JP2010283920A - Rotor structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily suppress generation of eddy currents in internal permanent magnets, and to improve the manufacturing workability. <P>SOLUTION: Rotor structure 10 includes the cylindrical permanent magnet 26; a first protective ring 28 for preventing scattering of the permanent magnet while being provided on the outer periphery of the permanent magnet 26; and a second protective ring 30 that is provided on the outer periphery of the first protective ring 28 and has thermal conductivity and electrical conductivity higher than those of the first protective ring 28. Then, a plurality of grooves 32 are formed in a peripheral direction on the outer periphery of the second protective ring 30, thus a recessed and projected part is provided along an axial direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotor structure that is provided on the inner peripheral side of a ring-shaped stator and rotates by energizing a winding wound around the stator.

  In general, a centrifugal compressor is employed to efficiently supply 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. 6, 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 Inconel (trade name of Special Metal Co., Ltd.) is provided on the outer periphery of the permanent magnet 2, and a plurality of grooves 4 are provided on the outer periphery of the protective ring 3 at equal intervals in the axial direction and in the circumferential direction. Is provided. The groove 4 is provided with a protective layer 5 around which a nonconductive film made of carbon fiber or the like is wound.

  As a result, the protective ring 3 made of Inconel is reduced in eddy current loss because the portion of the groove 4 is thin, while the protective ring 3 made of Inconel is exposed on the surface of the rotor, so that heat dissipation is improved. .

JP 2008-219965 A

  However, in Patent Document 1 described above, although the thickness of the protective ring 3 can be reduced, the penetration of magnetic flux into the permanent magnet 2 arranged inside the protective ring 3 cannot be suppressed. Thereby, there exists a problem that the eddy current loss in the permanent magnet 2 increases.

  Moreover, since the protective ring 3 is made of a material having low thermal conductivity such as Inconel, it is difficult to release the heat generated by the permanent magnet 2 to the surroundings. Furthermore, since Inconel has high strength, it takes time to perform the cutting work for forming the plurality of grooves 4 on the outer periphery of the protective ring 3, and there is a problem that the manufacturing workability is lowered.

  The present invention solves this type of problem, and provides a rotor structure capable of satisfactorily suppressing the generation of eddy currents in an internal permanent magnet and improving manufacturing workability. Objective.

  The present invention relates to a rotor structure which is provided on the inner peripheral side of a stator arranged in an annular shape and rotates by energizing a winding wound around the stator.

  The rotor structure is provided with a cylindrical permanent magnet, a first protective ring for preventing permanent magnet scattering provided on the outer periphery of the permanent magnet, and an outer periphery of the first protective ring. A second protective ring having high thermal conductivity and high electrical conductivity. And the uneven | corrugated | grooved part is provided in the outer periphery of the 2nd protection ring along the axial direction by forming the some groove part in the circumferential direction.

  In the rotor structure, a refrigerant flow passage is preferably formed between the stator and the second protective ring.

  Further, in this rotor structure, a stepped portion projecting in an annular shape is formed on the outer peripheral side on the end face of the first protective ring, and the stepped portion is axially outward from a position corresponding to the end of the stator. On the other hand, the second protective ring is preferably provided with a convex portion having a guide surface that is inclined along the flow direction of the refrigerant at a portion corresponding to the step portion in the radial direction.

  Furthermore, this rotor structure is preferably incorporated into a centrifugal compressor having an impeller at least at one end.

  Moreover, it is preferable that the edge part of a 2nd protection ring is connected to an impeller through a heat-transfer member.

  Furthermore, the heat transfer member is preferably a bearing shaft that is rotatably supported by an air bearing.

  Furthermore, it is preferable that the impeller, the bearing shaft, and the first and second protection rings are constrained in the axial direction integrally by the tie shaft with their respective end faces in contact.

  In the present invention, the second protective ring having high thermal conductivity and high conductivity is provided on the outermost periphery of the rotor structure. For this reason, it becomes easy to generate an eddy current concentrated on the second protection ring, and the groove provided on the outer periphery of the second protection ring can reduce the eddy current loss of the second protection ring.

  In addition, since the second protection ring functions as an electromagnetic wave blocking ring, the penetration of magnetic flux into the permanent magnet disposed inside the rotor structure is suppressed, and the occurrence of eddy current loss in the permanent magnet is well suppressed. can do. Thus, heat generation due to eddy current loss is suppressed inside the rotor structure, and high-speed rotation can be easily performed.

