Rotor of rotary electric machine

Abstract

To provide a rotor of a rotary electric machine which enables suppression of induction voltage in rotation without causing increase of manufacturing costs and deterioration of strength.SOLUTION: A rotor 12 of a rotary electric machine comprises: a rotor core 18 formed by lamination of electromagnetic steel sheets; a rotational shaft inserted into a center of the rotor core 18 and integrated with the rotor core 18; magnet insertion holes 21 formed for every magnetic pole of the rotor core 18 and extending along an axial direction of the rotational shaft; permanent magnets 22 inserted into the magnet insertion holes 21; and air gaps 23 formed by the permanent magnets 22 and the rotor core 18 in the magnet insertion holes 21. The rotor core 18 is provided with: a plurality of pairs of magnet insertion holes 21 adjacent to each other in a circumferential direction of the rotor core 18; bridges formed between the magnet insertion holes 21 adjacent to each other; and clamping bodies inserted into the air gaps 23 and clamping the bridge in the axial direction. The clamping bodies are formed of materials being nonmagnetic and having linear expansion coefficients larger than those of the electromagnetic steel sheets.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rotor for a rotating electrical machine. [Background technology]

[0002] As a conventional technique related to the rotor of a rotating electric machine, for example, a permanent magnet type rotating electric machine disclosed in Patent Document 1 is known. The permanent magnet type rotating electric machine disclosed in Patent Document 1 includes a stator wound with an excitation coil, and a rotor arranged to rotate freely relative to the stator with a predetermined gap, and provided with a permanent magnet. The rotor is provided with a magnetic characteristic variable element (super magnetostrictive element) whose magnetic characteristics change when stress is applied due to the rotation of the rotor, thereby reducing the magnetic flux of the permanent magnet. According to the permanent magnet type rotating electric machine of Patent Document 1, when the rotation speed of the rotor increases, the rotational centrifugal force of the rotor is applied as stress to the magnetic characteristic variable element, which changes the magnetic characteristics of the magnetic characteristic variable element and reduces the magnetic flux of the permanent magnet, thereby suppressing the induced voltage of the permanent magnet type rotating electric machine and preventing the destruction or failure of electronic components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-228077 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the rotor of the permanent magnet type rotating electric machine disclosed in Patent Document 1 can suppress the induced voltage of the permanent magnet type rotating electric machine, there is a problem that the manufacturing cost increases due to the use of expensive magnetic property variable elements. In addition, if the magnetic property variable element deforms during the rotation of the rotor, a gap may occur between the permanent magnet inserted in the rotor and the rotor, which may reduce the strength of the rotor. An example is also disclosed in which a stress adjustment block is provided radially inside the magnetic property variable element, but the need for the stress adjustment block further increases the manufacturing cost.

[0005] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a rotor for a rotating electric machine that makes it possible to suppress induced voltage during rotation without increasing manufacturing costs or reducing strength. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a rotor for a rotating electric machine having a rotor core formed by stacking electromagnetic steel sheets, a rotating shaft inserted through the center of the rotor core and integrated with the rotor core, magnet insertion holes formed for each magnetic pole of the rotor core and extending along the axial direction of the rotating shaft, permanent magnets inserted into the magnet insertion holes, and a gap formed in the magnet insertion hole by the permanent magnets and the rotor core, wherein the rotor core has a plurality of pairs of the magnet insertion holes formed adjacent to each other in the circumferential direction of the rotor core, a bridge is formed between the adjacent gaps, and a clamping body is inserted into the gap and clamps the bridge along the axial direction of the rotating shaft, and the clamping body is formed of a non-magnetic material having a larger linear expansion coefficient than the electromagnetic steel sheets.

[0007] In the present invention, a non-magnetic pressing body is inserted into the gap formed by the permanent magnet and the rotor core, and presses the bridge in the axial direction of the rotating shaft. Since the pressing body is non-magnetic, no leakage of magnetic flux occurs from the pressing body. When the rotation of the rotor increases, the rotor core generates heat due to an increase in iron loss, but since the pressing body has a larger linear expansion coefficient than the electromagnetic steel sheet that constitutes the rotor core, the amount of axial expansion of the pressing body due to heat generation is larger than that of the rotor core. Therefore, the axial stress of the rotor core caused by the pressing body is reduced. When the axial stress of the rotor core caused by the pressing body is reduced, the leakage magnetic flux increases, so that the induced voltage at high rotation can be suppressed. When the rotor rotates slowly, there is almost no heat generation due to iron loss compared to when the rotor rotates quickly, so the rotor core hardly expands in the axial direction, and the axial stress of the rotor core caused by the pressing body is maintained. As a result, the leakage magnetic flux in the rotor core is suppressed, and a high torque of the rotor can be obtained.

