Rotary electric machine and electric vehicle provided with same

Abstract

The purpose of the present invention is to inhibit vibration due to an electromagnetic exciting force of a magnetic wedge to thereby ensure long-term reliability of a rotary electric machine.　A rotary electric machine 100 according to the present invention comprises: a stator 3; and a rotor 2 disposed in the stator 3 with a gap therebetween. The stator 3 comprises: a stator iron core 9 having a stator slot 11; and stator coils 13 inserted into the stator iron core 9. The stator also comprises a magnetic wedge 10 for holding the stator coils 13 at a slot opening part 11a of the stator slot 11.　Both edge portions of the magnetic wedge 10 are inserted into groove parts 9a provided in the stator iron core 9. The portions of the magnetic wedge 10 which are inserted into the groove parts 9a are defined as insertion portions 10a of the magnetic wedge 10. The positions of contact between the groove parts 9a and the insertion portions 10a of the magnetic wedge 10 are located between the circumferential centers of the insertion portions 10a of the magnetic wedge 10 and the circumferential center of the magnetic wedge 10. A buffer material 20 having a width wider than the distance between the contact positions of the groove parts 9a and the insertion portions 10a of the magnetic wedge 10 is provided between the magnetic wedge 10 and a stator coil 13.

Description

Rotating electric machine and electric vehicle equipped with the same

[0001] The present invention relates to a rotating electric machine and an electric vehicle equipped with the same.

[0002] In recent years, increasing the efficiency of rotating electrical machines is required to save energy and reduce carbon dioxide emissions as electrification advances. Higher efficiency is particularly important for induction motors, which are already widely used in industrial applications and for mobility, including railways. Induction motors have conductor bars in their rotors. It is known that these conductor bars generate a loss called high-frequency secondary copper loss due to permeance changes in the slots, resulting in reduced efficiency. The use of magnetic wedges has been proposed as an item for reducing this high-frequency secondary copper loss.

[0003] A wedge is a component placed at the slot opening after the stator coil of an induction motor is inserted to prevent the stator coil from detaching from the slot. While non-magnetic materials are typically used for wedges, magnetic wedges are wedges that have been made magnetic. Because high efficiency can be easily achieved simply by replacing conventional non-magnetic wedges with magnetic wedges, magnetic wedges have recently come to be seen as an important item for increasing the efficiency of not only induction motors but also a wide range of rotating electrical machines.

[0004] However, since the magnetic wedge itself is magnetic and is subjected to electromagnetic excitation force, there is a risk of noise increase due to vibration of the magnetic wedge and malfunction of the rotating electric machine due to the magnetic wedge cracking. Therefore, the technology for fixing the magnetic wedge is important for obtaining a highly efficient rotating electric machine.

[0005] An example of a prior art document related to the above-mentioned magnetic wedge fixing technology is Patent Document 1, entitled "Magnetic Wedge for Rotating Electric Machine." Paragraph

[0009] of Patent Document 1 states, "A magnetic wedge 5 is inserted into the opening 2a of the slot 2 to support and fix the winding 4. The magnetic wedge 5 is fixed in a groove provided in the side wall of the core teeth 1a, 1b, which holds the magnetic wedge 5 itself and supports and fixes the winding 4." In Patent Document 1, grooves are provided in the side wall of the core teeth 1a, 1b of the slot 2 of the stator core 1, and the magnetic wedge 5 is inserted into the groove and fixed.

[0006] Japanese Patent Application Publication No. 5-22885

[0007] Typically, rotating electric machines have a thickness in the axial direction, which causes three-dimensional dimensional variations. In the magnetic wedge fixing technology described in the aforementioned Patent Document 1, the three-dimensional dimensional variations cause areas where the magnetic wedge and the groove of the stator core cannot make contact, making these areas weak and making the magnetic wedge more susceptible to vibration due to electromagnetic excitation forces. In particular, because the dimensional tolerance of a typical magnetic wedge is larger than that of the stator core, the contact area between the magnetic wedge and the groove of the stator core cannot be designed using conventional technology. Therefore, even if the magnetic wedge and the groove of the stator core appear to be in surface contact on a drawing, there is a possibility that they actually make point contact at an unexpected location.

[0008] Furthermore, it is known that actual rotating electric machines repeatedly experience temperature changes, such as high and low temperatures, due to starting and stopping, load changes, and the like. At high temperatures, the magnetic wedge is subjected to radial pressure toward the rotor due to thermal expansion of the stator coil. In this case, if the contact point between the magnetic wedge and the groove in the stator core is the end of the magnetic wedge in the circumferential direction of the stator, a large bending moment is applied to the end of the magnetic wedge. Repeated application of a large bending moment to the magnetic wedge increases the risk of damage to the magnetic wedge. A damaged magnetic wedge may become trapped in the gap between the stator and rotor, which could result in malfunction or destruction of the rotating electric machine.

[0009] The magnetic wedge fixing technology described in the above-mentioned Patent Document 1 does not take into consideration the effects of the above-mentioned temperature changes, such as the magnetic wedge becoming tightly fixed or, conversely, loosening, or the bending moment acting on the magnetic wedge, and is therefore insufficient in terms of long-term reliability.

[0010] The present invention has been made in consideration of the above points, and its object is to provide a rotating electric machine and an electric vehicle equipped with the same that can suppress vibrations caused by electromagnetic excitation forces of the magnetic wedge, support and fix the magnetic wedge even when temperature changes occur due to starting, stopping, or changes in load, etc., thereby ensuring long-term reliability.

