JP2011188612A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent irreversible demagnetization of a permanent magnet and improve axial strength. <P>SOLUTION: A rotating shaft unit 14 constituting a centrifugal compressor 10 includes a rotor 20, and bearing shafts 22 and 24 arranged at both axial ends of the rotor 20. In the rotor 20, a permanent magnet 16, a guard ring 18 formed of a metallic member, and a filament winding layer 19 with a fiber member wound therearound are stacked in this order from radially inside to radially outside. The guard ring 18 has swelling parts 18a which swell outward from both axial ends of the filament winding layer 19, and diameter-expanded parts 18c which project radially outward from the swelling parts 18a and has axially outer ends which constitute contact faces 18b to be in contact with the bearing shafts 22 and 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor comprising: a rotary shaft unit provided with an impeller at at least one end; and a stator provided in a casing in which the rotary shaft unit is accommodated and opposed to an outer peripheral surface of the rotary shaft unit. .

  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.

  However, when the rotor is rotated at a high speed, a large centrifugal force acts on the permanent magnet disposed in the rotor, and the rotor generates heat due to eddy current, and this heat is conducted to the permanent magnet, thereby causing the permanent magnet to move. There is a problem of demagnetization. In particular, non-contact gas bearings and magnetic bearings are less susceptible to heat transfer and are greatly affected by heat generation.

  Therefore, for example, a rotating machine disclosed in Patent Document 1 is known. As shown in FIG. 8, the rotor constituting the rotating machine has a permanent magnet 2 fixed to the outer periphery of a metal shaft 1 at the center by a cold fit.

  A protective ring 3 made of a heat-resistant and high-strength material having high-temperature mechanical properties such as Inconel (trade name of Special Metal Co.) is provided on the outer periphery of the permanent magnet 2, and carbon fiber or the like is provided on the outer periphery of the protective ring 3. A protective layer 4 in which the non-conductive fiber is wound by filament winding is provided. Thus, the problem of magnet demagnetization can be solved without increasing the temperature of the rotor.

JP 2008-219965 A

  However, in Patent Document 1 described above, since the protective layer 4 is nonconductive, no eddy current is generated, but a large amount of eddy current is generated in the protective ring 3 to generate heat. Therefore, there is a problem that irreversible demagnetization is induced in the permanent magnet 2.

  In addition, although the protective layer 4 prevents the permanent magnets 2 from scattering, the shaft 1 extends in the center of the rotor to form the shaft structure, so that there is a problem that the resonance strength is significantly reduced.

  The present invention solves this type of problem, and an object thereof is to provide a centrifugal compressor capable of preventing irreversible demagnetization of a permanent magnet and improving shaft strength.

  The present invention relates to a centrifugal compressor comprising: a rotary shaft unit provided with an impeller at at least one end; and a stator provided in a casing in which the rotary shaft unit is accommodated and opposed to an outer peripheral surface of the rotary shaft unit. Is.

  The rotating shaft unit includes a cylindrical rotor and bearing shafts having the same diameter as the rotor and disposed at both axial ends of the rotor. The rotor is laminated from the radially inner side to the radially outer side in the order of a permanent magnet layer, a protective layer made of a metal member, and a filament winding layer around which a fiber member is wound.

  The protective layer has a bulging portion that bulges outward in the axial direction from both axial ends of the filament winding layer, and abutting that protrudes outward in the radial direction from the bulging portion and whose outer end surface in the axial direction contacts the bearing shaft. And an enlarged diameter portion constituting the surface.

  Moreover, it is preferable that a fiber member is a nonelectroconductive fiber member.

  Further, the protective layer is provided with a concave or convex first step portion on the axially outer end surface of the enlarged diameter portion, and on the axial end surface of the bearing shaft, the first step portion is coupled to the first step portion by fitting. Two stepped portions are preferably provided.

  Furthermore, it is preferable that the centrifugal compressor has a thrust bearing structure that maintains the axial position of the bearing shaft.

  The rotary shaft unit preferably includes a tension shaft that integrally holds the impeller, one bearing shaft, the rotor, and the other bearing shaft on the same axis.

  Furthermore, it is preferable that a diameter-expanded part is diameter-expanded continuously or intermittently radially outward toward the axially outward direction.

  In the present invention, the filament winding layer in which the fiber member is wound is provided on the outer side in the radial direction of the protective layer made of the metal member. For this reason, in the filament winding layer, heat generation due to eddy current can be prevented. On the other hand, the protective layer is separated from the teeth portion of the stator by the filament winding layer. Therefore, the protective layer can reduce the amount of heat generated due to the eddy current due to the magnetic field fluctuation from the tooth portion.