[0008] In the rotor for the rotating electric machine described above, the pressing body may be a winding wound around the bridge. In this case, since the pressing body is a winding wound around the bridge, it is easy to press the bridge in the axial direction.

[0009] In the rotor for the rotating electric machine described above, the pressing body may be wound around the bridge a plurality of times. In this case, since the winding, which is the clamping body, is wound around the bridge multiple times, when the rotor is rotating at a low speed, the axial stress in the bridge increases, suppressing leakage flux and enabling the rotor to obtain a higher torque.

[0010] Furthermore, in the rotor of the above-mentioned rotating electric machine, the bridge may comprise an outer bridge formed radially outside the rotor core and an inner bridge formed radially inside the rotor core, and the clamping body may be configured to clamp at least the outer bridge of the outer bridge and the inner bridge. In this case, the clamping body clamps at least the outer bridge of the outer bridge and the inner bridge, thereby making it possible to suppress the induced voltage when the rotor is rotating at high speeds, and at the same time, when the rotor is rotating at low speeds, leakage magnetic flux is suppressed, thereby enabling the rotor to obtain high torque. Effect of the Invention

[0011] According to the present invention, it is possible to provide a rotor for a rotating electric machine that is capable of suppressing induced voltage during rotation without increasing manufacturing costs or decreasing strength. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a rotating electric machine according to a first embodiment. [Diagram 2] 1 is a perspective view of a rotor of a rotating electric machine according to a first embodiment. [Diagram 3] 1 is a plan view of a main portion of a rotor of a rotating electric machine according to a first embodiment. [Figure 4] 4(a) is a cross-sectional view taken along line AA in FIG. 3, showing the rotor core and windings at high rotation speed, and FIG. 4(b) is a cross-sectional view taken along line AA in FIG. 3, showing the rotor core and windings at low rotation speed. [Diagram 5] FIG. 11 is a perspective view of a rotor of a rotating electric machine according to a second embodiment. [Figure 6] 1A is a cross-sectional view of the rotor core and windings at high rotation speed as viewed from the outer periphery of the rotor, and FIG. 1B is a cross-sectional view of the rotor core and windings at low rotation speed as viewed from the outer periphery of the rotor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (First embodiment) Hereinafter, a rotor of a rotating electric machine according to a first embodiment will be described with reference to the drawings. The rotating electric machine of this embodiment is a permanent magnet embedded synchronous motor, and is mounted on a vehicle. The rotating electric machine and the rotor of the rotating electric machine shown in the drawings are both schematic diagrams, and the shapes are exaggerated.

[0014] As shown in FIG. 1, a permanent magnet type rotating electric machine (hereinafter simply referred to as a "rotating electric machine") 10 includes a stator 11 and a rotor 12. The stator 11 has a cylindrical stator core 13. A plurality of slots 14 are formed on the inner periphery of the stator core 13. Each slot 14 opens to the inner periphery of the stator core 13. Teeth 15 are formed between each slot 14. Coils 16 are wound around the teeth 15. The rotor 12 is provided such that a gap is formed between the rotor 12 and the inner periphery of the stator core 13.

[0015] The rotor 12 is disposed inside the stator 11. As shown in FIG. 2, the rotor 12 has a rotor core 18 formed by laminating a plurality of (e.g., several tens of) disk-shaped electromagnetic steel plates 17. A shaft hole 19 is formed penetrating the center of the rotor core 18. A rotating shaft 20 is inserted into the shaft hole 19, and the rotating shaft 20 is fixed to the rotor core 18. The rotor core 18 can rotate integrally with the rotating shaft 20. The rotating shaft 20 is rotatably supported by a motor housing (not shown) via a bearing (not shown). For ease of explanation, the rotating shaft 20 is not shown in FIG. 2.

[0016] As shown in Fig. 3, rotor core 18 is formed with a plurality of pairs of magnet insertion holes 21 adjacent to each other in the circumferential direction of rotor core 18. The magnet insertion holes 21 are formed for each magnetic pole of rotor core 18 and pass through rotor core 18 along the penetrating direction of shaft hole 19. A pair of permanent magnets 22 of the same polarity are inserted into each pair of magnet insertion holes 21. The multiple pairs of permanent magnets 22 are embedded in rotor core 18 such that each pair has alternate magnetic polarities in the circumferential direction of rotor core 18.