[0011] In order to achieve the above object, the rotating electric machine of the present invention comprises a stator and a rotor arranged on the stator via a gap, the stator comprising a stator core having stator slots and a stator coil inserted into the stator core, and a magnetic wedge that holds the stator coil at the slot opening of the stator slot, wherein both ends of the magnetic wedge are inserted into grooves provided in the stator core, the portion of the magnetic wedge inserted into the groove is the insertion portion of the magnetic wedge, the contact position between the groove and the insertion portion of the magnetic wedge is located between the circumferential center of the insertion portion of the magnetic wedge and the circumferential center of the magnetic wedge, and a buffer material wider than the contact position between the groove and the insertion portion of the magnetic wedge is provided between the magnetic wedge and the stator coil.

[0012] According to the present invention, it is possible to suppress vibrations caused by electromagnetic excitation forces of the magnetic wedge, and to support and fix the magnetic wedge even when temperature changes occur due to starting, stopping, or load changes, etc., thereby providing a rotating electric machine and an electric vehicle equipped with the same that ensure long-term reliability.

[0013] FIG. 1 is a cross-sectional view showing half of the overall configuration of a rotating electric machine 100 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II' in FIG. 1. FIG. 3 is a partially enlarged cross-sectional view of the stator slot 11 in FIG. 2. FIG. 4 is a partially enlarged cross-sectional view of the stator slot 11 according to a second embodiment of the present invention. FIG. 5 is a partially enlarged cross-sectional view of the stator slot 11 according to a third embodiment of the present invention. FIG. 6 is a partially enlarged cross-sectional view of the stator slot 11 according to a fourth embodiment of the present invention. FIG. 7 is a partially enlarged cross-sectional view of the stator slot 11 according to a fifth embodiment of the present invention. FIG. 8 is a diagram showing a schematic configuration of an electric vehicle according to an eighth embodiment of the present invention.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In principle, identical elements are designated by the same reference numerals in all drawings. Furthermore, descriptions of parts having identical functions will be omitted. Note that the configurations described below are merely examples, and it is not intended that the embodiments of the present invention be limited to the specific embodiments below.

[0015] In the following explanation, an example using an induction motor is shown, but the present invention is not limited to this. The present invention is not limited to induction machines and may be applied to synchronous machines such as synchronous machines with permanent magnets in the rotor or synchronous machines with salient poles in the rotor core.

[0016] Fig. 1 is a cross-sectional view showing half of the overall configuration of a rotating electrical machine 100 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II' in Fig. 1. Note that a frame 1 is omitted in Fig. 2.

[0017] As shown in Fig. 1, in a rotating electric machine 100 of this embodiment, a rotor 2 and a stator 3 are arranged within a frame 1, facing the rotor 2 across a predetermined radial gap 14. Bearings 4a and 4b that support the rotation of the rotor 2 are installed on the frame 1. The rotor 2 is fastened to a shaft 5, and is provided with conductor bars 12 that are arranged in slots of a rotor core 7. The conductor bars 12 protrude in the axial direction from both axial ends of the rotor core 7, and end rings 8 are connected to both protruding axial ends.

[0018] On the other hand, the stator 3 is fixed to the frame 1, and is provided with stator coils 13 inserted into stator slots 11 of the stator core 9. The stator coils 13 have stator coil ends 13a that protrude axially from both axial ends of the stator core 9. Wedges that hold the stator coils 13 are provided at the openings of the stator slots 11. In this embodiment, the wedges are magnetic wedges 10 that are magnetic. The magnetic wedges 10 are made of, for example, spherical magnetic metal particles.

[0019] 1 and 2, the main components constituting the rotor 2 and stator 3 are roughly composed of a rotor core 7, a stator core 9, conductor bars 12, a stator coil 13, gaps 14, and magnetic wedges 10 made of an iron-based magnetic material that prevent the stator coil 13 from protruding. The rotor 2 may also be provided with an axial duct 18 on the inner diameter side of the rotor core 7 for axially flowing a refrigerant. Furthermore, a frame 1 fixed to the stator 3 is disposed on the outer diameter side of the stator 3, and the fixed portions of the stator 3 and the frame 1 are fixed at a predetermined interval in the circumferential direction, and a ventilation duct 19 for axially flowing a refrigerant may be provided between the fixed portions. Reference numeral 6 denotes stator teeth.

[0020] Furthermore, the rotor 2 shown in FIGS. 1 and 2 is a rotor of a so-called induction motor, but the effects of the present invention can be obtained not only with induction machines but also with synchronous machines, such as synchronous machines whose rotors have permanent magnets or synchronous machines whose cores have salient poles.

[0021] In the following description, the "radial direction DR" is a linear direction that intersects perpendicularly with the rotation axis C and is a radial direction centered on the rotation axis C. The "circumferential direction Dθ" is a circumferential direction centered on the rotation axis C and is the direction of rotation around the rotation axis C. The "axial direction DZ" is a linear direction parallel to the rotation axis C and is a direction along the rotation axis C. In addition, the side closer to the rotation axis C is defined as the "radially inner side" and the side farther away from the rotation axis C is defined as the "radially outer side." Furthermore, the direction moving away from the circumferential center of the slot opening 11a or the circumferential center position of the magnetic wedge 10 in the circumferential direction is defined as the "circumferential outer side."

