to face the pressing portion.

  In the present invention, the second cylindrical part of the receiving member is inserted into the first cylindrical part of the bearing shaft, and the second bottom part of the second cylindrical part is located at the first bottom part of the first cylindrical part. It is in contact. That is, the second bottom portion of the receiving member is inserted into the bearing shaft and arranged as close as possible to the rotor side.

  In this state, the tie shaft is integrally inserted into a through hole formed in the center of the second bottom portion of the receiving member, the center of the first bottom portion of the bearing shaft, the shaft core of the rotor, and the shaft core of the impeller. It is fixed with a fastening tool from the end.

  Accordingly, the shaft length of the tie shaft can be greatly shortened, the manufacturability can be improved and the cost can be easily reduced, and the resonance frequency can be increased. As a result, the resonance strength of the tie shaft can be improved, and high-speed rotation can be efficiently performed with a simple shaft design.

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 principal part sectional explanatory drawing of the centrifugal compressor which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of the compressor currently disclosed by patent document 1. FIG.

  As shown in FIG. 1, the centrifugal compressor (supercharger) 10 according to the first embodiment of the present invention includes a casing 12. A rotating shaft unit 14 is rotatably mounted in the casing 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, the rotor shaft 20 side of the bearing shaft 22 And an impeller 26 provided at the opposite axial end.

  The impeller 26 constitutes a centrifugal compression unit 28, and the bearing shaft 22, the rotor 20, the bearing shaft 24, and the receiving member 32 are arranged on the tie shaft 30 in this order from the impeller 26 side. On the receiving member 32 side, a canceller mechanism 34 having a function of relieving a thrust force generated in the arrow A1 direction when the rotary shaft unit 14 rotates is provided.

  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 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 is provided with a first cylindrical portion 22a having a first bottom portion 22b protruding radially inward at one axial end adjacent to the rotor 20 and opened at the other axial end. Similarly, the bearing shaft 24 has a first cylindrical portion 24a having a first bottom portion 24b protruding radially inward at one axial end adjacent to the rotor 20 and opened at the other axial end.

  The first bottom portion 22b of the bearing shaft 22 is in contact with one cylindrical protrusion 18a of the protective ring 18, and the first bottom portion 24b of the bearing shaft 24 is in contact with the other cylindrical protrusion 18b of the protective ring 18. . The first 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 and 56B rotatably support the bearing shafts 22 and 24 and are fixed so as not to rotate.

  As shown in FIG. 3, a corrugated bump foil 58 and a flat top foil 60 are arranged in this order on the inner peripheral surface 56a of the ring member 56A. 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 receiving member 32 is provided with a second cylindrical portion 32 a set to an outer diameter smaller than the inner diameter of the first cylindrical portion 24 a constituting the bearing shaft 24. A second bottom portion 32 b that protrudes inward in the radial direction and contacts the first bottom portion 24 b of the bearing shaft 24 is provided at one axial end of the second cylindrical portion 32 a on the rotor 20 side. The second cylindrical portion 32a is opened at the other end in the axial direction, and a pressing portion 32c having a larger diameter than the outer diameter of the second cylindrical portion 32a is integrally provided at the other end in the axial direction. .

  The tie shaft 30 includes a center of the second bottom 32b of the receiving member 32, a center of the first bottom 24b of the bearing shaft 24, an axis of the permanent magnet 16 (rotor 20), a center of the first bottom 22b of the bearing shaft 22, and an impeller. The through holes 70a, 70b, 70c, 70d, and 70e respectively formed in the 26 shaft cores have shaft portions 30a that are integrally inserted from the receiving member 32 side. A screw portion 30b is formed at the tip end side of the shaft portion 30a in the direction of arrow A1, that is, the end portion on the impeller 26 side, and a nut member (fastening tool) 72 is fixed to the screw portion 30b.

  An end portion of the shaft portion 30a in the arrow A2 direction is configured to have a diameter larger than at least the through hole 70a provided at the center of the second bottom portion 32b of the receiving member 32 and is locked to the second bottom portion 32b. The head 30c is integrally formed.

  As shown in FIG. 1, the canceller mechanism 34 includes a thrust shaft 76 that can slide in the direction of arrow A in the pressurizing chamber 74. Air generated by the rotation of the impeller 26 flows into the pressurizing chamber 74 through the passage 78.