  Further, the axially outer end surface provided in the enlarged diameter portion of the protective layer constitutes an abutting surface that comes into contact with the bearing shaft. As a result, the heat generated by the eddy current generated in the protective layer is easily and reliably pulled from the abutting surface, and the heat transfer to the permanent magnet layer is suppressed to prevent irreversible demagnetization of the permanent magnet layer. it can.

  Furthermore, the abutting surface provided in the enlarged diameter portion of the protective layer constitutes the outer peripheral portion of the rotor, and the axial strength is maintained by this outer peripheral portion. For this reason, compared with what has a shaft structure in the center of a rotor, axial strength improves and it becomes possible to improve resonance strength favorably.

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 principal part sectional explanatory drawing of the rotating shaft unit which comprises the said centrifugal compressor. FIG. 4 is a sectional view of the centrifugal compressor taken along line IV-IV in FIG. 2. It is a perspective explanatory view of a thrust air bearing constituting the centrifugal compressor. FIG. 6 is a cross-sectional explanatory view taken along the line VI-VI in FIG. 5 of the thrust air bearing. It is principal part cross-sectional explanatory drawing of the rotating shaft unit which comprises the 2nd Embodiment of this invention. It is explanatory drawing of the supercharger for fuel cells 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 on an outer periphery of an annular permanent magnet (permanent magnet layer) 16 and the permanent magnet 16, and accommodates the permanent magnet 16 (for example, shrink fit). And a bearing shaft having the same diameter as the rotor 20 and provided at both axial ends of the rotor 20. 22 and 24, and an impeller 26 provided at an axial end opposite to the rotor 20 side of the bearing shaft 22. The length of the filament winding layer 19 in the axial direction (arrow A direction) is preferably set to be the same as the length of the permanent magnet 16 in the axial direction.

  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 relieving a thrust force generated in the arrow A1 direction when the rotary shaft unit 14 rotates. As shown in FIG. 1, the canceller mechanism 34 includes a canceller disk 38 that is slidable in the direction of the arrow A within the pressurizing chamber 36. Air generated by the rotation of the impeller 26 flows into the pressurizing chamber 36 through the passage 40.

  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. A plurality of cooling water flow paths 48 are formed around the outer periphery of the stator 42.

  The protection ring 18 constituting the rotor 20 is required to have high rigidity, and specifically, is constituted by a nickel-based superalloy, for example, Inconel (trade name of Special Metal Co.).

  The protective ring 18 is formed of a material having a high electrical resistivity, and the radial thickness of the protective ring 18 is set to be equal to or less than the skin depth of the eddy current and the thickness capable of ensuring the strength not to resonate. Is done. The depth S of the eddy current is obtained from S = √2ρ / ωμ. Here, ρ is resistivity, μ is the transmittance of the conductor, and ω is the angular frequency.

  The filament winding layer 19 is configured by winding a fiber member around the outer peripheral surface of the protective ring 18. The fiber member is a non-conductive fiber member. For example, in addition to glass fiber, synthetic fiber such as polyparaphenylene benzobisoxazole can be used.

  For example, conductive carbon fibers may be used as the fiber member. This is because heat can be drawn from the abutting surface 18b (described later) on the surface of the rotor 20 by eddy current.

  As shown in FIG. 3, the protective ring 18 has a bulging portion 18a that bulges outward in the axial direction from both axial ends of the filament winding layer 19, and projects radially outward from the bulging portion 18a. The outer end surface has a diameter-expanded portion 18c constituting an abutting surface 18b that contacts the bearing shafts 22 and 24. The protective ring 18 is provided with a concave (or convex) stepped portion (first stepped portion) 18d on the axially outer end face of the enlarged diameter portion 18c.

  As shown in FIG. 2, the bearing shaft 22 has a cylindrical portion 22 a that is open at one end in the axial direction and a bottom portion (second step portion) 22 b that protrudes 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 (second stepped portion) 24b protruding radially inward at the other axial end.

  As shown in FIGS. 2 and 3, the bottom portion 22 b of the bearing shaft 22 is coaxially fitted to one step portion 18 d of the protective ring 18, and the bottom portion 24 b of the bearing shaft 24 is the other portion of the protective ring 18. It fits coaxially to the stepped portion 18d. 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 that holds the bearing shafts 22, 24 facing the outer peripheral surfaces of the bearing shafts 22, 24 is provided (see FIGS. 1 and 2). 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. A thrust bearing structure is obtained by the thrust air bearing 54 and the canceller mechanism 34.