[0022] Next, the magnetic wedge 10 in the rotating electrical machine 100 of this embodiment will be specifically described with reference to Fig. 3. Fig. 3 is a partially enlarged cross-sectional view of the stator slot 11 in Fig. 2.

[0023] As shown in Fig. 3, the stator core 9 has stator slots 11 that house stator coils 13. A slot opening 11a is formed on the gap 14 side (upper side in Fig. 3) of the stator slot 11. A magnetic wedge 10 that holds the stator coil 13 is disposed in the slot opening 11a.

[0024] In this embodiment, both ends of the magnetic wedge 10 are inserted into grooves 9a formed on both side surfaces of the slot opening 11a of the stator core 9. The circumferential width of the grooves 9a is wider than the circumferential width of the slot opening 11a and the stator slot 11.

[0025] If the portion of the magnetic wedge 10 inserted into the groove 9a is the insertion portion 10a of the magnetic wedge, the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 is located between the circumferential center (left-right direction in FIG. 3 ) of the insertion portion 10a of the magnetic wedge 10 and the circumferential center of the magnetic wedge 10. In other words, the contact position between the insertion portion 10a of the magnetic wedge 10 and the groove 9a is not a position close to the circumferential end 10a1 of the magnetic wedge 10, but a position close to the circumferential center of the magnetic wedge 10.

[0026] In this groove 9a, a clearance 15 having a radial width of approximately 0.1 to 2.0 mm is provided between the magnetic wedge 10 and the stator core 9 on the anti-gap side (lower side in FIG. 3 ) facing the circumferential end 10a1 of the magnetic wedge 10, and a buffer material 20 that is wider in the circumferential direction than the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 is provided in this clearance 15. In this embodiment, the magnetic wedge 10 is fixed and supported by the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 and the contact surface with the buffer material 20 provided in the clearance 15. In other words, the magnetic wedge 10 is fixed and supported to the stator 3 by the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 and the contact surface with the buffer material 20 inserted between the magnetic wedge 10 and the stator coil 13.

[0027] The buffer material 20 is made of, for example, heat-resistant and electrically insulating glass fiber paper, glass fiber nonwoven fabric, or a sheet made of polyacetal resin.

[0028] Furthermore, the clearance 15 may be filled with varnish 16. The varnish 16 may simply be filled in the clearance 15, or, because the clearance 15 and the stator slot 11 into which the stator coil 13 is inserted are in communication with each other, the varnish 16 may be filled not only in the clearance 15 but also in the stator slot 11 into which the stator coil 13 is inserted. By providing the clearance 15 described above, the magnetic wedge 10 and the varnish 16 are bonded not only to the opposing surfaces of the magnetic wedge 10 and the stator coil 13, but also to the opposing surfaces of the magnetic wedge insertion portion 10a and the groove portion 9a.

[0029] (Effect on Electromagnetic Vibration) The magnetic wedge 10 is magnetic and is therefore subjected to electromagnetic excitation force. In conventional structures, the magnetic wedge 10 is fixed and supported to the stator 3 by the contact position between the groove 9 a and the insertion portion 10 a of the magnetic wedge 10 and the contact surface with the stator coil 13 on the opposite side of the gap. However, the dimensional tolerance of the magnetic wedge 10 is generally large, at ±0.1 mm, and even with precise design, there is a risk that the contact position between the groove 9 a and the insertion portion 10 a of the magnetic wedge 10 will be at the circumferential end 10 a 1 of the magnetic wedge 10. In this case, the magnetic wedge 10 will be subjected to the electromagnetic excitation force at the circumferential end 10 a 1 of the magnetic wedge 10, and a large bending moment will be generated in the magnetic wedge 10.

[0030] This increases the bending stress generated in the magnetic wedge 10. Repeated application of large bending stresses accumulates fatigue in the magnetic wedge 10, potentially causing the magnetic wedge 10 to wear, deform, or crack. In particular, because a typical magnetic wedge 10 has a shape in which its radial width narrows toward its circumferential end 10a1, the bending stress generated in the magnetic wedge 10 could potentially damage the circumferential end 10a1 of the magnetic wedge. Therefore, with the conventional structure, there is a risk of increased noise due to the magnetic wedge 10 vibrating due to electromagnetic excitation force, or of the magnetic wedge cracking, causing a malfunction of the rotating electric machine.

[0031] On the other hand, in the structure of this embodiment, the magnetic wedge 10 is fixed and supported to the stator 3 by the contact position between the groove 9 a and the magnetic wedge insertion portion 10 a and the contact surface with the buffer material 20 on the anti-gap side, but the contact position between the groove 9 a and the magnetic wedge insertion portion 10 a is located between the circumferential center of the magnetic wedge insertion portion 10 a and the circumferential center of the magnetic wedge 10. In this case, the magnetic wedge 10 receives the load between the circumferential center of the magnetic wedge insertion portion 10 a and the circumferential center of the magnetic wedge 10, i.e., at a position closer to the circumferential center of the magnetic wedge 10 than the circumferential end portion 10 a 1 of the magnetic wedge 10, thereby reducing or almost eliminating the bending moment generated in the magnetic wedge 10. This reduces the bending stress generated in the magnetic wedge 10, thereby reducing fatigue accumulated when bending stress is repeatedly generated and reducing the risk of the magnetic wedge 10 cracking. According to this embodiment, by using the above structure, noise caused by the magnetic wedge 10 vibrating due to electromagnetic excitation force can be reduced, and the risk of malfunction of the rotating electric machine due to the magnetic wedge 10 cracking can be suppressed.

