JP2013099222A - Rotor and rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor which can improve cooling performance of a shaft core cooling structure typed rotor shaft facing a rotor core formed by rotatingly laminating magnetic steel sheets.SOLUTION: A rotor 14 of a rotary electric machine comprises: a rotor core 15 which is formed by rotatingly laminating magnetic steel sheets, and includes a shaft hole 30 in the center thereof; and a rotor shaft 28 which is inserted and fixed to the shaft hole 30 of the rotor core 15 and includes a passage 32 therein through which cooling medium flows. Cutting or broaching is applied to an inner circumference of the shaft hole of the rotor core 15 to uniformize contact condition between the inner circumference of the shaft hole 30 of the rotor core 15 and an outer circumference surface of the rotor shaft 28 at least in the axial direction.

Description

  The present invention relates to a rotor including a rotor core formed by rolling a magnetic plate material, and more particularly to a rotor that cools a rotor core with a cooling medium supplied to a rotor shaft and a rotating electrical machine including the rotor.

  2. Description of the Related Art Conventionally, a rotating electrical machine having a rotor with a built-in permanent magnet is known. In such a rotating electric machine, if the temperature of the rotor core rises due to the iron loss of the rotor, etc., the permanent magnet may cause irreversible demagnetization and the torque output may decrease, so cooling from the rotor shaft to the rotor core Cooling by supplying a medium (for example, cooling oil) is performed.

  For example, Japanese Patent Laying-Open No. 2009-55737 (Patent Document 1) discloses a rotor in which refrigerant is uniformly supplied in the circumferential direction of a rotor core and a rotating electrical machine including the rotor. In this rotor, the rotor core is configured by laminating a first electromagnetic steel plate and a second electromagnetic steel plate in the axial direction, the first electromagnetic steel plate has a hole that constitutes a refrigerant passage, and the second electromagnetic steel plate is a first electromagnetic steel plate. It describes that it has a hole part which forms a refrigerant passage while being formed in a position shifted in the circumferential direction with respect to the hole part.

  Japanese Patent Application Laid-Open No. 2007-104878 (Patent Document 2) discloses a stator core formed by laminating a plurality of electromagnetic steel sheets in a gap formed by surface roughness between the laminated electromagnetic steel sheets. It is described that an insulating material (for example, insulating oil) having a higher thermal conductivity than that is filled.

  Further, JP 2002-199632 A (Patent Document 3) is not configured to supply and cool a cooling medium, but has a structure in which a rotor core formed by stacking steel plates and a rotor shaft do not directly contact each other, It is described that a material having high thermal conductivity is filled between the rotor core and the rotor shaft, and heat generated in the rotor core is released to the rotor shaft.

JP 2009-55737 A JP 2007-104878 A JP 2002-199632 A

  By the way, in a rotor in which a rotor core constituted by laminating electromagnetic steel plates is fixed on a rotor shaft, a cooling medium is not supplied from the rotor shaft to the rotor core, but is caused to flow through the cooling medium in the rotor shaft. In some cases, the rotor core is cooled by dissipating heat transferred from the rotor core to the rotor shaft to the cooling medium in the refrigerant passage. In this case, it is important for improving the cooling performance of the rotor core that the inner peripheral portion of the shaft hole formed in the rotor core and the outer peripheral surface of the rotor shaft are in contact with each other without a gap.

  However, when an integrated rotor core is formed by so-called rolling, in which each of the punched annular magnetic steel sheets is laminated while shifting the circumferential position, a minute amount is formed between the inner circumference of the rotor core shaft hole and the rotor shaft due to the variation in lamination. A gap is generated, which causes a decrease in the cooling performance of the rotor core by the cooling medium flowing in the rotor shaft.

  The objective of this invention is providing the rotor which can improve the cooling performance by the rotor shaft of an axial core cooling structure with respect to the rotor core comprised by the roll over of an electromagnetic steel plate, and a rotary electric machine provided with the same.