[0017] Specifically, the stator 11 side is equipped with an N-pole permanent magnet (hereinafter referred to as "N-pole magnet") 22, and the stator 11 side is equipped with an S-pole permanent magnet (hereinafter referred to as "S-pole magnet") 22, and a first set of two S-pole magnets 22 arranged adjacent to each other and a second set of two N-pole magnets 22 arranged adjacent to each other are fixed to the rotor core 18 so as to be arranged alternately in the circumferential direction of the rotor core 18.

[0018] More specifically, rotor core 18 is circumferentially equally divided into a plurality of imaginary regions (six in this embodiment), and each of these imaginary regions has two magnet insertion holes 21 into which two S-pole magnets 22 making up a first set are inserted, and two magnet insertion holes 21 into which two N-pole magnets 22 making up a second set are inserted, which are alternately formed. Therefore, rotating electric machine 10 of this embodiment is a six-pole rotating electric machine. Note that when there is no distinction between N-pole magnets and S-pole magnets, the permanent magnets 22 will be referred to as permanent magnets 22.

[0019] As shown in Fig. 3, the magnet insertion hole 21 has a gap 23 formed by the permanent magnet 22 and the rotor core 18 and located on the outer periphery side of the rotor core 18, and a gap 24 formed by the permanent magnet 22 and the rotor core 18 and located on the inner periphery side of the rotor core 18. Each gap 23 acts as a flux barrier to effectively cause the magnetic flux to act on torque. Between adjacent gaps 23, an outer bridge 25 is formed as a bridge on the radial outside of the rotor core 18. An outer edge 26 is formed between the gap 23 and the outer periphery surface of the rotor core 18.

[0020] The air gaps 24 form non-magnetic regions in the magnet insertion holes 21. Between adjacent air gaps 24, inner bridges 27 are formed as bridges on the radially inner side of the rotor core 18.

[0021] The rotor core 18 has an outer circumferential core portion 28, which is between the pair of magnet insertion holes 21 and the outer circumferential surface of the rotor core 18 and is located on the outer circumferential side of the magnet insertion holes 21, and an inner circumferential core portion 29, which is located on the inner circumferential side of the magnet insertion holes 21 in the rotor core 18. The outer bridge 25 extends linearly from the inner circumferential core portion 29 toward the outer circumferential surface of the rotor core 18. The outer circumferential core portion 28 is supported by the inner bridge 27 and the outer edge portion 26. The inner bridge 27 extends linearly from the inner circumferential core portion 29 toward the outer circumferential surface of the rotor core 18. The pair of permanent magnets 22 are arranged in a V-shape with respect to the extending direction of the inner bridge 27. The outer circumferential core portion 28 and the inner circumferential core portion 29 correspond to a main magnetic flux region in which a main magnetic flux component generated by the permanent magnet 22 flows. The outer bridge 25 and the inner bridge 27 correspond to a leakage magnetic flux region in which leakage magnetic flux occurs.

[0022] In this embodiment, the metal winding 30 serving as a clamping body is inserted into adjacent gaps 23 and wound around the outer bridge 25 multiple times. Although not shown, both ends of the winding 30 are fixed to each other. The wound winding 30 is clamped against the outer bridge 25 in the axial direction of the rotating shaft 20. The winding 30 in this embodiment is made of an aluminum alloy, which is a non-magnetic material, and has a linear expansion coefficient larger than that of the electromagnetic steel sheet 17.

[0023] In this embodiment, the cross section of the winding 30 is circular, but there is no particular limitation on the shape of the cross section of the winding 30, and it may be, for example, rectangular. The number of turns of the winding 30 depends on the diameter of the winding 30, but is preferably about several turns. Winding the winding 30 about several times makes it easier to set the axial stress in the outer bridge 25 more appropriately. The diameter of the winding 30 may be any diameter that allows it to be inserted into the air gap 23.

[0024] Next, the operation of the rotating electric machine 10 of this embodiment will be described. When the rotating electric machine 10 is driven under a load, a current is supplied to the coil 16 of the rotor 12, generating a rotating magnetic field in the stator 11, and the rotating magnetic field acts on the rotor 12. Then, the rotor 12 rotates in synchronization with the rotating magnetic field due to the magnetic attraction and repulsion between the rotating magnetic field and the permanent magnets 22.

[0025] As the rotation speed of rotor 12 increases and rotor 12 rotates at a higher speed, the centrifugal force acting on rotor 12 increases. Rotor core 18 generates heat due to increased iron loss. As shown in FIG. 4(a), rotor 12 and windings 30 expand due to the heat generated by rotor 12. Because the linear expansion coefficient of windings 30 is greater than the linear expansion coefficient of electromagnetic steel sheets 17 constituting rotor core 18, the elongation of windings 30 in the axial direction of rotating shaft 20 becomes greater than the axial expansion of outer bridges 25. As a result, the clamping pressure applied by windings 30 to outer bridges 25 is alleviated, and rotor core 18 expands in the axial direction in response to the heat generation.