[0032] (Effect on thermal expansion) Generally, the linear expansion coefficients of the stator core 9 and the stator coil 13 are different, so stress is generated in the magnetic wedge 10 due to the difference in thermal expansion and contraction between the stator core 9 and the stator coil 13 (the difference in the amount of expansion and contraction displacement of the components due to heating and cooling).

[0033] In the conventional structure, the magnetic wedge 10 is fixed and supported to the stator 3 by the contact position between the groove 9 a and the insertion portion 10 a of the magnetic wedge 10 and the contact surface with the stator coil 13 on the opposite side of the gap. However, the dimensional tolerance of the magnetic wedge 10 is generally large, at ±0.1 mm. Even with precise design, there is a risk that the contact position between the groove 9 a and the insertion portion 10 a of the magnetic wedge 10 will be at the circumferential end 10 a 1 of the magnetic wedge 10. In this case, the surface pressure due to thermal expansion of the stator coil 13 occurs mainly at the circumferential center of the magnetic wedge 10, and the magnetic wedge 10 bears this load at the circumferential end 10 a 1 of the magnetic wedge 10, resulting in a large bending moment in the magnetic wedge 10. This increases the bending stress in the magnetic wedge 10. Repeated large bending stresses accumulate fatigue in the magnetic wedge 10, potentially causing the magnetic wedge 10 to crack. In particular, since a typical magnetic wedge 10 has a shape in which its radial width narrows toward its circumferential end 10a1, there is a possibility that the bending stress generated in the magnetic wedge 10 may cause the circumferential end 10a1 of the magnetic wedge 10 to break.

[0034] On the other hand, in the structure of this embodiment, the magnetic wedge 10 is fixed and supported to the stator 3 by the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 and the contact surface with the buffer material 20 on the opposite side of the gap, but (A) the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10 is located between the circumferential center of the insertion portion 10a of the magnetic wedge 10 and the circumferential center of the magnetic wedge 10, and (B) the buffer material 20 is wider in the circumferential direction than the contact position between the groove 9a and the insertion portion 10a of the magnetic wedge 10. The above (A) and (B) are features of this embodiment. In this case, the surface pressure due to thermal expansion of the stator coil 13 is widely dispersed in the circumferential direction of the magnetic wedge 10 by the buffer material 20. Furthermore, because the magnetic wedge 10 receives the load between the circumferential center of the insertion portion 10a of the magnetic wedge 10 and the circumferential center of the magnetic wedge 10 itself, i.e., at a position closer to the circumferential center of the magnetic wedge 10 than the circumferential end portion 10a1 of the magnetic wedge 10, the bending moment generated in the magnetic wedge 10 can be reduced or made almost zero. This reduces the bending stress generated in the magnetic wedge 10, thereby reducing fatigue that accumulates when repeated bending stress is generated and lowering the risk of the magnetic wedge 10 cracking. According to this embodiment, by using the above structure, the magnetic wedge 10 can be reliably fixed and supported even when the temperature changes, and long-term reliability can be achieved.

[0035] Furthermore, when the clearance 15 is filled with varnish 16, the only surrounding material at the insertion portion 10a of the magnetic wedge 10 in the groove portion 9a is the stator core 9, so there is almost no change in the width of the clearance 15 due to thermal contraction of the material, and the varnish 16 on the opposing surface between the magnetic wedge 10 and the groove portion 9a does not peel off even if there is a temperature change in the rotating electric motor 100, allowing the magnetic wedge 10 to be fixed and supported to the stator 3.

[0036] Next, the holding state of the magnetic wedges 10 during assembly of the stator 3 and operation in the structure of this embodiment described above will be described.

[0037] In the assembly process of the stator 3, first, the stator coils 13 are inserted into the stator slots 11 of the stator core 9, and then the buffer materials 20 and magnetic wedges 10 are inserted axially. Then, the stator 3 is heated, and varnish 16 is injected into the stator slots 11 at a high temperature and cured at a high temperature.

[0038] At this time, the stator 3 is in a high temperature state, and therefore each component constituting the stator 3 is thermally expanding. In particular, when comparing the linear expansion coefficients of the stator core 9 (mainly iron) and the stator coil 13 (mainly copper), the stator coil 13 has a larger coefficient of linear expansion. Therefore, due to the thermal expansion of the stator coil 13, the magnetic wedge 10 is subjected to surface pressure in the direction of the gap 14.

[0039] For the same reasons as described above, in the conventional structure, a large bending moment is generated in the magnetic wedge 10. This increases the bending stress generated in the magnetic wedge 10, which may cause the magnetic wedge 10 to crack during assembly. In particular, because a typical magnetic wedge 10 has a shape in which the radial width narrows toward its circumferential end 10a1, the bending stress generated in the magnetic wedge 10 may cause the circumferential end 10a1 of the magnetic wedge to break during assembly.

[0040] On the other hand, in the structure of this embodiment, the bending moment generated in the magnetic wedge 10 is small or almost zero, so the bending stress generated in the magnetic wedge 10 is small, reducing the risk of the magnetic wedge 10 cracking during assembly.

[0041] Furthermore, when the varnish 16 is injected, the magnetic wedge 10 and the stator coil 13 become hot and are in close contact with each other, so that almost no varnish 16 is filled between the magnetic wedge 10 and the buffer material 20, or between the buffer material 20 and the stator coil 13.