  A rotor of a rotating electrical machine according to the present invention is configured by rolling a magnetic steel sheet, and has a rotor core having a shaft hole in the center, and a passage inserted into and fixed to the shaft hole of the rotor core and through which a cooling medium flows. And a process for making the contact state between the inner periphery of the shaft hole of the rotor core and the outer peripheral surface of the rotor shaft at least in the axial direction applied to the inner periphery of the shaft hole of the rotor core after the rolling. is there.

  In the rotor of the rotating electrical machine according to the present invention, the processing of the inner periphery of the shaft hole may be a cutting process that improves the roundness of the cylindrical inner peripheral surface of the shaft hole. This cutting process is preferably broaching.

  Further, in the rotor of the rotating electrical machine according to the present invention, the processing of the inner periphery of the shaft hole is broaching or punching that forms a plurality of grooves at intervals in the circumferential direction on the inner periphery of the shaft hole. A convex portion formed between the plurality of groove portions by being tightly fitted to the rotor shaft may be pressed against the outer peripheral surface of the rotor shaft.

  Furthermore, in the rotor of the rotating electrical machine according to the present invention, the processing of the inner periphery of the shaft hole is a gap generated due to stacking variation due to rolling of the electromagnetic steel sheet between the inner periphery of the shaft hole of the rotor core and the outer peripheral surface of the rotor shaft. In addition, it may be a process of filling a filler having a higher thermal conductivity than air.

  In this case, in the rotor of the rotating electrical machine according to the present invention, a permanent magnet may be embedded in the rotor core, and the filler may be filled in the gap at the same time as injection of a mold resin for fixing the permanent magnet. .

  A rotating electrical machine according to another aspect of the present invention includes a rotor having any one of the above-described configurations.

  According to the rotor of the rotating electrical machine and the rotating electrical machine including the same according to the present invention, the processing for making the contact state between the inner periphery of the shaft hole of the rotor core and the outer peripheral surface of the rotor shaft at least uniform in the axial direction is described above. Since it is applied to the inner circumference of the rotor core after rolling, the thermal conductivity from the rotor core to the rotor shaft is reduced at the gap portion formed between the rotor core and the rotor shaft due to stacking variations due to rolling of the electrical steel sheets. Can be improved. Therefore, it is possible to improve the cooling performance of the rotor shaft core cooling structure in which the electromagnetic steel sheets are rolled.

1 is an axial sectional view of a rotating electrical machine including a rotor according to an embodiment of the present invention. It is an axial sectional view of the rotor in FIG. It is a figure which shows the axial direction end surface of a rotor core. It is an expanded sectional view which shows a mode that it has arisen in the clearance gap between a rotor core and a rotor shaft by the lamination | stacking dispersion | variation by rolling of an electromagnetic steel plate. It is a fragmentary sectional view of a rotor core which shows a mode that cutting was performed to a shaft hole inner circumference of a rotor core. It is the same figure as FIG. 3 which shows a mode that the several groove | channel was formed in the inner peripheral part of the shaft hole of a rotor core by broaching. It is a figure which shows a mode that the filling material with high heat conductivity was filled into the clearance gap between a rotor core and a rotor shaft.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like. In addition, when a plurality of embodiments and modifications are included in the following, it is assumed from the beginning that these characteristic portions are used in appropriate combinations.

  FIG. 1 is a cross-sectional view along the axial direction of a rotating electrical machine 10 including the rotor structure of the present embodiment. As shown in FIG. 1, the rotating electrical machine 10 includes a stator 12 and a rotor 14. A radial gap G is provided between the stator 12 and the rotor 14 so that they are not in contact with each other.

  The stator 12 includes a stator core 13 made of a magnetic material having a cylindrical shape, and a stator coil 16 wound around a plurality of teeth portions protruding from the inner peripheral portion of the stator core 13. The stator core 13 is configured, for example, by laminating a plurality of electromagnetic steel plates each punched into a substantially annular shape in the axial direction and integrally connecting them by caulking or the like. However, the stator core 13 may be configured by arranging a plurality of divided cores made of dust cores in an annular shape and fastening them from the outer periphery with a cylindrical case.