[0026] The axial expansion of rotor core 18 increases leakage flux through gap 23, and reduces the main magnetic flux. As a result, the induced voltage during high speed rotation of rotor 12 is suppressed, and the torque of rotating electric machine 10 is reduced.

[0027] On the other hand, when rotor 12 is rotating at low speeds, the centrifugal force is smaller than when rotor 12 is rotating at high speeds, and almost no heat is generated due to iron loss in rotor 12. For this reason, as shown in Fig. 4(b), rotor core 18 hardly expands in the axial direction, and the clamping pressure applied to outer bridge 25 by windings 30 is almost maintained. For this reason, axial stress is maintained in rotor core 18 by windings 30, and an increase in leakage flux through gaps 23 is suppressed, so the torque of rotating electric machine 10 increases.

[0028] The rotor 12 of the rotating electrical machine 10 according to this embodiment provides the following advantages. (1) A non-magnetic pressing body is inserted into the gap 23 formed by the permanent magnet 22 and the rotor core 18, and presses the outer bridge 25 of the rotor core 18 in the axial direction of the rotating shaft 20. Since the pressing body is non-magnetic, no leakage of magnetic flux occurs from the pressing body. When the rotation of the rotor 12 increases, the rotor core 18 generates heat due to an increase in iron loss. However, since the pressing body has a larger linear expansion coefficient than the electromagnetic steel sheet 17 constituting the rotor core 18, the amount of axial expansion of the pressing body due to heat generation is larger than that of the rotor core 18. Therefore, the axial stress of the outer bridge 25 of the rotor core 18 caused by the pressing body is reduced. When the axial stress of the outer bridge 25 caused by the pressing body is reduced, the leakage magnetic flux increases, and the induced voltage during high rotation can be suppressed. At low rotation speeds of the rotor 12, the centrifugal force is smaller than at high rotation speeds, so the rotor core 18 hardly expands in the axial direction, and the axial stress of the rotor core 18 due to the pressing body is maintained, so leakage flux in the rotor core 18 is suppressed, and high torque can be obtained from the rotor 12. In this way, the rotor 12 is a variable field magnet rotor, and it is possible to make the field magnet different at high rotation speeds from the field magnet at low rotation speeds. Furthermore, by using the pressing body, there is no need to use expensive magnetic property variable elements, which not only reduces the manufacturing costs of the rotor 12 but also prevents a decrease in the strength of the rotor core 18.

[0029] (2) Since the pressing body is the winding 30 wound around the outer bridge 25, it is easy to press the outer bridge 25 of the rotor core 18 in the axial direction. In addition, since the pressing body is the winding 30, it is easy to insert the pressing body into the gap 23.

[0030] (3) Since the winding 30, which is a clamping body, is wound multiple times around the outer bridge 25, the axial stress in the outer bridge 25 of the rotor core 18 increases when the rotor 12 is rotating at a low speed, suppressing leakage flux and enabling the rotor 12 to obtain a higher torque. Note that the diameter of the winding 30 may be increased so that the outer bridge 25 is clamped in the axial direction of the rotating shaft 20 with one turn.

[0031] (4) The winding 30 is made of an aluminum-based alloy, and therefore it is easy to realize a sandwiched body that is non-magnetic and has a linear expansion coefficient larger than that of the electromagnetic steel sheets 17 .

[0032] Second embodiment Next, a rotor for a permanent magnet type rotating electric machine according to a second embodiment will be described. The rotor according to this embodiment differs from the first embodiment in the configuration of the pressing body. In this embodiment, the same configuration as in the first embodiment will be referred to and the same reference numerals will be used.

[0033] In a rotor 41 of a rotating electric machine 40 shown in Fig. 5, a metal body 42 is inserted as a clamping body into a gap 23 formed in a rotor core 18, and the metal body 42 clamps the outer bridge 25. The metal body 42 has an insertion portion 43 inserted into the gap 23 and a pressing portion 44 extending from both ends of the insertion portion 43 in a direction perpendicular to the insertion direction. The metal body 42 is made of an aluminum-based alloy, which is a non-magnetic material. Therefore, the linear expansion coefficient of the metal body 42 is larger than that of the electromagnetic steel sheet 17.

[0034] The insertion portion 43 is a rectangular columnar rod body, and is set to have a cross-sectional area that allows it to be inserted into the gap 23. The pressing portion 44 is a portion that comes into contact with the outer bridge 25 and generates axial stress in the outer bridge 25. In other words, the metal body 42 generates axial stress in the outer bridge 25 without being wound around the outer bridge 25.