[0042] However, in the groove 9a into which the magnetic wedge 10 is inserted, a clearance 15 is provided between the magnetic wedge 10 and the stator core 9 on the anti-gap side (lower side in Figure 3) facing the circumferential end (left-right direction in Figure 3) of the magnetic wedge 10, so the injected varnish 16 fills not only the circumferential side surface of the stator coil 13 but also the clearance 15 in the groove 9a and hardens.

[0043] When the stator 3 is cooled after the varnish 16 hardening conditions are met, the stator core 9 and stator coil 13, which have been thermally expanded, contract. At this time, the expanded stator coil 13 attempts to contract radially. Because there is no or very little varnish 16 between the magnetic wedge 10 and the stator coil 13, which were in close contact when the varnish 16 was injected, the magnetic wedge 10 and the buffer material 20, or the buffer material 20 and the stator coil 13, easily peel off. On the other hand, the radial depth of the clearance 15 of the groove 9a is short (narrow) compared to the radial depth of the stator slot 11, and therefore is less susceptible to the effects of thermal contraction.

[0044] Therefore, the varnish 16 filled in the clearance 15 adheres to the magnetic wedge 10 without peeling off, and the magnetic wedge 10 is fixed and supported on the stator core 9 .

[0045] Since the varnish 16 is injected in liquid form and then hardened (solidified), it has a thickness in the axial direction of the rotating electric machine 100, and even if there is variation in three-dimensional dimensions, the varnish 16 can be reliably filled into the clearance 15 between the magnetic wedge 10 and the groove 9a of the stator core 9, so the magnetic wedge 10 is reliably fixed and supported in the clearance 15 and will not vibrate even when subjected to electromagnetic excitation force.

[0046] As described above, in the configuration of this embodiment, by fixing and supporting the magnetic wedge 10 to the stator 3 at an appropriate contact position, the magnetic wedge 10 does not vibrate even when subjected to electromagnetic excitation force or temperature changes. This makes it less likely that an increase in noise due to vibration of the magnetic wedge 10 or failure of the rotating electric machine 100 due to cracking of the magnetic wedge 10 will occur. Furthermore, because the magnetic wedge 10 can be reliably fixed and supported without problems even when the surrounding material undergoes thermal contraction due to temperature changes, it is possible to provide a rotating electric machine 100 equipped with a stator 3 that has high long-term reliability.

[0047] Furthermore, since it becomes possible to provide a rotating electric machine 100 that employs magnetic wedges 10 with long-term reliability, it is possible to reduce high-frequency loss due to high-frequency magnetic flux generated on the surface of gap 14 between stator 3 and rotor 2 of rotating electric machine 100, thereby making rotating electric machine 100 highly efficient. In particular, when rotating electric machine 100 is an induction motor, it is possible to reduce high-frequency secondary copper loss, making it possible to achieve high efficiency of the induction motor at low cost.

[0048] Furthermore, in this embodiment, the magnetic wedge 10 has a shape that is convex toward the gap 14 (upper side in FIG. 3 ). By making the magnetic wedge 10 convex toward the gap 14, the magnetic wedge 10 protrudes radially (upper side in FIG. 3 ) toward the gap 14 beyond the groove 9 a. By bringing the tip of the magnetic wedge 10 closer to the gap 14, magnetic flux pulsation caused by high frequency waves that occurs on the gap 14 surface between the stator 3 and the rotor 2 is effectively alleviated. This reduces high-frequency loss, for example, high-frequency secondary copper loss that occurs in the conductor bars 12 of the rotor 2, and improves the efficiency of the rotating electric machine 100. This reduces the power consumption required to operate the rotating electric machine 100, contributing to a reduction in CO2 emissions.

[0049] Furthermore, by making the cross-sectional shape of the magnetic wedge 10 convex toward the gap 14 side, not only is pulsation of magnetic flux caused by high frequency generated on the surface of the gap 14 between the stator 3 and the rotor 2 effectively alleviated, but also, since there are no acute angles, including right angles, in the cross section of the groove 9 a on the gap 14 side and the cross section of the magnetic wedge 10, local concentration of stress generated in the stator teeth 6 and the magnetic wedge 10 is alleviated when the magnetic wedge 10 is subjected to pressure from the stator coil 13 at high temperatures. This not only reduces high-frequency secondary copper loss, but also alleviates local concentration of stress on the stator teeth 6 and the magnetic wedge 10, making it possible to prevent plastic deformation and cracking of the tips of the stator teeth 6 and the magnetic wedge 10, thereby improving the long-term reliability of the rotating electric machine 100.

[0050] With the configuration of this embodiment, the magnetic wedge 10 is held firmly to prevent vibration due to electromagnetic excitation force, and the magnetic wedge 10 can be reliably supported and fixed even when temperature changes occur due to starting, stopping, or load changes, etc., resulting in long-term reliability.

[0051] Next, a second embodiment will be described with reference to Fig. 4. Fig. 4 is a partially enlarged cross-sectional view of a stator slot 11 according to the second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0052] In this embodiment, the cross section of the magnetic wedge 10 is a trapezoidal shape that is convex toward the gap 14 (upper side in FIG. 4).

[0053] The groove 9a has a tapered portion 9a1 that is inclined toward the opposite side of the gap from the end position of the slot opening 11a toward the outside in the circumferential direction.

[0054] The magnetic wedge 10 has a tapered portion 10b that is inclined toward the anti-gap side as it moves from the circumferential center side to the circumferential outer side (end) of the magnetic wedge 10. When the taper angle of each of the tapered portions 9a1, 10b is defined as the opening angle from the circumferential axis, the angle of the tapered portion 9a1 of the groove portion 9a is set to be equal to or smaller than the angle of the tapered portion 10b of the magnetic wedge 10.