  Stator coil 16 includes an in-slot portion (not shown) inserted and disposed between the tooth portions, and coil end portions 16a and 16b protruding outward from the axial end surface of stator core 13. Each of the coil end portions 16a and 16b is formed in a substantially annular shape when viewed from the axial direction.

  The stator 12 including the stator core 13 and the stator coil 16 is accommodated in the housing 20. The housing 20 includes a bottomed cylindrical portion 22 and a cover portion 24 attached to cover one end opening of the bottomed cylindrical portion 22. The bottomed cylindrical portion 22 of the housing 20 is fixed on the outer peripheral surface of the stator core 13 by a method such as press fitting or shrink fitting. In the housing 20, bearing members 26 are attached to a bottom portion 23 that forms a disk shape of the bottomed cylindrical portion 22 and a cover portion 24.

  The rotor 14 disposed on the inner peripheral side of the stator core 13 includes a rotor core 15 made of a cylindrical magnetic body, and a rotor shaft 28 that extends through the center of the rotor core 15 in the axial direction. The rotor core 15 is formed by laminating a large number of electromagnetic steel sheets punched and processed in a substantially disc shape, respectively, and connecting them together by caulking or the like. Further, the rotor core 15 has substantially the same axial length as the stator core 13, and the axial end faces are arranged substantially flush with each other.

  Both end portions of the rotor shaft 28 extend to the outside of the housing 20 while being rotatably supported by bearing members 26 fixed to the bottomed cylindrical portion 22 and the cover portion 24 of the housing 20. A refrigerant passage 32 (see FIG. 2) extending along the rotation center axis is formed inside the rotor shaft 28.

  The cooling medium supplied from one end of the rotor shaft 28 flows through the refrigerant passage 32 of the rotor shaft 28 and is discharged from the other end of the rotor shaft 28. As the cooling medium, for example, a cooling oil such as ATF is preferably used. In the following description, it is assumed that the cooling medium is a cooling oil, but other cooling mediums may be used as long as the cooling fluid can exhibit good cooling performance for the rotor 14 including the rotor core 15. The cooling oil is circulated and supplied to the rotor shaft 28 via an oil pump and an oil cooler (not shown).

  2 is an axial sectional view of the rotor 14 in FIG. 1, and FIG. 3 is a diagram showing an axial end surface of the rotor core 15.

  As shown in FIGS. 2 and 3, the rotor core 15 formed by rolling an electromagnetic steel plate has a substantially cylindrical shape, and a shaft hole 30 is formed through the center thereof. Two key portions 33 project from the inner peripheral portion of the shaft hole 30 so as to face each other in the radial direction. Correspondingly, a key groove (not shown) is formed on the outer peripheral surface of the rotor shaft 28 so as to extend in the axial direction. As a result, the rotor shaft 28 is inserted into the shaft hole 30 of the rotor core 15 and the key portion 33 is fitted into the key groove, whereby the circumferential position of the rotor core 15 with respect to the rotor shaft 28 is determined.

  In this embodiment, the description has been given on the assumption that the circumferential position of the rotor core 15 on the rotor shaft 28 is determined by the fitting of the key portion 33 and the key groove. However, the present invention is not limited to this. The circumferential position on the rotor shaft 28 may be determined by being fixed by shrink fitting, press fitting, or the like. In this case, although it is not necessary to form a key part in the shaft hole 30 of the rotor core 15, you may use combining key fitting and shrink fitting. Thereby, the connection strength of the rotor core 15 with respect to the rotor shaft 28 is further strengthened, and the torque transmission performance is improved.

  As shown in FIG. 2, the rotor 14 further includes two end plates 42 disposed on the rotor core 15 on both sides in the axial direction. The end plate 42 has a disk shape having substantially the same outer diameter as the rotor core 15, and the rotor shaft 28 is provided through the center thereof.

  The end plate 42 is preferably formed from a nonmagnetic material (eg, aluminum, aluminum alloy, ceramic, resin, etc.). Thereby, the short circuit or leakage of the magnetic flux in the axial direction edge part of permanent magnet 36a, 36b can be suppressed effectively. The end plate 42 also has a function of preventing the permanent magnets 36a and 36b from protruding from the rotor core 15 in the axial direction.