  Furthermore, a material having excellent machinability can be used for the second protective ring. Therefore, in the cutting operation for forming the plurality of grooves on the outer periphery of the second protective ring, for example, the cutting time is significantly shortened compared to the cutting operation of Inconel, and the workability is improved at a stroke.

It is a section explanatory view of the electric centrifugal compressor to which the rotor structure concerning a 1st embodiment of the present invention is applied. It is a partial cross section perspective explanatory view of the rotor structure. It is a cross-sectional explanatory view of the rotor structure. It is a schematic perspective explanatory drawing of the rotor structure which concerns on the 2nd Embodiment of this invention. It is a schematic perspective explanatory drawing of the rotor structure which concerns on the 3rd Embodiment of this invention. It is a section explanatory view of the rotor which constitutes the rotary machine currently indicated by patent documents 1.

  As shown in FIG. 1, the electric centrifugal compressor 12 to which the rotor structure 10 according to the first embodiment of the present invention is applied includes a casing 14, and an annular stator 16 is wound in the casing 14. The wire 18 is mounted in a wound state.

  A plurality of cooling water flow paths 20 are formed on the outer peripheral side of the stator 16. The rotor structure 10 according to the first embodiment that rotates by energizing the winding 18 is provided on the inner peripheral side of the stator 16. A scroll 22 is attached to one end of the casing 14, and an impeller 24 is rotatably disposed substantially at the center of the scroll 22.

  As shown in FIGS. 2 and 3, the rotor structure 10 includes a cylindrical permanent magnet 26, a first protective ring 28 for preventing permanent magnets scattered on the outer periphery of the permanent magnet 26, and the first protective ring. And a second protective ring 30 having higher thermal conductivity and higher conductivity than the first protective ring 28.

  The first protective ring 28 is made of a nickel-based superalloy, and for example, Inconel (trade name of Special Metal) is used. The second protective ring 30 has an electromagnetic wave shielding function and is made of, for example, copper or aluminum. On the outer periphery of the second protective ring 30, a plurality of groove portions 32 are formed as parallel grooves in the circumferential direction, whereby uneven portions are provided along the axial direction (arrow A direction).

  As shown in FIG. 3, stepped portions 28 a and 28 b projecting in an annular shape are formed on the outer peripheral side on both axial end surfaces of the first protective ring 28. The step portions 28 a and 28 b protrude outward in the axial direction from positions corresponding to the end portions of the stator 16, that is, from the width dimension H in the arrow A direction of the stator 16.

  The second protective ring 30 has convex portions 36a, 36b having guide surfaces 34a, 34b that are inclined along the refrigerant flow direction, which will be described later, at portions corresponding to the step portions 28a, 28b in the radial direction (arrow B direction). Is provided. The guide surfaces 34a and 34b substantially constitute curved surfaces.

  Bearing shafts (heat transfer members) 38 a and 38 b that are fitted (inlayed) to the step portions 28 a and 28 b of the first protective ring 28 are connected to both ends of the rotor structure 10 in the axial direction. The bearing shafts 38 a and 38 b are in contact with the end surfaces of the first and second protection rings 28 and 30, and are supported by radial bearings 40 a and 40 b provided in the casing 14. The radial bearings 40a and 40b constitute, for example, air bearings (or magnetic bearings).

  As shown in FIG. 1, the bearing shaft 38 a is provided with a flange portion 42, and the flange portion 42 is supported by a thrust bearing 44. The thrust bearing 44 constitutes an air bearing (or magnetic bearing), for example.

  The impeller 24, the bearing shaft 38a, the rotor structure 10, and the bearing shaft 38b are constrained in the axial direction integrally by the tie shaft 46 with their respective end surfaces in contact with each other. The tie shaft 46 is provided with a large diameter portion 48 at an end portion on the impeller 24 side, and a fixing member 52 is attached to the bearing shaft 38b side.

  In the casing 14, a refrigerant flow passage 54 is formed between the second protection ring 30 constituting the rotor structure 10 and the winding 18 (substantially, the stator 16). The inlet side of the flow passage 54 communicates with a cooling pipe 56 that communicates with the scroll 22, and an intercooler 58 is disposed in the cooling pipe 56. The flow passage 54 has an inlet on the bearing shaft 38b side and an outlet on the bearing shaft 38a side.