  As shown in FIG. 2, the thrust shaft 76 has an annular portion 76 a set to an outer diameter smaller than the inner diameter of the first cylindrical portion 24 a of the bearing shaft 24, while the pressing portion 32 c of the receiving member 32. Is set larger than the inner diameter of the thrust shaft 76. The thrust shaft 76 is interposed between the open end surface of the bearing shaft 24 and the pressing portion 32c.

  On the outer periphery of the receiving member 32, a resolver rotor 80 is refurbished between the thrust shaft 76 and the pressing portion 32c, and a gap sensor 82 is disposed facing the pressing portion 32c.

  In the casing 12, as shown in FIG. 1, a refrigerant flow passage 84 is formed between the protective ring 18 constituting the motor unit 46 and the stator 42. The inlet side of the flow passage 84 and the passage 78 of the canceller mechanism 34 communicate with the compressor outlet 86 of the centrifugal compressor 28. The air compressed by the rotation of the impeller 26 is sent from the compressor outlet 86 to the inlet side of the flow passage 84 and the passage 78 of the canceller mechanism 34.

  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 tie shaft 30. For this reason, the impeller 26 held by the tie shaft 30 rotates at a relatively high speed, and air is sucked from the atmosphere via the centrifugal compression unit 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.

  A part of the air sucked by the centrifugal compression unit 28 is compressed and supplied from the compressor outlet 86 to the flow passage 84 in the casing 12. The cooling air that has passed through the flow passage 84 and has cooled the motor unit 46 is discharged to the outside.

  A part of the air sucked by the centrifugal compressor 28 is compressed and supplied from the compressor outlet 86 to the pressurizing chamber 74 through a passage 78 constituting the canceller mechanism 34. Accordingly, a thrust force is applied to the thrust shaft 76 disposed in the pressurizing chamber 74 in a direction away from the impeller 26 (arrow A2 direction). Thereby, the thrust force acting in the direction of the arrow A <b> 1 by the rotation of the impeller 26 is alleviated by the canceller mechanism 34.

  On the other hand, when the receiving member 32 held by the tie shaft 30 rotates, the resolver rotor 80 sandwiched between the thrust shaft 76 and the pressing portion 32c rotates with respect to the outer periphery of the receiving member 32. For this reason, the rotation angle position of the rotating shaft unit 14 is detected. Further, the rotation blur or the like of the rotary shaft unit 14 is detected by the gap sensor 82 arranged to face the pressing portion 32c of the receiving member 32.

  In this case, in the first embodiment, the bearing shaft 24 is configured in a cylindrical shape having a first bottom portion 24 b adjacent to the rotor 20, and the second cylindrical shape portion 32 a of the receiving member 32 is configured as the bearing shaft 24. In other words, it is inserted into the first cylindrical portion 24a. The second bottom portion 32 b of the receiving member 32 is in contact with the first bottom portion 24 b of the bearing shaft 24. That is, the second bottom portion 32 b of the receiving member 32 can be inserted into the bearing shaft 24 and disposed as close as possible to the rotor 20.

  In this state, the tie shaft 30 includes the center of the second bottom 32b of the receiving member 32, the center of the first bottom 24b of the bearing shaft 24, the axis of the rotor 20, the center of the first bottom 22b of the bearing shaft 22, and the impeller 26. A nut member 72 is fixed to a threaded portion 30b that is integrally inserted into each of the through holes 70a to 70e formed in the shaft core and provided at the end portion on the impeller 26 side.

  Therefore, the shaft length of the tie shaft 30 is greatly shortened, and the resonance frequency can be increased. As a result, the resonance strength of the tie shaft 30 can be improved, and an effect that high-speed rotation is efficiently performed can be obtained.

  Further, in the first embodiment, the resolver rotor 80 is disposed on the outer peripheral portion of the receiving member 32 between the pressing portion 32c and the thrust shaft 76, and the gap sensor 82 is disposed to face the pressing portion 32c. Has been. For this reason, there is an advantage that a sufficient measurement area (surface to be measured) of the gap sensor 82 can be secured, and good measurement performance can be maintained.

  FIG. 6 is a cross-sectional explanatory view of a main part 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.