  The end plates 42 on both sides in the axial direction sandwich the rotor core 15 in a state in which the rotor core 15 is pressed in the axial direction by fixing the fixing member 31, which is an annular metal member, on the rotor shaft 28 by caulking, welding, or the like. Fixed. Thus, the axial positions of the rotor core 15 and the end plate 42 with respect to the rotor shaft 28 are determined. Similarly to the rotor core 15, the end plate 42 has a circumferential position with respect to the rotor shaft 28 by fitting a key portion (not shown) formed at the edge of the inner peripheral hole into the key groove of the rotor shaft 28. It may be decided.

  In the above description, it has been described that both axial sides of the rotor core 15 and the end plate 42 are fixed by the fixing members 31. However, the present invention is not limited to this, and a flange portion protrudes from the outer periphery of the rotor shaft 28 and ends. Positioning on one side in the axial direction may be performed by stopping the end face of the plate.

  As shown in FIG. 3, the rotor core 15 is provided with a plurality of magnetic poles 34 at intervals in the circumferential direction. In the present embodiment, an example is shown in which eight magnetic poles 34 are provided at equal intervals in the circumferential direction. Two magnetic poles 34 adjacent in the circumferential direction form one magnetic pole pair (for example, N pole and S pole), and a total of four magnetic pole pairs are included.

  Two permanent magnets 36 a and 36 b are embedded in each magnetic pole 34. The permanent magnets 36a and 36b and the rotor core 15 have substantially the same axial length. Further, the permanent magnets 36 a and 36 b are arranged in a substantially V shape that spreads toward the outer peripheral side of the rotor core 15.

  The permanent magnets 36a and 36b are fixed to the rotor core 15 by being inserted into a magnet insertion hole formed in advance in the rotor core 15 from the axial direction and then filled with a molding resin in the pocket portion 38 communicating with the magnet insertion hole. Yes. In FIG. 3, the portion filled with the mold resin is shown darkly.

  Moreover, the rotor core 15 has the space | gap part 40 as a hole penetrated to an axial direction, respectively. The gap 40 is formed in the vicinity of the shaft hole 30 in the inner peripheral side region corresponding to the gap between the magnetic poles 34 in the circumferential direction. In the present embodiment, an example is shown in which eight gaps 40 are formed at equal intervals in the circumferential direction. These gaps 40 play a role such as reducing the weight of the rotor core 15 and forming a substantially arc-shaped q-axis magnetic path region on the inner peripheral side of the magnetic pole 34.

  FIG. 4 is an enlarged cross-sectional view illustrating a state in which a gap is generated between the inner periphery of the shaft hole 30 of the rotor core 15 and the outer peripheral surface of the rotor shaft 28 due to the stacking variation due to the rolling of the electromagnetic steel sheets.

  In the rotor 14 of the present embodiment in which the rotor core 15 is fixed on the rotor shaft 28, cooling oil is caused to flow through the refrigerant passage 32 in the rotor shaft 28, and heat transmitted from the rotor core 15 to the rotor shaft 28 is passed through the refrigerant passage 32. A so-called shaft core cooling structure is adopted in which the rotor core 15 is cooled by passing it to the cooling oil.

  However, since the rotor core 15 made of a steel sheet laminate is formed by laminating the punched electromagnetic steel sheets in the axial direction while rolling, the inner peripheral portion of the shaft hole 30 of the rotor core 15 and the rotor shaft are caused by the variation in lamination. The degree of contact with the shaft 28 is not uniform in the axial direction, and a minute gap 44 may be formed between the inner peripheral portion of the shaft hole 30 and the rotor shaft 28. If it does so, the heat transfer from the rotor core 15 to the rotor shaft 28 will be inhibited by the presence of an air layer having a low thermal conductivity, and this will cause the cooling performance of the rotor core 15 to be reduced.