  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. 4, 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. 5, 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. 6, 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 each level | step-difference part 18d of the protection ring 18 (inlay structure).

  In the casing 12, as shown in FIG. 1, a refrigerant flow passage 70 is formed between the protective ring 18 constituting the motor unit 46 and the stator 42. The inlet side of the flow passage 70 and the passage 40 of the canceller mechanism 34 communicate with the compressor outlet 72 of the centrifugal compressor 28. The air compressed by the rotation of the impeller 26 is blown from the compressor outlet 72 to the inlet side of the flow passage 70 and the passage 40 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 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.

  A part of the air sucked by the centrifugal compressor 28 is compressed and supplied from the compressor outlet 72 to the flow passage 70 in the casing 12. The cooling air that passes through the flow passage 70 and cools 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 72 to the pressurizing chamber 36 through the passage 40 constituting the canceller mechanism 34. Accordingly, a pressing force is applied to the canceller disk 38 disposed in the pressurizing chamber 36 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.

  In this case, in the first embodiment, the filament winding layer 19 in which the fiber member is wound is provided on the outer side in the radial direction of the protective ring 18 made of a metal member. For this reason, the filament winding layer 19 can prevent heat generation due to eddy currents.

  On the other hand, the protective ring 18 is separated from the teeth portion (not shown) of the stator 42 by the filament winding layer 19. Therefore, the protective ring 18 can reduce the amount of heat generated due to eddy currents due to magnetic field fluctuations from the tooth portion.

  Further, as shown in FIG. 3, both the enlarged diameter portions 18 c of the protection ring 18 are configured with abutting surfaces 18 b that contact the bearing shafts 22 and 24. As a result, heat generated by the eddy current generated in the protective ring 18 is easily and reliably pulled from the abutting surface 18b to the bearing shafts 22 and 24. For this reason, the heat transfer to the permanent magnet 16 is suppressed, and the effect that the irreversible demagnetization of the permanent magnet 16 can be prevented is obtained.

  Furthermore, the abutting surface 18b provided in the enlarged diameter portion 18c of the protective ring 18 constitutes the outer peripheral portion of the rotor 20, and the outer peripheral portion maintains the axial strength. Therefore, there is an advantage that the shaft strength is improved and the resonance strength can be improved satisfactorily as compared with the rotor 20 having the shaft structure.

  In the first embodiment, since the protective ring 18 is formed of a material having a high electrical resistivity, the generation of eddy current is effectively reduced. Moreover, the thickness of the protective ring 18 in the radial direction is set to be equal to or smaller than the skin depth of the eddy current and equal to or greater than the thickness capable of ensuring the strength that does not resonate. Thereby, the eddy current generated in the protective ring 18 can be reduced and the resonance strength of the rotor 20 can be ensured.

  Further, the length of the filament winding layer 19 in the axial direction is set to be the same as the length of the permanent magnet 16 in the axial direction, and the bulging portions 18 a of the protective ring 18 are formed from both axial ends of the filament winding layer 19. It bulges outward in the axial direction. Therefore, the resonance strength of the rotor 20 can be easily improved while maintaining the eddy current reduction of the permanent magnet 16 and the heat absorption effect.

  Furthermore, the axial end portion 26a of the impeller 26 is coaxially fitted to the cylindrical portion 22a of the bearing shaft 22 (inlay structure), while the bearing shafts 22 and 24 are protected by the bottom portions 22b and 24b, respectively. It fits coaxially to each step 18d of the ring 18 (inlay structure). For this reason, the joining and positioning operations of the entire rotary shaft unit 14 are simplified at a stroke.

  An impeller 26 and a canceller mechanism 34 are provided at both axial ends of the rotor 20. Thereby, the heat generated in the protective ring 18 can be released to the impeller 26 and the canceller mechanism 34 from both end faces of the rotor 20. In addition, bearing shafts 22 and 24 are provided at both ends of the rotor 20, and heat generated in the protective ring 18 can be released to the bearing shafts 22 and 24 from the respective abutting surfaces 18b.

  Further, the bearing shaft 22, the rotor 20, and the bearing shaft 24 are arranged in this order from the impeller 26 side on the tension shaft 30, and these are integrally held by a fixing member 32 that is screwed to the tension shaft 30. Therefore, the rotor 20 and the bearing shafts 22 and 24 can be made into an integral shaft structure.