[0055] Due to the taper angle difference, the contact position between the tapered portion 9a1 of the groove 9a and the tapered portion 10b of the magnetic wedge 10 is located between the center of the tapered portion 10b (insertion portion 10a) of the magnetic wedge 10 and the center of the magnetic wedge 10. In addition, a buffer material 20 wider than the contact position between the tapered portion 9a1 of the groove and the tapered portion 10b of the magnetic wedge is provided between the magnetic wedge 10 and the stator coil 13.

[0056] In this embodiment, the contact position between the groove portion 9a and the magnetic wedge 10 can be determined by controlling the taper angle (taper portion 9a1, tapered portion 10b) of the groove portion 9a and the magnetic wedge 10, so that with a simple structure, the holding force of the magnetic wedge 10 can be increased and the long-term reliability of the rotating electric motor 100 can be improved.

[0057] Next, a third embodiment will be described with reference to Fig. 5. Fig. 5 is a partially enlarged cross-sectional view of a stator slot 11 according to the third embodiment of the present invention. The same components as those in the first and second embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0058] The groove 9a has a tapered portion 9a1 that is inclined toward the opposite side of the gap from the end position of the slot opening 11a toward the outside in the circumferential direction.

[0059] The magnetic wedge 10 has a tapered portion 10b that is inclined toward the anti-gap side from the circumferential center side of the magnetic wedge 10 toward the circumferential outer side (end) thereof.

[0060] As shown in Fig. 5, the grooves 9a in this embodiment are formed in a stepped pattern with different widths in the circumferential direction (left-right direction in Fig. 5), and include a first groove portion 9a2 (deepest portion) that is the widest circumferential width of the stepped grooves 9a and the deepest part, and a second groove portion 9a4 that is narrower circumferentially than the first groove portion 9a2. The insertion portion 10a of the magnetic wedge 10 is inserted into the first groove portion 9a2, and the stator core 9 and the magnetic wedge 10 are in contact at the first groove portion 9a2. A buffer material 20 is also arranged in the second groove portion 9a4.

[0061] By configuring this embodiment in this manner, it is possible to obtain the same effects as in embodiment 1, and since the magnetic wedge 10 is in contact with the stator core 9 in the first groove portion 9a2 of the stepped groove portion 9a, the magnetic wedge 10 is fixed and supported not only by contact between the groove portion 9a and the buffer material 20 but also by metal contact with the stator core 9.

[0062] In this structure, even if the magnetic wedge 10 heats up and expands due to an increase in the amount of harmonic magnetic flux, the thermal expansion of the magnetic wedge 10 can be suppressed by the metal-to-metal contact portion with the stator core 9, eliminating the risk of crushing the varnish 16 in the clearance 15 in the groove 9 a. This allows the magnetic wedge 10 to be stably held in the stator core 9, improving the long-term reliability of the rotating electric machine 100.

[0063] Next, a fourth embodiment will be described with reference to Fig. 6. Fig. 6 is a partially enlarged cross-sectional view of a stator slot 11 according to a fourth embodiment of the present invention. The same components as those in the first to third embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0064] The groove 9a includes a tapered portion 9a1 (first tapered portion) that slopes toward the opposite side from the gap as it extends circumferentially outward from the end of the slot opening 11a. The groove 9a also includes a tapered portion 9a3 (second tapered portion) that slopes toward the gap as it extends circumferentially outward from a position on the radially inner extension of the end of the slot opening 11a. The groove 9a also includes a first groove portion 9a2 (deepest portion) that is formed circumferentially outward from the tapered portion 9a1 (first tapered portion) and the tapered portion 9a3 (second tapered portion). The first groove portion 9a2 is the deepest portion of the groove 9a in the circumferential direction (left-right direction in FIG. 6 ).

[0065] The magnetic wedge 10 has a tapered portion 10b that is inclined toward the anti-gap side from the circumferential center side of the magnetic wedge 10 toward the circumferential outer side (end) thereof.

[0066] 6, in this embodiment, the insertion portion 10a of the magnetic wedge 10 is inserted into the first groove portion 9a2 (deepest portion) located at the outermost side in the circumferential direction of the groove portion 9a, and the stator core 9 and the magnetic wedge 10 are in contact with each other at the first groove portion 9a2 in the circumferential direction of the tapered groove portion 9a. Furthermore, a buffer material 20 is disposed at the position of the tapered portion 9a3 (second tapered portion).

[0067] By configuring this embodiment in this manner, it is possible to obtain the same effects as in embodiment 1, and since the magnetic wedge 10 is in contact with the stator core 9 in the first groove portion 9a2 of the tapered groove portion 9a, the magnetic wedge 10 is fixed and supported not only by the adhesive strength of the varnish 16 but also by metal contact with the stator core 9.

[0068] In the structure of this embodiment, even if an increase in the amount of harmonic magnetic flux causes an increase in heat generation inside the magnetic wedge 10, causing the magnetic wedge 10 to heat up and expand, the thermal expansion of the magnetic wedge 10 can be suppressed by the metal-to-metal contact portion with the stator core 9, eliminating the risk of crushing the varnish 16 in the clearance 15 in the groove 9a. This allows the magnetic wedge 10 to be stably held in the stator core 9, improving the long-term reliability of the rotating electric machine 100. Furthermore, by forming the groove 9a in a tapered shape, the tapered portion 9a3 (second tapered portion) also serves as a positioning guide when inserting the magnetic wedge 10 from the axial direction, improving manufacturability.