  In the rotor structure 10, a carbon-based winding structure (reinforcing material) may be wound around the outer periphery of the second protective ring 30 in order to provide axial strength, and heat generated by eddy current loss is absorbed at both ends. A heat transfer structure for transmitting to the bearing shafts 38a and 38b may be provided.

  The operation of the electric centrifugal compressor 12 configured as described above will be described below in relation to the rotor structure 10 according to the first embodiment.

  First, by energizing the winding 18 constituting the electric motor, the permanent magnet 26, the first protection ring 28, and the second protection ring 30 constituting the rotor structure 10 rotate integrally with the tie shaft 46. For this reason, the impeller 24 held by the tie shaft 46 rotates at a relatively high speed, and air is sucked from the atmosphere via the scroll 22.

  The air sucked by the impeller 24 is pressure-fed by the scroll 22 and 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 compressed air sucked by the scroll 22 is cooled by the intercooler 58 through the cooling pipe 56 and then supplied to the flow passage 54 in the casing 14 as cooling air. The cooling air that has cooled the rotor structure 10 through the flow passage 54 is discharged from the bearing shaft 38a side.

  In this case, in the first embodiment, in the rotor structure 10, a first protective ring 28 for preventing permanent magnets is provided on the outer periphery of the permanent magnet 26, and the first protective ring 28 is provided on the outer periphery of the first protective ring 28. A second protective ring 30 having higher thermal conductivity and higher conductivity than the first protective ring 28 is provided. For this reason, eddy currents are easily generated in the second protective ring 30 in a concentrated manner, and eddy current loss of the second protective ring 30 is reduced by the plurality of grooves 32 provided on the outer periphery of the second protective ring 30. The effect of reduction can be obtained.

  In addition, since the second protective ring 30 functions as an electromagnetic wave blocking ring, the penetration of magnetic flux into the permanent magnet 26 disposed inside the rotor structure 10 is suppressed, and eddy current loss occurs in the permanent magnet 26. Can be suppressed satisfactorily. As a result, heat generation due to eddy current loss is suppressed in the rotor structure 10, and high-speed rotation can be easily performed.

  Further, a material having excellent machinability, for example, aluminum can be used for the second protective ring 30. Therefore, in the cutting operation for forming the plurality of groove portions 32 on the outer periphery of the second protective ring 30, the cutting time is significantly shortened compared with the cutting operation of Inconel, and the workability is improved at once.

  Furthermore, in the rotor structure 10, a refrigerant flow passage 54 is formed between the stator 16 and the winding 18 and the second protective ring 30. Therefore, heat generated on the surface of the rotor structure 10, that is, the surface of the second protective ring 30, under the cooling action of the cooling air flowing in the direction of the arrow in FIG. 10 can be taken reliably. This makes it possible to prevent heat from being transmitted to the permanent magnet 26 as much as possible.

  Further, as shown in FIG. 3, stepped portions 28 a and 28 b projecting outward in the width dimension H of the stator 16 are provided at both axial ends of the first protective ring 28, while the second protective ring 30 Convex portions 36a and 36b having guide surfaces 34a and 34b are formed in portions corresponding to the step portions 28a and 28b in the radial direction. Therefore, the cooling air (refrigerant) supplied to the flow passage 54 can be rectified well, and the cooling efficiency of the rotor structure 10 is effectively improved. Moreover, the convex portions 36a and 36b are provided at locations not related to the magnetic flux, and do not affect the drive as the electric motor.

  Here, in the plurality of groove portions 32 provided on the outer periphery of the second protective ring 30, the groove depth is set to be greater than or equal to the depth at which the electromagnetic wave penetrates, and the groove width is less than or equal to a width that can sufficiently suppress eddy current loss. Is set.

  Furthermore, in 1st Embodiment, the rotor structure 10 is integrated in the electric centrifugal compressor 12 which provided the impeller 24 at least at one end. For this reason, it becomes possible to suppress the demagnetization with respect to the heat_generation | fever of the rotor structure 10, and can comprise the centrifugal compressor 12 with which high speed rotation and size reduction are achieved easily.

  Furthermore, the second protective ring 30 is in contact with the impeller 24 via a bearing shaft 38a constituting a heat transfer member at one axial end. Thereby, the heat generated on the surface of the second protective ring 30 can be effectively removed from the bearing shaft 38a to the impeller 24. At this time, since the bearing shaft 38a functions as a heat transfer member, it is not necessary to provide a dedicated heat transfer member, and the configuration can be simplified.