  Therefore, in the rotor 14 of the present embodiment, the contact state between the inner periphery of the shaft hole 30 and the outer peripheral surface of the rotor shaft is made uniform at least in the axial direction by processing the shaft hole 30 of the rotor core 15 after rolling. Thereby, it was decided to improve the decrease in thermal conductivity in the gap portion formed between the rotor core 15 and the rotor shaft 28 due to the stacking variation due to the rolling of the electromagnetic steel sheets. Next, processing for the shaft hole 30 of the rotor core 15 will be described.

  In the first aspect of the present embodiment, as shown in FIG. 5, the shaft hole 30 of the rotor core 15 has a cylindrical inner periphery of the shaft hole 30 of the rotor core 15 that is integrally formed by rolling the electromagnetic steel plates. Cutting is performed so as to eliminate the stacking variation and increase the roundness of the hole edge excluding the key portion 33. For example, broaching is suitable for this cutting, but other cutting may be used. By cutting in this way, the inner periphery of the shaft hole 30 can be brought into contact with the outer periphery of the rotor shaft 28 without any gap in the axial direction and the circumferential direction. Therefore, the cooling performance of the rotor core 15 by the rotor shaft 28 having the shaft oil cooling structure can be improved. In consideration of performing such cutting, shaft holes that are punched into each electromagnetic steel sheet may be formed to have a slightly smaller diameter than the rotor shaft 28.

  In the second mode of the present embodiment, as shown in FIG. 6, a plurality of grooves 31a are formed by broaching on the inner peripheral edge of the shaft hole 30 of the rotor core 15, and the rotor core 15 is tightly fitted and press-fitted. It was made to fix on the rotor shaft 28 by etc. Thereby, the convex part 31b located between the several groove parts 31a formed in the inner periphery of the shaft hole 30 can be uniformly press-contacted over the outer peripheral surface of the rotor shaft 28 over an axial direction, and the lamination | stacking dispersion | variation of an electromagnetic steel plate It is possible to improve the decrease in thermal conductivity due to the gap between the rotor core 15 and the rotor shaft 28. Therefore, the cooling performance of the rotor core 15 by the rotor shaft 28 having the shaft oil cooling structure can be improved. Further, according to this aspect, torque transmission between the rotor core 15 and the rotor shaft 28 can be shared by the entire circumference of the shaft hole 30 without being concentrated only on the key portion 33, and there is an advantage that torque transmission performance is improved. Further, according to this aspect, it is possible to reduce the press-fitting load when the rotor core 15 is fixed to the rotor shaft 28 by press-fitting, and to relieve the radially outer pressing force that acts on the rotor core 15 from the rotor shaft 28 after press-fitting. There is also an advantage that deformation of the rotor core 15 can be suppressed. In the above description, the groove 31a is formed by broaching. However, the present invention is not limited to this, and the groove 31a may be formed at the time of punching each electromagnetic steel sheet constituting the rotor core 15.

  Further, in the third aspect of the present embodiment, as shown in FIG. 7, the gap 44 between the rotor core 15 and the rotor shaft 28 is filled with a filler 46 having a higher thermal conductivity than air. Yes. Thereby, it can improve that heat conductivity falls by the clearance gap between the rotor core 15 and the rotor shaft 28 by the lamination | stacking dispersion | variation in an electromagnetic steel plate. Therefore, the cooling performance of the rotor core 15 by the rotor shaft 28 having the shaft oil cooling structure can be improved.

  In addition, it can be said that the filling process of this aspect is a process which contacts the inner periphery of the shaft hole 30 of the rotor core 15 directly or indirectly via a filler in the axial direction and the circumferential direction. Further, the filling process of the filler may be performed by applying a filler 46 such as an adhesive to the inner periphery of the shaft hole 30 or the outer peripheral surface of the rotor shaft 28 before inserting the shaft.

  In the third aspect, the filler 46 may fulfill the function of bonding and fixing each electromagnetic steel plate constituting the rotor core 15 and the rotor shaft 28 by curing. Thereby, the connection strength of the rotor core 15 with respect to the rotor shaft 28 increases, so that the entire inner peripheral portion other than the key portion 33 in the shaft hole 30 of the rotor core 15 can be effectively functioned as a torque transmission portion for the rotor shaft 28. . Therefore, torque transmission performance from the rotor core 15 to the rotor shaft 28 can be enhanced. Of course, this is particularly effective when the rotor core 15 is fixed to the rotor shaft 28 in a connected state (for example, shrink fitting, press-fitting, etc.) that does not have a fitting between the key portion and the key groove.