  FIG. 7 is a cross-sectional explanatory view of a main part of a rotary shaft unit 82 constituting a centrifugal compressor (supercharger) 80 according to the second embodiment of the present invention.

  In addition, the same referential mark is attached | subjected to the component same as the rotating shaft unit 14 which comprises the centrifugal compressor 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  The rotary shaft unit 82 includes a rotor 84, and the rotor 84 is provided on the outer periphery of the permanent magnet 16, the permanent magnet 16, and a cylindrical protective ring (protective layer) 86 that houses the permanent magnet 16 and a filament. It is constituted by a winding layer 19.

  The protection ring 86 has a bulging portion 86a that bulges outward in the axial direction from both axial ends of the filament winding layer 19, and projects radially outward from the bulging portion 86a. 24 and an enlarged diameter portion 86c constituting an abutting surface 86b in contact with 24.

  The diameter-expanded portion 86c continuously expands radially outward toward the axially outward direction, so that the end surface shape around which the fiber member constituting the filament winding layer 19 is wound is a right-angled shape (first implementation). Form) to taper shape 88. Instead of the tapered shape 88, the diameter may be increased stepwise outward in the radial direction toward the axially outward direction.

  In the second embodiment configured as described above, since the enlarged-diameter portion 86c has the tapered shape 88, when the abutting force acts on the abutting surface 86b, the abutting force acts on the entire protective ring 86. As a result, stress is not concentrated.

  Therefore, in the second embodiment, the same effect as in the first embodiment can be obtained, and the protective ring 86 has an effect that the abutting strength is improved satisfactorily. In addition, the taper shape 88 has an advantage that a wide range of heat sinking paths can be secured and the cooling performance is easily improved.

DESCRIPTION OF SYMBOLS 10, 80 ... Centrifugal compressor 12 ... Casing 14, 82 ... Rotating shaft unit 16 ... Permanent magnet 16a, 16b ... End surface 18, 86 ... Protection ring 19 ... Filament winding layer 18a, 86a ... Swelling part 18b, 86b ... Thing Contact surface 18c, 86c ... Diameter-expanded portion 18d ... Stepped portion 20 ... Rotor 22, 24 ... Bearing shaft 22a, 24a ... Cylindrical portion 22b, 24b ... Bottom portion 26 ... Impeller 30 ... Tension shaft 32 ... Fixing member 34 ... Canceller mechanism 36 ... pressurizing chamber 38 ... canceller disk 40 ... passage 42 ... stator 46 ... motor part 50 ... foil type gas bearings 52a, 52b ... journal air bearing 54 ... thrust air bearings 56A, 56B ... ring member 56a ... inner peripheral surface 58, 66 ... Bump foil 60, 68 ... Top foil 70 ... Distribution Road

Claims (6)

A rotary shaft unit having an impeller at least at one end;
A stator provided in a casing in which the rotary shaft unit is housed, and facing a peripheral surface of the rotary shaft unit;
A centrifugal compressor comprising:
The rotating shaft unit includes a cylindrical rotor,
Bearing shafts having the same diameter as the rotor and disposed at both axial ends of the rotor;
With
The rotor is laminated from the radially inner side to the radially outer side in the order of a permanent magnet layer, a protective layer made of a metal member, and a filament winding layer around which a fiber member is wound,
The protective layer has a bulging portion that bulges outward in the axial direction from both axial ends of the filament winding layer;
A diameter-enlarging portion that protrudes outward in the radial direction from the bulging portion, and that forms an abutment surface in which an axially outer end surface contacts the bearing shaft;
A centrifugal compressor characterized by comprising:   2. The centrifugal compressor according to claim 1, wherein the fiber member is a non-conductive fiber member. The centrifugal compressor according to claim 1 or 2, wherein the protective layer is provided with a concave or convex first step portion on the axially outer end surface of the enlarged diameter portion,
The centrifugal compressor is characterized in that a second stepped portion coupled to the first stepped portion by fitting is provided on an axial end surface of the bearing shaft.   The centrifugal compressor according to any one of claims 1 to 3, further comprising a thrust bearing structure that holds an axial position of the bearing shaft.   5. The centrifugal compressor according to claim 1, wherein the rotary shaft unit integrally and coaxially holds the impeller, one of the bearing shafts, the rotor, and the other bearing shaft. A centrifugal compressor comprising a tension shaft.   The centrifugal compressor according to any one of claims 1 to 5, wherein the diameter-expanding part continuously or intermittently expands radially outward toward the axially outward direction. Features a centrifugal compressor.

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