[0069] Next, a fifth embodiment will be described with reference to Fig. 7. Fig. 7 is a partially enlarged cross-sectional view of a stator slot 11 according to a fifth embodiment of the present invention. The same components as those in the first to fourth embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0070] In this embodiment, the cross-sectional shape of the magnetic wedge 10 has a protrusion 10 c that protrudes toward the gap 14 side (upper side in FIG. 7 ), and the protrusion 10 c of the magnetic wedge 10 is in contact with the stator core 9 .

[0071] According to this embodiment, the magnetic wedge 10 can be fixed and supported not only at the contact position between the groove 9 a and the magnetic wedge 10 but also at the contact position between the protrusion 10 c of the magnetic wedge and the stator core 9. The gap side of the magnetic wedge 10 (i.e., the protrusion 10 c) is the entrance for magnetic flux from the gap 14, and is the location where the electromagnetic excitation force is strongest due to the large magnetic flux density and time-dependent changes in the magnetic flux. This location receives not only the radial magnetic attraction force toward the gap 14 but also the circumferential electromagnetic excitation force. Therefore, by having the protrusion 10 c of the magnetic wedge contact the stator core 9 as in this embodiment, it is possible to suppress circumferential vibration of the magnetic wedge 10 due to this circumferential electromagnetic excitation force. This increases the holding force of the magnetic wedge 10 and improves the long-term reliability of the rotating electric machine 100.

[0072] Next, a sixth embodiment will be described with reference to Fig. 8. Fig. 8 is a partially enlarged cross-sectional view of a stator slot 11 according to the sixth embodiment of the present invention. The same components as those in the first to fifth embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0073] In this embodiment, a plurality of cushioning materials 20 are stacked in the radial direction. By stacking a plurality of cushioning materials 20, the workability when inserting the magnetic wedge 10 into the groove 9a is improved.

[0074] That is, in the conventional structure, after the stator coil 13 is inserted into the stator slot 11, when the magnetic wedge 10 is inserted from the axial direction, there is a radial pressure from the stator coil 13, and the magnetic wedge 10 is subjected to a static friction force with the groove 9a and the stator coil 13, and a force that exceeds this force is applied in the axial direction by hammering or the like to insert the magnetic wedge 10 into the stator slot 11. However, because the friction coefficients of the surfaces of each component are large, a large force acts on the magnetic wedge 10 when it is inserted, which could lead to damage to the magnetic wedge 10 or destruction of the insulating coating of the stator coil 13.

[0075] In contrast, in the case of the multiple-layered buffer material 20 shown in Figure 8, when the magnetic wedge 10 is inserted from the axial direction, slippage occurs between the multiple layered buffer materials 20, making it easier to insert the stator coil 13 from the axial direction, eliminating the possibility of damage to the magnetic wedge 10 or destruction of the insulating coating of the stator coil 13 during assembly, and improving the long-term reliability of the rotating electric machine 100.

[0076] Next, a seventh embodiment will be described with reference to Fig. 9. Fig. 9 is a partially enlarged cross-sectional view of a stator slot 11 according to a seventh embodiment of the present invention. The same components as those in the first to sixth embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0077] In this embodiment, the cushioning material 20 is folded. That is, the cushioning material 20 is folded at both circumferential ends of the groove portion 9a, and the folded portion 20a of the cushioning material 20 is located on the stator coil 13 side (opposite the gap side). The ends of the folded portion 20a of the cushioning material 20 are arranged to face each other circumferentially inward with a gap 21 between them. The folded cushioning material 20 has spring properties, which makes it easy to ensure the clearance 15 for filling the varnish 16 and facilitates assembly of the rotating electric machine 100.

[0078] The varnish 16 is also absorbed into the gaps between the folded cushioning materials 20, so the clearances 15 are filled with the varnish 16 necessary to adhere the magnetic wedges 10. This allows the magnetic wedges 10 to be fixed and held to the stator 3 by the adhesive force of the varnish 16 filled into the clearances 15 of the grooves 9a.

[0079] Next, an eighth embodiment will be described with reference to Fig. 10. Fig. 10 is a diagram showing a schematic configuration of an electric vehicle according to the eighth embodiment of the present invention.

[0080] In addition to railway vehicles, electric vehicles include electric vehicles that run on a motor powered by battery power, hybrid vehicles that run on dual power from an engine and a motor, plug-in hybrid vehicles that can be charged at home or at a charging station and run on dual power from an engine and a motor, and fuel cell vehicles that generate electricity using hydrogen and oxygen to drive a motor.

[0081] As shown in Figure 10, the electric vehicle 200 is roughly composed of a rotating electric machine 100, a wheel 102a that is rotated and driven by the rotating electric machine 100 via an axle 101a, and a bogie 104a or platform 104b that supports the rotating electric machine 100 via a support member 103a, and the rotating electric machine 100 is one of the rotating electric machines 100 described in Examples 1-7 above.

[0082] That is, the rotating electric machine 100 of the electric vehicle 200 is fixedly supported on a bogie 104a or a platform 104b by a support member 103a, the rotor 2 of the rotating electric machine 100 is directly connected to the axle 101a, and the rotating electric machine 100 is configured to drive the wheel 102a via the axle 101a.