  The filler 46 may be filled with the same mold resin material at the same time as the mold resin is injected to fix the permanent magnets 36 a and 36 b to the rotor core 15. In this way, it is not necessary to provide a special filling step of the filler 46, and the number of manufacturing steps is not increased.

  The rotor according to the present invention is not limited to the above-described embodiment and its modifications, and various modifications and improvements can be made within the scope of the matters described in the claims.

  For example, you may combine the filler 46 in a 3rd aspect with a 2nd aspect. That is, in the second aspect, the filling material 46 may be filled into the groove 31a formed on the inner periphery of the shaft hole 30 by broaching. Thereby, the thermal conductivity from the rotor core 15 to the rotor shaft 28 is further improved, and the cooling performance by the rotor shaft having the shaft oil cooling structure can be further improved.

  In the above embodiment, the cooling oil is flowed only into the rotor shaft 28 to indirectly cool the rotor core 15. However, the present invention is not limited to this, and the cooling oil is supplied from the rotor shaft to the rotor core. Then, the rotor core may be cooled by causing the cooling oil to directly contact the rotor core to flow.

  Further, the cooling oil is discharged directly from the outer peripheral surface of the rotor shaft or through at least one of the end plate and the rotor core, and scattered in the radial direction by the centrifugal force of the rotating rotor, whereby the inner peripheral side of the coil end portion A cooling oil may be applied to cool the coil and the stator.

  DESCRIPTION OF SYMBOLS 10 Rotating electrical machine, 12 Stator, 13 Stator core, 14 Rotor, 15 Rotor core, 16 Stator coil, 16a, 16b Coil end part, 18 Electrical steel plate, 20 Housing, 22 Bottomed cylindrical part, 23 Bottom part, 24 Cover part, 26 Bearing member , 28 Rotor shaft, 30 Shaft hole, 31 Fixing member, 31a Groove, 31b Protruding part, 32 Refrigerant passage, 33 Key part, 34 Magnetic pole, 36a, 36b Permanent magnet, 38 Pocket part, 40 Air gap part, 42 End plate, 44 Gap, 46 filler, G gap.

Claims (6)

A rotor core having a shaft hole in the center, which is formed by rolling electrical steel sheets;
A rotor shaft that is inserted and fixed in the shaft hole of the rotor core and has a passage through which a cooling medium flows, and
Processing that makes the contact state between the inner periphery of the shaft hole of the rotor core and the outer peripheral surface of the rotor shaft uniform at least in the axial direction is applied to the inner periphery of the shaft hole of the rotor core after the rollover.
Rotor for rotating electrical machines. The rotor of the rotating electrical machine according to claim 1,
The processing of the inner periphery of the shaft hole is a rotor of a rotating electrical machine that is a cutting process that improves the roundness of the cylindrical inner peripheral surface of the shaft hole. The rotor of the rotating electrical machine according to claim 1,
The processing of the inner periphery of the shaft hole is broaching or punching that forms a plurality of grooves at circumferential intervals on the inner periphery of the shaft hole. A rotor of a rotating electrical machine, wherein convex portions formed between the groove portions are pressed against the outer peripheral surface of the rotor shaft. In the rotor of the rotary electric machine according to any one of claims 1 to 3,
The processing of the inner periphery of the shaft hole is a filler having a thermal conductivity higher than that of air in a gap generated due to stacking variation due to the rolling of the electromagnetic steel sheet between the inner periphery of the shaft hole of the rotor core and the outer peripheral surface of the rotor shaft. A rotor of a rotating electrical machine that is a process of filling The rotor of the rotating electrical machine according to claim 4,
A rotor of a rotating electrical machine in which a permanent magnet is embedded in the rotor core, and the filler is filled in the gap simultaneously with injection of a mold resin for fixing the permanent magnet.   A rotating electrical machine comprising the rotor according to any one of claims 1 to 5.

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