  Further, the impeller 24, the bearing shaft 38a, the rotor structure 10, and the bearing shaft 38b are integrally restrained in the axial direction by the tie shaft 46 so that the outer peripheral portions thereof are in contact with each other. Therefore, by tightening the tie shaft 46, heat can be reliably removed to both axial sides of the rotor structure 10, and eddy current loss (iron loss) of the permanent magnet 26 can be prevented as much as possible.

  FIG. 4 is a schematic perspective view of a rotor structure 70 according to the second embodiment of the present invention.

  Note that the same components as those of the rotor structure 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  In the rotor structure 70, a second protective ring 72 having a higher thermal conductivity and higher conductivity than the first protective ring 28 is provided on the outer periphery of the first protective ring 28. On the outer periphery of the second protective ring 72, an annular groove 74 is formed in a spiral shape, so that an uneven portion is provided along the axial direction.

  In the second embodiment configured as above, the eddy current loss can be reduced by the groove 74 provided on the outer periphery of the second protective ring 72. In addition, since the groove 74 has a spiral shape, the surrounding air can be transferred in the axial direction as the rotor structure 70 rotates. For this reason, heat transfer of ambient air from the second protective ring 72 is promoted, and the cooling efficiency of the second protective ring 72 is further improved.

  Further, by utilizing the reaction force due to air transportation, the thrust force due to the impeller 24 can be relaxed and the thrust bearing 44 can be assisted.

  FIG. 5 is a schematic perspective explanatory view of a rotor structure 80 according to the third embodiment of the present invention.

  In the rotor structure 80, a second protective ring 82 having higher thermal conductivity and conductivity than the first protective ring 28 is provided on the outer periphery of the first protective ring 28. A plurality of groove portions 32 and longitudinal grooves 84 extending in the axial direction are provided on the outer periphery of the second protective ring 82. As a result, the same effects as those of the first embodiment can be obtained, and there is an advantage that the eddy current loss of the second protective ring 82 can be further reduced.

DESCRIPTION OF SYMBOLS 10, 70, 80 ... Rotor structure 12 ... Electric centrifugal compressor 14 ... Casing 16 ... Stator 18 ... Winding 20 ... Cooling water flow path 22 ... Scroll 24 ... Impeller 26 ... Permanent magnet 28, 30, 72, 82 ... Protective ring 28a 28b ... Step part 32, 74 ... Groove part 34a, 34b ... Guide surface 36a, 36b ... Convex part 38a, 38b ... Bearing shaft 40a, 40b ... Radial bearing 42 ... Flange part 44 ... Thrust bearing 46 ... Tie shaft 54 ... Flow passage 56 ... Cooling piping 58 ... Intercooler 84 ... Vertical groove

Claims (7)

A rotor structure that is provided on the inner peripheral side of a stator arranged in an annular shape and that rotates by energizing a winding wound around the stator,
A cylindrical permanent magnet;
A first protective ring for preventing permanent magnet scattering provided on the outer periphery of the permanent magnet;
A second protective ring provided on the outer periphery of the first protective ring, having a higher thermal conductivity and conductivity than the first protective ring;
With
A rotor structure characterized in that a plurality of groove portions are formed in the circumferential direction on the outer periphery of the second protective ring, whereby uneven portions are provided along the axial direction.   The rotor structure according to claim 1, wherein a refrigerant flow passage is formed between the stator and the second protection ring. The rotor structure according to claim 2, wherein a stepped portion projecting in an annular shape is formed on an outer peripheral side of the end face of the first protective ring,
While the stepped portion protrudes axially outward from a position corresponding to the end of the stator,
The rotor structure, wherein the second protection ring is provided with a convex portion having a guide surface that is inclined along a flow direction of the refrigerant at a portion corresponding to the step portion in the radial direction.   The rotor structure according to any one of claims 1 to 3, wherein the rotor structure is incorporated in a centrifugal compressor including an impeller at least at one end.   5. The rotor structure according to claim 4, wherein an end of the second protective ring is connected to the impeller through a heat transfer member.   6. The rotor structure according to claim 5, wherein the heat transfer member is a bearing shaft rotatably supported by an air bearing.   7. The rotor structure according to claim 6, wherein the impeller, the bearing shaft, and the first and second protective rings are axially restrained integrally by a tie shaft with their respective end surfaces in contact with each other. Rotor structure.

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