[0083] Generally, a rotating electric machine 100 used in a railway is mounted on a bogie 104a, and is therefore subjected to vibrations caused not only by the rotating electric machine 100 itself but also by external factors, such as vibrations caused by distortions or unevenness of the rails, or vibrations caused by distortions or unevenness of the wheels 102a.

[0084] Furthermore, since the rotating electric machine 100 used in an automobile is mounted on the platform 104b, it is subjected to vibrations caused by the external environment, such as distortions and unevenness of the wheels 102a and the road surface environment.

[0085] For this reason, the rotating electric machine 100 mounted on the electric vehicle 200 is more susceptible to vibration than general rotating electric machines such as industrial motors, and is required to have high resistance to vibration. For this reason, the conventional magnetic wedge holding structure only has sufficient holding force for the magnetic wedge, but has had problems with long-term reliability.

[0086] In contrast to this, in this embodiment, as described above, it is possible to hold the magnetic wedge 10 with long-term reliability, and therefore it is possible to reduce the risk of vibration and cracking of the magnetic wedge 10, so that a highly efficient rotating electric machine 100 can be mounted on the electric vehicle 200, and it is possible to reduce the power consumption of the electric vehicle 200. Furthermore, in this embodiment, it is possible to reduce the power consumption of the electric vehicle 200, and therefore it is possible to reduce CO2 emissions caused by power consumption.

[0087] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0088] REFERENCE SIGNS LIST 1...frame, 2...rotor, 3...stator, 4a, 4b...bearing, 5...shaft, 6...stator teeth, 7...rotor core, 8...end ring, 9...stator core, 9a...groove portion, 9a1...tapered portion (first tapered portion), 9a2...first groove portion (deepest portion), 9a3...tapered portion (second tapered portion), 9a4...second groove portion, 10...magnetic wedge, 10a...insertion portion, 10a1...circumferential end portion, 10b...tapered portion, 10c...convex portion, 11...stator slot, 11a...slot opening, 12...conductor bar, 13...stator coil, 13a...stator coil end, 14...gap, 15...clearance, 16...varnish 18...axial duct, 19...ventilation duct, 20...cushioning material, 20a...folded portion, 21...gap, 100...rotating electric machine, 101a, 101b...axle, 102a, 102b...wheel, 103a, 103b...support member, 104a...bogie, 104b...platform, 200...electric vehicle, C...rotation axis, DR...radial direction, Dθ...circumferential direction, DZ...axial direction

Claims

1. A rotating electric machine comprising a stator and a rotor arranged on the stator via a gap, wherein the stator comprises a stator core having stator slots and a stator coil inserted into the stator core, and wherein a magnetic wedge is provided at the slot opening of the stator slot to hold the stator coil, wherein both ends of the magnetic wedge are inserted into grooves provided in the stator core, the portion of the magnetic wedge inserted into the groove is the insertion portion of the magnetic wedge, the contact position between the groove and the insertion portion of the magnetic wedge is located between the circumferential center of the insertion portion of the magnetic wedge and the circumferential center of the magnetic wedge, and wherein a buffer material wider than the contact position between the groove and the insertion portion of the magnetic wedge is provided between the magnetic wedge and the stator coil.

2. A rotating electric machine according to claim 1, wherein the groove has a tapered portion that is inclined toward the anti-gap side as it moves circumferentially outward from the end position of the slot opening, and the magnetic wedge has a tapered portion that is inclined toward the anti-gap side as it moves from the circumferential center side of the magnetic wedge toward the end side, and when the taper angles of the tapered portion of the groove and the tapered portion of the magnetic wedge are defined as opening angles from the circumferential axis, the taper angle of the groove is less than or equal to the taper angle of the magnetic wedge.

3. A rotating electric machine as claimed in claim 1, wherein the grooves are formed in a stepped pattern with different circumferential widths, and comprise a first groove into which the insertion portion of the magnetic wedge is inserted, and a second groove having a circumferential width narrower than that of the first groove, and wherein the buffer material is disposed in the second groove.

4. A rotating electric machine as described in claim 1, wherein the groove portion comprises a first tapered portion inclined toward the anti-gap side as it moves circumferentially outward from the end position of the slot opening, a second tapered portion inclined toward the gap side as it moves circumferentially outward from a position on the radially inner extension of the end of the slot opening, and a deepest portion formed circumferentially outside the first tapered portion and the second tapered portion, wherein the end of the magnetic wedge is inserted into the deepest portion, and the buffer material is arranged at the position of the second tapered portion.

5. A rotating electric machine according to claim 1, wherein the magnetic wedge has a protrusion that protrudes toward the gap side, and the protrusion is in contact with the stator core.

6. A rotating electric machine according to claim 1, wherein the cushioning material is laminated in a plurality of layers in the radial direction.

7. A rotating electric machine according to claim 6, wherein the cushioning material is folded over.

8. A rotating electric machine according to claim 7, wherein the cushioning material is folded at both circumferential ends, with the folded portions positioned on the opposite side of the gap, and the ends of the folded portions are arranged to face each other circumferentially inward with a gap therebetween.

9. A rotating electric machine according to any one of claims 1 to 8, characterized in that the buffer material is glass fiber paper, glass fiber nonwoven fabric, or polyacetal resin.

10. An electric vehicle comprising a rotating electric machine, wheels that are driven to rotate by the rotating electric machine via axles, and a bogie or platform that supports the rotating electric machine, wherein the rotating electric machine is a rotating electric machine as defined in any one of claims 1 to 8.

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