  The rotary shaft unit 92 constituting the centrifugal compressor 90 includes a tie shaft 94 instead of the tie shaft 30 described above, and uses an impeller 96 instead of the impeller 26 described above. The impeller 96 is provided with a hole 98a corresponding to the through hole 70e in the shaft core, and a large-diameter hole 98b communicates with the hole 98a through a stepped portion.

  In the tie shaft 94, the end portion of the shaft portion 30a terminates at the tip portion of the impeller 96, and the screw portion 30b is disposed in the large-diameter hole portion 98b. When the nut member (clamping tool) 100 is screwed into the screw portion 30b, the receiving member 32, the bearing shaft 24, the rotor 20, the bearing shaft 22 and the impeller 96 are coaxially and integrally formed with the tie shaft 94. Retained.

  In the second embodiment configured as described above, the nut member 100 is accommodated in the large-diameter hole portion 98b formed in the impeller 96, so that the end portion of the tie shaft 94 is exposed from the tip end of the impeller 96. There is no. Thereby, the axial length of the tie shaft 94 is further shortened, and an effect that the resonance frequency can be further increased is obtained.

DESCRIPTION OF SYMBOLS 10 ... Centrifugal compressor 12 ... Casing 14 ... Rotary shaft unit 16 ... Permanent magnet 16a, 16b ... End surface 18 ... Protection ring 18a, 18b ... Cylindrical protrusion 20 ... Rotor 22, 24 ... Bearing shaft 22a, 24a, 32a ... Cylindrical portions 22b, 24b, 32b ... bottom 26 ... impeller 30 ... tie shaft 32 ... receiving member 32c ... pressing part 34 ... canceller mechanism 42 ... stator 46 ... motor part 50 ... foil type gas bearings 52a, 52b ... journal air bearing 54 ... Thrust air bearings 56A, 56B ... Ring members 70a to 70e ... Through holes 72 ... Nut member 74 ... Pressurizing chamber 76 ... Thrust shaft 76a ... Ring portion 80 ... Resolver rotor 82 ... Gap sensor

Claims (5)

An impeller for compressing air, a rotor provided with a permanent magnet, and a bearing shaft constituting a gas bearing are provided. At least the impeller, the rotor, and the bearing shaft are coaxially and integrally formed by a tie shaft inserted in an axial direction. A centrifugal compressor to be held,
The bearing shaft has a first bottom portion projecting radially inward at one axial end adjacent to the rotor and a first cylindrical portion that is opened at the other axial end, and
A receiving member is coaxially disposed adjacent to the bearing shaft,
The receiving member is set to an outer diameter smaller than the inner diameter of the first cylindrical portion, and has a second bottom portion protruding radially inward at one end in the axial direction and abutting against the first bottom portion. A second cylindrical portion is provided at the other end;
The tie shaft is integrally inserted into a through hole formed in the center of the second bottom portion of the receiving member, the center of the first bottom portion of the bearing shaft, the shaft core of the rotor and the shaft core of the impeller, A shaft portion fixed by a fastening tool from an end portion on the impeller side;
The receiving member is provided at an end opposite to the end to which the fastening tool is fixed and has a diameter larger than at least the through hole provided at the center of the second bottom of the receiving member. A head locked to the second bottom of
A centrifugal compressor characterized by comprising: The centrifugal compressor according to claim 1, further comprising a thrust shaft for suppressing axial movement of the tie shaft during rotation,
While the thrust shaft has an annular portion set to an outer diameter smaller than the inner diameter dimension of the first cylindrical portion of the bearing shaft,
The receiving member is provided with a pressing portion that is set to have a larger diameter than the inner diameter of the thrust shaft,
The centrifugal compressor, wherein the thrust shaft is interposed between an open side end surface of the bearing shaft and the pressing portion.   3. The centrifugal compressor according to claim 1, wherein a bearing shaft constituting a thrust air bearing and a journal air bearing is coaxially disposed between the impeller and the rotor. Mold compressor.   4. The centrifugal compressor according to claim 2, wherein a resolver rotor is interposed between the thrust shaft and the pressing portion.   The centrifugal compressor according to any one of claims 2 to 4, wherein a gap sensor is disposed to face the pressing portion.

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