[0035] In this embodiment, as the rotation speed of the rotor 41 increases and the rotor 12 rotates at a higher speed, the rotor 41 generates heat due to an increase in iron loss. As shown in Fig. 6(a), the rotor 41 and the metal body 42 expand due to the heat generated by the rotor 41. Because the linear expansion coefficient of the metal body 42 is greater than the linear expansion coefficient of the electromagnetic steel sheets 17 constituting the rotor core 18, the elongation of the metal body 42 in the axial direction is greater than the axial expansion of the outer bridges 25. As a result, the clamping pressure applied to the outer bridges 25 by the metal body 42 is alleviated, and the rotor core 18 expands in the axial direction in response to the heat generation.

[0036] On the other hand, when rotor 41 is rotating at low speeds, there is almost no heat generation in rotor 41 due to iron loss compared to when rotor 41 is rotating at high speeds. Therefore, as shown in Fig. 6(b), rotor core 18 hardly expands in the axial direction, and the clamping pressure applied to outer bridge 25 by metal body 42 is almost maintained. Therefore, axial stress is maintained in rotor core 18 by metal body 42, and an increase in leakage flux through gap 23 is suppressed, so the torque of rotating electric machine 40 increases.

[0037] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit of the invention. For example, the following modifications may be made.

[0038] In the above embodiment, the pressing body is made of an aluminum alloy, but is not limited to this. The pressing body may be made of, for example, a zinc-based alloy, and may be made of any non-magnetic material that has a linear expansion coefficient greater than that of an electromagnetic steel sheet and can be pressed against the bridge in the axial direction, and is not limited to a metal material. In the above embodiment, the outer bridge clamping body that clamps the outer bridge of the rotor core has been described as an example, but the present invention is not limited to this. The clamping body is not limited to the outer bridge clamping body that clamps the outer bridge, but may be, for example, an inner bridge clamping body that clamps the inner bridge. Alternatively, only the inner bridge clamping body that clamps the inner bridge may be provided. In the above embodiment, the pressing body is inserted into the gap serving as the flux barrier, and a gap is left between the pressing body and the rotor core in the gap. However, the present invention is not limited to this. For example, the pressing body may be inserted into the gap so as to fill the gap. In the above embodiment, the rotor is provided with 12 permanent magnets, but this is not limited to this number. The number of permanent magnets may be, for example, 4, 8, or 16, and is not particularly limited. Furthermore, the arrangement of the permanent magnets is not limited to a V-shape. [Explanation of symbols]

[0039] 10, 40 Permanent magnet type rotating electric machine 11 Stator 12, 41 Rotor 13 Stator core 14 Slots 15 Teeth 16 Coils 17 Electrical steel sheet 18 Rotor core 19 Shaft hole 20 Rotational Axis 21 Magnet insertion hole 22 Permanent magnets 23 void (outside) 24 Void (inside) 25 Outer Bridge 26 Outer edge 27 Inner Bridge 28 Core Outer Part 29 Inner circumference of core 30 Winding (clamped body) 42 Metal body (clamped body) 43 Insertion section 44 Holding part

Claims

1. a rotor core formed by laminating electromagnetic steel sheets; A rotating shaft that is inserted through the center of the rotor core and integrated with the rotor core; a magnet insertion hole formed for each magnetic pole of the rotor core and extending along the axial direction of the rotating shaft; A permanent magnet is inserted into the magnet insertion hole; A rotor for a rotating electric machine having a gap formed by the permanent magnet and the rotor core in the magnet insertion hole, The rotor core is provided with a plurality of pairs of the magnet insertion holes adjacent to each other in a circumferential direction of the rotor core, A bridge is formed between adjacent gaps, a clamping body that is inserted into the gap and clamps the bridge in an axial direction of the rotation shaft, 4. A rotor for a rotating electric machine, wherein the pressing body is made of a non-magnetic material having a linear expansion coefficient greater than that of the electromagnetic steel sheets.

2. 2. The rotor for a rotating electric machine according to claim 1, wherein the pressing body is a winding wound around the bridge.

3. 3. The rotor for a rotating electric machine according to claim 2, wherein the pressing body is wound around the bridge a plurality of times.

4. The bridge is an outer bridge formed on the radially outer side of the rotor core; an inner bridge formed on the radially inner side of the rotor core, 4. The rotor for a rotating electric machine according to claim 1, wherein the pressing body presses at least the outer bridge out of the outer bridge and the inner bridge.

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